WorldWideScience

Sample records for benzoapyrene oxidative degradation

  1. [Isolation of highly-effective benzo[a]pyrene degrading strain and its degradation capacity].

    Science.gov (United States)

    Liu, Hai-Bin; Wang, Cui-Ping; Zhang, Zhi-Yuan; Xu, Wei; Hao, Zhi-Neng; Sun, Hong-Wen

    2011-09-01

    One new mycete, which could degrade high concentration (up to 100 mg/L) of benzo[a]pyrene (BaP) in liquid, was isolated from contaminated soil of Beijing Coking Plant by gradually increasing the concentration of BaP in mineral salt medium (MSM) in order to get new microorganism species for remediation of BaP contamination. The strain was identified as Lasiodiplodia theobromae, and its biodegradation ability in liquid was further investigated. The results showed that L. theobromae could utilize BaP as sole carbon and energy sources. The experiment was conducted for 10 days, and the biodegradation rate of BaP was 52.5% +/- 1.5%. Compared to Czapek's mineral medium, MSM was more suitable for L. theobromae, and biodegradation rate was 2.8 percent greater than that by using Czapek's mineral media after 10 days' cultivation. Potato-dextrose nutrient medium could accelrate the biodegradation in early stage, and biodegradation rate of BaP increased by 19.2 percent in the second day. However, the accelration was not significant in the latter period, biodegradation rate was only increased by 5.4 percent after 10 days' cultivation. L. theobromae could tolerate a wide pH range, with the optimum pH of 5. Addition of salicylic and sodium succinate enhanced the biodegradation rates by 6.2 percent and 4.2 percent, respectively, after 10 days' cultivation. Besides BaP, L. theobromae could also degrade high concentration (200 mg/L) of phenanthrene and pyrene, and the biodegradation rates were 70.0% +/- 1.0%, 59.2% +/- 3.2%, and 52.5% +/- 1.5% when they were single substrate and were 21.6% +/- 2.1%, 14.5% +/- 5.5%, and 11.9% +/- 2.2% when they existed in mixture, respectively. The biodegradation rate followed an order of phenanthrene > pyrene > BaP. The co-existence of the three substrates led a reduction in biodegradation. This study provides a new microorganism species for remediation of polycyclic aromatic hydrocarbons (PAHs) contamination in the environment. PMID:22165241

  2. Preliminary evidence of the role of hydrogen peroxide in the degradation of benzo[a]pyrene by a non-white rot fungus Fusarium solani

    Energy Technology Data Exchange (ETDEWEB)

    Veignie, Etienne; Rafin, Catherine; Woisel, Patrice; Cazier, Fabrice

    2004-05-01

    In order to study the enzymatic mechanisms involved in the successive steps of BaP degradation by a Deuteromycete fungus Fusarium solani, we developed an indirect approach by using inhibitors of enzymes. We used either specific inhibitors of peroxidases (i.e. salicylhydroxamic acid) and of cytochrome P-450 (i.e. piperonyl butoxyde) or inhibitors of both enzymes (i.e. potassium cyanide). Surprisingly, no expected decrease of BaP degradation was observed with most inhibitors tested. On the contrary, more BaP was degraded. Only butylated hydroxytoluene, which acts as a free radical scavenger, inhibited BaP degradation. The inhibition of these enzymes, which use H{sub 2}O{sub 2} as a cosubstrat, might have resulted in an increase of hydrogen peroxide availability in the fungal cultures. This enhancement could induce formation of reactive oxygen species (ROS) which might be the agents that initiate benzo[a]pyrene oxidation. This study proposed a hypothetic alternative metabolic pathway involved in PAH metabolism by Fusarium solani. - An alternative metabolic pathway was demonstrated.

  3. Degradation of metabolites of benzo[a]pyrene by coupling Penicillium chrysogenum with KMnO4

    Institute of Scientific and Technical Information of China (English)

    ZANG Shu-yan; LI Pei-jun; YU Xiao-cai; SHI Kun; ZHANG Hui; CHEN Jing

    2007-01-01

    Several main metabolites of benzo[a]pyrene (BaP) formed by Penicillium chrysogenum, Benzo[a]pyrene-l,6-quinone (BP 1,6-quinone), trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP 7,8-diol), 3-hydroxybenzo[a]pyrene (3-OHBP), were identified by high-performance liquid chromatography (HPLC). The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized.The results showed that (1) the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; (2) the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; (3) the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% (w/v), concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.

  4. Alterations of rat liver mitochondrial oxidative phosphorylation and calcium uptake by benzo[a]pyrene

    International Nuclear Information System (INIS)

    We report that oxidative phosphorylation and Ca2+ uptake processes are enhanced in liver mitochondria isolated from benzo[a]pyrene (B[a]P)-treated rats. The carcinogen did not affect either the respiratory control index or the Ca2+ control ratio. B[a]P treatment increased the oxidation rate of several substrates that donate electrons at the level of all three coupling sites, either the ADP- or Ca2+-stimulated rates or those observed after ADP or Ca2+ exhaustion. However, the efficiency of energy coupling was maintained because both ADP/O and Ca2+/site ratios remained unchanged. The electron flow through NADH-oxidase, NADH-duroquinone reductase, NADH-juglone reductase, NADH-cytochrome c reductase, succinate-cytochrome c reductase, and cytochrome c oxidase was enhanced by B[a]P; however, succinate dehydrogenase activity was not affected. All these effects depended on the time post B[a]P administration, with a greater increase close to 48 h after administration of the carcinogen. The contents of cytochromes b, c1, and a + a3 from liver mitochondria, especially those isolated 48 h after B[a]P, were also significantly increased, although cytochrome c levels was just lightly increased 24 h after B[a]P treatment. These results suggest that B[a]P treatment stimulates mitochondrial respiration by increasing the level of several components of the mitochondrial respiratory chain. This may reflect mitochondrial adaptation to the cellular energy requirements of cell division in the neoplastic transformation process

  5. Formaldehyde degradation by catalytic oxidation.

    OpenAIRE

    Shirey, W N; Hall, T. A.; Hanel, E; Sansone, E B

    1981-01-01

    Formaldehyde used for the disinfection of a laminar-flow biological safety cabinet was oxidatively degraded by using a catalyst. This technique reduced the formaldehyde concentration in the cabinet from about 5,000 to about 45 mg/m3 in 8 h. This technique should prove useful in other applications.

  6. Degradation of PAHs in soil by Lasiodiplodia theobromae and enhanced benzo[a]pyrene degradation by the addition of Tween-80.

    Science.gov (United States)

    Wang, Cuiping; Liu, Haibin; Li, Jing; Sun, Hongwen

    2014-09-01

    Benzo[a]pyrene (BaP), a five-ring polycyclic aromatic hydrocarbon (PAH), which has carcinogenic potency, is highly recalcitrant and resistant to microbial degradation. A novel fungus, Lasiodiplodia theobromae (L. theobromae), which can degrade BaP as a sole carbon source in liquid, was isolated in our laboratory. To prompt the further application of L. theobromae in remediation of sites polluted by BaP and other PAHs, the present study was targeted toward the removal of BaP and PAHs from soil by L. theobromae. The degradation of BaP by L. theobromae was studied using a soil spiked with 50 mg/kg BaP. L. theobromae could remove 32.1 % of the BaP after 35 days of cultivation. Phenanthrene (PHE) inhibited BaP degradation as a competitive substrate. The tested surfactants enhanced BaP degradation in soil by different extents, and a removal rate of 92.1 % was achieved at a Tween-80 (TW-80) concentration of 5 g/kg. It was revealed that TW-80 could not only enhance BaP bioavailability by increasing its aqueous solubility and decreasing the size of its colloid particles but also increase enzyme secretion from L. theobromae and the population of L. theobromae. Moreover, ergosterol content together with the biomass C indicated the increase in L. theobromae biomass during the BaP biodegradation process in soils. Finally, a soil from a historically PAH-contaminated field at Beijing Coking Plant in China was tested to assess the feasibility of applying L. theobromae in the remediation of polluted sites. The total removal rate of PAHs by L. theobromae was 53.3 %, which is 13.1 % higher than that by Phanerochaete chrysosporium (P. chrysosporium), an effective PAH degrader. The addition of TW-80 to the field soil further enhanced PAH degradation to 73.2 %. Hence, L. theobromae is a promising novel strain to be implemented in the remediation of soil polluted by PAHs. PMID:24878554

  7. Cellulose degradation by oxidative enzymes

    Directory of Open Access Journals (Sweden)

    Maria Dimarogona

    2012-09-01

    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  8. Advanced Oxidation Degradation of Diclofenac

    International Nuclear Information System (INIS)

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e-aq). The bimolecular reaction rate constants (M-1 s-1) for diclofenac for •OH was (9.29 ± 0.11) x 109, and, for e- aq was (1.53 ± 0.03) x109. Preliminary degradation mechanisms are suggested based on product analysis using 60Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  9. Oxidative degradation of lignin, (2)

    International Nuclear Information System (INIS)

    Specifically 14C-labelled pine kraft lignin was oxidized with hydrogen peroxide and ferrous salts under various conditions. The reaction mixtures were applied to gell filtration on Sephadex G-15. The behavior of the specific carbon atoms in the reaction products was studied from the distribution of the radioactivity relative to that of molecular weight. The gaseous reaction products were separated and identified by gas chromatography, and the radioactivity of these products was measured. The results obtained are summarized as follows: 1. When a small amount of hydrogen peroxide was applied, a part of monomer compounds present in kraft waste liquor was condensed to give dimer and oligomer substances through the intermediate o-quinone. The amount of β- and R-carbon in the polymer fraction of kraft lignin in crased by mild oxidation treatment. 2. When a large amount of hydrogen peroxide was applied, the high molecular fraction of kraft lignin was considerably degraded to low molecular weight products. The ring rupture was remarkably observed. The β-carbon was retained in the high molecular fraction more firmly than other carbons even under severe oxidation conditions. 3. The gaseous reaction products identified were carbon dioxide, methane, acetylene + ethylene, ethane and propene. A large part of methoxyl carbon was converted into carbon dioxide and methane under the conditions described above. (author)

  10. Oxidative degradation of lignin, 1

    International Nuclear Information System (INIS)

    Specifically 14C-labelled pine kraft lignin was oxidized with alkaline hydrogen peroxide under various conditions. The reaction mixture was applied to gell filtration on Sephadex G-15. The behavior of the specific carbon atoms of the degraded lignin was studied from the distribution of radioactivity relative to that of molecular weight. No kraft lignin was decomposed to low molecular weight substances, but polymerized. The amount of alpha -, beta - and gamma -carbons of side chain and ring carbon in the polymer fraction was increased by the oxidation treatment. The amount of these carbon in the polymer fraction increased by increasing the amount of applied hydrogen peroxide. On the other hand, the amount of methoxyl carbon in the polymer fraction increased when a small amount of hydrogen peroxide was applied, and decreased when the amount of hydrogen peroxide was increased. The methoxyl carbon was eliminated to a large extent by treating with alkaline hydrogen peroxide, and a part of it was converted into methane. Ring rupture was not observed under these experimental conditions. (author)

  11. Enhanced oxidation of benzo[a]pyrene by crude enzyme extracts produced during interspecific fungal interaction of Trametes versicolor and Phanerochaete chrysosporium

    Institute of Scientific and Technical Information of China (English)

    Linbo Qian; Baoliang Chen

    2012-01-01

    The effects of interspecific fungal interactions between Trametes versicolor and Phanerochaete chrysosporium on laccase activity and enzymatic oxidation of polycyclic aromatic hydrocarbons (PAHs) were investigated.A deadlock between the two mycelia rather than replacement of one fungus by another was observed on an agar medium.The laccase activity in crude enzyme extracts from interaction zones reached a maximum after a 5-day incubation,which was significantly higher than that from regions of T.versicolor or P.chrysosporium alone.The enhanced induction of laccase activity lasted longer in half nutrition than in normal nutrition.A higher potential to oxidize benzo[a]pyrene by a crude enzyme preparation extracted from the interaction zones was demonstrated.After a 48 hr incubation period,the oxidation of benzo[a]pyrene by crude enzyme extracts from interaction zones reached 26.2%,while only 9.5% of benzo[a]pyrene was oxidized by crude extracts from T.versicolor.The oxidation was promoted by the co-oxidant 2,2'-azinobis-3-ethylbenzthiazoline-6-sulphonate diammonium salt (ABTS).These findings indicate that the application of co-culturing of white-rot fungi in bioremediation is a potential ameliorating technique for the restoration of PAH-contaminated soil.

  12. Modulatory effects of catechin hydrate against genotoxicity, oxidative stress, inflammation and apoptosis induced by benzo(a)pyrene in mice.

    Science.gov (United States)

    Shahid, Ayaz; Ali, Rashid; Ali, Nemat; Hasan, Syed Kazim; Bernwal, Preeti; Afzal, Shekh Mohammad; Vafa, Abul; Sultana, Sarwat

    2016-06-01

    Benzo(a)pyrene [B(a)P], a polycyclic aromatic hydrocarbon (PAH) is a strong mutagen and potent carcinogen. The aim of the present study was to investigate the efficacy of catechin hydrate against B(a)P induced genotoxicity, oxidative stress, inflammation, apoptosis and to explore its underlying molecular mechanisms in the lungs of Swiss albino mice. Administration of B(a)P (125 mg/kg b. wt., p. o.) increased the activities of toxicity markers such as LPO, LDH and B(a)P metabolizing enzymes [NADPH-cytochrome P450 reductase (CYPOR) and microsomal epoxide hydrolase (mEH)] with subsequent decrease in the activities of tissue anti-oxidant armory (SOD, CAT, GPx, GR, GST, QR and GSH). It also caused DNA damage and activation of apoptotic and inflammatory pathway by upregulation of TNF-α, IL-6, NF-kB, COX-2, p53, bax, caspase-3 and down regulating Bcl-2. However, pre-treatment with catechin at a dose of 20 and 40 mg/kg significantly decreased LDH, LPO, B(a)P metabolizing enzymes and increased anti-oxidant armory as well as regulated apoptosis and inflammation in lungs. Histological results also supported the protective effects of catechin. The findings of the present studies suggested that catechin as an effective natural product attenuates B(a)P induced lung toxicity. PMID:27020533

  13. Degradation of 14C labelled Benzo[a]pyrene by a PAH-adapted mixed bacterial culture in the presence of an alkylpolyglycoside-surfactant

    International Nuclear Information System (INIS)

    The biodegradation of the five ring PAH benzo[a]pyrene (BaP) is assumed to be limited by the low water solubility of this compound. A mixed culture of microorganisms - isolated from a PAH-contaminated soil - was able to degrade 14C labelled BaP in mineral medium by co-metabolism with phenanthrene, fluoranthene, anthracene and pyrene as sources of carbon and energy. The mineralisation of these compounds to low levels resulted in an inhibition of the degradation of BaP. After the new addition of the four PAH compounds to the culture medium the mineralisation of BaP started again. A non-ionic surfactant of the alkylpolyglycoside type (Plantacare 2000 UP) increased the concentration of BaP in the culture medium because of solubilization. At high Plantacare concentrations, the degradation of BaP was completely inhibited above the critical micelle concentration (cms). The degradation of the three and four ring PAHs was also inhibited. If the surfactant was metabolised to concentrations below the cmc, an increase of mineralisation of BaP could occur up to 24% in 384 days. (orig.)

  14. Lipid oxidation induced oxidative degradation of cereal beta-glucan.

    Science.gov (United States)

    Wang, Yu-Jie; Mäkelä, Noora; Maina, Ndegwa Henry; Lampi, Anna-Maija; Sontag-Strohm, Tuula

    2016-04-15

    In food systems, lipid oxidation can cause oxidation of other molecules. This research for the first time investigated oxidative degradation of β-glucan induced by lipid oxidation using an oil-in-water emulsion system which simulated a multi-phased aqueous food system containing oil and β-glucan. Lipid oxidation was monitored using peroxide value and hexanal production while β-glucan degradation was evaluated by viscosity and molecular weight measurements. The study showed that while lipid oxidation proceeded, β-glucan degradation occurred. Emulsions containing β-glucan, oil and ferrous ion showed significant viscosity and molecular weight decrease after 1 week of oxidation at room temperature. Elevated temperature (40°C) enhanced the oxidation reactions causing higher viscosity drop. In addition, the presence of β-glucan appeared to retard the hexanal production in lipid oxidation. The study revealed that lipid oxidation may induce the degradation of β-glucan in aqueous food systems where β-glucan and lipids co-exist.

  15. Radiation induced oxidative degradation of polymers

    International Nuclear Information System (INIS)

    The γ-ray induced oxidation of polyethylene and ethylene-propylene copolymer films has been studied to obtain technological information on reducing the period in the radiation resistance testing of polymer materials. The polymers were irradiated under pressurized oxygen atmosphere (0.21 of the order of 10 atm) at high dose rate (0.5 of the order of 1 Mrad/h) in order to accelerate the oxidative degradation. The depth of oxidation region in the film was estimated by the gel fraction measurement. The depth was well agreed with the oxygen penetration region, which was calculated using the observed diffusion coefficient and solubility constant of oxygen in the film and specific rate of the oxygen consumption during irradiation. It was found that the depth of oxidation region was proportional to the square root of [oxygen pressure/ dose rate] and that the testing period could be reduced by higher dose rate irradiation at higher oxygen pressure. (author)

  16. Modeling Degradation in Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Manohar S. Sohal; Anil V. Virkar; Sergey N. Rashkeev; Michael V. Glazoff

    2010-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic no equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential, , within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, no equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  17. ENHANCEMENT OF RESISTANCE TO OXIDATIVE DEGRADATION OF NATURAL RUBBER THROUGH LATEX DEGRADATION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    A fully characterised natural rubber latex was subjected to mechanical degradation by stirring at intervals. The resistance to oxidative degradation of the different samples were studied by measuring the Plasticity retention indices (PRI).The results show that there is an enhancement of the PRI from 57% for the undegraded rubber to 79% for the one-hour degraded sample. Further degradation resulted in decrease of PRI as time of degradation increased. Therefore, the one-hour degraded sample is a special rubber with high oxidation resistance which is of great importance in engineering.

  18. THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

    Institute of Scientific and Technical Information of China (English)

    WEN Zaiqing; HU Xingzhou; SHEN Deyan

    1988-01-01

    The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. Theamorphous region of PP film undergoes degradation prior to the crystalline one.

  19. Neonatal Benzo[a]pyrene Exposure Induces Oxidative Stress and DNA Damage Causing Neurobehavioural Changes during the Early Adolescence Period in Rats.

    Science.gov (United States)

    Patel, Bhupesh; Das, Saroj Kumar; Patri, Manorama

    2016-01-01

    Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) by ingestion of contaminated food and water. Prenatal exposure to benzo[a]pyrene (B[a]P) like PAHs through the placental barrier and neonatal exposure by breast milk and the environment may affect early brain development. In the present study, single intracisternal administration of B[a]P (0.2 and 2.0 µg/kg body weight) to male Wistar rat pups at postnatal day 5 (PND5) was carried out to study its specific effect on neonatal brain development and its consequences at PND30. B[a]P administration showed a significant increase in exploratory and anxiolytic-like behaviour with elevated hippocampal lipid peroxidation and protein oxidation at PND30. Further, DNA damage was estimated in vitro (Neuro2a and C6 cell lines) by the comet assay, and oxidative DNA damage of hippocampal sections was measured in vivo following exposure to B[a]P. DNA strand breaks (single and double) significantly increased due to B[a]P at PND30 in hippocampal neurons and increased the nuclear tail moment in Neuro2a cells. Hippocampal 8-oxo-2'-deoxyguanosine production was significantly elevated showing expression of more TUNEL-positive cells in both doses of B[a]P. Histological studies also revealed a significant reduction in mean area and perimeter of hippocampal neurons in rats treated with B[a]P 2.0 μg/kg, when compared to naïve and control rats. B[a]P significantly increased anxiolytic-like behaviour and oxidative DNA damage in the hippocampus causing apoptosis that may lead to neurodegeneration in adolescence. The findings of the present study address the potential role of B[a]P in inducing oxidative stress-mediated neurodegeneration in the hippocampus through oxidative DNA damage in the early adolescence period of rats. PMID:27271523

  20. Degradation in Solid Oxide Cells During High Temperature Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Manohar Sohal

    2009-05-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells. One goal of that project is to address the technical and degradation issues associated with solid oxide electrolysis cells. This report covers a variety of these degradation issues, which were discussed during a workshop on “Degradation in Solid Oxide Electrolysis Cells and Strategies for its Mitigation,” held in Phoenix, AZ on October 27, 2008. Three major degradation issues related to solid oxide electrolysis cells discussed at the workshop are: • Delamination of O2-electrode and bond layer on steam/O2-electrode side • Contaminants (Ni, Cr, Si, etc.) on reaction sites (triple-phase boundary) • Loss of electrical/ionic conductivity of electrolyte. This list is not all inclusive, but the workshop summary can be useful in providing a direction for future research related to the degradation of solid oxide electrolysis cells.

  1. Evaluation of anti-cancer and anti-oxidative potential of Syzygium Cumini against benzo[a]pyrene (BaP) induced gastric carcinogenesis in mice.

    Science.gov (United States)

    Goyal, P K; Verma, Preeti; Sharma, Priyanka; Parmar, Jyoti; Agarwal, Annapurna

    2010-01-01

    Syzygium cummini extract (SCE) was used in the present study to explore anti-tumor promoting activity in a stomach carcinogenesis model in mice. For this purpose, Swiss albino mice were administered with 1 mg of benzo-a-pyrene (BaP) in 100?l sesame oil by oral gavage twice a week for 4 consecutive weeks. The animals were sacrificed 14 weeks after the last administration of BaP. Oral administration of the extract to pre-treated (i.e. SCE as 25mg/kg b. wt./ day before BaP application for 2 weeks), post-treated (i.e. SCE after BaP application for 8 weeks) and pre-post treated (i.e. SCE for 2 weeks before treatment of BaP followed by the concomitant treatment with SCE and BaP for 4 weeks during and 2 weeks after the last dose of BaP) groups provided a significant reduction in tumor incidence, tumor burden and cumulative number of gastric carcinomas along with a significant elevation of phase II detoxifying enzymes, and inhibition of lipid per oxidation in the stomach. Thus, the present data suggest that the Syzygium cummini extract has anti-tumor and anti-oxidative potential against chemical induced stomach carcinogenesis.

  2. Evaluation of anti-cancer and anti-oxidative potential of Syzygium Cumini against benzo[a]pyrene (BaP) induced gastric carcinogenesis in mice.

    Science.gov (United States)

    Goyal, P K; Verma, Preeti; Sharma, Priyanka; Parmar, Jyoti; Agarwal, Annapurna

    2010-01-01

    Syzygium cummini extract (SCE) was used in the present study to explore anti-tumor promoting activity in a stomach carcinogenesis model in mice. For this purpose, Swiss albino mice were administered with 1 mg of benzo-a-pyrene (BaP) in 100?l sesame oil by oral gavage twice a week for 4 consecutive weeks. The animals were sacrificed 14 weeks after the last administration of BaP. Oral administration of the extract to pre-treated (i.e. SCE as 25mg/kg b. wt./ day before BaP application for 2 weeks), post-treated (i.e. SCE after BaP application for 8 weeks) and pre-post treated (i.e. SCE for 2 weeks before treatment of BaP followed by the concomitant treatment with SCE and BaP for 4 weeks during and 2 weeks after the last dose of BaP) groups provided a significant reduction in tumor incidence, tumor burden and cumulative number of gastric carcinomas along with a significant elevation of phase II detoxifying enzymes, and inhibition of lipid per oxidation in the stomach. Thus, the present data suggest that the Syzygium cummini extract has anti-tumor and anti-oxidative potential against chemical induced stomach carcinogenesis. PMID:21039048

  3. Neonatal exposure to benzo[a]pyrene induces oxidative stress causing altered hippocampal cytomorphometry and behavior during early adolescence period of male Wistar rats.

    Science.gov (United States)

    Patel, Bhupesh; Das, Saroj Kumar; Das, Swagatika; Das, Lipsa; Patri, Manorama

    2016-05-01

    Environmental neurotoxicants like benzo[a]pyrene (B[a]P) have been well documented regarding their potential to induce oxidative stress. However, neonatal exposure to B[a]P and its subsequent effect on anti-oxidant defence system and hippocampal cytomorphometry leading to behavioral changes have not been fully elucidated. We investigated the effect of acute exposure of B[a]P on five days old male Wistar pups administered with single dose of B[a]P (0.2 μg/kg BW) through intracisternal mode. Control group was administered with vehicle i.e., DMSO and a separate group of rats without any treatment was taken as naive group. Behavioral analysis showed anxiolytic-like behavior with significant increase in time spent in open arm in elevated plus maze. Further, significant reduction in fall off time during rotarod test showing B[a]P induced locomotor hyperactivity and impaired motor co-ordination in adolescent rats. B[a]P induced behavioral changes were further associated with altered anti-oxidant defence system involving significant reduction in the total ATPase, Na(+) K(+) ATPase, Mg(2+) ATPase, GR and GPx activity with a significant elevation in the activity of catalase and GST as compared to naive and control groups. Cytomorphometry of hippocampus showed that the number of neurons and glia in B[a]P treated group were significantly reduced as compared to naive and control. Subsequent observation showed that the area and perimeter of hippocampus, hippocampal neurons and neuronal nucleus were significantly reduced in B[a]P treated group as compared to naive and control. The findings of the present study suggest that the alteration in hippocampal cytomorphometry and neuronal population associated with impaired antioxidant signaling and mood in B[a]P treated group could be an outcome of neuromorphological alteration leading to pyknotic cell death or impaired differential migration of neurons during early postnatal brain development. PMID:26946409

  4. Oxidation of PAHs in water solutions by ultraviolet radiation combined with hydrogen peroxide

    OpenAIRE

    Dorota Olejnik; Jacek S. Miller; Stanisław Ledakowicz

    1999-01-01

    The destruction of three polycyclic aromatic hydrocarbons (PAHs): benzo[a]pyrene, chrysene and fluorene in aqueous solution using advanced oxidation process H2O2/UV was investigated. The influence of pH, initial hydrogen peroxide and radical scavenger concentrations on the reaction rate was studied. The oxidation reactions most rapidly run in neutral and acidic solution at optimal hydrogen peroxide concentration (ca. 0.01 M). The degradation of benzo[a]pyrene and chrysene follows radical reac...

  5. Thermal and oxidative degradation of epoxy based layered silicate nanocomposites

    OpenAIRE

    Román Concha, Frida Rosario; Calventus Solé, Yolanda; John M. Hutchinson; Montserrat Ribas, Salvador

    2009-01-01

    The thermal oxidative degradation of several polymer/clay nanocomposites with a range of clay contents has been determined. It is found that the dispersion of the clay in the resin matrix plays a crucial role in the degradation process, and hence emphasises the importance of this aspect of nanocomposite preparation. Peer Reviewed

  6. Cooperative interaction of benzo[a]pyrene and ethanol on plasma membrane remodeling is responsible for enhanced oxidative stress and cell death in primary rat hepatocytes.

    Science.gov (United States)

    Collin, Aurore; Hardonnière, Kevin; Chevanne, Martine; Vuillemin, Julie; Podechard, Normand; Burel, Agnès; Dimanche-Boitrel, Marie-Thérèse; Lagadic-Gossmann, Dominique; Sergent, Odile

    2014-07-01

    Several epidemiologic studies have shown an interactive effect of heavy smoking and heavy alcohol drinking on the development of hepatocellular carcinoma. It has also been recently described that chronic hepatocyte death can trigger excessive compensatory proliferation resulting later in the formation of tumors in mouse liver. As we previously demonstrated that both benzo[a]pyrene (B[a]P), an environmental agent found in cigarette smoke, and ethanol possess similar targets, especially oxidative stress, to trigger death of liver cells, we decided to study here the cellular and molecular mechanisms of the effects of B[a]P/ethanol coexposure on cell death. After an 18-h incubation with 100nM B[a]P, primary rat hepatocytes were supplemented with 50mM ethanol for 5 or 8h. B[a]P/ethanol coexposure led to a greater apoptotic cell death that could be linked to an increase in lipid peroxidation. Plasma membrane remodeling, as depicted by membrane fluidity elevation and physicochemical alterations in lipid rafts, appeared to play a key role, because both toxicants acted with specific complementary effects. Membrane remodeling was shown to induce an accumulation of lysosomes leading to an important increase in low-molecular-weight iron cellular content. Finally, ethanol metabolism, but not that of B[a]P, by providing reactive oxygen species, induced the ultimate toxic process. Indeed, in lysosomes, ethanol promoted the Fenton reaction, lipid peroxidation, and membrane permeabilization, thereby triggering cell death. To conclude, B[a]P exposure, by depleting hepatocyte membrane cholesterol content, would constitute a favorable ground for a later toxic insult such as ethanol intoxication. Membrane stabilization of both plasma membrane and lysosomes might be a potential target for further investigation considering cytoprotective strategies. PMID:24681337

  7. Oxidative Damage to Nucleic Acids and Benzo(apyrene-7,8-diol-9,10-epoxide-DNA Adducts and Chromosomal Aberration in Children with Psoriasis Repeatedly Exposed to Crude Coal Tar Ointment and UV Radiation

    Directory of Open Access Journals (Sweden)

    Lenka Borska

    2014-01-01

    Full Text Available The paper presents a prospective cohort study. Observed group was formed of children with plaque psoriasis (n=19 treated by Goeckerman therapy (GT. The study describes adverse (side effects associated with application of GT (combined exposure of 3% crude coal tar ointment and UV radiation. After GT we found significantly increased markers of oxidative stress (8-hydroxy-2′-deoxyguanosine, 8-hydroxyguanosine, and 8-hydroxyguanine, significantly increased levels of benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE DNA adducts (BPDE-DNA, and significantly increased levels of total number of chromosomal aberrations in peripheral lymphocytes. We found significant relationship between (1 time of UV exposure and total number of aberrated cells and (2 daily topical application of 3% crude coal tar ointment (% of body surface and level of BPDE-DNA adducts. The findings indicated increased hazard of oxidative stress and genotoxic effects related to the treatment. However, it must be noted that the oxidized guanine species and BPDE-DNA adducts also reflect individual variations in metabolic enzyme activity (different extent of bioactivation of benzo[a]pyrene to BPDE and overall efficiency of DNA/RNA repair system. The study confirmed good effectiveness of the GT (significantly decreased PASI score.

  8. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Science.gov (United States)

    Pu, Lumei; Gao, Jinzhang; Hu, Yusen; Liang, Huiguang; Xiao, Wen; Wang, Xingmin

    2008-06-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  9. Oxidation Degradation of Aqueous Carbofuran Induced by Low Temperature Plasma

    Institute of Scientific and Technical Information of China (English)

    PU Lumei; GAO Jinzhang; HU Yusen; LIANG Huiguang; XIAO Wen; WANG Xingmin

    2008-01-01

    The oxidative degradation of aqueous carbofuran, a heavily used toxic carbamate insecticide by low temperature plasma, was investigated. The results show that the treatment efficiency increases with the increase in initial concentration. Raising the treatment temperature and changing the pH value can result in enhanced degradation of carbofuran in solution. The results also show that low temperature plasma treatment can effectively remove chemical oxygen demand (COD) of carbofuran in the solution.

  10. Solid Oxide Electrolysis Cells: Degradation at High Current Densities

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Traulsen, Marie Lund; Hauch, Anne;

    2010-01-01

    The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at 850°C, at current densities of −1.0, −1.5, and −2.0 A/cm2, with a 50:50 (H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode...

  11. Degradation of biomaterials by phagocyte-derived oxidants.

    OpenAIRE

    Sutherland, K; Mahoney, J R; Coury, A J; Eaton, J. W.

    1993-01-01

    Polymers used in implantable devices, although relatively unreactive, may degrade in vivo through unknown mechanisms. For example, polyetherurethane elastomers used as cardiac pacemaker lead insulation have developed surface defects after implantation. This phenomenon, termed "environmental stress cracking," requires intimate contact between polymer and host phagocytic cells, suggesting that phagocyte-generated oxidants might be involved. Indeed, brief exposure of polyetherurethane to activat...

  12. Strength degradation of oxidized graphite support column in VHTR

    International Nuclear Information System (INIS)

    Air-ingress events caused by large pipe breaks are important accidents considered in the design of Very High Temperature Gas-Cooled Reactors (VHTRs). A main safety concern for this type of event is the possibility of core collapse following the failure of the graphite support column, which can be oxidized by ingressed air. In this study, the main target is to predict the strength of the oxidized graphite support column. Through compression tests for fresh and oxidized graphite columns, the compressive strength of IG-110 was obtained. The buckling strength of the IG-110 column is expressed using the following empirical straight-line formula: σcr,buckling=91.34-1.01(L/r). Graphite oxidation in Zone 1 is volume reaction and that in Zone 3 is surface reaction. We notice that the ultimate strength of the graphite column oxidized in Zones 1 and 3 only depends on the slenderness ratio and bulk density. Its strength degradation oxidized in Zone 1 is expressed in the following nondimensional form: σ/σ0=exp(-kd), k=0.114. We found that the strength degradation of a graphite column, oxidized in Zone 3, follows the above buckling empirical formula as the slenderness of the column changes. (author)

  13. Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

    Science.gov (United States)

    Brugmans, M C P; Sӧntjens, S H M; Cox, M A J; Nandakumar, A; Bosman, A W; Mes, T; Janssen, H M; Bouten, C V C; Baaijens, F P T; Driessen-Mol, A

    2015-11-01

    The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications. PMID:26316031

  14. Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

    Science.gov (United States)

    Brugmans, M C P; Sӧntjens, S H M; Cox, M A J; Nandakumar, A; Bosman, A W; Mes, T; Janssen, H M; Bouten, C V C; Baaijens, F P T; Driessen-Mol, A

    2015-11-01

    The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications.

  15. A model for the thermo-oxidative degradation of polyimides

    Science.gov (United States)

    Karra, Satish; Rajagopal, K. R.

    2012-08-01

    Polyimides, due to their superior mechanical behavior at high temperatures, are used in a variety of applications that include aerospace, automobile and electronic packaging industries, as matrices for composites, as adhesives etc. In this paper, we extend our previous model in S. Karra and K. Rajagopal (Mech. Mater. 43(1):54-61, 2011), to include thermo-oxidative degradation of these high temperature polyimides. Appropriate forms for the Helmholtz potential and the rate of dissipation are chosen to describe the degradation. The results for a specific boundary value problem, using our model, compares well with the experimental creep data for PMR-15 resin that is aged in air.

  16. Degradation of 2-hydroxybenzoic acid by advanced oxidation processes

    OpenAIRE

    C. L. P. S. Zanta; Martínez-Huitle, C. A.

    2009-01-01

    In this study, advanced oxidation processes (AOPs) such as the UV/H2O2 and Fenton processes were investigated for the degradation of 2-hydroxybenzoic acid (2-HBA) in lab-scale experiments. Different [H2O2]/[2-HBA] molar ratios and pH values were used in order to establish the most favorable experimental conditions for the Fenton process. For comparison purposes, degradation of 2-HBA was carried out by the UV/H2O2 process under Fenton experimental conditions. The study showed that the Fenton p...

  17. Sulphur mustard degradation on zirconium doped Ti-Fe oxides

    Energy Technology Data Exchange (ETDEWEB)

    Stengl, Vaclav, E-mail: stengl@iic.cas.cz [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i 250 68 Husinec-Rez (Czech Republic); Grygar, Tomas Matys [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR v.v.i 250 68 Husinec-Rez (Czech Republic); Oplustil, Frantisek; Nemec, Tomas [Military Technical Institute of Protection Brno Veslarska 230, 628 00 Brno (Czech Republic)

    2011-09-15

    Highlights: {yields} New stechiometric materials for sulphur mustard degradation. {yields} High degree of degradation, more then 95% h{sup -1}. {yields} One-pot synthesis procedure. - Abstract: Zirconium doped mixed nanodispersive oxides of Ti and Fe were prepared by homogeneous hydrolysis of sulphate salts with urea in aqueous solutions. Synthesized nanodispersive metal oxide hydroxides were characterised as the Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) microanalysis, and acid-base titration. These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (chemical warfare agent HD or bis(2-chloroethyl)sulphide). The presence of Zr{sup 4+} dopant tends to increase both the surface area and the surface hydroxylation of the resulting doped oxides in such a manner that it can contribute to enabling the substrate adsorption at the oxide surface and thus accelerate the rate of degradation of warfare agents. The addition of Zr{sup 4+} to the hydrolysis of ferric sulphate with urea shifts the reaction route and promotes formation of goethite at the expense of ferrihydrite. We discovered that Zr{sup 4+} doped oxo-hydroxides of Ti and Fe exhibit a higher degradation activity towards sulphur mustard than any other yet reported reactive sorbents. The reaction rate constant of the slower parallel reaction of the most efficient reactive sorbents is increased with the increasing amount of surface base sites.

  18. Internal oxidation as a mechanism for steam generator tube degradation

    International Nuclear Information System (INIS)

    Internal oxidation has been proposed as a plausible mechanism for intergranular stress corrosion cracking (IGSCC) of alloy 600 steam generator tubing. This theory can reconcile the main thermodynamic and kinetic characteristics of the observed cracking in hydrogenated primary water. Although secondary side IG attack or IGSCC is commonly attributed to the presence of strong caustic or acidic solutions, more recent evidence suggests that this degradation takes place in a near-neutral environment, possibly dry polluted steam. As a result, internal oxidation is also a feasible mechanism for secondary side degradation. The present paper reviews experimental work carried out in an attempt to determine the validity of this mechanism. The consequences for the expected behaviour of alloys 690 and 800 replacement materials are also described. (author)

  19. Sulphur mustard degradation on zirconium doped Ti-Fe oxides.

    Science.gov (United States)

    Štengla, Václav; Grygar, Tomáš Matys; Opluštil, František; Němec, Tomáš

    2011-09-15

    Zirconium doped mixed nanodispersive oxides of Ti and Fe were prepared by homogeneous hydrolysis of sulphate salts with urea in aqueous solutions. Synthesized nanodispersive metal oxide hydroxides were characterised as the Brunauer-Emmett-Teller (BET) surface area and Barrett-Joiner-Halenda porosity (BJH), X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) microanalysis, and acid-base titration. These oxides were taken for an experimental evaluation of their reactivity with sulphur mustard (chemical warfare agent HD or bis(2-chloroethyl)sulphide). The presence of Zr(4+) dopant tends to increase both the surface area and the surface hydroxylation of the resulting doped oxides in such a manner that it can contribute to enabling the substrate adsorption at the oxide surface and thus accelerate the rate of degradation of warfare agents. The addition of Zr(4+) to the hydrolysis of ferric sulphate with urea shifts the reaction route and promotes formation of goethite at the expense of ferrihydrite. We discovered that Zr(4+) doped oxo-hydroxides of Ti and Fe exhibit a higher degradation activity towards sulphur mustard than any other yet reported reactive sorbents. The reaction rate constant of the slower parallel reaction of the most efficient reactive sorbents is increased with the increasing amount of surface base sites.

  20. A model for the degradation of polyimides due to oxidation

    OpenAIRE

    Karra, Satish; K.R. Rajagopal

    2010-01-01

    Polyimides, due to their superior mechanical behavior at high temperatures, are used in a variety of applications that include aerospace, automobile and electronic packaging industries, as matrices for composites, as adhesives etc. In this paper, we extend our previous model in [S. Karra, K. R. Rajagopal, Modeling the non-linear viscoelastic response of high temperature polyimides, Mechanics of Materials, In press, doi:10.1016/j.mechmat.2010.09.006], to include oxidative degradation of these ...

  1. (-)-Epicatechin Attenuates Degradation of Mouse Oxidative Muscle Following Hindlimb Suspension.

    Science.gov (United States)

    Lee, Icksoo; Hüttemann, Maik; Malek, Moh H

    2016-01-01

    The purpose of this study was to conduct a 14-day hindlimb suspension (HS) with and without (-)-epicatechin supplementation to determine whether (-)-epicatechin treatment can attenuate the loss in muscle degradation, angiogenesis, and mitochondrial signaling in oxidative skeletal muscle. Adult mice were randomized into 3 groups: (a) control (C); (b) HS with vehicle (HS-V); and (c) HS with (-)-epicatechin (HS-(-)-Epi). Animals in the HS-(-)-Epi group received (-)-epicatechin (1.0 mg · kg(-1) of body mass) twice daily through oral gavage. For markers related to muscle degradation, the HS-V group had significantly higher protein expression compared with the control and HS-(-)-Epi groups. Moreover, protein expression for myosin heavy chain type I was significantly reduced by approximately 45% in the HS-V group compared with the control and HS-(-)-Epi groups. In addition, capillarity contact and capillary-to-fiber ratio were significantly higher in the HS-(-)-Epi group compared with the HS-V group. Furthermore, protein expression for thrombospondin-1 was significantly higher in HS-V group compared with the control and HS-(-)-Epi groups. Hindlimb suspension also significantly reduced protein expression for mitochondrial signaling compared with the control and HS-(-)-Epi groups. These findings suggest that (-)-epicatechin supplementation attenuates degradation in oxidative muscles after HS.

  2. Modeling Degradation in Solid Oxide Electrolysis Cells - Volume II

    Energy Technology Data Exchange (ETDEWEB)

    Manohar Motwani

    2011-09-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells (SOECs). To accomplish this, technical and degradation issues associated with the SOECs will need to be addressed. This report covers various approaches being pursued to model degradation issues in SOECs. An electrochemical model for degradation of SOECs is presented. The model is based on concepts in local thermodynamic equilibrium in systems otherwise in global thermodynamic non-equilibrium. It is shown that electronic conduction through the electrolyte, however small, must be taken into account for determining local oxygen chemical potential,, within the electrolyte. The within the electrolyte may lie out of bounds in relation to values at the electrodes in the electrolyzer mode. Under certain conditions, high pressures can develop in the electrolyte just near the oxygen electrode/electrolyte interface, leading to oxygen electrode delamination. These predictions are in accordance with the reported literature on the subject. Development of high pressures may be avoided by introducing some electronic conduction in the electrolyte. By combining equilibrium thermodynamics, non-equilibrium (diffusion) modeling, and first-principles, atomic scale calculations were performed to understand the degradation mechanisms and provide practical recommendations on how to inhibit and/or completely mitigate them.

  3. Degradation of chlorophenol by in-situ electrochemically generated oxidant

    Institute of Scientific and Technical Information of China (English)

    丛燕青; 吴祖成; 叶倩; 谭天恩

    2004-01-01

    A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate ofchlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min-1). Important operating parameters such as current density, sparged oxygen rate were investigated. Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m3/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm2 when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m3/h.

  4. Degradation of chlorophenol by in-situ electrochemically generated oxidant

    Institute of Scientific and Technical Information of China (English)

    丛燕青; 吴祖成; 叶倩; 谭天恩

    2004-01-01

    A novel in-situ electrochemical oxidation method was applied to the degradation of wastewater containing chlorophenol. Under oxygen sparging, the strong oxidant, hydrogen dioxide, could be in-situ generated through the reduction of oxygen on the surface of the cathode. The removal rate ofchlorophenol could be increased 149% when oxygen was induced in the electrochemical cell. The promotion factor was estimated to be about 82.63% according to the pseudo-first-order reaction rate constant (min-1). Important operating parameters such as current density, sparged oxygen rate were investigated.Higher sparged oxygen rate could improve the degradation of chlorophenol. To make full use of oxygen, however, sparged oxygen rate of 0.05 m3/h was adopted in this work. Oxidation-reduction potential could remarkably affect the generation of hydrogen peroxide. It was found that the removal rate of chlorophenol was not in direct proportion to the applied current density. The optimum current density was 3.5 mA/cm2 when initial chlorophenol concentration was 100 mg/L and sparged oxygen rate was 0.05 m3/h.

  5. Benzo(a)pyrene induces oxidative stress, pro-inflammatory cytokines, expression of nuclear factor-kappa B and deregulation of wnt/beta-catenin signaling in colons of BALB/c mice.

    Science.gov (United States)

    Ajayi, Babajide O; Adedara, Isaac A; Farombi, Ebenezer O

    2016-09-01

    The incidence of colonic toxicity has been epidemiologically linked to the consumption of foods contaminated with benzo(a)pyrene (B[a]P). The present study investigated the effects of B[a]P on biomarkers of oxidative stress, inflammation and wnt-signaling in colon of BALB/c mice following exposure to 62.5, 125 and 250 mg/kg of B[a]P for 7 days by oral gavage. Exposure to B[a]P significantly decreased the colonic antioxidant enzymes activities and glutathione level with concomitant significant increase in myeloperoxidase activity, nitric oxide and lipid peroxidation levels. Colon histopathology results showed treatment-related lesions characterized by atrophy, mucosal ulceration and gland erosion in the B[a]P-treated mice. Immunohistochemistry analysis showed that B[a]P treatment increased the protein expression of nuclear factor kappa B, pro-inflammatory cytokines namely tumor necrosis factor alpha and interleukin-1β, as well as cyclooxygenase-2 and inducible nitric oxide synthase in the mice colon. Altered canonical wnt-signaling was confirmed by strong diaminobenzidine staining for p38 mitogen activated protein kinase, β-catenin expression and absence of adenomatous polyposis coli following B[a]P administration. The present data highlight that exposure to B[a]P induces colon injury via induction of oxidative and nitrosative stress, inflammatory biomarkers and dsyregulation wnt/β-catenin signaling, thus confirming the role of B[a]P in the pathogenesis of colonic toxicity. PMID:27338711

  6. Thermal degradation behavior of hypochlorite-oxidized starch nanocrystals under different oxidized levels.

    Science.gov (United States)

    Wei, Benxi; Li, Hongyan; Tian, Yaoqi; Xu, Xueming; Jin, Zhengyu

    2015-06-25

    The thermal degradation behavior of hypochlorite-oxidized starch nanocrystals (OSNCs) was evaluated in this study. Carbonyl and carboxyl groups in OSNCs increased from 0.006 and 0.091mmol/g to 0.033 and 0.129mmol/g, respectively, as the active chlorine concentration increased from 1% to 4% (w/w). Compared with starch nanocrystals (SNCs), the initial degradation temperature of OSNCs with 4% oxidization decreased from 273°C to 253°C. Two degradation processes were detected using differential thermal analysis. The activation energy of the low-temperature process increased with increasing oxidization level because of removal of sulfate esters and reduction of the decomposition products of H2O during oxidation. With increasing temperature, the H2O generating from decarboxylation and decomposition of the carboxyl groups may catalyze SNCs depolymerization, leading to decrease in the activation energy of the high-temperature process. OSNCs (4% oxidized level) can be used in dry process below 253°C to avoid degradation.

  7. Electrochemical degradation of clofibric acid in water by anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sires, Ignasi [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Cabot, Pere Lluis [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Centellas, Francesc [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Garrido, Jose Antonio [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Rodriguez, Rosa Maria [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Arias, Conchita [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: brillas@ub.edu

    2006-10-05

    Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0-12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical ({center_dot}OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl{sub 2}. Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with {center_dot}OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography-mass spectrometry (GC-MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO{sub 2} with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed.

  8. Chromium related degradation of solid oxide fuel cells; Chrom-bezogene Degradation von Festoxid-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, Anita

    2011-05-04

    Solid Oxide Fuel Cells (SOFCs) offer a high potential for application as an auxiliary power unit (APU) for heavy goods vehicles as well as combined heat and power (CHP) systems. SOFCs are especially attractive due to their high efficiencies and the use of different fuel types. However, optimization in terms of long term stability and costs are still necessary. This work characterized the degradation of SOFCs with lanthanum strontium manganite (LSM) cathodes under chromium influence. Galvanostatic cell tests were carried out at 800 C with operation times from 250 - 3000 h and variation of the chromium source and current density. The current densities of j = 0 (A)/(cm{sup 2}), j = 0,3 (A)/(cm{sup 2}) and j = 0,5 (A)/(cm{sup 2}) were applied. The high temperature ferritic alloy Crofer22APU was used as a chromium source. Variation of the chromium source was realized by coating the Crofer22APU insert with the chromium retention layer Mn{sub 3}O{sub 4} and the cathode contact layer LCC10. Cell degradation was analyzed with regard to cell voltage, current density and area specific resistance (ASR). Microstructural alterations of the cathode as well as chromium content and distribution across the cell were investigated after completion of the cell tests. For cells with a chromium source present and operation with a nonzero current density, the course of cell degradation was divided into three phases: a run-in, weak linear degradation and strong linear degradation. A decrease of the chromium release rate by means of different coatings stretched the course of degradation along the timescale. Strong degradation, which is characterized by a significant increase in ASR as well as a decrease of current density at the operating point, was only observed when a chromium source in the setup was comb ined with operation of the cell with a non-zero current density. Operation of the cell with a chromium source but no current density caused a degradation of current density at the

  9. Copper-mediated oxidative degradation of catecholamines and oxidative damage of protein

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, P.R.; Harria, M.I.N.; Felix, J.M.; Hoffmann, M.E. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Biologia

    1997-12-31

    Full text. Degradative oxidation of catecholamines has been a matter of large interest in recent years due to the evidences associating their autoxidation with the etiology of neurotoxic and cardiotoxic processes. In this work we present data on the degradative oxidation of catecholamines of physiological importance: isoproterenol (IP), epinephrine (EP), norepinephrine (NEP), deoxyepinephrine (DEP) and dopamine (DA). The degradative oxidation of the catecholamines was followed by measurement of spectral changes and oxygen consumption by neutral aqueous solutions. The data show that Cu{sup 2+} strongly accelerated the rate of catecholamine oxidation, following the decreasing order; EP>DEP>IP>NEP>DA. The production of superoxide anion radical during catecholamine oxidation was very slow, even in the presence of Cu{sup 2+}. The ability of IP to induce damages on bovine serum albumin (BSA) was determined by measuring the formation of carbonyl-groups in the protein, detected by reduction with tritiated Na BH{sub 4}. The incubation of BSA with IP (50-500{mu}M), in the presence of 100{mu}M Cu{sup 2+} leaded to an increased and dose dependent {sup 3} H-incorporation by the oxidized protein. The production of oxidative damage by IP/Cu{sup 2+} was accompanied by marked BSA fragmentation, detected by SDS-polyacrylamide gel dependent (25-400{mu}M IP) des appearance of the original BSA band and appearance of smaller fragments spread in the gel, when incubation has been done in the presence of 100{mu}M Cu{sup 2+}. These results suggest that copper-catalysed oxidative degradation of proteins induced by catecholamines might be critically involved in the toxic action of these molecules

  10. Degradation of electrochromic film of amorphous tungsten oxide after coloration

    Science.gov (United States)

    Luo, Zhongkuan

    1992-11-01

    The degradation of the electrochromic film of a-WO3 was investigated from the equilibrium state of different driving voltage and the time dependent emf was also obtained in an open or short circuit of zero volts. Based on the mechanism of activation and the principal of chemical reaction kinetics, the correct definition of electrochromic memory was made and a relation of memory was obtained. It was also found that at the initial time of natural bleaching, the change rate of proton concentration in the film was also obtained. According to the mechanism of electrochromic memory, it was indicated that in the open circuit case, the theoretical reaction of the change rate of electric potential was in good agrement with the experimental results, and furthermore, the reaction constant was determined with the experimental data. In the short circuit case, there exist two effects on degradation, the short circuit current caused by the backward emf, and the oxidation of the colored film. The experimental data shows that, in the short circuit case, the degradation strongly depends on the short circuit current and the effect of chemical reaction can be neglected.

  11. Oxidative degradation of organic acids conjugated with sulfite oxidation in flue gas desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.I.

    1986-01-01

    Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (EGD) conditions. The oxidative degradation constant, k/sub 12/, is defined as the ratio of organic acid degradation rate and sulfite oxidation rate after being normalized by the concentrations of organic acid and dissolved S(IV). K/sub 12/, not significantly affected by pH or dissolved oxygen, is around 10/sup -3/ in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Co, Ni, and Fe and is decreased by Mn and halides. Lower dissolved S(IV) magnified these effects. No k/sub 12/ greater than 4 x 10/sup -3/ or smaller than 0.1 x 10/sup -3/ has been observed. A free radical mechanism was proposed to describe the kinetics: (1) sulfate free radical is the major radical responsible to the degradation of organic acid; (2) ferrous generates sulfate radical by reacting with monoxypersulfate to enhance k/sub 12/; (3) manganous consumes sulfate radical to decrease k/sub 12/; (4) dissolved S(IV) competes with ferrous for monoxypersulfate and with manganous for sulfate radical to demonstrate the effects of dissolved S(IV) on k/sub 12/. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product, glutaric semialdehyde - the major retained product with low manganese, glutaric acid and valeric acids - the major retained product with high manganese, lower molecular weight mono- and dicarboxylic acids, other carbonyl compounds, and hydrocarbons.

  12. Exploring methane-oxidizing communities for the co-metabolic degradation of organic micropollutants

    OpenAIRE

    Benner, Jessica; De Smet, Delfien; Ho, Adrian; Kerckhof, Frederiek-Maarten; Vanhaecke, Lynn; Heylen, Kim; Boon, Nico

    2015-01-01

    Methane-oxidizing cultures from five different inocula were enriched to be used for co-metabolic degradation of micropollutants. In a first screening, 18 different compounds were tested for degradation with the cultures as well as with four pure methane-oxidizing bacterial (MOB) strains. The tested compounds included pharmaceuticals, chemical additives, pesticides, and their degradation products. All enriched cultures were successful in the degradation of at least four different pollutants, b...

  13. Different Abilities of Eight Mixed Cultures of Methane-oxidizing Bacteria to Degrade TCE

    DEFF Research Database (Denmark)

    Broholm, Kim; Christensen, Thomas Højlund; Jensen, Bjørn K.

    1993-01-01

    The ability of eight mixed cultures of methane-oxidizing bacteria to degrade trichloroethylene (TCE) was examined in laboratory batch experiments. This is one of the first reported works studying TCE degradation by mixed cultures of methane-oxidizing bacteria at 10°C, a common temperature for soils...... and groundwaters. Only three of the eight mixed cultures were able to degrade TCE, or to degrade TCE fast enough to result in a significant removal of TCE within the experimental time, when the cultures used methane as growth substrate. The same three mixed cultures were able to degrade TCE when they oxidized...... methanol, but only for a limited time period of about 5 days. Several explanations for the discontinued degradation of TCE are given. An experiment carried out to re-activate the methane-oxidizing bacteria after 8 days of growth on methanol by adding methane did not immediately result in degradation...

  14. Methane oxidation and degradation of organic compounds in landfill soil covers

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Kjeldsen, Peter

    2002-01-01

    High rates of methane oxidation and degradation of the lowed halogenated methanes (TCM and DCM) and HCFCs (HCFC-21 and HCFC-22) were found in an investigation of the oxidation of methane and halogenated organic compunds (HOCs) in landfill gas affected soil. The degradation followed zero-order kin......High rates of methane oxidation and degradation of the lowed halogenated methanes (TCM and DCM) and HCFCs (HCFC-21 and HCFC-22) were found in an investigation of the oxidation of methane and halogenated organic compunds (HOCs) in landfill gas affected soil. The degradation followed zero...... in the anaerobic zone in the lower part of soil columns permeated with artificial landfill gas. The lesser-chlorinated compounds were degraded in the upper oxic zone with overlapping gradients of methane and oxygen. Methane oxidation and degradation of HOCs in the top-soils may play a very important role...

  15. Antimutagenic activity of cashew apple (Anacardium occidentale Sapindales, Anacardiaceae fresh juice and processed juice (cajuína against methyl methanesulfonate, 4-nitroquinoline N-oxide and benzo[a]pyrene

    Directory of Open Access Journals (Sweden)

    Ana Amelia Melo-Cavalcante

    2008-01-01

    Full Text Available Cashew apple juice (CAJ, produced from the native Brazilian cashew tree (Anacardium occidentale, and has been reported to have antibacterial, antifungal, antitumor, antioxidant and antimutagenic properties. Both the fresh unprocessed juice and the processed juice (cajuína in Portuguese has been shown to consist of a complex mixture containing high concentrations of anacardic and ascorbic acids plus several carotenoids, phenolic compounds and metals. We assessed both types of juice for their antimutagenic properties against the direct mutagens methyl methanesulfonate (MMS and 4-nitroquinoline-N-oxide (4-NQO and the indirect mutagen benzo[a]pyrene (BaP using pre-treatment, co-treatment and post-treatment assays with Salmonella typhimurium strains TA100, TA102, and TA97a. In pre-treatment experiments with strains TA100 and TA102 the fresh juice showed high antimutagenic activity against MMS but, conversely, co-treatment with both juices enhanced MMS mutagenicity and there was an indication of toxicity in the post-treatment regime. In pre-, co-, and post-treatments with TA97a as test strain, antimutagenic effects were also observed against 4-NQO and BaP. These results suggest that both fresh and processed CAJ can protect the cells against mutagenesis induced by direct and indirect mutagens.

  16. Exploring methane-oxidizing communities for the co-metabolic degradation of organic micropollutants

    NARCIS (Netherlands)

    Benner, Jessica; De Smet, Delfien; Ho, Adrian; Kerckhof, Frederiek-Maarten; Vanhaecke, Lynn; Heylen, Kim; Boon, Nico

    2015-01-01

    Methane-oxidizing cultures from five different inocula were enriched to be used for co-metabolic degradation of micropollutants. In a first screening, 18 different compounds were tested for degradation with the cultures as well as with four pure methane-oxidizing bacterial (MOB) strains. The tested

  17. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Energy Technology Data Exchange (ETDEWEB)

    Henych, Jiří, E-mail: henych@iic.cas.cz [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš [Department of Material Chemistry, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Řež (Czech Republic); Janoš, Pavel; Kuráň, Pavel; Štastný, Martin [Faculty of the Environment, J.E. Purkyně University, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2015-07-30

    Highlights: • Ti–Fe mixed oxides were synthesized via low-temperature one-pot method. • Mixed oxides were used for degradation of parathion methyl. • Pure reference oxide samples showed no degradation ability. • Mixed oxides reached 70% degree of conversion of parathion methyl. - Abstract: Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching <70% was found for the samples with Ti:Fe ratio 0.25:1 and 1:0.25. Contrary, parathion methyl was not degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  18. Thermo-Oxidative Degradation Of SiC/Si3N4 Composites

    Science.gov (United States)

    Baaklini, George Y.; Batt, Ramakrishna T.; Rokhlin, Stanislav I.

    1995-01-01

    Experimental study conducted on thermo-oxidative degradation of composite-material specimens made of silicon carbide fibers in matrices of reaction-bonded silicon nitride. In SiC/Si3N4 composites of study, interphase is 3-micrometers-thick carbon-rich coat on surface of each SiC fiber. Thermo-oxidative degradation of these composites involves diffusion of oxygen through pores of composites to interphases damaged by oxidation. Nondestructive tests reveal critical exposure times.

  19. Comments on "thermal degradation behavior of hypochlorite-oxidized starch nanocrystals under different oxidized levels".

    Science.gov (United States)

    Trache, Djalal

    2016-10-20

    This paper intends to discuss the employment of the Coats-Redfern equation to compute the kinetic parameters of the thermal degradation of hypochlorite-oxidized starch nancrystals by Wei et al. [Carbohydrate Polymers 124 (2015) 124-130]. The original paper has shown some fundamental errors when presenting the Coats-Redfern (CR) integral kinetic model. This CR equation is commonly used to calculate the activation energy of the thermal degradation from a single non isothermal thermogravimetric curve. However, the use of a set of experiments recorded under different heating rates is often required to obtain accurate results, as recommended by the International Confederation for Thermal Analysis and Calorimetry (ICTAC) Kinetics Committee. The present comments are focused on these statements giving some arguments and elucidations concerning the Coats-Redfern equation.

  20. Comments on "thermal degradation behavior of hypochlorite-oxidized starch nanocrystals under different oxidized levels".

    Science.gov (United States)

    Trache, Djalal

    2016-10-20

    This paper intends to discuss the employment of the Coats-Redfern equation to compute the kinetic parameters of the thermal degradation of hypochlorite-oxidized starch nancrystals by Wei et al. [Carbohydrate Polymers 124 (2015) 124-130]. The original paper has shown some fundamental errors when presenting the Coats-Redfern (CR) integral kinetic model. This CR equation is commonly used to calculate the activation energy of the thermal degradation from a single non isothermal thermogravimetric curve. However, the use of a set of experiments recorded under different heating rates is often required to obtain accurate results, as recommended by the International Confederation for Thermal Analysis and Calorimetry (ICTAC) Kinetics Committee. The present comments are focused on these statements giving some arguments and elucidations concerning the Coats-Redfern equation. PMID:27474597

  1. Degradation of organophosphorus pesticide parathion methyl on nanostructured titania-iron mixed oxides

    Science.gov (United States)

    Henych, Jiří; Štengl, Václav; Slušná, Michaela; Matys Grygar, Tomáš; Janoš, Pavel; Kuráň, Pavel; Štastný, Martin

    2015-07-01

    Titania-iron mixed oxides with various Ti:Fe ratio were prepared by homogeneous hydrolysis of aqueous solutions of titanium(IV) oxysulphate and iron(III) sulphate with urea as a precipitating agent. The synthesized samples were characterized by X-ray diffraction, Raman and infrared spectroscopy, scanning and transmission electron microscopy, XRF analysis, specific surface area (BET) and porosity determination (BJH). These oxides were used for degradation of organophosporus pesticide parathion methyl. The highest degradation efficiency approaching degraded on the surfaces of pure oxides. In general, the highest degradation rate exhibited samples consisted of the iron or titanium oxide containing a moderate amount of the admixture. However, distinct correlations between the degradation rate and the sorbent composition were not identified.

  2. Ultrasonic degradation of Rhodamine B in the presence of hydrogen peroxide and some metal oxide.

    Science.gov (United States)

    Mehrdad, Abbas; Hashemzadeh, Robab

    2010-01-01

    In this research, degradation of Rodamine B in the presence of (hydrogen peroxide), (hydrogen peroxide+ultrasound), (hydrogen peroxide+aluminum oxide), (hydrogen peroxide+aluminum oxide+ultrasound with different ultrasound power), (hydrogen peroxide+iron oxide) and (hydrogen peroxide+iron oxide+ultrasound with different ultrasound power) were investigated at 25 degrees C. The apparent rate constants for the examined systems were calculated by pseudo-first-order kinetics. The results indicate that the rate of degradation was accelerated by ultrasound. The rate of degradation was increased by increasing power ultrasound. The efficiency of the (hydrogen peroxide+iron oxide+ultrasound) system for degradation of Rodamine B was higher than the others examined.

  3. Hydrolytic and Oxidative Mechanisms Involved in Cellulose Degradation

    OpenAIRE

    Nutt, Anu

    2006-01-01

    The enzymatic degradation of cellulose is an important process in nature. This thesis has focused on the degradation of cellulose by enzymes from two cellulose-degrading fungi, Hypocrea jecorina and Phanerochaete chrysosporium, including both the action of the individual enzymes and their synergistic interplay. The end-preference of cellobiohydrolases on crystalline cellulose was studied. Cellobiohydrolases belonging to glycosyl hydrolase (GH) family 7 were found to hydrolyse cellulose proce...

  4. Degradation of triketone herbicides, mesotrione and sulcotrione, using advanced oxidation processes

    International Nuclear Information System (INIS)

    Highlights: • Thirteen products are identified during all degradations for both pesticides. • In all degradations same products and mechanism was observed for both pesticides. • Dominant mechanism for all degradations starts with attack on the carbonyl group. • Only in ozone and DBD degradation one product is formed in radical reaction. • Only in Fenton degradation opening of benzene ring occurs. -- Abstract: Degradation of two triketone herbicides, mesotrione and sulcotrione, was studied using four different advanced oxidation processes (AOPs): ozonization, dielectric barrier discharge (DBD reactor), photocatalysis and Fenton reagent, in order to find differences in mechanism of degradation. Degradation products were identified by high performance liquid chromatography (HPLC–DAD) and UHPLC–Orbitrap–MS analyses. A simple mechanism of degradation for different AOP was proposed. Thirteen products were identified during all degradations for both pesticides. It was assumed that the oxidation mechanisms in the all four technologies were not based only on the production and use of the hydroxyl radical, but they also included other kinds of oxidation mechanisms specific for each technology. Similarity was observed between degradation mechanism of ozonation and DBD. The greatest difference in the products was found in Fenton degradation which included the opening of benzene ring. When degraded with same AOP pesticides gave at the end of treatment the same products. Global toxicity and COD value of samples was determined after all degradations. Real water sample was used to study influence of organic matter on pesticide degradation. These results could lead to accurate estimates of the overall effects of triketone herbicides on environmental ecosystems and also contributed to the development of improved removal processes

  5. {sup 17}O NMR investigation of oxidative degradation in polymers under gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    ALAM,TODD M.; CELINA,MATHIAS C.; ASSINK,ROGER A.; CLOUGH,ROGER LEE; GILLEN,KENNETH T.

    2000-03-08

    The {gamma}-irradiated-oxidation of pentacontane (C{sub 50}H{sub 102}) and the polymer polyisoprene was investigated as a function of oxidation level using {sup 17}O nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that by using {sup 17}O labeled O{sub 2} gas during the {gamma}-irradiation process, details about the oxidative degradation mechanisms can be directly obtained from the analysis of the {sup 17}O NMR spectra. Production of carboxylic acids is the primary oxygen-containing functionality during the oxidation of pentacontane, while ethers and alcohols are the dominant oxidation product observed for polyisoprene. The formation of ester species during the oxidation process is very minor for both materials, with water also being produced in significant amounts during the radiolytic oxidation of polyisoprene. The ability to focus on the oxidative component of the degradation process using {sup 17}O NMR spectroscopy demonstrates the selectivity of this technique over more conventional approaches.

  6. Hydrolytic Degradation of Poly (ethylene oxide)-block-Polycaprolactone Worm Micelles

    OpenAIRE

    Geng, Yan; Discher, Dennis E.

    2005-01-01

    Spherical micelles and nanoparticles made with degradable polymers have been of great interest for therapeutic application, but degradation induced changes in a spherical morphology can be subtle and mechanism/kinetics appears poorly understood. Here, we report the first preparation of giant and flexible worm micelles self-assembled from degradable copolymer poly (ethylene oxide)-block-polycaprolactone. Such worm micelles spontaneously shorten to generate spherical micelles, triggered by poly...

  7. Oxidative degradation of polylactide (PLA) and its effects on physical and mechanical properties

    OpenAIRE

    RASSELET, Damien; Ruellan, Alexandre; GUINAULT, Alain; MIQUELARD-GARNIER, Guillaume; Sollogoub, Cyrille; Fayolle, Bruno

    2014-01-01

    International audience The thermo-oxidative degradation of polylactide (PLA) films was studied between 70 and 150 C. It was shown that the oxidative degradation of PLA leads to a random chain cission responsible for a reduction of the molar mass. These molar mass changes affect Tg and the degree of crystallinity, and it was found that Tg decreases according to the Fox-Flory theory whereas the degree of crystallinity increases due to a chemicrystallization process. A correlation between mol...

  8. Degradation of polyethylene induced by plasma in oxidizing atmospheres

    International Nuclear Information System (INIS)

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  9. Efficient oxidative degradation of 2-chlorophenol and 4-chlorophenol over supported CuO-based catalysts

    Institute of Scientific and Technical Information of China (English)

    Jingjing Li; Yang Hu; Wenhui Lü; Lei Shi; Qi Sun; Yonggang Zhou; Jianfeng Xu; Jian Wang; Bizhong Shen

    2011-01-01

    A series of metal oxide catalysts for catalytic oxidative degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) were prepared,and the supported CuO catalysts were studied particularly.The supported CuO catalysts were characterized by XRD and NH3-TPD techniques,in which CuO/γ-Al2O3 exhibited high degradation activity.The addition of Na2O or K2O into CuO/γ-Al2O3 improved the oxidative degradation of CPs remarkably,in which Na2O was more efficient than K2O.Over CuO/γ-Al2O3-Na2O,CPs were completely converted and the liberation of the inorganic chloride from 2-CP or 4-CP reached 97% or 100% respectively at 30 ℃ for 2 h.The supported CuO catalysts with good dispersion of CuO particles and less acid sites were favorable for the efficient oxidative degradation of CPs.In addition,the initial pH of the reaction solution was found to be an important factor which influenced the catalytic oxidative degradation of CPs and the initial pH of 11.2 and 9.8 was preferred for the oxidative degradation of 2-CP and 4-CP respectively over CuO/γ-Al2O3 catalyst.

  10. Roles of manganese oxides in degradation of phenol under UV-Vis irradiation: Adsorption, oxidation, and photocatalysis

    Institute of Scientific and Technical Information of China (English)

    Qin Zhang; Xiaodi Cheng; Chen Zheng; Xionghan Feng; Guohong Qiu; Wenfeng Tan; Fan Liu

    2011-01-01

    Manganese oxides are known as one type of semiconductors,but their photocatalysis characteristics have not teen deeply explored.In this study,photocatalytic degradation of phenol using several synthesized manganese oxides,i.e,acidic birnessite (BIR-H),alkaline birnessite (BIR-OH),cryptomelane (CRY) and todorokite (TOD),were comparatively investigated.To elucidate phenol degradation mechanisms,X-ray diffraction (XRD),ICP-AES (inductively coupled plasma-atomic emission spectroscopy),TEM (transmission electronic microscope),N2 physisorption at 77 K and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to characterize the structural,compositional,morphological,specific surface area and optical absorption properties of the manganese oxides.After 12 hr of UV-Vis irradiation,the total organic carbon (TOC) removal rate reached 62.1%,43.1%,25.4%,and 22.5% for cryptomelane,acidic birnessite,todorokite and alkaline birnessite,respectively.Compared to the reactions in the dark condition,UVVis exposure improved the TOC removal rates by 55.8%,31.9%,23.4% and 17.9%.This suggests a weak ability of manganese oxides to degrade phenol in the dark condition,while UV-Vis light irradiation could significantly enhance phenol degradation.The manganese minerals exhibited photocatalytic activities in the order of:CRY > BIR-H > TOD > BIR-OH.There may be three possible mechanisms for photochemical degradation:(1) direct photolysis of phenol; (2) direct oxidation of phenol by manganese oxides; (3) photocatalytic oxidation of phenol by manganese oxides.Photocatalytic oxidation of phenol appeared to be the dominant mechanism.

  11. Roles of manganese oxides in degradation of phenol under UV-Vis irradiation: adsorption, oxidation, and photocatalysis.

    Science.gov (United States)

    Zhang, Qin; Cheng, Xiaodi; Zheng, Chen; Feng, Xionghan; Qiu, Guohong; Tan, Wenfeng; Liu, Fan

    2011-01-01

    Manganese oxides are known as one type of semiconductors, but their photocatalysis characteristics have not been deeply explored. In this study, photocatalytic degradation of phenol using several synthesized manganese oxides, i.e, acidic birnessite (BIR-H), alkaline birnessite (BIR-OH), cryptomelane (CRY) and todorokite (TOD), were comparatively investigated. To elucidate phenol degradation mechanisms, X-ray diffraction (XRD), ICP-AES (inductively coupled plasma-atomic emission spectroscopy), TEM (transmission electronic microscope), N2 physisorption at 77 K and UV-visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to characterize the structural, compositional, morphological, specific surface area and optical absorption properties of the manganese oxides. After 12 hr of UV-Vis irradiation, the total organic carbon (TOC) removal rate reached 62.1%, 43.1%, 25.4%, and 22.5% for cryptomelane, acidic birnessite, todorokite and alkaline birnessite, respectively. Compared to the reactions in the dark condition, UV-Vis exposure improved the TOC removal rates by 55.8%, 31.9%, 23.4% and 17.9%. This suggests a weak ability of manganese oxides to degrade phenol in the dark condition, while UV-Vis light irradiation could significantly enhance phenol degradation. The manganese minerals exhibited photocatalytic activities in the order of: CRY > BIR-H > TOD > BIR-OH. There may be three possible mechanisms for photochemical degradation: (1) direct photolysis of phenol; (2) direct oxidation of phenol by manganese oxides; (3) photocatalytic oxidation of phenol by manganese oxides. Photocatalytic oxidation of phenol appeared to be the dominant mechanism.

