The Photocatalytic Removal of Ortho Chlorophenol from Aqueous Solution Using Modified Fly Ash - Titanium Dioxide

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Mohamad Malakootian

2016-05-01

Full Text Available The photocatalytic process is a useful method for the effective removal of phenolic compounds. Conducted in the spring‒summer 2013 at the Engineering Research Center for Environmental Health, Kerman University of Medical Sciences, this experimental study used a modified fly ash‒TiO2 mixture to enhance the photocatalytic removal efficiency of ortho-chlorophenol. Fly ash obatined from the Thermal Power Plant in Zarand, Kerman, was initially washed with sulfuric acid before being oxidized with potassium permanganate. The mixture of modified fly ash and TiO2 was then used for the removal of ortho-chlorophenol in the presence of UV light and the factors involved in the removal process were optimized. It was found that the ortho-chlorophenol removal efficiency recorded by the mixture of modified fly ash and TiO2 was higher than that by each of the modified fly ash or TiO2/UV alone. It was, further, observed that removal efficiency with a modified fly ash to TiO2 ratio of 3:1 rose to 98.8% under optimum conditions (i.e., pH: 2; contact time: 2 h; room temperature (29±2˚C, and a catalyst dose of 0.6 g. The ortho-chlorophenol removal efficiency in real wastewater from the Coal Wash Plant in Zarand was recorded at 88.4%. Based on the results obtained from simultaneous use of modified fly ash and TiO2, the proposed method may be recommended for industrial applications.

Usefulness of a PARAFAC decomposition in the fiber selection procedure to determine chlorophenols by means SPME-GC-MS.

Science.gov (United States)

Morales, Rocío; Cruz Ortiz, M; Sarabia, Luis A

2012-05-01

In this work, a procedure based on solid-phase microextraction and gas chromatography coupled with mass spectrometry is proposed to determine chlorophenols in water without derivatization. The following chlorophenols are studied: 2,4-dichlorophenol; 2,4,6-trichlorophenol; 2,3,4,6-tetrachlorophenol and pentachlorophenol. Three kinds of SPME fibers, polyacrylate, polydimethylsiloxane, and polydimethylsiloxane/divinylbenzene are compared to identify the most suitable one for the extraction process on the basis of two criteria: (a) to select the equilibrium time studying the kinetics of the extraction, and (b) to obtain the best values of the figures of merit. In both cases, a three-way PARAllel FACtor analysis decomposition is used. For the first step, the three-way experimental data are arranged as follows: if I extraction times are considered, the tensor of data, X, of dimensions I × J × K is generated by concatenating the I matrices formed by the abundances of the J m/z ions recorded in K elution times around the retention time for each chlorophenol. The second-order property of PARAFAC (or PARAFAC2) assesses the unequivocal identification of each chlorophenol, as consequence, the loadings in the first mode estimated by the PARAFAC decomposition are the kinetic profile. For the second step, a calibration based on a PARAFAC decomposition is used for each fiber. The best figures of merit were obtained with PDMS/DVB fiber. The values of decision limit, CCα, achieved are between 0.29 and 0.67 μg L(-1) for the four chlorophenols. The accuracy (trueness and precision) of the procedure was assessed. This procedure has been applied to river water samples.

Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Okuyama, H., E-mail: hokuyama@kuchem.kyoto-u.ac.jp; Kitaguchi, Y.; Hattori, T.; Ueda, Y.; Ferrer, N. G.; Hatta, S.; Aruga, T. [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

2016-06-28

A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the “available” Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction.

Degradation of 4-chlorophenol by ozonation, γ radiation as well as ozonation combined with γ radiation

International Nuclear Information System (INIS)

Hu, J.; Wang, J.L.

2005-01-01

The radiolysis of aqueous 4-chlorophenol (4-CP) by gamma radiation in the presence of air and ozone was investigated. The 4-CP degradation, release of chloride ion, UV absorption spectrum, total organic carbon (TOC) and adsorbable organic halogens (AOX) was measured. Under the conditions of synergistic effect of ozone and radiation a complete degradation of 100 mg/L 4-CP was obtained at a dose of 6 kGy, without ozone the 4-chlorophenol was completely decomposed at 15 kGy. The total organic carbon (TOC) was reduced by 26% when ionizing radiation (at 15 kGy) combined with ozonation, and by 17% without ozone, respectively. Analysis of intermediate products resulting from synergistic effect of ozone and radiation of 4-CP was performed by using the GC/MS method. Some primary influencing factors such as irradiation time and initial 4-CP concentration were also discussed. The results showed that the degradation of 4-chlorophenol could described by first-order reaction kinetic model. There is potential for combination of irradiation with ozonation, which can remarkably reduce the irradiation dose increase the degradation efficiency of 4-CP.