  12. COMPARISON OF DIFFERENT ADVANCED OXIDATION PROCESSES DEGRADING P-CHLOROPHENOL IN AQUEOUS SOLUTION

    OpenAIRE

    H. Movahedyan ، A. M. Seid Mohammadi ، A. Assadi

    2009-01-01

    In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H2O2, microwave/H2O2 and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation...

  13. Diclofenac and 2‐anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver

    OpenAIRE

    Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

    2012-01-01

    Summary The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio‐MnOx), biogenic silver nanoparticles (Bio‐Ag0) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2‐anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by...

  14. Oxidative degradation of organic acids conjugated with sulfite oxidation in flue-gas desulfurization. Final report, June 1984-June 1986

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.J.; Rochelle, G.T.

    1988-02-01

    This report gives results of a study of organic acid-degradation conjugated with sulfite oxidation under flue-gas desulfurization (FGD) conditions. The oxidative degradation constant, k12, is defined as the ratio of organic-acid degradation rate and sulfite oxidation-rate times the ratio of the concentrations of dissolved S(IV) and organic acid. It is not significantly affected by pH or dissolved oxygen in the absence of Mn or Fe. However, k12 is increased by certain transition metals such as Fe, Co, and Ni and is decreased by Mn and halides. Lower dissolved S(IV) magnifies these effects. A free-radical mechanism was proposed to describe the kinetics. Hydroxy and sulfonated carboxylic acids degrade approximately three times slower than saturated dicarboxylic acids; while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude faster. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide (the major product), smaller dicarboxylic acids, monocarboxylic acids, other carbonyl compounds, and hydrocarbons.

  15. Oxidative degradation of organic acid conjugated with sulfite oxidation in flue gas desulfurization: products, kinetics and mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.J.; Rochelle, G.T.

    1987-03-01

    Organic acid degradation conjugated with sulfite oxidation has been studied under flue gas desulfurization (FGD) conditions. The oxidative degradation constant k/sub 12/ is defined as the ratio of organic acid degradation rate and sulfite oxidation rate times the ratio of the concentration of dissolved S(IV) and organic acid. It is not significantly affected by pH or dissolved oxygen in the absence of manganese or iron. However, k/sub 12/ is increased by certain transition metals such as Fe, Co, and Ni and is decreased by Mn and halides. Lower dissolved S(IV) magnifies these effects. A free radical mechanism was proposed to describe the kinetics. Hydroxy and sulfonated carboxylic acids degrade approximately 3 times slower than saturated dicarboxylic acids, while maleic acid, an unsaturated dicarboxylic acid, degraded an order of magnitude factor. A wide spectrum of degradation products of adipic acid were found, including carbon dioxide - the major product - smaller dicarboxylic acids, monocarboxylic acids, other carbonyl compounds, and hydrocarbons. 30 references, 7 figures, 7 tables.

  16. Thermal characterization and detailed kinetic analysis of Cassava starch thermo-oxidative degradation.

    Science.gov (United States)

    Janković, Bojan

    2013-06-20

    Detailed kinetic analysis of Cassava starch thermo-oxidative degradation was performed, using thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) at four different heating rates. It was found that degradation process is very complex, as identified through continuous change of apparent activation energy with degree of degradation. It was established that process proceeds through three main degradation stages with one additional sub-stage attached to the second degradation stage, which was detected by appearance of "shoulder" on DTG curves. It was found that most important degradation stage can be described by "lumped" model, which implies that free radicals simultaneously attack both linear and branched molecular forms of the starch. This is characterized by an unusually high value of obtained reaction order (n=3.49). Application of nonlinear least squares method was confirmed the reliability of evaluated kinetic parameters and function of reaction mechanism, which were derived on the basis of other kinetic methods.

  17. Degradable polyethylene nanocomposites with silica, silicate and thermally reduced graphene using oxo-degradable pro-oxidant.

    Science.gov (United States)

    Patwary, Fakhruddin; Mittal, Vikas

    2015-12-01

    Polyethylene nanocomposites with silica, alumino-silicate and thermally reduced graphene were generated by adding pro-oxidant additive. Additive resulted in early degradation of pure polymer, however, the degradation was delayed in the presence of fillers. Graphene resulted in maximum extent of enhancement of peak degradation temperature (13-14 °C depending on the additive content) followed by silicate and silica. Additive also resulted in enhancement of polymer crystallinity, which was further aided by the filler, though no change in peak melting and crystallization temperatures was observed. The graphene and silicate particles were also observed to be uniformly dispersed in polymer matrix, whereas some aggregates were present in silica based composites. In graphene composite with 2.5 wt% additive content, the tensile modulus was increased by 1.95 times that of pure polymer. Increasing the additive content was also observed to enhance the mechanical performance. For instance, graphene nanocomposite with 1 % additive content had 40 % and 33 % increment in storage modulus at 50 °C and 70 °C respectively as compared to pure PE. The thick plaques of composites exhibited oxo-degradation in the presence of pro-oxidant with silica and silicate composites with 2.5 wt% additive having 100 % degree of embrittlement in 15-16 months at 30 °C. Graphene composites also exhibited ∼50 % embrittlement for the same conditions. The filler particles were observed to delay the time needed to attain embrittlement due to reduction in oxygen permeation in the matrix as well as UV absorption, however, these materials confirmed that degradation of the materials could be successfully tuned without sacrificing the mechanical, thermal and rheological properties of the nanocomposites. PMID:27441233

  18. Oxidative Degradation of Aminosilica Adsorbents Relevant to Postcombustion CO 2 Capture

    KAUST Repository

    Bollini, Praveen

    2011-05-19

    Coal-fired power plant flue gas exhaust typically contains 3-10% oxygen. While it is known that the monoethanolamine (MEA) oxidative degradation rate is a critical parameter affecting liquid amine absorption processes, the effect of oxygen on the stability of solid amine adsorbents remains unexplored. Here, oxidative degradation of aminosilica materials is studied under accelerated oxidizing conditions to assess the stability of different supported amine structures to oxidizing conditions. Adsorbents constructed using four different silane coupling agents are evaluated, three with a single primary, secondary, or tertiary amine at the end of a propyl surface linker, with the fourth having one secondary propylamine separated from a primary amine by an ethyl linker. Under the experimental conditions used in this study, it was found that both amine type and proximity had a significant effect on oxidative degradation rates. In particular, the supported primary and tertiary amines proved to be stable to the oxidizing conditions used, whereas the secondary amines degraded at elevated treatment temperatures. Because secondary amines are important components of many supported amine adsorbents, it is suggested that the oxidative stability of such species needs to be carefully considered in assessments of postcombustion CO2 capture processes based on supported amines. © 2011 American Chemical Society.

  19. Structural basis for cellobiose dehydrogenase action during oxidative cellulose degradation

    OpenAIRE

    Tan, Tien-Chye; Kracher, Daniel; Gandini, Rosaria; Sygmund, Christoph; Kittl, Roman; Haltrich, Dietmar; Hallberg, B Martin; Ludwig, Roland; Divne, Christina

    2015-01-01

    A new paradigm for cellulose depolymerization by fungi focuses on an oxidative mechanism involving cellobiose dehydrogenases (CDH) and copper-dependent lytic polysaccharide monooxygenases (LPMO); however, mechanistic studies have been hampered by the lack of structural information regarding CDH. CDH contains a haem-binding cytochrome (CYT) connected via a flexible linker to a flavin-dependent dehydrogenase (DH). Electrons are generated from cellobiose oxidation catalysed by DH and shuttled vi...

  20. Ammonium-oxidizing bacteria facilitate aerobic degradation of sulfanilic acid in activated sludge.

    Science.gov (United States)

    Chen, Gang; Ginige, Maneesha P; Kaksonen, Anna H; Cheng, Ka Yu

    2014-01-01

    Sulfanilic acid (SA) is a toxic sulfonated aromatic amine commonly found in anaerobically treated azo dye contaminated effluents. Aerobic acclimatization of SA-degrading mixed microbial culture could lead to co-enrichment of ammonium-oxidizing bacteria (AOB) because of the concomitant release of ammonium from SA oxidation. To what extent the co-enriched AOB would affect SA oxidation at various ammonium concentrations was unclear. Here, a series of batch kinetic experiments were conducted to evaluate the effect of AOB on aerobic SA degradation in an acclimatized activated sludge culture capable of oxidizing SA and ammonium simultaneously. To account for the effect of AOB on SA degradation, allylthiourea was used to inhibit AOB activity in the culture. The results indicated that specific SA degradation rate of the mixed culture was negatively correlated with the initial ammonium concentration (0-93 mM, R²= 0.99). The presence of AOB accelerated SA degradation by reducing the inhibitory effect of ammonium (≥ 10 mM). The Haldane substrate inhibition model was used to correlate substrate concentration (SA and ammonium) and oxygen uptake rate. This study revealed, for the first time, that AOB could facilitate SA degradation at high concentration of ammonium (≥ 10 mM) in an enriched activated sludge culture.

  1. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes

    International Nuclear Information System (INIS)

    Highlights: • NP4EO in industrial effluents can be treated before reaching water reservoirs. • Advanced oxidation processes are proposed for the degradation of NP4EO. • The degradation rate depends mainly on the light intensity. • The mineralization rate depends mainly on the current density. • Photo-assisted electrochemical oxidation showed the best degradation results. - Abstract: Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis – HP, eletrochemical oxidation – EO and photo-assisted electrochemical oxidation – PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250 W lamp and a current density of 10 mA/cm2 showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources

  2. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Wohlmuth da Silva, Salatiel, E-mail: salatielws@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS) – Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGEM), Av. Bento Gonçalves, 9500, Porto Alegre, RS (Brazil); Klauck, Cláudia Regina, E-mail: claudiark@feevale.br [Universidade Feevale, Campus II ERS-239, 2755, Novo Hamburgo, RS (Brazil); Siqueira, Marco Antônio, E-mail: marcor@feevale.br [Universidade Feevale, Campus II ERS-239, 2755, Novo Hamburgo, RS (Brazil); Bernardes, Andréa Moura, E-mail: amb@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS) – Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGEM), Av. Bento Gonçalves, 9500, Porto Alegre, RS (Brazil)

    2015-01-23

    Highlights: • NP{sub 4}EO in industrial effluents can be treated before reaching water reservoirs. • Advanced oxidation processes are proposed for the degradation of NP{sub 4}EO. • The degradation rate depends mainly on the light intensity. • The mineralization rate depends mainly on the current density. • Photo-assisted electrochemical oxidation showed the best degradation results. - Abstract: Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis – HP, eletrochemical oxidation – EO and photo-assisted electrochemical oxidation – PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NP{sub n}EO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NP{sub n}EO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NP{sub n}EO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250 W lamp and a current density of 10 mA/cm{sup 2} showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NP{sub n}EO, avoiding the contamination of water resources.

  3. Investigation of Oxidative Degradation in Polymers Using (17)O NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Todd M.; Celina, Mathew; Assink, Roger A.; Clough, Roger L.; Gillen, Kenneth T.; Wheeler David R.

    1999-07-20

    The thermal oxidation of pentacontane (C{sub 50}H{sub 102}), and of the homopolymer polyisoprene, has been investigated using {sup 17}O NMR spectroscopy. By performing the oxidation using {sup 17}O labeled O{sub 2} gas, it is possible to easily identify degradation products, even at relatively low concentrations. It is demonstrated that details of the degradation mechanism can be obtained from analysis of the {sup 17}O NMR spectra as a function of total oxidation. Pentacontane reveals the widest variety of reaction products, and exhibits changes in the relative product distributions with increasing O{sub 2} consumption. At low levels of oxygen incorporation, peroxides are the major oxidation product, while at later stages of degradation these species are replaced by increasing concentrations of ketones, alcohols, carboxylic acids and esters. Analyzing the product distribution can help in identification of the different free-radical decomposition pathways of hydroperoxides, including recombination, proton abstraction and chain scission, as well as secondary reactions. The {sup 17}O NMR spectra of thermally oxidized polyisoprene reveal fewer degradation functionalities, but exhibit an increased complexity in the type of observed degradation species due to structural features such as unsaturation and methyl branching. Alcohols and ethers formed from hydrogen abstraction and free radical termination.

  4. INFLUENCE OF ETHYLENE-OXIDE GAS TREATMENT ON THE IN-VITRO DEGRADATION BEHAVIOR OF DERMAL SHEEP COLLAGEN

    NARCIS (Netherlands)

    DAMINK, LHHO; DIJKSTRA, PJ; VANLUYN, MJA; VANWACHEM, PB; NIEUWENHUIS, P; FEIJEN, J

    1995-01-01

    The influence of ethylene oxide gas treatment on the in vitro degradation behavior of noncrosslinked, glutaraldehyde crosslinked or hexamethylene diisocyanate crosslinked dermal sheep collagen (DSC) using bacterial collagenase is described. The results obtained were compared with the degradation beh

  5. Oxidative degradation of salicylic acid by sprayed WO3 photocatalyst

    International Nuclear Information System (INIS)

    Highlights: • The photoactivity of sprayed WO3 thin film. • Photoelectrocatalytic degradation of salicylic acid. • Reaction kinetics and mineralization of pollutants by COD. - Abstract: The WO3 thin films were deposited using spray pyrolysis technique. The prepared WO3 thin films were characterized using photoelectrochemical (PEC), X-ray diffraction, atomic force microscopy (AFM), and UV–vis absorbance spectroscopy techniques. PEC measurements of WO3 films deposited at different deposition temperatures were carried out to study photoresponse. The maximum photocurrent (Iph = 261 μA/cm2) was observed for the film deposited at the 225 °C. The monoclinic crystal structure of WO3 has been confirmed from X-ray diffraction studies. AFM studies were used to calculate particle size and average roughness of the films. Optical absorbance was studied to estimate the bandgap energy of WO3 thin film which was about 2.65 eV. The photoelectrocatalytic activity of WO3 film was studied by degradation of salicylic acid with reducing concentrations as function of reaction time. The WO3 photocatalyst degraded salicylic acid to about 67.14% with significant reduction in chemical oxygen demand (COD) value

  6. Degradation of Ultra-Thin Gate Oxide NMOSFETs under CVDT and SHE Stresses

    Institute of Scientific and Technical Information of China (English)

    HU Shi-Gang; CAO Yan-Rong; HAO Yue; MA Xiao-Hua; CHEN Chi; WU Xiao-Feng; ZHOU Qing-Jun

    2008-01-01

    Degradation of device under substrate hot-electron (SHE) and constant voltage direct-tunnelling (CVDT) stresses are studied using NMOSFET with 1.4-nm gate oxides. The degradation of device parameters and the degradation of the stress induced leakage current (SILC) under these two stresses are reported. The emphasis of this paper is on SILC and breakdown of ultra-thin-gate-oxide under these two stresses. SILC increases with stress time and several soft breakdown events occur during direct-tunnelling (DT) stress. During SHE stress, SILC firstly decreases with stress time and suddenly jumps to a high level, and no soft breakdown event is observed. For DT injection, the positive hole trapped in the oxide and hole direct-tunnelling play important roles in the breakdown.For SHE injection, it is because injected hot electrons accelerate the formation of defects and these defects formed by hot electrons induce breakdown.

  7. Comparison of factors influencing trichloroethylene degradation by toluene-oxidizing bacteria.

    OpenAIRE

    Leahy, J G; Byrne, A M; Olsen, R H

    1996-01-01

    The degradation of trichloroethylene (TCE) by toluene-oxidizing bacteria has been extensively studied, and yet the influence of environmental conditions and physiological characteristics of individual strains has received little attention. To consider these effects, the levels of TCE degradation by strains distinguishable on the basis of toluene and nitrate metabolism were compared under aerobic or hypoxic conditions in the presence and absence of nitrate and an exogenous electron donor, lact...

  8. Photocatalytic efficiency of iron oxides: Degradation of 4-chlorophenol

    Science.gov (United States)

    Bakardjieva, Snejana; Stengl, Vaclav; Subrt, Jan; Houskova, Vendula; Kalenda, Petr

    2007-05-01

    The photocatalytic activity of ferrihydrite Fe5O7(OH)×4H2O synthesized by homogeneous precipitation with urea and products obtained by calcinations of as-precipitated ferrihydrite at different temperatures (200 1000 °C) was studied. The microstructure and surface properties of raw precipitate and all heated samples were characterized by means of HRTEM, SEM, BET/BJH and RTG analyses. Kinetics of disappearance of 4-chlorophenol (4-CP) in aqueous solution was used as a test reaction. We have found that hematite Fe2O3 obtained at 1000 °C exhibited satisfied photocatalytic efficiency on the degradation of 4-CP.

  9. Degradation kinetics of chlorinated aliphatic hydrocarbons by methane oxidizers naturally-associated with wetland plant roots.

    Science.gov (United States)

    Powell, C L; Goltz, M N; Agrawal, A

    2014-12-01

    Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants that can be removed from the environment by natural attenuation processes. CAH biodegradation can occur in wetland environments by reductive dechlorination as well as oxidation pathways. In particular, CAH oxidation may occur in vegetated wetlands, by microorganisms that are naturally associated with the roots of wetland plants. The main objective of this study was to evaluate the cometabolic degradation kinetics of the CAHs, cis-1,2-dichloroethene (cisDCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1TCA), by methane-oxidizing bacteria associated with the roots of a typical wetland plant in soil-free system. Laboratory microcosms with washed live roots investigated aerobic, cometabolic degradation of CAHs by the root-associated methane-oxidizing bacteria at initial aqueous [CH4] ~1.9mgL(-1), and initial aqueous [CAH] ~150μgL(-1); cisDCE and TCE (in the presence of 1,1,1TCA) degraded significantly, with a removal efficiency of approximately 90% and 46%, respectively. 1,1,1TCA degradation was not observed in the presence of active methane oxidizers. The pseudo first-order degradation rate-constants of TCE and cisDCE were 0.12±0.01 and 0.59±0.07d(-1), respectively, which are comparable to published values. However, their biomass-normalized degradation rate constants obtained in this study were significantly smaller than pure-culture studies, yet they were comparable to values reported for biofilm systems. The study suggests that CAH removal in wetland plant roots may be comparable to processes within biofilms. This has led us to speculate that the active biomass may be on the root surface as a biofilm. The cisDCE and TCE mass losses due to methane oxidizers in this study offer insight into the role of shallow, vegetated wetlands as an environmental sink for such xenobiotic compounds.

  10. Degradation kinetics and mechanism of aniline by heat-assisted persulfate oxidation

    Institute of Scientific and Technical Information of China (English)

    Xiaofang Xie; Yongqing Zhang; Weilin Huang; Shaobing Huang

    2012-01-01

    Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature,persulfate concentration and pH conditions were examined in batch experiments.The results showed that,the aniline degradation followed pseudo first-order reaction model.Aniline degradation rate increased with increasing temperature or persulfate concentration.In the pH range of 3 to 11,a low aniline degradation rate was obtained at strong acid system (pH 3),while a high degradation rate was achieved at strong alkalinity (pH 11).Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5,7 and 9).Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology.And nitrobenzene,4-4'-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation meehanism of aniline was also tentatively proposed.

  11. The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

    Science.gov (United States)

    Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

    2016-07-01

    In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. PMID:27372125

  12. Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

    International Nuclear Information System (INIS)

    Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments

  13. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  14. Influencing Parameters in the Photocatalytic Degradation of Organic Effluent via Nanometal Oxide Catalyst: A Review

    Directory of Open Access Journals (Sweden)

    A. Gnanaprakasam

    2015-01-01

    Full Text Available This paper aims to review the recent works on the photocatalytic degradation of organic pollutants in the presence of nanophotocatalyst. In this regard the effects of operation parameters which could influence the photocatalytic degradation of organic pollutants (such as catalyst preparation method, initial concentration of organic pollutants, presence of doping, catalyst loading, calcinations temperature, pH, presence of oxidants, UV intensity, temperature, and presence of supports are discussed. Recent research suggests that the parameters mentioned above have great influence on the photocatalytic activity of prepared nanocatalyst. Also, the general mechanism of photocatalytic degradation and some recent synthesis methods are discussed here.

  15. A study on the enhancement of sonochemical degradation of eosin B using other advanced oxidation processes

    OpenAIRE

    Goel, Mukesh; Das, Ashutosh; Ravikumar, K.; ASTHANA, ABHISHEK

    2014-01-01

    Eosin B is a xanthenes dye and is a derivate of fluorescein. The efficacy of sonochemical degradation coupled with other advanced oxidation process (AOP’s) has been studied for eosin B degradation in aqueous solution. The study compares the effects of H2O2 concentration, saturating gas (argon, N2, and O2), temperature and pH (3–11). Furthermore, kinetic comparison and a figure of merit for the electrical energy consumption were carried out for the degradation under combination of different AO...

  16. Degradation of 14C-Carbaryl in soils modified by organic matter oxidation and glucose addition

    International Nuclear Information System (INIS)

    The behaviour of the insecticide carbaryl was studied during eight weeks by means of radiometric techniques in samples of Brunizem and Dark-Red Latosol soils from Parana, Brazil. Groups of oxidized, sterillized and untreated soils with and without glucose additions were incubated with 14C-Carbaryl and analyzed. In both soils, results showed and increase in the degradation rate of carbaryl on oxidized samples whereas adding glucose did not influence its degradation rate. Three metabolites having R sub(f) 0.23,0.40 and 0.70 were detected. (Author)

  17. Oxidative degradation of lignin by photochemical and chemical radical generating systems

    International Nuclear Information System (INIS)

    Oxidation of specifically radiolabeled 14C-lignins by UV/H2O2, Fenton's reagent, photosensitizing riboflavin, UV- and γ-irradiation was examined. In the presence of UV/H2O2, a hydroxyl radical (radicalOH) generating system, 14C-methoxy, 2-[14C-sidechain] and 14C-ring labeled lignin were rapidly and extensively degraded as measured by gel filtration of the reaction products on Sephadex LH-20. This suggested that exposure to radicalOH leads to rapid, nonspecific lignin degradation. Rapid degradation of 14C-methoxy, 2-[14C-sidechain] and 14C-ring labeled lignin also occurred in the presence of the radicalOH generating system, Fenton's reagent, confirming the primary role of radicalOH in these reactions. Photosensitizing riboflavin, also capable of effecting transformation of organic compounds via Type I hydrogen radical abstractions, caused extensive oxidative degradation of 14C-methoxy labeled lignin and significant degradation of 2-[14C-sidechain] and 14C-ring labeled lignin. In addition, UV- and γ-irradiation caused slower but extensive degradation of the polymers, probably via radical type mechanisms. All of these results indicate that radicalOH as well as organic radical generating systems are effective agents for the purpose of degrading this heterogeneous, optically inactive and random biopolymer. (author)

  18. Amoxicillin Oxidative Degradation Synthesized by Nano Zero Valent Iron

    Directory of Open Access Journals (Sweden)

    AR Yazdanbakhsh

    2016-03-01

    Full Text Available Introduction: Amoxicillin is one of the most important groups of pharmaceuticals that benefits humans and animals. However, antibiotics excertion in wastewaters and environment have emerged as a serious risk to the biotic environment, and their toxic effects can harm the organisms. Iron-based metallic nanoparticles have received special attention in regard with remediation of groundwater contaminants. In the typical nZVI-based bimetallic particle system, Fe acts as the reducing agent. Thus, the present study aimed to evaluate the synthesis and characteristics of nZVI in regard with degrading AMX. Methods: In this study, nZVI nanoparticles were synthesized using the liquid-phase reduction method by EDTA as a stabilizer material. Structure and properties of nanoparticles were characterized by BET, SEM, XRD and EDX analysis. A multi-variate analysis was applied using a response surface methodology (RSM in order to develop a quadratic model as a functional relationship between AMX removal efficiency and independent variables ( initial pH values, dosage of nZVI, contact time and amoxicillin concentration. The four independent variables of solution pH (2–10, AMX concentration (5-45mg/l, contact time (5-85 min and nanoparticles dose (0.25 – 1.25 g were transformed to the coded values. Results: The study results demonstrated that more than 69 % of AMX was removed by nZVI. The optimal AMX removal conditions using nZVI were found as 1.25 g of nZVI, pH 4, contact time of 80 min and concentration of 30 mg/l. Conclusions: The ability of nZVI in degradation of AMX revealed that these materials can serve as a potential nano material with respect to the environmental remediation.

  19. Degradation of sodium dodecyl sulphate in water using solar driven Fenton-like advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Bandala, Erick R. [Instituto Mexicano de Tecnologia del Agua, Paseo Cuauhnahuac 8532, Progreso Jiutepec, Morelos 62550 (Mexico)], E-mail: ebandala@tlaloc.imta.mx; Pelaez, Miguel A.; Salgado, Maria J. [Instituto Mexicano de Tecnologia del Agua, Paseo Cuauhnahuac 8532, Progreso Jiutepec, Morelos 62550 (Mexico); Torres, Luis [Instituto de Ingenieria, Universidad Nacional Autonoma de Mexico (UNAM) (Mexico)

    2008-03-01

    Synthetic wastewater samples containing a model surfactant were treated using two different Fenton-like advanced oxidation processes promoted by solar radiation; the photo-Fenton reaction and Co/PMS/UV processes. Comparison between the different experimental conditions was performed by means of the overall surfactant degradation achieved and by obtaining the initial rate in the first 15 min of reaction (IR{sub 15}). It was found that, for dark Fenton reaction, the maximum surfactant degradation achieved was 14% under low iron and oxidant concentration. Increasing Fenton reagents by one magnitude order, surfactant degradation achieved 63% in 60 min. The use of solar radiation improved the reaction rate by 17% under same conditions and an additional increase of 12.5% was obtained by adjusting initial pH to 2. IR{sub 15} values for dark and irradiated Fenton reactions were 0.143 and 0.154 mmol/min, respectively, for similar reaction conditions and this value increased to 0.189 mmol/min when initial pH was adjusted. The use of the Co/PMS system allow us to determine an increase in the degradation rate, for low reaction conditions (1 mM of transition metal; 4 mM oxidant) similar to those used in dark Fenton reaction. Surfactant degradation increased from 3%, for Fenton reaction, to 44.5% in the case of Co/PMS. When solar irradiation was included in the experiments, under same reaction conditions described earlier, surfactant degradation up to 64% was achieved. By increasing Co/PMS reagent concentration by almost 9 times under irradiated conditions, almost complete (>99%) surfactant degradation was reached in 5 min. Comparing IR{sub 15} values for Co/PMS and Co/PMS/UV, it allow us to observe that the use of solar radiation increased the degradation rate in one magnitude order when compared with dark experiments and further increase of reagent concentration increased reaction rate twice.

  20. Oxidative degradation of polybenzimidazole membranes as electrolytes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Liao, J.H.; Li, Qingfeng; Rudbeck, H.C.;

    2011-01-01

    Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper...... the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending...

  1. Combined treatment using chemical oxidation and radiation for enhancement degradation of chitosan

    International Nuclear Information System (INIS)

    Combined treatment using chemical oxidation and radiation has been considered for enhancement of chitosan degradation. The oxidative reagent was chosen to be hydrogen peroxide from heterogeneous reaction. Optimal conditions of concentration, temperature, pH were also determined. Characteristics of chitosan products were investigated by measurements of proton nuclear magnetic resonance spectroscopy (1HNMR), infrared spectroscopy (IR), viscosity average molecular weight (MW), ultraviolet spectrophotometry (UV), thermogravimetry analysis (TGA) and X-ray diffraction (XRD). (author)

  2. Model-based Interpretation of the Performance and Degradation of Reformate Fueled Solid Oxide Fuel Cells

    OpenAIRE

    Kromp, Alexander

    2013-01-01

    Solid oxide fuel cells offer great prospects for the sustainable, clean and safe conversion of various fuels into electrical energy. In this thesis, the performance-determining loss processes for the cell operation on reformate fuels are elucidated via electrochemical impedance spectroscopy. Model-based analyses reveal the electrochemical fuel oxidation mechanism, the coupling of fuel gas transport and reforming chemistry and the impact of fuel impurities on the degradation of each loss process.

  3. Degradation of oxcarbazepine by UV-activated persulfate oxidation: kinetics, mechanisms, and pathways.

    Science.gov (United States)

    Bu, Lingjun; Zhou, Shiqing; Shi, Zhou; Deng, Lin; Li, Guangchao; Yi, Qihang; Gao, Naiyun

    2016-02-01

    The degradation kinetics and mechanism of the antiepileptic drug oxcarbazepine (OXC) by UV-activated persulfate oxidation were investigated in this study. Results showed that UV/persulfate (UV/PS) process appeared to be more effective in degrading OXC than UV or PS alone. The OXC degradation exhibited a pseudo-first order kinetics pattern and the degradation rate constants (k obs) were affected by initial OXC concentration, PS dosage, initial pH, and humic acid concentration to different degrees. It was found that low initial OXC concentration, high persulfate dosage, and initial pH enhanced the OXC degradation. Additionally, the presence of humic acid in the solution could greatly inhibit the degradation of OXC. Moreover, hydroxyl radical (OH•) and sulfate radical (SO4 (-)••) were identified to be responsible for OXC degradation and SO4 (-)• made the predominant contribution in this study. Finally, major intermediate products were identified and a preliminary degradation pathway was proposed. Results demonstrated that UV/PS system is a potential technology to control the water pollution caused by emerging contaminants such as OXC.

  4. Degradation of oxcarbazepine by UV-activated persulfate oxidation: kinetics, mechanisms, and pathways.

    Science.gov (United States)

    Bu, Lingjun; Zhou, Shiqing; Shi, Zhou; Deng, Lin; Li, Guangchao; Yi, Qihang; Gao, Naiyun

    2016-02-01

    The degradation kinetics and mechanism of the antiepileptic drug oxcarbazepine (OXC) by UV-activated persulfate oxidation were investigated in this study. Results showed that UV/persulfate (UV/PS) process appeared to be more effective in degrading OXC than UV or PS alone. The OXC degradation exhibited a pseudo-first order kinetics pattern and the degradation rate constants (k obs) were affected by initial OXC concentration, PS dosage, initial pH, and humic acid concentration to different degrees. It was found that low initial OXC concentration, high persulfate dosage, and initial pH enhanced the OXC degradation. Additionally, the presence of humic acid in the solution could greatly inhibit the degradation of OXC. Moreover, hydroxyl radical (OH•) and sulfate radical (SO4 (-)••) were identified to be responsible for OXC degradation and SO4 (-)• made the predominant contribution in this study. Finally, major intermediate products were identified and a preliminary degradation pathway was proposed. Results demonstrated that UV/PS system is a potential technology to control the water pollution caused by emerging contaminants such as OXC. PMID:26452660

  5. Sequential reduction-oxidation for photocatalytic degradation of tetrabromobisphenol A: Kinetics and intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yaoguang; Lou, Xiaoyi; Xiao, Dongxue; Xu, Lei [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Zhaohui, E-mail: zhaohuiwang@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Liu, Jianshe, E-mail: liujianshe@dhu.edu.cn [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Sequential photocatalytic reduction-oxidation degradation of TBBPA was firstly examined. Black-Right-Pointing-Pointer Different atmospheres were found to have significant effect on debromination reaction. Black-Right-Pointing-Pointer A possible sequential photocatalytic reduction-oxidation pathway was proposed. - Abstract: C-Br bond cleavage is considered as a key step to reduce their toxicities and increase degradation rates for most brominated organic pollutants. Here a sequential reduction/oxidation strategy (i.e. debromination followed by photocatalytic oxidation) for photocatalytic degradation of tetrabromobisphenol A (TBBPA), one of the most frequently used brominated flame retardants, was proposed on the basis of kinetic analysis and intermediates identification. The results demonstrated that the rates of debromination and even photodegradation of TBBPA strongly depended on the atmospheres, initial TBBPA concentrations, pH of the reaction solution, hydrogen donors, and electron acceptors. These kinetic data and byproducts identification obtained by GC-MS measurement indicated that reductive debromination reaction by photo-induced electrons dominated under N{sub 2}-saturated condition, while oxidation reaction by photoexcited holes or hydroxyl radicals played a leading role when air was saturated. It also suggested that the reaction might be further optimized for pretreatment of TBBPA-contaminated wastewater by a two-stage reductive debromination/subsequent oxidative decomposition process in the UV-TiO{sub 2} system by changing the reaction atmospheres.

  6. Zircaloy-oxidation and hydrogen-generation rates in degraded-core accident situations

    International Nuclear Information System (INIS)

    Oxidation of Zircaloy cladding is the primary source of hydrogen generated during a degraded-core accident. In this paper, reported Zircaloy oxidation rates, either measured at 1500 to 18500C or extrapolated from the low-temperature data obtained at 0C, are critically reviewed with respect to their applicability to a degraded-core accident situation in which the high-temperature fuel cladding is likely to be exposed to and oxidized in mixtures of hydrogen and depleted steam, rather than in an unlimited flux of pure steam. New results of Zircaloy oxidation measurements in various mixtures of hydrogen and steam are reported for >15000C. The results show significantly smaller oxidation and, hence, hydrogen-generation rates in the mixture, compared with those obtained in pure steam. It is also shown that a significant fraction of hydrogen, generated as a result of Zircaloy oxidation, is dissolved in the cladding material itself, which prevents that portion of hydrogen from reaching the containment building space. Implications of these findings are discussed in relation to a more realistic method of quantifying the hydrogen source term for a degraded-core accident analysis

  7. SIMULTANEOUS DEGRADATION OF SOME PHTHALATE ESTERS UNDER FENTON AND PHOTO-FENTON OXIDATION PROCESSES

    Directory of Open Access Journals (Sweden)

    BELDEAN-GALEA M.S.

    2015-03-01

    Full Text Available In this study the assessment of the degradation efficiency of five phthalates, DEP, BBP, DEHP, DINP and DIDP, found in a mixture in a liquid phase, using the Fenton and Photo Fenton oxidation processes, was conducted. It was observed that the main parameters that influence the Fenton oxidative processes of phthalates were the concentration of the oxidizing agent, H2O2, the concentration of the catalyst used, Fe2+, the pH value, UV irradiation and the reaction time. For the Fenton oxidative process, the highest degradation efficiencies were 19% for DEP, 50% for BBP, 84% for DEHP, 90% for DINP and 48% for DIDP, when the experiments were carried out using concentrations of 20 mg L-1 phthalate mixture, 100 mg L-1 H2O2, 10 mg L-1 Fe2+ at a pH value of 3, with a total reaction time of 30 minutes. For the Photo-Fenton oxidative process carried out in the same conditions as Fenton oxidative process, it was observed that after an irradiation time of 90 minutes under UV radiation the degradation efficiencies of phthalates were improved, being 22% for DEP, 71% for BBP, 97% for DEHP, 97% for DINP and 81% for DIDP.

  8. Structural basis for cellobiose dehydrogenase action during oxidative cellulose degradation.

    Science.gov (United States)

    Tan, Tien-Chye; Kracher, Daniel; Gandini, Rosaria; Sygmund, Christoph; Kittl, Roman; Haltrich, Dietmar; Hällberg, B Martin; Ludwig, Roland; Divne, Christina

    2015-01-01

    A new paradigm for cellulose depolymerization by fungi focuses on an oxidative mechanism involving cellobiose dehydrogenases (CDH) and copper-dependent lytic polysaccharide monooxygenases (LPMO); however, mechanistic studies have been hampered by the lack of structural information regarding CDH. CDH contains a haem-binding cytochrome (CYT) connected via a flexible linker to a flavin-dependent dehydrogenase (DH). Electrons are generated from cellobiose oxidation catalysed by DH and shuttled via CYT to LPMO. Here we present structural analyses that provide a comprehensive picture of CDH conformers, which govern the electron transfer between redox centres. Using structure-based site-directed mutagenesis, rapid kinetics analysis and molecular docking, we demonstrate that flavin-to-haem interdomain electron transfer (IET) is enabled by a haem propionate group and that rapid IET requires a closed CDH state in which the propionate is tightly enfolded by DH. Following haem reduction, CYT reduces LPMO to initiate oxygen activation at the copper centre and subsequent cellulose depolymerization. PMID:26151670

  9. Structural basis for cellobiose dehydrogenase action during oxidative cellulose degradation

    Science.gov (United States)

    Tan, Tien-Chye; Kracher, Daniel; Gandini, Rosaria; Sygmund, Christoph; Kittl, Roman; Haltrich, Dietmar; Hällberg, B. Martin; Ludwig, Roland; Divne, Christina

    2015-01-01

    A new paradigm for cellulose depolymerization by fungi focuses on an oxidative mechanism involving cellobiose dehydrogenases (CDH) and copper-dependent lytic polysaccharide monooxygenases (LPMO); however, mechanistic studies have been hampered by the lack of structural information regarding CDH. CDH contains a haem-binding cytochrome (CYT) connected via a flexible linker to a flavin-dependent dehydrogenase (DH). Electrons are generated from cellobiose oxidation catalysed by DH and shuttled via CYT to LPMO. Here we present structural analyses that provide a comprehensive picture of CDH conformers, which govern the electron transfer between redox centres. Using structure-based site-directed mutagenesis, rapid kinetics analysis and molecular docking, we demonstrate that flavin-to-haem interdomain electron transfer (IET) is enabled by a haem propionate group and that rapid IET requires a closed CDH state in which the propionate is tightly enfolded by DH. Following haem reduction, CYT reduces LPMO to initiate oxygen activation at the copper centre and subsequent cellulose depolymerization. PMID:26151670

  10. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation

    KAUST Repository

    Zhang, Tao

    2011-11-01

    The cerium supported palladium oxide (PdO/CeO 2) at a low palladium loading was found very effective in catalytic ozonation of oxalate, a probe compound that is difficult to be efficiently degraded in water with hydroxyl radical oxidation and one of the major byproducts in ozonation of organic matter. The oxalate was degraded into CO 2 during the catalytic ozonation. The molar ratio of oxalate degraded to ozone consumption increased with increasing catalyst dose and decreasing ozone dosage and pH under the conditions of this study. The maximum molar ratio reached around 1, meaning that the catalyst was highly active and selective for oxalate degradation in water. The catalytic ozonation, which showed relatively stable activity, does not promote hydroxyl radical generation from ozone. Analysis with ATR-FTIR and in situ Raman spectroscopy revealed that 1) oxalate was adsorbed on CeO 2 of the catalyst forming surface complexes, and 2) O 3 was adsorbed on PdO of the catalyst and further decomposed to surface atomic oxygen (*O), surface peroxide (*O 2), and O 2 gas in sequence. The results indicate that the high activity of the catalyst is related to the synergetic function of PdO and CeO 2 in that the surface atomic oxygen readily reacts with the surface cerium-oxalate complex. This kind of catalytic ozonation would be potentially effective for the degradation of polar refractory organic pollutants and hydrophilic natural organic matter. © 2011 American Chemical Society.

  11. Pathogenic prion protein is degraded by a manganese oxide mineral found in soils

    Science.gov (United States)

    Russo, F.; Johnson, C.J.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

    2009-01-01

    Prions, the aetiological agents of transmissible spongiform encephalopathies, exhibit extreme resistance to degradation. Soil can retain prion infectivity in the environment for years. Reactive soil components may, however, contribute to the inactivation of prions in soil. Members of the birnessite family of manganese oxides (MnO2) rank among the strongest natural oxidants in soils. Here, we report the abiotic degradation of pathogenic prion protein (PrPTSE) by a synthetic analogue of naturally occurring birnessite minerals. Aqueous MnO2 suspensions degraded the PrPTSE as evidenced by decreased immunoreactivity and diminished ability to seed protein misfolding cyclic amplification reactions. Birnessite-mediated PrPTSE degradation increased as a solution's pH decreased, consistent with the pH-dependence of the redox potential of MnO2. Exposure to 5.6 mg MnO2 ml-1 (PrPTSE:MnO2=1 : 110) decreased PrPTSE levels by ???4 orders of magnitude. Manganese oxides may contribute to prion degradation in soil environments rich in these minerals. ?? 2009 SGM.

  12. Anodic oxidation of o-nitrophenol on BDD electrode: Variable effects and mechanisms of degradation

    Energy Technology Data Exchange (ETDEWEB)

    Rabaaoui, Nejmeddine, E-mail: chimie_tunisie@yahoo.fr [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Saad, Mohamed El Khames [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Moussaoui, Younes [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Physical Organic Chemistry Laboratory, Science Faculty of Sfax, University of Sfax (Tunisia); Allagui, Mohamed Salah [Science Faculty of Gafsa, University of Gafsa (Tunisia); Bedoui, Ahmed [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Science Faculty of Gabes, 6072, University of Gabes (Tunisia); Elaloui, Elimame [Materials, Environment and Energy Laboratory (06/UR/12-01), Science Faculty of Gafsa, 2112, University of Gafsa (Tunisia); Science Faculty of Gafsa, University of Gafsa (Tunisia)

    2013-04-15

    Highlights: ► Anodic oxidation is an effective method for degrading o-nitrophenol. ► The effect of operating parameters on the degradation was investigated. ► The main intermediate products were determined by HPLC technique. ► A plausible degradation pathway of o-nitrophenol was proposed. -- Abstract: The electrochemical oxidation of pesticide, o-nitrophenol (ONP) as one kind of pesticide that is potentially dangerous and biorefractory, was studied by galvanostatic electrolysis using boron-doped diamond (BDD) as anode. The influence of several operating parameters, such as applied current density, supporting electrolyte, and initial pH value, was investigated. The best degradation occurred in the presence of Na{sub 2}SO{sub 4} (0.05 M) as conductive electrolyte. After 8 h, nearly complete degradation of o-nitrophenol was achieved (92%) using BDD electrodes at pH 3 and at current density equals 60 mA cm{sup −2}. The decay kinetics of o-nitrophenol follows a pseudo-first-order reaction. Aromatic intermediates such as catechol, resorcinol, 1,2,4-trihydroxybenzene, hydroquinone and benzoquinone and carboxylic acids such as maleic glycolic, malonic, glyoxilic and oxalic, have been identified and followed during the ONP treatment by chromatographic techniques. From these anodic oxidation by-products, a plausible reaction sequence for ONP mineralization on BDD anodes is proposed.

  13. Mesoporous iron–manganese oxides for sulphur mustard and soman degradation

    Energy Technology Data Exchange (ETDEWEB)

    Štengl, Václav, E-mail: stengl@iic.cas.cz [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 Řež (Czech Republic); J.E. Purkyně University in Ústí nad Labem, Faculty of Environment, 400 96 Ústí nad Labem (Czech Republic); Grygar, Tomáš Matys [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 Řež (Czech Republic); J.E. Purkyně University in Ústí nad Labem, Faculty of Environment, 400 96 Ústí nad Labem (Czech Republic); Bludská, Jana [Department of Solid State Chemistry, Institute of Inorganic Chemistry AS CR, v.v.i., 250 68 Řež (Czech Republic); Opluštil, František; Němec, Tomáš [Military Technical Institute of Protection Brno, Veslařská 230, 628 00 Brno (Czech Republic)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► New nanodispersive materials based on Fe and Mn oxides for degradations of warfare agents. ► The best activities for the degradation of sulphur mustard (97.9% in 64 min) and soman (97.9% in 64 min). ► One pot synthesis with friendly transformed to industrial conditions. -- Abstract: Substituted iron(III)–manganese(III, IV) oxides, ammonio-jarosite and birnessite, were prepared by a homogeneous hydrolysis of potassium permanganate and iron(III) sulphate with 2-chloroacetamide and urea, respectively. Synthesised oxides were characterised using Brunauer–Emmett–Teller (BET) surface area and Barrett–Joiner–Halenda porosity (BJH), X-ray diffraction (XRD), infrared spectroscopy (IR), Raman spectroscopy and scanning electron microscopy (SEM). The oxides were taken for an experimental evaluation of their reactivity against sulphur mustard (HD) and soman (GD). When ammonio-jarosite formation is suppressed by adding urea to the reaction mixture, the reaction products are mixtures of goethite, schwertmannite and ferrihydrite, and their degradation activity against soman considerably increases. The best activities for the degradation of sulphur mustard (97.9% in 64 min) and soman (97.9% in 64 min) were observed for FeMn{sub 7}5 with 32.6 wt.% Fe (36.8 wt.% Mn) and FeMn{sub 3}7U with 60.8 wt.% Fe (10.1 wt.% Mn) samples, respectively.

  14. Oxidative Degradation of 4-chlorophenol in Aqueous Induced by Plasma with Submersed Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The oxidative degradation of 4-chlorophenol (4-CP) in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography (HPLC).Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe2+ were examined.The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation.

  15. Novel photocatalysis oxidation system UV/Fe2+/air to degrade 4-CP wastewater

    Institute of Scientific and Technical Information of China (English)

    DU Yingxun; ZHOU Minghua; LEI Lecheng

    2005-01-01

    This paper reported the degradation of 4-CP wastewater by a novel photocatalysis oxidation system--UV/Fe2+/air system, in which air was used as a cheap oxidant that reacted with the excitation state of organics to form H2O2 under the UV light. The formed H2O2 reacted with the added ferrous ion to form Fenton reaction and led to the quick degradation of organic pollutants. It was found that 4-CP could be completely removed within 40 min. The degradation of 4-CP in the UV/Fe2+/air system was superior to the conventional UV/Fenton system (the initial concentration of H2O2 was 22 mg-L-1). UV/Fe2+/air is an effective and cheap method for treatment of the organics that can be excited by UV light.

  16. Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

    Science.gov (United States)

    Dang, Trung-Dung; Banerjee, Arghya Narayan; Tran, Quang-Tung; Roy, Sudipta

    2016-11-01

    By a simple wet-chemical procedure using a permanganate in the acidic medium, diatomite coated with amorphous manganese oxide nanoparticles was synthesized. The structural, microstructural and morphological characterizations of the as-synthesized catalysts confirmed the nanostructure of MnO2 and its stabilization on the support - diatomite. The highly efficient and rapid degradation of methylene blue and methyl orange over synthesized MnO2 coated Diatomite has been carried out. The results revealed considerably faster degradation of the dyes against the previously reported data. The proposed mechanism of the dye-degradation is considered to be a combinatorial effect of chemical, physicochemical and physical processes. Therefore, the fabricated catalysts have potential application in waste water treatment, and pollution degradation for environmental remediation.

  17. Studies on degradation of glyphosate by several oxidative chemical processes: ozonation, photolysis and heterogeneous photocatalysis.

    Science.gov (United States)

    Assalin, Marcia R; De Moraes, Sandra G; Queiroz, Sonia C N; Ferracini, Vera L; Duran, Nelson

    2010-01-01

    Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO(2) as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O(3)/pH 10 process was 1.8 minutes.

  18. Functionalization of Liquid Natural Rubber via Oxidative Degradation of Natural Rubber

    Directory of Open Access Journals (Sweden)

    Suhawati Ibrahim

    2014-12-01

    Full Text Available Natural rubber (NR is a high molecular weight natural polymer and can be degraded to liquid natural rubber (LNR leaving certain functional groups at the end of chains. In this study, LNR samples prepared via oxidative degradation using H2O2 and NaNO2 as reagents were found to have different end groups depending on the pH of the reaction medium. In an acidic medium, LNR with hydroxyl terminal groups was formed as the degradation reaction was initiated by hydroxyl radicals produced from decomposition of peroxynitrite acid. In contrast, a redox reaction took place in an alkaline medium to yield LNR with carbonyl terminal groups. The mechanisms of reaction are discussed and proposed to explain the formation of different end groups when reaction carried out in acidic and alkaline media. Chain degradation in an acidic medium seems to be more effective than in an alkaline medium, and thus yields LNR with lower Mn.

  19. Electrochemical detection of benzo(a)pyrene and related DNA damage using DNA/hemin/nafion–graphene biosensor

    International Nuclear Information System (INIS)

    Graphical abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed to quantitatively study the DNA damage induced by the metabolite of benzo(a)pyrene in the presence of H2O2. - Highlights: • Construction of a novel DNA/hemin/nafion-graphene/GCE biosensor. • DNA damage induced by the benzo(a)pyrene metabolite was detected. • DPV analysis of benzo(a)pyrene provided a quantitative estimate of DNA damage. • Hemin/H2O2 system could mimic the cytochrome P450 to metabolize benzo(a)pyrene. - Abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed for the analysis of the benzo(a)pyrene PAH, which can produce DNA damage induced by a benzo(a)pyrene (BaP) enzyme-catalytic product. This biosensor was assembled layer-by-layer, and was characterized with the use of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy. Ultimately, it was demonstrated that the hemin/nafion–graphene/GCE was a viable platform for the immobilization of DNA. This DNA biosensor was treated separately in benzo(a)pyrene, hydrogen peroxide (H2O2) and in their mixture, respectively, and differential pulse voltammetry (DPV) analysis showed that an oxidation peak was apparent after the electrode was immersed in H2O2. Such experiments indicated that in the presence of H2O2, hemin could mimic cytochrome P450 to metabolize benzo(a)pyrene, and a voltammogram of its metabolite was recorded. The DNA damage induced by this metabolite was also detected by electrochemical impedance and ultraviolet spectroscopy. Finally, a novel, indirect DPV analytical method for BaP in aqueous solution was developed based on the linear metabolite versus BaP concentration plot; this method provided a new, indirect, quantitative estimate of DNA damage

  20. Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

    Directory of Open Access Journals (Sweden)

    Subas K. Muduli

    2014-04-01

    Full Text Available A facile, solvothermal synthesis of mesoporous cerium oxide nanospheres is reported for the purpose of the photocatalytic degradation of organic dyes and future applications in sustainable energy research. The earth-abundant, relatively affordable, mixed valence cerium oxide sample, which consists of predominantly Ce7O12, has been characterized by powder X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy, and transmission electron microscopy. Together with N2 sorption experiments, the data confirms that the new cerium oxide material is mesoporous and absorbs visible light. The photocatalytic degradation of rhodamin B is investigated with a series of radical scavengers, suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species.

  1. Degradation of 4-aminophenol by hydrogen peroxide oxidation using enzyme from Serratia marcescens as catalyst

    Institute of Scientific and Technical Information of China (English)

    SUN Min; YAO Risheng; YOU Yahua; DENG Shengsong; GAO Wenxia

    2007-01-01

    This paper reports on the degradation of 4-aminophenol using hydrogen peroxide as oxidizer and the enzyme from Serratia marcescens AB 90027 as catalyst.The effecting factors during degradation and the degrading mechanism were studied.Also,the location of the enzyme in the cell,which could catalyze the degradation of 4-aminophenol,was analyzed.The results showed that to degrade 50 mL of 4-aminophenol whose concentration was 500 mg/L,the optimal conditions were:volume of H2O2=3 mL,temperature=40-60℃ and pH=9-10]In the degradation process,4-aminophenol was first converted to benzo quinone and NH3,then organic acids including maleic acid,fumaleic acid,and oxalic acid were formed,and then finally CO2 and H2O were generated as final products.The enzyme that could catalyze the degradation of 4-aminophenol was mainly extracellular enzyme.

  2. EFFECTS OF FUNGI ON CO-METABOLIC DEGRADATION OF BENZO[a]PYRENE IN PADDY SOIL%真菌对污染水稻土中苯并[a]芘共代谢降解研究

    Institute of Scientific and Technical Information of China (English)

    刘世亮; 骆永明; 吴龙华; 曹志洪

    2011-01-01

    在恒温和恒定转速培养条件下,模拟生物泥浆反应器法,选择从石油污染土壤中分离出来的青霉菌、黑曲霉、白腐真菌等3种真菌,在添加不同浓度菲和邻苯二甲酸作为共存底物情况下,研究其对水稻土中苯并[a]芘(B[a]P)的共代谢降解.结果表明,未灭菌土壤对B[a]P有降解能力.当土壤中添加菲时,提高了B[a]P在土壤中的降解率,100 mg kg-1浓度菲处理的降解率显著高于200 mg kg-1浓度菲处理,邻苯二甲酸对B[a]P降解影响不大.灭菌土壤中的B[a]P几乎没有降解.添加菲及邻苯二甲酸均促进了青霉菌对B[a]P的降解,其中菲浓度为100 mg kg-1处理效果最显著.与灭菌土壤相比,接种黑曲霉提高了B[a]P的降解率,但添加菲与邻苯二甲酸却均抑制了黑曲霉菌对B[a]P的降解.白腐真菌能有效地降解B[a]P,但高浓度菲抑制了白腐真菌对B[a]P的降解,同时邻苯二甲酸对促进白腐真菌降解B[a]P的效果不明显.%Simulated bioslurry remediation of PAHs contaminated soil was carried out. Three strains of fungi isolated from petroleum-contaminated soils were inoculated into paddy soils different in application rate of phenanthrene and phthalic acid, to investigate their effects of co-metabolic degradation of B [ a] P therein. Results show that in natural soils,some native microorganisms were able to degrade B [ a] P and addition of low molecular weight PAHs-phenanthrene increased, degradation rate of B [ a ] P in the soil. The effect was greater when the application rate of phenanthrene was 100 mg kg-1 than when it was 200 mg kg-1. But the addition of phthalic acid did not show much effect. In sterilized soils, degradation of B[ a] P in soils was hardly observed. However, inoculation of Penicillium stimulated degradation of B[ a] P in all the three treatments, i.e. phenanthrene at 100 mg kg-1 , phenanthrene at 200 mg kgand phthalic acid, but only in the treatment of phenanthrene at 100 mg kg-1the

  3. Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

    International Nuclear Information System (INIS)

    Nanostructured TiO2 and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m2 g−1. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures. Undoped TiO2 and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH3O from TMP at room temperature and 100 °C. Cleavage of CH3O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP

  4. Oxidative degradation of endotoxin by advanced oxidation process (O3/H2O2 & UV/H2O2).

    Science.gov (United States)

    Oh, Byung-Taek; Seo, Young-Suk; Sudhakar, Dega; Choe, Ji-Hyun; Lee, Sang-Myeong; Park, Youn-Jong; Cho, Min

    2014-08-30

    The presence of endotoxin in water environments may pose a serious public health hazard. We investigated the effectiveness of advanced oxidative processes (AOP: O3/H2O2 and UV/H2O2) in the oxidative degradation of endotoxin. In addition, we measured the release of endotoxin from Escherichia coli following typical disinfection methods, such as chlorine, ozone alone and UV, and compared it with the use of AOPs. Finally, we tested the AOP-treated samples in their ability to induce tumor necrosis factor alpha (TNF-α) in mouse peritoneal macrophages. The production of hydroxyl radical in AOPs showed superior ability to degrade endotoxin in buffered solution, as well as water samples from Korean water treatment facilities, with the ozone/H2O2 being more efficient compared to UV/H2O2. In addition, the AOPs proved effective not only in eliminating E. coli in the samples, but also in endotoxin degradation, while the standard disinfection methods lead to the release of endotoxin following the bacteria destruction. Furthermore, in the experiments with macrophages, the AOPs-deactivated endotoxin lead to the smallest induction of TNF-α, which shows the loss of inflammation activity, compared to ozone treatment alone. In conclusion, these results suggest that AOPs offer an effective and mild method for endotoxin degradation in the water systems.

  5. Degradable Molybdenum Oxide Nanosheets with Rapid Clearance and Efficient Tumor Homing Capabilities as a Therapeutic Nanoplatform.

    Science.gov (United States)

    Song, Guosheng; Hao, Jiali; Liang, Chao; Liu, Teng; Gao, Min; Cheng, Liang; Hu, Junqing; Liu, Zhuang

    2016-02-01

    Molybdenum oxide (MoOx) nanosheets with high near-infrared (NIR) absorbance and pH-dependent oxidative degradation properties were synthesized, functionalized with polyethylene glycol (PEG), and then used as a degradable photothermal agent and drug carrier. The nanosheets, which are relatively stable under acidic pH, could be degraded at physiological pH. Therefore, MoOx-PEG distributed in organs upon intravenous injection would be rapidly degraded and excreted without apparent in vivo toxicity. MoOx-PEG shows efficient accumulation in tumors, the acidic pH of which then leads to longer tumor retention of those nanosheets. Along with the capability of acting as a photothermal agent for effective tumor ablation, MoOx-PEG can load therapeutic molecules with high efficiencies. This concept of inorganic theranostic nanoagent should be relatively stable in tumors to allow imaging and treatment, while being readily degradable in normal organs to enable rapid excretion and avoid long-term retention/toxicity.

  6. Degradation of endocrine disruptor bisphenol A in drinking water by ozone oxidation

    Institute of Scientific and Technical Information of China (English)

    XU Bin; GAO Naiyun; RUI Min; WANG Hong; WU Haihui

    2007-01-01

    The ozone oxidation of endocrine disruptor bisphenol A in drinking water was investigated.A stainless completely mixed reactor was employed to carry out the degradation experiments by means of a batch model.With an initial concentration of 11.0 mg/L,the removal efficiencies of BPA (bisphenol A) could be measured up to 70%,82%,and 90% when the dosages of ozone were 1,1.5,and 2 mg/L,respectively.The impacts on BPA degradation under the conditions of different ozone dosages,water background values,BPA initial concentrations,and ozone adding time were analyzed.The results showed that ozone dosage plays a dominant role during the process of BPA degradation,while the impact of the contact time could be ignored.UV wavelength scanning was used to confirm that the by-products were produced,which could be absorbed at UV254.The value of UV254 was observed to have changed during the ozonation process.Based on the change of UV254,it could be concluded that BPA is not completely degraded at low ozone dosage,while shorter adding time of total ozone dosage,high ozone dosage,and improvement of dissolved ozone concentration greatly contribute to the extent of BPA degradation.The effects of applied H2O2 dose in ozone oxidation of BPA were also examined in this study.The O3-H2O2 processes proved to have similar effects on the degradation of BPA by ozone oxidation.

  7. Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Li; Tang, Jia; Wang, Yueqiang; Hu, Min; Zhou, Shungui, E-mail: sgzhou@soil.gd.cn

    2015-08-15

    Highlights: • Paddy soil contaminated with benzoate incubated with hematite and magnetite. • Iron oxides addition enhanced methanogenic benzoate degradation by 25–53%. • The facilitated syntrophy might involve direct interspecies electron transfer. • Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved. - Abstract: Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH{sub 4} production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

  8. Thermal Treatment of Cerium Oxide and Its Properties: Adsorption Ability versus Degradation Efficiency

    Directory of Open Access Journals (Sweden)

    Pavel Janoš

    2014-01-01

    Full Text Available Cerium oxide belongs to the most important heterogeneous catalysts, but its applicability as so-called reactive sorbent for the degradation of toxic chemicals was only recently discovered. For these purposes, cerium oxide is prepared by precipitation of insoluble cerium salts (carbonates with a subsequent thermal decomposition. Properties of cerium oxide prepared from the carbonate precursor are strongly affected by the temperature during the calcination. Main physicochemical properties of cerium oxide (specific surface area, crystallinity, and surface chemistry were examined in dependence on the calcination temperature. As the adsorptive properties of CeO2 are undoubtedly of great importance in the abovementioned applications, the adsorption ability was studied using an azo dye Acid Orange 7 (AO7 as a model compound. The highest sorption efficiency towards AO7 exhibited sorbents prepared at temperatures below 700°C, which was attributed mainly to the presence of hydroxyl groups on the oxide surface. A strong correlation was found between an adsorption efficiency of cerium oxides and their degradation efficiency for organophosphate pesticide parathion methyl. The >Ce–OH groups on the sorbent surface are responsible for the dye binding by the surface-complexation mechanism, and probably also for the nucleophilic cleavage of the P–O–aryl bond in the pesticide molecule.

  9. Transition metal oxide loaded MCM catalysts for photocatalytic degradation of dyes

    Indian Academy of Sciences (India)

    Divya Jyothi; Parag A Deshpande; B R Venugopal; Srinivasan Chandrasekaran; Giridhar Madras

    2012-03-01

    Transition metal oxide (TiO2, Fe2O3, CoO) loaded MCM-41 and MCM-48 were synthesized by a two-step surfactant-based process. Nanoporous, high surface area compounds were obtained after calcination of the compounds. The catalysts were characterized by SEM, XRD, XPS, UV-vis and BET surface area analysis. The catalysts showed high activity for the photocatalytic degradation of both anionic and cationic dyes. The degradation of the dyes was described using Langmuir-Hinshelwood kinetics and the associated rate parameters were determined.

  10. Ubiquitination of inducible nitric oxide synthase is required for its degradation

    Science.gov (United States)

    Kolodziejski, Pawel J.; Musial, Aleksandra; Koo, Ja-Seok; Eissa, N. Tony

    2002-01-01

    Inducible nitric oxide synthase (iNOS) is responsible for nitric oxide (NO) synthesis from l-arginine in response to inflammatory mediators. We have previously shown that iNOS is degraded through the 26S proteasome. Targeting of proteins for proteasomal degradation may or may not require their covalent linkage to multiubiquitin chains (ubiquitination). In addition, ubiquitination of a protein can serve functions other than signaling proteolysis. In this context, it is not known whether iNOS is subject to ubiquitination or whether ubiquitination is required for its degradation. In this study, we show that iNOS, expressed in HEK293 cells or induced in primary bronchial epithelial cells, A549 cells, or murine macrophages, is subject to ubiquitination. To investigate whether iNOS ubiquitination is required for its degradation, HEK293T cells were cotransfected with plasmids containing cDNAs of human iNOS and of the dominant negative ubiquitin mutant K48R. Disruption of ubiquitination by K48R ubiquitin resulted in inhibition of iNOS degradation. ts20 is a mutant cell line that contains a thermolabile ubiquitin-activating enzyme (E1) that is inactivated at elevated temperature, preventing ubiquitination. Incubation of ts20 cells, stably expressing human iNOS, at the nonpermissive temperature (40°C) resulted in inhibition of iNOS degradation and marked accumulation of iNOS. These studies indicate that iNOS is subject to ubiquitination and that ubiquitination is required for its degradation. PMID:12221289

  11. COMPARISON OF DIFFERENT ADVANCED OXIDATION PROCESSES DEGRADING P-CHLOROPHENOL IN AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    H. Movahedyan ، A. M. Seid Mohammadi ، A. Assadi

    2009-07-01

    Full Text Available In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H2O2, microwave/H2O2 and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation rate were pH=7 and H2O2 concentration of 0.05 mol/L for ultraviolet/H2O2 system and pH=10.5, H2O2 concentration of about 0.1 mol/L and microwave irradiation power of about 600W for microwave/H2O2 system at constant p-chlorophenol concentration. The degradation of p-chlorophenol by different types of oxidation processes followed first order rate decay kinetics. The rate constants were 0.137, 0.012, 0.02 and 0.004/min1 for ultraviolet/H2O2, microwave/H2O2, ultraviolet and microwave irradiation alone. Finally a comparison of the specific energy consumption showed that ultraviolet/H2O2 process reduced the energy consumption by at least 67% compared with the microwave/H2O2 process.

  12. Fracturing Fluid (Guar Polymer Gel Degradation Study by using Oxidative and Enzyme Breaker

    Directory of Open Access Journals (Sweden)

    Aung Kyaw

    2012-06-01

    Full Text Available Oxidative and enzyme breakers are used in this research project with the main objective to study on the degradation pattern of fracturing fluid (i.e., guar polymer gel as a function of time, temperature and breaker concentration itself. The fracturing fluid used in hydraulic fracturing or frac pack contain a chemical breakers to reduce the viscosity of the fluid intermingled with the proppant. Chemical breakers reduce viscosity of the guar polymer by cleaving the polymer into small-molecular-weight fragments. The reduction of viscosity will facilitate the flow-back of residual polymer providing rapid recovery of polymer from proppant pack. Ineffective breakers or misapplication of breakers can result in screen-outs or flow-back of viscous fluids both of which can significantly decrease the well productivity. Breaker activity of low to medium temperature range oxidative and enzyme breaker systems was evaluated. ViCon NF an oxidative breaker (Halliburton product and GBW 12- CD an enzyme breaker (BJ Services product were used in this research project with the main objective to study on the degradation pattern of fracturing fluid (guar polymer gel as a function of (time, temperature and breaker concentration itself. This study provides focuses on the way to mix the fracturing fluid, compositions of the fracturing fluid and how to conduct the crosslink and break test. Crosslink test indicate the optimum cross-linker concentration to produce good crosslink gel and the break test gave the characteristic of the gel during degradation process and also the break time. Besides relying on the laboratory experiment, information obtained from research on SPE and US Pattern papers were used to make a comparison study on oxidative and enzyme breakers properties. Degradation pattern observed from the break test showed that reduction in gel viscosity depends on time, temperature and breaker concentration. Observations from experiment also revealed that small

  13. A reactor system combining reductive dechloirnation with cometabolic oxidation for complete degradation of tetrachloroentylene

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A laboratory sequential anaerobic-aerobic bioreactor system,which consisted of an anaerobic fixed film reactor and twoaerobic chemostats, was set up to degrade tetrachloroethylene (PCE)without accumulating highly toxic degradation intermediates. A soil(ca. 150 mg/liter) of PCE stoichiometrically intocis-1,2-dichloroethylene (cis-DCE), was attached to ceramic mediain the anaerobic fixed film reactor. A phenol degrading strain,Alcaligenes sp. R5, which can efficiently degrade cis-DCE byco-metabolic oxidation, was used as inoculum for the aerobicchemostats consisted of a transformation reactor and a growthreactor. The anaerobic fixed film bioreactor showed more than 99 %of PCE transformation into cis-DCE in the range of influent PCE48h. On the other hand, efficient degradation of the resultantcis-DCE by strain R5 in the following aerobic system could not beachieved due to oxygen limitation. However, 54% of the maximum(H2O2) was supplemented to the transformation reactor as anadditional oxygen source. Further studies are needed to achievemore efficient co-metabolic degradation of cis-DCE in the aerobic reactor.

  14. Protective effects of baicalein and wogonin against benzo[a]pyrene- and aflatoxin B(1)-induced genotoxicities.

    Science.gov (United States)

    Ueng, Y F; Shyu, C C; Liu, T Y; Oda, Y; Lin, Y L; Liao, J F; Chen, C F

    2001-12-15

    To evaluate the protective effects of baicalein and wogonin against benzo[a]pyrene- and aflatoxin (AF) B(1)-induced toxicities, the effects of these flavonoids on the genotoxicities and oxidation of benzo[a]pyrene and AFB(1) were studied in C57BL/6J mice. Baicalein and wogonin reduced benzo[a]pyrene and AFB(1) genotoxicities as monitored by the umuC gene expression response in Salmonella typhimurium TA1535/pSK1002. Baicalein added in vitro decreased liver microsomal benzo[a]pyrene hydroxylation (AHH) activity with an ic(50) of 33.9 +/- 1.4 microM at 100 microM benzo[a]pyrene. Baicalein also inhibited AFQ(1) and AFB(1)-epoxide formation from AFB(1) (50 microM) oxidation (AFO) with ic(50) values of 22.8 +/- 1.4 and 5.3 +/- 0.8 microM, respectively. However, the in vitro inhibitory effects of wogonin on AHH and AFO activities in liver microsomes were less than those of baicalein as inhibition by 500 microM wogonin was only about 51-65%. Treatment of mice with liquid diets containing 5 mM baicalein and wogonin resulted in 22 and 49% decreases in hepatic AHH activities, respectively. Baicalein treatment resulted in 39 and 32% decreases in AFQ(1) and AFB(1)-epoxide formation from liver microsomal AFO, respectively. Wogonin treatment resulted in 39 and 47% decreases in AFQ(1) and AFB(1)-epoxide formation, respectively. A 1-week pretreatment with wogonin significantly decreased hepatic DNA adduct formation in mice treated with 200 mg/kg of benzo[a]pyrene via gastrogavage. These in vitro and in vivo effects suggested that baicalein and wogonin might have beneficial effects against benzo[a]pyrene- and AFB(1)-induced hepatic toxicities and that wogonin had a stronger protective effect in vivo. PMID:11755119

  15. Effects of benzo(a)pyrene exposure on oxidative stress and ATPase in the hippocampus of rats%苯并[a]芘对大鼠海马组织氧化应激及ATP酶的影响

    Institute of Scientific and Technical Information of China (English)

    段利; 汤艳; 陈承志; 彭斌; 邱崇莹; 戚友宾; 涂白杰

    2013-01-01

    目的 通过研究苯并[a]芘(B[a]P)对大鼠行为学、海马氧化应激及ATP酶的影响,探讨B[a]P的神经行为毒性分子机制.方法 将120只21d龄雄性SD大鼠,随机分为空白对照组、植物油组(溶剂对照组),2.5、5.0、10.0 mg/kg B[a]P染毒组,每组24只.腹腔注射给药,每天1次,连续4周.染毒结束后,用Morris水迷宫和穿梭箱检测学习记忆能力;用化学比色法测定海马超氧化物歧化酶(SOD)、Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶的活力及丙二醛(MDA)含量;用荧光标记方法测定海马Ca2+浓度.结果 各染毒组大鼠的水迷宫逃避潜伏期、穿梭箱主动回避反应潜伏期(AARL)和被动回避反应潜伏期(RARL)均明显高于空白对照组和溶剂对照组,水迷宫末次跨平台次数和穿梭箱主动回避反应次数(AARF)均明显低于空白对照组和溶剂对照组,差异均有统计学意义(P<0.05);且呈剂量-效应关系.与空白对照组和溶剂对照组比较,染毒组大鼠海马组织SOD活力、Na+-K+-ATP酶和ca2+-Mg2+-ATP酶活力明显下降,且呈剂量-效应关系,差异均有统计学意义(P<0.05).染毒组大鼠海马组织MDA含量、Ca2+浓度均明显高于空白对照组和溶剂对照组,且呈剂量-效应关系,差异均有统计学意义(P<0.05).结论 B[a]P所致神经行为毒性,可能与染毒后大鼠海马组织氧化应激受损,Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活力下降有关.%Objective To investigate the effects of benzo[a]pyrene (B[a]P) exposure on the behaviors and hippocampal oxidative stress and ATPase in rats and the molecular mechanism of neurobehavioral toxicity of B[a]P.Methods A total of 120 male SD rats (21 days old) were randomly and equally assigned to five groups:blank control group,vegetable oil (solvent control) group,and 2.5,5,and 10 mg/kg B[a]P exposure groups.The rats in B [a]P exposure groups were injected intraperitoneally with B[a]P once a day for 4 consecutive weeks.Then,Morris water maze and

  16. Modeling the competitive effect of ammonium oxidizers and heterotrophs on the degradation of MTBE in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A mathematical model was used to study effects on the degradation of methyl tert-butyl ether (MTBE) in a packed bed reactor due to the presence of contaminants such as ammonium, and the mix of benzene, toluene, ethylbenzene and xylenes (BTEX). It was shown that competition between the slower...... growing MTBE degraders and the co-contaminant oxidizers prevented MTBE's degradation when oxygen was limited. In this event, the co-contaminant oxidizers out-competed the MTBE degraders in the reactor's biofilm. However, if the oxygen supply was sufficient, MTBE would be fully degraded after the zone...... where the co-contaminants were oxidized. The results of the model further indicate that contradicting findings in the literature about the effects of BTEX on the degradation of MTBE are mainly due to differences in the study methodologies. Effects such as short-term toxicity of BTEX and the lack...

  17. Investigation of oxidative degradation and non‐enzymatic browning reactions in krill and fish oils

    DEFF Research Database (Denmark)

    Thomsen, Birgitte Raagaard; Haugsgjerd, Bjørn Ole; Griinari, Mikko;

    2013-01-01

    of these classical methods. Nevertheless, the conclusion was supported by the results of the Oxipres™ measurements, which showed that the oxygen consumption was higher for fish oil. Furthermore, the level of most volatile lipid oxidation products was higher for fish oil. The development of Strecker degradation......The aim of this research was to investigate the oxidation progress and pathways of krill and fish oil during 21 days of incubation at 40°C. The oxidative stability of the oils was investigated through: (i) classical methods such as peroxide value (PV), anisidine value (AV), thiobarbituric reactive...... conditions using the Oxipres™ at 90°C. The results from analysis of PV, AV, TBARS, conjugated dienes and trienes, and the antioxidant content suggested that krill oil was more oxidatively stable than fish oil. However, the color or other constituents of the krill oil might affect the result...

  18. Formation and degradation of valuable intermediate products during wet oxidation of municipal sludge.

    Science.gov (United States)

    Baroutian, Saeid; Gapes, Daniel J; Sarmah, Ajit K; Farid, Mohammed M; Young, Brent R

    2016-04-01

    The current study investigated the formation of organic acids and alcohols as major intermediate products of wet oxidation of municipal sludge. Municipal sludge was subjected to 60-min wet oxidation at temperatures ranging from 220 to 240°C, with 20bar oxygen partial pressure. Acetic acid was the main intermediate compound produced in this study, followed by propionic, n-butyric, iso-butyric and pentanoic acids and methanol. It was found that the process severity has a significant influence on the formation and degradation of these intermediate products. PMID:26832394

  19. Stability of 6:2 fluorotelomer sulfonate in advanced oxidation processes: degradation kinetics and pathway.

    Science.gov (United States)

    Yang, Xiaoling; Huang, Jun; Zhang, Kunlun; Yu, Gang; Deng, Shubo; Wang, Bin

    2014-03-01

    Perfluorooctane sulfonate (PFOS), a widely used mist suppressant in hard chrome electroplating industry, has been listed in the Stockholm Convention for global ban. 6:2 Fluorotelomer sulfonate (6:2 FTS) acid and salts have been adopted as alternative products in the market, but no data about their abiotic degradation has been reported. In the present study, the degradability of 6:2 FTS potassium salt (6:2 FTS-K) was evaluated under various advanced oxidation processes, including ultraviolet (UV) irradiation, UV with hydrogen peroxide (H2O2), alkaline ozonation (O3, pH = 11), peroxone (O3/H2O2), and Fenton reagent oxidation (Fe(2+)/H2O2). UV/H2O2 was found to be the most effective approach, where the degradation of 6:2 FTS-K followed the pseudo-first-order kinetics. The intermediates were mainly shorter chain perfluoroalkyl carboxylic acid (C7 to C2), while sulfate (SO4 (2-)) and fluoride (F(-)) were found to be the final products. The high yields of SO4 (2-) and F(-) indicate that 6:2 FTS-K can be nearly completely desulfonated and defluorinated under UV/H2O2 condition. The degradation should firstly begin with the substitution of hydrogen atom by hydroxyl radicals, followed by desulfonation, carboxylation, and sequential "flake off" of CF2 unit. Compared with PFOS which is inert in most advanced oxidation processes, 6:2 FTS-K is more degradable as the alternative.

  20. Enzymatic Degradation of Oxidized and Reduced Graphene Nanoribbons by Lignin Peroxidase.

    Science.gov (United States)

    Lalwani, Gaurav; Xing, Weiliang; Sitharaman, Balaji

    2014-10-01

    The expanding use of graphene for various industrial and biomedical applications requires efficient remediation strategies during their disposal into waste streams. Additionally, the interactions of graphene with the biota need thorough evaluation. In this study, we investigated the interactions of oxidized and reduced graphene oxide nanoribbons (GONRs and rGONRs) with lignin peroxidase (LiP), a ligninolytic enzyme released from white rot fungus. GONRs and rGONRs were treated with LiP in the presence and absence of veratryl alcohol (VA; an electron transfer mediator and secondary metabolite of white rot fungi). Transmission electron microscopy showed the formation of large defects (holes) in the graphene sheet, which increased in diameter with increased degradation time. Raman spectroscopic analysis indicated that, within 96 hours, in the presence of hydrogen peroxide and VA, the GONRs and rGONRs were completely and partially degraded by LiP, respectively. Comparisons between groups with or without VA showed that degradation of GONRs was accelerated in the presence of VA. These results indicated that LiP could efficiently degrade GONRs and rGONRs in the presence of VA, suggesting that VA may be an essential factor needed to degrade rGONRs via LiP treatment. Thus, the wide presence of white rot fungi, and thereby LiP, in nature, could lead to efficient degradation of graphene present in the environment. Additionally, LiP, which has a higher theoretical redox potential compared to horseradish peroxidases and myeloperoxidases, could be a better candidate for the environmental remediation of graphene.

  1. Degradation of acid red 14 by silver ion-catalyzed peroxydisulfate oxidation in an aqueous solution

    OpenAIRE

    RASOULIFARD, Mohammad Hossein; MOHAMMADI, Seied Mohammad Mahdi DOUST

    2012-01-01

    Silver ion (Ag1+)-catalyzed peroxydisulfate was studied for the degradation of acid red 14 (AR-14) in an aqueous medium. The effect of different parameters, such as temperature, peroxydisulfate concentration, and dye and Ag1+ concentrations, were investigated. Application of Ag1+-catalyzed peroxydisulfate, as an advanced oxidation process, introduces an effectual method for wastewater treatment. An accelerated reaction using S2O82- to destroy dyes can be achieved via chemical activat...

  2. Degradation of p-nitrotoluene by 03/H2 02 process and oxidation mechanism

    Institute of Scientific and Technical Information of China (English)

    YU Ying-hui; MA Jun; HOU Yan-jun; GAO Jin-sheng

    2009-01-01

    The degradation of p-nitrotoluene by O2/H2O2 process in a bubble contact column was investigated.Effects of the molar ratio of hydrogen peroxide to ozone, pH value and t-butanol on the oxidation process were discussed. It was found that the proper H2 O2/O3 molar ratio for the degradation of p-nitrotoluene was around O. 6, different pH values and the presence of t-butanol highly influenced the removal efficiency of p-nitrotoluene. 5-metbyl-2-nitrophenol, 2-methy1-5-nitrophenol, (4-nitrophenyl) methanol, 5-(hydroxymethyl) -2-nitro phenol, acetic acid, 2-methylpropanc diacid and 2-(hydroxylmethyl) propane diacid were identified as degradation intermediates and products through GC-MS. Radical reaction mechanism and degradation pathway were proposed based on the results of experiments. It is deduced that the benzene ring of p-nitrotoluene can be only destroyed by hydroxyl radicals through a polyhydrexy intermediate pathway. Then unstable polybydroxy intermediates can be oxidized to different acids with low molecular weight rapidly.

  3. The degradation of lining of rotary furnaces in the production of zinc oxide

    Directory of Open Access Journals (Sweden)

    Natália Luptáková

    2014-06-01

    Full Text Available This paper is closely connected with the complex problem of degradation relating to the refractories of rotary furnace linings in the production of zinc oxide. Zinc oxide can be produced by variety of ways, but the most common method of production which is used in Europe is indirect, i.e. pyrolytic combustion of zinc. This method is also called "French process" of manufacturing ZnO. But this mentioned method of preparation leads to the creation of the enormous amount of zinc slag including chemical complexes of elements Fe, Zn and Al. The mechanism of degradation of the lining leads to slag rests and it is closely connected with the mutual interaction of the aggressive agents with the components of the lining. This process creates a new undesired surface layer which increased the overall thickness of zinc slag. Stuck slag has the influence on rapid degradation of the linings and moreover it also decreases the production quality of ZnO. Analysis results introduced in this paper are significant information for minimizing of degradation of rotary furnaces.  

  4. Mechanism and Kinetics Study for Photocatalytic Oxidation Degradation: A Case Study for Phenoxyacetic Acid Organic Pollutant

    Directory of Open Access Journals (Sweden)

    Kian Mun Lee

    2015-01-01

    Full Text Available Photocatalysis is a rapidly expanding technology for wastewater treatment, including a wide range of organic pollutants. Thus, understanding the kinetics and mechanism of the photocatalytic oxidation (PCO for degradation of phenoxyacetic acid (PAA is an indispensable component of risk assessment. In this study, we demonstrated that the central composite design (CCD coupled with response surface methodology (RSM was successfully employed to probe the kinetics and mechanism of PCO degradation for PAA using an efficient zinc oxide (ZnO photocatalyst. In our current case study, four independent factors such as ZnO dosage, initial concentration of PAA, solution pH, and reaction time on the PCO degradation for PAA were examined in detail. Based on our results obtained from RSM analyses, an efficient pathway leading to the high degradation rate (>90% was applying 0.4 g/L of ZnO dosage with 16 mg/L of concentration of PAA at pH 6.73 for 40 minutes. The experimental results were fitted well with the derived response model with R2 = 0.9922. This study offers a cost-effective way for probing our global environmental water pollution issue.

  5. Degradation/oxidation susceptibility of organic photovoltaic cells in aqueous solutions.

    Science.gov (United States)

    Habib, K; Husain, A; Al-Hazza, A

    2015-12-01

    A criterion of the degradation/oxidation susceptibility of organic photovoltaic (OPV) cells in aqueous solutions was proposed for the first time. The criterion was derived based on calculating the limit of the ratio value of the polarization resistance of an OPV cell in aqueous solution (Rp(s)) to the polarization resistance of the OPV cell in air (Rp(air)). In other words, the criterion lim(Rp(s)/Rp(air)) = 1 was applied to determine the degradation/oxidation of the OPV cell in the aqueous solution when Rp(air) became equal (increased) to Rp(s) as a function of time of the exposure of the OPV cell to the aqueous solution. This criterion was not only used to determine the degradation/oxidation of different OPV cells in a simulated operational environment but also it was used to determine the electrochemical behavior of OPV cells in deionized water and a polluted water with fine particles of sand. The values of Rp(s) were determined by the electrochemical impedance spectroscopy at low frequency. In addition, the criterion can be applied under diverse test conditions with a predetermined period of OPV operations.

  6. The role of oxidation and enzymatic hydrolysis on the in vivo degradation of trimethylene carbonate based photocrosslinkable elastomers.

    Science.gov (United States)

    Chapanian, Rafi; Tse, M Yat; Pang, Stephen C; Amsden, Brian G

    2009-01-01

    The in vivo degradation of trimethylene carbonate (TMC) containing elastomers was investigated, and the mechanism of degradation explored through in vitro degradation under enzymatic and oxidative conditions. The elastomers were prepared via UV initiated crosslinking of prepolymers of TMC and equimolar amounts of TMC and epsilon-caprolactone (CL). The degradation process was followed by investigating the changes in the mechanical properties, mass loss, water uptake, sol content, differential scanning calorimetry, and surface chemistry through attenuated total reflectance infrared (ATR-FTIR) spectroscopy. During in vivo degradation, TMC and TMCCL elastomers exhibited surface erosion. The tissue response was of greater intensity in the case of the TMC elastomer. Both elastomers exhibited degradation in cholesterol esterase containing solutions in vitro, but no parallels were found between the rate of in vivo degradation and the rate of in vitro degradation. Only the TMCCL elastomer degraded in lipase. Degradation in a stable superoxide anion in vitro medium was consistent with the observed in vivo degradation results, indicating a dominant role of oxidation through the secretion of this reactive oxygen species by adherent phagocytic cells in the degradation of these elastomers. PMID:18947866

  7. Catalytic Potential of Nano-Magnesium Oxide on Degradation of Humic Acids From Aquatic Solutions

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-12-01

    Full Text Available Catalytic ozonation is a new and promising process used to remove the contaminants from drinking water and wastewater. This study aimed to evaluate the catalytic potential of nano-magnesium oxide (nano-MgO for the removal of humic acids (HA from water. Mg (NO32 solution was used to prepare MgO powder by the calcination method. In a semi-batch reactor, the catalytic ozonation was carried out. The effects of the various operating parameters, including pH, reaction time, T-butyl alcohol (TBA and phosphate on HA degradation were evaluated. Experimental results indicated that degradation of HA was increased as the pH solution and reaction time were increased. Maximum HA degradation was obtained at pH = 10 and the reaction time of 10 minutes in the catalytic process. The calculated catalytic potential of nano-MgO on ozonation of HA was 60%. Moreover, catalytic ozonation process was not affected by TBA and the main reaction on HA degradation HA have effect take place on MgO surface. According to the results of this study, the developed MgO catalyst is the active and proficient catalyst in HA degradation using the catalytic ozonation process.

  8. Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

    Directory of Open Access Journals (Sweden)

    Jamal Al-Sabahi

    2016-03-01

    Full Text Available Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

  9. Diclofenac and 2-anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver.

    Science.gov (United States)

    Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

    2012-05-01

    The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio-MnOx), biogenic silver nanoparticles (Bio-Ag(0)) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2-anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio-MnOx, Bio-Ag(0) and Ag(+) separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio-MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese-free P. putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co-metabolic removal during active Mn(2+) oxidation by P. putida; (ii) a synergistic interaction between preoxidized Bio-MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P. putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

  10. Diclofenac and 2‐anilinophenylacetate degradation by combined activity of biogenic manganese oxides and silver

    Science.gov (United States)

    Meerburg, Francis; Hennebel, Tom; Vanhaecke, Lynn; Verstraete, Willy; Boon, Nico

    2012-01-01

    Summary The occurrence of a range of recalcitrant organic micropollutants in our aquatic environment has led to the development of various tertiary wastewater treatment methods. In this study, biogenic manganese oxides (Bio‐MnOx), biogenic silver nanoparticles (Bio‐Ag0) and ionic silver were used for the oxidative removal of the frequently encountered drug diclofenac and its dechlorinated form, 2‐anilinophenylacetate (APA). Diclofenac was rapidly degraded during ongoing manganese oxidation by Pseudomonas putida MnB6. Furthermore, whereas preoxidized Bio‐MnOx, Bio‐Ag0 and Ag+ separately did not show any removal capacity for diclofenac, an enhanced removal occurred when Bio‐MnOx and silver species were combined. Similar results were obtained for APA. Finally, a slow removal of diclofenac but more rapid APA degradation was observed when silver was added to manganese‐free P. putida biomass. Combining these results, three mechanisms of diclofenac and APA removal could be distinguished: (i) a co‐metabolic removal during active Mn2+ oxidation by P. putida; (ii) a synergistic interaction between preoxidized Bio‐MnOx and silver species; and (iii) a (bio)chemical process by biomass enriched with silver catalysts. This paper demonstrates the use of P. putida for water treatment purposes and is the first report of the application of silver combined with biogenic manganese for the removal of organic water contaminants. PMID:22221449

  11. Degradation mechanism of 2,4,6-trinitrotoluene in supercritical water oxidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The 2,4,6-trinitrotoluene (TNT) is a potential carcinogens and TNT contaminated wastewater, which could not be effectively disposed with conventional treatments. The supercritical water oxidation (SCWO) to treat TNT contaminated wastewater was studied in this article. The TNT concentration in wastewater was measured by high-performance liquid chromatograph (HPLC) and the degraded intermediates were analyzed using GC-MS. The results showed that SCWO could degrade TNT efficiently with O2. The reaction temperature, pressure, residence time and oxygen excess were the main contributing factors in the process. The decomposition of TNT was accelerated as the temperature or residence time increases. At 550℃, 24 MPa, 120 s and oxygen excess 300%, TNT removal rate could exceed 99.9%. Partial oxidation occurs in SCWO without oxygen. It was concluded that supercritical water was a good solvent and had excellent oxidation capability in the existence of oxygen. The main intermediates of TNT during SCWO include toluene, 1,3,5-trinitrobenzene, nitrophenol, naphthalene, fluorenone, dibutyl phthalate, alkanes and several dimers based on the intermediate analysis. Some side reactions, such as coupled reaction, hydrolysis reaction and isomerization reaction may take place simultaneously as TNT is oxidized by SCWO.

  12. Oxidation of rhizosphere sediments by Alternanthera philoxeroides : roots to quicker petroleum degradation?

    International Nuclear Information System (INIS)

    Environments contaminated with organic compounds and metals can be treated using an emerging technology based on phytoremediation. The oxidation of surficial sediments through plant roots is an important feature of phytoremediation, but there is very little data available on this subject. A geochemical study conducted at the San Jacinto Wetland Research Facility (SJWRF) in Texas has shown that Alternanthera philoxeroides is a particular plant that provides oxygen to sediments. Densely vegetated areas generally exhibit redox potentials from 100 to 350 mV and are more oxidized than sparsely vegetated areas where redox potentials are often less than 0 mV. In addition, phytoremediation can accelerate bioremediation of organic compounds in surface soils by releasing enzymes and sugars that catalyze degradation or raise microbial activity. The study examined the oxidation of the rhizosphere in saturated environments such as shoreline remediation projects where oxygen is generally limited. The rate of petroleum degradation observed in studies conducted in the intertidal zone of the SJWRF is comparable to rates that have been computed for other studies, suggesting that rhizosphere has a great capacity to oxidize natural organic matter in addition to petroleum hydrocarbons. 33 refs., 2 tabs., 4 figs

  13. H2 O2-induced higher order chromatin degradation: A novel mechanism of oxidative genotoxicity

    Indian Academy of Sciences (India)

    Gregory W Konat

    2003-02-01

    The genotoxicity of reactive oxygen species (ROS) is well established. The underlying mechanism involves oxidation of DNA by ROS. However, we have recently shown that hydrogen peroxide (H2O2), the major mediator of oxidative stress, can also cause genomic damage indirectly. Thus, H2O2 at pathologically relevant concentrations rapidly induces higher order chromatin degradation (HOCD), i.e. enzymatic excision of chromatin loops and their oligomers at matrix-attachment regions. The activation of endonuclease that catalyzes HOCD is a signalling event triggered specifically by H2O2. The activation is not mediated by an influx of calcium ions, but resting concentrations of intracellular calcium ions are required for the maintenance of the endonuclease in an active form. Although H2O2-induced HOCD can efficiently dismantle the genome leading to cell death, under sublethal oxidative stress conditions H2O2-induced HOCD may be the major source of somatic mutations.

  14. Oxidative Stress in Fungi: Its Function in Signal Transduction, Interaction with Plant Hosts, and Lignocellulose Degradation

    Directory of Open Access Journals (Sweden)

    Michael Breitenbach

    2015-04-01

    Full Text Available In this review article, we want to present an overview of oxidative stress in fungal cells in relation to signal transduction, interaction of fungi with plant hosts, and lignocellulose degradation. We will discuss external oxidative stress which may occur through the interaction with other microorganisms or plant hosts as well as internally generated oxidative stress, which can for instance originate from NADPH oxidases or “leaky” mitochondria and may be modulated by the peroxiredoxin system or by protein disulfide isomerases thus contributing to redox signaling. Analyzing redox signaling in fungi with the tools of molecular genetics is presently only in its beginning. However, it is already clear that redox signaling in fungal cells often is linked to cell differentiation (like the formation of perithecia, virulence (in plant pathogens, hyphal growth and the successful passage through the stationary phase.

  15. Oxidative stress in fungi: its function in signal transduction, interaction with plant hosts, and lignocellulose degradation.

    Science.gov (United States)

    Breitenbach, Michael; Weber, Manuela; Rinnerthaler, Mark; Karl, Thomas; Breitenbach-Koller, Lore

    2015-01-01

    In this review article, we want to present an overview of oxidative stress in fungal cells in relation to signal transduction, interaction of fungi with plant hosts, and lignocellulose degradation. We will discuss external oxidative stress which may occur through the interaction with other microorganisms or plant hosts as well as internally generated oxidative stress, which can for instance originate from NADPH oxidases or "leaky" mitochondria and may be modulated by the peroxiredoxin system or by protein disulfide isomerases thus contributing to redox signaling. Analyzing redox signaling in fungi with the tools of molecular genetics is presently only in its beginning. However, it is already clear that redox signaling in fungal cells often is linked to cell differentiation (like the formation of perithecia), virulence (in plant pathogens), hyphal growth and the successful passage through the stationary phase. PMID:25854186

  16. Natural manganese oxides as catalysts for oxidative coupling of methane: a structural and degradation study

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, L.M.; Bosch, P.; Viveros, T.; Sanchez, H.; Borodko, Y.G. [Universidad Autonoma Metropolitana-Iztapalapa, Mexico (Mexico). Dept. of Chem.

    1997-12-01

    Natural manganese oxides were evaluated as oxidative coupling catalysts to convert methane into C{sub 2}-hydrocarbons. Reactions were done in a cyclic redox mode in which the oxidized catalyst was reacted with methane at 850 C in the absence of oxygen. The bulk and surface analyses (XRD, XPS, FT-IR) indicate that the catalyst deactivation in the methane atmosphere is related to reduction of manganese ions, oxygen depletion of the catalyst surface and formation of manganese carbide species. It is proposed that the XPS line of O1s electrons, Eb=528.6 eV should be assigned to the surface oxygen bound to the reduced Mn{sup 2+} cation with close oxygen vacancies, and lines ofMn2p{sub 3/2} electrons, Eb=641 eV and C1s at 282.5 eV may be assigned to the surface manganese carbide. (orig.) 27 refs.

  17. Thermal degradation studies of LDPE containing cobalt stearate as pro-oxidant

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available The influence of a typical prooxidative additive, cobalt stearate, on the thermal stability, degradation kinetics and lifetime of low-density polyethylene (LDPE was investigated using non-isothermal thermogravimetric analysis (TGA in both nitrogen and air atmosphere. The derivative thermogravimetric (DTG curves indicate single stage and multistage decomposition process in nitrogen and air atmosphere respectively. The kinetic parameters of degradation were evaluated using the Flynn–Wall-Ozawa iso-conversion technique. The apparent activation energies for decomposition have been calculated for degradation under nitrogen atmosphere. The lifetime of LDPE (time for 5% mass loss was estimated to be 8.2·1026 min in nitrogen and was found to decrease dramatically with increase in the concentration of cobalt stearate thereby revealing its pro-oxidative ability. Studies indicated that the service/process temperature also has a strong influence on the lifetime of all the formulations investigated. The effect of cobalt stearate on the air oven aging behavior of LDPE at two different temperatures (70°C and 100°C was also investigated to demonstrate the pro-oxidative nature of cobalt stearate.

  18. Influence of tiopronin, captopril and levamisole therapeutics on the oxidative degradation of hyaluronan.

    Science.gov (United States)

    Valachová, Katarína; Baňasová, Mária; Topoľská, Dominika; Sasinková, Vlasta; Juránek, Ivo; Collins, Maurice N; Šoltés, Ladislav

    2015-12-10

    The ability to protect hyaluronic acid (HA) from oxidative degradation by cupric ions and ascorbate (production of (•)OH and peroxy-type radicals) during acute phase joint inflammation has been investigated using the following drugs: tiopronin, captopril, and levamisole. Radical scavenging activity, i.e. the propensity for donation of electrons was assessed for the drugs by ABTS and DPPH assays. The kinetics of HA degradation have been measured in the presence of each drug using rotational viscometry. The results of ABTS and DPPH assays show the highest radical scavenging activity for captopril, followed by tiopronin. For levamisole, no effect was observed. Captopril and tiopronin prevented HA degradation induced by (•)OH radicals in a similar manner, while tiopronin was more effective in scavenging peroxy-type radicals. On the other hand, levamisole was shown to be a pro-oxidant. Recovered HA fragments were characterized using FT-IR analysis, the incorporation of a sulphur atom from captopril and tiopronin but not from levamisole into the HA molecule was demonstrated.

  19. Highly efficient degradation of 4-nitrophenol over the catalyst of Mn2O3/AC by microwave catalytic oxidation degradation method.

    Science.gov (United States)

    Yin, Cheng; Cai, Jinjun; Gao, Lingfei; Yin, Jingya; Zhou, Jicheng

    2016-03-15

    A new microwave catalytic oxidation process based on two kinds of catalysts, the commercially available activated carbon (AC) and Mn2O3 nanoparticle modified AC (Mn2O3/AC), was reported for the degradation of 4-nitrophenol (4-NP) without adding any oxidant. Effects of microwave power, catalyst dosage, irradiation time, and initial concentration for the degradation efficiency were studied. Results indicated that catalyst of Mn2O3/AC showed much higher catalytic activity than pure AC and Mn2O3 particles. Significantly, 4-NP degradation efficiency reached 99.6%, corresponding to 93.5% TOC removal under optimal conditions with microwave power of 400W, Mn2O3/AC dosage of 2g, reaction time of 5min, and initial concentration of 100mg/L. Hydroxyl radicals (OH) generated during catalytic reaction is the main oxidant, and O2 can not effectively improve removal rate. We proposed the microwave 'photoelectric effect' to interpret the generation of OH in view that microwave irradiation can directly excite the catalyst to produce electron-hole pairs and then transform H2O into OH on the surface of catalyst in solution. The obtained kinetic equation for microwave catalytic oxidation degradation of 4-NP was in line with pseudo-first-order kinetic model, that is, apparent rate constant increased as microwave power density increase.

  20. Oxidative degradation of triazine- and sulfonylurea-based herbicides using Fe(VI): The case study of atrazine and iodosulfuron with kinetics and degradation products

    Science.gov (United States)

    The occurrence of common herbicides (Atrazine, ATZ and Iodosufuron, IDS), in waters presents potential risk to human and ecological health. The oxidative degradation of ATZ and IDS by ferrate(VI) (FeVIO42-, Fe(VI)) is studied at different pH levels where kinetically observed se...

  1. Environmental degradation of oxidation resistant and thermal barrier coatings for fuel-flexible gas turbine applications

    Science.gov (United States)

    Mohan, Prabhakar

    The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air ingestion. The presence of vanadium, sulfur, phosphorus, sodium and calcium impurities in alternative fuels warrants a clear understanding of high-temperature materials degradation for the development of fuel-flexible gas turbine engines. Degradation due to CMAS is a critical problem for gas turbine components operating in a dust-laden environment. In this study, high-temperature degradation due to aggressive deposits such as V2O5, P2O 5, Na2SO4, NaVO3, CaSO4 and a laboratory-synthesized CMAS sand for free-standing air plasma sprayed (APS) yttria stabilized zirconia (YSZ), the topcoat of the TBC system, and APS CoNiCrAlY, the bond coat of the TBC system or a stand-alone ORC, is examined. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study demonstrated that the V2O5 melt degrades the APS YSZ through the formation of ZrV2O7 and YVO 4 at temperatures below 747°C and above 747°C, respectively. Formation of YVO4 leads to the depletion of the Y2O 3 stabilizer and the deleterious transformation of the YSZ to the monoclinic ZrO2 phase. The investigation on the YSZ degradation by Na 2SO4 and a Na2SO4 + V2

  2. Wet oxidative degradation of cellulosic wastes 5- chemical and thermal properties of the final waste forms

    International Nuclear Information System (INIS)

    In this study, the residual solution arising from the wet oxidative degradation of solid organic cellulosic materials, as one of the component of radioactive solid wastes, using hydrogen peroxide as oxidant. Were incorporated into ordinary Portland cement matrix. Leaching as well as thermal characterizations of the final solidified waste forms were evaluated to meet the final disposal requirements. Factors, such as the amount of the residual solution incorporated, types of leachant. Release of different radionuclides and freezing-thaw treatment, that may affect the leaching characterization. Were studied systematically from the data obtained, it was found that the final solid waste from containing 35% residual solution in tap water is higher than that in ground water or sea water. Based on the data obtained from thermal analysis, it could be concluded that incorporating the residual solution form the wet oxidative degradation of cellulosic materials has no negative effect on the hydration of cement materials and consequently on the thermal stability of the final solid waste from during the disposal process

  3. Repeated oxidative degradation of methyl orange through bio-electro-Fenton in bioelectrochemical system (BES).

    Science.gov (United States)

    Ling, Ting; Huang, Bin; Zhao, Mingxing; Yan, Qun; Shen, Wei

    2016-03-01

    Composite Fe2O3/ACF electrode facilitated methyl orange (MO) oxidative degradation using bio-electro-Fenton in bioelectrochemical system (BES) was investigated. Characterized by both XPS and FT-IR techniques, it was found that the composite Fe2O3/ACF electrode with highest Fe loading capacity of 11.02% could be prepared after the carbon felt was oxidized with nitric acid. Moreover, hydrogen peroxide production reached steadily at 88.63 μmol/L with the external resistance as 100 Ω, cathodic aeration rate at 750 mL/min, and the pH of the bio-electro-Fenton system adjusted to 2. Significantly, not only the electrochemical profiles of the BES reactor as electrochemical impedance spectroscopy (EIS) was bettered, but the MO oxidative degradation could be accomplished for eight repeated batches, with the MO removal efficiency varied slightly from 73.9% to 86.7%. It indicated that the bio-electro-Fenton might be a promising eco-friendly AOP method for Azo-dye wastewater treatment. PMID:26722807

  4. Microwave-assisted chemical oxidation of biological waste sludge: simultaneous micropollutant degradation and sludge solubilization.

    Science.gov (United States)

    Bilgin Oncu, Nalan; Akmehmet Balcioglu, Isil

    2013-10-01

    Microwave-assisted hydrogen peroxide (MW/H2O2) treatment and microwave-assisted persulfate (MW/S2O8(2-)) treatment of biological waste sludge were compared in terms of simultaneous antibiotic degradation and sludge solubilization. A 2(3) full factorial design was utilized to evaluate the influences of temperature, oxidant dose, and holding time on the efficiency of these processes. Although both MW/H2O2 and MW/S2O8(2-) yielded ≥97% antibiotic degradation with 1.2g H2O2 and 0.87 g S2O8(2-) per gram total solids, respectively, at 160 °C in 15 min, MW/S2O8(2-) was found to be more promising for efficient sludge treatment at a lower temperature and a lower oxidant dosage, as it allows more effective activation of persulfate to produce the SO4(-) radical. Relative to MW/H2O2, MW/S2O8(2-) gives 48% more overall metal solubilization, twofold higher improvement in dewaterability, and the oxidation of solubilized ammonia to nitrate in a shorter treatment period. PMID:23928124

  5. Protecting BOPP film from UV degradation with an atomic layer deposited titanium oxide surface coating

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, Kimmo, E-mail: kimmo.lahtinen@lut.fi [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Maydannik, Philipp; Seppänen, Tarja; Cameron, David C. [ASTRaL, Lappeenranta University of Technology, Mikkeli (Finland); Johansson, Petri; Kotkamo, Sami; Kuusipalo, Jurkka [Paper Converting and Packaging Technology, Tampere University of Technology, Tampere (Finland)

    2013-10-01

    Titanium oxide layers were deposited onto a BOPP film by atomic layer deposition in order to prevent UV degradation of the film. The coatings were deposited in a low-temperature process at 80 °C by using tetrakis(dimethylamido)titanium and ozone as titanium and oxygen precursors, respectively. UV block characteristics of the coatings and their effect on the polymer were measured by using UV–vis and IR spectrometry, and differential scanning calorimetry. According to the results, the coatings provided a considerable decrease in the photodegradation of the BOPP film during UV exposure. IR spectra showed that during a 6-week UV exposure, a 67 nm titanium oxide coating was able to almost completely prevent the formation of photodegradation products in the film. The mechanical properties of the film were also protected by the coating, but as opposed to what the IR study suggested they were still somewhat compromised by the UV light. After a 6-week exposure, the tensile strength and elongation at break of the 67 nm titanium oxide coated film decreased to half of the values measured before the treatment. This should be compared to the complete degradation suffered by the uncoated base sheet already after only 4 weeks of treatment. The results show that nanometre scale inorganic films deposited by ALD show a promising performance as effective UV protection for BOPP substrates.

  6. Hydrogen peroxide generation by the Weissberger biogenic oxidative system during hyaluronan degradation.

    Science.gov (United States)

    Valachová, Katarina; Topoľská, Dominika; Mendichi, Raniero; Collins, Maurice N; Sasinková, Vlasta; Šoltés, Ladislav

    2016-09-01

    By applying the enzyme catalase, our study on hyaluronan degradation confirms the generation of hydrogen peroxide using the Weissberger biogenic oxidative system (WBOS), which is composed of ascorbate and cupric ions. Dynamic viscosities of hyaluronan (HA) solutions influenced by WBOS in the absence and presence of catalase were analysed by rotational viscometry. Molar masses of HAs were determined by size-exclusion chromatography with multi-angle laser-light scattering. Our results show that catalase dose-dependently inhibited the degradation of HA macromolecules, which presumably confirms the generation of H2O2 in the reaction system. This has implications in range of biomedical applications such as arthritic joint treatment, tissue engineering, ocular and cosmetic surgery. PMID:27185130

  7. Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Štengl, Václav, E-mail: stengl@iic.cas.cz; Henych, Jiří; Grygar, Tomáš; Pérez, Raúl

    2015-01-15

    Nanostructured TiO{sub 2} and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m{sup 2} g{sup −1}. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures. Undoped TiO{sub 2} and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH{sub 3}O from TMP at room temperature and 100 °C. Cleavage of CH{sub 3}O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP.

  8. Structure and photocatalysis activity of silver doped titanium oxide nanotubes array for degradation of pollutants

    Science.gov (United States)

    Al-Arfaj, E. A.

    2013-10-01

    Semiconductor titanium oxide showed a wonderful performance as a photocatalysis for environmental remediation. Owing to high stability and promising physicochemical properties, titanium oxide nanostructures are used in various applications such as wastewater treatment, antimicrobial and air purification. In the present study, titanium oxide nanotubes and silver doped titanium oxide nanotubes were synthesized via anodic oxidation method. The morphology and composition structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results depicted that nanotubes possess anatase phase with average tube diameter of 65 nm and 230 ± 12 nm in length. The band gap of the un-doped and silver doped titanium dioxide nanotubes was determined using UV-Vis. spectrophotometer. The results showed that the band gap of titanium dioxide nanotubes is decreased when doped with silver ions. The photocatalysis activity of un-doped and silver doped TiO2 nanotubes were evaluated in terms of degradation of phenol in the presence of ultra violet irradiation. It was found that silver doped TiO2 nanotubes exhibited much higher photocatalysis activity than un-doped TiO2 nanotubes.

  9. Highly efficient visible light mediated azo dye degradation through barium titanate decorated reduced graphene oxide sheets

    Science.gov (United States)

    Rastogi, Monisha; Kushwaha, H. S.; Vaish, Rahul

    2016-03-01

    This study investigates BaTiO3 decorated reduced graphene oxide sheets as a potential visible light active catalyst for dye degradation (Rhodamine B). The composites were prepared through conventional hydrothermal synthesis technique using hydrazine as a reducing agent. A number of techniques have been employed to affirm the morphology, composition and photocatalytic properties of the composites; these include UV-visible spectrophotoscopy that assisted in quantifying the concentration difference of Rhodamine B. The phase homogeneity of the composites was examined through x-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) was employed to confirm the orientation of the BaTiO3 particles over the reduced graphene oxide sheets. Photoluminescence (PL) emission spectra assisted in determining the surface structure and excited state of the catalyst. Fourier transformed-infrared (FTIR) spectra investigated the vibrations and adsorption peak of the composites, thereby ascertaining the formation of reduced graphene oxide. In addition, diffuse reflectance spectroscopy (DRS) demonstrated an enhanced absorption in the visible region. The experimental investigations revealed that graphene oxide acted as charge collector and simultaneously facilitated surface adsorption and photo-sensitization. It could be deduced that BaTiO3-reduced graphene oxide composites are of significant interest the field of water purification through solar photocatalysis. [Figure not available: see fulltext.

  10. Variability in oxidative degradation of charcoal: Influence of production conditions and environmental exposure

    Science.gov (United States)

    Ascough, P. L.; Bird, M. I.; Francis, S. M.; Thornton, B.; Midwood, A. J.; Scott, A. C.; Apperley, D.

    2011-05-01

    Charcoal is a key component of the Black Carbon (BC) continuum, where BC is characterized as a recalcitrant, fire-derived, polyaromatic material. Charcoal is an important source of palaeoenvironmental data, and of great interest as a potential carbon sink, due to its high apparent environmental stability. However, at least some forms of charcoal are clearly susceptible to environmental alteration and degradation over relatively short timescales. Although these processes have importance for the role of charcoal in global biogeochemistry, they remain poorly understood. Here we present results of an investigation into the susceptibility of a range of charcoal samples to oxidative degradation in acidified potassium dichromate. The study examines both freshly-produced charcoal, and charcoal exposed to environmental conditions for up to 50,000 years. We compare the proportion of carbon present in different forms between the samples, specifically with respect to the relative chemical resistance of these forms. This was undertaken in order to improve understanding of the post-depositional diagenetic changes affecting charcoal within environmental deposits. A wide range in chemical compositions are apparent both within and between the sample groups. In freshly-produced charcoal, material produced at 300 °C contains carbon with more labile forms than charcoal produced at ⩾400 °C, signifying a key chemical change over the 300-400 °C temperature range. Charcoal exposed to environmental depositional conditions is frequently composed of a highly carboxylated aromatic structure and contains a range of carbon fractions of varying oxidative resistance. These findings suggest that a significant number of the environmental charcoals have undergone post-depositional diagenetic alteration. Further, the data highlight the potential for the use of controlled progressive oxidative degradation as a method to characterize chemical differences between individual charcoal samples.

  11. Iron-Doped Titania Nanoparticles for the Photocatalytic Oxidative Degradation of Nitrite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Iron-doped titania nanoparticles exhibit a higher photocatalytic activity than pure TiO2 for the degradation of nitrite. The optimum Fe-doped content in terms of activity is approximately 0. 5 %. The increase in photoactivity is probably due to the higher adsorption and the inhibition of electron-hole recombination. The photocatalytic oxidation reaction of nitrite over the Fe-doped TiO2 catalyst follows zero-order kinetics, which is different from that over pure TiO2. The reaction rate decreases linearly with the increase of the pH of the solution.

  12. A random-effects model for long-term degradation analysis of solid oxide fuel cells

    International Nuclear Information System (INIS)

    Solid oxide fuel cells (SOFCs) are electrochemical devices converting the chemical energy into electricity with high efficiency and low pollutant emissions. Tough very promising, this technology is still in a developing phase, and degradation at the cell/stack level with operating time is still an issue of major concern. Methods to directly observe degradation modes and to measure their evolution over time are difficult to implement, and indirect performance indicators are adopted, typically related to voltage measurements in long-term tests. In order to describe long-term degradation tests, three components of the voltage measurements should be modelled: the smooth decay of voltage over time for each single unit; the variability of voltage decay among units; and the high-frequency small fluctuations of voltage due to experimental noise and lack of fit. In this paper, we propose an empirical random-effects regression model of polynomial type enabling to evaluate separately these three types of variability. Point and interval estimates are also derived for some performance measures, such as the mean voltage, the prediction of cell voltage, the reliability function and the cell-to-cell variability in SOFC stacks. Finally, the proposed methodology is applied to two real case-studies of long-term degradation tests of SOFC stacks. - Highlights: • We propose an empirical random-effects model for SOFC cells voltage in long runs. • Some SOFC performance and manufacturing quality measures are derived. • An application to two real case-studies of long-term degradation tests is provided. • The reliability function of SOFCs and its lower confidence limit are computed

  13. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U.J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A.M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  14. Use of Advanced Oxidation and Aerobic Degradation for Remediation of Various Hydrocarbon Contaminates

    Energy Technology Data Exchange (ETDEWEB)

    Paul Fallgren

    2009-03-06

    Western Research Institute in conjunction with Sierra West Consultants, Inc., Tetra Tech, Inc., and the U.S. Department of Energy conducted laboratory and field studies to test different approaches to enhance degradation of hydrocarbons and associated contaminants. WRI in conjunction with Sierra West Consultants, Inc., conducted a laboratory and field study for using ozone to treat a site contaminated with MTBE and other hydrocarbons. Results from this study demonstrate that a TOD test can be used to resolve the O{sub 3} dosage problem by establishing a site-specific benchmark dosage for field ozone applications. The follow-up testing of the laboratory samples provided indications that intrinsic biodegradation could be stimulated by adding oxygen. Laboratory studies also suggests that O3 dosage in the full-scale field implementation could be dialed lower than stoichiometrically designed to eliminate the formation of Cr(VI). WRI conducted a study involving a series of different ISCO oxidant applications to diesel-contaminated soil and determined the effects on enhancing biodegradation to degrade the residual hydrocarbons. Soils treated with permanganate followed by nutrients and with persulfate followed by nutrients resulted in the largest decrease in TPH. The possible intermediates and conditions formed from NOM and TPH oxidation by permanganate and activated persulfate favors microbial TPH degrading activity. A 'passive-oxidation' method using microbial fuel cell (MFC) technology was conducted by WRI in conjunction with Tetra Tech, Inc., to degrade MTBE in groundwater. These experiments have demonstrated that a working MFC (i.e., one generating power) could be established in the laboratory using contaminated site water or buffered media inoculated with site water and spiked with MTBE, benzene, or toluene. Electrochemical methods were studied by WRI with goal of utilizing low voltage and amperage electrical sources for 'geo-oxidation' of organic

  15. Comparison of various advanced oxidation processes for the degradation of phenylurea herbicides.

    Science.gov (United States)

    Kovács, Krisztina; Farkas, János; Veréb, Gábor; Arany, Eszter; Simon, Gergő; Schrantz, Krisztina; Dombi, András; Hernádi, Klára; Alapi, Tünde

    2016-01-01

    Various types of advanced oxidation processes (AOPs), such as UV photolysis, ozonation, heterogeneous photocatalysis and their combinations were comparatively examined at the same energy input in a home-made reactor. The oxidative transformations of the phenylurea herbicides fenuron, monuron and diuron were investigated. The initial rates of transformation demonstrated that UV photolysis was highly efficient in the cases of diuron and monuron. Ozonation proved to be much more effective in the transformation of fenuron than in those of the chlorine containing monuron and diuron. In heterogeneous photocatalysis, the rate of decomposition decreased with increase of the number of chlorine atoms in the target molecule. Addition of ozone to UV-irradiated solutions and/or TiO2-containing suspensions markedly increased the initial rates of degradation. Dehalogenation of monuron and diuron showed that each of these procedures is suitable for the simultaneous removal of chlorinated pesticides and their chlorinated intermediates. Heterogeneous photocatalysis was found to be effective in the mineralization.

  16. Kinetics and pathways of ibuprofen degradation by the UV/chlorine advanced oxidation process.

    Science.gov (United States)

    Xiang, Yingying; Fang, Jingyun; Shang, Chii

    2016-03-01

    The UV/chlorine advanced oxidation process (AOP), which forms reactive species such as hydroxyl radicals (HO) and reactive chlorine species (RCS) such as chlorine atoms (Cl) and Cl2(-), is being considered as an alternative to the UV/H2O2 AOP for the degradation of emerging contaminants. This study investigated the kinetics and pathways of the degradation of a recalcitrant pharmaceutical and personal care product (PPCP)-ibuprofen (IBP)-by the UV/chlorine AOP. The degradation of IBP followed the pseudo first-order kinetics. The first-order rate constant was 3.3 times higher in the UV/chlorine AOP than in the UV/H2O2 AOP for a given chemical molar dosage at pH 6. The first-order rate constant decreased from 3.1 × 10(-3) s(-1) to 5.5 × 10(-4) s(-1) with increasing pH from 6 to 9. Both HO and RCS contributed to the degradation, and the contribution of RCS increased from 22% to 30% with increasing pH from 6 to 9. The degradation was initiated by HO-induced hydroxylation and Cl-induced chlorine substitution, and sustained through decarboxylation, demethylation, chlorination and ring cleavage to form more stable products. Significant amounts of chlorinated intermediates/byproducts were formed from the UV/chlorine AOP, and four chlorinated products were newly identified. The yield of total organic chlorine (TOCl) was 31.6 μM after 90% degradation of 50 μM IBP under the experimental conditions. The known disinfection by-products (DBPs) comprised 17.4% of the TOCl. The effects of water matrix in filtered drinking water on the degradation were not significant, demonstrating the practicality of the UV/chlorine AOP for the control of some refractory PPCPs. However, the toxicity of the chlorinated products should be further assessed.

  17. Degradation of cytokinins by maize cytokinin dehydrogenase is mediated by free radicals generated by enzymatic oxidation of natural benzoxazinones

    OpenAIRE

    Frébortová, J. (Jitka); Novák, O.; Frébort, I. (Ivo); Jorda, R. (Radek)

    2010-01-01

    Hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-one (DIMBOA) was isolated from maize phloem sap as a compound enhancing the degradation of isopentenyl adenine by maize cytokinin dehydrogenase (CKX), after oxidative conversion by either laccase or peroxidase. Laccase and peroxidase catalyze oxidative cleavage of DIMBOA to 4-nitrosoresorcinol-1-monomethyl ether (coniferron), which serves as a weak electron acceptor of CKX. The oxidation of DIMBOA and coniferron generates transitional fre...

  18. Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme.

    Science.gov (United States)

    Yui, Daishi; Nishida, Yoichiro; Nishina, Tomoko; Mogushi, Kaoru; Tajiri, Mio; Ishibashi, Satoru; Ajioka, Itsuki; Ishikawa, Kinya; Mizusawa, Hidehiro; Murayama, Shigeo; Yokota, Takanori

    2015-01-01

    Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD) model mice showed decreased insulin-degrading enzyme (IDE) levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa-/-) mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa-/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3); Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa-/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD.

  19. Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme.

    Directory of Open Access Journals (Sweden)

    Daishi Yui

    Full Text Available Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD model mice showed decreased insulin-degrading enzyme (IDE levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa-/- mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa-/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3; Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa-/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD.

  20. Anodic oxidation of salicylic acid on BDD electrode: Variable effects and mechanisms of degradation

    International Nuclear Information System (INIS)

    Highlights: ► Oxidation with BDD is a powerful electrochemical method able to mineralize. ► SA is oxidized to aromatic compounds then CO2 and H2O. ► Polymeric intermediate products were formed. - Abstract: The degradation of 100 mL of solution with salicylic acid (SA) in the pH range 3.0–10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 3 cm2 area, by applying a current of 100, 300 and 450 mA at 25 °C. Completed mineralization is always achieved due to the great concentration of hydroxyl radical (·OH) generated at the BDD surface. The mineralization rate increases with increasing applied current, but decreases when drug concentration rises from 200 mg L−1. Nevertheless, the pH effect was not significant. During oxidation it was observed that catechol, 2,5-dihydroxylated benzoic acid, 2,3-dihydroxylated benzoic acid and hydroquinone were formed as aromatic intermediates. In addition, ion-exclusion chromatography allowed the detection of fumaric, maleic, oxalic and formic as the ultimate carboxylic acid.

  1. Anodic oxidation of salicylic acid on BDD electrode: Variable effects and mechanisms of degradation

    Energy Technology Data Exchange (ETDEWEB)

    Rabaaoui, Nejmeddine, E-mail: chimie_tunisie@yahoo.fr [Faculte des Sciences de Sfax, Departement de Chimie, 3038 Sfax (Tunisia); Allagui, Mohamed Salah [Faculte des Sciences de Gafsa, Campus Universitaire Sidi Ahmed Zarrouk, 2112 Gafsa (Tunisia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Oxidation with BDD is a powerful electrochemical method able to mineralize. Black-Right-Pointing-Pointer SA is oxidized to aromatic compounds then CO{sub 2} and H{sub 2}O. Black-Right-Pointing-Pointer Polymeric intermediate products were formed. - Abstract: The degradation of 100 mL of solution with salicylic acid (SA) in the pH range 3.0-10.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 3 cm{sup 2} area, by applying a current of 100, 300 and 450 mA at 25 Degree-Sign C. Completed mineralization is always achieved due to the great concentration of hydroxyl radical ({center_dot}OH) generated at the BDD surface. The mineralization rate increases with increasing applied current, but decreases when drug concentration rises from 200 mg L{sup -1}. Nevertheless, the pH effect was not significant. During oxidation it was observed that catechol, 2,5-dihydroxylated benzoic acid, 2,3-dihydroxylated benzoic acid and hydroquinone were formed as aromatic intermediates. In addition, ion-exclusion chromatography allowed the detection of fumaric, maleic, oxalic and formic as the ultimate carboxylic acid.

  2. Methylmercury oxidative degradation potentials in contaminated and pristine sediments of the Carson River, Nevada

    Science.gov (United States)

    Oremland, R.S.; Miller, L.G.; Dowdle, P.; Connell, T.; Barkay, T.

    1995-01-01

    Sediments from mercury-contaminated and uncontaminated reaches of the Carson River, Nevada, were assayed for sulfate reduction, methanogenesis, denitrification, and monomethylmercury (MeHg) degradation. Demethylation of [14C]MeHg was detected at all sites as indicated by the formation of 14CO2 and 14CH4. Oxidative demethylation was indicated by the formation of 14CO2 and was present at significant levels in all samples. Oxidized/reduced demethylation product ratios (i.e., 14CO2/14CH4 ratios) generally ranged from 4.0 in surface layers to as low as 0.5 at depth. Production of 14CO2 was most pronounced at sediment surfaces which were zones of active denitrification and sulfate reduction but was also significant within zones of methanogenesis. In a core taken from an uncontaminated site having a high proportion of oxidized, coarse-grain sediments, sulfate reduction and methanogenic activity levels were very low and 14CO2 accounted for 98% of the product formed from [14C]MeHg. There was no apparent relationship between the degree of mercury contamination of the sediments and the occurrence of oxidative demethylation. However, sediments from Fort Churchill, the most contaminated site, were most active in terms of demethylation potentials. Inhibition of sulfate reduction with molybdate resulted in significantly depressed oxidized/reduced demethylation product ratios, but overall demethylation rates of inhibited and uninhibited samples were comparable. Addition of sulfate to sediment slurries stimulated production of 14CO2 from [14C]MeHg, while 2-bromoethanesulfonic acid blocked production of 14CH4. These results reveal the importance of sulfate-reducing and methanogenic bacteria in oxidative demethylation of MeHg in anoxic environments.

  3. An evaluation of a pilot-scale nonthermal plasma advanced oxidation process for trace organic compound degradation.

    Science.gov (United States)

    Gerrity, Daniel; Stanford, Benjamin D; Trenholm, Rebecca A; Snyder, Shane A

    2010-01-01

    This study evaluated a pilot-scale nonthermal plasma (NTP) advanced oxidation process (AOP) for the degradation of trace organic compounds such as pharmaceuticals and potential endocrine disrupting compounds (EDCs). The degradation of seven indicator compounds was monitored in tertiary-treated wastewater and spiked surface water to evaluate the effects of differing water qualities on process efficiency. The tests were also conducted in batch and single-pass modes to examine contaminant degradation rates and the remediation capabilities of the technology, respectively. Values for electrical energy per order (EEO) of magnitude degradation ranged from meprobamate) in wastewater. Changes in the bulk organic matter based on UV(254) absorbance and excitation-emission matrices (EEM) were also monitored and correlated to contaminant degradation. These results indicate that NTP may be a viable alternative to more common AOPs due to its comparable energy requirements for contaminant degradation and its ability to operate without any additional feed chemicals. PMID:19822343

  4. DI-(2-ETHYLHEXYL PHTHALATE OXIDATIVE DEGRADATION BY FENTON PROCESS IN SYNTHETIC AND REAL PETROCHEMICAL WASTEWATER

    Directory of Open Access Journals (Sweden)

    R. Esmaeli

    2011-09-01

    Full Text Available Di-(2-Ethylhexyl phthalate (DEHP belongs to the class of phthalate esters and is used as an additive in many products including plastics, paints and inks or as a solvent in industrial formulations. The degradation of DEHP in aqueous solution using oxidative Fenton reaction (H2O2/Fe2+ was carried out in this study. It was found that H2O2 concentration, Fe2+ concentration, and pH were the three main factors that could significantly influence the degradation rates of DEHP. The highest degradation percentage (85.6 % of DEHP was observed within 60 min at pH 3 in H2O2/Fe2+ system. The results of our study suggested that the concentration with 90 mg/L H2O2, 5 mg/L Fe2+, and 20 mg/L DEHP in the solution at pH 3 were the optimal conditions. The optimized reaction parameters were preceded for treatment of real wastewater obtained from a petrochemical plant.

  5. Degradation and inactivation of adenovirus in water by photo-electro-oxidation.

    Science.gov (United States)

    Monteiro, G S; Staggemeier, R; Klauck, C R; Bernardes, A M; Rodrigues, M A S; Spilki, F R

    2015-12-01

    The present study analyzed the efficiency of the photo-electro-oxidation process as a method for degradation and inactivation of adenovirus in water. The experimental design employed a solution prepared from sterile water containing 5.107 genomic copies/L (gc/L) of a standard strain of human adenovirus type 5 (HAdV-5) divided into two equal parts, one to serve as control and one treated by photo-electro-oxidation (PEO) for 3 hours and with a 5A current. Samples collected throughout the exposure process were analyzed by real-time polymerase chain reaction (qPCR) for viral genome identification and quantitation. Prior to gene extraction, a parallel DNAse treatment step was carried out to assess the integrity of viral particles. Integrated cell culture (ICC) analyses assessed the viability of infection in a cell culture. The tested process proved effective for viral degradation, with a 7 log10 reduction in viral load after 60 minutes of treatment. The DNAse-treated samples exhibited complete reduction of viral load after a 75 minute exposure to the process, and ICC analyses showed completely non-viable viral particles at 30 minutes of treatment. PMID:26628240

  6. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, S.S. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Shinde, P.S. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Sapkal, R.T. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Oh, Y.W. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Haranath, D. [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110 012 (India); Bhosale, C.H. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Rajpure, K.Y., E-mail: rajpure@yahoo.com [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Influence of substrate temperature onto the physico-chemical properties. Black-Right-Pointing-Pointer Photochemical, structural, luminescent, optoelectrical and thermal properties. Black-Right-Pointing-Pointer The kinetics of oxalic acid degradation with reaction mechanism. Black-Right-Pointing-Pointer Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV-Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (I{sub sc} = 0.357 mA) and open circuit voltage (V{sub oc} = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14-3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  7. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    International Nuclear Information System (INIS)

    Highlights: ► Influence of substrate temperature onto the physico-chemical properties. ► Photochemical, structural, luminescent, optoelectrical and thermal properties. ► The kinetics of oxalic acid degradation with reaction mechanism. ► Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV–Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (Isc = 0.357 mA) and open circuit voltage (Voc = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14–3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  8. Degradation of estrone in water and wastewater by various advanced oxidation processes.

    Science.gov (United States)

    Sarkar, Shubhajit; Ali, Sura; Rehmann, Lars; Nakhla, George; Ray, Madhumita B

    2014-08-15

    A comprehensive study was conducted to determine the relative efficacy of various advanced oxidation processes such as O3, H2O2, UV, and combinations of UV/O3, UV/H2O2 for the removal of estrone (E1) from pure water and secondary effluent. In addition to the parent compound (E1) removal, performance of the advanced oxidation processes was characterized using removal of total organic carbon (TOC), and estrogenicity of the effluent. Although E1 removal was high for all the AOPs, intermediates formed were more difficult to degrade leading to slow TOC removal. Energy calculations and cost analysis indicated that, although UV processes have low electricity cost, ozonation is the least cost option ($ 0.34/1000 gallons) when both capital and operating costs were taken into account. Ozonation also is superior to the other tested AOPs due to higher removal of TOC and estrogenicity. The rate of E1 removal decreased linearly with the background TOC in water, however, E1 degradation in the secondary effluent from a local wastewater treatment plant was not affected significantly due to the low COD values in the effluent.

  9. Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review.

    Science.gov (United States)

    Tisa, Farhana; Abdul Raman, Abdul Aziz; Wan Daud, Wan Mohd Ashri

    2014-12-15

    Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs. PMID:25190594

  10. Oxidative stress induces caveolin 1 degradation and impairs caveolae functions in skeletal muscle cells.

    Directory of Open Access Journals (Sweden)

    Alexis Mougeolle

    Full Text Available Increased level of oxidative stress, a major actor of cellular aging, impairs the regenerative capacity of skeletal muscle and leads to the reduction in the number and size of muscle fibers causing sarcopenia. Caveolin 1 is the major component of caveolae, small membrane invaginations involved in signaling and endocytic trafficking. Their role has recently expanded to mechanosensing and to the regulation of oxidative stress-induced pathways. Here, we increased the amount of reactive oxidative species in myoblasts by addition of hydrogen peroxide (H2O2 at non-toxic concentrations. The expression level of caveolin 1 was significantly decreased as early as 10 min after 500 μM H2O2 treatment. This reduction was not observed in the presence of a proteasome inhibitor, suggesting that caveolin 1 was rapidly degraded by the proteasome. In spite of caveolin 1 decrease, caveolae were still able to assemble at the plasma membrane. Their functions however were significantly perturbed by oxidative stress. Endocytosis of a ceramide analog monitored by flow cytometry was significantly diminished after H2O2 treatment, indicating that oxidative stress impaired its selective internalization via caveolae. The contribution of caveolae to the plasma membrane reservoir has been monitored after osmotic cell swelling. H2O2 treatment increased membrane fragility revealing that treated cells were more sensitive to an acute mechanical stress. Altogether, our results indicate that H2O2 decreased caveolin 1 expression and impaired caveolae functions. These data give new insights on age-related deficiencies in skeletal muscle.

  11. A distributed real-time model of degradation in a solid oxide fuel cell, part I: Model characterization

    Science.gov (United States)

    Zaccaria, V.; Tucker, D.; Traverso, A.

    2016-04-01

    Despite the high efficiency and flexibility of fuel cells, which make them an attractive technology for the future energy generation, their economic competitiveness is still penalized by their short lifetime, due to multiple degradation phenomena. As a matter of fact, electrochemical performance of solid oxide fuel cells (SOFCs) is reduced because of different degradation mechanisms, which depend on operating conditions, fuel and air contaminants, impurities in materials, and others. In this work, a real-time, one dimensional (1D) model of a SOFC is used to simulate the effects of voltage degradation in the cell. Different mechanisms are summarized in a simple empirical expression that relates degradation rate to cell operating parameters (current density, fuel utilization and temperature), on a localized basis. Profile distributions of different variables during cell degradation are analyzed. In particular, the effect of degradation on current density, temperature, and total resistance of the cell are investigated. An analysis of localized degradation effects shows how different parts of the cell degrade at a different time rate, and how the various profiles are redistributed along the cell as consequence of different degradation rates.

  12. Bioremediation of phenanthrene, chrysene and benzo[a]pyrene by fungi screened from nature

    Directory of Open Access Journals (Sweden)

    Tony Hadibarata

    2009-09-01

    Full Text Available Laccase of Polyporus sp. S133 was able to oxidize most of the 3 different rings amount polycyclic aromatic hydrocarbons (PAHs tested. Phenanthrene was removed by 89% followed by chrysene and benzo[a]pyrene which were oxidized by 66 and 55%, respectively. Addition of 1-hydroxybenzotriazole (HBT to the reaction mixture increased oxidation of PAHs, especially phenanthrene was almost completely removed from the reaction mixture. Oxidation of chrysene and benzo[a]anthracene increased 12 and 10% with the mediator to 78 and 65% in the presence of HBT. PAH-quinones as oxidation products were formed from all PAH to different extents. A part of PAH was polymerized in the laccase/mediator system to products of weight-average molecular weight (MW. The correlation of the ionization potentials of PAH with the oxidation of these compounds is limited to the alternating PAH.

  13. Degradation of Phenol with Fenton-like Treatment by Using Heterogeneous Catalyst (Modified Iron Oxide) and Hydrogen Peroxide

    International Nuclear Information System (INIS)

    Goethite, hematite, magnetite and synthesized iron oxide are used as catalysts for Fenton-type oxidation of phenol. The synthesized iron oxides were characterized by X-ray diffraction (XRD), BET, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR). The catalytic activity of these materials is classified according to the observed rate of phenol oxidation. The effectiveness of the catalysts followed the sequence: ferrous ion > synthesized iron oxide >> magnetite hematite > goethite. According to these results, the most effective iron oxide catalyst had the structure similar to natural hematite. The surface oxidation state of the catalyst was between magnetite and hematite (+2.5 ∼ +3.0). Phenol degraded completely in 40 min at neutral pH (pH = 7). Soluble ferric and ferrous ions were not detected in the filtrate from Fenton reaction solution by AAS. The formation of hydroxyl radicals was confirmed by EPR

  14. Electrochemical detection of benzo(a)pyrene and related DNA damage using DNA/hemin/nafion–graphene biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Yongnian, E-mail: ynni@ncu.edu.cn [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Wang, Pingping; Song, Haiyan [Department of Chemistry, Nanchang University, Nanchang 330031 (China); Lin, Xiaoyun [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Kokot, Serge, E-mail: s.kokot@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane 4001 (Australia)

    2014-04-01

    Graphical abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed to quantitatively study the DNA damage induced by the metabolite of benzo(a)pyrene in the presence of H{sub 2}O{sub 2}. - Highlights: • Construction of a novel DNA/hemin/nafion-graphene/GCE biosensor. • DNA damage induced by the benzo(a)pyrene metabolite was detected. • DPV analysis of benzo(a)pyrene provided a quantitative estimate of DNA damage. • Hemin/H{sub 2}O{sub 2} system could mimic the cytochrome P450 to metabolize benzo(a)pyrene. - Abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed for the analysis of the benzo(a)pyrene PAH, which can produce DNA damage induced by a benzo(a)pyrene (BaP) enzyme-catalytic product. This biosensor was assembled layer-by-layer, and was characterized with the use of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy. Ultimately, it was demonstrated that the hemin/nafion–graphene/GCE was a viable platform for the immobilization of DNA. This DNA biosensor was treated separately in benzo(a)pyrene, hydrogen peroxide (H{sub 2}O{sub 2}) and in their mixture, respectively, and differential pulse voltammetry (DPV) analysis showed that an oxidation peak was apparent after the electrode was immersed in H{sub 2}O{sub 2}. Such experiments indicated that in the presence of H{sub 2}O{sub 2}, hemin could mimic cytochrome P450 to metabolize benzo(a)pyrene, and a voltammogram of its metabolite was recorded. The DNA damage induced by this metabolite was also detected by electrochemical impedance and ultraviolet spectroscopy. Finally, a novel, indirect DPV analytical method for BaP in aqueous solution was developed based on the linear metabolite versus BaP concentration plot; this method provided a new, indirect, quantitative estimate of DNA damage.

  15. Solar photocatalytic degradation of resorcinol a model endocrine disrupter in water using zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Pardeshi, S.K. [Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007 (India)], E-mail: skpar@chem.unipune.ernet.in; Patil, A.B. [Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007 (India)

    2009-04-15

    Photocatalytic degradation (PCD) of resorcinol a potent endocrine disrupting chemical in aqueous medium was investigated by ZnO under sunlight irradiation in a batch photoreactor. The influence of various parameters such as photocatalyst amount, initial concentration of resorcinol and pH was examined for maximum PCD of resorcinol. A considerable influence of pH upon the chemical oxygen demand (COD) disappearance was observed. In general, neutral or basic pH is favorable for COD removal of resorcinol. PCD intermediates were identified using FTIR and GC/MS. Two of the initial oxidation intermediates detected were 1,2,4-trihydroxy-benzene and 1,2,3-trihydroxy-benzene. FTIR studies revealed 1,2,4-trihydroxy-benzene as the major PCD intermediate. A working photodegradation mechanism is also suggested for PCD of resorcinol. This work envisages the great potential that sunlight mediated photocatalysis has in the removal of resorcinol from waste water.

  16. Degradation of the fluoroquinolone enrofloxacin by electrochemical advanced oxidation processes based on hydrogen peroxide electrogeneration

    Energy Technology Data Exchange (ETDEWEB)

    Guinea, Elena; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Cabot, Pere-Lluis; Arias, Conchita; Centellas, Francesc [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.ed [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-02-15

    Solutions of the veterinary fluoroquinolone antibiotic enrofloxacin in 0.05 M Na{sub 2}SO{sub 4} of pH 3.0 have been comparatively degraded by electrochemical advanced oxidation processes such as anodic oxidation with electrogenerated H{sub 2}O{sub 2} (AO-H{sub 2}O{sub 2}), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF) at constant current density. The study has been performed using an undivided stirred tank reactor of 100 ml and a batch recirculation flow plant of 2.5 l with an undivided filter-press cell coupled to a solar photoreactor, both equipped with a Pt or boron-doped diamond (BDD) anode and a carbon-polytetrafluoroethylene gas diffusion cathode to generate H{sub 2}O{sub 2} from O{sub 2} reduction. In EF, PEF and SPEF, hydroxyl radical (centre dotOH) is formed from Fenton's reaction between added catalytic Fe{sup 2+} and generated H{sub 2}O{sub 2}. Almost total decontamination of enrofloxacin solutions is achieved in the stirred tank reactor by SPEF with BDD. The use of the batch recirculation flow plant showed that this process is the most efficient and can be viable for industrial application, becoming more economic and yielding higher mineralization degree with raising antibiotic content. This is feasible because organics are quickly oxidized with centre dotOH formed from Fenton's reaction and at BDD from water oxidation, combined with the fast photolysis of complexes of Fe(III) with generated carboxylic acids under solar irradiation. The lower intensity of UVA irradiation used in PEF with BDD causes a slower degradation. EF with BDD is less efficient since centre dotOH cannot destroy the most persistent Fe(III)-oxalate and Fe(III)-oxamate complexes. AO-H{sub 2}O{sub 2} with BDD yields the poorest mineralization because pollutants are only removed with centre dotOH generated at BDD. All procedures are less potent using Pt as anode due to the lower production of centre dotOH at its surface. Enrofloxacin

  17. Degradation of the fluoroquinolone enrofloxacin by electrochemical advanced oxidation processes based on hydrogen peroxide electrogeneration

    International Nuclear Information System (INIS)

    Solutions of the veterinary fluoroquinolone antibiotic enrofloxacin in 0.05 M Na2SO4 of pH 3.0 have been comparatively degraded by electrochemical advanced oxidation processes such as anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF) at constant current density. The study has been performed using an undivided stirred tank reactor of 100 ml and a batch recirculation flow plant of 2.5 l with an undivided filter-press cell coupled to a solar photoreactor, both equipped with a Pt or boron-doped diamond (BDD) anode and a carbon-polytetrafluoroethylene gas diffusion cathode to generate H2O2 from O2 reduction. In EF, PEF and SPEF, hydroxyl radical (·OH) is formed from Fenton's reaction between added catalytic Fe2+ and generated H2O2. Almost total decontamination of enrofloxacin solutions is achieved in the stirred tank reactor by SPEF with BDD. The use of the batch recirculation flow plant showed that this process is the most efficient and can be viable for industrial application, becoming more economic and yielding higher mineralization degree with raising antibiotic content. This is feasible because organics are quickly oxidized with ·OH formed from Fenton's reaction and at BDD from water oxidation, combined with the fast photolysis of complexes of Fe(III) with generated carboxylic acids under solar irradiation. The lower intensity of UVA irradiation used in PEF with BDD causes a slower degradation. EF with BDD is less efficient since ·OH cannot destroy the most persistent Fe(III)-oxalate and Fe(III)-oxamate complexes. AO-H2O2 with BDD yields the poorest mineralization because pollutants are only removed with ·OH generated at BDD. All procedures are less potent using Pt as anode due to the lower production of ·OH at its surface. Enrofloxacin decay always follows a pseudo first-order reaction. Its primary aromatic by-products and short intermediates including polyols, ketones

  18. Peroxidase-induced degradation of single-walled carbon nanotubes: hypochlorite is a major oxidant capable of in vivo degradation of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vlasova, I I; Vakhrusheva, T V; Sokolov, A V; Kostevich, V A [Research Institute for Physico-Chemical Medicine, FMBA, M. Pirogovskaya Str. 1a, Moscow (Russian Federation); Ragimov, A A, E-mail: irina.vlasova@yahoo.com [National Research Centre of Surgery, RAMS, Abrikosovskiy per. 2, Moscow (Russian Federation)

    2011-04-01

    Due to their extraordinary properties, single-walled carbon nanotubes (SWNTs) have a tremendous potential for medical applications such as clinical diagnostics, targeted drug (or gene) delivery and cancer therapy. Hence, effects of SWNTs on living systems as well as mechanisms for biodegradation of SWTNs are of great importance and must be studied before starting to explore SWNTs for medical use. This study was undertaken to compare the potential of different peroxidases in degrading carboxylated SWNT (c-SWNT) and to elucidate the role of peroxidase-generated reactive products in this process. A detailed study showed that neither reactive intermediate products nor free radicals generated via peroxidase cycle can considerably oxidize c-SWNT. Biodegradation of c-SWNT in model system can be induced by free radicals generated as a result of heme degradation. The latter explains why hemoglobin, which is a pseudo-peroxidase possessing low peroxidase activity, is able to oxidize carbon nanotubes with a higher efficiency than horseradish peroxidase. However, c-SWNT in the presence of blood plasma (15 vol %) demonstrated no degradation even at high concentrations of hemoglobin and H{sub 2}O{sub 2}. The comparison of the ability of various peroxidases to degrade SWNTs in vitro revealed that MPO, due to its ability to produce hypochlorite, and lactoperoxidase, due to its ability to produce hypobromite, are extremely efficient in degrading carbon nanotubes. Since neutrophils are a main source of human MPO, we tested the effect of SWNTs on these cells. SWNTs were unable to stimulate neutrophils. On the other hand, they dose-dependently enhanced opsonized zymosan-induced cell stimulation as detected by measuring the amount of hypochlorite produced. This finding may be relevant to the in vivo situation, for example, at inflammatory sites. In order to imitate conditions characteristic of phagosomes and inflammatory sites, we titrated the suspension of c-SWNT in the presence of

  19. New photocatalyst based on graphene oxide/chitin for degradation of dyes under sunlight.

    Science.gov (United States)

    Wang, Yuntao; Pei, Yaqiong; Xiong, Wenfei; Liu, Tingguo; Li, Jing; Liu, Shilin; Li, Bin

    2015-11-01

    Sunlight photocatalyst was fabricated by in situ synthesis of Cu2O in the regenerated chitin (RC)/graphene oxide (GO) composite film, where the porous chitin film was used as the microreactor for the formation of nano Cu2O. Nano Cu2O was immobilized and evenly distributed in the matrix and Cu2O tended to grow on the GO sheets. Cu2O inside the matrix excite and generate free photoelectrons and electron holes, which was responsible for the degradation of dyes, while GO transferred the yielded photoelectrons to prevent the generation of local high potential zone and induce the chain degradation at more points. So it was found that the porous chitin film could load Cu2O and graphene at the same time, controlling the size of Cu2O and leading to easy recycle and reuse of the photocatalyst. Moreover, the introduction of GO has dramatically improved the photocatalytic activity of Cu2O in the Cu2O/GO/RC film, showing great potential application in wastewater treatment utilizing solar energy. PMID:26299711

  20. Comparative study of photocatalytic oxidation on the degradation of formaldehyde and fuzzy mathematics evaluation of filters

    Science.gov (United States)

    Yu, Huili; Zhang, Jieting

    2012-04-01

    In this study, formaldehyde, one of the major volatile organic compounds, is chosen as the target pollutant. The polytetrafluoroethylene (PTFE) filter, a low cost and commonly used material in industry, is employed as the substrate for nano TiO2 photocatalyst coating at room temperature, which has been scarcely used compared to ceramics or glass beads. Furthermore, a specific experimental set-up that is similar to actual air purification system is developed for the testing. The degradation mechanisms of photolysis reaction, adsorption and photocatalytic oxidation reaction on volatile organic compounds are present respectively. The influences of three aspects mentioned above are compared by a serial of experimental data. The high efficiency of volatile organic compounds on the degradation of formaldehyde is assured. Furthermore, the purification characteristics of three kinds of activated carbon filters and PTFE filter with nano TiO2 are evaluated with the method of fuzzy mathematics. In the end, the result shows that the filter with nano TiO2 has the optimal comprehensive performances.