Development and validation of a simple thin-layer chromatographic method for the analysis of p-chlorophenol in treated wastewater

Directory of Open Access Journals (Sweden)

Tešić Živoslav

2012-01-01

Full Text Available A thin-layer chromatographic method with densitometric detection was established for quantification of p-chlorophenol in waste water. Degradation efficiency of p-chlorophenol was monitored after each treatment of the wastewater samples. Degradation of p-chlorophenol was performed with advanced oxidation processes (AOPs, using UV, H2O2/UV, O3/H2O2/UV, O3 and O3/UV. Developed TLC procedure has been found to be simple, rapid and precise. The method was characterized by high sensitivity (limit of detection was 11 ng per band and limit of quantification 35 ng per band, linear range (from 75 to 500 ng per band, r = 0.9965, and high precision, accuracy (mean percentage recovery 98.6%, and specificity. Additionally, the efficiency of degradation was monitored using HPLC giving comparable results with RP TLC measurements. [Acknowledgement. This work was performed within the framework of the research project No. 172017 supported by the Ministry of Education and Science of Serbia.

Efficient photocatalytic reductive dechlorination of 4-chlorophenol to phenol on {0 0 1}/{1 0 1} facets co-exposed TiO_2 nanocrystals

International Nuclear Information System (INIS)

Jiang, Guodong; Wei, Meng; Yuan, Songdong; Chang, Qing

2016-01-01

Graphical abstract: - Highlights: • 4-Chlorophenol is dechlorinated over {0 0 1}/{1 0 1} co-exposed TiO_2 nanocrystals. • Photo-electrons are accumulated on {1 0 1} facets due to surface heterojunction. • Fluorine will trap photoelectrons to depress the dechlorination performance. • Sufficient isopropanol promotes the dechlorination activity and selectivity. - Abstract: 4-chlorophenol could be efficiently photoreductively dechlorinated over anatase TiO_2 nanocrystals with co-exposed {0 0 1} and {1 0 1} facets, which were synthesized and further characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Although fluorine could adsorb on {0 0 1} facets to decrease their surface energy, enabling TiO_2 to expose high energy {0 0 1} facets, the surface bonded fluorine might depress the photoreductive dechlorination efficiency of 4-chlorophenol, attributed to the electron trapping role of surface ≡Ti−F groups. Due to the formation of a surface heterojunction between {1 0 1} and {0 0 1} facets in a single TiO_2 nanocrystal, electrons and holes were spontaneously self-separated and selectively migrate to {1 0 1} and {0 0 1} facets, respectively. Electron trapping experiments demonstrated that photogenerated electrons are the responsible for the reductive dechlorinaton of 4-chlorophenol to phenol. To avoid the oxidative degradation of 4-chlorophenol by holes and ensure sufficient electrons to reductively dechlorinate the substrate, moderate scavengers were required in the reaction system and dissolved oxygen, which might deplete electron on TiO_2, also should be removed. With the optimal scavengers, the conversion efficiency of 4-chlorophenol (4-CP) achieved 97.5% and the selectivity for phenol was 92.5%, which were much higher than that of commercial TiO_2 P25.

Electro-oxidation of chlorophenols on poly(3,4-ethylenedioxythiophene)-poly(styrene sulphonate) composite electrode

International Nuclear Information System (INIS)

Pigani, L.; Musiani, M.; Pirvu, C.; Terzi, F.; Zanardi, C.; Seeber, R.