  1. Facile synthesis of zinc oxide nanoparticles decorated graphene oxide composite via simple solvothermal route and their photocatalytic activity on methylene blue degradation.

    Science.gov (United States)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Perumal, Suguna; Karthikeyan, Dhanapalan; Lee, Yong Rok

    2016-09-01

    Zinc oxide nanoparticles decorated graphene oxide (ZnO@GO) composite was synthesized by simple solvothermal method where zinc oxide (ZnO) nanoparticles and graphene oxide (GO) were synthesized via simple thermal oxidation and Hummers method, respectively. The obtained materials were thoroughly characterized by various physico-chemical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Raman spectrum shows the intensity of D to G value was close to one which confirms the obtained GO and ZnO@GO composite possesses moderate graphitization. TEM images shows the ZnO nanoparticles mean size of 15±5nm were dispersed over the wrinkled graphene layers. The photocatalytic performance of ZnO@GO composite on degradation of methylene blue (MB) is investigated and the results show that the GO plays an important role in the enhancement of photocatalytic performance. The synthesized ZnO@GO composite achieves a maximum degradation efficiency of 98.5% in a neutral solution under UV-light irradiation for 15min as compared with pure ZnO (degradation efficiency is 49% after 60min of irradiation) due to the increased light absorption, the reduced charge recombination with the introduction of GO. Moreover, the resulting ZnO@GO composite possesses excellent degradation efficiency as compared to ZnO nanoparticles alone on MB.

  2. Tailoring oxides of copper-Cu2O and CuO nanoparticles and evaluation of organic dyes degradation

    Science.gov (United States)

    Raghav, Ragini; Aggarwal, Priyanka; Srivastava, Sudha

    2016-04-01

    We report a simple one-pot colloidal synthesis strategy tailoring cuprous or cupric nano-oxides in pure state. NaOH provided alkaline conditions (pH 12.5 -13) for nano-oxides formation, while its concentration regulated the oxidation state of the nano-oxides. The morphological, structural and optical properties of synthesized Cu2O and CuO nanoparticles were studied by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and UV-vis spectroscopy. Dye degradation capability of CuO and Cu2O nanoparticles was evaluated using four organic dyes - Malachite green, Methylene blue, Methyl orange and Methyl red. The results demonstrate effective degradation of all four dyes employing with almost comparable activity both Cu2O and CuO nanoparticles.

  3. Effect of communities of ammonia-oxidizing bacteria on degradation of 17-alpha-ethynylestradiol by nitrifying activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Limpiyakorn, T.; Sermwaraphan, P.; Kurisu, F.

    2009-07-01

    An endocrine disrupting compound, 17-alpha-ethynylestradiol (EE2), is a synthetic estrogen used as a key ingredient in oral contraceptives pill. this persistent organic pollutant, no biodegradable by most microorganisms, is discharged via municipal waste streams to natural receiving waters. Recently, it was found that ammonia-oxidizing bacteria (AOB) in nitrifying activated sludge (NAS) enriched with high ammonium loads can degrade EE2 via co-metabolism during ammonia oxidation. (Author)

  4. Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi 2 Se 3

    KAUST Repository

    Kong, Desheng

    2011-06-28

    Bismuth selenide (Bi2Se3) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi2Se3 is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi2Se3 gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi2Se3 by transport measurements. © 2011 American Chemical Society.

  5. Comparison of various advanced oxidation processes for the degradation of phenylurea herbicides.

    Science.gov (United States)

    Kovács, Krisztina; Farkas, János; Veréb, Gábor; Arany, Eszter; Simon, Gergő; Schrantz, Krisztina; Dombi, András; Hernádi, Klára; Alapi, Tünde

    2016-01-01

    Various types of advanced oxidation processes (AOPs), such as UV photolysis, ozonation, heterogeneous photocatalysis and their combinations were comparatively examined at the same energy input in a home-made reactor. The oxidative transformations of the phenylurea herbicides fenuron, monuron and diuron were investigated. The initial rates of transformation demonstrated that UV photolysis was highly efficient in the cases of diuron and monuron. Ozonation proved to be much more effective in the transformation of fenuron than in those of the chlorine containing monuron and diuron. In heterogeneous photocatalysis, the rate of decomposition decreased with increase of the number of chlorine atoms in the target molecule. Addition of ozone to UV-irradiated solutions and/or TiO2-containing suspensions markedly increased the initial rates of degradation. Dehalogenation of monuron and diuron showed that each of these procedures is suitable for the simultaneous removal of chlorinated pesticides and their chlorinated intermediates. Heterogeneous photocatalysis was found to be effective in the mineralization. PMID:26764571

  6. The distribution and degradation of radiolabeled superparamagnetic iron oxide nanoparticles and quantum dots in mice

    Directory of Open Access Journals (Sweden)

    Denise Bargheer

    2015-01-01

    Full Text Available 51Cr-labeled, superparamagnetic, iron oxide nanoparticles (51Cr-SPIOs and 65Zn-labeled CdSe/CdS/ZnS-quantum dots (65Zn-Qdots were prepared using an easy, on demand, exchange-labeling technique and their particokinetic parameters were studied in mice after intravenous injection. The results indicate that the application of these heterologous isotopes can be used to successfully mark the nanoparticles during initial distribution and organ uptake, although the 65Zn-label appeared not to be fully stable. As the degradation of the nanoparticles takes place, the individual transport mechanisms for the different isotopes must be carefully taken into account. Although this variation in transport paths can bring new insights with regard to the respective trace element homeostasis, it can also limit the relevance of such trace material-based approaches in nanobioscience. By monitoring 51Cr-SPIOs after oral gavage, the gastrointestinal non-absorption of intact SPIOs in a hydrophilic or lipophilic surrounding was measured in mice with such high sensitivity for the first time. After intravenous injection, polymer-coated, 65Zn-Qdots were mainly taken up by the liver and spleen, which was different from that of ionic 65ZnCl2. Following the label for 4 weeks, an indication of substantial degradation of the nanoparticles and the release of the label into the Zn pool was observed. Confocal microscopy of rat liver cryosections (prepared 2 h after intravenous injection of polymer-coated Qdots revealed a colocalization with markers for Kupffer cells and liver sinusoidal endothelial cells (LSEC, but not with hepatocytes. In J774 macrophages, fluorescent Qdots were found colocalized with lysosomal markers. After 24 h, no signs of degradation could be detected. However, after 12 weeks, no fluorescent nanoparticles could be detected in the liver cryosections, which would confirm our 65Zn data showing a substantial degradation of the polymer-coated CdSe/CdS/ZnS-Qdots in

  7. Treatment of pharmaceutical wastewater using interior micro-electrolysis/Fenton oxidation-coagulation and biological degradation.

    Science.gov (United States)

    Xu, Xiaoyi; Cheng, Yao; Zhang, Tingting; Ji, Fangying; Xu, Xuan

    2016-06-01

    The synthesis of steroid hormones produces wastewater that is difficult to manage and characterize due to its complex components and high levels of toxicity and bio-refractory compounds. In this work, interior micro-electrolysis (IME) and Fenton oxidation-coagulation (FOC) were investigated as wastewater pretreatment processes in combination with biological treatments using a hydrolysis acidification unit (HA) and two-stage biological contact oxidation (BCO) in laboratory and field experiments. In laboratory experiments with an average initial COD load of about 15,000 mg/L, pH of 4, Fe-C/water (V/V) ratio of 1:1, air/water ratio of 10, and reaction time of 180 min, IME achieved a COD removal efficiency of 31.8% and a 1.7-fold increase in the BOD5/COD (B/C) ratio of wastewater. The Fe(2+) concentration of 458.5 mg/L in the IME effluent meets the requirements of the Fenton oxidation (FO) process. FOC further reduced the COD with an efficiency of 30.1%, and the B/C ratio of the wastewater reached 0.59. Excitation-emission matrix (EEM) analysis showed that complex higher molecular weight organic compounds in the wastewater were degraded after the pretreatment process. In addition, a field experiment with a continuous flow of 96 m(3)/d was conducted for over 90 d. The combined process system operated steadily, though the Fe-C fillings should be soaked in a sulfuric acid solution (5‰) for 12 h to recover activity every two weeks. The COD and BOD5 concentrations in the final effluent were less than 90 mg/L and 15 mg/L, respectively. PMID:26953729

  8. Degradation of organochloride pesticides by molten salt oxidation at IPEN: spin-off nuclear activities

    International Nuclear Information System (INIS)

    Nuclear spin-off has at least two dimensions. It may provide benefits to the society such as enlarge knowledge base, strengthen infrastructure and benefit technology development. Besides this, to emphasize that some useful technologies elapsed from nuclear activities can affect favorably the public opinion about nuclear energy. In this paper is described a technology developed initially by the Rockwell Int. company in the USA more than thirty years ago to solve some problems of nuclear fuel cycle wastes. For different reasons the technology was not employed. In the last years the interest in the technology was renewed and IPEN has developed his version of the method applicable mainly to the safe degradation of hazardous wastes. This study was motivated by the world interest in the development of advanced processes of waste decomposition, due to the need of safer decomposition processes, particularly for the POPs - persistent organic pollutants and particularly for the organ chlorides. A tendency observed at several countries is the adoption of progressively more demanding legislation for the atmospheric emissions, resultants of the waste decomposition processes. The suitable final disposal of hazardous organic wastes such as PCBs (polychlorinated biphenyls), pesticides, herbicides and hospital residues constitutes a serious problem. In some point of their life cycles, these wastes should be destroyed, in reason of the risk that they represent for the human being, animals and plants. The process involves using a chemical reactor containing molten salts, sodium carbonate or some alkaline carbonates mixtures to decompose the organic waste. The decomposition is performed by submerged oxidation and the residue is injected below the surface of a turbulent salt bath along with the oxidizing agent. Decomposition of halogenated compounds, among which some pesticides, is particularly effective in molten salts. The process presents properties such as intrinsically safe

  9. Influence of the atmospheric species water, oxygen, nitrogen and carbon dioxide on the degradation of aluminum doped zinc oxide layers

    NARCIS (Netherlands)

    Theelen, M.; Dasgupta, S.; Vroon, Z.; Kniknie, B.; Barreau, N.; Berkum, J. van; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbon dioxide (CO2), oxygen (O2), nitrogen (N 2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical,

  10. Free radicals of benzo(a)pyrene and derivatives.

    OpenAIRE

    Sullivan, P D

    1985-01-01

    The evidence for biological involvement, the spectroscopic properties (especially EPR), and the reactions, of free radicals derived from benzo(a)pyrene and its methylated, hydroxylated, and fluorinated derivatives are reviewed.

  11. Innovative Protocols for in SITU MTBE Degradation by Using Molecular Probes-An Enhanced Chemical-Bio Oxidation Technique

    Energy Technology Data Exchange (ETDEWEB)

    Paul Fallgren

    2009-02-20

    In situ chemical oxidation (ISCO) is a common technology to cleanup petroleum hydrocarbon-contaminated soils and groundwater. Sodium percarbonate (SPC) is an oxidant which is activated by iron (Fe) to produce Fenton-like reactions. Western Research Institute, in conjunction with Regenesis and the U.S. Department of Energy, conducted a study that investigated the performance of a 'safe' oxidant, SPC, to cleanup groundwater and soils contaminated with petroleum hydrocarbons and associated contaminants (e.g., MTBE). Results from a field pilot test in Frenchglen, Oregon showed VOC concentrations in groundwater decreased substantially within 2 weeks after injecting activated SPC (RegenOx). A protocol was established for determining RegenOx TOD in soils and groundwater. Total oxidant demand tests were necessary to determine the correct dosage of RegenOx to apply in the field and sufficiently degrade the contaminants of concern. Bench studies with RegenOx showed this technology was effective in degrading diesel fuel and 1,4-dioxane. The Fe-silica activator (RegenOx Part B) was tested with another oxidant, sodium persulfate. Bench tests results showed the combination of sodium persulfate and RegenOx Part B was effective in reducing PCE, MTBE, benzene, and n-heptane concentrations in water. Overall, the results of this project indicated that most petroleum contaminants in soil and groundwater can be sufficiently degraded using the RegenOx technology.

  12. Degradation of 1-hydroxy-2,4-dinitrobenzene from aqueous solutions by electrochemical oxidation: role of anodic material.

    Science.gov (United States)

    Quiroz, Marco A; Sánchez-Salas, José L; Reyna, Silvia; Bandala, Erick R; Peralta-Hernández, Juan M; Martínez-Huitle, Carlos A

    2014-03-15

    Electrochemical oxidation (ECOx) of 1-hydroxy-2,4-dinitrobenzene (or 2,4-dinitrophenol: 2,4-DNP) in aqueous solutions by electrolysis under galvanostatic control was studied at Pb/PbO2, Ti/SnO2, Ti/IrxRuySnO2 and Si/BDD anodes as a function of current density applied. Oxidative degradation of 2,4-DNP has clearly shown that electrode material and the current density applied were important parameters to optimize the oxidation process. It was observed that 2,4-DNP was oxidized at few substrates to CO2 with different results, obtaining good removal efficiencies at Pb/PbO2, Ti/SnO2 and Si/BDD anodes. Trends in degradation way depend on the production of hydroxyl radicals (OH) on these anodic materials, as confirmed in this study. Furthermore, HPLC results suggested that two kinds of intermediates were generated, polyhydroxylated intermediates and carboxylic acids. The formation of these polyhydroxylated intermediates seems to be associated with the denitration step and substitution by OH radicals on aromatic rings, this being the first proposed step in the reaction mechanism. These compounds were successively oxidized, followed by the opening of aromatic rings and the formation of a series of carboxylic acids which were at the end oxidized into CO2 and H2O. On the basis of these information, a reaction scheme was proposed for each type of anode used for 2,4-D oxidation.

  13. Evidence of CFC degradation in groundwater under pyrite-oxidizing conditions

    Science.gov (United States)

    Sebol, L.A.; Robertson, W.D.; Busenberg, E.; Plummer, L.N.; Ryan, M.C.; Schiff, S.L.

    2007-01-01

    A detailed local-scale monitoring network was used to assess CFC distribution in an unconfined sand aquifer in southwestern Ontario where the zone of 1-5-year-old groundwater was known with certainty because of prior use of a bromide tracer. Groundwater ???5 years old was confined to an aerobic zone at ???5 m depth and had CFC concentrations consistent with modern atmospheric mixing ratios at recharge temperatures of 7-11 ??C, as was observed in the 3-m thick vadose zone at the site. At depths below 6 m, the groundwater became progressively more reducing, however, with a denitrifying horizon at 6-7 m depth, and a Mn and Fe reducing zone below 7 m depth. In the anaerobic zone, 3H/3He ratios indicated that groundwater-age continued to increase uniformly with depth, to a maximum value of 27 years at 13 m depth. CFC concentrations, however, decreased abruptly within the denitrifying zone, leading to substantial age overestimation compared to the 3H/3He ages. Noble gas data indicated that the apparent CFC mass loss was not likely the result of gas stripping from possible bubble formation; thus, CFC degradation was indicated in the anoxic zone. The field data are consistent with first-order degradation rates of 0.3 yr-1 for CFC-12, 0.7 yr-1 for CFC-11, and 1.6 yr-1 for CFC-113. CFC attenuation at this site coincides with a zone where reduced S (pyrite) is actively oxidized by NO3 and dissolved oxygen (DO). Similar behavior has been observed at other sites [Tesoriero, A.J., Liebscher, H., Cox, S.E., 2000. Mechanism and rate of denitrification in an agricultural watershed: electron and mass balance along groundwater flow path. Water Resour. Res. 36 (6), 1545-1559; Hinsby, K., Hojberg, A.L., Engesgaard, P., Jensen, K.H., Larsen, F., Plummer, L.N., Busenberg, E., Accepted for publication. Transport and degradation of chlorofluorocarbons (CFCs) in a pyritic aquifer, Rabis Creek, Denmark. Water Resour. Res.], further demonstrating that the use of CFCs for age-dating anaerobic

  14. Green synthesis of colloidal copper oxide nanoparticles using Carica papaya and its application in photocatalytic dye degradation

    Science.gov (United States)

    Sankar, Renu; Manikandan, Perumal; Malarvizhi, Viswanathan; Fathima, Tajudeennasrin; Shivashangari, Kanchi Subramanian; Ravikumar, Vilwanathan

    2014-03-01

    Copper oxide (CuO) nanoparticles were synthesized by treating 5 mM cupric sulphate with Carica papaya leaves extract. The kinetics of the reaction was studied using UV-visible spectrophotometry. An intense surface Plasmon resonance between 250-300 nm in the UV-vis spectrum clearly reveals the formation of copper oxide nanoparticles. The results of scanning electron microscopy (SEM) and dynamic light scattering (DLS) exhibited that the green synthesized copper oxide nanoparticles are rod in shape and having a mean particle size of 140 nm, further negative zeta potential disclose its stability at -28.9 mV. The Fourier-transform infrared (FTIR) spectroscopy results examined the occurrence of bioactive functional groups required for the reduction of copper ions. X-ray diffraction (XRD) spectra confirmed the copper oxide nanoparticles crystalline nature. Furthermore, colloidal copper oxide nanoparticles effectively degrade the Coomassie brilliant blue R-250 dye beneath the sunlight.

  15. Quantitative assessment on the contribution of direct photolysis and radical oxidation in photochemical degradation of 4-chlorophenol and oxytetracycline.

    Science.gov (United States)

    Liu, Yiqing; He, Xuexiang; Fu, Yongsheng; Dionysiou, Dionysios D

    2016-07-01

    In UV-254 nm/H2O2 advanced oxidation process (AOP), the potential degradation pathways for organic pollutants include (1) hydrolysis, (2) direct H2O2 oxidation, (3) UV direct photolysis, and (4) hydroxyl radical (HO(•)) reaction. In this study, the contribution of these pathways was quantitatively assessed in the photochemical destruction of 4-chlorophenol (4-CP), demonstrating pathways (3) and (4) to be predominantly responsible for the removal of 4-CP by UV/H2O2 in 50 mM phosphate buffer solution. Increasing reaction pH could significantly enhance the contribution of direct photolysis in UV/H2O2 process. The contribution of HO(•) oxidation was improved with increasing initial H2O2 concentration probably due to the increased formation of HO(•). Presence of sodium carbonate (Na2CO3) as in UV/H2O2/Na2CO3 system promoted the degradation of 4-CP, with carbonate radical (CO3 (•-)) reaction and direct photolysis identified to be the main contributing pathways. The trends in the contribution of each factor were further evaluated and validated on the degradation of the antibiotic compound oxytetracycline (OTC). This study provides valuable information on the relative importance of different reaction pathways on the photochemical degradation of organic contaminants such as 4-CP and OTC in the presence and absence of a CO3 (•-) precursor. PMID:27055892

  16. The anthocyanidin delphinidin mobilizes endogenous copper ions from human lymphocytes leading to oxidative degradation of cellular DNA

    International Nuclear Information System (INIS)

    Epidemiological and experimental evidence exists to suggest that pomegranate and its juice possess chemopreventive and anticancer properties. The anthocyanidin delphinidin is a major polyphenol present in pomegranates and has been shown to be responsible for these effects. Plant polyphenols are recognized as naturally occurring antioxidants but also catalyze oxidative DNA degradation of cellular DNA either alone or in the presence of transition metal ions such as copper. In this paper we show that similar to various other classes of polyphenols, delphinidin is also capable of causing oxidative degradation of cellular DNA. Lymphocytes were exposed to various concentrations of delphinidin (10, 20, 50 μM) for 1 h and the DNA breakage was assessed using single cell alkaline gel electrophoresis (Comet assay). Inhibition of DNA breakage by several scavengers of reactive oxygen species (ROS) indicated that it is caused by the formation of ROS. Incubation of lymphocytes with neocuproine (a cell membrane permeable Cu(I) chelator) inhibited DNA degradation in intact lymphocytes in a dose dependent manner. Bathocuproine, which is unable to permeate through the cell membrane, did not cause such inhibition. We have further shown that delphinidin is able to degrade DNA in cell nuclei and that such DNA degradation is also inhibited by neocuproine suggesting that nuclear copper is mobilized in this reaction. These results indicate that the generation of ROS possibly occurs through mobilization of endogenous copper ions. The results are in support of our hypothesis that the prooxidant activity of plant polyphenols may be an important mechanism for their anticancer properties

  17. Efficient degradation of atrazine by magnetic porous copper ferrite catalyzed peroxymonosulfate oxidation via the formation of hydroxyl and sulfate radicals.

    Science.gov (United States)

    Guan, Ying-Hong; Ma, Jun; Ren, Yue-Ming; Liu, Yu-Lei; Xiao, Jia-Yue; Lin, Ling-qiang; Zhang, Chen

    2013-09-15

    Magnetic porous copper ferrite (CuFe2O4) showed a notable catalytic activity to peroxymonosulfate (PMS). More than 98% of atrazine was degraded within 15 min at 1 mM PMS and 0.1 g/L CuFe2O4. In contrast, CuFe2O4 exhibited no obvious catalytic activity to peroxodisulfate or H2O2. Several factors affecting the catalytic performance of PMS/CuFe2O4 were investigated. Results showed that the catalytic degradation efficiency of atrazine increased with PMS and CuFe2O4 doses, but decreased with the increase of natural organic matters concentration. The catalytic oxidation also showed a dependence on initial pH. The presence of bicarbonate stimulated atrazine degradation by PMS/CuFe2O4 at low concentrations but inhibited the degradation at high concentrations. Furthermore, the reactive species for atrazine degradation in PMS/CuFe2O4 system were identified as hydroxyl radical (HO) and sulfate radical (SO4(·-)) through competition reactions of atrazine and nitrobenzene, instead of commonly used alcohol scavenging, which was not a reliable method in metal oxide catalyzed oxidation. Surface hydroxyl groups of CuFe2O4 were a critical part in radical generation and the copper on CuFe2O4 surface was an active site to catalyze PMS. The catalytic degradation of atrazine by PMS/CuFe2O4 was also effective under the background of actual waters.

  18. Expression of a nitric oxide degrading enzyme induces a senescence programme in Arabidopsis.

    Science.gov (United States)

    Mishina, Tatiana E; Lamb, Chris; Zeier, Jürgen

    2007-01-01

    Nitric oxide (NO) has been proposed to act as a factor delaying leaf senescence and fruit maturation in plants. Here we show that expression of a NO degrading dioxygenase (NOD) in Arabidopsis thaliana initiates a senescence-like phenotype, an effect that proved to be more pronounced in older than in younger leaves. This senescence phenotype was preceded by a massive switch in gene expression in which photosynthetic genes were down-regulated, whereas many senescence-associated genes (SAGs) and the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene ACS6 involved in ethylene synthesis were up-regulated. External fumigation of NOD plants with NO as well as environmental conditions known to stimulate endogenous NO production attenuated the induced senescence programme. For instance, both high light conditions and nitrate feeding reduced the senescence phenotype and attenuated the down-regulation of photosynthetic genes as well as the up-regulation of SAGs. Treatment of plants with the cytokinin 6-benzylaminopurin (BAP) reduced the down-regulation of photosynthesis, although it had no consistent effect on SAG expression. Metabolic changes during NOD-induced senescence comprehended increases in salicylic acid (SA) levels, accumulation of the phytoalexin camalexin and elevation of leaf gamma-tocopherol contents, all of which occurred during natural senescence in Arabidopsis leaves as well. Moreover, NO fumigation delayed the senescence process induced by darkening individual Arabidopsis Columbia-0 (Col-0) leaves. Our data thus support the notion that NO acts as a negative regulator of leaf senescence.

  19. Chronic oxidative stress promotes H2AX protein degradation and enhances chemosensitivity in breast cancer patients.

    Science.gov (United States)

    Gruosso, Tina; Mieulet, Virginie; Cardon, Melissa; Bourachot, Brigitte; Kieffer, Yann; Devun, Flavien; Dubois, Thierry; Dutreix, Marie; Vincent-Salomon, Anne; Miller, Kyle Malcolm; Mechta-Grigoriou, Fatima

    2016-01-01

    Anti-cancer drugs often increase reactive oxygen species (ROS) and cause DNA damage. Here, we highlight a new cross talk between chronic oxidative stress and the histone variant H2AX, a key player in DNA repair. We observe that persistent accumulation of ROS, due to a deficient JunD-/Nrf2-antioxidant response, reduces H2AX protein levels. This effect is mediated by an enhanced interaction of H2AX with the E3 ubiquitin ligase RNF168, which is associated with H2AX poly-ubiquitination and promotes its degradation by the proteasome. ROS-mediated H2AX decrease plays a crucial role in chemosensitivity. Indeed, cycles of chemotherapy that sustainably increase ROS reduce H2AX protein levels in Triple-Negative breast cancer (TNBC) patients. H2AX decrease by such treatment is associated with an impaired NRF2-antioxidant response and is indicative of the therapeutic efficiency and survival of TNBC patients. Thus, our data describe a novel ROS-mediated regulation of H2AX turnover, which provides new insights into genetic instability and treatment efficacy in TNBC patients. PMID:27006338

  20. Enhanced catalytic oxidation ability of ternary layered double hydroxides for organic pollutants degradation.

    Science.gov (United States)

    Fahel, Jean; Kim, Sanghoon; Durand, Pierrick; André, Erwan; Carteret, Cédric

    2016-05-10

    Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants. PMID:27097543

  1. Acetone Extract of Almond Hulls Provides Protection against Oxidative Damage and Membrane Protein Degradation.

    Science.gov (United States)

    Meshkini, Azadeh

    2016-06-01

    Several studies have revealed that among foods, the consumption of edible nuts has beneficial effects on health which are attributed to their high content of potent antioxidants. Among nuts, the whole seed of the almond (Prunus dulcis) has been demonstrated to possess potent free radical scavenging activity, which is related to the presence of phenolic compounds. The aim of the current study is to evaluate the polyphenol content and the antioxidant ability of almond hull, which is an agriculture solid waste. The present results revealed that among different extraction methods, the acetone extract of almond hulls has a high content of phenolic and flavonoid compounds and a high antioxidant ability, which were determined by using the phosphomolybdenum method and by measuring the potency of the antioxidant, respectively. Moreover, the experimental data disclosed that the acetone extract of almond hulls provides protection against the oxidative damage and the membrane protein degradation that are caused in human erythrocytes by hydrogen peroxide. These phenomena may likely be due to the recruitment of antioxidants by cell membranes and/or translocation to cytosol. Overall, almond hull extract could be considered as a natural source of antioxidants, and its consumption could have a positive effect on human health. PMID:27342887

  2. Combined technology for clomazone herbicide wastewater treatment: three-dimensional packed-bed electrochemical oxidation and biological contact degradation.

    Science.gov (United States)

    Feng, Yujie; Liu, Junfeng; Zhu, Limin; Wei, Jinzhi

    2013-01-01

    The clomazone herbicide wastewater was treated using a combined technology composed of electrochemical catalytic oxidation and biological contact degradation. A new type of electrochemical reactor was fabricated and a Ti/SnO2 electrode was chosen as the anode in electrochemical-oxidation reactor and stainless steel as the cathode. Ceramic rings loaded with SnO2 were used as three-dimensional electrodes forming a packed bed. The operation parameters that might influence the degradation of organic contaminants in the clomazone wastewater were optimized. When the cell voltage was set at 30 V and the volume of particle electrodes was designed as two-thirds of the volume of the total reactor bed, the chemical oxygen demand (COD) removal rate could reach 82% after 120 min electrolysis, and the ratio of biochemical oxygen demand (BOD)/COD of wastewater increased from 0.12 to 0.38. After 12 h degradation with biological contact oxidation, the total COD removal rate of the combined technology reached 95%, and effluent COD was below 120 mg/L. The results demonstrated that this electrocatalytic oxidation method can be used as a pretreatment for refractory organic wastewater before biological treatment.

  3. Degradation mechanisms in solid oxide electrolysis anodes: Cr poisoning and cation interdiffusion

    International Nuclear Information System (INIS)

    High temperature steam electrolysis is one of the most efficient processes for hydrogen generation from water with no CO2 emissions using electricity and heat from nuclear or concentrated solar plants. Solid Oxide Electrolytic Cells (SOEC) are the proposed technology being researched and developed for this purpose. Over a long period of operation of the cells, various sources for degradation in the cells' electrochemical performance prevail, and hence the cell resistance increases and the process becomes inefficient. Our research is aimed at identifying the mechanisms for the loss in the electrochemical performance of the cell, particularly of the oxygen electrode, namely the anode. We are performing post-mortem analysis of the anode materials from SOEC stacks that were subject to demonstration tests over 2000 hours. We are focusing on two mechanisms of degradation: i) on the diffusion and reaction of chromium from the stainless steel interconnects onto the bond layer (cobaltite) and electrode (manganite) surface; ii) inter-diffusion of electrode and composite cations dissociating the anode composition. Chromium penetrates into the electrode microstructure through vapour-phase or solid state transport and reacts with the electrode material to form secondary and inactive phases which block the active sites. We have employed Raman Spectroscopy and identified the secondary phases, on the surface of the bong layer, that include mainly Cr2O3, LaCrO3, La2O3 and Co3O4, which have much lower conductivity than the original perovskite structure. We used scanning Auger Electron Nano-spectroscopy (AES) to study the local variations in the air electrode and the bond layer microchemistry and microstructure on a nano-to-micron scale. Chromium was clearly seen to be present in the cobaltite bond layer, and the chromium content was observed to monotonically decrease along the thickness of the bond layer. The manganite and manganite/zirconia composite electrode layers did not

  4. Fenton法降解水中布洛芬%Degradation of ibuprofen by Fenton oxidation

    Institute of Scientific and Technical Information of China (English)

    杨丽娟; 胡翔; 吴晓楠

    2012-01-01

    采用benton法降解水中布洛芬,考察了H2O2投加量、FeSO4·7H2O与H2O2的比值、初始pH、反应时间等因素对布洛芬去除率的影响,通过正交实验确定影响作用大小依次为:[Fe2+]:[H2O2]的物质的量之比〉H2O2的投加量〉pH值,最佳的反应工艺条件为:H2O2的投加量为3mL-L1,[Fe2+]:[H2O2]的物质的量之比为1:10,反应初始pH值为3,反应时间为40min.在最佳条件下布洛芬的去除率达到86%以上.同时对布洛芬降解反应动力学进行了研究,发现Fenton降解布洛芬符合二级反应动力学规律.%The degradation of ibuprofen was investigated by using Fenton method. The effects of different tactors on the removal efficiency of ibuprofen were evaluated. The order of main factors were O O rthogo ptimal nal experiments as follow: the mole ratio of Fe2+ to H2O2 〉 H2O2 dosage 〉 reaction conditions were as follow : dosage of H2O2 was 3 mL. L- 1, the mole ratio 1 : 10, the initial pH was 3 and the reaction time was 40 min. Under such conditions, the ibuprofen was over 86%. The reaction kinetics was also investigated. The degradation of oxidation was accord with the second order kinetics.

  5. Oxidative modifications, mitochondrial dysfunction, and impaired protein degradation in Parkinson's disease: how neurons are lost in the Bermuda triangle

    Directory of Open Access Journals (Sweden)

    Malkus Kristen A

    2009-06-01

    Full Text Available Abstract While numerous hypotheses have been proposed to explain the molecular mechanisms underlying the pathogenesis of neurodegenerative diseases, the theory of oxidative stress has received considerable support. Although many correlations have been established and encouraging evidence has been obtained, conclusive proof of causation for the oxidative stress hypothesis is lacking and potential cures have not emerged. Therefore it is likely that other factors, possibly in coordination with oxidative stress, contribute to neuron death. Using Parkinson's disease (PD as the paradigm, this review explores the hypothesis that oxidative modifications, mitochondrial functional disruption, and impairment of protein degradation constitute three interrelated molecular pathways that execute neuron death. These intertwined events are the consequence of environmental exposure, genetic factors, and endogenous risks and constitute a "Bermuda triangle" that may be considered the underlying cause of neurodegenerative pathogenesis.

  6. Protective role of Cys-178 against the inactivation and oligomerization of human insulin-degrading enzyme by oxidation and nitrosylation.

    Science.gov (United States)

    Ralat, Luis A; Ren, Min; Schilling, Alexander B; Tang, Wei-Jen

    2009-12-01

    Insulin-degrading enzyme (IDE), a 110-kDa metalloendopeptidase, hydrolyzes several physiologically relevant peptides, including insulin and amyloid-beta (Abeta). Human IDE has 13 cysteines and is inhibited by hydrogen peroxide and S-nitrosoglutathione (GSNO), donors of reactive oxygen and nitrogen species, respectively. Here, we report that the oxidative burst of BV-2 microglial cells leads to oxidation or nitrosylation of secreted IDE, leading to the reduced activity. Hydrogen peroxide and GSNO treatment of IDE reduces the V(max) for Abeta degradation, increases IDE oligomerization, and decreases IDE thermostability. Additionally, this inhibitory response of IDE is substrate-dependent, biphasic for Abeta degradation but monophasic for a shorter bradykinin-mimetic substrate. Our mutational analysis of IDE and peptide mass fingerprinting of GSNO-treated IDE using Fourier transform-ion cyclotron resonance mass spectrometer reveal a surprising interplay of Cys-178 with Cys-110 and Cys-819 for catalytic activity and with Cys-789 and Cys-966 for oligomerization. Cys-110 is near the zinc-binding catalytic center and is normally buried. The oxidation and nitrosylation of Cys-819 allow Cys-110 to be oxidized or nitrosylated, leading to complete inactivation of IDE. Cys-789 is spatially adjacent to Cys-966, and their nitrosylation and oxidation together trigger the oligomerization and inhibition of IDE. Interestingly, the Cys-178 modification buffers the inhibition caused by Cys-819 modification and prevents the oxidation or nitrosylation of Cys-110. The Cys-178 modification can also prevent the oligomerization-mediated inhibition. Thus, IDE can be intricately regulated by reactive oxygen or nitrogen species. The structure of IDE reveals the molecular basis for the long distance interactions of these cysteines and how they regulate IDE function.

  7. Protective Role of Cys-178 against the Inactivation and Oligomerization of Human Insulin-degrading Enzyme by Oxidation and Nitrosylation*

    Science.gov (United States)

    Ralat, Luis A.; Ren, Min; Schilling, Alexander B.; Tang, Wei-Jen

    2009-01-01

    Insulin-degrading enzyme (IDE), a 110-kDa metalloendopeptidase, hydrolyzes several physiologically relevant peptides, including insulin and amyloid-β (Aβ). Human IDE has 13 cysteines and is inhibited by hydrogen peroxide and S-nitrosoglutathione (GSNO), donors of reactive oxygen and nitrogen species, respectively. Here, we report that the oxidative burst of BV-2 microglial cells leads to oxidation or nitrosylation of secreted IDE, leading to the reduced activity. Hydrogen peroxide and GSNO treatment of IDE reduces the Vmax for Aβ degradation, increases IDE oligomerization, and decreases IDE thermostability. Additionally, this inhibitory response of IDE is substrate-dependent, biphasic for Aβ degradation but monophasic for a shorter bradykinin-mimetic substrate. Our mutational analysis of IDE and peptide mass fingerprinting of GSNO-treated IDE using Fourier transform-ion cyclotron resonance mass spectrometer reveal a surprising interplay of Cys-178 with Cys-110 and Cys-819 for catalytic activity and with Cys-789 and Cys-966 for oligomerization. Cys-110 is near the zinc-binding catalytic center and is normally buried. The oxidation and nitrosylation of Cys-819 allow Cys-110 to be oxidized or nitrosylated, leading to complete inactivation of IDE. Cys-789 is spatially adjacent to Cys-966, and their nitrosylation and oxidation together trigger the oligomerization and inhibition of IDE. Interestingly, the Cys-178 modification buffers the inhibition caused by Cys-819 modification and prevents the oxidation or nitrosylation of Cys-110. The Cys-178 modification can also prevent the oligomerization-mediated inhibition. Thus, IDE can be intricately regulated by reactive oxygen or nitrogen species. The structure of IDE reveals the molecular basis for the long distance interactions of these cysteines and how they regulate IDE function. PMID:19808678

  8. Degradation behavior of anode-supported solid oxide fuel cell using LNF cathode as function of current load

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Takeshi; Yoshida, Yoshiteru; Watanabe, Kimitaka; Chiba, Reiichi; Taguchi, Hiroaki; Orui, Himeko; Arai, Hajime [NTT Energy and Environment Systems Laboratories, Atsugi-shi, Kanagawa 243-0198 (Japan)

    2010-09-01

    We investigated the effect of current loading on the degradation behavior of an anode-supported solid oxide fuel cell (SOFC). The cell consisted of LaNi{sub 0.6}Fe{sub 0.4}O{sub 3} (LNF), alumina-doped scandia stabilized zirconia (SASZ), and a Ni-SASZ cermet as the cathode, electrolyte, and anode, respectively. The test was carried out at 1073 K with constant loads of 0.3, 1.0, 1.5, and 2.3 A cm{sup -2}. The degradation rate, defined by the voltage loss during a fixed period (about 1000 h), was faster at higher current densities. From an impedance analysis, the degradation depended mainly on increases in the cathodic resistance, while the anodic and ohmic resistances contributed very little. The cathode microstructures were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). (author)

  9. Biodegradation of Benzo[a]pyrene by Arthrobacter oxydans B4

    Institute of Scientific and Technical Information of China (English)

    PENG Hui; YIN Hua; DENG Jun; YE Jin-Shao; CHEN Shuo-Na; HE Bao-Yan; ZHANG Na

    2012-01-01

    A bacterial strain,Arthrobacter oxydans (B4),capable of degrading benzo[a]pyrene (BaP) in water body,was isolated from a polycyclic aromatic hydrocarbons-contaminated site.Effects of different factors,such as reaction time,pH value,temperature and organic nutrients,on BaP biodegradation by the strain B4 were studied.After 5 d treatment,the concentration of BaP in mineral salts medium was reduced to 0.318 mg L-1,compared to the initial concentration of 1.000 mg L-1.There was a process of acid formation during the degradation with pH failing from initial 7.01 to 4.61 at 5 d,so keeping the water body under slightly alkaline condition was propitious to BaP degradation.Strain B4 efficiently degraded BaP at 20 to 37 ℃ with addition of organic nutrients.The biodegradation and transformation of BaP mainly occurred on cell surfaces,and extracellular secretions played an important role in these processes.Fourier transform infrared spectroscopy and gas chromatograph-mass spectrometer analyses of metabolites showed that ring cleavage occurred in the BaP degradation process and the resulting metabolically utilizable substrates were generated as sole carbon sources for B4 growth.Furthermore,mineralization extent of metabolites was verified by determining the total organic carbon and inorganic carbon in the degradation system.

  10. Computational consideration on advanced oxidation degradation of phenolic preservative, methylparaben, in water: mechanisms, kinetics, and toxicity assessments

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Computational approach is effective to reveal the transformation mechanism of MPB. • MPB degradation was more dependent on the [• OH] than temperature during AOPs. • O2 could enhance MPB degradation, but more harmful products were formed. • The risks of MPB products in natural waters should be considered seriously. • The risks of MPB products can be overlooked in AOPs due to short half-time. - Abstract: Hydroxyl radicals (• OH) are strong oxidants that can degrade organic pollutants in advanced oxidation processes (AOPs). The mechanisms, kinetics, and toxicity assessment of the • OH-initiated oxidative degradation of the phenolic preservative, methylparaben (MPB), were systematically investigated using a computational approach, as the supplementary information for experimental data. Results showed that MPB can be initially attacked by • OH via OH-addition and H-abstraction routes. Among these routes, the • OH addition to the C atom at the ortho-position of phenolic hydroxyl group was the most significant route. However, the methyl-H-abstraction route also cannot be neglected. Further, the formed transient intermediates, OH-adduct (• MPB-OH1) and dehydrogenated radical (• MPB(-H)α), could be easily transformed to several stable degradation products in the presence of O2 and • OH. To better understand the potential toxicity of MPB and its products to aquatic organisms, both acute and chronic toxicities were assessed computationally at three trophic levels. Both MPB and its products, particularly the OH-addition products, are harmful to aquatic organisms. Therefore, the application of AOPs to remove MPB should be carefully performed for safe water treatment

  11. Computational consideration on advanced oxidation degradation of phenolic preservative, methylparaben, in water: mechanisms, kinetics, and toxicity assessments

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yanpeng [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); An, Taicheng, E-mail: antc99@gig.ac.cn [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Fang, Hansun [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ji, Yuemeng; Li, Guiying [State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2014-08-15

    Graphical abstract: - Highlights: • Computational approach is effective to reveal the transformation mechanism of MPB. • MPB degradation was more dependent on the [{sup •} OH] than temperature during AOPs. • O{sub 2} could enhance MPB degradation, but more harmful products were formed. • The risks of MPB products in natural waters should be considered seriously. • The risks of MPB products can be overlooked in AOPs due to short half-time. - Abstract: Hydroxyl radicals ({sup •} OH) are strong oxidants that can degrade organic pollutants in advanced oxidation processes (AOPs). The mechanisms, kinetics, and toxicity assessment of the {sup •} OH-initiated oxidative degradation of the phenolic preservative, methylparaben (MPB), were systematically investigated using a computational approach, as the supplementary information for experimental data. Results showed that MPB can be initially attacked by {sup •} OH via OH-addition and H-abstraction routes. Among these routes, the {sup •} OH addition to the C atom at the ortho-position of phenolic hydroxyl group was the most significant route. However, the methyl-H-abstraction route also cannot be neglected. Further, the formed transient intermediates, OH-adduct ({sup •} MPB-OH{sub 1}) and dehydrogenated radical ({sup •} MPB(-H)α), could be easily transformed to several stable degradation products in the presence of O{sub 2} and {sup •} OH. To better understand the potential toxicity of MPB and its products to aquatic organisms, both acute and chronic toxicities were assessed computationally at three trophic levels. Both MPB and its products, particularly the OH-addition products, are harmful to aquatic organisms. Therefore, the application of AOPs to remove MPB should be carefully performed for safe water treatment.

  12. Electrochemical degradation of Reactive Brilliant Red K-2BP on Ti/RuTiIrSnMn oxide anode in a batch cell

    Directory of Open Access Journals (Sweden)

    LUO JIANCHENG

    2012-11-01

    Full Text Available Electrochemical degradation of Reactive Brilliant Red K-2BP on Ti/RuTiIrSnMn oxide anode in chloride containing solution was investigated by voltammetry and electrolysis in a batch cell. It is found that the degradation mechanism of K-2BP on Ti/RuTiIrSnMn oxide anode involves an indirect electrocatalytic oxidation, in which K-2BP is oxidized by the electrochemically generated active chlorine. This degradation reaction follows pseudo-first order reaction kinetics. Ti/RuTiIrSnMn oxide exhibits excellent electrocata­lytic activity toward the generation of active chlorine from chloride. Hence, K-2BP can be electrochemically degraded effectively in chloride containing solution. The decolorization efficiency was found to increase with the decrease in pH and with the increase in current density, NaCl concentration, temperature, and flow rate of the solution.

  13. BENZO[a]PYRENE METABOLITES EXAGGERATE DNA OXIDATIVE DAMAGE UPON THE INVOLVEMENT OF FREE RADICALS%苯并[a]比代谢产物在自由基参与下加速DNA的氧化损伤

    Institute of Scientific and Technical Information of China (English)

    罗云敬; GAO Da-yuan; WEI Hua-chen

    2003-01-01

    @@ Polycyclic aromatic hydrocarbons (PAHs),which constitute a major class of environmental pollu tants are posing a threat to human health. Benzopyrene,an index of PAH levels omnipresent in the everyday environment ,becomes toxic only when being metabolically and/or photo-activated,i. e. ,in the pres ence of UV light. Free radicals such as superoxide anions ('O2),hydrogen peroxide (H2O2),hydroxyl radicals ('OH) and singlet oxygen (1O2) are involved in carcinogenesis. Wei CE etc[1] studied the effects of different scavengers of active oxygen species (superoxide dismutase,catalase,mannitol and dimethyfu ran) on promoting B[a]P mutagenicity. Bryla P ete[2] investigated the roles of several ROS scavengers in the oxidation and binding of B[a]P to calf thymus DNA using the 32p-postlabeling assay.

  14. Fundamental degradation mechanisms of layered oxide Li-ion battery cathode materials: Methodology, insights and novel approaches

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Description of recent in operando and in situ analysis methodology. • Surface science approach using photoemission for analysis of cathode surfaces and interfaces. • Ageing and fatigue of layered oxide Li-ion battery cathode materials from the atomistic point of view. • Defect formation and electronic structure evolution as causes for cathode degradation. • Significance of interfacial energy alignment and contact potential for side reactions. - Abstract: This overview addresses the atomistic aspects of degradation of layered LiMO2 (M = Ni, Co, Mn) oxide Li-ion battery cathode materials, aiming to shed light on the fundamental degradation mechanisms especially inside active cathode materials and at their interfaces. It includes recent results obtained by novel in situ/in operando diffraction methods, modelling, and quasi in situ surface science analysis. Degradation of the active cathode material occurs upon overcharge, resulting from a positive potential shift of the anode. Oxygen loss and eventual phase transformation resulting in dead regions are ascribed to changes in electronic structure and defect formation. The anode potential shift results from loss of free lithium due to side reactions occurring at electrode/electrolyte interfaces. Such side reactions are caused by electron transfer, and depend on the electron energy level alignment at the interface. Side reactions at electrode/electrolyte interfaces and capacity fade may be overcome by the use of suitable solid-state electrolytes and Li-containing anodes

  15. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

    Science.gov (United States)

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-07-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

  16. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition Oxidation; Surface degradation

    CERN Document Server

    Simcock, M N

    2002-01-01

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an inte...

  17. Unravelling the Interactions between Hydrolytic and Oxidative Enzymes in Degradation of Lignocellulosic Biomass by Sporothrix carnis under Various Fermentation Conditions.

    Science.gov (United States)

    Ogunyewo, Olusola A; Olajuyigbe, Folasade M

    2016-01-01

    The mechanism underlying the action of lignocellulolytic enzymes in biodegradation of lignocellulosic biomass remains unclear; hence, it is crucial to investigate enzymatic interactions involved in the process. In this study, degradation of corn cob by Sporothrix carnis and involvement of lignocellulolytic enzymes in biodegradation were investigated over 240 h cultivation period. About 60% degradation of corn cob was achieved by S. carnis at the end of fermentation. The yields of hydrolytic enzymes, cellulase and xylanase, were higher than oxidative enzymes, laccase and peroxidase, over 144 h fermentation period. Maximum yields of cellulase (854.4 U/mg) and xylanase (789.6 U/mg) were at 96 and 144 h, respectively. Laccase and peroxidase were produced cooperatively with maximum yields of 489.06 U/mg and 585.39 U/mg at 144 h. Drastic decline in production of cellulase at 144 h (242.01 U/mg) and xylanase at 192 h (192.2 U/mg) indicates that they play initial roles in biodegradation of lignocellulosic biomass while laccase and peroxidase play later roles. Optimal degradation of corn cob (76.6%) and production of hydrolytic and oxidative enzymes were achieved with 2.5% inoculum at pH 6.0. Results suggest synergy in interactions between the hydrolytic and oxidative enzymes which can be optimized for improved biodegradation. PMID:26881077

  18. Unravelling the Interactions between Hydrolytic and Oxidative Enzymes in Degradation of Lignocellulosic Biomass by Sporothrix carnis under Various Fermentation Conditions

    Directory of Open Access Journals (Sweden)

    Olusola A. Ogunyewo

    2016-01-01

    Full Text Available The mechanism underlying the action of lignocellulolytic enzymes in biodegradation of lignocellulosic biomass remains unclear; hence, it is crucial to investigate enzymatic interactions involved in the process. In this study, degradation of corn cob by Sporothrix carnis and involvement of lignocellulolytic enzymes in biodegradation were investigated over 240 h cultivation period. About 60% degradation of corn cob was achieved by S. carnis at the end of fermentation. The yields of hydrolytic enzymes, cellulase and xylanase, were higher than oxidative enzymes, laccase and peroxidase, over 144 h fermentation period. Maximum yields of cellulase (854.4 U/mg and xylanase (789.6 U/mg were at 96 and 144 h, respectively. Laccase and peroxidase were produced cooperatively with maximum yields of 489.06 U/mg and 585.39 U/mg at 144 h. Drastic decline in production of cellulase at 144 h (242.01 U/mg and xylanase at 192 h (192.2 U/mg indicates that they play initial roles in biodegradation of lignocellulosic biomass while laccase and peroxidase play later roles. Optimal degradation of corn cob (76.6% and production of hydrolytic and oxidative enzymes were achieved with 2.5% inoculum at pH 6.0. Results suggest synergy in interactions between the hydrolytic and oxidative enzymes which can be optimized for improved biodegradation.

  19. Mechanisms Underpinning Degradation of Protective Oxides and Thermal Barrier Coatings in High Hydrogen Content (HHC) - Fueled Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mumm, Daniel

    2013-08-31

    The overarching goal of this research program has been to evaluate the potential impacts of coal-derived syngas and high-hydrogen content fuels on the degradation of turbine hot-section components through attack of protective oxides and thermal barrier coatings. The primary focus of this research program has been to explore mechanisms underpinning the observed degradation processes, and connections to the combustion environments and characteristic non-combustible constituents. Based on the mechanistic understanding of how these emerging fuel streams affect materials degradation, the ultimate goal of the program is to advance the goals of the Advanced Turbine Program by developing materials design protocols leading to turbine hot-section components with improved resistance to service lifetime degradation under advanced fuels exposures. This research program has been focused on studying how: (1) differing combustion environments – relative to traditional natural gas fired systems – affect both the growth rate of thermally grown oxide (TGO) layers and the stability of these oxides and of protective thermal barrier coatings (TBCs); and (2) how low levels of fuel impurities and characteristic non-combustibles interact with surface oxides, for instance through the development of molten deposits that lead to hot corrosion of protective TBC coatings. The overall program has been comprised of six inter-related themes, each comprising a research thrust over the program period, including: (i) evaluating the role of syngas and high hydrogen content (HHC) combustion environments in modifying component surface temperatures, heat transfer to the TBC coatings, and thermal gradients within these coatings; (ii) understanding the instability of TBC coatings in the syngas and high hydrogen environment with regards to decomposition, phase changes and sintering; (iii) characterizing ash deposition, molten phase development and infiltration, and associated corrosive

  20. Thermal degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) over synthesized Fe-Al composite oxide.

    Science.gov (United States)

    Yang, Fan; Li, Qianqian; Su, Guijin; Huang, Xinchen; Li, Binke; Zhao, Yanhui; Miao, Xue; Zheng, Minghui

    2016-05-01

    A series of Fe-Al composite oxides were synthesized by the hydrothermal method using different urea dosages and examined towards the degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) at 300 °C. The as-prepared oxides were characterized by field-emission scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. The morphology and composition of the prepared materials could be regulated by controlling the urea concentration. Interestingly, these properties influenced the nature and amount of the hydrodebromination products generated during the degradation of BDE-47. The degradation of BDE-47 over the composite oxide prepared at a urea dosage of 3 mmol generated BDE-17 as the major isomer product, followed by BDE-28/33, -30, and -32, among the tribromodiphenyl ethers (tri-BDEs). Regarding the dibromodiphenyl ethers (di-BDEs) produced, the amount of the isomers decreased in the order of BDE-8/11 > BDE-7 > BDE-15 > BDE-10. And the BDE-1 among monobromodiphenyl was determined. In contrast, over the composite oxides prepared at urea dosages greater than 3 mmol, BDE-28/33 gradually become the major isomer product instead of BDE-17 among tri-BDEs. The amount of the other di-BDEs isomer such as BDE-15 and -10 approach to be comparable to that BDE-8/11. However, regardless of the urea dosage, BDE-47 converted into BDE-75 via an isomerization reaction. Based on these intermediate products identification, a possible hydrodebromination mechanism of BDE-47 over Fe-Al composite oxide was comprehensively traced.

  1. Simazine degradation in bioaugmented soil: urea impact and response of ammonia-oxidizing bacteria and other soil bacterial communities.

    Science.gov (United States)

    Guo, Qingwei; Wan, Rui; Xie, Shuguang

    2014-01-01

    The objective of this study was to investigate the impact of exogenous urea nitrogen on ammonia-oxidizing bacteria (AOB) and other soil bacterial communities in soil bioaugmented for simazine remediation. The previously isolated simazine-degrading Arthrobacter sp. strain SD1 was used to degrade the herbicide. The effect of urea on the simazine degradation capacity of the soil bioaugmented with Arthrobacter strain SD1 was assessed using quantitative PCR targeting the s-triazine-degrading trzN and atzC genes. Structures of bacterial and AOB communities were characterized using terminal restriction fragment length polymorphism. Urea fertilizer could affect simazine biodegradation and decreased the proportion of its trzN and atzC genes in soil augmented with Arthrobacter strain SD1. Bioaugmentation process could significantly alter the structures of both bacterial and AOB communities, which were strongly affected by urea amendment, depending on the dosage. This study could provide some new insights towards s-triazine bioremediation and microbial ecology in a bioaugmented system. However, further studies are necessary in order to elucidate the impact of different types and levels of nitrogen sources on s-triazine-degraders and bacterial and AOB communities in bioaugmented soil.

  2. A study into the impact of interface roughness development on mechanical degradation of oxides formed on zirconium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Platt, P. [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom); Wedge, S. [AMEC, Walton House, Faraday Street, Birchwood Park, Risley, Warrington WA3 6GA (United Kingdom); Frankel, P. [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom); Gass, M.; Howells, R. [AMEC, Walton House, Faraday Street, Birchwood Park, Risley, Warrington WA3 6GA (United Kingdom); Preuss, M. [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom)

    2015-04-15

    As a cladding material used to encapsulate nuclear fuel pellets, zirconium alloys are the primary barrier separating the fuel and a pressurised steam or lithiated water environment. Degradation mechanisms such as oxidation can be the limiting factor in the life-time of the fuel assembly. Key to controlling oxidation, and therefore allowing increased burn-up of fuel, is the development of a mechanistic understanding of the corrosion process. In an autoclave, the oxidation kinetics for zirconium alloys are typically cyclical, with periods of accelerated kinetics being observed in steps of ∼2 μm oxide growth. These periods of accelerated oxidation are immediately preceded by the development of a layer of lateral cracks near the metal-oxide interface, which may be associated with the development of interface roughness. The present work uses scanning electron microscopy to carry out a statistical analysis of changes in the metal-oxide interface roughness between three different alloys at different stages of autoclave oxidation. The first two alloys are Zircaloy-4 and ZIRLO{sup ™} for which analysis is carried out at stages before, during and after first transition. The third alloy is an experimental low tin alloy, which under the same oxidation conditions and during the same time period does not appear to go through transition. Assessment of the metal-oxide interface roughness is primarily carried out based on the root mean square of the interface slope known as the R{sub dq} parameter. Results show clear trends with relation to transition points in the corrosion kinetics. Discussion is given to how this relates to the existing mechanistic understanding of the corrosion process, and the components required for possible future modelling approaches.

  3. Quantitative review of degradation and lifetime of solid oxide cells and stacks

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Hjelm, Johan; Blennow, Peter;

    2016-01-01

    and lifetime in the field. The data is used to visualizespecific trends regarding choice of materials, operating conditions and degradation rates.The average degradation rate reported is decreasing and is quickly approaching officialtargets. The database is published online for open-access and a continued...

  4. Dark ambient degradation of Bisphenol A and Acid Orange 8 as organic pollutants by perovskite SrFeO{sub 3−δ} metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Leiw, Ming Yian, E-mail: LEIW0003@e.ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); Guai, Guan Hong [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); School of Chemical and Biomedical Engineering and Center for Advanced Bionanosystems, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457 (Singapore); Wang, Xiaoping [School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Tse, Man Siu [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Ng, Chee Mang [GlobalFoundries Singapore Pte. Ltd., 60 Woodlands Industrial Park D Street 2, Singapore 738406 (Singapore); Tan, Ooi Kiang [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2013-09-15

    Highlights: • Perovskite SFO prepared by high temperature and high-energy ball milling process. • SFO metal oxide shows good efficiency in degrading and mineralizing BPA. • Rapid decoloration of AO8 was achieved in the presence of SFO metal oxide. • O{sub 2}·{sup −} is the predominant ROS for dark oxidative degradation of BPA and AO8. -- Abstract: Current advanced oxidation processes (AOPs) are chemically and energetically intensive processes, which are undesirable for cost-effective and large-scale system water treatment and wastewater recycling. This study explored the Strontium Ferrite (SFO) metal oxide on the degradation of highly concentrated organic pollutants under dark ambient condition without any external stimulants. The SFO particles with single perovskite structure were successfully synthesized with a combined high temperature and high-energy ball milling process. An endocrine disruptor, Bisphenol A (BPA) and an azo dye, Acid Orange 8 (AO8) were used as probe organic pollutants. BPA was completely degraded with 83% of mineralization in 24 h while rapid decoloration of AO8 was achieved in 60 min and complete breakdown into primary intermediates and aliphatic acids occurred in 24 h under the treatment of dispersed SFO metal oxide in water. Such efficient degradation could be attributed to the enhanced adsorption of these anionic pollutants on positively charged ball-milled SFO metal oxide surface, resulted in higher degradation activity. Preliminary degradation mechanisms of BPA and AO8 under the action of SFO metal oxide were proposed. These results showed that the SFO metal oxide could be an efficient alternative material as novel advanced oxidation technology for low cost water treatment.

  5. Synthesize of Graphene-Tin Oxide Nanocomposite and Its Photocatalytic Properties for the Degradation of Organic Pollutants Under Visible Light.

    Science.gov (United States)

    Shanmugam, M; Jayavel, R

    2015-09-01

    Graphene-tinoxide nanocomposite has been synthesised by coating SnO2 nanoparticles on graphene sheets by the redox reaction between graphene oxide (GO) and tin chloride. Graphene oxide was reduced to graphene and Sn2+ was oxidized to SnO2 during the redox reaction, resulting in the uniform distribution of SnO2 nanoparticles on graphene sheets. The synthesised material was characterized by XRD, SEM, AFM, FT-IR, UV-vis, TGA and Raman spectroscopic studies. SEM and AFM studies reveal the formation of wrinkled paper like structure of graphene sheets with uniform coating of SnO2 nanoparticles on either side. The strong photocatalytic degradation of Methylene orange (MO) dye was analysed using G-SnO2 nanocomposite under the visible light irradiation. PMID:26716310

  6. Degradation of cytokinins by maize cytokinin dehydrogenase is mediated by free radicals generated by enzymatic oxidation of natural benzoxazinones.

    Science.gov (United States)

    Frébortová, Jitka; Novák, Ondrej; Frébort, Ivo; Jorda, Radek

    2010-02-01

    Hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-one (DIMBOA) was isolated from maize phloem sap as a compound enhancing the degradation of isopentenyl adenine by maize cytokinin dehydrogenase (CKX), after oxidative conversion by either laccase or peroxidase. Laccase and peroxidase catalyze oxidative cleavage of DIMBOA to 4-nitrosoresorcinol-1-monomethyl ether (coniferron), which serves as a weak electron acceptor of CKX. The oxidation of DIMBOA and coniferron generates transitional free radicals that are used by CKX as effective electron acceptors. The function of free radicals in the CKX-catalyzed reaction was also verified with a stable free radical of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid. Application of exogenous cytokinin to maize seedlings resulted in an enhanced benzoxazinoid content in maize phloem sap. The results indicate a new function for DIMBOA in the metabolism of the cytokinin group of plant hormones. PMID:19912568

  7. Atmospheric fate of OH initiated oxidation of terpenes. Reaction mechanism of alpha-pinene degradation and secondary organic aerosol formation.

    Science.gov (United States)

    Librando, Vito; Tringali, Giuseppe

    2005-05-01

    This paper studies the reaction products of alpha-pinene, beta-pinene, sabinene, 3-carene and limonene with OH radicals and of alpha-pinene with ozone using FT-IR spectroscopy for measuring gas phase products and HPLC-MS-MS to measure products in the aerosol phase. These techniques were used to investigate the secondary organic aerosol (SOA) formation from the terpenes. The gas phase reaction products were all quantified using reference compounds. At low terpene concentrations (0.9-2.1 ppm), the molar yields of gas phase reaction products were: HCHO 16-92%, HCOOH 10-54% (OH source: H2O2, 6-25 ppm); HCHO 127-148%, HCOOH 4-6% (OH source: CH3ONO, 5-8 ppm). At high terpene concentrations (4.1-13.2 ppm) the results were: HCHO 9-27%, HCOOH 15-23%, CH3(CO)CH3 0-14%, CH3COOH 0-5%, nopinone 24% (only from beta-pinene oxidation), limona ketone 61% (only from limonene oxidation), pinonaldehyde was identified during alpha-pinene degradation (OH source H2O2, 23-30 ppm); HCHO 76-183%, HCOOH 12-15%, CH3(CO)CH3 0-12%, nopinone 17% (from beta-pinene oxidation), limona ketone 48% (from limonene oxidation), pinonaldehyde was identified during alpha-pinene degradation (OH source CH3ONO, 14-16 ppm). Pinic acid, pinonic acid, limonic acid, limoninic acid, 3-caric acid, 3-caronic acid and sabinic acid were identified in the aerosol phase. On the basis of these results, we propose a formation mechanism for pinonic and pinic acid in the aerosol phase explaining how degradation products could influence SOA formation and growth in the troposphere.

  8. Degradation of Corn Oil Wastes by Fenton Reaction and Under Mildly Basic Media in the Presence of Oxidants Assisted with Sun Light

    OpenAIRE

    Josefina V.  Sanchez; Susana S.  Martinez; Maria D.F.T.  Hernandez

    2008-01-01

    The degradation of water soluble corn oil wastes was carried out by Fenton reaction and also under mildly basic media in the presence of oxidants, such as hydrogen peroxide and persulfate, assisted with solar light. The degradation efficiency was obtained by analysis of chemical oxygen demand, carbon dioxide and gas chromatography. Over 90% of both chemical oxygen demand abatement and carbon dioxide recovery was accomplished by Fenton reaction. The presence of oxidants during the photodegrada...

  9. Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents.

    Science.gov (United States)

    Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

    2013-01-01

    The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal. PMID:23508150

  10. Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents.

    Science.gov (United States)

    Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

    2013-01-01

    The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

  11. Structural characterization of alkaline and oxidative stressed degradation products of lurasidone using LC/ESI/QTOF/MS/MS.

    Science.gov (United States)

    Talluri, M V N Kumar; Dharavath, Shireesha; Kalariya, Pradipbhai D; Prasanth, B; Srinivas, R

    2015-02-01

    A selective, accurate, precise and robust stability indicating liquid chromatography assay method was developed for the monitoring of a novel antipsychotic drug, lurasidone, in the presence of its degradation products (DPs). Also, we investigated degradation behavior of the drug under various stressed conditions such as hydrolytic (acidic, basic and neutral), oxidation, photolytic and thermal. The drug was found to be degraded under base hydrolytic and oxidative conditions, while it was stable in acid and neutral hydrolytic, photolytic and thermal conditions. The method showed adequate separation of lurasidone and its DPs on Xterra C18 (150 mm × 4.6 mm i.d., 3.5 μm) column using 20 mM ammonium formate (pH 3.0): acetonitrile as a mobile phase in gradient elution mode at a flow rate of 0.6 mL/min. This method was extended to liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI/QTOF/MS/MS) for structural characterization of DPs. A total of five DPs were characterized by LC/ESI/QTOF/MS/MS studies. Most probable mechanisms for the formation of DPs were proposed. The developed method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per International Conference on Harmonization Guideline Q2 (R1). PMID:25527975

  12. One-pot synthesis of ultrathin manganese dioxide nanosheets and their efficient oxidative degradation of Rhodamine B

    Science.gov (United States)

    Sun, Hang; Xu, Kongliang; Huang, Majia; Shang, Yinxing; She, Ping; Yin, Shengyan; Liu, Zhenning

    2015-12-01

    Ultrathin manganese dioxide (MnO2) nanosheets have been synthesized in aqueous solution by a facile one-step method. MnO2 nanosheets show a typical 2D lamellar morphology, possessing an average lateral dimension of 100-300 nm, and a typical thickness of 3.1-7.5 nm, corresponding to 4-10 layers of δ-MnO2. The resultant MnO2 nanosheets have been demonstrated to possess superior oxidative degradation ability to Rhodamine B (RhB) by investigating the decomposition rate and comparing the results with the commercial MnO2 powder. Typically, ultrathin MnO2 nanosheets have shown a high oxidation degradation performance of RhB solution (97.9% removed within 30 min) in acid solution (pH 2.0), which can be attributed to special lamellar morphology and the large surface area of the layered MnO2 nanosheets. It is believed that such a convenient approach for the cost-effective and environmentally friendly synthesis of ultrathin MnO2 nanosheets holds great promise for the degradation of complex and various dye wastewater in practical application.

  13. Assessment of the cathode contribution to the degradation of anode-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Hagen, Anke; Liu, Yi-Lin; Barfod, Rasmus;

    2008-01-01

    The degradation of anode-supported cells was studied over 1500 h as a function of cell polarization either in air or oxygen on the cathode side. Based on impedance analysis, contributions of the anode and cathode to the increase of total resistance were assigned. Accordingly, the degradation rate......-stabilized zirconia electrolyte and consequently a reduced three-phase boundary length. (C) 2008 The Electrochemical Society....

  14. Microbial degradation of high impact polystyrene (HIPS), an e-plastic with decabromodiphenyl oxide and antimony trioxide.

    Science.gov (United States)

    Sekhar, Vini C; Nampoothiri, K Madhavan; Mohan, Arya J; Nair, Nimisha R; Bhaskar, Thallada; Pandey, Ashok

    2016-11-15

    Accumulation of electronic waste has increased catastrophically and out of that various plastic resins constitute one of the leading thrown out materials in the electronic machinery. Enrichment medium, containing high impact polystyrene (HIPS) with decabromodiphenyl oxide and antimony trioxide as sole carbon source, was used to isolate microbial cultures. The viability of these cultures in the e-plastic containing mineral medium was further confirmed by triphenyl tetrazolium chloride (TTC) reduction test. Four cultures were identified by 16S rRNA sequencing as Enterobacter sp., Citrobacter sedlakii, Alcaligenes sp. and Brevundimonas diminuta. Biodegradation experiments were carried out in flask level and gelatin supplementation (0.1% w/v) along with HIPS had increased the degradation rate to a maximum of 12.4% (w/w) within 30days. This is the first report for this kind of material. The comparison of FTIR, NMR, and TGA analysis of original and degraded e-plastic films revealed structural changes under microbial treatment. Polystyrene degradation intermediates in the culture supernatant were also detected using HPLC analysis. The gravity of biodegradation was validated by morphological changes under scanning electron microscope. All isolates displayed depolymerase activity to substantiate enzymatic degradation of e-plastic.

  15. Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP mineralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min(1, 4-chlorophenol at concentration of 10 mg·L(1 could be completely degraded at the radiation dose of 2 kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min(1, which was 2.4 times higher than the sum of radiation (0.0294 min(1) and ozonation (0.0137 min(1). It revealed that the combination of radiation and ozonation resulted in synergistic effect, which can remarkably increase the degradation efficiency of 4-CP.

  16. Rare earth oxide-doped titania nanocomposites with enhanced photocatalytic activity towards the degradation of partially hydrolysis polyacrylamide

    Science.gov (United States)

    Li, Jinhuan; Yang, Xia; Yu, Xiaodan; Xu, Leilei; Kang, Wanli; Yan, Wenhua; Gao, Hongfeng; Liu, Zhonghe; Guo, Yihang

    2009-01-01

    Rare-earth oxide-doped titania nanocomposites (RE 3+/TiO 2, where RE = Eu 3+, Pr 3+, Gd 3+, Nd 3+, and Y 3+) were prepared by a one-step sol-gel-solvothermal method. The products exhibited anatase phase structure, mesoporosity, and interesting surface compositions with three oxygen species and two titanium species. The products were used as the photocatalysts to degrade a partially hydrolysis polyacrylamide (HPAM) under UV-light irradiation, a very useful polymer in oil recovery. For comparison, Degussa P25 and as-prepared pure TiO 2 were also tested under the same conditions. The enhanced photocatalytic activity was obtained on as-prepared Eu 3+ (Gd 3+, Pr 3+)/TiO 2 composites, and the reasons were explained. Finally, the degradation pathway of HPAM over the RE 3+/TiO 2 composite was put forward based on the intermediates produced during the photocatalysis procedure.

  17. Effect of oxidation on nitro-based pharmaceutical degradation and trichloronitromethane formation.

    Science.gov (United States)

    Wang, Xiaofeng; Zhou, Beihai; Yang, Hongwei; Wang, Xiaomao; Xie, Yuefeng

    2016-03-01

    Nitro-based compounds are the direct precursors of trichloronitromethane during chlorination disinfection. Two nitro-based pharmaceuticals ranitidine and nizatidine were selected as model compounds to assess the effect of oxidation on the removal of nitro-based pharmaceuticals, as well as the reduction of their trichloronitromethane formation potentials (TCNMFPs). The four oxidants were ozone (O3), chlorine (Cl2), chlorine dioxide (ClO2) and potassium permanganate (KMnO4). The changes in pharmaceuticals and their TCNMFPs during oxidation using various oxidants and dosages were quantified. The relationships between oxidation product structures and TCNMFP changes were also analyzed. The results showed that oxidation with Cl2 and KMnO4 were more effective than ClO2 and O3 in removing the nitro-based pharmaceuticals. Meanwhile, decreased TCNMFPs by KMnO4 oxidation but increased TCNMFPs by Cl2, ClO2 and O3 oxidation were observed. The results of product analysis indicated that chlorine transfer products had higher TCNMFPs, while oxygen transfer products made little contribution to TCNMFPs after oxidation. In addition, one possible reaction pathway leading TCNMFP increase was that chloro-nitromethane or nitromethane, which was a better TCNM precursor, formed when double bond was attacked by oxidants. PMID:26714298

  18. A novel hybrid nano zerovalent iron initiated oxidation--biological degradation approach for remediation of recalcitrant waste metalworking fluids.

    Science.gov (United States)

    Jagadevan, Sheeja; Jayamurthy, Manickam; Dobson, Peter; Thompson, Ian P

    2012-05-01

    Disposal of operationally exhausted metal working fluids (MWF) through a biological route is an attractive option, since it is effective with relatively low energy demands. However, it is enormously challenging since these fluids are chemically complex, including the addition of toxic biocides which are added specifically to retard bio-deterioration whilst the fluids are operational. Nano-sized elemental iron represents a new generation of environmental remediation technologies. Laboratory scale batch studies were performed to test the degradation ability of a semi-synthetic metalworking fluid (MWF) wastewater (which was found to be resistant to initial bacterial treatment in specifically established bioreactors) by employing a novel hybrid approach. The approach was to combine the synergistic effects of nano zerovalent iron (nZVI) induced oxidation, followed by biodegradation, specifically for the remediation of recalcitrant components of MWF effluent. Addition of nZVI particles to oxygenated wastewater resulted in oxidation of organic contaminants present. Our studies confirmed 78% reduction in chemical oxygen demand (COD) by nZVI oxidation at pH 3.0 and 67% reduction in neutral pH (7.5), and 85% concurrent reduction in toxicity. Importantly, this low toxicity made the nZVI treated effluent more amenable for a second stage biological oxidation step. An overall COD reduction of 95.5% was achieved by the novel combined treatment described, demonstrating that nZVI oxidation can be exploited for enhancing the biodegradability of a recalcitrant wastewater in treatment processes. PMID:22365368

  19. PEGylated single-walled carbon nanotubes activate neutrophils to increase production of hypochlorous acid, the oxidant capable of degrading nanotubes

    International Nuclear Information System (INIS)

    Perspectives for the use of carbon nanotubes in biomedical applications depend largely on their ability to degrade in the body into products that can be easily cleared out. Carboxylated single-walled carbon nanotubes (c-SWCNTs) were shown to be degraded by oxidants generated by peroxidases in the presence of hydrogen peroxide. In the present study we demonstrated that conjugation of poly(ethylene glycol) (PEG) to c-SWCNTs does not interfere with their degradation by peroxidase/H2O2 system or by hypochlorite. Comparison of different heme-containing proteins for their ability to degrade PEG-SWCNTs has led us to conclude that the myeloperoxidase (MPO) product hypochlorous acid (HOCl) is the major oxidant that may be responsible for biodegradation of PEG-SWCNTs in vivo. MPO is secreted mainly by neutrophils upon activation. We hypothesize that SWCNTs may enhance neutrophil activation and therefore stimulate their own biodegradation due to MPO-generated HOCl. PEG-SWCNTs at concentrations similar to those commonly used in in vivo studies were found to activate isolated human neutrophils to produce HOCl. Both PEG-SWCNTs and c-SWCNTs enhanced HOCl generation from isolated neutrophils upon serum-opsonized zymosan stimulation. Both types of nanotubes were also found to activate neutrophils in whole blood samples. Intraperitoneal injection of a low dose of PEG-SWCNTs into mice induced an increase in percentage of circulating neutrophils and activation of neutrophils and macrophages in the peritoneal cavity, suggesting the evolution of an inflammatory response. Activated neutrophils can produce high local concentrations of HOCl, thereby creating the conditions favorable for degradation of the nanotubes. -- Highlights: ► Myeloperoxidase (MPO) product hypochlorous acid is able to degrade CNTs. ► PEGylated SWCNTs stimulate isolated neutrophils to produce hypochlorous acid. ► SWCNTs are capable of activating neutrophils in blood samples. ► Activation of neutrophils in

  20. Kinetic Modeling for Microwave-Enhanced Degradation of Methylene Blue Using Manganese Oxide

    Directory of Open Access Journals (Sweden)

    Wen-Hui Kuan

    2013-01-01

    Full Text Available This study was originally performed to compare the MnO2-based degradation of aqueous methylene blue (MB under microwave irradiation- (MW- enhanced and conventional heating- (CH- enhanced conditions. The degradation process and kinetics were investigated to elucidate the microwave effect on the reaction. The results showed that all three tested conditions, sole MnO2, MnO2/CH, and MnO2/MW, followed the third-order (second upon MB and first upon MnO2 kinetic model. However, a higher degradation rate of MB was available under the MW-enhanced process, which implies that the “athermal effect” of MW might be of more benefit for the generation of electrophilic oxygen ions (, , and to degrade MB. The results showed that the degradation percentage of MB could reach 100%, corresponding to 92% total organic carbon (TOC removal under microwave irradiation at pH 7.20 for 10 min.

  1. Electrochemical degradation of polycyclic aromatic hydrocarbons in creosote solution using ruthenium oxide on titanium expanded mesh anode.

    Science.gov (United States)

    Tran, Lan-Huong; Drogui, Patrick; Mercier, Guy; Blais, Jean-François

    2009-05-30

    In this study, expanded titanium (Ti) covered with ruthenium oxide (RuO(2)) electrode was used to anodically oxidize polycyclic aromatic hydrocarbons (PAH) in creosote solution. Synthetic creosote-oily solution (COS) was prepared with distilled water and a commercial creosote solution in the presence of an amphoteric surfactant; Cocamidopropylhydroxysultaine (CAS). Electrolysis was carried out using a parallelepipedic electrolytic 1.5-L cell containing five anodes (Ti/RuO(2)) and five cathodes (stainless steel, 316 L) alternated in the electrode pack. The effects of initial pH, temperature, retention time, supporting electrolyte, current density and initial PAH concentration on the process performance were examined. Experimental results revealed that a current density of 9.23 mA cm(-2) was beneficial for PAH oxidation. The sum of PAH concentrations for 16 PAHs could be optimally diminished up to 80-82% while imposing a residence time in the electrolysis cell of 90 min. There was not a significant effect of the electrolyte (Na(2)SO(4)) concentration on oxidation efficiency in the investigated range of 500-4000 mg/L. However, an addition of 500 mg Na(2)SO(4)L(-1) was required to reduce the energy consumption and the treatment cost. Besides, there was no effect of initial PAH concentration on oxidation efficiency in the investigated range of 270-540 mg PAHL(-1). Alkaline media was not favourable for PAH oxidation, whereas high performance of PAH degradation could be recorded without initial pH adjustment (original pH around 6.0). Likewise, under optimal conditions, 84% of petroleum hydrocarbon (C(10)-C(50)) was removed, whereas removal yields of 69% and 62% have been measured for O&G and COD, respectively. Microtox and Daphnia biotests showed that electrochemical oxidation using Ti/RuO(2) could be efficiently used to reduce more than 90% of the COS toxicity. PMID:18926633

  2. Degradation and decoloration of contaminated water with textile dyes using advanced oxidation processes

    Directory of Open Access Journals (Sweden)

    Laura Castro-Peña

    2014-05-01

    Full Text Available The degradation and decolorization of azo dye COLRON RED SD3B as model pollutant by H2O2/ UV and H2O2/Fe2+/UV processes were investigated. The effects of dye concentration, solution pH, and Fe2+ and H2O2 dosages were studied using Taguchi´s experimental design method. Photo-Fenton process showed to be more efficient than H2O2/UV process for the color removal and degradation of the dye. The conditions that produced higher degradations rates were pH=2, dye concentration of 100 ppm, ferrous dosage of 80 ppm and hydrogen peroxide dosage of 102 ppm (3.0 mmol/L. Under these conditions, 65.5 % COD reduction and 77.0 % decolorization of the azo dye wastewater were achieved after one hour of treatment.

  3. An Overview: Recent Development of Titanium Oxide Nanotubes as Photocatalyst for Dye Degradation

    Directory of Open Access Journals (Sweden)

    Chin Wei Lai

    2014-01-01

    Full Text Available Today, organic dyes are one of the largest groups of pollutants release into environment especially from textile industry. It is highly toxic and hazardous to the living organism; thus, the removal of these dyes prior to discharge into the environment is essential. Varieties of techniques have been employed to degrade organic dyes and heterogeneous photocatalysis involving titanium dioxide (TiO2 appears to be the most promising technology. In recent years, TiO2 nanotubes have attracted much attention due to their high surface area and extraordinary characteristics. This paper presents a critical review of recent achievements in the modification of TiO2 nanotubes for dye degradation. The photocatalytic activity on dye degradation can be further enhanced by doping with cationic or anionic dopant.

  4. Oxidative Degradation of o-Chlorophenol with Contact Glow Discharges in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    高锦章; 杨武; 刘永军; 陈平; 纳鹏君; 陆泉芳

    2003-01-01

    Contact glow discharge electrolysis (CGDE) of o-chlorophenol (2-CP) was investi-gated under different pH, voltages and initial concentrations. And the mechanism of the oxidationwas explored. The results suggested that the degradation followed the first order kinetic law;Fe2+ had a remarkable catalytic effect on the removal rate of o-chloropenol. In the presence ofFe2+, 2-CP underwent an exhaustive degradation, from which the major intermediates includedo-dihydroxybenze, p-hydroxybenze, p-benzoquione and carboxlic acids.

  5. Ultrasonic-assisted degradation of phenazopyridine with a combination of Sm-doped ZnO nanoparticles and inorganic oxidants.

    Science.gov (United States)

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi

    2016-01-01

    Pure and samarium doped ZnO nanoparticles were synthesized by a sonochemical method and characterized by TEM, SEM, EDX, XRD, Pl, and DRS techniques. The average crystallite size of pure and Sm-doped ZnO nanoparticles was about 20 nm. The sonocatalytic activity of pure and Sm-doped ZnO nanoparticles was considered toward degradation of phenazopyridine as a model organic contaminant. The Sm-doped ZnO nanoparticles with Sm concentration of 0.4 mol% indicated a higher sonocatalytic activity (59%) than the pure ZnO (51%) and other Sm-doped ZnO nanoparticles. It was believed that Sm(3+) ion with optimal concentration (0.4 mol%) can act as superficial trapping for electrons in the conduction band of ZnO and delayed the recombination of charge carriers. The influence of the nature and concentration of various oxidants, including periodate, hydrogen peroxide, peroxymonosulfate, and peroxydisulfate on the sonocatalytic activity of Sm-doped ZnO nanoparticles was studied. The influence of the oxidants concentration (0.2-1.4 g L(-1)) on the degradation rate was established by the 3D response surface and the 2D contour plots. The results demonstrated that the utilizing of oxidants in combination with Sm-doped ZnO resulting in rapid removal of contaminant, which can be referable to a dual role of oxidants; (i) scavenging the generated electrons in the conduction band of ZnO and (ii) creating highly reactive radical species under ultrasonic irradiation. It was found that the Sm-doped ZnO and periodate combination is the most efficient catalytic system under ultrasonic irradiation. PMID:26384896

  6. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    International Nuclear Information System (INIS)

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO4·−) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe3O4/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe3O4/Cu1.5Ni0.5Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe3O4/Cu(Ni)Cr-LDH to generate sulfate radicals (SO4·−). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO4·−), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe3O4/Cu(Ni)Cr-LDH composite could be applied widely for the treatment of organic dyes in wastewater

  7. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dan; Ma, Xiaolong; Zhou, Jizhi [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China); Chen, Xi [Department of Earth and Environmental Engineering, Columbia University, West 120th Street, New York, NY 10027 (United States); Qian, Guangren, E-mail: grqian@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China)

    2014-08-30

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO{sub 4}·{sup −}) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe{sub 3}O{sub 4}/Cu{sub 1.5}Ni{sub 0.5}Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH to generate sulfate radicals (SO{sub 4}·{sup −}). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO{sub 4}·{sup −}), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe{sub 3}O{sub 4

  8. Interactive Oxidation of Photocatalysis and Electrocatalysis for Degradation of Phenol in a Photoreactor

    Institute of Scientific and Technical Information of China (English)

    樊彩梅; 王艳; 梁镇海; 王韵芳; 郝晓刚; 孙彦平

    2009-01-01

    TiO2/C particles as photocatalyst were prepared by dipping TiO2 suspension solution with activated carbon and were applied in the photocatalytic-electrocatalytic degradation of phenol,the Ti/SnO2+Sb2O3/PbO2 electrode and oxygen diffusion electrode were used as anode and cathode respectively,and a 250 W ultraviolet lamp (365 nm) as side light source.The SEM results of TiO2/C and Ti/SnO2+Sb2O3/PbO2 anode indicated that the TiO2 on carbon particles was uniform and PbO2 film on the surface of anode was in cauliflower form,the XRD result of oxygen diffusion electrode showed that only crystalline graphite was found.The influential parameters of degradation process such as applied cell voltage (E),initial concentration of phenol (C0),amount of TiO2 catalyst and air flow rate (v) were discussed.Under the following experimental conditions of C0=50 mg/L,pH=6,E=2 V,TiO2 0.98 mg/mL,v=382.2 mL/min,and light intensity I=10.5 mW/cm2,phenol could be entirely degraded,and about 89% of total organic carbon (TOC) was removed after 3 h degradation.

  9. Characterization of degradation products from alkaline wet oxidation of wheat straw

    DEFF Research Database (Denmark)

    Klinke, H.B.; Ahring, B.K.; Schmidt, A.S.;

    2002-01-01

    constituted the majority of degradation products (8.5 g). The main phenol monomers were 4-hydroxybenzaldehyde, vanillin, syringaldehyde, acetosyringone (4-hydroxy-3,5-dimethoxy-acetophenone), vanillic acid and syringic acid, occurring in 0.04-0.12 g per 100 g straw concentrations. High lignin removal from...

  10. Understanding degradation of solid oxide electrolysis cells through modeling of electrochemical potential profiles

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Chen, Ming; Hendriksen, Peter Vang;

    2016-01-01

    Establishing the spatial distribution of the various chemical and electrochemical potentials in an operating SOEC is critical as several degradation mechanisms are tightly connected to them, but at the same time very challenging to achieve experimentally. Such distributions are presented here on ...

  11. Degradation of quinoline by wet oxidation - kinetic aspects and reaction mechanisms

    DEFF Research Database (Denmark)

    Thomsen, A.B.

    1998-01-01

    of succinic acid is suggested to be a result of a coupling reaction of the acetic acid radical A reaction mechanism is suggested for the degradation of quinoline: it involves hydroxyl radicals and the possible interaction with autoclave walls is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved....

  12. Effect of oxidation on amine-based pharmaceutical degradation and N-Nitrosodimethylamine formation.

    Science.gov (United States)

    Wang, Xiaofeng; Yang, Hongwei; Zhou, Beihai; Wang, Xiaomao; Xie, Yuefeng

    2015-12-15

    Four pharmaceuticals (ranitidine, nizatidine, doxylamine, and carbinoxamine) were selected as model compounds to assess the efficiency of four oxidants (ozone (O3), chlorine (Cl2), chlorine dioxide (ClO2) and potassium permanganate (KMnO4)) on the removal of amine-based pharmaceutical and personal care products (PPCPs), as well as the reduction of their N-Nitrosodimethylamine formation potentials (NDMAFPs). The changes in PPCPs and their NDMAFPs during oxidation were quantified using various oxidants and dosages. The relationship between oxidation product structures and NDMAFP changes was also analyzed. The results showed that oxidation with O3, Cl2 and ClO2 were effective in removing the selected PPCPs. However, only ozonation was effective in reducing their NDMAFPs. Ozonation at 6 mg/L removed approximately 90% PPCPs and 90% NDMAFPs for all PPCPs. In addition, the results indicated that ozonation products made little contribution to NDMAFPs. In contrast, some PPCP products had higher NDMAFPs than PPCPs after oxidation with Cl2, ClO2 and KMnO4. There were two possible reaction pathways that led to decrease in NDMAFPs after oxidation. One was oxygen transfer to nitrogen at the tertiary amine site and the other was N-dealkylation from the tertiary amine site. PMID:26469132

  13. Solid Oxide Electrolysis Cells: Microstructure and Degradation of the Ni/Yttria-Stabilized Zirconia Electrode

    DEFF Research Database (Denmark)

    Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard;

    2008-01-01

    Solid oxide fuel cells produced at Risø DTU have been tested as solid oxide electrolysis cells for steam electrolysis by applying an external voltage. Varying the sealing on the hydrogen electrode side of the setup verifies that the previously reported passivation over the first few hundred hours...... of tested solid oxide electrolysis cells. Electrolysis testing at high current density, high temperature, and a high partial pressure of steam [−2 A/cm2, 950°C, p(H2O)=0.9 atm] was observed to lead to significant microstructural changes at the hydrogen electrode-electrolyte interface....

  14. Mechanism and kinetic properties of OH-initiated atmospheric oxidation degradation of methamidophos in the presence of O2/NO

    Science.gov (United States)

    Shi, Xiangli; Zhang, Ruiming; Zhang, Qingzhu; Wang, Wenxing

    2016-05-01

    Methamidophos is a member of the organophosphorus insecticides. In the present work, the mechanism of the OH radical-initiated atmospheric oxidation degradation of methamidophos and the possible degradation products were investigated with the aid of quantum chemical calculations. The geometrical parameters and vibrational frequencies were calculated at the MPWB1K/6-31+G(d,p) level. The energies of all the stationary points were carried out at the MPWB1K/6-311+G(3df,2p) level of theory. The rate constants of key elementary steps involved in the OH radical-initiated atmospheric degradation of methamidophos were calculated by meaning of the canonical variation transition-state (CVT) theory with the small curvature tunneling (SCT) correction over the possible atmospheric temperature range of 273-333 K. The rate-temperature formulas were fitted for the first time. The pre-exponential factor and the activation energy were obtained. Studies show that the OH additions from the trans-positions of the NH2 and OCH3 groups, the H abstractions from the SCH3 and OCH3 groups as well as the substitution reaction resulting in the products of CH3OP(O)OHNH2 and SCH3 are thermodynamically favorable reaction pathways for the reaction of methamidophos with OH radicals due to the low barrier and strong exothermicity.

  15. Hydrothermal synthesis of fluorinated anatase TiO2/reduced graphene oxide nanocomposites and their photocatalytic degradation of bisphenol A

    Science.gov (United States)

    Luo, Lijun; Yang, Ye; Zhang, Ali; Wang, Min; Liu, Yongjun; Bian, Longchun; Jiang, Fengzhi; Pan, Xuejun

    2015-10-01

    The surface fluorinated TiO2/reduced graphene oxide nanocomposites (denoted as F-TiO2-RGO) were synthesized via hydrothermal method. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectroscopy, Fourier Transform Infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The results showed that pure anatase TiO2 particles were anchored on the surface of reduced graphene oxide. And the HF added during the preparation process can not only prevent phase transformation from anatase to rutile, but also the F- ion adsorbed on the surface of TiO2-RGO surface can enhance photocatalytic activity of F-TiO2-RGO. The photocatalytic activities of F-TiO2-RGO nanocomposites were evaluated by decomposing bisphenol A under UV light illumination. Under optimal degradation condition, the degradation rate constant of BPA over F-TiO2-10RGO (0.01501 min-1) was 3.41 times than that over P25 (0.00440 min-1). The result indicated that the enhanced photocatalytic activity of F-TiO2-10RGO was ascribed to the adsorbed F ion and RGO in F-TiO2-RGO composite, which can reduce the recombination rate of the photo-generated electrons and holes synergistically.

  16. Radiation synthesis of CdS/reduced graphene oxide nanocomposites for visible-light-driven photocatalytic degradation of organic contaminant

    Science.gov (United States)

    Fu, Xiaoyang; Zhang, Youwei; Cao, Pengfei; Ma, Huiling; Liu, Pinggui; He, Lihua; Peng, Jing; Li, Jiuqiang; Zhai, Maolin

    2016-06-01

    CdS/reduced graphene oxide (CdS/RGO) nanocomposites were successfully synthesized via a one-step gamma-ray radiation-induced reduction method. The composition and structure of the prepared nanocomposites were characterized by thermal gravimetric analysis, micro FTIR spectroscopy, UV-vis spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. It was found that increasing dose could improve the degree of reduction of graphite oxide (GO), and the feed ratio of GO to CdCl2·2.5H2O significantly influenced the size and dispersion of the CdS nanoparticles. The nanocomposites prepared under dose of 300 kGy and the feed ratio of GO to CdCl2·2.5H2O 1.0 wt% exhibited high visible-light photocatalytic performance for the degradation of Rhodamine B with degradation efficiency of 93%. This work provides a novel and facile method to produce the nanocomposites as efficient photocatalysts for the removal of organic contaminants from aqueous solution.

  17. A kinetic model of municipal sludge degradation during non-catalytic wet oxidation.

    Science.gov (United States)

    Prince-Pike, Arrian; Wilson, David I; Baroutian, Saeid; Andrews, John; Gapes, Daniel J

    2015-12-15

    Wet oxidation is a successful process for the treatment of municipal sludge. In addition, the resulting effluent from wet oxidation is a useful carbon source for subsequent biological nutrient removal processes in wastewater treatment. Owing to limitations with current kinetic models, this study produced a kinetic model which predicts the concentrations of key intermediate components during wet oxidation. The model was regressed from lab-scale experiments and then subsequently validated using data from a wet oxidation pilot plant. The model was shown to be accurate in predicting the concentrations of each component, and produced good results when applied to a plant 500 times larger in size. A statistical study was undertaken to investigate the validity of the regressed model parameters. Finally the usefulness of the model was demonstrated by suggesting optimum operating conditions such that volatile fatty acids were maximised. PMID:26426294

  18. Anodic oxidation of oxytetracycline: Influence of the experimental conditions on the degradation rate and mechanism

    Directory of Open Access Journals (Sweden)

    Annabel Fernandes

    2014-12-01

    Full Text Available The anodic oxidation of oxytetracycline was performed with success using as anode a boron-doped diamond electrode. The experiments were conducted in batch mode, using two different electrochemical cells: an up-flow cell, with recirculation, that was used to evaluate the influence of recirculation flow rate; and a stirred cell, used to determine the influence of the applied current density. Besides oxytetracyclin electrodegradation rate and mineralization extent, oxidation by-products were also assessed. Both the flow rate and the applied current density have shown positive influence on the oxytetracycline oxidation rate. On the other hand, the mineralization degree presented the highest values at the lowest flow rate and the lowest current density tested. The main oxidation by-products detected were oxalic, oxamic and maleic acids.

  19. Anodic oxidation of oxytetracycline: Influence of the experimental conditions on the degradation rate and mechanism

    OpenAIRE

    Annabel Fernandes; Catarina Oliveira; MARIA J PACHECO; Lurdes Ciríaco; Ana Lopes

    2014-01-01

    The anodic oxidation of oxytetracycline was performed with success using as anode a boron-doped diamond electrode. The experiments were conducted in batch mode, using two different electrochemical cells: an up-flow cell, with recirculation, that was used to evaluate the influence of recirculation flow rate; and a stirred cell, used to determine the influence of the applied current density. Besides oxytetracyclin electrodegradation rate and mineralization extent, oxidation by-products were als...

  20. Application of Silver and Silver Oxide Nanoparticles Impregnated on Activated Carbon to the Degradation of Bromate.

    Science.gov (United States)

    Choi, J S; Lee, H; Park, Y K; Kim, S J; Kim, B J; An, K H; Kim, B H; Jung, S C

    2016-05-01

    Silver and silver oxide nanoparticles were impregnated on the surface of powdered activated carbon (PAC) using a single-step liquid phase plasma (LPP) method. Spherical silver and silver oxide nanoparticles of 20 to 100 nm size were dipersed evenly on the surface of PAC. The impregnated PAC exhibited a higher activity for the decomposition of bromate than bare PAC. The XPS, Raman and EDX analyses showed that the Ag/PAC composites synthesized by the LPP process. PMID:27483780

  1. C.I. Reactive Black 5 degradation by advanced electrochemical oxidation process, AEOP

    OpenAIRE

    Esteves, M. de Fátima; Sousa, Elisabete,1954-

    2007-01-01

    In the last decades, an increasing number of procedures to remove pollutants from wastewater have been reported. Advanced oxidation processes (AOPs) are one of those technologies used for this purpose, namely, for textile wastewater treatment. AOPs are environmentally friendly methods based on chemical, photochemical or photocatalytical production of hydroxyl radical (HO•). This strong oxidant can react with most organic compounds present in wastewater, as dyestuffs. In this paper, an Advance...

  2. Modelling TCE degradation by a mixed culture of methane-oxidizing bacteria

    DEFF Research Database (Denmark)

    Broholm, Kim; Christensen, Thomas Højlund; Jensen, Bjørn K.

    1992-01-01

    A model describing the growth of bacteria and the degradation of methane and trichloroethylene (TCE) based on the concept of competitive inhibition is proposed. The model has been applied to laboratory batch experiments representing different initial TCE concentrations (50–4300 μg/l) and initial...... methane concentrations (0.53–3.2 mg/l). The proposed model simulated successfully the data obtained for initial methane concentration (less than 1.8 mg/l), causing constant experimental growth conditions during the experiments. This indicates that the interactions between methane and TCE degradation can...... be explained as competitive inhibition. The model simulations of the results from the experiments with the highest initial methane concentration of 3.2 mg/l failed, supposedly because the growth conditions changed during the experiments. The proposed model is a useful engineering tool for design of treatment...

  3. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    DEFF Research Database (Denmark)

    Thydén, Karl Tor Sune

    2008-01-01

    are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work......, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused......-reforming catalysis. In the context of electrochemically tested and technologically relevant cells, the majority of the microstructural work is performed on a cell tested at 850°C under relatively severe conditions for 17,500 hours. It is demonstrated that the major Ni rearrangements take place at the interface...

  4. Photocatalytic Degradation of p-Cresol by Zinc Oxide under UV Irradiation

    Directory of Open Access Journals (Sweden)

    Nor Azah Yusof

    2011-12-01

    Full Text Available Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC. The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6–9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.

  5. Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

    OpenAIRE

    Ali Nickheslat; Mohammad Mehdi Amin; Hassan Izanloo; Ali Fatehizadeh; Seyed Mohammad Mousavi

    2013-01-01

    Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The ef...

  6. A study on the degradation of endocrine disruptors and dioxins by ozonation and advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, S.; Kenmochi, Y.; Tutumi, K.; Tanaka, T. [Ebara Corp., Fujisawa (Japan)

    2003-07-01

    Recently, enhancement and development of treatment technologies related to contaminated water environment by endocrine disruptors such as bisphenol-A(BPA), estradiol(E2) and dioxins have become a focus of attention. In this study, the influence of O{sub 3} dosage and the forms of endocrine disruptors on the degradability during O{sub 3} treatment and AOP treatment were investigated. A reaction kinetic evaluation of these processes was also carried out. In this study, the endocrine disruptors were classified into 2 groups: (1) DXNs: dioxins and (2) EDs: endocrine disruptors other than dioxins. For the case of DXNs decomposition, highly concentrated DXNs from incinerator washwater were degraded by UV/O{sub 3} combined treatment. Influence of O{sub 3} dosage and forms of DXNs on the reaction rate constant were evaluated. For the case of EDs decomposition, the effect of O{sub 3} dosage on the reaction rate constant were investigated during O{sub 3} treatment of secondary treated sewage. Also, a degradability comparison was made for the above 2 groups. (orig.)

  7. Kinetics of acetaminophen degradation by Fenton oxidation in a fluidized-bed reactor.

    Science.gov (United States)

    de Luna, Mark Daniel G; Briones, Rowena M; Su, Chia-Chi; Lu, Ming-Chun

    2013-01-01

    Acetaminophen (ACT), an analgesic and antipyretic substance, is one of the most commonly detected pharmaceutical compound in surface waters and wastewaters. In this study, fluidized-bed Fenton (FB-Fenton) was used to decompose ACT into its final degradation products. The 1.45-L cylindrical glass reactor had inlet, outlet and recirculating sections. SiO(2) carrier particles were supported by glass beads with 2-4 mm in diameter. ACT concentration was determined by high performance liquid chromatography (HPLC). During the first 40 min of reaction, a fast initial ACT removal was observed and the "two-stage" ACT degradation conformed to a pseudo reaction kinetics. The effects of ferrous ion dosage and [Fe(2+)]/[H(2)O(2)] (FH ratio) were integrated into the derived pseudo second-order kinetic model. A reaction pathway was proposed based on the intermediates detected through SPME/GC-MS. The aromatic intermediates identified were hydroquinone, benzaldehydes and benzoic acids while the non-aromatic substances include alcohols, ketones, aldehydes and carboxylic acids. Rapid initial ACT degradation rate can be accomplished by high initial ferrous ion concentration and/or low FH ratio.

  8. Oxidative degradation of salicylic acid by sprayed WO{sub 3} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Mohite, S.V.; Rajpure, K.Y., E-mail: rajpure@yahoo.com

    2015-10-15

    Highlights: • The photoactivity of sprayed WO{sub 3} thin film. • Photoelectrocatalytic degradation of salicylic acid. • Reaction kinetics and mineralization of pollutants by COD. - Abstract: The WO{sub 3} thin films were deposited using spray pyrolysis technique. The prepared WO{sub 3} thin films were characterized using photoelectrochemical (PEC), X-ray diffraction, atomic force microscopy (AFM), and UV–vis absorbance spectroscopy techniques. PEC measurements of WO{sub 3} films deposited at different deposition temperatures were carried out to study photoresponse. The maximum photocurrent (I{sub ph} = 261 μA/cm{sup 2}) was observed for the film deposited at the 225 °C. The monoclinic crystal structure of WO{sub 3} has been confirmed from X-ray diffraction studies. AFM studies were used to calculate particle size and average roughness of the films. Optical absorbance was studied to estimate the bandgap energy of WO{sub 3} thin film which was about 2.65 eV. The photoelectrocatalytic activity of WO{sub 3} film was studied by degradation of salicylic acid with reducing concentrations as function of reaction time. The WO{sub 3} photocatalyst degraded salicylic acid to about 67.14% with significant reduction in chemical oxygen demand (COD) value.

  9. Involvement of Hydrogen Peroxide Generated by Polyamine Oxidative Degradation in the Development of Lateral Roots in Soybean

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to determine whether hydrogen peroxide (H2O2) generated by polyamine oxidative degradation is involved in the development of lateral roots in soybean, the length and the number of lateral roots, the activities of polyamine oxidases and diamine oxidases, and the endogenous free polyamine and H2O2 content were analyzed in soybean (Glycine max (Linn.) Merr.) main roots of 2-d-old seedlings after treatments for 2 d with exogenous β-hydroxyethylhydrazine (an inhibitor of polyamine oxidases), H2O2, putrescine, cyclohexylamine (an inhibitor of spermidine synthase) or N,N'-dimethylthiourea (a scavenger of hydrogen peroxide).β-hydroxyethylhydrazine treatment strongly inhibited the development of lateral roots in soybean seedlings,reduced the activities of polyamine oxidases and diamine oxidases, decreased H2O2 levels, and led to the accumulation of endogenous polyamines in the main roots. The inhibitory effect of β-hydroxyethylhydrazine on root development could be alleviated by exogenously applied 10 μmol/L H2O2 (a major product of polyamine oxidation). Treatment with cyclohexylamine and putrescine promoted root growth slightly, but treatment with cyclohexylamine plus N,N'-dimethylthiourea or putrescine plus N,N'-dimethylthiourea prevented the development of soybean lateral roots. The effects of these treatments on the development of soybean lateral roots were consistent with the changes in endogenous H2O2 levels. These results suggest that the development of soybean lateral roots is associated with the oxidative degradation of polyamines, and that their products,especially H2O2, are likely to play an important role in the growth of soybean lateral roots.

  10. Study of degradation intermediates formed during electrochemical oxidation of pesticide residue 2,6-dichlorobenzamide (BAM) at boron doped diamond (BDD) and platinum-iridium anodes.

    Science.gov (United States)

    Madsen, Henrik Tækker; Søgaard, Erik Gydesen; Muff, Jens

    2014-08-01

    Electrochemical oxidation is a promising technique for degradation of otherwise recalcitrant organic micropollutants in waters. In this study, the applicability of electrochemical oxidation was investigated concerning the degradation of the groundwater pollutant 2,6-dichlorobenzamide (BAM) through the electrochemical oxygen transfer process with two anode materials: Ti/Pt90-Ir10 and boron doped diamond (Si/BDD). Besides the efficiency of the degradation of the main pollutant, it is also of outmost importance to control the formation and fate of stable degradation intermediates. These were investigated quantitatively with HPLC-MS and TOC measurements and qualitatively with a combined HPLC-UV and HPLC-MS protocol. 2,6-Dichlorobenzamide was found to be degraded most efficiently by the BDD cell, which also resulted in significantly lower amounts of intermediates formed during the process. The anodic degradation pathway was found to occur via substitution of hydroxyl groups until ring cleavage leading to carboxylic acids. For the BDD cell, there was a parallel cathodic degradation pathway that occurred via dechlorination. The combination of TOC with the combined HPLC-UV/MS was found to be a powerful method for determining the amount and nature of degradation intermediates. PMID:24873711

  11. Photocatalytic degradation of polycyclic aromatic hydrocarbons on soil surfaces using TiO2 under UV light

    International Nuclear Information System (INIS)

    The photocatalytic degradation of phenanthrene (PHE), pyrene (PYRE) and benzo[a]pyrene (BaP) on soil surfaces in the presence of TiO2 using ultraviolet (UV) light source was investigated in a photo chamber, in which the temperature was maintained 30 deg. C. The effects of various factors, namely TiO2, soil pH, humic acid, and UV wavelength, on the degradation performance of polycyclic aromatic hydrocarbons (PAHs) were studied. The results show that photocatalytic degradation of PAHs follows the pseudo-first-order kinetics. Catalyst TiO2 accelerated the photodegradation of PHE, PYRE and BaP significantly, with their half-lives being reduced from 533.15 to 130.77 h, 630.09 to 192.53 h and 363.22 to 103.26 h, respectively, when the TiO2 content was 0.5%. In acidic or alkaline conditions, the photocatalytic degradation rates of the PAHs were greater than those in neutral conditions. Humic acid significantly enhanced the PAH photocatalytic degradation by sensitizing radicals capable of oxidizing PAHs. Photocatalytic degradation rates of PYRE and BaP on soil surfaces with 2% TiO2 were different at UV irradiation wavelengths of 254, 310 and 365 nm, respectively. The synergistic effect of UV irradiation and TiO2 catalysis was efficient for degradation of PAHs in contaminated soil

  12. Stress degradation study and structure characterization of oxidation degradation product of dexlansoprazole using liquid chromatography-mass spectrometry/time of flight, liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance

    Institute of Scientific and Technical Information of China (English)

    Lakkireddy PRAKASH; M HIMAJA

    2016-01-01

    The present study deals with the forced degradation behavior of dexlansoprazole under International Conference on Harmonisation( ICH)prescribed stress conditions. The drug was found to be more labile under acid,base,neutral,oxidative hydrolysis and thermal stress,while it was moderately stable under photolytic conditions. The known and unknown degradation products were separated on a C-18 column using a stability-indicating method. Liquid chromatography-mass spectrometry( LC-MS)analysis was performed for all the deg-radation studies. Isolation and structure characterization of oxidation degradation products were executed using sophisticated tools,viz. preparative high performance liquid chromatography( HPLC),liquid chromatography-mass spectrometry/time of flight( LC-MS/TOF),liquid chromatography-tandem mass spectrometry( LC-MS/MS),and nuclear magnetic resonance( NMR). This study demonstrates an ample methodology of degradation studies and structure elucidation of unknown degradation products of dexlansoprazole,which helps in the development and stability study of active pharmaceutical ingredients and formulated products.

  13. Kinetic modeling of the oxidative degradation of additive free PE in bleach disinfected water

    Science.gov (United States)

    Mikdam, Aïcha; Colin, Xavier; Billon, Noëlle; Minard, Gaëlle

    2016-05-01

    The chemical interactions between PE and bleach were studied at 60°C in immersion in bleach solutions kept at a free chlorine concentration of 100 ppm and a pH of 5 or 7.2. It was found that the polymer undergoes a severe oxidation from the earliest weeks of exposure, in a superficial layer whose thickness (of about 50-70 µm) is almost independent of the pH value, although the superficial oxidation rate is faster in acidic than in neutral medium. Oxidation leads to the formation and accumulation of a large variety of carbonyl products (mostly ketones and carboxylic acids) and, after a few weeks, to a decrease in the average molar mass due to the large predominance of chain scissions over crosslinking. A scenario was elaborated for explaining such unexpected results. According to this scenario, the non-ionic molecules (Cl2 and ClOH) formed from the disinfectant in the water phase, would migrate deeply into PE and dissociate into highly reactive radicals (Cl• and HO•) in order to initiate a radical chain oxidation. A kinetic model was derived from this scenario for predicting the general trends of the oxidation kinetics and its dependence on environmental factors such as temperature, free chlorine concentration and pH. The validity of this model was successfully checked by comparing the numerical simulations with experimental data.

  14. Effect of Reverse Substrate Bias on Degradation of Ultra-Thin Gate-Oxide n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors under Different Stress Modes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yao; XU Ming-Zhen; TAN Chang-Hua

    2005-01-01

    @@ Degradation of ultra-thin gate-oxide n-channel metal-oxide-semiconductor field-effect transistors with the halo structure has been studied under different stress modes with a reverse substrate bias. The device degradation under the same stress mode with different reverse substrate voltages has been characterized by monitoring the substrate current in a stressing process, which follows a simple power law. When the gate voltage is less than the critical value, the device degradation will first decrease and then increase with the increasing reverse sub strate voltage, otherwise, the device degradation will increase continuously. The critical value can be obtained by measuring the substrate current variation with the increases of reverse substrate voltage and gate voltage. The experimental results indicate that the stress mode with enhanced injection efficiency and smaller device degradation can be obtained when the gate voltage is less than the critical value with a proper reverse substratevoltage chosen.

  15. EFFECTS OF ORGANIC COLORANTS ON PHOTO-INITIATED CROSSLINKING AND PHOTO-OXIDATION DEGRADATION OF POLYETHYLENE AND RELATED MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Guo-bing Zhang; Qiang-hua Wu; Bao-jun Qu

    2008-01-01

    The effects of three organic colorants on photo-initiated crosslinking and photo-oxidation degradation of polyethylene (PE) samples irradiated by microwave excited (MWE) UV lamp in the melt and the related mechanism have been studied by gel content and thermal extension rate determinations, X-ray photoelectron spectroscopy (XPS), mechanical property tests, UV spectroscopy, and light microscope. The data from the gel content and thermal extension rate determinations of photo-crosslinked polyethylene (XLPE) samples show that the three colorants can decrease the efficiency of photo-initiated crosslinking of polyethylene to some different degree, in which the effect of red colorant is the largest among the three colorants. The colorized samples of 1 mm thickness are easily to be crosslinked to a satisfactory gel content of about 70% by the MWE lamp and optimized reaction conditions, such as the concentration of colorant, irradiation time,and so on. The XPS results give the evidence that the colorants can accelerate the surface photo-oxidation during the photo-crosslinking of polyethylene. The photo-oxidation products such as -CH2-O-and-C(C=O)-groups on the surface of XLPE samples with the colorants apparently increase with increasing the irradiation time. The data from the mechanical tests show that the colorants reduce the tensile strength and improve the elongation at break of XLPE samples. All the above results show that the effects of the three colorants on photo-initiated crosslinking and photo-oxidative degradation decrease with the order of red > blue > green colorants. The light microscope photos show that the colorant can disperse well in PE resin. The mechanism of the colorant effects can be elucidated by comparison of the UV absorption spectra of photo-initiator and colorants. This is because the colorants absorb the same UV wavelength regions as photo-initiator, and thus decrease the photo-crosslinking efficiency of photo-initiator and accelerate the

  16. Advanced Chemical Reduction of Reduced Graphene Oxide and Its Photocatalytic Activity in Degrading Reactive Black 5

    Directory of Open Access Journals (Sweden)

    Christelle Pau Ping Wong

    2015-10-01

    Full Text Available Textile industries consume large volumes of water for dye processing, leading to undesirable toxic dyes in water bodies. Dyestuffs are harmful to human health and aquatic life, and such illnesses as cholera, dysentery, hepatitis A, and hinder the photosynthetic activity of aquatic plants. To overcome this environmental problem, the advanced oxidation process is a promising technique to mineralize a wide range of dyes in water systems. In this work, reduced graphene oxide (rGO was prepared via an advanced chemical reduction route, and its photocatalytic activity was tested by photodegrading Reactive Black 5 (RB5 dye in aqueous solution. rGO was synthesized by dispersing the graphite oxide into the water to form a graphene oxide (GO solution followed by the addition of hydrazine. Graphite oxide was prepared using a modified Hummers’ method by using potassium permanganate and concentrated sulphuric acid. The resulted rGO nanoparticles were characterized using ultraviolet-visible spectrophotometry (UV-Vis, X-ray powder diffraction (XRD, Raman, and Scanning Electron Microscopy (SEM to further investigate their chemical properties. A characteristic peak of rGO-48 h (275 cm−1 was observed in the UV spectrum. Further, the appearance of a broad peak (002, centred at 2θ = 24.1°, in XRD showing that graphene oxide was reduced to rGO. Based on our results, it was found that the resulted rGO-48 h nanoparticles achieved 49% photodecolorization of RB5 under UV irradiation at pH 3 in 60 min. This was attributed to the high and efficient electron transport behaviors of rGO between aromatic regions of rGO and RB5 molecules.

  17. A distributed real-time model of degradation in a solid oxide fuel cell, part II: Analysis of fuel cell performance and potential failures

    Science.gov (United States)

    Zaccaria, V.; Tucker, D.; Traverso, A.

    2016-09-01

    Solid oxide fuel cells are characterized by very high efficiency, low emissions level, and large fuel flexibility. Unfortunately, their elevated costs and relatively short lifetimes reduce the economic feasibility of these technologies at the present time. Several mechanisms contribute to degrade fuel cell performance during time, and the study of these degradation modes and potential mitigation actions is critical to ensure the durability of the fuel cell and their long-term stability. In this work, localized degradation of a solid oxide fuel cell is modeled in real-time and its effects on various cell parameters are analyzed. Profile distributions of overpotential, temperature, heat generation, and temperature gradients in the stack are investigated during degradation. Several causes of failure could occur in the fuel cell if no proper control actions are applied. A local analysis of critical parameters conducted shows where the issues are and how they could be mitigated in order to extend the life of the cell.

  18. Use of solar advanced oxidation processes for wastewater treatment: Follow-up on degradation products, acute toxicity, genotoxicity and estrogenicity.

    Science.gov (United States)

    Brienza, M; Mahdi Ahmed, M; Escande, A; Plantard, G; Scrano, L; Chiron, S; Bufo, S A; Goetz, V

    2016-04-01

    Wastewater tertiary treatment by advanced oxidation processes is thought to produce a treated effluent with lower toxicity than the initial influent. Here we performed tertiary treatment of a secondary effluent collected from a Waste Water Treatment Plant via homogeneous (solar/HSO5(-)/Fe(2+)) and heterogeneous (solar/TiO2) solar advanced oxidation aiming at the assessment of their effectiveness in terms of contaminants' and toxicity abatement in a plain solar reactor. A total of 53 organic contaminants were qualitatively identified by liquid chromatography coupled to high-resolution mass spectrometry after solid phase extraction. Solar advanced oxidation totally or partially removed the major part of contaminants detected within 4.5 h. Standard toxicity tests were performed using Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata and Brachionus calyciflorus organisms to evaluate acute and chronic toxicity in the secondary or tertiary effluents, and the EC50% was calculated. Estrogenic and genotoxic tests were carried out in an attempt to obtain an even sharper evaluation of potential hazardous effects due to micropollutants or their degradation by-products in wastewater. Genotoxic effects were not detected in effluent before or after treatment. However, we observed relevant estrogenic activity due to the high sensitivity of the HELN ERα cell line. PMID:26841289

  19. Identification of hydrolytic and isomeric N-oxide degradants of vilazodone by on line LC-ESI-MS/MS and APCI-MS.

    Science.gov (United States)

    Kalariya, Pradipbhai D; Talluri, M V N Kumar; Patel, Prinesh N; Srinivas, R

    2015-01-01

    The present study reports the degradation behavior of a new antidepressant drug, vilazodone, under various stress conditions as per International Conference on Harmonization guidelines (ICH, Q1A(R2). The investigation involved monitoring decomposition of the drug under hydrolytic (acidic, basic and neutral), oxidative, photolytic and thermal stress conditions and identifying degradation products. A rapid, precise, accurate and robust ultra high performance liquid chromatography (UPLC) method has been developed on a Waters CSH Phenyl-Hexyl column (100 mm × 2.1 mm, 1.7 μm) using gradient elution of 10mM ammonium acetate buffer (pH 5.0) and acetonitrile as mobile phase. The drug was found to be degraded in hydrolytic (acidic and basic) and oxidative conditions, whereas it was stable under neutral hydrolytic, photolytic and thermal stress conditions. The method was extended to quadrupole time-of-flight mass spectrometry (QTOF-MS) for the structural characterization of degradation products. It has been observed that isomeric N-oxide degradation products were formed under oxidative stress condition. The exact location of N-oxidation in the drug was investigated using atmospheric pressure chemical ionization (APCI) due to the formation of characteristic fragment ions. These fragment ions resulted from Meisenheimer rearrangement owing to thermal energy activation at the vaporizer of APCI source. All degradation products were comprehensively characterized by UPLC-ESI-MS/MS and UPLC-APCI-MS experiments. The most probable mechanisms for the formation of degradation products have also been proposed. The method was validated in terms of specificity, linearity, accuracy, precision, and robustness as per ICH guidelines. PMID:25459935

  20. Survey of microbial oxygenases: trichloroethylene degradation by propane-oxidizing bacteria.

    OpenAIRE

    Wackett, L P; Brusseau, G A; Householder, S R; Hanson, R S

    1989-01-01

    Microorganisms that biosynthesize broad-specificity oxygenases to initiate metabolism of linear and branched-chain alkanes, nitroalkanes, cyclic ketones, alkenoic acids, and chromenes were surveyed for the ability to biodegrade trichloroethylene (TCE). The results indicated that TCE oxidation is not a common property of broad-specificity microbial oxygenases. Bacteria that contained nitropropane dioxygenase, cyclohexanone monooxygenase, cytochrome P-450 monooxygenases, 4-methoxybenzoate monoo...

  1. Microstructural Degradation of Ni/YSZ Electrodes in Solid Oxide Electrolysis Cells under High Current

    DEFF Research Database (Denmark)

    Chen, Ming; Liu, Yi-Lin; Bentzen, Janet Jonna;

    2013-01-01

    Ni/yttria stabilized zirconia (YSZ) supported solid oxide electrolysis cells (SOECs) were exposed to long-term galvanostatic electrolysis tests, under different testing conditions (temperature, gas composition, current density etc.) with an emphasis on high current density (above −1 A/cm2...

  2. Investigation of the role of platinum oxide for the degradation of phenol under simulated solar irradiation

    NARCIS (Netherlands)

    Kibombo, Harrison S.; Wu, Chia-Ming; Peng, Rui; Baltrusaitis, Jonas; Koodali, Ranjit T.

    2013-01-01

    We demonstrate that a desired oxidation state can be achieved by synthetic colloidal methods and the choice of characterization technique is crucial for determining the physicochemical properties that influence the photocatalytic activities. XPS studies showed that PtO2 was realized in this study, a

  3. Degradation of Solid Oxide Electrolysis Cells Operated at High Current Densities

    DEFF Research Database (Denmark)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2014-01-01

    In this work the durability of solid oxide cells for co-electrolysis of steam and carbon dioxide (45 % H2O + 45 % CO2 + 10 % H2) at high current densities was investigated. The tested cells are Ni-YSZ electrode supported, with a YSZ electrolyte and either a LSM-YSZ or LSCF-CGO oxygen electrode...

  4. Photocatalytic Degradation of p-Cresol by Zinc Oxide under UV Irradiation

    OpenAIRE

    Nor Azah Yusof; Yadollah Abdollahi; Abdul Halim Abdullah; Zulkarnain Zainal

    2011-01-01

    Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO ...

  5. Design of Visible-light driven catalysts for water oxidation and VOC degradation

    OpenAIRE

    Thalluri, Sitaramanjaneya Mouli

    2015-01-01

    The PhD thesis involves one or more articles that are either published,submitted or in the process of manuscript preparation. These all chapters are eloborated in context to the understandings and advancements involved during the PhD period. The whole thesis involves insights about synthesis and characterization of BiVO4 in the form of powder as well as thin films. It also describes the ability of BiVO4 powders and thin films in water splitting and volatile organic compound degradation

  6. Electrochemical degradation of polycyclic aromatic hydrocarbons in creosote solution using ruthenium oxide on titanium expanded mesh anode

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Lan-Huong; Drogui, Patrick; Mercier, Guy [Institut National de la Recherche Scientifique (Centre Eau Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, C.P. 7500, Quebec, Qc G1K 9A9 (Canada); Blais, Jean-Francois, E-mail: blaisjf@ete.inrs.ca [Institut National de la Recherche Scientifique (Centre Eau Terre et Environnement), Universite du Quebec, 490 rue de la Couronne, C.P. 7500, Quebec, Qc G1K 9A9 (Canada)

    2009-05-30

    In this study, expanded titanium (Ti) covered with ruthenium oxide (RuO{sub 2}) electrode was used to anodically oxidize polycyclic aromatic hydrocarbons (PAH) in creosote solution. Synthetic creosote-oily solution (COS) was prepared with distilled water and a commercial creosote solution in the presence of an amphoteric surfactant; Cocamidopropylhydroxysultaine (CAS). Electrolysis was carried out using a parallelepipedic electrolytic 1.5-L cell containing five anodes (Ti/RuO{sub 2}) and five cathodes (stainless steel, 316L) alternated in the electrode pack. The effects of initial pH, temperature, retention time, supporting electrolyte, current density and initial PAH concentration on the process performance were examined. Experimental results revealed that a current density of 9.23 mA cm{sup -2} was beneficial for PAH oxidation. The sum of PAH concentrations for 16 PAHs could be optimally diminished up to 80-82% while imposing a residence time in the electrolysis cell of 90 min. There was not a significant effect of the electrolyte (Na{sub 2}SO{sub 4}) concentration on oxidation efficiency in the investigated range of 500-4000 mg/L. However, an addition of 500 mg Na{sub 2}SO{sub 4} L{sup -1} was required to reduce the energy consumption and the treatment cost. Besides, there was no effect of initial PAH concentration on oxidation efficiency in the investigated range of 270-540 mg PAH L{sup -1}. Alkaline media was not favourable for PAH oxidation, whereas high performance of PAH degradation could be recorded without initial pH adjustment (original pH around 6.0). Likewise, under optimal conditions, 84% of petroleum hydrocarbon (C{sub 10}-C{sub 50}) was removed, whereas removal yields of 69% and 62% have been measured for O and G and COD, respectively. Microtox and Daphnia biotests showed that electrochemical oxidation using Ti/RuO{sub 2} could be efficiently used to reduce more than 90% of the COS toxicity.

  7. Comparative Study of the Catalytic Activities of Three Distinct Carbonaceous Materials through Photocatalytic Oxidation, CO Conversion, Dye Degradation, and Electrochemical Measurements

    Science.gov (United States)

    Lee, Hangil; Kim, Yeonwoo; Kim, Min Ji; Kim, Ki-jeong; Kim, Byung-Kwon

    2016-01-01

    In order to compare the catalytic activities of reduced graphene oxide (rGO), graphene oxide (GO), and graphene, we conducted oxidation of 2-aminothiophenol (2-ATP) and reduction of nitrobenzene (NB) in their presence by using high-resolution photoemission spectroscopy (HRPES). In addition, we determined conversion rates of CO to CO2 in the presence of these catalysts by performing a residual gas analyzer (RGA) under a UHV condition, Orange II and methylene blue degradations UV-vis spectrophotometry, and electrochemistry (EC) measurements in an aqueous solution, as well as by obtaining cyclic voltammograms and determining the change of the condition of electrodes before and after the oxidation of 2-ATP. We found that we can successively fabricate GO (oxidation) and graphene (reduction) from rGO by controlling the oxidation or reduction procedure time and then clearly comparing the critical properties among them as we perform various oxidation and reduction activities. PMID:27762289

  8. Degradação de fármacos residuais por processos oxidativos avançados Degradation of residual pharmaceuticals by advanced oxidation processes

    Directory of Open Access Journals (Sweden)

    Silene Alessandra Santos Melo

    2009-01-01

    Full Text Available The concern about aquatic ecosystems and the potential risk of drinking water contamination by pharmaceuticals have stimulated the study of processes for the efficient degradation of these contaminants, since the conventional treatment have been inefficient on that purpose. The advanced oxidation processes (AOPs appear as viable alternatives due to their efficiency on the degradation of different classes of organic contaminants. This review presents an overview of the main AOP (O3, H2O2/UV, TiO2/UV, Fenton and photo-Fenton which have been applied to the degradation of different pharmaceuticals. The main results obtained, intermediates identified and toxicity data are presented.

  9. Degradation of Corn Oil Wastes by Fenton Reaction and Under Mildly Basic Media in the Presence of Oxidants Assisted with Sun Light

    Directory of Open Access Journals (Sweden)

    Josefina V.  Sanchez

    2008-01-01

    Full Text Available The degradation of water soluble corn oil wastes was carried out by Fenton reaction and also under mildly basic media in the presence of oxidants, such as hydrogen peroxide and persulfate, assisted with solar light. The degradation efficiency was obtained by analysis of chemical oxygen demand, carbon dioxide and gas chromatography. Over 90% of both chemical oxygen demand abatement and carbon dioxide recovery was accomplished by Fenton reaction. The presence of oxidants during the photodegradation resulted in high chemical oxygen demand abatement of the oil waste with the disappearance of the majority of the initial fatty acids present in the oil waste before treatment.

  10. Comparison of degradation reactions of Acid Yellow 61 in both oxidation processes of H2O2/UV and O3.

    Science.gov (United States)

    Wang, Y Z; Yedeler, A; Kettrup, A

    2001-07-01

    The comparison of degradation of Acid Yellow 61 as a model dye compound in both oxidation processes of H2O2/UV and O3 has been studied. When the decolorization rate of Acid Yellow 61 in both reactions presented similar, it was found there are some differences from the results of AOX removal and production of inorganic ions and organic acids. The results reveal that the H2O2/UV has beneficial effect on mineralization than O3 only for degradation of Acid Yellow 61 solution and it is possible for enhancement of method efficiency by taking longer reaction time and addition of high concentration of oxidants. PMID:11590760

  11. Bioaugmentation of biological contact oxidation reactor (BCOR) with phenol-degrading bacteria for coal gasification wastewater (CGW) treatment.

    Science.gov (United States)

    Fang, Fang; Han, Hongjun; Zhao, Qian; Xu, Chunyan; Zhang, Linghan

    2013-12-01

    This study was conducted to evaluate the performance of the biological contact oxidation reactor (BCOR) treating coal gasification wastewater (CGW) after augmented with phenol degrading bacteria (PDB). The PDB were isolated with phenol, 4-methyl phenol, 3,5-dimethyl phenol and resorcinol as carbon resources. Much of the refractory phenolic compounds were converted into easily-biodegradable compounds in spite of low TOC removal. The bioaugmentation with PDB significantly enhanced the removal of COD, total phenols (TP) and NH3-N, with efficiencies from 58% to 78%, 66% to 80%, and 5% to 25%, respectively. In addition, the augmented BCOR exhibited strong recovery capability in TP and COD removal while recovery of NH3-N removal needed longer time. Microbial community analysis revealed that the PDB presented as dominant populations in the bacteria consortia, which in turn determined the overall performance of the system.

  12. Discovery of LPMO activity on hemicelluloses shows the importance of oxidative processes in plant cell wall degradation

    DEFF Research Database (Denmark)

    Agger, Jane W.; Isaksen, Trine; Várnai, Anikó;

    2014-01-01

    of LPMOs, and considering the complexity and copolymeric nature of the plant cell wall, it has been speculated that some LPMOs may act on other substrates, in particular the hemicelluloses that tether to cellulose microfibrils. We demonstrate that an LPMO from Neurospora crassa, NcLPMO9C, indeed degrades...... walls. Products generated by NcLPMO9C were analyzed using high performance anion exchange chromatography and multidimensional mass spectrometry. We show that NcLPMO9C generates oxidized products from a variety of substrates and that its product profile differs from those of hydrolytic enzymes acting...... on the same substrates. The enzyme particularly acts on the glucose backbone of xyloglucan, accepting various substitutions (xylose, galactose) in almost all positions. Because the attachment of xyloglucan to cellulose hampers depolymerization of the latter, it is possible that the beneficial effect...

  13. Characterization of Series Resistance and Mobility Degradation Parameter and Optimizing Choice of Oxide Thickness in Thin Oxide N-Channel MOSFET

    Directory of Open Access Journals (Sweden)

    Noureddine Maouhoub

    2011-01-01

    Full Text Available We present two methods to extract the series resistance and the mobility degradation parameter in short-channel MOSFETs. The principle of the first method is based on the comparison between the exponential model and the classical model of effective mobility and for the second method is based on directly calculating the two parameters by solving a system of two equations obtained by using two different points in strong inversion at small drain bias from the characteristic (. The results obtained by these techniques have shown a better agreement with data measurements and allowed in the same time to determine the surface roughness amplitude and its influence on the maximum drain current and give the optimal oxide thickness.

  14. ZnO on Thiolated Graphene Oxide as Efficient Photocatalyst for Degradation of Methylene Blue

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Hyun; Choi, Hyun Chul [Chonnam National Univ., Gwangju (Korea, Republic of)

    2013-12-15

    We present here an efficient and simple method for preparation of highly active heterogeneous ZnO photo-catalyst (graphene oxide-zinc oxide: GO-ZnO), specifically by deposition of ZnO nanoparticles onto thiolated GOs. The resultant GO-ZnO sample was characterized by TEM, XRD, Auger, XPS, and Raman measurements, revealing that the size-similar and quasi-spherical ZnO nanoparticles were anchored to the thiolated GO surfaces. The average particle diameter was about 2.5 nm. In the photodegradation of methylene blue (MB) under ultraviolet (UV) light, GO-ZnO exhibited remarkably enhanced photocatalytic efficiency compared with thiolated GO and pure ZnO particles. This strong photocatalytic performance of GO-ZnO can be attributed to the suppression of electron recombination and the enhancement of mass transportation. The results showed that thiolated GO is the preferable supporting material.

  15. Degradation of progestagens by oxidation with potassium permanganate in wastewater effluents

    OpenAIRE

    Fayad, Paul B; Zamyadi, Arash; Broseus, Romain; Prévost, Michèle; Sauvé, Sébastien

    2013-01-01

    Background This study investigated the oxidation of selected progestagenic steroid hormones by potassium permanganate at pH 6.0 and 8.0 in ultrapure water and wastewater effluents, using bench-scale assays. Second order rate constants for the reaction of potassium permanganate with progestagens (levonorgestrel, medroxyprogesterone, norethindrone and progesterone) was determined as a function of pH, presence of natural organic matter and temperature. This work also illustrates the advantages o...

  16. Application of density functional theory (DFT) to study the properties and degradation of natural estrogen hormones with chemical oxidizers

    Energy Technology Data Exchange (ETDEWEB)

    Rokhina, Ekaterina V.; Suri, Rominder P.S., E-mail: rominder.suri@temple.edu

    2012-02-15

    Estrone (E1), 17{beta}-estradiol (E2), estriol (E3), equilin (EQ) and 17{alpha}-estradiol (17{alpha}) estrogen hormones are released by humans and animals and have been detected in the environment and municipal wastewater treatment plants. The structural and electronic properties of natural hormone molecules are investigated by performing density functional theory calculations and used to predict their properties and chemical behavior. Quantitative structure property relationship (QSPR) approach is applied to correlate the estrogenicity associated with the natural estrogen hormones according to their molecular properties. The obtained relationship reveals the importance of the frontier molecular orbital energy in the interpretation of estrogenic activity of hormones, which is consistent with the previous research. Moreover, the obtained molecular descriptors also aid determination of the degradability of hormones, and to rationalize degradation pathways, with chemical oxidizers such as ozone and hydroxyl radical. Both types of interactions belong to the orbital-controlled reactions. The active sites determined by Fukui functions for the estrogen hormone molecules confirm the reaction pattern that initiates the attack of the aromatic ring for both ozone and hydroxyl radical. The reactive sites of the molecules are mapped with subsequent reaction intermediates and compared with experimental data obtained from the literature. - Highlights: Black-Right-Pointing-Pointer DFT methods described in this paper are suitable for predicting the degradation behavior of natural estrogen hormones. Black-Right-Pointing-Pointer Using QSAR, the estrogenicity of natural hormones was determined by DFT descriptors. Black-Right-Pointing-Pointer The sites of primary ozone and hydroxyl radical attack were predicted using DFT, and findings confirmed by experimental data.

  17. Kinetic modeling of native Cassava starch thermo-oxidative degradation using Weibull and Weibull-derived models.

    Science.gov (United States)

    Janković, Bojan

    2014-01-01

    A new approach in kinetic modeling of thermo-oxidative degradation process of starch granules extracted from the Cassava roots was developed. Based on the thermoanalytical measurements, three reaction stages were detected. Using Weibull and Weibull-derived (inverse) models, it was found that the first two reaction stages could be described with the change of apparent activation energy (Ea) on conversion fraction (α(T)) (using "Model-free" analysis). It was found that first reaction stage, which involves dehydration and evaporation of lower molecular mass fractions, can be described with an inverse Weibull model. This model with its distribution of Ea values and derived distribution parameters includes the occurrence of three-dimensional diffusion mechanism. The second reaction stage is very complex, and it was found to contain the system of simultaneous reactions (where depolymerization occurs), and can be described with standard Weibull model. Identified statistical model with its distribution of Ea values and derived distribution parameters includes the kinetic model that gives the variable reaction order values. Based on the established models, shelf-life studies for first two stages were carried out. Shelf-life testing has shown that optimal dehydration time is achieved by a programmed heating at medium heating rate, whereas optimal time of degradation is achieved at highest heating rate.

  18. Novel activated alumina-supported iron oxide-composite as a heterogeneous catalyst for photooxidative degradation of reactive black 5

    Energy Technology Data Exchange (ETDEWEB)

    Hsueh, C.L. [Department of Chemical Engineering, National Cheng Kung University, Tainan City 701, Taiwan (China); Huang, Y.H. [Department of Chemical Engineering, National Cheng Kung University, Tainan City 701, Taiwan (China); Chen, C.Y. [Department of Chemical Engineering, National Cheng Kung University, Tainan City 701, Taiwan (China)]. E-mail: ccy7@ccmail.ncku.edu.tw

    2006-02-28

    A novel activated alumina-supported iron oxide-composite (denoted as FeAA-500) was prepared by so-called fluidized-bed reactor (FBR) crystallization. X-ray powder diffraction (XRD), N{sub 2} adsorption/desorption, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to characterize the FeAA-500. The photo-catalytic activity of the FeAA-500 was evaluated in the photooxidative degradation of 0.1 mM azo-dye reactive black 5 (RB5) in the presence of H{sub 2}O{sub 2} and UVA light ({lambda} = 365 nm) in a solution with a pH of 2.5. Complete decolorization of the model pollutant RB5 was achieved; the total organic carbon (TOC) removal ratio was 95%, and a trace amount of leached ferric ion was detected following 75 min of reaction when 2.0 g/L FeAA-500 was used as a catalyst. FeAA-500 has high photo-catalytic activity; it is therefore a promising heterogeneous photocatalysis of the degradation of organic compounds.

  19. Reduced graphene oxide–cuprous oxide composite via facial deposition for photocatalytic dye-degradation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, MingYan, E-mail: mingyanlyg@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Huang, JunRao; Tong, ZhiWei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Li, WeiHua [School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia); Chen, Jun, E-mail: junc@uow.edu.au [Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, Australian Institute of Innovative Materials, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522 (Australia)

    2013-08-15

    Highlights: •Cubic Cu{sub 2}O were effectively loaded on n-propylamine (PA) intercalated graphene oxide. •The addition of PA on the carbon sheets supports the stable structure of the composites. •Cu{sub 2}O/PA/rGO showed superior adsorption capacity and photocatalytic activity. -- Abstract: Cubic Cu{sub 2}O nanoparticles have been successfully synthesized on n-propylamine (PA) intercalated graphene oxide (GO) with uniform distribution followed with a subsequent hydrazine hydrate reduction process to generate Cu{sub 2}O/PA/rGO composite. For comparison, Cu{sub 2}O conjugated reduced graphene oxide (Cu{sub 2}O/rGO) composite was also synthesized using the same method. The as-prepared Cu{sub 2}O/PA/rGO and Cu{sub 2}O/rGO nanocomposites are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) spectroscopy, infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area analysis, and Electrochemical impedance spectra (EIS) measurements. UV/vis diffuse reflectance spectroscopy was employed to estimate band gap energies of cuprous oxide composites. The results show that the intercalation of PA into the layered GO increases the surface area of the composites and provides an efficient strategy to load Cu{sub 2}O due to the large and uniform distribution of active sites for anchoring copper ions. The surface area of the Cu{sub 2}O/PA/rGO (123 m{sup 2}/g) nanocomposite was found to be almost 2.5 times higher than that of Cu{sub 2}O/rGO (55.7 m{sup 2}/g). The as-prepared Cu{sub 2}O/PA/rGO show significant improvement on both adsorption capacity and photocatalytic activity towards organic pigment pollution compared with Cu{sub 2}O/rGO under identical performance conditions.

  20. Kinetic behavior of anti-inflammatory drug ibuprofen in aqueous medium during its degradation by electrochemical advanced oxidation.

    Science.gov (United States)

    Ambuludi, Silvia Loaiza; Panizza, Marco; Oturan, Nihal; Özcan, Ali; Oturan, Mehmet A

    2013-04-01

    The electrochemical abatement of the drug ibuprofen (2-(4-isobutylphenyl)propionic acid) from aqueous solution has been carried out by anodic oxidation. The electrolyses have been performed at constant current using a small, undivided cell equipped with a Pt or thin-film boron-doped diamond (BDD) anode and a carbon-felt cathode. The results have shown that ibuprofen has been destroyed under all the conditions tested, following pseudo-first-order kinetics; however, BDD enables higher removal rates than Pt, because the former produces greater quantity of (•)OH. Using BDD anode, the pseudo-first-order rate constant increased with applied current and when NaCl replaced Na2SO4 as supporting electrolyte, while it is almost unaffected by ibuprofen concentration. Mineralization of ibuprofen aqueous solutions was followed by total organic carbon (TOC) measurements. After 8 h of electrolysis, TOC removal varied from 91% to 96% applying a current in the range of 50-500 mA. The reaction by-products were quantified by chromatographic techniques, and in particular, aliphatic acids (oxalic, glyoxylic, formic, acetic, and pyruvic) have been the main intermediates formed during the electrolyses. The absolute rate constant for the oxidative degradation of ibuprofen have also been determined, by competition kinetic method, as 6.41 × 10(9) M(-1) s(-1). PMID:22903814

  1. Degradation of solid oxide cells during co-electrolysis of steam and carbon dioxide at high current densities

    Science.gov (United States)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2016-10-01

    In this work, the durability of Ni-YSZ based solid oxide cells was investigated during co-electrolysis of steam and carbon dioxide (45% H2O + 45% CO2 + 10% H2) at current density of -1.5 or -2.0 A cm-2. The cell consists of ∼300 μm Ni-YSZ support, ∼10 μm Ni-YSZ electrode, ∼10 μm YSZ electrolyte and ∼15 μm LSM-YSZ oxygen electrode. The gas conversion was 45% at -1.5 A cm-2 and 60% at -2.0 A cm-2, and the operating durations were up to 700 h. The detailed electrochemical analysis revealed significant increase of the ohmic resistance, oxide ion transport resistance in the Ni-YSZ composite electrodes and the electrochemical reaction resistance at the Ni-YSZ triple-phase boundaries. The performance degradation is mainly ascribed to the microstructural change in the Ni-YSZ electrode close to the YSZ electrolyte, including the percolation loss of Ni, the contact loss between Ni and YSZ electrolyte and the decomposition of YSZ close to Ni-YSZ|YSZ interface. The electrochemical performance and the microstructure of the oxygen electrode were found to be relatively stable.

  2. ZnO nanowire/reduced graphene oxide nanocomposites for significantly enhanced photocatalytic degradation of Rhodamine 6G

    Science.gov (United States)

    Zhang, Chao; Zhang, Jing; Su, Yanjie; Xu, Minghan; Yang, Zhi; Zhang, Yafei

    2014-02-01

    We have demonstrated a facile and low-cost approach to synthesize ZnO nanowire (NW)/reduced graphene oxide (RGO) nanocomposites, in which ZnO NWs and graphene oxide (GO) were produced in large scale separately and then hybridized into ZnO NW/RGO nanocomposites by mechanical mixing and low-temperature thermal reduction. Rhodamine 6G (Rh6G) was used as a model dye to evaluate the photocatalytic properties of ZnO NW/RGO nanocomposites. The obtained nanocomposites show significantly enhanced photocatalytic performance, which took only 10 min to decompose over 98% Rh6G. Finally the mechanism of the great enhancement about photocatalytic activity of ZnO NW/RGO nanocomposites is studied. It is mainly attributed to that RGO nanosheets can transfer the electrons of ZnO NWs excited by ultraviolet (UV) irradiation, increase electron migration efficiency, and then longer the lifetime of the holes in ZnO NWs. The high charge separation efficiency of photo-generated electron-hole pairs directly leads to the lower recombination rate of ZnO NW/RGO nanocomposites, makes more effective electrons and holes to participate the radical reactions with Rh6G, thus significantly improving the photocatalytic properties. The high degradation efficiency makes the ZnO NW/RGO nanocomposites promising candidates in the application of environmental pollutant and wastewater treatment.

  3. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Thyden, K.

    2008-03-15

    Ni-YSZ cermets have been used as anode materials in SOFCs for more than 20 years. Despite this fact, the major cause of degradation within the Ni-YSZ anode, namely Ni sintering / coarsening, is still not fully understood. Even if microstructural studies of anodes in tested cells are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused on improving microstructural techniques and shows that the application of low acceleration voltages (<= 1 kV) in a FE-SEM makes it possible to obtain two useful types of contrast between the phases in Ni-YSZ composites. By changing between the ordinary lateral SE detector and the inlens detector, using similar microscope settings, two very different sample characteristics are probed: 1) The difference in secondary emission coefficient, delta, between the percolating and non-percolating Ni is maximized in the low-voltage range due to a high delta for the former and the suppression of delta by a positive charge for the latter. This difference yields a contrast between the two phases which is picked up by an inlens secondary electron detector. 2) The difference in backscatter coefficient, eta, between Ni and YSZ is shown to increase with decreasing voltage. The contrast is illustrated in images collected by the normal secondary detector since parts of the secondary signals are generated by backscattered electrons. High temperature aging experiments of model Ni-YSZ anode cermets show

  4. Coupling membrane separation and photocatalytic oxidation processes for the degradation of pharmaceutical pollutants.

    Science.gov (United States)

    Martínez, F; López-Muñoz, M J; Aguado, J; Melero, J A; Arsuaga, J; Sotto, A; Molina, R; Segura, Y; Pariente, M I; Revilla, A; Cerro, L; Carenas, G

    2013-10-01

    The coupling of membrane separation and photocatalytic oxidation has been studied for the removal of pharmaceutical pollutants. The retention properties of two different membranes (nanofiltration and reverse osmosis) were assessed. Comparable selectivity on the separation of pharmaceuticals were observed for both membranes, obtaining a permeate stream with concentrations of each pharmaceutical below 0.5 mg L(-)(1) and a rejected flux highly concentrated (in the range of 16-25 mg L(-)(1) and 18-32 mg L(-)(1) of each pharmaceutical for NF-90 and BW-30 membranes, respectively), when an initial stream of six pharmaceuticals was feeding to the membrane system (10 mg L(-)(1) of each pharmaceutical). The abatement of concentrated pharmaceuticals of the rejected stream was evaluated by means of heterogeneous photocatalytic oxidation using TiO2 and Fe2O3/SBA-15 in presence of hydrogen peroxide as photo-Fenton system. Both photocatalytic treatments showed remarkable removals of pharmaceutical compounds, achieving values between 80 and 100%. The nicotine was the most refractory pollutant of all the studied pharmaceuticals. Photo-Fenton treatment seems to be more effective than TiO2 photocatalysis, as high mineralization degree and increased nicotine removal were attested. This work can be considered an interesting approach of coupling membrane separation and heterogeneous photocatalytic technologies for the successful abatement of pharmaceutical compounds in effluents of wastewater treatment plants. PMID:23863375

  5. Oxidative Debromination and Degradation of Tetrabromo-bisphenol A by a Functionalized Silica-Supported Iron(III-tetrakis(p-sulfonatophenylporphyrin Catalyst

    Directory of Open Access Journals (Sweden)

    Masami Fukushima

    2013-05-01

    Full Text Available Tetrabromobisphenol A (TBBPA, a commonly used brominated flame retardant, also functions as an endocrine disruptor. Thus, the degradation of TBBPA has attracted considerable interest among the scientific community. Iron(III-porphyrin complexes are generally regarded as “green” catalysts and have been reported to catalyze the efficient degradation and dehalogenation of halogenated phenols in environmental wastewaters. However, they are quickly deactivated due to self-degradation in the presence of an oxygen donor, such as KHSO5. In the present study, an iron(III-tetrakis (p-sulfonatophenyl-porphyrin (FeTPPS was immobilized on imidazole-modified silica (FeTPPS/IPS via coordination of the Fe(III with the nitrogen atom in imidazole to suppress self-degradation and thus enhance the catalyst reusability. The oxidative degradation and debromination of TBBPA and the influence of humic acid (HA, a major component in leachates, on the oxidation of TBBPA was investigated. More than 95% of the TBBPA was degraded in the pH range from 3 to 8 in the absence of HA, while the optimal pH for the reaction was at pH 8 in the presence of HA. Although the rate of degradation was decreased in the presence of HA, over 95% of the TBBPA was degraded within 12 h in the presence of 28 mg-C L−1 of HA. At pH 8, the FeTPPS/IPS catalyst could be reused up to 10 times without any detectable loss of activity for TBBPA for degradation and debromination, even in the presence of HA.