2007-01-01

The electrochemical behaviour of chlorinated phenols on Pt/poly(3,4-ethylenedioxy)thiophene,LiClO 4 and on Pt/poly(3,4-ethylenedioxy)thiophene,poly(sodium-4-styrenesulphonate) electrodes has been investigated in phosphate buffer solution. Poly(sodium-4-styrenesulphonate) exerts remarkable effect against the electrode fouling induced by oxidation of chlorophenols, allowing us to record the relevant anodic response even after repeated potential cycles. Hypotheses about the role exerted by poly(sodium 4-styrenesulphonate) are made, on the basis of evidences provided by several techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy, electrochemical microgravimetry and atomic force microscopy. Thanks to the fact that different chlorophenols show differences in the voltammetric responses, depending on number and position of the chloro substituents on the aromatic ring, applications of the modified electrode in the analysis of mixtures of chlorinated phenols are possible

Formation of industrial mixed culture biofilm in chlorophenol cultivated medium of microbial fuel cell

Science.gov (United States)

Hassan, Huzairy; Jin, Bo; Dai, Sheng; Ngau, Cornelius

2016-11-01

The formation of microbial biofilm while maintaining the electricity output is a challenging topic in microbial fuel cell (MFC) studies. This MFC critical factor becomes more significant when handling with industrial wastewater which normally contains refractory and toxic compounds. This study explores the formation of industrial mixed culture biofilm in chlorophenol cultivated medium through observing and characterizing microscopically its establishment on MFC anode surface. The mixed culture was found to develop its biofilm on the anode surface in the chlorophenol environment and established its maturity and dispersal stages with concurrent electricity generation and phenolic degradation. The mixed culture biofilm engaged the electron transfer roles in MFC by generating current density of 1.4 mA/m2 and removing 53 % of 2,4-dichlorophenol. The results support further research especially on hazardous wastewater treatment using a benign and sustainable method.

Evaluation of toxicity and genotoxicity of 2-chlorophenol on bacteria, fish and human cells.

Science.gov (United States)

Vlastos, Dimitris; Antonopoulou, Maria; Konstantinou, Ioannis

2016-05-01

Due to the extensive use of chlorophenols (CPs) in anthropogenic activities, 2-Chlorophenol (2-CP), among other CPs, can enter aquatic ecosystems and can be harmful to a variety of organisms, including bacteria, fish and humans, that are exposed directly and/or indirectly to such contaminated environments. Based on the existing knowledge and in order to move a step forward, the purpose of this study is to investigate the toxic and mainly the genotoxic effects of 2-CP using a combination of bioassays. The tests include the marine bacterium Vibrio fischeri and micronuclei induction in the erythrocytes of Carassius auratus as well as in cultured human lymphocytes. The results obtained reveal that 2-CP is able to induce dose-dependent toxic and genotoxic effects on the selected tested concentrations under the specific experimental conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of a novel hydrophobic/ion-exchange mixed-mode adsorbent for the dispersive solid-phase extraction of chlorophenols from environmental water samples.

Science.gov (United States)

Gao, Li; Wei, Yinmao

2016-08-01

A novel mixed-mode adsorbent was prepared by functionalizing silica with tris(2-aminoethyl)amine and 3-phenoxybenzaldehyde as the main mixed-mode scaffold due to the presence of the plentiful amino groups and benzene rings in their molecules. The adsorption mechanism was probed with acidic, natural and basic compounds, and the mixed hydrophobic and ion-exchange interactions were found to be responsible for the adsorption of analytes. The suitability of dispersive solid-phase extraction was demonstrated in the determination of chlorophenols in environmental water. Several parameters, including sample pH, desorption solvent, ionic strength, adsorbent dose, and extraction time were optimized. Under the optimal extraction conditions, the proposed dispersive solid-phase extraction coupled with high-performance liquid chromatography showed good linearity range and acceptable limits of detection (0.22∽0.54 ng/mL) for five chlorophenols. Notably, the higher extraction recoveries (88.7∽109.7%) for five chlorophenols were obtained with smaller adsorbent dose (10 mg) and shorter extraction time (15 min) compared with the reported methods. The proposed method might be potentially applied in the determination of trace chlorophenols in real water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetics of the degradation of 2-chlorophenol by ozonation at pH 3

International Nuclear Information System (INIS)

Sung Menghau; Huang, C.P.