  6. Hot-carrier degradation for 90 nm gate length LDD-NMOSFET with ultra-thin gate oxide under low gate voltage stress

    Institute of Scientific and Technical Information of China (English)

    Chen Hai-Feng; Hao Yue; Ma Xiao-Hua; Li Kang; Ni Jin-Yu

    2007-01-01

    The hot-carrier degradation for 90 nm gate length lightly-doped drain (LDD) NMOSFET with ultra-thin (1.4 nm) gate oxide under the low gate voltage (LGV) (at Vg=Vth,where Vth is the threshold voltage) stress has been investigated.It is found that the drain current decreases and the threshold voltage increases after the LGV (Vg=Yth) stress.The results are opposite to the degradation phenomena of conventional NMOSFET for the case of this stress.By analysing the gate-induced drain leakage (GIDL) current before and after stresses,it is confirmed that under the LGV stress in uItra-short gate LDD-NMOSFET with ultra-thin gate oxide,the hot holes are trapped at interface in the LDD region and cannot shorten the channel to mask the influence of interface states as those in conventional NMOSFET do.which leads to the different degradation phenomena from those of the conventional NMOS devices.This paper also discusses the degradation in the 90 nm gate length LDD-NMOSFET with 1.4 nm gate oxide under the LGV stress at Vg=Vth with various drain biases.Experimental results show that the degradation slopes(n) range from 0.21 to 0.41.The value of n is less than that of conventional MOSFET(0.5-0.6) and also that of the long gate length LDD MOSFET (~0.8).

  7. Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Degradation of 2,4-dichlorophenol (2,4-DCP) was studied in a novel three-electrode photoelectrocatalytic (PEC) integrative oxidation process, and the factors influencing the degradation rate, such as applied current, flow speed of O2, pH, adscititious voltage and initial 2,4-DCP concentration were investigated and optimized. H2O2 was produced nearby cathode and Fe2+ continuously generated from Fe anode in solution when current and O2 was applied, so, main reactions, H2O2-assisted TiO2 PEC oxidation and E-Fenton reaction, occurred during degradation of 2,4-DCP in this integrative system. The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process, while it was only 31% in E-Fenton process and 46% in H2O2-assisted TiO2 PEC process. So, it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect. By the investigation of pH, it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.

  8. TiO2-Based Photocatalytic Geopolymers for Nitric Oxide Degradation

    Directory of Open Access Journals (Sweden)

    Alberto Strini

    2016-06-01

    Full Text Available This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin, composite systems (siloxane-hybrid, foamed hybrid, and curing temperatures (room temperature and 60 °C were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste. The geopolymer matrices were previously designed for different applications, ranging from insulating (foam to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM and energy dispersive X-ray (EDS analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

  9. Phenol Photocatalytic Degradation by Advanced Oxidation Process under Ultraviolet Radiation Using Titanium Dioxide

    Directory of Open Access Journals (Sweden)

    Ali Nickheslat

    2013-01-01

    Full Text Available Background. The main objective of this study was to examine the photocatalytic degradation of phenol from laboratory samples and petrochemical industries wastewater under UV radiation by using nanoparticles of titanium dioxide coated on the inner and outer quartz glass tubes. Method. The first stage of this study was conducted to stabilize the titanium dioxide nanoparticles in anatase crystal phase, using dip-coating sol-gel method on the inner and outer surfaces of quartz glass tubes. The effect of important parameters including initial phenol concentration, TiO2 catalyst dose, duration of UV radiation, pH of solution, and contact time was investigated. Results. In the dip-coat lining stage, the produced nanoparticles with anatase crystalline structure have the average particle size of 30 nm and are uniformly distributed over the tube surface. The removal efficiency of phenol was increased with the descending of the solution pH and initial phenol concentration and rising of the contact time. Conclusion. Results showed that the light easily passes through four layers of coating (about 105 nm. The highest removal efficiency of phenol with photocatalytic UV/TiO2 process was 50% at initial phenol concentration of 30 mg/L, solution pH of 3, and 300 min contact time. The comparison of synthetic solution and petrochemical wastewater showed that at same conditions the phenol removal efficiency was equal.

  10. Rapid photo-degradation of 2-chlorophenol under visible light irradiation using cobalt oxide-loaded TiO2/reduced graphene oxide nanocomposite from aqueous media.

    Science.gov (United States)

    Sharma, Ajit; Lee, Byeong-Kyu

    2016-01-01

    The photocatalytic removal of 2-chlorophenol (2-CP) from water environment was investigated by TiO2-RGO-CoO. Cobalt oxide-loaded TiO2 (TiO2-CoO) supported with reduced graphene oxide (RGO) was synthesized using a sol-gel method and then annealed at 500 °C for 5 min. The material characteristics were analyzed by UV-Vis analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Incorporation of cobalt oxide and RGO into the TiO2 system (TiO2-RGO-CoO) lowered the band gap energy to 2.83 eV, which greatly enhanced the visible light absorption. The TiO2-RGO-CoO photocatalyst showed complete removal of 20 mg/L 2-CP within 8 h with the addition of 0.01% H2O2 under 100 W visible light irradiation. The photo-degradation efficiency of 2-CP (10 mg/L) was 35.2, 48.9, 58.9 and 98.2% for TiO2, TiO2-RGO, TiO2-CoO and TiO2-RGO-CoO, respectively, in the presence of visible light irradiation at solution pH of 6.0. The TiO2-RGO-CoO photocatalyst retained its high removal efficiency even after five photocatalytic cycles. PMID:26386660

  11. The influence of atmospheric species on the degradation of aluminum doped zinc oxide and Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.J.; Foster, C.; Dasgupta, S.; Vroon, Z.A.E.P.; Barreau, N.; Zeman, M.

    2014-01-01

    Aluminum doped zinc oxide (ZnO:Al) layers were exposed to the atmospheric gases carbondioxide (CO2), oxygen (O2), nitrogen (N2) and air as well as liquid H2O purged with these gases, in order to investigate the chemical degradation behavior of these layers. The samples were analyzed by electrical, c

  12. A non-acid-assisted and non-hydroxyl-radical-related catalytic ozonation with ceria supported copper oxide in efficient oxalate degradation in water

    KAUST Repository

    Zhang, Tao

    2012-06-01

    Oxalate is usually used as a refractory model compound that cannot be effectively removed by ozone and hydroxyl radical oxidation in water. In this study, we found that ceria supported CuO significantly improved oxalate degradation in reaction with ozone. The optimum CuO loading amount was 12%. The molar ratio of oxalate removed/ozone consumption reached 0.84. The catalytic ozonation was most effective in a neutral pH range (6.7-7.9) and became ineffective when the water solution was acidic or alkaline. Moreover, bicarbonate, a ubiquitous hydroxyl radical scavenger in natural waters, significantly improved the catalytic degradation of oxalate. Therefore, the degradation relies on neither hydroxyl radical oxidation nor acid assistance, two pathways usually proposed for catalytic ozonation. These special characters of the catalyst make it suitable to be potentially used for practical degradation of refractory hydrophilic organic matter and compounds in water and wastewater. With in situ characterization, the new surface Cu(II) formed from ozone oxidation of the trace Cu(I) of the catalyst was found to be an active site in coordination with oxalate forming multi-dentate surface complex. It is proposed that the complex can be further oxidized by molecular ozone and then decomposes through intra-molecular electron transfer. The ceria support enhanced the activity of the surface Cu(I)/Cu(II) in this process. © 2012 Elsevier B.V.

  13. Low-temperature oxidative degradation of PBX 9501 and its components determined via molecular weight analysis of the poly [ester urethane] binder

    Energy Technology Data Exchange (ETDEWEB)

    Kress, Joel D [Los Alamos National Laboratory

    2008-01-01

    The results of following the oxidative degradation of a plastic-bonded explosive (PBX 9501) are reported. Into over 1100 sealed containers were placed samples of PBX 9501 and combinations of its components and aged at relatively low temperatures to induce oxidative degradation of the samples. One of the components of the explosive is a poly(ester urethane) polymer and the oxidative degradation of the samples were following by measuring the molecular weight change of the polymer by gel permeation chromatography (coupled with both differential refractive index and multiangle laser light scattering detectors). Multiple temperatures between 40 and 64 {sup o}C were used to accelerate the aging of the samples. Interesting induction period behavior, along with both molecular weight increasing (crosslinking) and decreasing (chain scissioning) processes, were found at these relatively mild conditions. The molecular weight growth rates were fit to a random crosslinking model for all the combinations of components. The fit rate coefficients show Arrhenius behavior and activation energies and frequency factors were obtained. The kinetics of molecular weight growth shows a compensatory effect between the Arrhenius prefactors and activation energies, suggesting a common degradation process between PBX 9501 and the various combinations of its constituents. An oxidative chemical mechanism of the polymer is postulated, consistent with previous experimental results, that involves a competition between urethane radical crosslinking and carbonyl formation.

  14. Physical and chemical degradation behavior of sputtered aluminum doped zinc oxide layers for Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Theelen, M.; Boumans, T.; Stegeman, F.; Colberts, F.; Illiberi, A.; Berkum, J. van; Barreau, N.; Vroon, Z.; Zeman, M.

    2014-01-01

    Sputtered aluminum doped zinc oxide (ZnO:Al) layers on borosilicate glass were exposed to damp heat (85 C/85% relative humidity) for 2876 h to accelerate the physical and chemical degradation behavior. The ZnO:Al samples were characterized by electrical, compositional and optical measurements before

  15. Oxide degradation effects in dry patterning of resist using neutral oxygen beams

    International Nuclear Information System (INIS)

    Novel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, after MOSFET gate oxide quality, impacting device performance and reliability. We have studied this processing related device integrity issue by subjecting polysilicon gas MOS structures to exposure treatments similar to those used in resist patterning using low energy oxygen beams. Electrical C-V characterization shows a significant increase in the oxide trapped charge and interface state density upon low energy exposure. I-V and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25-V to 0.5-V negative flatband shifts can be partially annealed by the carrier injection. This could be due to positive charge annihilation or electron trapping, or some combination of both. Physical and analysis of patterned resist layers and electrical characterization data of MOS structures exposed to different neutral beam processing environments and following thermal annealing treatments is presented

  16. Interindividual variation in binding of benzo[a]pyrene to DNA in cultured human Bronchi

    DEFF Research Database (Denmark)

    Harris, C.C.; Autrup, Herman; Connor, R.;

    1976-01-01

    The binding of benzo[a]pyrene to DNA in cultured human bronchus was measured in specimens from 37 patients. The binding values ranged from 2 to 151 picomoles of benzo[a]pyrene per milligram of DNA with an overall mean +/- standard error of 34.2 +/- 5.2. This 75-fold interindividual variation in t...

  17. Simple Fluorimetric Determination of Benzo[a]pyrene in Cigarette Smoke without Preseparation Procedure

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Constant-energy synchronous fluorimetry was used for the identification of benzo[a]pyrene in mixtures with a detection limit of 1.34 nmol/L. The recovery experiments in cigarette smoke samples have also obtained satisfactory results of 99.1-103.5% for benzo[a]pyrene.

  18. Degradation of some ceria electrolytes under hydrogen contact nearby anode in solid oxide fuel cells (SOFCs

    Directory of Open Access Journals (Sweden)

    Malta Luiz Fernando Brum

    2004-01-01

    Full Text Available This work is concerned with thermodynamic analysis of the stability of some ceria electrolytes under contact with hydrogen gas nearby anode in fuel cells. It was considered the following types of ceria-electrolytes: pure ceria, strontium-doped ceria, calcium-doped ceria and calcium-bismuth-doped ceria. The equilibrium Log (pH2O/pH2 vs. T diagrams were constructed for x = 0.1 and 0.01, where x is the fraction of initial ceria converted to Ce2O3 (proportional to the ratio between activities of Ce3+ and Ce4+ in the ceria electrolyte, which is proportional to the fraction of electronic conduction in the electrolyte at a given temperature. The predictions of the diagrams are as follows: (a Ce1.9Ca0.1Bi0.8O5.1 and Ce0.9Sr0.1O1.9 are less stable than pure ceria for the whole temperature range (from 0 to 1000 °C; (b Ce0.9Ca0.1O1.9 is more stable than pure ceria below about 650 °C for x = 0.1 and below about 400 °C for x = 0.01; (c at each temperature in the considered range the pressure ratio pH2O(g/pH2(g has to be higher than thermodynamically predicted in order to keep CeO2 stable in the electrolyte contacting hydrogen gas. Thermodynamic predictions are entirely capable of explaining experimental data published on the subject (irreversible cell degradation in the case of SrO-doped ceria; weight loss from doped-ceria electrolyte above 700 °C; oxygen gas release during sintering of ceria.

  19. Oxidative Degradation of κ-Carrageenan%к-卡拉胶的氧化降解

    Institute of Scientific and Technical Information of China (English)

    李桂村; 张志焜; 耿美玉

    2002-01-01

    к-卡拉胶有着良好的药理和生理活性,但是由于分子量大,溶解性差使它的应用受到很大的限制.研究了在中性和酸性条件下利用H2O2对卡拉胶进行降解来制备低分子量的卡拉胶时H2O2浓度、卡拉胶浓度、反应温度和时间对反应的影响.发现提高H2O2浓度、降低卡拉胶浓度、提高反应温度有利于卡拉胶分子量的降低.通过粘度法测量了卡拉胶的平均分子量在1000~10000,并发现它的溶解性大大提高了.利用IR和13C-NMR研究了降解前后卡拉胶的结构变化.%κ-carrageenan has helpful physiological and pharmacological activities, but its applications on medicine are limited due to its high molecular weight and bad solubility. The κ-carrageenan low molecular weight (LMW) by hydrogen peroxide (H2O2) was produced firstly in the neutral and acid conditions. The effects of concentration of hydrogen peroxide, the ratio of reactants, reaction temperature and time were discussed. The average molecular weight (AMW) of κ-carrageenan was measured by viscosity method. The AMW varied from 1000 to 10000 and solubility was increased greatly. The chemical structure and the mechanism of degradation were studied by 13C-NMR and IR spectra.

  20. Degradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils by Fenton's reagent: a multivariate evaluation of the importance of soil characteristics and PAH properties.

    Science.gov (United States)

    Jonsson, Sofia; Persson, Ylva; Frankki, Sofia; van Bavel, Bert; Lundstedt, Staffan; Haglund, Peter; Tysklind, Mats

    2007-10-01

    In this study, we investigated how the chemical degradability of polycyclic aromatic hydrocarbons (PAHs) in aged soil samples from various contaminated sites is influenced by soil characteristics and by PAH physico-chemical properties. The results were evaluated using the multivariate statistical tool, partial least squares projections to latent structures (PLS). The PAH-contaminated soil samples were characterised (by pH, conductivity, organic matter content, oxide content, particle size, specific surface area, and the time elapsed since the contamination events, i.e. age), and subjected to relatively mild, slurry-phase Fenton's reaction conditions. In general, low molecular weight PAHs were degraded to a greater extent than large, highly hydrophobic variants. Anthracene, benzo(a)pyrene, and pyrene were more susceptible to degradation than other, structurally similar, PAHs; an effect attributed to the known susceptibility of these compounds to reactions with hydroxyl radicals. The presence of organic matter and the specific surface area of the soil were clearly negatively correlated with the degradation of bi- and tri-cyclic PAHs, whereas the amount of degraded organic matter correlated positively with the degradation of PAHs with five or six fused rings. This was explained by enhanced availability of the larger PAHs, which were released from the organic matter as it degraded. Our study shows that sorption of PAHs is influenced by a combination of soil characteristics and physico-chemical properties of individual PAHs. Multivariate statistical tools have great potential for assessing the relative importance of these parameters.

  1. Catalytic degradation of Acid Orange 7 by manganese oxide octahedral molecular sieves with peroxymonosulfate under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Lian; Sun, Binzhe; Wei, Mingyu; Luo, Shilu; Pan, Fei; Xu, Aihua [School of Environmental Engineering, Wuhan Textile University, Wuhan 430073 (China); Li, Xiaoxia, E-mail: lixxwh@163.com [School of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan 430073 (China)

    2015-03-21

    Highlights: • OMS-2/PMS/Vis system could efficiently catalyze the degradation of organic dyes. • The system showed much higher activity than that of OMS-2/PMS and OMS-2/Vis. • The OMS-2 catalyst exhibited stable performance for multiple runs. • Sulfate radicals were suggested to be the major reactive species in the system. • The radicals production might involve the redox cycle of Mn(IV)/Mn(III) and Mn(III)/Mn(II). - Abstract: In this paper, the photodegradation of Acid Orange 7 (AO7) in aqueous solutions with peroxymonosulfate (PMS) was studied with manganese oxide octahedral molecular sieves (OMS-2) as the catalyst. The activities of different systems including OMS-2 under visible light irradiation (OMS-2/Vis), OMS-2/PMS and OMS-2/PMS/Vis were evaluated. It was found that the efficiency of OMS-2/PMS was much higher than that of OMS-2/Vis and could be further enhanced by visible light irradiation. The catalyst also exhibited stable performance for multiple runs. Results from ESR and XPS analyses suggested that the highly catalytic activity of the OMS-2/PMS/Vis system possible involved the activation of PMS to sulfate radicals meditated by the redox pair of Mn(IV)/Mn(III) and Mn(III)/Mn(II), while in the OMS-2/PMS system, only the redox reaction between Mn(IV)/Mn(III) occurred. Several operational parameters, such as dye concentration, catalyst load, PMS concentration and solution pH, affected the degradation of AO7.

  2. Reduced graphene oxide nanosheets decorated with Au-Pd bimetallic alloy nanoparticles towards efficient photocatalytic degradation of phenolic compounds in water

    Science.gov (United States)

    Darabdhara, Gitashree; Boruah, Purna K.; Borthakur, Priyakshree; Hussain, Najrul; Das, Manash R.; Ahamad, Tansir; Alshehri, Saad M.; Malgras, Victor; Wu, Kevin C.-W.; Yamauchi, Yusuke

    2016-04-01

    Reduced graphene oxide nanosheets decorated with Au-Pd bimetallic alloy nanoparticles are successfully prepared via a chemical approach consisting of reducing the metal precursors using ascorbic acid as reductant at an elevated temperature. The prepared nanocomposite is employed as a photocatalyst for the degradation of organic contaminants such as phenol, 2-chlorophenol (2-CP), and 2-nitrophenol (2-NP). The complete degradation of phenol is achieved after 300 min under natural sunlight irradiation whereas the degradation of 2-CP and 2-NP is completed after 180 min. The activity of the photocatalyst is evaluated considering several parameters such as the initial phenol concentration, the photocatalyst loading, and the pH of the solution. The degradation kinetics of all the compounds is carefully studied and found to follow a linear Langmuir-Hinshelwood model. Furthermore, the reusability of the photocatalyst is successfully achieved up to five cycles and the catalyst exhibits an excellent stability.Reduced graphene oxide nanosheets decorated with Au-Pd bimetallic alloy nanoparticles are successfully prepared via a chemical approach consisting of reducing the metal precursors using ascorbic acid as reductant at an elevated temperature. The prepared nanocomposite is employed as a photocatalyst for the degradation of organic contaminants such as phenol, 2-chlorophenol (2-CP), and 2-nitrophenol (2-NP). The complete degradation of phenol is achieved after 300 min under natural sunlight irradiation whereas the degradation of 2-CP and 2-NP is completed after 180 min. The activity of the photocatalyst is evaluated considering several parameters such as the initial phenol concentration, the photocatalyst loading, and the pH of the solution. The degradation kinetics of all the compounds is carefully studied and found to follow a linear Langmuir-Hinshelwood model. Furthermore, the reusability of the photocatalyst is successfully achieved up to five cycles and the catalyst

  3. Detoxification of azinophos methyl using gamma radiation mediated advance oxidation process and investigation of degradation products by HPLC and GC-MS

    International Nuclear Information System (INIS)

    Gamma radiolytic degradation of azinophos-methyl was studied in water and methanol separately, using 60Co as a radiation source under varied experimental conditions. Solution of azinophos-methyl was prepared in pure methanol at concentration of 50 μg ml-1, irradiated at gamma dose of 1 to 7 kGy and high performance liquid chromatography (HPLC) coupled with diode array detector was used to monitor the extent of degradation along with numbers of degradation products. At dose of 7 kGy ≥ 99% of azinophos-methyl was degraded. The degradation occurred by interaction of CH3O x and H x radicals generated by the radiolysis of high purity methanol while in water by x OH radical. The degradation in water was increased by 30% than in methanol due the high oxidation potential of x OH while keeping the gamma ray dose constant at 3 kGy. The generated degradation products were identified using GC-MS and their possible transformation pathways are proposed. It is suggested that use of ionization radiations can be an effective and efficient tool for the removal of organophosphate pesticides in waste water.

  4. Effects of nature organic matters and hydrated metal oxides on the anaerobic degradation of lindane,p,p'-DDT and HCB in sediments

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xu; QUAN Xie; ZHAO Hui-min; CHEN Jing-wen; CHEN Shou; ZHAO Ya-zhi

    2003-01-01

    Effects of natural organic matters(NOM) and hydrated metal oxides(HMO) in sediments on the anaerobic degradation of γ-666, p,p'-DDT and HCB were investigated by means of removing NOM and HMO in Liaohe River sediments sequentially. The results showed that the anaerobic degradation of γ-666, p,p'-DDT and HCB followed pseudo-first-order kinetics in different sediments; But, the extents and rates of degradation were different, even the other conditions remained the same. Anaerobic degradation rates of γ-666, p,p'-DDT and HCB were 0.020 d-1, 0.009 d-1 and 0.035 month-1 respectively for the sediments without additional carbon resources. However, with addition of carbon resources, the anaerobic degradation rates of γ-666, p, p'-DDT and HCB were 0.071d-1, 0.054d-1 and 0.088 month-1 in the original sediments respectively. After removing NOM, the rates were decreased to 0.047 d-1, 0.037 d-1 and 0.066 month-1; in the sediments removed NOM and HMO, the rates were increased to 0.067d-1, 0.059 d-1 and 0.086 month-1. These results indicated that NOM in the sediments accelerated the anaerobic degradation of γ-666, p,p'-DDT and HCB; the HMO inhibited the anaerobic degradation of γ-666, p,p'-DDT and HCB.

  5. Chemical composition, anti-oxidative activity and in vitro dry matter degradability of Kinnow mandarin fruit waste

    Directory of Open Access Journals (Sweden)

    Ravleen Kour

    2014-10-01

    Full Text Available Aim: Fruit processing and consumption yield a significant amount of by-products as waste, which can be used as potential nutrient suppliers for livestock. “Kinnow” (Citrus nobilis Lour x Citrus deliciosa Tenora is one of the most important citrus fruit crops of North Indian States. Its residues are rich in carbohydrates but poor in protein and account for approximately 55-60% of the raw weight of the fruit. Present study assessed the chemical composition and anti-oxidative activity of Kinnow mandarin fruit waste (KMW and scrutinized the impact of dietary incorporation of variable levels of KMW on in vitro dry matter digestibility (IVDMD. Materials and Methods: Sun dried and ground KMW was analyzed for proximate composition, fibre fractions and calcium and phosphorus content. Antioxidant potential of KMW as total phenolic count and 1-diphenyl-2-picrylhydrazyl (DPPH scavenging activity was assayed in an alcoholic extract of KMW. The effect of inclusion of KMW at variable levels (0-40% in the isonitrogenous concentrate mixtures on in vitro degradability of composite feed (concentrate mixture:Wheat straw; 40:60 was also carried out. Results: KMW after sun-drying contained 92.05% dry matter. The crude protein content of 7.60% indicates it being marginal in protein content, whereas nitrogen free extract content of 73.69% suggests that it is primarily a carbonaceous feedstuff. This observation was also supported by low neutral detergent fiber and acid detergent fiber content of 26.35% and 19.50%, respectively. High calcium content (0.92% vis-à-vis low phosphorus content (0.08%, resulted in wide Ca:P ratio (11.5 in KMW. High anti-oxidative potential of KMW is indicated by total phenolic content values of 17.1±1.04 mg gallic acid equivalents/g and DPPH free radicle scavenging activity 96.2 μg/ml (effective concentration 50. Mean IVDMD% of all the composite rations was found to be comparable (p>0.05 irrespective of the level of KMW inclusion

  6. Quantifying the effects of sterilization and aging on the oxidative degradation and wear of crosslinked and conventional polyethylene used in total joint replacement

    Science.gov (United States)

    Willie, Bettina Maria

    2005-07-01

    Nearly 500,000 total knee and hip replacements are performed annually in the United States. The generation of ultra-high molecular weight polyethylene (PE) particulate wear debris and associated osteolysis has increasingly become the predominant cause of revision operation. Research has shown that radiation sterilization in air results in increased oxidative degradation and accelerated wear of PE components. The overall goal of this work was to better understand the effect of sterilization, radiation crosslinking, and aging on the oxidative degradation and wear performance of PE components in order to improve clinical outcomes in total joint replacement. The data indicated that after four years of real-time shelf aging, PE that was radiation sterilized in air or nitrogen had significantly greater oxidative degradation compared to PE that was sterilized with either gas plasma or ethylene oxide. After two years of real-time shelf aging, negligible oxidation occurred with minimal changes in density and percent crystallinity, indicating that oxidative degradation was not an issue in the highly crosslinked and conventional polyethylene components examined. The differences measured between time zero and two years shelf aging may be likely explained by instrumentation error or variation within polyethylene manufacturing lots. Data suggest that current manufacturing and packaging technologies have successfully avoided oxidative degradation during shelf aging. Shelf aging may not be a concern in highly crosslinked or conventional polyethylene with current packaging technologies. Conventional PE tibial components had significantly greater percent area of premelt total surface damage compared to crosslinked PE tibial components. However, conventional PE tibial components did not have a significantly different percent area of postmelt total surface damage compared to crosslinked PE tibial components. Data indicated that in vivo duration was a significant predictor of premelt

  7. Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation.

    Science.gov (United States)

    Sygmund, Christoph; Kracher, Daniel; Scheiblbrandner, Stefan; Zahma, Kawah; Felice, Alfons K G; Harreither, Wolfgang; Kittl, Roman; Ludwig, Roland

    2012-09-01

    The genome of Neurospora crassa encodes two different cellobiose dehydrogenases (CDHs) with a sequence identity of only 53%. So far, only CDH IIA, which is induced during growth on cellulose and features a C-terminal carbohydrate binding module (CBM), was detected in the secretome of N. crassa and preliminarily characterized. CDH IIB is not significantly upregulated during growth on cellulosic material and lacks a CBM. Since CDH IIB could not be identified in the secretome, both CDHs were recombinantly produced in Pichia pastoris. With the cytochrome domain-dependent one-electron acceptor cytochrome c, CDH IIA has a narrower and more acidic pH optimum than CDH IIB. Interestingly, the catalytic efficiencies of both CDHs for carbohydrates are rather similar, but CDH IIA exhibits 4- to 5-times-higher apparent catalytic constants (k(cat) and K(m) values) than CDH IIB for most tested carbohydrates. A third major difference is the 65-mV-lower redox potential of the heme b cofactor in the cytochrome domain of CDH IIA than CDH IIB. To study the interaction with a member of the glycoside hydrolase 61 family, the copper-dependent polysaccharide monooxygenase GH61-3 (NCU02916) from N. crassa was expressed in P. pastoris. A pH-dependent electron transfer from both CDHs via their cytochrome domains to GH61-3 was observed. The different properties of CDH IIA and CDH IIB and their effect on interactions with GH61-3 are discussed in regard to the proposed in vivo function of the CDH/GH61 enzyme system in oxidative cellulose hydrolysis. PMID:22729546

  8. Degradation of trans-ferulic acid in acidic aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton.

    Science.gov (United States)

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric

    2016-12-01

    Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton's reaction between cathodically generated H2O2 and added catalytic Fe(2+). The substrate was very slowly removed by AO-H2O2, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with OH in the bulk. The AO-H2O2 process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC-MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization involving all the detected products is finally proposed.

  9. Nitric Oxide Induces Cardiac Protection by Preventing Extracellular Matrix Degradation through the Complex Caveolin-3/EMMPRIN in Cardiac Myocytes.

    Science.gov (United States)

    Cuadrado, Irene; Castejon, Borja; Martin, Ana M; Saura, Marta; Reventun-Torralba, Paula; Zamorano, Jose Luis; Zaragoza, Carlos

    2016-01-01

    Inhibition of Extracellular Matrix degradation by nitric oxide (NO) induces cardiac protection against coronary ischemia/reperfusion (IR). Glycosylation of Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) stimulates enzymatic activation of matrix metalloproteinases (MMPs) in the heart, although the mechanisms leading to EMMPRIN glycosylation are poorly understood. We sought to determine if NO may induce cardiac protection by preventing glycosylation of EMMPRIN in a mouse model of IR. Here we found that Caveolin-3 binds to low glycosylated EMMPRIN (LG-EMMPRIN) in cardiac cells and in the hearts of healthy mice, whereas IR disrupted the complex in nitric oxide synthase 2 (NOS2) knockout (KO) mice. By contrast, the binding was partially restored when mice were fed with an NO donor (DEA-NO) in the drinking water, showing a significant reduction on infarct size (NOS2KO: 34.6±5 vs NOS2KO+DEA-NO: 20.7±9), in expression of matrix metalloproteinases, and cardiac performance was improved (left ventricular ejection fraction (LVEF). NOS2KO: 31±4 vs NOS2KO+DEA-NO: 46±6). The role of Caveolin-3/EMMPRIN in NO-mediated cardiac protection was further assayed in Caveolin-3 KO mice, showing no significant improvement on infarct size (Caveolin-3 KO: 34.8±3 vs Caveolin-3 KO+DEA-NO:33.7±5), or in the expression of MMPs, suggesting that stabilization of the complex Caveolin-3/LG-EMMPRIN may play a significant role in the cardioprotective effect of NO against IR. PMID:27649573

  10. Degradation of graphite in gas cooled reactors due to radiolytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Moskovic, R., E-mail: robert.moskovic@magnoxnorthsites.com

    2014-04-01

    Magnox reactors employ pile grade A (PGA) graphite as a moderator. Reactor cores are constructed typically of twelve to thirteen layers of graphite bricks. Fuel channels (FC) are in the centre of all bricks and interstitial channels (IC) at the centre of the corners of every second set of four bricks. The reactor core is cooled by carbon dioxide, the temperature of graphite core increases from 250 °C at the bottom to 360 °C at the top of the core. The neutron dose increases progressively with the operating time of the reactor. The graphite core looses mass as a result of radiolytic oxidation. The process is dependent on both total energy deposition and temperature which correlates with core height. Fast neutron dose accumulates at the same rate as the total energy deposited and is readily available. The reduction of density of moderator graphite increases the porosity and in turn changes both the physical and mechanical properties of graphite. The mechanical properties and density of graphite are measured either on samples installed in the reactor prior to service or trepanned from graphite bricks. The data obtained on these samples are interrogated using probability modelling to establish trends with increasing service life. Results of the analyses are illustrated in the paper. PGA graphite is an aggregate of coarse needle coke filler particles within a matrix of fine coke flour particles mixed with pitch binder. The bricks are fabricated in the green condition by extrusion of dry calcinated coke impregnated with liquid pitch binder and then graphitized at 2800 °C. This produces a polygranular aggregate with orthotropic properties. The strength properties of graphite are measured using different types of tests. The most commonly used tests involve bending, uniaxial and diametral compression. The initiation and propagation of cracks was investigated to improve understanding of strength behaviour. Cracking was examined on macro-scale using optical microscopy and

  11. In-situ synthesis of nanomagnetites on poly(amidoamine)-modified graphite oxides and their novel catalytic performances towards the degradation of p-nitroaniline

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Hybrids of modified GO and in-situ synthesized magnetite were prepared. • The hybrid performed light-free catalyses on degradation of p-nitroaniline. • Air and aqueous medium were indispensible for the degradation. • The degradation performed fluently without adding H2O2 or pH adjusting. • Such novel properties differed from those of most reported GO hybrids. - Abstract: An approach of loading nanomagnetites (NMs), obtained by in-situ synthesis, on graphite oxides (GO) or poly(amidoamine)-modified GO (pGO) was described in detail in this work. Compared with the GO-NM, the pGO-NM hybrids performed excellent catalysis on degradation of aqueous p-nitroaniline in surrounding air and aqueous medium with a mechanical agitation without light irradiations and additional hydrogen peroxides. These properties differed tremendously from those of most reported metallic oxide-GO hybrids. The catalytic decomposing of the p-nitroaniline was recorded by the successive measurements of an ultraviolet–visible spectrometer. The chemical modifications on GO were investigated with infrared and X-ray photoelectron spectrometers. The hybrids of GO-NM and pGO-NM are estimated with ultraviolet–visible spectrometer, X-ray diffraction, transmission electron microscopy, cyclic voltammetry measurements and thermogravimetric analyses. The experimental results showed that the dissolved oxygen and water were involved in the degradation, which provided solid evidences for the mechanism discussion

  12. In-situ synthesis of nanomagnetites on poly(amidoamine)-modified graphite oxides and their novel catalytic performances towards the degradation of p-nitroaniline

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang, E-mail: liuxiang@ahut.edu.cn; Zhao, Tiantian; Cheng, Heming; Zhu, Chaoqun; Li, Shun; Cui, Ping, E-mail: cokecp@sohu.com

    2015-02-01

    Graphical abstract: - Highlights: • Hybrids of modified GO and in-situ synthesized magnetite were prepared. • The hybrid performed light-free catalyses on degradation of p-nitroaniline. • Air and aqueous medium were indispensible for the degradation. • The degradation performed fluently without adding H{sub 2}O{sub 2} or pH adjusting. • Such novel properties differed from those of most reported GO hybrids. - Abstract: An approach of loading nanomagnetites (NMs), obtained by in-situ synthesis, on graphite oxides (GO) or poly(amidoamine)-modified GO (pGO) was described in detail in this work. Compared with the GO-NM, the pGO-NM hybrids performed excellent catalysis on degradation of aqueous p-nitroaniline in surrounding air and aqueous medium with a mechanical agitation without light irradiations and additional hydrogen peroxides. These properties differed tremendously from those of most reported metallic oxide-GO hybrids. The catalytic decomposing of the p-nitroaniline was recorded by the successive measurements of an ultraviolet–visible spectrometer. The chemical modifications on GO were investigated with infrared and X-ray photoelectron spectrometers. The hybrids of GO-NM and pGO-NM are estimated with ultraviolet–visible spectrometer, X-ray diffraction, transmission electron microscopy, cyclic voltammetry measurements and thermogravimetric analyses. The experimental results showed that the dissolved oxygen and water were involved in the degradation, which provided solid evidences for the mechanism discussion.

  13. Thiocyanate hydrolase, the primary enzyme initiating thiocyanate degradation in the novel obligately chemolithoautotrophic halophilic sulfur-oxidizing bacterium Thiohalophilus thiocyanoxidans.

    Science.gov (United States)

    Bezsudnova, Ekaterina Yu; Sorokin, Dimitry Yu; Tikhonova, Tamara V; Popov, Vladimir O

    2007-12-01

    Thiohalophilus thiocyanoxidans is a first halophilic sulfur-oxidizing chemolithoautotrophic bacterium capable of growth with thiocyanate as an electron donor at salinity up to 4 M NaCl. The cells, grown with thiocyanate, but not with thiosulfate, contained an enzyme complex hydrolyzing thiocyanate to sulfide and ammonia under anaerobic conditions with carbonyl sulfide as an intermediate. Despite the fact of utilization of the , high cyanase activity was also detected in thiocyanate-induced cells. Three-stage column chromotography resulted in a highly purified thiocyanate-hydrolyzing protein with an apparent molecular mass of 140 kDa that consists of three subunits with masses 17, 19 and 29 kDa. The enzyme is a Co,Fe-containing protein resembling on its function and subunit composition the enzyme thiocyanate hydrolase from the Betaproteobacterium Thiobacillus thioparus. Cyanase, copurified with thiocyanate hydrolase, is a bisubstrate multisubunit enzyme with an apparent subunit molecular mass of 14 kDa. A possible role of cyanase in thiocyanate degradation by T. thiocyanoxidans is discussed.

  14. Solid oxide fuel cell anode degradation by the effect of hydrogen chloride in stack and single cell environments

    Science.gov (United States)

    Madi, Hossein; Lanzini, Andrea; Papurello, Davide; Diethelm, Stefan; Ludwig, Christian; Santarelli, Massimo; Van herle, Jan

    2016-09-01

    The poisoning effect by hydrogen chloride (HCl) on state-of-the-art Ni anode-supported solid oxide fuel cells (SOFCs) at 750 °C is evaluated in either hydrogen or syngas fuel. Experiments are performed on single cells and short stacks and HCl concentration in the fuel gas is increased from 1 ppm(v) up to 1000 ppm(v) at different current densities. Characterization methods such as cell voltage monitoring vs. time and electrochemical impedance response analysis (distribution of relaxation times (DRT), equivalent electrical circuit) are used to identify the prevailing degradation mechanism. Single cell experiments revealed that the poisoning is more severe when feeding with hydrogen than with syngas. Performance loss is attributed to the effects of HCl adsorption onto nickel surfaces, which lowered the catalyst activity. Interestingly, in syngas HCl does not affect stack performance even at concentrations up to 500 ppm(v), even when causing severe corrosion of the anode exhaust pipe. Furthermore, post-test analysis suggests that chlorine is present on the nickel particles in the form of adsorbed chlorine, rather than forming a secondary phase of nickel chlorine.

  15. Rare Earth Oxide-Treated Fullerene and Titania Composites with Enhanced Photocatalytic Activity for the Degradation of Methylene Blue

    Institute of Scientific and Technical Information of China (English)

    MENG Zada; ZHU Lei; CHOI Jong-geun; PARK Chong-yeon; OH Won-chun

    2011-01-01

    Rare earth oxide-treated fullerene and titania composites (Y-fullerene/TiO2) were prepared by the sol-gel method.The products had interesting surface compositions.X-ray diffraction patterns of the composites showed that the Y-fullerene/TiO2 composites contained a single and clear anatase phase.The surface properties were observed by scanning electron microscopy,which gave a characterization of the texture on the Y-fullerene/TiO2 composites and showed a homogenous distribution of titanium particles.The energy-dispersive X-ray spectra showed the presence of C and Ti with strong Y peaks.The composite obtained was also characterized with transmission electron microscopy and UV-Vis spectroscopy.The photocatalytic results showed that the y-fullerene/TiO2 composites had excellent activity for the degradation of methylene blue under visible light irradiation.This was attributed to both the effects on the photocatalysis of the supported TiO2 by charge transfer by the fullerene,and the introduction of yttrium to enhance photo-generated electron transfer.

  16. Ozone/graphene oxide catalytic oxidation: a novel method to degrade emerging organic contaminant N, N-diethyl-m-toluamide (DEET).

    Science.gov (United States)

    Liu, Jia-Nan; Chen, Zhuo; Wu, Qian-Yuan; Li, Ang; Hu, Hong-Ying; Yang, Cheng

    2016-01-01

    N, N-diethyl-m-toluamide (DEET) is one of the important emerging contaminants that are being increasingly detected in reclaimed water as well as in drinking water sources. However, DEET is refractory to conventional biological treatment and pure ozone which is absent of hydroxyl radical. Current researches on the efficient removal of DEET are still quite limited. This study utilizes a novel method, namely ozone/graphene oxide (O3/GO), to investigate the effects on DEET removal in aqueous systems, especially in reclaimed water. The results indicate that the DEET degradation rate was significantly accelerated through the combined effect of GO and ozonation which can yield abundant hydroxyl radical, compared to pure ozone condition. According to hydroxyl radical scavenging experiments, hydroxyl radical was found to play a dominant role in synergistic removal of DEET. These findings can offer sound suggestions for future research on the removal of emerging organic contaminants. The information could also be beneficial to reclaimed water safety and sustainable management. PMID:27510858

  17. Ozone/graphene oxide catalytic oxidation: a novel method to degrade emerging organic contaminant N, N-diethyl-m-toluamide (DEET)

    Science.gov (United States)

    Liu, Jia-Nan; Chen, Zhuo; Wu, Qian-Yuan; Li, Ang; Hu, Hong-Ying; Yang, Cheng

    2016-08-01

    N, N-diethyl-m-toluamide (DEET) is one of the important emerging contaminants that are being increasingly detected in reclaimed water as well as in drinking water sources. However, DEET is refractory to conventional biological treatment and pure ozone which is absent of hydroxyl radical. Current researches on the efficient removal of DEET are still quite limited. This study utilizes a novel method, namely ozone/graphene oxide (O3/GO), to investigate the effects on DEET removal in aqueous systems, especially in reclaimed water. The results indicate that the DEET degradation rate was significantly accelerated through the combined effect of GO and ozonation which can yield abundant hydroxyl radical, compared to pure ozone condition. According to hydroxyl radical scavenging experiments, hydroxyl radical was found to play a dominant role in synergistic removal of DEET. These findings can offer sound suggestions for future research on the removal of emerging organic contaminants. The information could also be beneficial to reclaimed water safety and sustainable management.

  18. COMPARATIVE KINETICS STUDY OF THE THERMAL AND THERMO-OXIDATIVE DEGRADATION OF A POLYSTYRENE-CLAY NANOCOMPOZITE BY TGA AND DSC

    Directory of Open Access Journals (Sweden)

    Ion Dranca

    2010-12-01

    Full Text Available The methods of thermogravimetry (TGA and differential scanning calorimetry (DSC have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS and a PS-clay nanocomposite. An advanced isoconversional method has been applied for kinertic analysis. Introduction of the clay phase increasers the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials

  19. Towards a Biocatalyst for (S)-Styrene Oxide Production: Characterization of the Styrene Degradation Pathway of Pseudomonas sp. Strain VLB120

    OpenAIRE

    Panke, Sven; Witholt, Bernard; Schmid, Andreas; Wubbolts, Marcel G.

    1998-01-01

    In order to design a biocatalyst for the production of optically pure styrene oxide, an important building block in organic synthesis, the metabolic pathway and molecular biology of styrene degradation in Pseudomonas sp. strain VLB120 was investigated. A 5.7-kb XhoI fragment, which contained on the same strand of DNA six genes involved in styrene degradation, was isolated from a gene library of this organism in Escherichia coli by screening for indigo formation. T7 RNA polymerase expression e...

  20. Reductive and oxidative degradation of iopamidol, iodinated X-ray contrast media, by Fe(III)-oxalate under UV and visible light treatment.

    Science.gov (United States)

    Zhao, Cen; Arroyo-Mora, Luis E; DeCaprio, Anthony P; Sharma, Virender K; Dionysiou, Dionysios D; O'Shea, Kevin E

    2014-12-15

    Iopamidol, widely employed as iodinated X-ray contrast media (ICM), is readily degraded in a Fe(III)-oxalate photochemical system under UV (350 nm) and visible light (450 nm) irradiation. The degradation is nicely modeled by pseudo first order kinetics. The rates of hydroxyl radical (OH) production for Fe(III)-oxalate/H2O2/UV (350 nm) and Fe(III)-oxalate/H2O2/visible (450 nm) systems were 1.19 ± 0.12 and 0.30 ± 0.01 μM/min, respectively. The steady-state concentration of hydroxyl radical (OH) for the Fe(III)-oxalate/H2O2/UV (350 nm) conditions was 10.88 ± 1.13 × 10(-14) M and 2.7 ± 0.1 × 10(-14) M for the Fe(III)-oxalate/H2O2/visible (450 nm). The rate of superoxide anion radical (O2(-)) production under Fe(III)-oxalate/H2O2/UV (350 nm) was 0.19 ± 0.02 μM/min with a steady-state concentration of 5.43 ± 0.473 × 10(-10) M. Detailed product studies using liquid chromatography coupled to Q-TOF/MS demonstrate both reduction (multiple dehalogenations) and oxidation (aromatic ring and side chains) contribute to the degradation pathways. The reduction processes appear to be initiated by the carbon dioxide anion radical (CO2(-)) while oxidation processes are consistent with OH initiated reaction pathways. Unlike most advanced oxidation processes the Fe(III)-oxalate/H2O2/photochemical system can initiate to both reductive and oxidative degradation processes. The observed reductive dehalogenation is an attractive remediation strategy for halogenated organic compounds as the process can dramatically reduce the formation of the problematic disinfection by-products often associated with oxidative treatment processes. PMID:25269106

  1. Behavioral evidence of the dominant radicals and intermediates involved in Bisphenol A degradation using an efficient Co2+/PMS oxidation process

    International Nuclear Information System (INIS)

    This study investigated the degradation and mineralization of Bisphenol A (BPA) at pH 7, taken as a model compound in the presence of the trace metal-ions, Co2+, and peroxymonosulfate (Oxone: PMS). We took advantage of the high oxidation-reduction potential of hydroxyl and sulfite radicals transformed from PMS as the oxidants to oxidize BPA to less complex compounds (stoichiometric ratio: [PMS]0/[BPA]0 = 2). Afterwards, the expected radicals were used to mineralize those compounds more efficiently (TOC removal ∼40%) as compared to the 1% removal demonstrated in the UV/persulfate system in our previous study. To the best of our knowledge, this is the first attempt to evidence that the dominant behavior of radicals in a (bi)sulfite process is very different from that in a persulfate process. Additionally, the utilization of extremely small amounts of activator and oxidant for the complete degradation of BPA was achieved. The BPA degradation in this Co2+/PMS process formulated a pseudo-first-order kinetic model well over a practicable range of 25-45 oC. The activation energy (ΔE = 57.6 kJ mol-1) was calculated under different conditions, and the detailed discussion indicates that the activity of BPA degradation is not obviously dependent on the PMS concentration, but rather is related to Co2+ dosage. Possible BPA side-chain oxidative metabolic pathways are suggested based on experimental results incorporating the evidence from EPR (electron paramagnetic resonance) and analysis from GC-MS (gas chromatography-mass spectrometry).

  2. Design of a Metal Oxide-Organic Framework (MoOF) Foam Microreactor: Solar-Induced Direct Pollutant Degradation and Hydrogen Generation.

    Science.gov (United States)

    Zhu, Liangliang; Fu Tan, Chuan; Gao, Minmin; Ho, Ghim Wei

    2015-12-16

    A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly. PMID:26501718

  3. Design of a Metal Oxide-Organic Framework (MoOF) Foam Microreactor: Solar-Induced Direct Pollutant Degradation and Hydrogen Generation.

    Science.gov (United States)

    Zhu, Liangliang; Fu Tan, Chuan; Gao, Minmin; Ho, Ghim Wei

    2015-12-16

    A macroporous carbon network combined with mesoporous catalyst immobilization by a template method gives a metal-oxide-organic framework (MoOF) foam microreactor that readily soaks up pollutants and localizes solar energy in itself, leading to effective degradation of water pollutants (e.g., methyl orange (MO) and also hydrogen generation. The cleaned-up water can be removed from the microreactor simply by compression, and the microreactor used repeatedly.

  4. Textile dye degradation by bacterial consortium and subsequent toxicological analysis of dye and dye metabolites using cytotoxicity, genotoxicity and oxidative stress studies.

    Science.gov (United States)

    Phugare, Swapnil S; Kalyani, Dayanand C; Patil, Asmita V; Jadhav, Jyoti P

    2011-02-15

    The present study aims to evaluate Red HE3B degrading potential of developed microbial consortium SDS using two bacterial cultures viz. Providencia sp. SDS (PS) and Pseudomonas aeuroginosa strain BCH (PA) originally isolated from dye contaminated soil. Consortium was found to be much faster for decolorization and degradation of Red HE3B compared to the individual bacterial strain. The intensive metabolic activity of these strains led to 100% decolorization of Red HE3B (50 mg l(-1)) with in 1h. Significant induction of various dye decolorizing enzymes viz. veratryl alcohol oxidase, laccase, azoreductase and DCIP reductase compared to control, point out towards their involvement in overall decolorization and degradation process. Analytical studies like HPLC, FTIR and GC-MS were used to scrutinize the biodegradation process. Toxicological studies before and after microbial treatment was studied with respect to cytotoxicity, genotoxicity, oxidative stress, antioxidant enzyme status, protein oxidation and lipid peroxidation analysis using root cells of Allium cepa. Toxicity analysis with A. cepa signifies that dye Red HE3B exerts oxidative stress and subsequently toxic effect on the root cells where as biodegradation metabolites of the dye are relatively less toxic in nature. Phytotoxicity studies also indicated that microbial treatment favors detoxification of Red HE3B.

  5. Identification of volatile butyl rubber thermal-oxidative degradation products by cryofocusing gas chromatography/mass spectrometry (cryo-GC/MS).

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jonell Nicole; White, Michael Irvin; Bernstein, Robert; Hochrein, James Michael

    2013-02-01

    Chemical structure and physical properties of materials, such as polymers, can be altered as aging progresses, which may result in a material that is ineffective for its envisioned intent. Butyl rubber formulations, starting material, and additives were aged under thermal-oxidative conditions for up to 413 total days at up to 124 ÀC. Samples included: two formulations developed at Kansas City Plant (KCP) (#6 and #10), one commercially available formulation (#21), Laxness bromobutyl 2030 starting material, and two additives (polyethylene AC-617 and Vanax MBM). The low-molecular weight volatile thermal-oxidative degradation products that collected in the headspace over the samples were preconcentrated, separated, and detected using cryofocusing gas chromatography mass spectrometry (cryo-GC/MS). The majority of identified degradation species were alkanes, alkenes, alcohols, ketones, and aldehydes. Observations for Butyl #10 aged in an oxygen-18 enriched atmosphere (18O2) were used to verify when the source of oxygen in the applicable degradation products was from the gaseous environment rather than the polymeric mixture. For comparison purposes, Butyl #10 was also aged under non-oxidative thermal conditions using an argon atmosphere.

  6. Protective effect of curcumin and chlorophyllin against DNA mutation induced by cyclophosphamide or benzo[a]pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, M.A.; Elbehairy, A.M.; Ghoneim, M.A.; Amer, H.A. [Cairo Univ., Giza (Egypt). Biochemistry Dept. and Biotechnology Center

    2007-03-15

    The current study was carried out to evaluate the potency of curcumin and chlorophyllin as natural antioxidants to reduce the oxidative stress markers induced by cyclophosphamide (CP) and benzo[a]pyrene [B(a)P] which were used as free radical inducers. For this purpose, 126 male albino rats were used. The animals were assigned into 4 main groups: negative control group; oxidant-treated group (subdivided into two subgroups: cyclophosphamide- treated group and benzo[a]pyrene-treated group); curcumin-treated group; and chlorophyllin-treated group. Liver samples were collected after two days post the oxidant inoculation and at the end of the experimental period (10 weeks). These samples were examined for determination of liver microsomal malondialdehyde (MDA), DNA fragmentation, restriction fragment length polymorphism (RFLP) and 8-hydroxy deoxyguanosine (8-OHdG) concentration. Both CP and B(a)P caused increments in DNA fragmentation percentages, liver microsomal MDA, concentration of 8-OHdG and induced point mutation. Treatment of rats with either curcumin or chlorophyllin revealed lower DNA fragmentation percentages, liver microsomal MDA concentration, concentration of 8-OHdG and prevented induction of mutations, i. e., reversed the oxidative stress induced by CP and B(a)P and proved that they were capable of protecting rats against the oxidative damage evoked by these oxidants. (orig.)

  7. Mechanism of azo dye degradation in Advanced Oxidation Processes: Degradation of Sulfanilic Acid Azochromotrop and its parent compounds in aqueous solution by ionizing radiation

    Science.gov (United States)

    Pálfi, Tamás; Wojnárovits, László; Takács, Erzsébet

    2011-03-01

    Mechanistic studies were made on hydroxyl radical and hydrated electron reaction with Sulfanilic Acid Azochromotrop (SPADNS) as model azo dye in dilute aqueous solution. SPADNS contains 4,5-dihydroxynaphthalene-2,7-disulfonic acid part and 4-sulfophenylazo group. To establish the details of the reaction mechanism the reactions of two simpler molecules without 4-sulfophenylazo part were also studied: one of them contained one (in position 4, II), the other two (in positions 4 and 5, III) -OH groups. Hydroxyl radicals react with these molecules with radical addition to the naphthalene-2,7-disulfonic acid part. The adduct hydroxycyclohexadienyl type radical decays in radical-radical reactions, or undergoes a (pH dependent) water elimination to yield naphthoxy radical. The radical decay takes place on the ms timescale. Degradation efficiencies are 0.6-0.8. Hydrated electron in the case of the two simpler molecules reacts with the rings, while in the case of dye with the azo bond. Electron scavenging is followed by protonation, this reaction in the case of II and III yields cyclohexadienyl, while with the dye hydrazo radical. The efficiency of degradation with II and III is 0.2-0.6, while for SPADNS it is close to 1.

  8. Mechanism of azo dye degradation in Advanced Oxidation Processes: Degradation of Sulfanilic Acid Azochromotrop and its parent compounds in aqueous solution by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Palfi, Tamas; Wojnarovits, Laszlo [Institute of Isotopes, Hungarian Academy of Sciences, H-1525 Budapest, P.B. 77 (Hungary); Takacs, Erzsebet, E-mail: takacs@iki.kfki.h [Institute of Isotopes, Hungarian Academy of Sciences, H-1525 Budapest, P.B. 77 (Hungary)

    2011-03-15

    Mechanistic studies were made on hydroxyl radical and hydrated electron reaction with Sulfanilic Acid Azochromotrop (SPADNS) as model azo dye in dilute aqueous solution. SPADNS contains 4,5-dihydroxynaphthalene-2,7-disulfonic acid part and 4-sulfophenylazo group. To establish the details of the reaction mechanism the reactions of two simpler molecules without 4-sulfophenylazo part were also studied: one of them contained one (in position 4, II), the other two (in positions 4 and 5, III) -OH groups. Hydroxyl radicals react with these molecules with radical addition to the naphthalene-2,7-disulfonic acid part. The adduct hydroxycyclohexadienyl type radical decays in radical-radical reactions, or undergoes a (pH dependent) water elimination to yield naphthoxy radical. The radical decay takes place on the ms timescale. Degradation efficiencies are 0.6-0.8. Hydrated electron in the case of the two simpler molecules reacts with the rings, while in the case of dye with the azo bond. Electron scavenging is followed by protonation, this reaction in the case of II and III yields cyclohexadienyl, while with the dye hydrazo radical. The efficiency of degradation with II and III is 0.2-0.6, while for SPADNS it is close to 1.

  9. Effects of benzo(a)pyrene exposure on the antioxidant enzyme activity of scallop Chlamys farreri

    Science.gov (United States)

    Pan, Luqing; Ren, Jiayun; Zheng, Debin

    2009-02-01

    Scallop Chlamys farreri was exposed to different concentrations of benzo(a)pyrene (BaP) (0.5 μg/L, 1.0 μg/L, 10.0 μg/L and 50.0 μg/L) for 30 days in seawater. The 7-ethoxyresorufin O-deethylase (EROD) activity was significantly induced, and increased with the increasing BaP concentration. The glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx) activities increased in short time at low concentration of BaP, and was significantly depressed at high concentrations. Scallop gill was more sensitive to BaP than the digestive gland, and the digestive gland was the main tissue to deal with oxyradicals. The contents of malondialdehyde (MDA) increased with the exposure time and there was a positive correlation (concentration-effect) between the MDA content and the concentration of BaP. The biomarkers determined in this experiment had important roles in detoxification, and showed great potential as biomarkers for oxidative stress. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

  10. Effects of benzo(a)pyrene exposure on the antioxidant enzyme activity of scallop Chlamys farreri

    Institute of Scientific and Technical Information of China (English)

    PAN Luqing; REN Jiayun; ZHENG Debin

    2009-01-01

    Scallop Chlamys farreri was exposed to different concentrations of benzo(a)pyrene (BaP) (0.5 μg/L, 1.0 μg/L, 10.0 μg/L and 50.0 μg/L) for 30 days in seawater. The 7-ethoxyresorufin O-deethylase (EROD) activity was significantly induced, and increased with the increasing BaP concentration. The glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx) activities increased in short time at low concentration of BaP, and was significantly depressed at high concentrations. Scallop gill was more sensitive to BaP than the digestive gland, and the digestive gland was the main tissue to deal with oxyradicals. The contents of malondialdehyde (MDA) increased with the exposure time and there was a positive correlation (concentration-effect) between the MDA content and the concentration of BaP. The biomarkers determined in this experiment had important roles in detoxification, and showed great potential as biomarkers for oxidative stress. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment.

  11. Nanocrystalline ZnO doped lanthanide oxide: An efficient photocatalyst for the degradation of malachite green dye under visible light irradiation

    Directory of Open Access Journals (Sweden)

    G.A. Suganya Josephine

    2015-09-01

    Full Text Available Visible light induced semiconductor photocatalysis has received a great attention in recent years due to the contamination of water bodies. In the present study, we have reported the photo catalytic degradation of a toxic organic dye, malachite green using a ZnO doped Dy2O3 photo catalyst under visible light irradiation. The nanocrystalline photocatalyst was prepared by a precipitation method employing the respective nitrates and sodium carbonate as precursors and were characterized by FT-IR, XRD, UV–Vis DRS, FE-SEM and AFM analysis. The experimental results proved that the prepared photo catalysts were crystalline, nanosized and highly active in the visible region. UV–Vis DRS results suggested that the band gap was 3.1 eV for the prepared photo catalyst. The photodegradation efficiency of malachite green was analysed by various experimental parameters namely pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV–Visible spectrophotometer. The degradation of malachite green was above 99% within 1 h of visible light irradiation employing the doped photocatalyst, whereas pristine metal oxide possessed only 67% and pristine lanthanide oxide possessed activity which was only due to photolysis. A plausible mechanism for the generation of OH radicals and the pathway for MG dye degradation has been proposed in this study. The experimental results clearly show that nanocrystalline semiconductor doped lanthanide oxides are highly active under visible light irradiations and may find wider applications in environmental remediation technologies.

  12. Impact of hydrodynamics on pollutant degradation and energy efficiency of VUV/UV and H2O2/UV oxidation processes.

    Science.gov (United States)

    Bagheri, Mehdi; Mohseni, Madjid

    2015-12-01

    The Vacuum-UV/UV process, an incipient catalyst/chemical-free advanced oxidation process (AOP), is potentially a cost-effective solution for the removal of harmful micropollutants from water. Utilizing a novel mechanistic numerical model, this work aimed to establish a thorough understanding of the degradation mechanisms in the VUV/UV process operating under continuous flow conditions, when compared with the widely applied H2O2/UV AOP. Of particular interest was the examination of the impact of flow characteristics (hydrodynamics) on the degradation efficacy of a target micropollutant during the VUV/UV and H2O2/UV AOPs. While hydroxyl radical (OH) oxidation was the dominant degradation pathway in both processes, the degradation efficacy of the VUV/UV process showed much stronger correlation with the extent of mixing in the photoreactor. Under a uniform flow regime, the degradation efficiency of the target pollutant achieved by the H2O2/UV process with 2- and 5 ppm H2O2 was greater than that provided by the VUV/UV process. Nonetheless, introduction of mixing and circulation zones to the VUV/UV reactor resulted in superior performance compared with the H2O2/UV AOP. Based on the electrical energy-per-order (EEO) analysis, incorporation of circulation zones resulted in a reduction of up to 50% in the overall energy cost of the VUV/UV AOP, while the corresponding reduction for the 5-ppm H2O2/UV system was less than 5%. Furthermore, the extent of OH scavenging of natural organic matter (NOM) on energy efficiency of the VUV/UV and H2O2/UV AOPs under continuous flow conditions was assessed using the EEO analysis. PMID:26363258

  13. Impact of hydrodynamics on pollutant degradation and energy efficiency of VUV/UV and H2O2/UV oxidation processes.

    Science.gov (United States)

    Bagheri, Mehdi; Mohseni, Madjid

    2015-12-01

    The Vacuum-UV/UV process, an incipient catalyst/chemical-free advanced oxidation process (AOP), is potentially a cost-effective solution for the removal of harmful micropollutants from water. Utilizing a novel mechanistic numerical model, this work aimed to establish a thorough understanding of the degradation mechanisms in the VUV/UV process operating under continuous flow conditions, when compared with the widely applied H2O2/UV AOP. Of particular interest was the examination of the impact of flow characteristics (hydrodynamics) on the degradation efficacy of a target micropollutant during the VUV/UV and H2O2/UV AOPs. While hydroxyl radical (OH) oxidation was the dominant degradation pathway in both processes, the degradation efficacy of the VUV/UV process showed much stronger correlation with the extent of mixing in the photoreactor. Under a uniform flow regime, the degradation efficiency of the target pollutant achieved by the H2O2/UV process with 2- and 5 ppm H2O2 was greater than that provided by the VUV/UV process. Nonetheless, introduction of mixing and circulation zones to the VUV/UV reactor resulted in superior performance compared with the H2O2/UV AOP. Based on the electrical energy-per-order (EEO) analysis, incorporation of circulation zones resulted in a reduction of up to 50% in the overall energy cost of the VUV/UV AOP, while the corresponding reduction for the 5-ppm H2O2/UV system was less than 5%. Furthermore, the extent of OH scavenging of natural organic matter (NOM) on energy efficiency of the VUV/UV and H2O2/UV AOPs under continuous flow conditions was assessed using the EEO analysis.

  14. Toxicokinetic of benzo[a]pyrene and fipronil in female green frogs (Pelophylax kl. esculentus)

    International Nuclear Information System (INIS)

    A general consensus that an increased logKow led to an increase in xenobiotic uptake and bioaccumulation is accepted. In this study we compared the toxicokinetics of two chemically different xenobiotics, i.e. benzo[a]pyrene and fipronil in female green frogs. Surprisingly, the uptake rates and the bioconcentration factors (BCF) of the two contaminants were not predicted by their logKow. The uptake rates obtained were of the same order of magnitude for the two contaminants and the BCFs measured for fipronil were about 3-fold higher than those obtained for benzo[a]pyrene. Fipronil appeared to be more recalcitrant than benzo[a]pyrene to detoxification processes leading to the accumulation of sulfone-fipronil especially in the ovaries. This phenomenon may explain reproductive influence of this contaminant described in other studies. Detoxification processes, including metabolism and the excretion of pollutants, are of importance when considering their persistence in aquatic organisms and trying to quantify their risks. Highlights: ► The uptake of benzo[a]pyrene is 1.5–3 times higher than for fipronil. ► Fipronil was more recalcitrant than benzo[a]pyrene to detoxification processes. ► This lead to increased-bioaccumulation factors except in excretion organs. ► Amphibians can be used as biomonitors for persistent pollutants. - Fipronil is more recalcitrant than benzo[a]pyrene to detoxification processes in frog.

  15. Thermal Oxidation of Polyolefins by Mild Pro-Oxidant Additives Based on Iron Carboxylates and Lipophilic Amines: Degradability in the Absence of Light and Effect on the Adhesion to Paperboard

    Directory of Open Access Journals (Sweden)

    Tuan-Anh Nguyen

    2015-08-01

    Full Text Available Marine and inland pollution by non-degradable plastic bags and other plastic articles is a topic of great concern. Natural degradation processes based on oxidation of plastic pollutants could possibly contribute to limit the extent of pollution. Thermal degradation of polyolefins in the absence of light by non-polluting pro-oxidants has not been presented before. In this study, we show that two amines, stearyl amine and [(3-(11-aminoundecanoyl amino propane-1-] silsesquioxane (amino-POSS in combination with ferric stearate (FeSt3 tremendously accelerate the thermal oxidation of polyolefins compared with reference samples. Both amines and FeSt3 are to a large extent based on renewable resources. Polyethylene and polypropylene samples containing less than 100 ppm of iron and 1% of amine were extremely brittle after 10 days in a circulation oven in the absence of light. No significant degradation could be seen with samples containing iron but no amine. In a different application, the initial oxidation of polyethylene can be used in order to increase its adhesion to cardboard. Excellent adhesion between polyethylene and cardboard is important for liquid packaging based on renewable resources. Amino-POSS has been chosen for food packaging applications due to its expected lower leakage from polyethylene (PE compared with stearyl amine. Film samples of PE/amino-POSS/FeSt3 blends were partly oxidized in a circulation oven. The oxidation was documented by increased carbonyl index (CI and melt flow index (MFI. The limited extent of oxidation has been proved by unchanged tensile strength and only moderate changes in elongation at break when compared to reference polyethylene films containing no FeSt3 or amino-POSS. The PE/amino-POSS/FeSt3 blends were compression moulded to paperboard. The adhesion of non-aged blends to paperboard decreased with increasing amino-POSS content which is in good compliance with an earlier reported lubricant effect of high

  16. Mitochondrial DNA damage and dysfunction, and oxidative stress are associated with endoplasmic reticulum stress, protein degradation and apoptosis in high fat diet-induced insulin resistance mice.

    Directory of Open Access Journals (Sweden)

    Larysa V Yuzefovych

    Full Text Available BACKGROUND: Recent studies showed a link between a high fat diet (HFD-induced obesity and lipid accumulation in non-adipose tissues, such as skeletal muscle and liver, and insulin resistance (IR. Although the mechanisms responsible for IR in those tissues are different, oxidative stress and mitochondrial dysfunction have been implicated in the disease process. We tested the hypothesis that HFD induced mitochondrial DNA (mtDNA damage and that this damage is associated with mitochondrial dysfunction, oxidative stress, and induction of markers of endoplasmic reticulum (ER stress, protein degradation and apoptosis in skeletal muscle and liver in a mouse model of obesity-induced IR. METHODOLOGY/PRINCIPAL FINDINGS: C57BL/6J male mice were fed either a HFD (60% fat or normal chow (NC (10% fat for 16 weeks. We found that HFD-induced IR correlated with increased mtDNA damage, mitochondrial dysfunction and markers of oxidative stress in skeletal muscle and liver. Also, a HFD causes a change in the expression level of DNA repair enzymes in both nuclei and mitochondria in skeletal muscle and liver. Furthermore, a HFD leads to activation of ER stress, protein degradation and apoptosis in skeletal muscle and liver, and significantly reduced the content of two major proteins involved in insulin signaling, Akt and IRS-1 in skeletal muscle, and Akt in liver. Basal p-Akt level was not significantly influenced by HFD feeding in skeletal muscle and liver. CONCLUSIONS/SIGNIFICANCE: This study provides new evidence that HFD-induced mtDNA damage correlates with mitochondrial dysfunction and increased oxidative stress in skeletal muscle and liver, which is associated with the induction of markers of ER stress, protein degradation and apoptosis.

  17. Assessment by HPLC of the degradation behavior of acitretin under hydrolytic, oxidative, photolytic and thermal stress conditions

    Directory of Open Access Journals (Sweden)

    Pawan K. Porwal

    2014-12-01

    Full Text Available Acitretin is a photosensitive oral retinoid with very limited data available on its degradation. The official HPLC method for acitretin determination was insufficient to resolve the degradation products generated during stability studies. Therefore, an isocratic RP-HPLC–UV method was developed for the determination of acitretin in the presence of its related impurities and degradation products. Efficient chromatographic separation was achieved on a Thermo beta-basic column C18 (100 mm×4.6 mm, 5 μm with mobile phase containing 0.3% (v/v glacial acetic acid with acetonitrile (ACN and isopropyl alcohol (IPA in an isocratic ratio of 70:30 at a flow rate of 1.0 mL/min with the eluent monitored at 360 nm. The method was validated for specificity, linearity, precision, accuracy and robustness. The calibration plot was linear over the concentration range of 50–150 μg/mL with a correlation coefficient (r2 of 0.999. The proposed method was used to investigate the degradation kinetics of acitretin under the different degradative conditions. The degradation rate constant (K, half-life (t1/2, and t90 were calculated. Degradation of acitretin followed pseudo-first-order kinetics. The drug was found to be less stable under acidic and photolytic degradation conditions: the photolytic degradation constants for acitretin in sunlight and UV light were 0.002698% and 0.0008402% min−1, respectively. The LOD for acitretin and the known impurities were at a level below 0.02%. The method shows consistent recoveries for ACTR (99.8%–101.2% and also for its known impurities (97.2–101.3%. The method was found to be accurate, precise, linear, specific, sensitive, rugged, robust, and useful for characterizing the stability of this chemical.

  18. The use HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS for rapid analysis of degradation by oxidation and sonication of an azo dye

    OpenAIRE

    Djelal, Hayet; Cornée, Carole; Tardivel, Ronan; Lavastre, Olivier; Amrane, Abdelatif

    2013-01-01

    Advanced oxidation processes are efficient for the removal of recalcitrant compounds, like azo-dyes. However, the intermediates produced during their degradation can be more toxic than the parent compounds. Improving the knowledge concerning the degradation pathways may be therefore helpful to optimize the process. In this aim, HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS were considered and applied to analyze the sono-oxidation of an azo dye, methyl red sodi...

  19. Degradation of polyethylene induced by plasma in oxidizing atmospheres; Degradacion de polietileno inducido por plasma en atmosferas oxidantes

    Energy Technology Data Exchange (ETDEWEB)

    Colin, E.; Olayo, M.G.; Cruz, G.J. [Facultad de Quimica, UAEM, Av. Tollocan y Colon, 50000 Toluca (Mexico)

    2002-07-01

    The garbage of polyethylene is not easily degradable in normal environmental conditions . The indiscriminate use of this polymer and the enormous quantity of garbage which is generated carries a damage to the environment due to its long life as waste. The objective of this work is to study the conditions in which can be carried out the degradation of polyethylene. A form of accelerating the degradation is exposing it to plasma with reactive atmospheres. In this work a study of surface modification of polyethylene by plasmas with discharges of direct current of oxygen and nitrogen is presented. (Author)

  20. Oxidative degradation of 2,4-dioxohexahydro-1,3,5-triazine in aqueous medium: a radiation and photochemical study

    International Nuclear Information System (INIS)

    The kinetics and spectral nature of the intermediates resulting from the reaction of OH with 2,4-dioxohexahydro-1,3,5-triazine (DHT) have been studied by pulse radiolysis. The degradation leading to a complete disappearance of DHT induced by OH in aqueous medium was also studied using steady state radiolysis technique. The rate constant, determined by competitive kinetic methods, was 1.6 x 109 dm3 mol-1 s-1 at pH 6. The complete degradation in N2O was observed with an absorbed dose of 7 kGy. The complete degradation in presence of ferricperchlorate using UV light was observed within 6 minute. (author)

  1. Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

    DEFF Research Database (Denmark)

    Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng;

    2013-01-01

    degradation in terms of weight loss and molecular weight decrease. The presence of phosphoric acid as an inevitable dopant of the membranes, on the other hand, significantly impeded the membrane degradation by means of metal ion complexing, decreased pH, and acid–base interactions with the amino groups....... In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer...... of the polymer. Fuel cell durability tests with contaminations of ferrous ions did show considerable performance degradation, however, primarily due to the catalyst deterioration rather than the membrane degradation....

  2. In vitro degradation and biocompatibility of a strontium-containing micro-arc oxidation coating on the biodegradable ZK60 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xiao [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Yang, Xiaoming [Panyu Hospital of Chinese Medicine, 65 Qiaodong Road, Guangzhou 511400 (China); Tan, Lili, E-mail: lltan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li, Mei [Hospital of Orthopedics, Guangzhou General Hospital of Guangzhou Military Command, 111 Liuhua Road, Guangzhou 510010 (China); Wang, Xin [College of Chemistry, Liaoning University, 66 Chongshanzhong Road, Shenyang 110036 (China); Zhang, Yu, E-mail: luck_2001@126.com [Hospital of Orthopedics, Guangzhou General Hospital of Guangzhou Military Command, 111 Liuhua Road, Guangzhou 510010 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Hu, Zhuangqi [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Qiu, Jianhong [Trauson Medical Instrument Co., Ltd., Changzhou 213163 (China)

    2014-01-01

    Magnesium alloys are promising biodegradable implant candidates for orthopedic application. In the present study, a phosphate-based micro-arc oxidation (MAO) coating was applied on the ZK60 alloy to decrease its initial degradation rate. Strontium (Sr) was incorporated into the coating in order to improve the bioactivity of the coating. The in vitro degradation studies showed that the MAO coating containing Sr owned a better initial corrosion resistance, which was mainly attributed to the superior inner barrier layer, and a better long-term protective ability, probably owning to its larger thickness, superior inner barrier layer and the superior apatite formation ability. The degradation of MAO coating was accompanied by the formation of degradation layer and Ca-P deposition layer. The in vitro cell tests demonstrated that the incorporation of Sr into the MAO coating enhanced both the proliferation of preosteoblast cells and the alkaline phosphatase activity of the murine bone marrow stromal cells. In conclusion, the MAO coating with Sr is a promising surface treatment for the biodegradable magnesium alloys.

  3. Degradation of alpha-pinene oxide and [2H7]-2,5,6-trimethyl-hept-(2E)-enoic acid by Pseudomonas fluorescens NCIMB 11761.

    Science.gov (United States)

    Zorn, H; Neuser, F; Berger, R G

    2004-02-01

    When submerged cultured Pseudomonas fluorescens NCIMB 11761 was fed-batch supplemented with alpha-pinene oxide, a rapid formation of 2,6-dimethyl-5-methylene-hept-(2Z)-enal (I) (isonovalal) was observed. Biotransformation and isomerisation of (I) to the (2E)-isomer (II) (novalal) were enhanced by Lewatit OC 1064, a macroporous polystyrene adsorbent. Accelerated isomerisation in the presence of an amino donor (glycine) at pH 7.3 pointed to a merely chemical mechanism. A maximum yield of 48 g of aldehydesl(-1) was achieved, but quantitative analysis of the volatile fraction showed that the molar conversion of the pinene oxide substrate reached no more than 67%. To fill this gap of the mass balance, the acidic fraction was isolated. It contained several compounds which suggested a beta-oxidation-like catabolism starting from 2,6-dimethyl-5-methylene-hept-(2E)-enoic acid (III) (novalic acid). Using [2H7]-2,5,6-dimethyl-hept-(2E)-enoic acid as a conversion substrate and gas chromatography coupled to atomic emission detection and mass spectrometry a degradation pathway via labelled 3,4-dimethylpentenoic and methylpropanoic acids was evidenced. This pathway may play a predominant role in isoprenoid degradation by soil bacteria.

  4. Degradation of the electrical characteristics of MOS structures with erbium, gadolinium, and dysprosium oxides under the effect of an electric field

    International Nuclear Information System (INIS)

    The degradation of the characteristics of silicon metal-oxide-semiconductor (MOS) structures with oxides of rare-earth elements under the effect of electric fields with intensities of 0.1–4 MV/cm during the course of electroforming is studied. A specific feature of electroforming consists in the possibility of multiple switching of the structures from the insulating state to the low-resistivity one and back. The temporal characteristics of the degradation of MOS structures during the course of electroforming are exponential. The current-voltage characteristics follow the power law in the range of 0.2–3 V; the effect of an electric field brings about a variation in the distribution of the energy density of traps responsible for currents limited by space charge. It is established that multiple cycles of electroforming lead to an increase in the density of surface states at the Si-oxide interface and to a variation in the energy position of the trap levels, which affects the charge state of the traps

  5. Degradation of H-acid in aqueous solution by microwave assisted wet air oxidation using Ni-loaded GAC as catalyst

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yao-bin; QUAN Xie; ZHAO Hui-min; CHEN Shuo; YANG Feng-lin

    2005-01-01

    A novel process, microwave assisted catalytic wet air oxidation(MW-CWO), was applied for the degradation of H-acid( 1-amino8-naphthol-3, 6-disulfonic acid) in aqueous solution. Ni-loaded granular activated carbon (GAG), prepared by immersion-calcination method, was used as catalyst. The results showed that the MW-CWO process was very effective for the degradation of H-acid in aqueous solution under atmospheric pressure with 87.4% TOC (total organic carbon) reduction in 20 min. Ni on GAC existed in the form of NiO as specified by XRD. Loss of Ni was significant in the initial stage, and then remained almost constant after 20 min reaction. BET surface area results showed that the surface property of GAC after MW-CWO process was superior to that of blank GAC.

  6. Effect of phosphate additives on the microstructure, bioactivity, and degradability of microarc oxidation coatings on Mg-Zn-Ca-Mn alloy.

    Science.gov (United States)

    Dou, Jinhe; You, Qiongya; Gu, Guochao; Chen, Chuanzhong; Zhang, Xihua

    2016-01-01

    Calcium phosphate coatings were prepared on the surface of self-designed Mg-Zn-Ca-Mn alloy using microarc oxidization technology. To characterize the microstructures, cross-section morphologies, and compositions of the coatings, the authors used scanning electron microscopy equipped with an energy-disperse spectrometer, x-ray diffraction, and Fourier transform infrared spectroscopy. Potentiodynamic polarization in the simulated body fluid (SBF) was used to evaluate the corrosion behaviors of the samples. An SBF immersion test was used to evaluate the coating bioactivity and degradability. After the immersion tests, some bonelike apatite formed on the coating surfaces indicate that bioactivity of the coatings is excellent. The coating prepared in electrolyte containing (NaPO3)6 had slower degradation rate after immersion test for 21 days. PMID:27440396

  7. An integrated (electro- and bio-oxidation) approach for remediation of industrial wastewater containing azo-dyes: Understanding the degradation mechanism and toxicity assessment.

    Science.gov (United States)

    Aravind, Priyadharshini; Selvaraj, Hosimin; Ferro, Sergio; Sundaram, Maruthamuthu

    2016-11-15

    A hybrid approach for the remediation of recalcitrant dye wastewater is proposed. The chlorine-mediated electrochemical oxidation of real textile effluents and synthetic samples (using Ti/IrO2-RuO2-TiO2 anodes), lead to discoloration by 92% and 89%, respectively, in 100min, without significant mineralization. The remediation was obtained through biodegradation, after removing the residual bio-toxic active chlorine species via sunlight exposition. Results show that the electrochemical discoloration enhances the effluent biodegradability with about 90% COD removal employing acclimatized naphthalene-degrading bacterial consortia, within 144h. Based on results obtained through FT-IR and GC-MS, it is likely that azo group stripping and oxidative cleavage of dyes occur due to the nucleophilic attack of active chlorine species during electro-oxidation. This leads to generation of aromatic intermediates which are further desulfonated, deaminated or oxidized only at their functional groups. These aromatic intermediates were mineralized into simpler organic acids and aldehydes by bacterial consortia. Phyto-toxicity trials on Vigna radiata confirmed the toxic nature of the untreated dye solutions. An increase in root and shoot development was observed with the electrochemically treated solutions, the same was higher in case of bio-treated solutions. Overall, obtained results confirm the capability of the proposed hybrid oxidation scheme for the remediation of textile wastewater. PMID:27427887

  8. Effect of ageing on benzo[a]pyrene extractability in contrasting soils

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Luchun [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Naidu, Ravi, E-mail: Ravi.Naidu@newcastle.edu.au [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Liu, Yanju; Palanisami, Thavamani; Dong, Zhaomin; Mallavarapu, Megharaj [CERAR-Centre for Environmental Risk Assessment and Remediation and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Semple, Kirk T. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2015-10-15

    Highlights: • In vitro assessment of B[a]P in contaminated soils using 4 different methods. • An exponential kinetic model fits well with the extractability data. • Fitting parameter and {sup 14}C residue correlates with key soil properties. • Fractionation of B[a]P was obtained based on extractability by extractants. - Abstract: Changes in benzo[a]pyrene (B[a]P) extractability over 160 days ageing in four contrasting soils varying in organic matter content and clay mineralogy were investigated using dichloromethane: acetone 1:1 (DCM/Ace), 60 mM hydroxypropyl-β-cyclodextrin (HPCD) solution, 1-butanol (BuOH) and Milli-Q water. The B[a]P extractability by the four methods decreased with ageing and a first-order exponential model could be used to describe the kinetics of release. Correlation of the kinetic rate constant with major soil properties showed a significant effect of clay and sand contents and pore volume fraction (<6 nm) on sequestration of the desorbable fraction (by HPCD) and the water-extractable fraction. Analysis of {sup 14}C-B[a]P in soils after ageing showed a limited loss of B[a]P via degradation. Fractionation of B[a]P pools associated with the soil matrix was analysed according to extractability of B[a]P by the different extraction methods. A summary of the different fractions is proposed for the illustration of the effect of ageing on different B[a]P-bound fractions in soils. This study provides a better understanding of the B[a]P ageing process associated with different fractions and also emphasises the extraction capacity of the different methods employed.

  9. [Benzo(a)pyrene contamination of vegetable oils].

    Science.gov (United States)

    Jedra, Małgorzata; Starski, Andrzej; Gawarska, Halina; Sawilska-Rautenstrauch, Dorota

    2008-01-01

    Benzo(a)pyrene (B(a)P) analysis was carried out with glass chromatographic column with alumina followed by reverse phase high-performance liquid chromatography (HPLC) and spectrofluorometric detection. B(a)P level in 40 vegetable oils were as follow: from 0.11 to 0.38 microg/kg in olive; from 0.92 to 3.74 microg/kg in rape seed oils; from 0.11 to 2.25 microg/kg in sunflower oils and from 0.33 to 1.26 microg/kg in soya oils. In another investigated oils: arachide (peanut) corn, safflower, linen, hempen, sesame, pumpkin seeds, grape seeds---values from 0.10 to 1.44 microg/kg and 3.83 microg/kg in sea buckthorn oil were detected. B(a)P concentration in 4 from 40 investigated oils exceed the 2 ppb limit proposed by the European Commission. Heating of sample of oils: olive, rape, soya, linen, corn, sesame, peanut, in temp. 240 degrees C for 30 min. has not influence on decreased of B(a)P level. PMID:18807910

  10. Semi-empirical study of ortho-cresol photo degradation in manganese-doped zinc oxide nanoparticles suspensions

    Directory of Open Access Journals (Sweden)

    Abdollahi Yadollah

    2012-08-01

    Full Text Available Abstract The optimization processes of photo degradation are complicated and expensive when it is performed with traditional methods such as one variable at a time. In this research, the condition of ortho-cresol (o-cresol photo degradation was optimized by using a semi empirical method. First of all, the experiments were designed with four effective factors including irradiation time, pH, photo catalyst’s amount, o-cresol concentration and photo degradation % as response by response surface methodology (RSM. The RSM used central composite design (CCD method consists of 30 runs to obtain the actual responses. The actual responses were fitted with the second order algebraic polynomial equation to select a model (suggested model. The suggested model was validated by a few numbers of excellent statistical evidences in analysis of variance (ANOVA. The used evidences include high F-value (143.12, very low P-value (2 = 0.99 and the adequate precision (47.067. To visualize the optimum, the validated model simulated the condition of variables and response (photo degradation % be using a few number of three dimensional plots (3D. To confirm the model, the optimums were performed in laboratory. The results of performed experiments were quite close to the predicted values. In conclusion, the study indicated that the model is successful to simulate the optimum condition of o-cresol photo degradation under visible-light irradiation by manganese doped ZnO nanoparticles.

  11. Origin of degradation phenomenon under drain bias stress for oxide thin film transistors using IGZO and IGO channel layers.

    Science.gov (United States)

    Bak, Jun Yong; Kang, Youngho; Yang, Shinhyuk; Ryu, Ho-Jun; Hwang, Chi-Sun; Han, Seungwu; Yoon, Sung-Min

    2015-01-20

    Top-gate structured thin film transistors (TFTs) using In-Ga-Zn-O (IGZO) and In-Ga-O (IGO) channel compositions were investigated to reveal a feasible origin for degradation phenomenon under drain bias stress (DBS). DBS-driven instability in terms of V(TH) shift, deviation of the SS value, and increase in the on-state current were detected only for the IGZO-TFT, in contrast to the IGO-TFT, which did not demonstrate V(TH) shift. These behaviors were visually confirmed via nanoscale transmission electron microscopy and energy-dispersive x-ray spectroscopy observations. To understand the degradation mechanism, we performed ab initio molecular dynamic simulations on the liquid phases of IGZO and IGO. The diffusivities of Ga and In atoms were enhanced in IGZO, confirming the degradation mechanism to be increased atomic diffusion.

  12. ZnO/MoO 3 mixed oxide nanotube: A highly efficient and stable catalyst for degradation of dye by air under room conditions

    Science.gov (United States)

    Huang, Jiguo; Wang, Xiaohong; Li, Sen; Wang, Yu

    2010-10-01

    As a continuation of our work to develop catalysts with high activity for catalytic air wet oxidation process under mild conditions, degradation of wastewater containing 0.3 g/L Safranin-T (ST) by air oxidation over ZnO/MoO 3 nanotube catalyst was studied. It was found the decolorization efficiency and the chemical oxygen demand (COD) removal of ST reached above 98% and 95%, respectively, within 18 min at room temperature and atmospheric pressure. And the organic pollutants were totally mineralized to simple inorganic species such as HCO 3-, Cl - and NO 3-, while the total organic carbon (TOC) decreased 99.3%. The structure and morphology of the catalyst after ten cycling runs showed that the catalyst was stable under such operating condition and the leaching test showed negligible leaching effect. This ZnO/MoO 3 nanotube is proved to be an active and stable heterogeneous catalyst in CWAO of ST under extremely mild conditions.

  13. Effects of fungal degradation on the CuO oxidation products of lignin: A controlled laboratory study

    Science.gov (United States)

    Hedges, John I.; Blanchette, Robert A.; Weliky, Karen; Devol, Allan H.

    1988-11-01

    Duplicate samples of birch wood were degraded for 0, 4, 8 and 12 weeks by the white-rot fungus, Phlebia tremellosus, and for 12 weeks by 6 other white-rot and brown-rot fungi. P. tremellosus caused progressive weight losses and increased the H/C and O/C of the remnant wood by preferentially degrading the lignin component of the middle lamellae. This fungus increased the absolute (weight loss-corrected) yield of the vanillic acid CuO reaction product above its initial level and exponentially decreased the absolute yields of all other lignin-derived phenols. Total yields of syringyl phenols were decreased 1.5 times as fast as total vanillyl phenol yields. Within both phenol families, aldehyde precursors were degraded faster than precursors of the corresponding ketones, which were obtained in constant proportion to the total phenol yield. Although two other white-rot fungi caused similar lignin compositional trends, a fourth white-rot species, Coriolus versicolor, simultaneously eroded all cell wall components and did not concentrate polysaccharides in the remnant wood. Wood degraded by the three brown-rot fungi exhibited porous cell walls with greatly reduced integrity. The brown-rot fungi also preferentially attacked syringyl structural units, but degraded all phenol precursors at a much slower rate than the white-rotters and did not produce excess vanillic acid. Degradation by P. tremellosus linearly increased the vanillic acid/vanillin ratio, (Ad/Al)v, of the remnant birch wood throughout the 12 week degradation study and exponentially decreased the absolute yields of total vanillyl phenols, total syringyl phenols and the syringyl/vanillyl phenol ratio, S/V. At the highest (Ad/Al)v of 0.50 (12 week samples), total yields of syringyl and vanillyl phenols were decreased by 65% and 80%, respectively, with a resulting reduction of 40% in the original S/V. Many of the diagenetically related compositional trends that have been previously reported for lignins in natural

  14. 铋银氧化物混合物高效氧化降解四溴双酚 A的研究%Efficient Oxidative Degradation of Tetrabromobisphenol A by Silver Bism uth Oxide

    Institute of Scientific and Technical Information of China (English)

    陈满堂; 宋洲; 王楠; 丁耀彬; 廖海星; 朱丽华

    2015-01-01

    以AgNO3和NaBiO3•2H2O为原料,采用离子交换-共沉淀法制备了铋银氧化物混合物(silver bismuth oxide,BSO),并利用它氧化降解溴代阻燃剂四溴双酚A( TBBPA)。研究了制备过程中银铋摩尔比及降解过程中BSO用量对TBBPA降解效果的影响。结果表明,当银铋摩尔比为1:1,BSO用量为1 g•L-1时,40 mg•L-1 TBBPA在7 min内可完全降解,其总有机碳的去除率高达80%。采用离子色谱﹑气相色谱-质谱联用仪及X射线光电子能谱监测降解过程中TBBPA的变化,发现TBBPA降解过程涉及脱溴﹑叔丁基碳的断裂和苯环的开环氧化等反应。利用NaN3作为分子探针,发现单线态氧是BSO氧化降解TBBPA的主要反应活性物种。%Silver bismuth oxide(BSO)was prepared by a simple ion exchange-coprecipitation method with AgNO3 and NaBiO3•2H2O as raw materials, and then used to oxidatively degrade tetrabromobisphenol A( TBBPA) . Effects of the molar ratio of Ag/Bi during BSO preparation and the BSO dosage on the degradation of TBBPA were investigated. The results showed that under the optimized conditions (i. e. , the Ag/Bi molar ratio of 1:1, BSO dosage of 1 g•L-1), 40 mg•L-1 of TBBPA was completely degraded and the removal of total organic carbon achieved more than 80% within 7 min. The degradation intermediates of TBBPA were identified by ion chromatography, gas chromatograph-mass spectrometer and X-ray photoelectron spectroscopy. The degradation pathway of TBBPA included the debromination, the cleavage of tert-butyl group and the open epoxidation of benzene ring. Based on a quenching study of NaN3 , singlet oxygen was proved to play a dominant role in the TBBPA degradation.

  15. Increased photocatalytic activity of Zn(II)/Cu(II) oxides and sulfides by coupling and supporting them onto clinoptilolite nanoparticles in the degradation of benzophenone aqueous solution.

    Science.gov (United States)

    Esmaili-Hafshejani, Javad; Nezamzadeh-Ejhieh, Alireza

    2016-10-01

    Photocatalytic activity of the coupled ZnO-CuO and ZnS-CuS semiconductors supported onto clinoptilolite nanoparticles (CNP) and micronized one (CMP) was studied in photodegradation of benzophenone (BP) aqueous solution. The ZnO-CuO/CNP (or MCP) and ZnS-CuS/CNP (or MCP) catalysts were prepared via calcination and sulfiding of their Zn(II)-Cu(II) ion-exchanged samples, respectively. XRD patterns confirmed loading of the mentioned semiconductors onto the zeolite, and nano dimension of the catalysts was confirmed by XRD and TEM results. Typical Tauc plots obtained from UV-vis DRS spectra showed red shifts for the band gap energies of the supported coupled semiconductors with respect to the supported monocomponent ones especially for ZnO/NCP and ZnS/NCP catalysts. Also, in both indirect and direct transitions, these red shifts were more considerable in the oxidic systems with respect to the sulfidic systems. Accordingly, the supported oxidic systems showed better photocatalytic activity than the sulfidic one. In the oxidic systems changing the dose of CuO played important role while in the sulfidic systems ZnS played considerable role in the degradation of BP. In the used systems, CuO and ZnS played the main e/h generators in the oxidic and sulfidic systems, respectively, while ZnO and CuS played the preventer e/h recombination. Based on the results, production of e/h is the rate limiting step in the used systems. The maximum degradation activity of the catalysts was obtained at: 0.12gL(-1) of ZnO0.80-CuO3.18/NCP and 0.10gL(-1) of ZnS1.39-CuS2.88/NCP catalysts, initial BP concentration of 30mgL(-1) at pH 7.5.

  16. Photocatalytic degradation of acid blue 74 in water using Ag-Ag2O-Zno nanostuctures anchored on graphene oxide

    Science.gov (United States)

    Umukoro, Eseoghene H.; Peleyeju, Moses G.; Ngila, Jane C.; Arotiba, Omotayo A.

    2016-01-01

    Water pollution due to industrial effluents from industries which utilize dyes in the manufacturing of their products has serious implications on aquatic lives and the general environment. Thus, there is need for the removal of dyes from wastewater before being discharged into the environment. In this study, a nanocomposite consisting of silver, silver oxide (Ag2O), zinc oxide (ZnO) and graphene oxide (GO) was synthesized, characterized and photocatalytically applied in the degradation (and possibly mineralization) of organic pollutants in water treatment process. The Ag-Ag2O-ZnO nanostructure was synthesized by a co-precipitation method and calcined at 400 °C. It was functionalized using 3-aminopropyl triethoxysilane and further anchored on carboxylated graphene oxide via the formation of an amide bond to give the Ag-Ag2O-ZnO/GO nanocomposite. The prepared nanocomposite was characterized by UV-Vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transformed infrared spectroscopy (FTIR), and Raman spectroscopy. The applicability of Ag-Ag2O-ZnO/GO nanocomposite as a photocatalyst was investigated in the photocatalytic degradation of acid blue 74 dye under visible light irradiation in synthetic wastewater containing the dye. The results indicated that Ag-Ag2O-ZnO/GO nanocomposite has a higher photocatalytic activity (90% removal) compared to Ag-Ag2O-ZnO (85% removal) and ZnO (75% removal) respectively and thus lends itself to application in water treatment, where the removal of organics is very important.

  17. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    Science.gov (United States)

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents.

  18. TAML/H2O2 Oxidative Degradation of Metaldehyde: Pursuing Better Water Treatment for the Most Persistent Pollutants.

    Science.gov (United States)

    Tang, Liang L; DeNardo, Matthew A; Gayathri, Chakicherla; Gil, Roberto R; Kanda, Rakesh; Collins, Terrence J

    2016-05-17

    The extremely persistent molluscicide, metaldehyde, widely used on farms and gardens, is often detected in drinking water sources of various countries at concentrations of regulatory concern. Metaldehyde contamination restricts treatment options. Conventional technologies for remediating dilute organics in drinking water, activated carbon, and ozone, are insufficiently effective against metaldehyde. Some treatment plants have resorted to effective, but more costly UV/H2O2. Here we have examined if TAML/H2O2 can decompose metaldehyde under laboratory conditions to guide development of a better real world option. TAML/H2O2 slowly degrades metaldehyde to acetaldehyde and acetic acid. Nuclear magnetic resonance spectroscopy ((1)H NMR) was used to monitor the degradation-the technique requires a high metaldehyde concentration (60 ppm). Within the pH range of 6.5-9, the reaction rate is greatest at pH 7. Under optimum conditions, one aliquot of TAML 1a (400 nM) catalyzed 5% degradation over 10 h with a turnover number of 40. Five sequential TAML aliquots (2 μM overall) effected a 31% removal over 60 h. TAML/H2O2 degraded metaldehyde steadily over many hours, highlighting an important long-service property. The observation of metaldehyde decomposition under mild conditions provides a further indication that TAML catalysis holds promise for advancing water treatment. These results have turned our attention to more aggressive TAML activators in development, which we expect will advance the observed technical performance. PMID:27088657

  19. 电化学氧化降解苯胺的研究%On the degradation of aniline by way of electrochemical oxidation

    Institute of Scientific and Technical Information of China (English)

    褚衍洋; 高珂; 张家臣; 杨国龙

    2011-01-01

    以Ti/SnO2 - Sb2O5为阳极,石墨为阴极研究了苯胺的电化学氧化降解.在阳极氧化的基础上,通过外加Fe2+实现了阳极氧化与电Fenton氧化协同降解苯胺.结果表明,不存在Fe2+时,中性介质和高阳极电位有利于提高苯胺去除率.苯胺被阳极氧化降解的同时,-0.65 V和酸性介质条件下石墨阴极具有良好的还原O2生成H2O2的性能.在pH=3.0和-0.65 V阴极电位条件下,电化学反应600min,H2O2的累计质量浓度达到110 mg·L-1.引入Fe2+后,苯胺降解效果和电流效率得到大幅度提高.在阴极电位为-0.65 V,pH值为3.0,初始Fe2浓度为0.50 mmol· L-的条件下,处理180 mg·L-1苯胺水溶液(Na2SO4为支持电解质)600 min,苯胺去除率达100%,COD去除率为78%.因此,使用恰当的电极材料,控制合理的电极电位,可以实现双极电化学氧化降解水中有机物,并且获得较高的电流效率.%The present work intends to introduce its research results on the degradation of aniline by way of electrochemical oxidation while taking Ti/SnO2 - Sb2O5 electrode as anode and graphite electrode as cathode. Actually, what we have done is just in accord with the ever increasing research trend in the application of electrochemical oxidation technology for the organic pollutants degradation in industrial sewage. The results of our experiments show that a neutral medium and a high anodic potential is beneficial for the aniline removal by anodic oxidation in the absence of Fe2+ . In the course of aniline degradation by anodic oxidation, the graphite cathode behaves itself perfectly in generating H2O2 via the reduction of O2 at the presence of - 0.65 V and acid medium. When the initial pH of the solution was 3.0 and the constant cathodic potential was - 0.65 V, it was possible to make the concentration of H2O2 reach 110 mg·L-1 by the electrochemical reaction of 600 min, which presented an important base for the electro-Fenton oxidation. Besides, though the anodic

  20. The oxidative degradation of polystyrene resins on the removal of Cr(VI) from wastewater by anion exchange.

    Science.gov (United States)

    Xiao, Ke; Xu, Fuyuan; Jiang, Linhua; Dan, Zhigang; Duan, Ning

    2016-08-01

    Cr(VI) is a powerful oxidant and is capable of oxidizing most of the organic materials. Therefore, it is possible for Cr(VI) to oxidize the polymeric resins and change the sorption properties of the resins on the removal of Cr(VI) from wastewater by anion exchange. In this study, three polystyrene resins (D201, D202, and D301) with different functional groups (-N(+)(CH3)3, -N(+)(CH3)2(C2H4OH), and N(CH3)2) were assessed on oxidation stability for Cr(VI) removal from wastewater in fixed-bed column experiments. After a 10-cycle operation, due to the oxidation of the resin, the sorption capacity of D201, D202, and D301 resins decreased by 23.5, 29.3, and 17.3%, when approximately 20-34%, 31-50%, and 18-30% of Cr(VI) was reduced to Cr(III) during each cycle respectively. The results of the Fourier transform infrared spectroscopy (FT-IR) showed that both the cleavage of CN and the formation of CO bonds occurred on the polystyrene resins during the Cr(VI) removal process. The resin simulation experiments further validated the oxidation of CC and CN bonds connected with phenethyl groups. Based upon the results from column operations and the resin simulated experiments, the oxidation mechanism of the polystyrene resin was proposed.

  1. Enhanced photocatalytic activity of degrading short chain chlorinated paraffins over reduced graphene oxide/CoFe2O4/Ag nanocomposite.

    Science.gov (United States)

    Chen, Xin; Zhao, Qidong; Li, Xinyong; Wang, Dong

    2016-10-01

    Short chain chlorinated paraffins have recently attracted great attention because of their environmental persistence and biological toxicity as an important organic pollutant. In this work, reduced graphene oxide/CoFe2O4/Ag (RGO/CoFe2O4/Ag) nanocomposite was prepared and employed for photocatalytic degradation of short chain chlorinated paraffins. The process of photocatalytic degradation of short chain chlorinated paraffins over RGO/CoFe2O4/Ag under visible light (λ>400nm) was investigated by in situ Fourier transform infrared spectroscopy and the related mechanisms were proposed. An apparent degradation ratio of 91.9% over RGO/CoFe2O4/Ag could be obtained under visible light illumination of 12h, while only about 21.7% was obtained with commercial P25 TiO2 under the same experimental conditions, which demonstrates that the RGO/CoFe2O4/Ag nanocomposite is a potential candidate for effective photocatalytic removal of short chain chlorinated paraffins. PMID:27376973

  2. Photocatalytic Degradation of Rhodamine B by Cuprous Oxide%氧化亚铜光催化降解罗丹明 B

    Institute of Scientific and Technical Information of China (English)

    黄涛; 吕重安; 杨水金

    2014-01-01

    Cuprous oxide ( Cu2 O) was successfully prepared by the method of reduction in aqueous at room temperature.All the powders were characterized by X -rays diffraction ( XRD) and scanning electron microscopy ( SEM) .The effect of different factors on the degradation was investigated .The best reaction conditions were found out.The photocatalytic degradation of rhodamine B by Cu 2 O under simulated natural light irradiation was investiga-ted.The results demonstrated that initial concentration of rhodamine B is 10 mg/L, catalyst dosage is 0.38 g/L and the pH is 5.2, the degradation ratio of rhodamine B is as high as 96.5%after 30 minutes simulated natural light ir-radiation .%利用室温液相还原法制备了氧化亚铜,通过XRD、 SEM对其进行了表征,探讨了该催化剂对罗丹明B的光催化降解的活性。在催化剂用量为0.38 g/L,过氧化氢量为1.8 mL,罗丹明B的浓度为10 mg/L, pH为5.2的条件下,光照30 min后罗丹明B的降解率为96.5%。

  3. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO{sub 4} composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yan [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Sun, Shaofang [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Song, Yang; Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Guan, Weisheng [School of Environmental Science and Engineering, Chang’an University, Yanta Road 126, Xi’an, 710054 (China); Liu, Xinlin [School of Material Science and Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Xuefu Road 301, Zhenjiang, 212013 (China)

    2013-04-15

    Highlights: ► Microwave-assisted in situ growth of RGO-BiVO{sub 4} composite was proposed. ► A relatively small particle size with organic-additives free. ► Graphene was formed during the microwave-heating by oxygen capture. ► GB-2 sample exhibits the highest CIP degradation ratio (3 times over pure BiVO{sub 4}). ► The enhancements of activities result from the effective charge separation. -- Abstract: To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO{sub 4} composite photocatalysts. The as-produced RGO-BiVO{sub 4} composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO{sub 4} photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO{sub 4} composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO{sub 4} particles. The enhancement of photocatalytic activities of RGO-BiVO{sub 4} photocatalysts can be attributed to the effective separation of electron–hole pairs rather than the improvement of light absorption.

  4. Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

    International Nuclear Information System (INIS)

    Highlights: ► Microwave-assisted in situ growth of RGO-BiVO4 composite was proposed. ► A relatively small particle size with organic-additives free. ► Graphene was formed during the microwave-heating by oxygen capture. ► GB-2 sample exhibits the highest CIP degradation ratio (3 times over pure BiVO4). ► The enhancements of activities result from the effective charge separation. -- Abstract: To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron–hole pairs rather than the improvement of light absorption

  5. High catalytic activity of magnetic CuFe2O4/graphene oxide composite for the degradation of organic dyes under visible light irradiation

    Science.gov (United States)

    Chen, Peng; Xing, Xiang; Xie, Huifang; Sheng, Qi; Qu, Hongxia

    2016-09-01

    Magnetic CuFe2O4/graphene oxide composite (CuFe2O4/GO) has been synthesized by hydrothermal method and showed excellent visible-light-photocatalytic activity for the degradation of different dyes as Rhodamine B (RhB) and acid orange II (AO7) with no need of H2O2. The Structure and morphology were investigated by XRD, FTIR and TEM and the performance of the catalyst was systematically investigated under various experimental conditions as pH, the dosage of catalyst, dye initial concentration, etc. The dyes degradation on CuFe2O4/GO was also remained in a level in the presence of OH2- radical scavenger (2-propanol), while it decreased in the presence of O2- radical scavenger (benzoquinone) and h+ radical scavenger (ammonium oxalate), indicating that O2- and h+ radicals were responsible for the dye degradation. The magnetic CuFe2O4/GO composite shows potential applications in organic dye water treatment due to its magnetically recyclability and powerful visible-light-photocatalytic activity.

  6. (0 0 1) Facet-exposed anatase-phase TiO2 nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    Science.gov (United States)

    Zhou, Xun; Shi, Tiejun; Wu, Jing; Zhou, Haiou

    2013-12-01

    Reduced graphene oxide (RGO) and TiO2 nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO2 powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by Csbnd Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO2 powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  7. (0 0 1) Facet-exposed anatase-phase TiO{sub 2} nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xun [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Shi, Tiejun, E-mail: stjhfut@163.com [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Wu, Jing [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Zhou, Haiou [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); School of Materials and Chemical Engineering of Anhui University of Architecture, Hefei 230901 (China)

    2013-12-15

    Reduced graphene oxide (RGO) and TiO{sub 2} nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO{sub 2} powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by C-Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO{sub 2} powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  8. Use of solar advanced oxidation processes for wastewater treatment : follow-up on degradation products, acute toxicity, genotoxicity and estrogenicity

    OpenAIRE

    Brienza, M.; Ahmed, M.M; Escande, A; Plantard, G.; Scrano, L.; Chiron, Serge; Bufo, S. A.; Goetz, V.

    2016-01-01

    Wastewater tertiary treatment by advanced oxidation processes is thought to produce a treated effluent with lower toxicity than the initial influent. Here we performed tertiary treatment of a secondary effluent collected from a Waste Water Treatment Plant via homogeneous (solar/HSO5-/Fe2+) and heterogeneous (solar/TiO2) solar advanced oxidation aiming at the assessment of their effectiveness in terms of contaminants' and toxicity abatement in a plain solar reactor. A total of 53 organic conta...

  9. Oxidative modifications, mitochondrial dysfunction, and impaired protein degradation in Parkinson's disease: how neurons are lost in the Bermuda triangle

    OpenAIRE

    Malkus Kristen A; Tsika Elpida; Ischiropoulos Harry

    2009-01-01

    Abstract While numerous hypotheses have been proposed to explain the molecular mechanisms underlying the pathogenesis of neurodegenerative diseases, the theory of oxidative stress has received considerable support. Although many correlations have been established and encouraging evidence has been obtained, conclusive proof of causation for the oxidative stress hypothesis is lacking and potential cures have not emerged. Therefore it is likely that other factors, possibly in coordination with o...

  10. Synthesis and characterization of electroactive films based on benzo(a)pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Michal; Yu Kai [Process Chemistry Centre, c/o Laboratory of Analytical Chemistry, Abo Akademi University, Biskopsgatan 8, FI-20500 Abo/Turku (Finland); Kvarnstroem, Carita, E-mail: carita.kvarnstrom@utu.f [Turku University Centre for Materials and Surfaces, c/o Laboratory of Materials Chemistry and Chemical Analysis, Department of Chemistry, University of Turku, Vatselankatu 2, FI-20014 Turku (Finland); Ivaska, Ari, E-mail: ari.ivaska@abo.f [Process Chemistry Centre, c/o Laboratory of Analytical Chemistry, Abo Akademi University, Biskopsgatan 8, FI-20500 Abo/Turku (Finland)

    2011-04-01

    The polycyclic aromatic hydrocarbons (PAHs) are a group of compounds that might have practical applications due to their graphene-like properties. Derivatized PAHs can self-assemble in liquid crystal form. The chemical synthesis of large size PAHs can however be complicated and problematic. Electrochemical synthesis of PAHs molecules was studied in this work by cyclic voltammetry. Benzo(a)pyrene was used as the monomer. The resulting electroactive films consist of different PAHs in both size and symmetry. We call this mixture poly(benzopyrene) (PBP). The synthesis conditions of PBP were optimized to obtain thick and electrochemically stable films. The best film quality was achieved by potential scanning in propylene carbonate at low scan rate resulting in continues polymer growth during 10 scans giving approx. a 1 {mu}m thick PBP film. During p- and n-doping studies the reduction and oxidation peaks were observed at 1.0 V and -1.6 V, respectively, with an electrochemical band gap of approx. 2.6 eV. The in situ UV-vis characterization of the PBP films was made by applying a constant potential with increasing steps. The optical band gap was approx. 2.5 eV and the absorption maximum was observed at ca. 420 nm. During p- and n-doping new induced bands were formed in the range 575-600 nm. UV-vis spectroscopy indicate that PBP mainly consist of units consisting of more than 40 carbon atoms and large number of {pi}-electrons.

  11. Study of degradation of trace benzene in water by 185 nm UV light and oxidation technique%185nm紫外光/氧化协同降解水体中微量苯的研究

    Institute of Scientific and Technical Information of China (English)

    陆军; 朱承驻

    2011-01-01

    The degradation of trace benzene in water was studied by using 185 nm UV light and oxidation technique. The influence of concentration of benzene, degradation time, pH value of solution, and oxidants on the degradation of benzene was investigated. The degradation products were analyzed by using GC/MS method and the degradation mechanism was presented. The results showed that the trace benzene was effectively degradated by 185 nm UV light and oxidation technique, and after treating for 3 min, the degradation efficiency of CODCr in benzene solution reached above 95% when K2S2O8 was added.%文章利用185 nm紫外光/氧化协同降解技术对水体中微量苯的降解情况进行了研究,考察了溶液中苯的质量浓度、光解时间、溶液pH值以及加入氧化剂等对苯降解的影响,对光解产物进行了分析,并对其降解机理进行了探讨.研究结果表明,该技术能有效降解水体中微量苯,处理3 min时加入K2SO8的苯溶液的CODcr的去除率可达到95%以上.

  12. Bacterial Degradation of Aromatic Compounds

    Directory of Open Access Journals (Sweden)

    Qing X. Li

    2009-01-01

    Full Text Available Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons (PAHs and heterocyclic aromatics. Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups. Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds. Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

  13. Microstructure degradation of cermet anodes for solid oxide fuel cells: Quantification of nickel grain growth in dry and in humid atmospheres

    Science.gov (United States)

    Holzer, L.; Iwanschitz, B.; Hocker, Th.; Münch, B.; Prestat, M.; Wiedenmann, D.; Vogt, U.; Holtappels, P.; Sfeir, J.; Mai, A.; Graule, Th.

    The effects of compositional and environmental parameters on the kinetics of microstructural degradation are investigated for porous Ni/CGO anodes in solid oxide fuel cells (SOFC). Improved methodologies of SEM-imaging, segmentation and object recognition are described which enable a precise quantification of nickel grain growth over time. Due to these methodological improvements the grain growth can be described precisely with a standard deviation of only 5-15 nm for each time step. In humid atmosphere (60 vol.% H 2O, 40% N 2/H 2) the growth rates of nickel are very high (up to 140%/100 h) during the initial period (1000 h) the growth rates decrease significantly to nearly 0%/100 h. In contrast, under dry conditions (97 vol.% N 2, 3 vol.% H 2) the growth rates during the initial period are much lower (ca. 1%/100 h) but they do not decrease over a period of 2000 h. In addition to the humidity factor there are other environmental and compositional parameters which have a strong influence on the kinetics of the microstructural degradation. The nickel coarsening is strongly depending on the gas flow rate. Also the initial microstructures and the anode compositions have a big effect on the degradation kinetics. Thereby small average grain sizes, wide distribution of particle size and high contents of nickel lead to higher coarsening and degradation rates. Whereas the nickel coarsening appears to be the dominant degradation mechanism during the initial period (1000 h) in humidified gas. Thereby the evaporation of volatile nickel species may lead to a local increase of the Ni/CGO ratio. Due to the surface wetting of CGO a continuous layer tends to form on the surface of the nickel grains which prevents further grain growth and evaporation of nickel. These phenomena lead to a microstructural reorganization between 1000 and 2300 h of exposure. This complex pattern of degradation phenomena also leads to a change of the amount of active microstructural sites that are

  14. Study of oil diesel degradation in soil using oxidative advanced processes; Estudo da degradacao do oleo diesel em solo utilizando processos oxidativos avancados

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Suenia S.; Silva, Valdinete L. da; Motta, Mauricio da [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Quimica; Silva, Paula Tereza de S. e; Barros Neto, Benicio de [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Quimica Fundamental

    2004-07-01

    Recently it comes if observing several accidents during the exploration, refinement, transport and operation of storage of petroleum and yours derived, such as the diesel oil and the gasoline. In this paper We do a study of the degradation of the diesel oil in a characteristic soil of the state of Pernambuco using peroxide of hydrogen and Fenton reagent. Those two processes are based on the generation of the radical hydroxyl (OH.) that has to can oxidizer loud capable to promote the destruction of recalcitrant organic compositions. The studied soil has about 16,5{+-}0,3 g/kg of total organic carbon. A factorial planning was accomplished 2{sup 3} with 2 repetitions in the central point with the objective of finding the best conditions of degradation of the pollutant. The variables and the studied levels were: FeSO{sub 4} - 0,18 M (0, 4 and 8 Ml); pH (3; without adjustment and without adjustment) and Time of exhibition in the sun (8; 12 and 16:00). The volumes of H{sub 2}O{sub 2} used in the rehearsals were constant, being 80 mL. Soon afterwards it accomplished a fractional experimental planning 2{sup 3-1}, repeating the variables of the first planning, they put using a smaller volume of H{sub 2}O{sub 2}, 40 mL, to evaluate the influence of the amount of H{sub 2}O{sub 2} used about the degradation of the diesel oil. The mass of the soil used in each experiment was of 5 g. It was observed that there were not significant differences in the degradation in relation to the peroxide volume. The best found degradation was around 87% in the following conditions (4 mL of Faith, without pH adjustment, Time of exhibition in the sun of 12:00 and 80 ml of H{sub 2}O{sub 2}). That found degradation was quite satisfactory being still due to study more economical conditions. (author)

  15. Catalyzed oxidative degradation of methyl orange over Au catalyst prepared by ionic liquid-polymer modified silica

    Science.gov (United States)

    Wang, Y.; Guo, J. S.

    2015-07-01

    A new type of hybrid material was prepared by grafting an ionic liquid monomer, 1-(p-vinylbenzyl)-3-methylimidazolium chloride, on the surface of the porous silica which was synthesized via sodium silicate hydrolysis. The as-synthesized products were characterized by scanning electron microscope, nitrogen physisorption experiment, thermogravimetric analysis and Fourier transform infrared spectra. A catalyst with Au was prepared using the hybrid material as carrier. The experimental results show that the catalyst exhibits a better catalytic effect of hydrogen peroxide on the degradation of methyl orange. The reason may be that the metal component of the catalyst facilitated the dissociation of hydrogen peroxide to produce abundant highly active free radicals which can rapidly ruin the structure of methyl orange molecules in water. Finally, a probable catalytic degradation mechanism based on diffusion was discussed.

  16. Topological, functional, and dynamic properties of the protein interaction networks rewired by benzo(a)pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Ba, Qian [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Li, Junyang; Huang, Chao [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Li, Jingquan; Chu, Ruiai [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Wu, Yongning, E-mail: wuyongning@cfsa.net.cn [Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); Wang, Hui, E-mail: huiwang@sibs.ac.cn [Key Laboratory of Food Safety Research, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Key Laboratory of Food Safety Risk Assessment, Ministry of Health, Beijing (China); School of Life Science and Technology, ShanghaiTech University, Shanghai (China)

    2015-03-01

    Benzo(a)pyrene is a common environmental and foodborne pollutant that has been identified as a human carcinogen. Although the carcinogenicity of benzo(a)pyrene has been extensively reported, its precise molecular mechanisms and the influence on system-level protein networks are not well understood. To investigate the system-level influence of benzo(a)pyrene on protein interactions and regulatory networks, a benzo(a)pyrene-rewired protein interaction network was constructed based on 769 key proteins derived from more than 500 literature reports. The protein interaction network rewired by benzo(a)pyrene was a scale-free, highly-connected biological system. Ten modules were identified, and 25 signaling pathways were enriched, most of which belong to the human diseases category, especially cancer and infectious disease. In addition, two lung-specific and two liver-specific pathways were identified. Three pathways were specific in short and medium-term networks (< 48 h), and five pathways were enriched only in the medium-term network (6 h–48 h). Finally, the expression of linker genes in the network was validated by Western blotting. These findings establish the overall, tissue- and time-specific benzo(a)pyrene-rewired protein interaction networks and provide insights into the biological effects and molecular mechanisms of action of benzo(a)pyrene. - Highlights: • Benzo(a)pyrene induced scale-free, highly-connected protein interaction networks. • 25 signaling pathways were enriched through modular analysis. • Tissue- and time-specific pathways were identified.

  17. Topological, functional, and dynamic properties of the protein interaction networks rewired by benzo(a)pyrene

    International Nuclear Information System (INIS)

    Benzo(a)pyrene is a common environmental and foodborne pollutant that has been identified as a human carcinogen. Although the carcinogenicity of benzo(a)pyrene has been extensively reported, its precise molecular mechanisms and the influence on system-level protein networks are not well understood. To investigate the system-level influence of benzo(a)pyrene on protein interactions and regulatory networks, a benzo(a)pyrene-rewired protein interaction network was constructed based on 769 key proteins derived from more than 500 literature reports. The protein interaction network rewired by benzo(a)pyrene was a scale-free, highly-connected biological system. Ten modules were identified, and 25 signaling pathways were enriched, most of which belong to the human diseases category, especially cancer and infectious disease. In addition, two lung-specific and two liver-specific pathways were identified. Three pathways were specific in short and medium-term networks (< 48 h), and five pathways were enriched only in the medium-term network (6 h–48 h). Finally, the expression of linker genes in the network was validated by Western blotting. These findings establish the overall, tissue- and time-specific benzo(a)pyrene-rewired protein interaction networks and provide insights into the biological effects and molecular mechanisms of action of benzo(a)pyrene. - Highlights: • Benzo(a)pyrene induced scale-free, highly-connected protein interaction networks. • 25 signaling pathways were enriched through modular analysis. • Tissue- and time-specific pathways were identified

  18. Differential degradation of intact polar and core glycerol dialkyl glycerol tetraether lipids upon post-depositional oxidation

    OpenAIRE

    Lengger, S. K.; Kraaij, M.; Tjallingii, R.; Baas, M.; Stuut, J.-B.; Hopmans, E.C.; Sinninghe Damsté, J.S.; Schouten, S.

    2013-01-01

    Archaeal and bacterial glycerol dialkyl glycerol tetraether lipids (GDGTs) are used in various proxies, such as TEX86 and the BIT index. In living organism, they contain polar head groups (intact polar lipids – IPLs). IPL GDGTs have also been detected in ancient marine sediments and it is unclear whether or not they are fossil entities or are part of living cells. In order to determine the extent of degradation of IPL GDGTs over geological timescales, we analyzed turbidite deposits, which had...

  19. Synthesis and application of green mixed-metal oxide nano-composite materials from solid waste for dye degradation.

    Science.gov (United States)

    Singh, Seema; Srivastava, Vimal Chandra; Mandal, Tapas Kumar; Mall, Indra Deo; Lo, Shang Lien

    2016-10-01

    Present study demonstrates reutilization of electrochemical (EC) sludge as a potential low-cost green catalyst for dye degradation. Hexagonal Fe2O3 type phase with trevorite (NiFe2O4)-type cubic phase nanocomposite material (NCM) was synthesized from solid waste sludge generated during EC treatment of textile industry wastewater with stainless steel electrode. For NCM synthesis, sludge was heated at different temperatures under controlled condition. Various synthesized NCMs were characterized by powder X-ray diffraction (PXD), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. The synthesized NCMs were found to contain iron, chromium, nickel and oxygen in the form of α-Fe2O3 (metal: oxygen = 40:60), (Fe,Cr,Ni)2O3 and trevorite NiFe2O4, (Ni,Fe,Cr) (Fe,Cr,Ni)2O4 (metal: oxygen = 43:57). Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), pore size distribution, and atomic force microscope (AFM) analysis showed distribution of grains of different shapes and sizes. Catalytic activity of NCM was studied by the methylene red dye degradation by using the catalytic wet peroxidation process. Zeta potential study was performed under different pH so as to determine the performance of the NCMs during dye degradation. PMID:27341375

  20. Kinetics study of metaxalone degradation under hydrolytic, oxidative and thermal stress conditions using stability- indicating HPLC method

    Institute of Scientific and Technical Information of China (English)

    Vamsi Krishna Marothu; Rajendra N. Dash; Saritha Vemula; Shravani Donkena; Ramesh Devi; Madhavi Gorrepati

    2012-01-01

    An isocratic stability indicating RP-HPLC-UV method is presented for the determina- tion of metaxalone (MET) in the presence of its degradation products. The method uses Dr. Maisch C18 column (250 mm × 4.6 mm, 5μm) with mobile phase consisting of acetonitrile-potassium dihydrogen orthophosphate buffer with 4 mL of 0.4% triethyl amine (pH 3.0; 10 mM) (58:42, v/v) at a flow rate of 1.0 mL/min, pH of the buffer was adjusted with o-phosphoric acid. UV detection was performed at 225 nm. The method was validated for specificity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness. The calibration plot was linear over the concentration range of 1-100 μg/mL having a correlation coefficient (r2) of 0.999. Limits of detection and quantification were 0.3 and 1μg/mL, respectively. Intra-day and inter-day precision (% RSD) was 0.65 and 0.79 respectively. The proposed method was used to investigate the degradation kinetics of MET under different stress conditions employed. Degradation of MET followed a pseudo-first-order kinetics, and rate constant (K), time left for 50% potency (t1/2), and time left for 90% potency 090) were calculated.

  1. Preferential Formation of Benzo[a]pyrene Adducts at Lung Cancer Mutational Hotspots in P53

    Science.gov (United States)

    Denissenko, Mikhail F.; Pao, Annie; Tang, Moon-Shong; Pfeifer, Gerd P.

    1996-10-01

    Cigarette smoke carcinogens such as benzo[a]pyrene are implicated in the development of lung cancer. The distribution of benzo[a]pyrene diol epoxide (BPDE) adducts along exons of the P53 gene in BPDE-treated HeLa cells and bronchial epithelial cells was mapped at nucleotide resolution. Strong and selective adduct formation occurred at guanine positions in codons 157, 248, and 273. These same positions are the major mutational hotspots in human lung cancers. Thus, targeted adduct formation rather than phenotypic selection appears to shape the P53 mutational spectrum in lung cancer. These results provide a direct etiological link between a defined chemical carcinogen and human cancer.

  2. Degradation of caffeine by ozone oxidation in aqueous solution%水溶液中咖啡因的臭氧氧化降解研究

    Institute of Scientific and Technical Information of China (English)

    徐丹瑶; 缪恒锋; 任洪艳; 赵明星; 阮文权

    2013-01-01

    采用臭氧氧化对咖啡因(CAF)进行降解,考察了操作参数对CAF降解过程的影响,利用UPLC-MS对臭氧氧化前后的CAF溶液进行扫描,通过降解产物的相对分子质量并结合前人研究结果推测降解途径.结果表明,臭氧氧化能有效降解CAF,降解过程符合拟一级反应动力学,呈两阶段反应.随温度的升高,kobs1和kobs2分别在30℃和20℃达到最大值.CAF初始质量浓度的升高、pH值的降低、碳酸氢根和叔丁醇的存在均会降低CAF的降解效率.H2O2的投加对CAF的臭氧降解具有低促高抑的效果.CAF降解后产生7种可能的降解中间产物,降解过程可能主要通过CAF嘌呤环上臭氧分子直接加成反应、脱甲基反应、羰基化反应及水分子加成反应来实现,未发现·OH直接攻击CAF的C4=C5双键反应生成的转化产物.%This paper takes it as its objective to make clear the factors affecting the degradation of caffeine by ozone oxidation and then propose its tentative degradation pathway.For this research purpose,we have carried out kinetic studies on the caffeine degradation process under different operating conditions,such as reaction temperatures,initial concentrations of the caffeine,the pH value of the solution,the addition of radicals scavenger (bicarbonate radical and tertiary butanol),as well as the hydrogen peroxide.So far as we know,the degradation of caffeine by ozone oxidation tends to follow the pseudofirst-order kinetic model in two ozone oxidation stages,with the observed rate constant of the second ozone oxidation stage,kobs2,being higher than the observed rate constant in the first corresponding stage,kobsl.Whereas the kobsl of the caffeine degra dation tends to increase exponentially with the temperature rising from 10 ℃ to 30 ℃,kobs2 drops at the temperature above 20℃.While the increase of the initial concentration of caffeine and the decrease of pH value of the solution along with the added radical scavengers may

  3. Oxidation of polycyclic aromatic hydrocarbons using partially purified laccase from residual compost of agaricus bisporus

    Energy Technology Data Exchange (ETDEWEB)

    Mayolo-Deloisa, K. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Center for Biotechnology-FEMSA, Monterrey Institute of Technology, Campus Monterrey, Monterrey (Mexico); Machin-Ramirez, C. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Faculty of Chemical Sciences and Engineering, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico); Rito-Palomares, M. [Center for Biotechnology-FEMSA, Monterrey Institute of Technology, Campus Monterrey, Monterrey (Mexico); Trejo-Hernandez, M.R. [Center for Biotechnology Research, Autonomous University of Morelos State, Cuernavaca, Morelos (Mexico)

    2011-08-15

    Laccase partially purified from residual compost of Agaricus bisporus by an aqueous two-phase system (Lac ATPS) was used in degrading polycyclic aromatic hydrocarbons: fluorene (Flu), phenanthrene (Phe), anthracene (Ant), benzo[a]pyrene (BaP), and benzo[a]anthracene (BaA). The capacity of the enzyme to oxidize polyaromatic compounds was compared to that of the crude laccase extract (CE). After treatment of 72 h, Lac ATPS and CE were not capable of oxidizing Flu and Phe, while Ant, BaP, and BaA were oxidized, resulting in percentages of oxidation of 11.2 {+-} 1, 26 {+-} 2, and 11.7 {+-} 4 % with CE, respectively. When Lac ATPS was used, the following percentages of oxidation were obtained: 11.4 {+-} 3 % for Ant, 34 {+-} 0.1 % for BaP, and 13.6 {+-} 2 % for BaA. The results reported here demonstrate the potential application of Lac ATPS for the oxidation of polycyclic aromatic hydrocarbons. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Electrochemical degradation of the antihypertensive losartan in aqueous medium by electro-oxidation with boron-doped diamond electrode.

    Science.gov (United States)

    Salazar, Claudio; Contreras, Nicole; Mansilla, Héctor D; Yáñez, Jorge; Salazar, Ricardo

    2016-12-01

    In this work the electrochemical oxidation of losartan, an emerging pharmaceutical pollutant, was studied. Electrochemical oxidation was carried out in batch mode, in an open and undivided cell of 100cm(3) using a boron-doped diamond (BDD)/stainless steel system. With Cl(-) medium 56% of mineralization was registered, while with the trials containing SO4(2-) as supporting electrolyte a higher mineralization yield of 67% was reached, even obtaining a total removal of losartan potassium at 80mAcm(-2) and 180min of reaction time at pH 7.0. Higher losartan potassium concentrations enhanced the mineralization degree and the efficiency of the electrochemical oxidation process. During the mineralization up to 4 aromatic intermediates were identified by ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Moreover, short-linear carboxylic acids, like oxalic, succinic and oxamic were detected and quantified by ion-exclusion HPLC. Finally, the ability of the electrochemical oxidation process to mineralize dissolved commercial tablets containing losartan was achieved, obtaining TOC removal up to 71% under optimized conditions (10mAcm(-2), 0.05M Na2SO4, pH 7.0 and 25°C and 360min of electrolysis). PMID:27180209

  5. Selective oxidative degradation of toluene for the recovery of surfactant by an electro/Fe²⁺/persulfate process.

    Science.gov (United States)

    Long, Anhua; Zhang, Hui

    2015-08-01

    An electro/Fe(2+)/persulfate process has been conducted for toluene removal from surfactant (SDS) flushing solution, and the pseudo-second-order reaction rate constant (k2 value) of toluene removal has been optimized by a response surface methodology (RSM). The results indicated that in this process, the reaction between persulfate and externally added Fe(2+) generates sulfate-free radicals, and at the same time, Fe(2+) is electro-regenerated at the cathode by the reduction of Fe(3+). RSM based on Box-Behnken design (BBD) has been applied to analyze the experimental variables, of which the concentrations of persulfate and Fe(2+) showed a positive effect on the rate constant of toluene removal, whereas the concentration of SDS showed a negative effect. The interactions between pairs of variables proved to be significant, such as between SDS, persulfate, and Fe(2+) concentrations. ANOVA results confirmed that the proposed models were accurate and reliable for analysis of the variables of the electro/Fe(2+)/persulfate process. The shapes of the 3D response surfaces and contour plots showed that the SDS, persulfate, and Fe(2+) concentrations substantially affected the k2 value of toluene removal. The results indicated that increasing persulfate or Fe(2+) concentration increased the k2 value, whereas increasing SDS concentration decreased the k2 value. The reaction intermediates have been identified by GC-MS, and a plausible degradation pathway for toluene degradation is proposed.

  6. Alterations to proteome and tissue recovery responses in fish liver caused by a short-term combination treatment with cadmium and benzo[a]pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Costa, P.M., E-mail: pmcosta@fct.unl.p [IMAR-Instituto do Mar, Departamento de Ciencias e Engenharia do Ambiente, Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Chicano-Galvez, E.; Lopez Barea, J. [Departamento de Bioquimica y Biologia Molecular, Universidad de Cordoba, Campus de Rabanales, Edificio Severo Ochoa, 14071 Cordoba (Spain); DelValls, T.A. [UNESCO/UNITWIN/WiCop Chair-Departamento de Quimica Fisica, Facultad de Ciencias del Mar y Ambientales, Universidad de Cadiz, Poligono rio San Pedro s/n, 11510 Puerto Real, Cadiz (Spain); Costa, M.H. [IMAR-Instituto do Mar, Departamento de Ciencias e Engenharia do Ambiente, Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal)

    2010-10-15

    The livers of soles (Solea senegalensis) injected with subacute doses of cadmium (Cd), benzo[a]pyrene (B[a]P), or their combination, were screened for alterations to cytosolic protein expression patterns, complemented by cytological and histological analyses. Cadmium and B[a]P, but not combined, induced hepatocyte apoptosis and Kupfer cell hyperplasia. Proteomics, however, suggested that apoptosis was triggered through distinct pathways. Cadmium and B[a]P caused upregulation of different anti-oxidative enzymes (peroxiredoxin and glutathione peroxidase, respectively) although co-exposure impaired induction. Similarly, apoptosis was inhibited by co-exposure, to which may have contributed a synergistic upregulation of tissue metalloproteinase inhibitor, {beta}-actin and a lipid transport protein. The regulation factors of nine out of eleven identified proteins of different types revealed antagonistic or synergistic effects between Cd and B[a]P at the prospected doses after 24 h of exposure. The results indicate that co-exposure to Cd and B[a]P may enhance toxicity by impairing specific responses and not through cumulative damage. - The interaction between cadmium and benzo[a]pyrene impairs specific responses to toxicity and tissue repair mechanisms.

  7. Degradation of 4,6-dinitro-o-cresol from water by anodic oxidation with a boron-doped diamond electrode

    Energy Technology Data Exchange (ETDEWEB)

    Flox, Cristina [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Garrido, Jose Antonio [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Rodriguez, Rosa Maria [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Centellas, Francesc [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Cabot, Pere-Lluis [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Arias, Conchita [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: brillas@ub.edu

    2005-06-10

    Anodic oxidation of 4,6-dinitro-o-cresol (DNOC) has been studied in a cell of 100 ml with a boron-doped diamond anode and a graphite cathode, both of 3-cm{sup 2} area. Solutions containing up to approximately 240 mg l{sup -1} of compound in the pH range 2.0-12.0 have been treated at 100, 300 and 450 mA between 15 and 50 deg C. Total mineralization is always achieved due to the great amount of hydroxyl radical ({center_dot}OH) produced as oxidant on the anode surface. Total organic carbon is more rapidly removed in acid medium, being the optimum pH 3.0. The degradation rate increases when temperature, current and DNOC concentration increase. However, at 100 mA depollution becomes more effective from 71 mg l{sup -1} of initial pollutant. A pseudo first-order kinetics for DNOC decay is always found by reversed-phase chromatography, with a rate constant practically independent of pH, as expected if the same electroactive species is oxidized in all media. Ion-exclusion chromatography allowed the detection of oxalic acid as the ultimate carboxylic acid. The mineralization process leads to the complete release of NO{sub 3} {sup -} ions from the destruction of nitroderivative intermediates. These products are oxidized simultaneously with accumulated oxalic acid up to the end of electrolyses. Comparative treatment of the same solutions with a Pt anode yields a quite poor depollution because of the generation of much lower amounts of reactive {center_dot}OH on its surface.

  8. Degradation of 4,6-dinitro-o-cresol from water by anodic oxidation with a boron-doped diamond electrode

    International Nuclear Information System (INIS)

    Anodic oxidation of 4,6-dinitro-o-cresol (DNOC) has been studied in a cell of 100 ml with a boron-doped diamond anode and a graphite cathode, both of 3-cm2 area. Solutions containing up to approximately 240 mg l-1 of compound in the pH range 2.0-12.0 have been treated at 100, 300 and 450 mA between 15 and 50 deg C. Total mineralization is always achieved due to the great amount of hydroxyl radical (·OH) produced as oxidant on the anode surface. Total organic carbon is more rapidly removed in acid medium, being the optimum pH 3.0. The degradation rate increases when temperature, current and DNOC concentration increase. However, at 100 mA depollution becomes more effective from 71 mg l-1 of initial pollutant. A pseudo first-order kinetics for DNOC decay is always found by reversed-phase chromatography, with a rate constant practically independent of pH, as expected if the same electroactive species is oxidized in all media. Ion-exclusion chromatography allowed the detection of oxalic acid as the ultimate carboxylic acid. The mineralization process leads to the complete release of NO3- ions from the destruction of nitroderivative intermediates. These products are oxidized simultaneously with accumulated oxalic acid up to the end of electrolyses. Comparative treatment of the same solutions with a Pt anode yields a quite poor depollution because of the generation of much lower amounts of reactive ·OH on its surface

  9. Analytical aspects of the remediation of soil by wet oxidation - Characterisation of tar contaminants and their degradation products

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Nielsen, T.; Plöger, A.;

    1999-01-01

    Wet oxidation of tar compounds gives rise to a wide range of products. Due to the incorporation of oxygen, these products become increasingly more water soluble and the analytical strategy has to take into account the different physical/chemicalproperties of the compounds. An interplay between ga...... chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography (HPLC) and ion chromatography (IC) has been applied to meet these requirements....

  10. Degradation of solid oxide cells during co-electrolysis of steam and carbon dioxide at high current densities

    DEFF Research Database (Denmark)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Mogensen, Mogens Bjerg

    2016-01-01

    In this work, the durability of Ni–YSZ based solid oxide cells was investigated during co-electrolysis of steam and carbon dioxide (45% H2O + 45% CO2 + 10% H2) at current density of −1.5 or −2.0 A cm−2. The cell consists of ∼300 μm Ni–YSZ support, ∼10 μm Ni–YSZ electrode, ∼10 μm YSZ electrolyte...

  11. Phosphatase activity in commercial spleen exonuclease decreases the recovery of benzo[a]pyrene and N-hydroxy-2-naphthylamine DNA adducts by 32P-postlabeling.

    Science.gov (United States)

    Adams, S P; Laws, G M; Selden, J R; Nichols, W W

    1994-05-15

    Spleen exonuclease, which degrades nucleic acids into single 3'-nucleotides, is used in the detection of DNA adducts by 32P-postlabeling. Contamination of the exonuclease with phosphatase activity can reduce the recovery of benzo[a]pyrene and N-hydroxy-2-naphthylamine DNA adducts by 32P-postlabeling. Four preparations of spleen exonuclease containing varying levels of phosphatase activity (2-naphthylamine DNA adducts. Surprisingly, recovery of these DNA adducts was nearly 10 times greater using nuclease P1 than when using 1-butanol extraction for adduct enrichment, since arylamine DNA adducts have previously been reported to be poorly detected by 32P-postlabeling after nuclease P1 treatment. Our data indicate that the hydrolysis of DNA by spleen exonuclease may be an important source of variability in both qualitative and quantitative analysis of adducts by 32P-postlabeling. PMID:8059938

  12. Transcriptomic changes in zebrafish embryos and larvae following benzo[a]pyrene exposure

    Science.gov (United States)

    Benzo[a]pyrene (BaP) is an environmentally relevant carcinogenic and endocrine disrupting compound that causes immediate, long-term, and multigenerational health deficits in mammals and fish. Previously, we found that BaP alters DNA methylation patterns in developing zebrafish, which may affect gene...

  13. Benzo[a]pyrene decreases global and gene specific DNA methylation during zebrafish development

    Science.gov (United States)

    DNA methylation is important for gene regulation and is vulnerable to early-life exposure to environmental contaminants. We found that direct waterborne benzo[a]pyrene (BaP) exposure at 24 'g/L from 2.5 to 96 hours post fertilization (hpf) to zebrafish embryos significantly decreased global cytosine...

  14. Hypoxia diminishes the detoxification of the environmental mutagen benzo[a]pyrene

    NARCIS (Netherlands)

    Schults, Marten A.; Sanen, Kathleen; Godschalk, Roger W.; Theys, Jan; van Schooten, Frederik J.; Chiu, Roland K.

    2014-01-01

    Hypoxia promotes genetic instability and is therefore an important factor in carcinogenesis. We have previously shown that activation of the hypoxia responsive transcription factor HIF alpha can enhance the mutagenic phenotype induced by the environmental mutagen benzo[a]pyrene (BaP). To further elu

  15. Benzo(A)pyrene Decreases Brain and Ovarian Aromatase mRNA Expression

    Science.gov (United States)

    The higher molecular weight polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BaP) are typically associated with genotoxicity, however newer evidence suggests that these compounds may also act as endocrine system disruptors. We hypothesized that a target for reproductive or development...

  16. Metabolic activation and DNA binding of benzo(a)pyrene in cultured human bronchus

    DEFF Research Database (Denmark)

    1977-01-01

    Human bronchus is one target site for the carcinogenic action of tobacco smoke, which contains chemical carcinogens, including benzo(a)pyrene. Human bronchi were obtained from surgery or “immediate” autopsy and then cultured in a chemically defined medium. The cultured bronchi were exposed...

  17. Benzo(a)pyrene induced structural and functional modifications in lung cystatin.

    Science.gov (United States)

    Khan, Mohd Shahnawaz; Priyadarshini, Medha; Shah, Aaliya; Tabrez, Shams; Jagirdar, Haseeb; Alsenaidy, Abdulrahman M; Bano, Bilqees

    2013-10-01

    Cystatins are thiol proteinase inhibitors ubiquitously present in the mammalian body. They serve a protective function to regulate the activities of endogenous proteinases, which may cause uncontrolled proteolysis and damage. In the present study, the effect of benzo(a)pyrene [BaP] on lung cystatin was studied to explore the hazardous effects of environmental pollutant on structural and functional integrity of the protein. The basic binding interaction was studied by UV-absorption, FT-IR, and fluorescence spectroscopy. The enhancement of total protein fluorescence with a red shift of 5 nm suggests structural scratch of lung cystatin by benzo(a)pyrene. Further, ANS binding studies reaffirm the unfolding of the thiol protease inhibitor (GLC-I) after treating with benzo(a)pyrene. The results of FT-IR spectroscopy reflect perturbation of the secondary conformation (alpha-helix to β-sheet) in goat lung cystatin on interaction with BaP. Finally, functional inactivation of cystatin on association with BaP was checked by its papain inhibitory activity. Benzo(a)pyrene (10 μM) caused complete inactivation of goat lung cystatin. Benzo(a)pyrene-induced loss of structure and function in the thiol protease inhibitor could provide a caution for lung injury caused by the pollutants and smokers.

  18. Visible light-driven photocatalytic degradation of the organic pollutant methylene blue with hybrid palladium–fluorine-doped titanium oxide nanoparticles

    International Nuclear Information System (INIS)

    The synthesis of mesoporous aggregates of titanium oxide nanoparticles (F0) is described using a very cheap and simple synthetic protocol. This consists of the reaction of titanium tetraisopropoxide and a solution of HNO3 in water (pH 2.0) and subsequent filtration. In addition, fluorine-doped titanium oxides (F1, F2, F5 and F10) were synthesized using the same method, adding increasing amounts of NaF to the reaction mixture (avoiding the use of expensive reagents such as NH4F or trifluoroacetic acid). The resulting materials were calcined at different temperatures (500, 600 and 650 °C) giving particles sized between 10 and 20 nm. Furthermore, a hybrid F-doped TiO2 with supported palladium nanoparticles of ca. 20 nm (F5-500-Pd1) was synthesized by grafting an organometallic palladium(II) salt namely [Pd(cod)Cl2] (cod = 1,5-cyclooctadiene). Photocatalytic studies of the degradation of methylene blue (MB) were carried out under UV light using all the synthesized material (non-doped an F-doped TiO2), observing that the increase in the quantity of fluorine has a positive effect on the photocatalytic activity. F5-500 is apparently the material which has the most convenient structural properties (in terms of surface area and anatase/rutile ratio) and thus a higher photocatalytic activity. The hybrid material F-doped TiO2–Pd nanoparticles (F5-500-Pd1) has a lower band gap value than F5-500, and thus photocatalytic degradation of MB under LED visible light was achieved using F5-500-Pd1 as photocatalyst

  19. Visible light-driven photocatalytic degradation of the organic pollutant methylene blue with hybrid palladium–fluorine-doped titanium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lázaro-Navas, Sonia; Prashar, Sanjiv; Fajardo, Mariano; Gómez-Ruiz, Santiago, E-mail: santiago.gomez@urjc.es [Universidad Rey Juan Carlos, Departamento de Biología y Geología, Física y Química Inorgánica, ESCET (Spain)

    2015-02-15

    The synthesis of mesoporous aggregates of titanium oxide nanoparticles (F0) is described using a very cheap and simple synthetic protocol. This consists of the reaction of titanium tetraisopropoxide and a solution of HNO{sub 3} in water (pH 2.0) and subsequent filtration. In addition, fluorine-doped titanium oxides (F1, F2, F5 and F10) were synthesized using the same method, adding increasing amounts of NaF to the reaction mixture (avoiding the use of expensive reagents such as NH{sub 4}F or trifluoroacetic acid). The resulting materials were calcined at different temperatures (500, 600 and 650 °C) giving particles sized between 10 and 20 nm. Furthermore, a hybrid F-doped TiO{sub 2} with supported palladium nanoparticles of ca. 20 nm (F5-500-Pd1) was synthesized by grafting an organometallic palladium(II) salt namely [Pd(cod)Cl{sub 2}] (cod = 1,5-cyclooctadiene). Photocatalytic studies of the degradation of methylene blue (MB) were carried out under UV light using all the synthesized material (non-doped an F-doped TiO{sub 2}), observing that the increase in the quantity of fluorine has a positive effect on the photocatalytic activity. F5-500 is apparently the material which has the most convenient structural properties (in terms of surface area and anatase/rutile ratio) and thus a higher photocatalytic activity. The hybrid material F-doped TiO{sub 2}–Pd nanoparticles (F5-500-Pd1) has a lower band gap value than F5-500, and thus photocatalytic degradation of MB under LED visible light was achieved using F5-500-Pd1 as photocatalyst.

  20. Enhanced photocatalytic degradation activity over TiO2 nanotubes co-sensitized by reduced graphene oxide and copper(II) meso-tetra(4-carboxyphenyl)porphyrin

    Science.gov (United States)

    Wei, Meng; Wan, Junmin; Hu, Zhiwen; Peng, Zhiqin; Wang, Bing

    2016-07-01

    In this paper, TiO2 nanotubes (TNT) co-sensitized with copper(II) meso-tetra(4-carboxyphenyl)porphyrin (CuTCPP) and reduced graphene oxide nanosheets (rGO), which was fabricated through two-step improved hydrothermal method and heating reflux process. The effect of rGO and CuTCPP on the co-photocatalytic behavior of TNT for the degradation of Methylene Blue (MB) were measured under visible light irradiation. The photocatalysts have been characterized and analyzed by high-resolution transmission electron microscopy (TEM), selected area electronic diffraction (SAED), elemental mapping by energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and electron paramagnetic resonance (EPR). The results provide a deeper insight into the co-photocatalytic mechanism of CuTCPP/rGO-TNT nanocomposites. The degradation results showed a purification of more than 95% MB in wastewater, which is about 5 times higher than that of the pure TNT. The results also confirm the prepared CuTCPP/rGO-TNT nanocomposites possess superior co-photocatalytic activities.

  1. A long-term degradation study of power generation characteristics of anode-supported solid oxide fuel cells using LaNi(Fe)O{sub 3} electrode

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Takeshi; Watanabe, Kimitaka; Arakawa, Masayasu; Arai, Hajime [NTT Corporation, NTT Energy and Environment Systems Laboratories, Morinosato-Wakamiya 3-1, Atsugi-shi, Kanagawa 243-0198 (Japan)

    2009-09-05

    The long-term operation of an anode-supported solid oxide fuel cell was examined to study the degradation factor. The cell was constructed using LaNi{sub 0.6}Fe{sub 0.4}O{sub 3} (LNF), alumina-doped scandia stabilized zirconia (SASZ), and NiO-SASZ as the cathode, electrolyte, and anode respectively. The cell had Pt current collectors and was operated for 6500 h. The test was carried out at 1073 K with a constant load of 0.4 A cm{sup -2} and included thermal cycling. The cell voltage degradation rate was below 0.86%/1000 h when the cell was operated for up to 5200 h. Changes in the resistance of the cells during the experiments were analyzed by impedance spectroscopy. The cathode polarization resistance and ohmic resistance increased with time. The elements (Si and B) contained in the water condensed from the cathode exhaust gas were identified using inductively coupled plasma (ICP). (author)

  2. Photo-catalytic Degradation and Sorption of Radio-cobalt from EDTA-Co Complexes Using Manganese Oxide Materials - 12220

    Energy Technology Data Exchange (ETDEWEB)

    Koivula, Risto; Harjula, Risto [University of Helsinki, P.O.Box 55, FI-00014 Helsinki (Finland); Tusa, Esko [Fortum Power and Heat Oy P.O.Box 100, 00048 FORTUM (Finland)

    2012-07-01

    The synthesised cryptomelane-type α-MnO{sub 2} was tested for its Co-57 uptake properties in UV-photo-reactor filled with 10 μM Co-EDTA solution with a background of 10 mM NaNO{sub 3}. High cobalt uptake of 96% was observed after 1 hour of UV irradiation. As for comparison, a well-known TiO{sub 2} (Degussa P25) was tested as reference material that showed about 92% cobalt uptake after six hours of irradiation in identical experiment conditions. It was also noted that the cobalt uptake on cryptomelane with out UV irradiation was modest, only about 10%. Decreasing the pH of the Co-EDTA solution had severe effects on the cobalt uptake mainly due to the rather high point of zero charge of the MnO{sub 2} surface (pzc at pH ∼4.5). Modifying the synthesis procedure we were able to produce a material that functioned well even in solution of pH 3 giving cobalt uptake of almost 99%. The known properties, catalytic and ion exchange, of manganese oxides were simultaneously used for the separation of EDTA complexed Co-57. Tunnel structured cryptomelane -type showed very fast and efficient Co uptake properties outperforming the well known and widely used Degussa P25 TiO{sub 2} in both counts. The layered structured manganese oxide, birnessite, reached also as high Co removal level as the reference material Degussa did but the reaction rate was considerably faster. Since the decontamination solutions are typically slightly acidic and the point of zero charge of the manganese oxides are rather high > pH 4.5 the material had to be modified. This modified material had tolerance to acidic solutions and it's Co uptake performance remained high in the solutions of lower pH (pH 3). Increasing the ion concentration of test solutions, background concentration, didn't affect the final Co uptake level; however, some changes in the uptake kinetics could be seen. The increase in EDTA/MoMO ratio was clearly reflected in the Co uptake curves. The obtained results of manganese

  3. The Effect of Mesoporous Carbon Nitride Modification by Titanium Oxide Nanoparticles on Photocatalytic Degradation of 1,3-Dinitrobenzene

    Directory of Open Access Journals (Sweden)

    Seyyed Ershad Moradi

    2015-11-01

    Full Text Available In the present work, well ordered, mesoporous carbon nitride (MCN sorbent with uniform mesoporous wall, high surface area and pore volume has been fabricated using the simple polymerization reaction between ethylene diamine and carbon tetrachloride in mesoporous silica media, and then modified by TiO2 nanoparticles (Ti-MCN. The structural order and textural properties of the nanoporous materials were studied by XRD, elemental analysis, and nitrogen adsorption–desorption experiments. Photodegradation experiments for 1,3-dinitrobenzene were conducted in batch mode, the Ti-MCN catalysts were found to be more active compared to the free TiO2 nanoparticles for 1,3-dinitrobenzene degradation.

  4. Efficient photocatalytic degradation of acid orange 7 on metal oxide p-n junction composites under visible light

    Science.gov (United States)

    Suk Jang, Jum; Gyu Kim, Hyun; Lee, Se-Hee

    2012-11-01

    MO(=CuO, Co3O4, NiO)/BiVO4 p-n junction composites were synthesized by urea-precipitation and wet impregnation method. The physicochemical and optical properties of the as-prepared materials were investigated by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra. The photocatalytic performance of the as-prepared materials was investigated for decomposition of azo dye, acid orange 7. The CuO/BiVO4 and Co3O4/BiVO4 p-n junction composite photocatalysts exhibited the higher photocatalytic degradation of acid orange 7 than those of BiVO4 and NiO/BiVO4 as-prepared samples under visible light irradiation. We also discussed the mechanism of enhanced photocatalytic activity of p-n junctioned composites based on their energy band structures.

  5. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    Science.gov (United States)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  6. Salicylic acid degradation by advanced oxidation processes. Coupling of solar photoelectro-Fenton and solar heterogeneous photocatalysis.

    Science.gov (United States)

    Garza-Campos, Benjamin; Brillas, Enric; Hernández-Ramírez, Aracely; El-Ghenymy, Abdellatif; Guzmán-Mar, Jorge Luis; Ruiz-Ruiz, Edgar J

    2016-12-01

    A 3.0 L solar flow plant with a Pt/air-diffusion (anode/cathode) cell, a solar photoreactor and a photocatalytic photoreactor filled with TiO2-coated glass spheres has been utilized to couple solar photoelectro-Fenton (SPEF) and solar heterogeneous photocatalysis (SPC) for treating a 165mgL(-1) salicylic acid solution of pH 3.0. Organics were destroyed by OH radicals formed on the TiO2 photocatalyst and at the Pt anode during water oxidation and in the bulk from Fenton's reaction between added Fe(2+) and cathodically generated H2O2, along with the photolytic action of sunlight. Poor salicylic acid removal and mineralization were attained using SPC, anodic oxidation with electrogenerated H2O2 (AO-H2O2) and coupled AO-H2O2-SPC. The electro-Fenton process accelerated the substrate decay, but with low mineralization by the formation of byproducts that are hardly destroyed by OH. The mineralization was strongly increased by SPEF due to the photolysis of products by sunlight, being enhanced by coupled SPEF-SPC due to the additional oxidation by OH at the TiO2 surface. The effect of current density on the performance of both processes was examined. The most potent SPEF-SPC process at 150mAcm(-2) yielded 87% mineralization and 13% current efficiency after consuming 6.0AhL(-1). Maleic, fumaric and oxalic acids detected as final carboxylic acids were completely removed by SPEF and SPEF-SPC.

  7. Rapid liquid chromatography-tandem mass spectrometry analysis of 4-hydroxynonenal for the assessment of oxidative degradation and safety of vegetable oils.

    Science.gov (United States)

    Gabbanini, Simone; Matera, Riccardo; Valvassori, Alice; Valgimigli, Luca

    2015-04-15

    A novel method for the UHPLC-MS/MS analysis of (E)-4-hydroxynonenal (4-HNE) is described. The method is based on derivatization of 4-HNE with pentafluorophenylhydrazine (1) or 4-trifluoromethylphenylhydrazine (2) in acetonitrile in the presence of trifluoroacetic acid as catalyst at room temperature and allows complete analysis of one sample of vegetable oil in only 21 min, including sample preparation and chromatography. The method involving hydrazine 1, implemented in an ion trap instrument with analysis of the transition m/z 337→154 showed LOD=10.9 nM, average accuracy of 101% and precision ranging 2.5-4.0% RSD intra-day (2.7-4.1% RSD inter-day), with 4-HNE standard solutions. Average recovery from lipid matrices was 96.3% from vaseline oil, 91.3% from sweet almond oil and 105.3% from olive oil. The method was tested on the assessment of safety and oxidative degradation of seven samples of dietary oil (soybean, mixed seeds, corn, peanut, sunflower, olive) and six cosmetic-grade oils (avocado, blackcurrant, apricot kernel, echium, sesame, wheat germ) and effectively detected increased 4-HNE levels in response to chemical (Fenton reaction), photochemical, or thermal stress and aging, aimed at mimicking typical oxidation associated with storage or industrial processing. The method is a convenient, cost-effective and reliable tool to assess quality and safety of vegetable oils.

  8. Reduced graphene oxide wrapped ZnS–Ag{sub 2}S ternary composites synthesized via hydrothermal method: Applications in photocatalyst degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Amaranatha Reddy, D.; Ma, Rory [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Choi, Myong Yong, E-mail: mychoi@gnu.ac.kr [Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju 660-701 (Korea, Republic of); Kim, Tae Kyu, E-mail: tkkim@pusan.ac.kr [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609-735 (Korea, Republic of)

    2015-01-01

    Highlights: • Hydrothermal synthesis of ternary ZnS–Ag{sub 2}S–RGO nanostructures without any additives. • Significant improvement of the photocatalytic activity in RGO wrapped composites. • Near white light emission and stable cycling can lead these composites to find application in near UV-white LEDs and environmental protection issues. - Abstract: In this work, we have successfully synthesized ternary nanohybrid composite, ZnS–Ag{sub 2}S wrapped with reduced graphene oxide (RGO) using hydrothermal method without any surfactant. We have accessed the photocatalytic ability of ZnS–Ag{sub 2}S–RGO nanocomposite using the oxidation of Rhodamine B (RhB) under simulated sunlight irradiation. The superior photocatalytic ability of ZnS–Ag{sub 2}S–RGO compared to bare ZnS, was ascribed to an efficient charge transfer from ZnS to Ag{sub 2}S and graphene sheets. The recyclability results also demonstrated the excellent stability and reliability of the ZnS–Ag{sub 2}S–RGO. In addition to the excellent photocatalytic degradation properties, the synthesized ZnS–Ag{sub 2}S–RGO nanocomposite exhibited near white light emission, which implies that careful design and control of the composition could be lead to find application in near UV-white LEDs. The present work provides new insights into the synthesis and characterizations of ternary ZnS–Ag{sub 2}S–RGO nanocomposites and its wide applications in the environmental protection issues.

  9. Biomolecule-assisted synthesis of In(OH)₃ nanocubes and In₂O₃ nanoparticles: photocatalytic degradation of organic contaminants and CO oxidation.

    Science.gov (United States)

    Nayak, Arpan Kumar; Lee, Seungwon; Sohn, Youngku; Pradhan, Debabrata

    2015-12-01

    The synthesis of nanostructured materials without any hazardous organic chemicals and expensive capping reagents is one of the challenges in nanotechnology. Here we report on the L-arginine (a biomolecule)-assisted synthesis of single crystalline cubic In(OH)3 nanocubes of a size in the range of 30-60 nm along the diagonal using hydrothermal methods. Upon calcining at 750 °C for 1 h in air, In(OH)3 nanocubes are transformed into In2O3 nanoparticles (NPs) with voids. The morphology transformation and formation of voids with the increase of the calcination temperature is studied in detail. The possible mechanism of the voids' formation is discussed on the basis of the Kirkendall effect. The photocatalytic properties of In(OH)3 nanocubes and In2O3 NPs are studied for the degradation of rhodamin B and alizarin red S. Furthermore, the CO oxidation activity of In(OH)3 nanocubes and In2O3 NPs is examined. The photocatalytic and CO oxidation activity are measured to be higher for In2O3 NPs than for In(OH)3 nanocubes. This is attributed to the lower energy gap and higher specific surface area of the former. The present green synthesis has potential for the synthesis of other inorganic nanomaterials.

  10. Biomolecule-assisted synthesis of In(OH)3 nanocubes and In2O3 nanoparticles: photocatalytic degradation of organic contaminants and CO oxidation

    Science.gov (United States)

    Nayak, Arpan Kumar; Lee, Seungwon; Sohn, Youngku; Pradhan, Debabrata

    2015-12-01

    The synthesis of nanostructured materials without any hazardous organic chemicals and expensive capping reagents is one of the challenges in nanotechnology. Here we report on the L-arginine (a biomolecule)-assisted synthesis of single crystalline cubic In(OH)3 nanocubes of a size in the range of 30-60 nm along the diagonal using hydrothermal methods. Upon calcining at 750 °C for 1 h in air, In(OH)3 nanocubes are transformed into In2O3 nanoparticles (NPs) with voids. The morphology transformation and formation of voids with the increase of the calcination temperature is studied in detail. The possible mechanism of the voids’ formation is discussed on the basis of the Kirkendall effect. The photocatalytic properties of In(OH)3 nanocubes and In2O3 NPs are studied for the degradation of rhodamin B and alizarin red S. Furthermore, the CO oxidation activity of In(OH)3 nanocubes and In2O3 NPs is examined. The photocatalytic and CO oxidation activity are measured to be higher for In2O3 NPs than for In(OH)3 nanocubes. This is attributed to the lower energy gap and higher specific surface area of the former. The present green synthesis has potential for the synthesis of other inorganic nanomaterials.

  11. Electrochemical degradation of nitrobenzene by anodic oxidation on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode.

    Science.gov (United States)

    Chen, Yong; Li, Hongyi; Liu, Weijing; Tu, Yong; Zhang, Yaohui; Han, Weiqing; Wang, Lianjun

    2014-10-01

    The interlayer of Sb-doped SnO2 (SnO2-Sb) and TiO2 nanotubes (TiO2-NTs) on Ti has been introduced into the PbO2 electrode system with the aim to reveal the mechanism of enhanced electrochemical performance of TiO2-NTs/SnO2-Sb/PbO2 electrode. In contrast with the traditional Ti/SnO2-Sb/PbO2 electrode, the constructed PbO2 electrode has a more regular and compact morphology with better oriented crystals of lower size. The TiO2-NTs/SnO2-Sb interlayer prepared by electrodeposition process improves PbO2 coating structure effectively, and enhances the electrochemical performance of PbO2 electrode. Kinetic analyses indicated that the electrochemical oxidation of nitrobenzene on the PbO2 electrodes followed pseudo-first-order reaction, and mass transport was enhanced at the constructed electrode. The accumulation of nitrocompounds of degradation intermediates on constructed electrode was lower, and almost all of the nitro groups were eliminated from aromatic rings after 6h of electrolysis. Higher combustion efficiency was obtained on the constructed TiO2-NTs/SnO2-Sb/PbO2 electrode. The intermediates of nitrobenzene oxidation were confirmed by IC and GC/MS.

  12. Oxidative degradation of phenol by manganese dioxide%δ-MnO2氧化降解苯酚的机理研究

    Institute of Scientific and Technical Information of China (English)

    徐建; 张莹; 李蕾; 郭昌胜; 张远

    2013-01-01

    δ-MnO2以水羟锰矿和水钠锰矿的形式普遍存在于陆地和海洋环境中,是酚类等有机污染物发生非生物转化的重要氧化剂.本文研究了实验室制备的δ-MnO2悬浮液对苯酚的去除作用,同时讨论了pH、二氧化锰投加量、离子强度、共存金属离子和腐殖酸等不同影响因素对苯酚去除效率的影响.结果表明,苯酚氧化降解的最佳pH和δ-MnO2投加量分别为3.62和0.13 mg·L-1.溶液中共存的Na+和Mn2+会对苯酚氧化降解产生抑制作用,而Mg2+和Ca2+对反应过程没有明显的影响.溶液中共存的腐殖酸也对苯酚的降解过程产生了抑制作用,随着腐殖酸的浓度由1 mg·L-1增加到5 mg·L-1,苯酚的去除率从96.9%降为78.9%.GC-MS分析发现,对苯二酚为该过程的主要中间产物,同时给出了苯酚在δ-MnO2存在时的可能降解机制.%Manganese dioxides ( δ-MnO2 ) mainly exist in the form of vernadite and birnessite in the natural environment, which are considered to be important oxidants during the abiotic transformation of phenolic compounds. In this study, δ-MnO2 was synthesized by a facile method, and its ability for the degradation of aqueous phenol was investigated. Impacts of solution pH, δ-MnO2 loading, ionic strength, coexistence metal ions, and humic acid on the degradation of aqueous phenol were studied. The optimum solution pH and δ-MnO2 loading were determined to be 3. 62 and 0. 13 mg·L-1 , respectively. The coexistence of Na+ and Mn2+ showed inhibition effect on the oxidative degradation process, while Mg2 + and Ca + did not show any obvious effect during the experimental process. The removal efficiency of phenol decreased from 96. 9% to 78. 9% when the concentration of humic acid in the reaction solution increased from 1 mg· L -1 to 5 mg·L -1 . GC-MS was applied to identity the reaction intermediates, and hydroquinone was found to be the main reaction intermediate in the degradation system. Based on the above

  13. Hydroxyl-radical-induced degradative oxidation of beta-lactam antibiotics in water: absolute rate constant measurements.

    Science.gov (United States)

    Dail, Michelle K; Mezyk, Stephen P

    2010-08-19

    The beta-lactam antibiotics are some of the most prevalent pharmaceutical contaminants currently being detected in aquatic environments. Because the presence of any trace level of antibiotic in water may adversely affect aquatic ecosystems and contribute to the production of antibiotic-resistant bacteria, active removal by additional water treatments, such as using advanced oxidation and reduction processes (AO/RPs), may be required. However, to ensure that any AOP treatment process occurs efficiently and quantitatively, a full understanding of the kinetics and mechanisms of all of the chemical reactions involved under the conditions of use is necessary. In this study, we report on our kinetic measurements for the hydroxyl-radical-induced oxidation of 11 beta-lactam antibiotics obtained using electron pulse radiolysis techniques. For the 5-member ring species, an average reaction rate constant of (7.9 +/- 0.8) x 10(9) M(-1) s(-1) was obtained, slightly faster than for the analogous 6-member ring containing antibiotics, (6.6 +/- 1.2) x 10(9) M(-1) s(-1). The consistency of these rate constants for each group infers a common reaction mechanism, consisting of the partitioning of the hydroxyl radical between addition to peripheral aromatic rings and reaction with the central double-ring core of these antibiotics.

  14. Degradation of antibiotic activity during UV/H2O2 advanced oxidation and photolysis in wastewater effluent.

    Science.gov (United States)

    Keen, Olya S; Linden, Karl G

    2013-11-19

    Trace levels of antibiotics in treated wastewater effluents may present a human health risk due to the rise of antibacterial activity in the downstream environments. Advanced oxidation has a potential to become an effective treatment technology for transforming trace antibiotics in wastewater effluents, but residual or newly generated antibacterial properties of transformation products are a concern. This study demonstrates the effect of UV photolysis and UV/H2O2 advanced oxidation on transformation of 6 antibiotics, each a representative of a different structural class, in pure water and in two different effluents and reports new or confirmatory photolysis quantum yields and hydroxyl radical rate constants. The decay of the parent compound was monitored with HPLC/ITMS, and the corresponding changes in antibacterial activity were measured using bacterial inhibition assays. No antibacterially active products were observed following treatment for four of the six antibiotics (clindamycin, ciprofloxacin, penicillin-G, and trimethoprim). The remaining two antibiotics (erythromycin and doxycycline) showed some intermediates with antibacterial activity at low treatment doses. The antibacterially active products lost activity as the UV dose increased past 500 mJ/cm(2). Active products were observed only in wastewater effluents and not in pure water, suggesting that complex secondary reactions controlled by the composition of the matrix were responsible for their formation. This outcome emphasizes the importance of bench-scale experiments in realistic water matrices. Most importantly, the results indicate that photosensitized processes during high dose wastewater disinfection may be creating antibacterially active transformation products from some common antibiotics.

  15. Ultrahigh-performance liquid chromatography-ultraviolet absorbance detection-high-resolution-mass spectrometry combined with automated data processing for studying the kinetics of oxidative thermal degradation of thyroxine in the solid state.

    Science.gov (United States)

    Neu, Volker; Bielow, Chris; Reinert, Knut; Huber, Christian G

    2014-12-01

    Levothyroxine as active pharmaceutical ingredient of formulations used for the treatment of hypothyroidism is distributed worldwide and taken by millions of people. An important issue in terms of compound stability is its capability to react with ambient oxygen, especially in case of long term compound storage at elevated temperature. In this study we demonstrate that ultrahigh-performance liquid chromatography coupled to UV spectrometry and high-resolution mass spectrometry (UHPLC-UV-HRMS) represent very useful approaches to investigate the influence of ambient oxygen on the degradation kinetics of levothyroxine in the solid state at enhanced degradation conditions. Moreover, the impurity pattern of oxidative degradation of levothyroxine is elucidated and classified with respect to degradation kinetics at different oxygen levels. Kinetic analysis of thyroxine bulk material at 100 °C reveals bi-phasic degradation kinetics with a distinct change in degradation phases dependent on the availability of oxygen. The results clearly show that contact of the bulk material to ambient oxygen is a key factor for fast compound degradation. Furthermore, the combination of time-resolved HRMS data and automated data processing is shown to allow insights into the kinetics and mechanism of impurity formation on individual compound basis. By comparing degradation profiles, four main classes of profiles linked to reaction pathways of thyroxine degradation were identifiable. Finally, we show the capability of automated data processing for the matching of different stressing conditions, in order to extract information about mechanistic similarities. As a result, degradation kinetics is influenced by factors like availability of oxygen, stressing time, or stressing temperature, while the degradation mechanisms appear to be conserved.

  16. Degradation of the beta-blocker propranolol by electrochemical advanced oxidation processes based on Fenton's reaction chemistry using a boron-doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Isarain-Chavez, Eloy; Rodriguez, Rosa Maria; Garrido, Jose Antonio; Arias, Conchita; Centellas, Francesc; Cabot, Pere Lluis [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.ed [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-12-15

    The electro-Fenton (EF) and photoelectro-Fenton (PEF) degradation of solutions of the beta-blocker propranolol hydrochloride with 0.5 mmol dm{sup -3} Fe{sup 2+} at pH 3.0 has been studied using a single cell with a boron-doped diamond (BDD) anode and an air diffusion cathode (ADE) for H{sub 2}O{sub 2} electrogeneration and a combined cell containing the above BDD/ADE pair coupled in parallel to a Pt/carbon felt (CF) cell. This naphthalene derivative can be mineralized by both methods with a BDD anode. Almost overall mineralization is attained for the PEF treatments, more rapidly with the combined system due to the generation of higher amounts of hydroxyl radical from Fenton's reaction by the continuous Fe{sup 2+} regeneration at the CF cathode, accelerating the oxidation of organics to Fe(III)-carboxylate complexes that are more quickly photolyzed by UVA light. The homologous EF processes are less potent giving partial mineralization. The effect of current density, pH and Fe{sup 2+} and drug concentrations on the oxidation power of PEF process in combined cell is examined. Propranolol decay follows a pseudo first-order reaction in most cases. Aromatic intermediates such as 1-naphthol and phthalic acid and generated carboxylic acids such as maleic, formic, oxalic and oxamic are detected and quantified by high-performance liquid chromatography. The chloride ions present in the starting solution are slowly oxidized at the BDD anode. In PEF treatments, all initial N of propranolol is completely transformed into inorganic ions, with predominance of NH{sub 4}{sup +} over NO{sub 3}{sup -} ion.

  17. A common carcinogen benzo[a]pyrene causes neuronal death in mouse via microglial activation.

    Directory of Open Access Journals (Sweden)

    Kallol Dutta

    Full Text Available BACKGROUND: Benzo[a]pyrene (B[a]P belongs to a class of polycyclic aromatic hydrocarbons that serve as micropollutants in the environment. B[a]P has been reported as a probable carcinogen in humans. Exposure to B[a]P can take place by ingestion of contaminated (especially grilled, roasted or smoked food or water, or inhalation of polluted air. There are reports available that also suggests neurotoxicity as a result of B[a]P exposure, but the exact mechanism of action is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using neuroblastoma cell line and primary cortical neuron culture, we demonstrated that B[a]P has no direct neurotoxic effect. We utilized both in vivo and in vitro systems to demonstrate that B[a]P causes microglial activation. Using microglial cell line and primary microglial culture, we showed for the first time that B[a]P administration results in elevation of reactive oxygen species within the microglia thereby causing depression of antioxidant protein levels; enhanced expression of inducible nitric oxide synthase, that results in increased production of NO from the cells. Synthesis and secretion of proinflammatory cytokines were also elevated within the microglia, possibly via the p38MAP kinase pathway. All these factors contributed to bystander death of neurons, in vitro. When administered to animals, B[a]P was found to cause microglial activation and astrogliosis in the brain with subsequent increase in proinflammatory cytokine levels. CONCLUSIONS/SIGNIFICANCE: Contrary to earlier published reports we found that B[a]P has no direct neurotoxic activity. However, it kills neurons in a bystander mechanism by activating the immune cells of the brain viz the microglia. For the first time, we have provided conclusive evidence regarding the mechanism by which the micropollutant B[a]P may actually cause damage to the central nervous system. In today's perspective, where rising pollution levels globally are a matter of grave concern, our

  18. Flow cytometric measurement of the metabolism of benzo[a]pyrene by mouse liver cells in culture

    International Nuclear Information System (INIS)

    The metabolism of benzo[a]pyrene in individual cells was monitored by flow cytometry. The measurements are based on the alterations that occur in the fluorescence emission spectrum of benzo[a]pyrene when it is converted to various metabolites. Using present instrumentation the technique could easily detect 1x106 molecules per cells of benzo[a]pyrene and 1x107 molecules per cell of the diol epoxide. The analysis of C3H IOT 1/2 mouse fibroblasts growing in culture indicated that there was heterogeneity in the conversion of the parent compound into diol epoxide derivatives suggesting that some variation in sensitivity to transformation by benzo[a]pyrene may be due to differences in cellular metabolism. The technique allows sensitive detection of metabolites in viable cells, and provides a new approach to the study of factors that influence both metabolism and transformation. (orig.)

  19. Pilot-scale UV/H2O2 advanced oxidation process for municipal reuse water: Assessing micropollutant degradation and estrogenic impacts on goldfish (Carassius auratus L.).

    Science.gov (United States)

    Shu, Zengquan; Singh, Arvinder; Klamerth, Nikolaus; McPhedran, Kerry; Bolton, James R; Belosevic, Miodrag; Gamal El-Din, Mohamed

    2016-09-15

    Low concentrations (ng/L-μg/L) of emerging micropollutant contaminants in municipal wastewater treatment plant effluents affect the possibility to reuse these waters. Many of those micropollutants elicit endocrine disrupting effects in aquatic organisms resulting in an alteration of the endocrine system. A potential candidate for tertiary municipal wastewater treatment of these micropollutants is ultraviolet (UV)/hydrogen peroxide (H2O2) as an advanced oxidation process (AOP) which was currently applied to treat the secondary effluent of the Gold Bar Wastewater Treatment Plant (GBWWTP) in Edmonton, AB, Canada. A new approach is presented to predict the fluence-based degradation rate constants (kf') of environmentally occurring micropollutants including carbamazepine [(0.87-1.39) × 10(-3) cm(2)/mJ] and 2,4-Dichlorophenoxyacetic acid (2,4-D) [(0.60-0.91) × 10(-3) cm(2)/mJ for 2,4-D] in a medium pressure (MP) UV/H2O2 system based on a previous bench-scale investigation. Rather than using removal rates, this approach can be used to estimate the performance of the MP UV/H2O2 process for degrading trace contaminants of concern found in municipal wastewater. In addition to the ability to track contaminant removal/degradation, evaluation of the MP UV/H2O2 process was also accomplished by identifying critical ecotoxicological endpoints (i.e., estrogenicity) of the treated wastewater. Using quantitative PCR, mRNA levels of estrogen-responsive (ER) genes ERα1, ERα2, ERβ1, ERβ2 and NPR as well as two aromatase encoding genes (CYP19a and CYP19b) in goldfish (Carassius auratus L.) were measured during exposure to the GBWWTP effluent before and after MP UV/H2O2 treatment (a fluence of 1000 mJ/cm(2) and 20 mg/L of H2O2) in spring, summer and fall. Elevated expression of estrogen-responsive genes in goldfish exposed to UV/H2O2 treated effluent (a 7-day exposure) suggested that the UV/H2O2 process may induce acute estrogenic disruption to goldfish principally because

  20. Alterations in the metabolism of benzo(a)pyrene in syrian hamster embryo (SHE) cells pretreated with phenolic antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Strniste, G.F.; Okinaka, R.T.; Chen, D.J.

    1983-01-01

    Inhibition of chemical- or raddiation-induced neoplasia has been observed in animals whose diets were supplemented with antioxidants commonly used as food additives. Inhibition of the carcinogenicity of benzo(a)pyrene (BaP) or of 7,12-dimenthylbenz(a)anthracene (DMBA) - in rats has been achieved by the addition of the phenolic antioxidants butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) to the diet. Our data suggest that in SHE cells antioxidants inhibit the overall metabolism of BaP to its various oxidized moieties including 7,8-diol- and 7,8,9,10-tetrol-BaP. A plausible explanation for our results with SHE cells is that the antioxidants interact directly with AHH, thus inhibiting AHH metabolic capacity. From analysis of nuclear material from SHE cells (+- antioxidants) incubated for 36 hours with BaP at 1 ..mu..g/ml, it is calculated that 4.6, 2.4 and 2.9 pmol BaP are bound to the DNA isolated from 10/sup 7/ nuclei of control, BHA-(20 ..mu..g/ml) and p-MP-(10 ..mu..g/ml) treated cultures, respectively.

  1. Effect of inlet fuel type on the degradation of Ni/YSZ anode of solid oxide fuel cell by carbon deposition

    Directory of Open Access Journals (Sweden)

    Suttichai Assabumrungrat

    2006-11-01

    Full Text Available According to the high operating temperature of Solid Oxide Fuel Cell (SOFC (700-1100ºC, it is known that some hydrocarbon fuels can be directly used as inlet fuel instead of hydrogen by feeding straight to the anode. This operation is called a direct internal reforming SOFC (DIR-SOFC. However, the major difficulty of this operation is the possible degradation of anode by the carbon deposition, as the carbon species are easily formed. In the present work, the effect of inlet fuel (i.e. H2, synthesis gas (H2+CO, CH4, CH4+H2O, CH3OH+H2O, and C2H5OH+H2O on the degradation of nickel cermet (Ni/YSZ, which is the most common anode material of SOFC, was studied.It was found from the work that hydrogen and synthesis gas (CO+H2 are proper to be used as direct inlet fuels for DIR-SOFC with Ni/YSZ anode, since the carbon formation on Ni/YSZ occurred in the small quantity. The mixture of methane and steam (CH4+H2O can also be used as the inlet feed, but the H2O/CH4 ratio plays an important role. In contrast, pure methane (CH4, methanol with steam (CH3OH+H2O and ethanol with steam (C2H5OH+H2O are not suitable for using as direct inlet fuel for DIR-SOFC with Ni/YSZ anode even the higher H2O/CH3OH and H2O/C2H5OH ratios were applied.

  2. Achieving High Efficiency and Eliminating Degradation in Solid Oxide Electrochemical Cells Using High Oxygen-Capacity Perovskite.

    Science.gov (United States)

    Jun, Areum; Kim, Junyoung; Shin, Jeeyoung; Kim, Guntae

    2016-09-26

    Recently, there have been efforts to use clean and renewable energy because of finite fossil fuels and environmental problems. Owing to the site-specific and weather-dependent characteristics of the renewable energy supply, solid oxide electrolysis cells (SOECs) have received considerable attention to store energy as hydrogen. Conventional SOECs use Ni-YSZ (yttria-stabilized zirconia) and LSM (strontium-doped lanthanum manganites)-YSZ as electrodes. These electrodes, however, suffer from redox-instability and coarsening of the Ni electrode along with delamination of the LSM electrode during steam electrolysis. In this study, we successfully design and fabricate highly efficient SOECs using layered perovskites, PrBaMn2 O5+δ (PBM) and PrBa0.5 Sr0.5 Co1.5 Fe0.5 O5+δ (PBSCF50), as both electrodes for the first time. The SOEC with layered perovskites as both-side electrodes shows outstanding performance, reversible cycling, and remarkable stability over 600 hours. PMID:27604172

  3. A Numerical Solution Routine for Investigating Oxidation-Induced Strength Degradation Mechanisms in SiC/SiC Composites

    Science.gov (United States)

    Sullivan, Roy M.

    2015-01-01

    The stress rupture strength of silicon carbide fiber-reinforced silicon carbide (SiCSiC) composites with a boron nitride (BN) fiber coating decreases with time within the intermediate temperature range of 700-950 C. Various theories have been proposed to explain the cause of the time dependent stress rupture strength. Some previous authors have suggested that the observed composite strength behavior is due to the inherent time dependent strength of the fibers, which is caused by the slow growth of flaws within the fibers. Flaw growth is supposedly enabled by oxidation of free carbon at the grain boundaries. The objective of this paper is to investigate the relative significance of the various theories for the time-dependent strength of SiCSiC composites. This is achieved through the development of a numerically-based progressive failure analysis routine and through the application of the routine to simulate the composite stress rupture tests. The progressive failure routine is a time marching routine with an iterative loop between a probability of fiber survival equation and a force equilibrium equation within each time step. Failure of the composite is assumed to initiate near a matrix crack and the progression of fiber failures occurs by global load sharing. The probability of survival equation is derived from consideration of the strength of ceramic fibers with randomly occurring and slow growing flaws as well as the mechanical interaction between the fibers and matrix near a matrix crack. The force equilibrium equation follows from the global load sharing presumption. The results of progressive failure analyses of the composite tests suggest that the relationship between time and stress-rupture strength is attributed almost entirely to the slow flaw growth within the fibers. Although other mechanisms may be present, they appear to have only a minor influence on the observed time dependent behavior.

  4. Occupational exposure to coal tar pitch volatiles, benzo/a/pyrene and dust in tyre production.

    Science.gov (United States)

    Rogaczewska, T; Ligocka, D

    1994-01-01

    Occupational exposure to coal tar pitch volatiles (CTPVs), benzo/a/pyrene (BaP) and dust was evaluated by means of individual measurements carried out in 80 workers and by stationary measurements on 16 work-posts in two divisions of the tyre producing plant. Dust and coal tar pitch volatiles concentrations in the air were determinated by the gravimetric method, measured, in the case of CPTVs, benzene-soluble fraction (BSF) with ultrasonic extraction. Benzo/a/pyrene analysis was performed using high performance liquid chromato-graphy (HPLC) with a spectrofluorimetric detector. It was found that nearly all personal sampling results for BaP were within the range 90%) which exceeded the admissible value (4 mg/m3) was found mainly only in the workers of the Semiproducts Division at some work-posts.

  5. Electro-Fenton and photoelectro-Fenton degradations of the drug beta-blocker propranolol using a Pt anode: Identification and evolution of oxidation products

    Energy Technology Data Exchange (ETDEWEB)

    Isarain-Chavez, Eloy; Cabot, Pere Lluis; Centellas, Francesc; Rodriguez, Rosa Maria; Arias, Conchita; Garrido, Jose Antonio [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.edu [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2011-01-30

    The beta-blocker propranolol hydrochloride has been degraded by electrochemical advanced oxidation processes like electro-Fenton (EF) and photoelectro-Fenton (PEF) using a single cell with a Pt anode and an air diffusion cathode (ADE) for H{sub 2}O{sub 2} electrogeneration and a combined system containing the above Pt/ADE pair coupled in parallel to a Pt/carbon-felt (CF) cell. Organics are mainly oxidized with hydroxyl radical ({center_dot}OH) formed from Fenton's reaction between added Fe{sup 2+} and electrogenerated H{sub 2}O{sub 2}. The PEF treatment in Pt/ADE-Pt/CF system yields almost total mineralization because {center_dot}OH production is enhanced by Fe{sup 2+} regeneration from Fe{sup 3+} reduction at the CF cathode and Fe(III) complexes with generated carboxylic acids are rapidly photodecarboxylated under UVA irradiation. Lower mineralization degree is found for PEF in Pt/ADE cell due to the little influence of UVA light on Fe{sup 2+} regeneration. The homologous EF processes are much less potent as a result of the persistence of Fe(III)-carboxylate complexes. Aromatic intermediates such as 1-naphthol, 1,4-naphthoquinone and phthalic acid and generated carboxylic acids such as pyruvic, glycolic, malonic, maleic, oxamic, oxalic and formic are identified. While chloride ion remains stable, NH{sub 4}{sup +} and NO{sub 3}{sup -} ions are released to the medium. A reaction sequence for propranolol hydrochloride mineralization is proposed.

  6. Sodium chloride stress induces nitric oxide accumulation in root tips and oil body surface accompanying slower oleosin degradation in sunflower seedlings.

    Science.gov (United States)

    David, Anisha; Yadav, Sunita; Bhatla, Satish C

    2010-12-01

    Present work highlights the involvement of endogenous nitric oxide (NO) in sodium chloride (NaCl)-induced biochemical regulation of seedling growth in sunflower (Helianthus annuus L., cv. Morden). The growth response is dependent on NaCl concentration to which seedlings are exposed, they being tolerant to 40 mM NaCl and showing a reduction in extension growth at 120 mM NaCl. NaCl sensitivity of sunflower seedlings accompanies a fourfold increase in Na(+) /K(+) ratio in roots (as compared to that in cotyledons) and rapid transport of Na(+) to the cotyledons, thereby enhancing Na(+) /K(+) ratio in cotyledons as well. A transient increase in endogenous NO content, primarily contributed by putative NOS activity in roots of 4-day-old seedlings subjected to NaCl stress and the relative reduction in Na(+) /K(+) ratio after 4 days, indicates that NO regulates Na(+) accumulation, probably by affecting the associated transporter proteins. Root tips exhibit an early and transient enhanced expression of 4,5-diaminofluorescein diacetate (DAF-2DA) positive NO signal in the presence of 120 mM NaCl. Oil bodies from 2-day-old seedling cotyledons exhibit enhanced localization of NO signal in response to 120 mM NaCl treatment, coinciding with a greater retention of the principal oil body membrane proteins, i.e. oleosins. Abolition of DAF positive fluorescence by the application of specific NO scavenger [2-phenyl-4,4,5,5-tetramethyllimidazoline-1-oxyl-3-oxide (PTIO)] authenticates the presence of endogenous NO. These novel findings provide evidence for a possible protective role of NO during proteolytic degradation of oleosins prior to/accompanying lipolysis.

  7. Rapid liquid chromatography–tandem mass spectrometry analysis of 4-hydroxynonenal for the assessment of oxidative degradation and safety of vegetable oils

    Energy Technology Data Exchange (ETDEWEB)

    Gabbanini, Simone; Matera, Riccardo [BeC S.r.l., R& D Division, Via C. Monteverdi 49, 47122 Forlì (Italy); Valvassori, Alice [University of Bologna, Department of Chemistry “G. Ciamician”, Via S. Giacomo 11, 40126 Bologna (Italy); Valgimigli, Luca, E-mail: luca.valgimigli@unibo.it [University of Bologna, Department of Chemistry “G. Ciamician”, Via S. Giacomo 11, 40126 Bologna (Italy)

    2015-04-15

    Highlights: • A novel method for the UPLC–MS/MS analysis of 4-HNE is described. • The method allows complete analysis of a vegetable oil in 21 min with LOD ≤ 7 ng g{sup −1}. • Excellent recovery from lipid matrices without deuterium-labeled internal standards. • Requires straightforward sample manipulation and routine equipment. • Allows fast, reliable, cost-effective assessment of safety and quality of oils. - Abstract: A novel method for the UHPLC–MS/MS analysis of (E)-4-hydroxynonenal (4-HNE) is described. The method is based on derivatization of 4-HNE with pentafluorophenylhydrazine (1) or 4-trifluoromethylphenylhydrazine (2) in acetonitrile in the presence of trifluoroacetic acid as catalyst at room temperature and allows complete analysis of one sample of vegetable oil in only 21 min, including sample preparation and chromatography. The method involving hydrazine 1, implemented in an ion trap instrument with analysis of the transition m/z 337 → 154 showed LOD = 10.9 nM, average accuracy of 101% and precision ranging 2.5–4.0% RSD intra-day (2.7–4.1% RSD inter-day), with 4-HNE standard solutions. Average recovery from lipid matrices was 96.3% from vaseline oil, 91.3% from sweet almond oil and 105.3% from olive oil. The method was tested on the assessment of safety and oxidative degradation of seven samples of dietary oil (soybean, mixed seeds, corn, peanut, sunflower, olive) and six cosmetic-grade oils (avocado, blackcurrant, apricot kernel, echium, sesame, wheat germ) and effectively detected increased 4-HNE levels in response to chemical (Fenton reaction), photochemical, or thermal stress and aging, aimed at mimicking typical oxidation associated with storage or industrial processing. The method is a convenient, cost-effective and reliable tool to assess quality and safety of vegetable oils.

  8. Rapid liquid chromatography–tandem mass spectrometry analysis of 4-hydroxynonenal for the assessment of oxidative degradation and safety of vegetable oils

    International Nuclear Information System (INIS)

    Highlights: • A novel method for the UPLC–MS/MS analysis of 4-HNE is described. • The method allows complete analysis of a vegetable oil in 21 min with LOD ≤ 7 ng g−1. • Excellent recovery from lipid matrices without deuterium-labeled internal standards. • Requires straightforward sample manipulation and routine equipment. • Allows fast, reliable, cost-effective assessment of safety and quality of oils. - Abstract: A novel method for the UHPLC–MS/MS analysis of (E)-4-hydroxynonenal (4-HNE) is described. The method is based on derivatization of 4-HNE with pentafluorophenylhydrazine (1) or 4-trifluoromethylphenylhydrazine (2) in acetonitrile in the presence of trifluoroacetic acid as catalyst at room temperature and allows complete analysis of one sample of vegetable oil in only 21 min, including sample preparation and chromatography. The method involving hydrazine 1, implemented in an ion trap instrument with analysis of the transition m/z 337 → 154 showed LOD = 10.9 nM, average accuracy of 101% and precision ranging 2.5–4.0% RSD intra-day (2.7–4.1% RSD inter-day), with 4-HNE standard solutions. Average recovery from lipid matrices was 96.3% from vaseline oil, 91.3% from sweet almond oil and 105.3% from olive oil. The method was tested on the assessment of safety and oxidative degradation of seven samples of dietary oil (soybean, mixed seeds, corn, peanut, sunflower, olive) and six cosmetic-grade oils (avocado, blackcurrant, apricot kernel, echium, sesame, wheat germ) and effectively detected increased 4-HNE levels in response to chemical (Fenton reaction), photochemical, or thermal stress and aging, aimed at mimicking typical oxidation associated with storage or industrial processing. The method is a convenient, cost-effective and reliable tool to assess quality and safety of vegetable oils

  9. Oxidation-reduction potentials and ionization states of extracellular peroxidases from the lignin-degrading fungus Phanerochaete chrysosporium

    International Nuclear Information System (INIS)

    The oxidation-reduction potentials of lignin peroxidase isozymes H1, H2, H8, and H10 as well as the Mn-dependent peroxidase isozymes H3 and H4 are reported. The potentiometric titrations involving the ferrous and ferric states of the enzyme had Nernst plots indicating single-electron transfer. The Em7 values of lignin peroxidase isozymes H1, H2, H8, and H10 are -142, -135, -137, and -127 mV versus standard hydrogen electrode, respectively. The Em7 values for the Mn-dependent peroxidase isozymes H3 and H4 are -88 and -93 mV versus standard hydrogen electrode, respectively. The midpoint potential of H1, H8, and H4 remained unchanged in the presence of their respective substrates, veratryl alcohol and Mn(II). The midpoint potential between the ferric and ferrous forms of isozymes H1 and H4 exhibited a pH-dependent change between pH 3.5 and pH 6.5. These results indicate that the reductive half-reaction of the enzymes is the following: ferric peroxidase + le- + H+----ferrous peroxidase. Above pH 6.5, the effect of pH on the midpoint potential is diminished and indicates that an ionization with an apparent pKa equal to approximately 6.6-6.7 occurs in the reduced form of the enzymes. A heme-linked ionization group in the ferrous form of the enzymes was confirmed by studying the effect of pH on the absorption spectra of isozymes H1 and H4. These spectrophotometric pH titration experiments confirmed the electrochemical results indicating pKa values of 6.59 and 6.69 for reduced isozymes H1 and H4, respectively. These results indicate the presence of a heme-linked ionization of an amino acid in the reduced form of the lignin peroxidase isozymes similar to that of other plant peroxidases

  10. 羟基氧化铁催化臭氧氧化降解苯胺废水%Degradation of aniline Wastewater by hydroxyl iron oxide catalytic ozone oxidation

    Institute of Scientific and Technical Information of China (English)

    林继辉; 蒋联规; 曾飞虎; 黄先锋

    2012-01-01

    以实验室制备的羟基氧化铁(FeOOH)为催化剂催化臭氧氧化处理苯胺废水,对比催化臭氧氧化与单独臭氧降解苯胺的效率,实验结果表明,FeOOH催化臭氧氧化能加快对苯胺的降解速率,并且矿化程度高.说明FeOOH对臭氧氧化水中的苯胺具有明显的催化作用.探讨了氧气的进气流量、苯胺的初始浓度、水溶液的pH、催化剂的投加量等因素对催化氧化苯胺的影响.研究表明:氧气的进气流量为30L/h、初始浓度300mg/L时、pH值7.3、催化剂的投加量为2g/L、反应15min后,苯胺的去除率可达98.2%,COD的去除率可达70%.在催化体系中加入自由基捕获剂叔丁醇后,催化臭氧氧化反应明显受到抑制,间接证明了FeOOH催化臭氧氧化苯胺遵循自由基反应机理.%By the laboratory preparation of hydroxyl ferric oxide (FeOOH) as catalyst 03 catalytic oxidation wastewater treatment aniline, the contrast of 03 catalytic and individual ozone of aniline degradation efficiency is made. The experimental results show that FeOOH 03 catalytic can accelerate the degradation rate of aniline, and a high degree of mineralization. It also proves that the FeOOH to ozone oxidation of aniline in water has the obvious catalytic activity. The paper discusses the oxygen intake flow, aniline initial concentration, the solution of the catalyst pH and the dosing quantity of factors catalytic oxidation of aniline influence. Research shows that: oxygen intake flow for 30 L/h, initial concentration 300 mg/L, pH value of 7.3, catalyst dosing quantity for 2 g/L, reaction after 15 min to the removal rate of aniline can reach 98.2%. The COD removal rate can amount to 70%. Through the process of free radicals in catalytic to capture agent after uncle butanol, it showed significant inhibitory catalytic oxidation reaction ozone, which indirectly proves that the FeOOH 03 catalytic oxidation aniline follows the free radicals reaction mechanism.

  11. Benzo(a)pyrene activation and detoxification by human pulmonary alveolar macrophages and lymphocytes

    International Nuclear Information System (INIS)

    Comparisons of pulmonary alveolar macrophages and circulating lymphocytes from five smokers and five nonsmokers for their ability to metabolize benzo(a)pyrene as determined by high pressure liquid chromatography were carried out. Utilizing this approach, further investigation of activation and detoxification by several human cell types could provide the basis for more precise and comprehensive studies of carcinogen and drug metabolism in the human lung, and for a better assessment of cancer risk in selected populations

  12. Benzo(a)pyrene diolepoxide-DNA adducts detected by synchronous fluorescence spectrophotometry.

    OpenAIRE

    Vahakangas, K.; Trivers, G; Rowe, M.; Harris, C. C.

    1985-01-01

    Using benzo(a)pyrene (BP) as a model carcinogen we are currently applying a fluorescence technique to detect the very low levels of carcinogen-DNA adducts in human populations due to environmental exposure. In synchronous fluorescence spectrophotometry for detection of BP-diol epoxide-DNA, excitation and emission wavelengths are scanned simultaneously with a fixed wavelength difference (delta lambda) of 34 nm. Compared to conventional fluorescence methods only one peak emerges because excitat...

  13. Micropollutant degradation, bacterial inactivation and regrowth risk in wastewater effluents: Influence of the secondary (pre)treatment on the efficiency of Advanced Oxidation Processes.

    Science.gov (United States)

    Giannakis, Stefanos; Voumard, Margaux; Grandjean, Dominique; Magnet, Anoys; De Alencastro, Luiz Felippe; Pulgarin, César

    2016-10-01

    In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondary treatment systems present in the wastewater treatment plant of Vidy, Lausanne (Switzerland). 5 AOPs after two biological treatment methods (conventional activated sludge and moving bed bioreactor) and a physiochemical process (coagulation-flocculation) were tested in laboratory scale. The dependence among AOPs efficiency and secondary (pre)treatment was estimated by following the bacterial concentration i) before secondary treatment, ii) after the different secondary treatment methods and iii) after the various AOPs. Disinfection and post-treatment bacterial regrowth were the evaluation indicators. The order of efficiency was Moving Bed Bioreactor > Activated Sludge > Coagulation-Flocculation > Primary Treatment. As far as the different AOPs are concerned, the disinfection kinetics were: UVC/H2O2 > UVC and solar photo-Fenton > Fenton or solar light. The contextualization and parallel study of microorganisms with the micropollutants of the effluents revealed that higher exposure times were necessary for complete degradation compared to microorganisms for the UV-based processes and inversed for the Fenton-related ones. Nevertheless, in the Fenton-related systems, the nominal 80% removal of micropollutants deriving from the Swiss legislation, often took place before the elimination of bacterial regrowth risk.

  14. Micropollutant degradation, bacterial inactivation and regrowth risk in wastewater effluents: Influence of the secondary (pre)treatment on the efficiency of Advanced Oxidation Processes.

    Science.gov (United States)

    Giannakis, Stefanos; Voumard, Margaux; Grandjean, Dominique; Magnet, Anoys; De Alencastro, Luiz Felippe; Pulgarin, César

    2016-10-01

    In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondary treatment systems present in the wastewater treatment plant of Vidy, Lausanne (Switzerland). 5 AOPs after two biological treatment methods (conventional activated sludge and moving bed bioreactor) and a physiochemical process (coagulation-flocculation) were tested in laboratory scale. The dependence among AOPs efficiency and secondary (pre)treatment was estimated by following the bacterial concentration i) before secondary treatment, ii) after the different secondary treatment methods and iii) after the various AOPs. Disinfection and post-treatment bacterial regrowth were the evaluation indicators. The order of efficiency was Moving Bed Bioreactor > Activated Sludge > Coagulation-Flocculation > Primary Treatment. As far as the different AOPs are concerned, the disinfection kinetics were: UVC/H2O2 > UVC and solar photo-Fenton > Fenton or solar light. The contextualization and parallel study of microorganisms with the micropollutants of the effluents revealed that higher exposure times were necessary for complete degradation compared to microorganisms for the UV-based processes and inversed for the Fenton-related ones. Nevertheless, in the Fenton-related systems, the nominal 80% removal of micropollutants deriving from the Swiss legislation, often took place before the elimination of bacterial regrowth risk. PMID:27403873

  15. The mechanism of degradation of bisphenol A using the magnetically separable CuFe2O4/peroxymonosulfate heterogeneous oxidation process.

    Science.gov (United States)

    Xu, Yin; Ai, Jia; Zhang, Hui

    2016-05-15

    The removal of bisphenol A (BPA) in aqueous solution by an oxidation process involving peroxymonosulfate (PMS) activated by CuFe2O4 magnetic nanoparticles (MNPs) is reported herein. The effects of PMS concentration, CuFe2O4 dosage, initial pH, initial BPA concentration, catalyst addition mode, and anions (Cl(-), F(-), ClO4(-) and H2PO4(-)) on BPA degradation were investigated. Results indicate that nearly complete removal of BPA (50 mg/L) within 60 min and 84.0% TOC removal in 120 min could be achieved at neutral pH by using 0.6 g/L CuFe2O4 MNPs and 0.3 g/L PMS. The generation of reactive radicals (mainly hydroxyl radicals) was confirmed using electron paramagnetic resonance (EPR). Possible mechanisms on the radical generation from CuFe2O4/PMS system are proposed based on the results of radical identification tests and XPS analysis. The lack of inhibition of the reaction by free radical scavengers such as methanol and tert-butyl alcohol suggests that these species may not be generated in the bulk solution, and methylene blue probe experiments confirm that this process does not involve free radical generation. Surface-bound, rather than free radicals generated by a surface catalyzed-redox cycle involving both Fe(III) and Cu(II), are postulated to be responsible for the mineralization of bisphenol A. PMID:26875144

  16. Enhanced photocatalytic activity of TiO2-impregnated with MgZnAl mixed oxides obtained from layered double hydroxides for phenol degradation

    Science.gov (United States)

    de Almeida, Marciano Fabiano; Bellato, Carlos Roberto; Mounteer, Ann Honor; Ferreira, Sukarno Olavo; Milagres, Jaderson Lopes; Miranda, Liany Divina Lima

    2015-12-01

    A series of TiO2/MgZnAl photocatalysts were successfully synthesized from ternary (Mg, Zn and Al) layered double hydroxides impregnated with TiO2 nanoparticles by the co-precipitation method at variable pH with different Zn2+/Mg2+ molar ratios. The composite photocatalysts were calcined at 500 °C resulting in the incorporation of oxide zinc, in the calcined MgZnAl LDH structure. Synergistic effect between ZnO and TiO2 lead to significant enhancement of TiO2/MgZnAl photocatalytic activity. Composite photocatalysts were characterized by ICP-MS, N2 adsorption-desorption, XRD, SEM, EDS, IR and UV-vis DRS. Phenol in aqueous solution (50 mg/L) was used as a model compound for evaluation of UV-vis (filter cut-off for λ > 300 nm) photocatalytic activity. The most efficient photocatalyst composite was obtained at a 5% Zn2+/Mg2+ molar ratio, in the catalyst identified as TiO2/MgZnAl-5. This composite catalyst had high photocatalytic activity, completely destroying phenol and removing 80% of total organic carbon in solution after 360 min. The TiO2/MgZnAl-5 catalyst remained relatively stable, presenting a 15% decrease in phenol degradation efficiency after five consecutive photocatalytic cycles.

  17. Mixed metal oxide nanocomposites derived from layered double hydroxides as photocatalysts for C.I. Basic Blue 3 degradation under UV light

    Energy Technology Data Exchange (ETDEWEB)

    Rezvani, Z.; Sarkarat, M. [Department of Chemistry, Faculty of Basic Sciences, Azarbaijan University of Shahid Madani,Tabriz (Iran, Islamic Republic of); Khataee, A.R. [Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz (Iran, Islamic Republic of); Nejati, K. [Chemistry Department, Payame Noor University, Tehran (Iran, Islamic Republic of)

    2012-11-15

    In this research we report synthesis of the heterostructure Mg-Al-Zn mixed metal oxide (ZnO/MMO) nanocomposite photocatalysts derived from Zn(OH){sub 2}/Mg-Al-layered double hydroxides (ZLDHs) precursors. The obtained samples were characterized by the X-ray diffraction (XRD), FT-IR, BET surface area, ICP and TG/DTG methods. The chemical compositions and morphology of the synthesized materials were investigated by the energy dispersive X-ray analysis (EDX) and the transmission electron microscopy (TEM). The results reveal that at the reaction time 96 h, ZLDH has the highest crystalinity which was confirmed by the X-ray diffraction spectra. The calcined samples at 500, 600 and 700 C for 4 h show that the crystallinity of the nanocomposite improves with the increase of calcination temperature. The photocatalytic activities of synthesized nanocomposites were compared for the degradation of C. I. Basic Blue 3 (BB3) dye under UV illumination in aqueous solution. Among the synthesized nanocomposites, ZnO/MMO calcined at 700 C shows the highest efficiency towards the removal of dye. The effect of UV illumination on the stability of ZnO in ZnO/MMO nanocomposite and pure ZnO was also investigated. The results showed that the photostability of ZnO in ZnO/MMO nanocomposite is increased compared to the pure ZnO. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Preparation of flower-like TiO2 sphere/reduced graphene oxide composites for photocatalytic degradation of organic pollutants

    Science.gov (United States)

    Kim, Tae-Woong; Park, Mira; Kim, Hak Yong; Park, Soo-Jin

    2016-07-01

    In this study, novel flower-like TiO2 sphere (FTS)/reduced graphene oxide (rGO) composites (FTS-G) were synthesized via a hydrothermal method. The photocatalytic performance of the FTS-G composites was evaluated through the photodegradation of rhodamine B (Rh B) and trichloroethylene (TCE) under simulated solar light irradiation. The rGO to FTS ratio in the composites significantly affected photocatalytic activity. The photocatalytic activities of FTS-Gs in the degradation of Rh B and TCE were superior to that of pure FTS. Of all the FTS-G composites tested, FTS-G with 1 wt% rGO (FTS-G-1) had the greatest photocatalytic activity, while FTS-G composites with rGO contents over 1 wt% had lower photocatalytic activities. Additionally, it is expected that the synthesis of FTS with a high specific surface area and well-developed pore structure and simultaneous conversion of GO to graphene-like rGO without the use of strong reducing agents could be a promising strategy to prepare other carbon-based flower-like TiO2 sphere composite photocatalysts.

  19. Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.

    Science.gov (United States)

    Mousset, Emmanuel; Huguenot, David; van Hullebusch, Eric D; Oturan, Nihal; Guibaud, Gilles; Esposito, Giovanni; Oturan, Mehmet A

    2016-04-01

    The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (p

  20. How do polymers degrade?

    Science.gov (United States)

    Lyu, Suping

    2011-03-01

    Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.

  1. Decolorization of dark brown colored coffee effluent using zinc oxide particles: the role of dissolved oxygen in degradation of colored compounds.

    Science.gov (United States)

    Satori, Hirotaka; Kawase, Yoshinori

    2014-06-15

    The degradation of model dark brown colored coffee effluent using photocatalyst zinc oxide (ZnO) has been systematically studied by varying ZnO dosage from 0 to 4000 mg L(-1), coffee loading from 0 to 90 mg L(-1) and intensity of UV light having the radiation peak at 352 nm from 0 to 18 W(m-lamp length)(-1). Almost complete decolorization was achieved after 180 min for the initial coffee concentration of 50 mg L(-1) with ZnO dosage of 3000 mg L(-1) and three UV lamps. The dissolved oxygen (DO) largely affected the photodecolorization process. Without air sparging or with oxygen supply only through the free-surface, the DO concentration significantly decreased during the initial decolorization process and then increased to the saturated DO concentration after about 80% decolorization was achieved. Under the anoxic condition with nitrogen gas sparging, the efficient color removal was not obtained unlike the decolorization without air sparging or under the oxic condition with air sparging. These findings suggest that the change in DO concentration was controlled by the oxygen consumption for the formation of oxygen adduct intermediates such as organoperoxy radicals. The mineralization rate of model coffee effluent was rather slow as compared with the decolorization rate and it was insignificantly affected by anoxic and oxic conditions. The present results indicate that ZnO photocatalyst has potential for treatment of coffee processing wastewaters. PMID:24698992

  2. Size-Controlled TiO2 nanocrystals with exposed {001} and {101} facets strongly linking to graphene oxide via p-Phenylenediamine for efficient photocatalytic degradation of fulvic acids.

    Science.gov (United States)

    Yan, Wen-Yuan; Zhou, Qi; Chen, Xing; Yang, Yong; Zhang, Yong; Huang, Xing-Jiu; Wu, Yu-Cheng

    2016-08-15

    Photocatalytic degradation is one of the most promising methods for removal of fulvic acids (FA), which is a typical category of natural organic contamination in groundwater. In this paper, TiO2/graphene nanocomposites (N-RGO/TiO2) were prepared via simple chemical functionalization and one-step hydrothermal method for efficient photodegradation of FA under illumination of a xenon lamp as light source. Here, p-phenylenediamine was used as not only the linkage chemical agent between TiO2 nanocrystals and graphene, but also the nitrogen dopant for TiO2 nanocrystals and graphene. During the hydrothermal process, facets of TiO2 nanocrystals were modulated with addition of HF, and sizes of TiO2 nanocrystals were controlled by the contents of graphene oxide functionalized with p-phenylenediamine (RGO-NH2). The obtained N-RGO/TiO2 nanocomposites exhibited a much higher photocatalytic activity and stability for degradation of methyl blue (MB) and FA compared with other TiO2 samples under xenon lamp irradiation. For the third cycle, the 10wt%N-RGO/TiO2 catalyst maintains high photoactivity (87%) for the degradation of FA, which is much better than the TiO2-N/F (61%) in 3h. This approach supplies a new strategy to design and synthesize metal oxide and graphene oxide nanocomposites with highly efficient photocatalytic performance. PMID:27107234

  3. Effect of various chemicals on the metabolism of benzo(a)pyrene by cultured rat colon

    DEFF Research Database (Denmark)

    1977-01-01

    The effect of various co- and anti-carcinogens of colon carcinogenesis on the metabolism of benzo(a)pyrene (BP) in cultured rat colon is reported. Rat colon enzymatically converted BP into metabolites which bind to cellular macromolecules i.e., DNA and protein. Activity of aryl hydrocarbon...... hydroxylase (AHH) activity and binding levels of BP to macromolecules were higher in the descending colon when compared to other segments. The major metabolites of BP, extractable with ethylacetate, were quinones, tetrols, 7,8-diol and a peak containing 9,10-dihydroxy-9,10-dihydrobenzo(a)pyrene and 7...

  4. Determination of the level of benzo[a]pyrene in fatty foods and food supplements

    OpenAIRE

    Van Der Wielen-Hustinx, Jacqueline Claire Agnes; Jansen, John; Martena, Martijn J.; De Groot, Henk; In T Veld, Paul

    2006-01-01

    Abstract A routine method was developed for the quantification of benzo[a]pyrene (BaP) in edible oils and food supplements. BaP is often taken as an indicator of the presence of polycyclic aromatic hydrocarbons. The method consists of on-line LC-clean up followed by injection to an HPLC-system connected with fluorescence detection. The method has good performance characteristics and gave good results in proficiency tests. From 2002 to 2004 about 1350 samples, oils and food supp...

  5. Benzo(a)pyrene Induced p53 Mediated Male Germ Cell Apoptosis: Synergistic Protective Effects of Curcumin and Resveratrol.

    Science.gov (United States)

    Banerjee, Bhaswati; Chakraborty, Supriya; Ghosh, Debidas; Raha, Sanghamitra; Sen, Parimal C; Jana, Kuladip

    2016-01-01

    Benzo(a)pyrene (B(a)P) is an environmental toxicant that induces male germ cell apoptosis. Curcumin and resveratrol are phytochemicals with cytoprotective and anti-oxidative properties. At the same time resveratrol is also a natural Aryl hydrocarbon Receptor (AhR) antagonist. Our present study in isolated testicular germ cell population from adult male Wistar rats, highlighted the synergistic protective effect of curcumin and resveratrol against B(a)P induced p53 mediated germ cell apoptosis. Curcumin-resveratrol significantly prevented B(a)P induced decrease in sperm cell count and motility, as well as increased serum testosterone level. Curcumin-resveratrol co-treatment actively protected B(a)P induced testicular germ cell apoptosis. Curcumin-resveratrol co-treatment decreased the expression of pro-apoptotic proteins like cleaved caspase 3, 8 and 9, cleaved PARP, Apaf1, FasL, tBid. Curcumin-resveratrol co-treatment decreased Bax/Bcl2 ratio, mitochondria to cytosolic translocation of cytochrome c and activated the survival protein Akt. Curcumin-resveratrol decreased the expression of p53 dependent apoptotic genes like Fas, FasL, Bax, Bcl2, and Apaf1. B(a)P induced testicular reactive oxygen species (ROS) generation and oxidative stress were significantly ameliorated with curcumin and resveratrol. Curcumin-resveratrol co-treatment prevented B(a)P induced nuclear translocation of AhR and CYP1A1 (Cytochrome P4501A1) expression. The combinatorial treatment significantly inhibited B(a)P induced ERK 1/2, p38 MAPK and JNK 1/2 activation. B(a)P treatment increased the expression of p53 and its phosphorylation (p53 ser 15). Curcumin-resveratrol co-treatment significantly decreased p53 level and its phosphorylation (p53 ser 15). The study concludes that curcumin-resveratrol synergistically modulated MAPKs and p53, prevented oxidative stress, regulated the expression of pro and anti-apoptotic proteins as well as the proteins involved in B(a)P metabolism thus protected germ

  6. Co-precipitation synthesis of nano-composites consists of zinc and tin oxides coatings on glass with enhanced photocatalytic activity on degradation of Reactive Blue 160 KE2B.

    Science.gov (United States)

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-25

    Nano-composite containing zinc oxide-tin oxide was obtained by a facile co-precipitation route using tin chloride tetrahydrate and zinc chloride as precursors and coated on glass by Doctor Blade deposition. The crystalline structure and morphology of composites were evaluated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The XRD results showed peaks relative to zinc oxide with hexagonal wurtzite structure and tin oxide with tetragonal structure. FESEM observations showed that the nano-composite consisted of aggregates of particles with an average particle size of 18 nm. The photocatalytic activity of the pure SnO2, pure ZnO, ZnSnO3-Zn2SnO4 and ZnO-SnO2 nano-structure thin films was examined using the degradation of a textile dye Reactive Blue 160 (KE2B). ZnO-SnO2 nano-composite showed enhanced photo-catalytic activity than the pure zinc oxide and tin oxide. The enhanced photo-catalytic activity of the nano-composite was ascribed to an improved charge separation of the photo-generated electron-hole pairs. PMID:25265524

  7. Performance of Polymeric Metalloporphyrins for Photocatalytic Oxidative Degradation of Wasted-Water%高分子金属卟啉光催化氧化处理废水

    Institute of Scientific and Technical Information of China (English)

    金星龙; 朱琨; 房彦军; 杨瑞强; 陈慧

    2001-01-01

    将高分子金属卟啉聚中位四(4,4’-联苯二磺酰基)氧基苯基钴卟啉用于多相光催化体系,在温和条件下成功地降解了有机染料吖啶橙.实验结果表明,降解反应符合一级动力学方程lnct=2.52052-0.565 46t(R=-0.997 04),经8h的反应以后,染料溶液完全褪色.将此光催化剂用于混合染料、染料废水、化工厂废水及生活污水的处理,脱色率可达68%,COD去除率可达58%.通过对高压汞灯、碘钨灯和自然光等各种光源进行比较,发现在太阳光照射下,金属卟啉光催化氧化降解有机污染物的效率更高、速度更快、降解更完全.%In heterogeneous phot ocatalytic oxidation system, acridineorange (AO) was degraded successfully by polymeric metalloporphyrin Co [meso-tetra (4, 4'-biphenylbisulfonyl) phenylporphyrin] ( PCoTBPBSOPP) under mild conditions. The results indicated that the photodegra dation of AO obeys the first order law with equation as lnct=2.520 52-0.565 46t (R=-0.997?04). AO was decolored and decomposed completel y after 8 h. Since PCoTBPBSOPP was applied to treat textile, industrial and dome stic wasted-water, it was found that the average decolorization ratio of the dyes wasted-water is up to 68% and the average removal of COD re aches 58%. By comparison with high-pressure mercury lamp (HPML), iodine tungste n lamp (ITL) and natural sunlight(NSL), AO can be decomposed rapidly under irradiatio n with NSL. It is proved that the polymeric metalloporphyrins have a potential effective application in treating the wasted-water under natural conditons.

  8. Effects of a vanadium post-metallocene catalyst-induced polymer backbone inhomogeneity on UV oxidative degradation of the resulting polyethylene film

    KAUST Repository

    Atiqullah, M.

    2012-07-01

    A Group 5 post-metallocene precatalyst, (ONO)VCl(THF) 2 (ONO = a bis(phenolate)pyridine LX 2 pincer ligand), activated with modified methylaluminoxane (MMAO-3A) produced a linear ethylene homopolymer (nm-HomoPE)and an unusual inhomogeneous copolymer (nm-CopolyPE) with 1-hexene having very low backbone unsaturation. The nm-CopolyPE inhomogeneity was reflected in the distributions of short chain branches, 1-hexene composition, and methylene sequence length. The 1-hexene incorporation into the polyethylene backbone strongly depended on the molecular weight of the growing polymer chain. (ONO)VCl(THF) 2, because of site diversity and easier removal of a tertiary (vs. a secondary) hydrogen, produced a skewed short chain branching (SCB) profile, incorporating 1-hexene more efficiently in the low molecular weight region than in the high molecular weight region. The significant decrease in molecular weight by 1-hexene showed that the (ONO)VCl(THF) 2 catalytic sites were also highly responsive to chain-transfer directly to 1-hexene itself, producing vinyl and trans-vinylene termini. Subsequently, the effect of backbone inhomogeneity on the UV oxidative degradation of films made from both polyethylenes was investigated. The major functional group accumulated in the branched nm-CopolyPE film was carbonyl followed by carboxyl, then vinyl/ester, whereas that in the linear nm-HomoPE film was carboxyl. However, (carbonyl, carboxyl, vinyl, and ester) nm-CopolyPE film >> (carboxyl) nm-HomoPE film). The distributions of the tertiary C-H sites and methylene sequence length in the branched nm-CopolyPE film enhanced abstraction of H, decomposition of hydroperoxide group ROOH, and generation of carbonyl compounds as compared with those in the linear nm-HomoPE film. This clearly establishes the role played by the backbone inhomogeneity. The effect of short chain branches and sequence length distributions on peak melting temperature T pm, and most probably lamellar thickness L o, was

  9. Nylon biodegradation by lignin-degrading fungi.

    OpenAIRE

    DEGUCHI, T; Kakezawa, M; Nishida, T.

    1997-01-01

    The biodegradation of nylon by lignin-degrading fungi was investigated. The fungus IZU-154 significantly degrade