2007-01-01

Prediction of byproduct distribution during ozonation is of importance to the design of treatment process. In this study, degradation products in direct ozonation of 2-chlorophenol in aqueous solution were identified by employing the chemical derivatization technique, specifically, silylation. Transient distribution of degradation products, in a semi-batch reactor under three ozone dosages were identified and determined by HPLC analysis. An empirical degradation pathway was proposed to describe the ozonation reaction. A mathematical protocol consisting of 11 equations and 12 rate constants was developed to solve and optimize the kinetic parameters. Modeling results revealed that the empirical pathway was capable of predicting the ozonation reaction at the beginning phase under a higher ozone dosage (e.g., greater than 6 mg/L g ). The degree of agreement between predicted and experimental data decreased as the ozone dosage decreased to 1.2 mg/L g . Results suggested that there was a dosage-dependent pathway in the direct ozonation of 2-chlorophenol

Gamma radiation treatment of pentachlorophenol, 2,4-dichlorophenol and 2-chlorophenol in water

International Nuclear Information System (INIS)

He Yongke; Liu Jun; Wu Jilan

2001-01-01

The aim of this work was to investigate γ radiation treatment of pentachlorophenol (PCP), 2,4- dichlorophenol (DCP) and o-chlorophenol (o-CP) in water. The dechlorination of PCP, DCP and o-CP has been studied using γ radiation as well as ozonization. G(CI-) is always much higher than the corresponding G(-PCP),this means that some primary radiolytic products are unstable during post irradiation. PCP is much easier to be decomposed under irradiation than that of simple chlorophenol. Some stable radiolytic intermediates were be detected. Primary analysis reveals some quinones among the final products with toxicity that remains unclear. In the pulse radiolytic experiment, it was determined that about 53% of radicals undergo electrotransfer and others undergo addition when OH radicals react with PCP. The values of COD(Mn) after irradiating PCP in dosage were determined. It is recommended to bubble ozone simultaneously when radiation (or electron beam) treat CPs contaminating water. (author)

Biological and photocatalytic treatment integrated with separation and reuse of titanium dioxide on the removal of chlorophenols in tap water

International Nuclear Information System (INIS)

Suryaman, Dhanus; Hasegawa, Kiyoshi

2010-01-01

We investigated biological, photocatalytic, and combination of biological and photocatalytic treatments in order to remove a mixture of 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, and pentachlorophenol in tap water (total: 100 mg L -1 , each: 25 mg L -1 ). The removal of chlorinated phenols was conducted with a flow biological treatment and a circulative flow photocatalytic treatment under black light and sunlight irradiations integrated with titanium dioxide separation and reuse. The combined biological-photocatalytic treatment significantly shortened the degradation and mineralization time of both the biological treatment and the photocatalytic treatment. The removed chlorophenols per hour by the combined biological-photocatalytic treatment was 25.8 mg h -1 , whereas by the combined photocatalytic-biological treatment was 10.5 mg h -1 . After a large portion of biodegradable 2-chlorophenol and 2,4-dichlorophenol, and around half amount of slightly biodegradable 2,4,5-trichlorophenol were removed by the biological treatment, the remained three chlorophenols, biorecalcitrant pentachlorophenol, and biodegradation products were completely removed by the subsequent photocatalytic treatment. Since titanium dioxide particles in tap water spontaneously sedimented on standing after the photocatalytic treatment, the combined treatment can be operated by integrating with the titanium dioxide separation and reuse. The TiO 2 particles were recovered and reused at least three times without significantly decreasing the removal efficiency.

Biological and photocatalytic treatment integrated with separation and reuse of titanium dioxide on the removal of chlorophenols in tap water

Energy Technology Data Exchange (ETDEWEB)

Suryaman, Dhanus, E-mail: dhanussuryaman@yahoo.com [Agency for the Assessment and Application of Technology, M.H. Thamrin No. 8, Jakarta 10340 (Indonesia); Department of Chemical and Biochemical Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Hasegawa, Kiyoshi [Department of Chemical and Biochemical Engineering, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

2010-11-15

We investigated biological, photocatalytic, and combination of biological and photocatalytic treatments in order to remove a mixture of 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, and pentachlorophenol in tap water (total: 100 mg L{sup -1}, each: 25 mg L{sup -1}). The removal of chlorinated phenols was conducted with a flow biological treatment and a circulative flow photocatalytic treatment under black light and sunlight irradiations integrated with titanium dioxide separation and reuse. The combined biological-photocatalytic treatment significantly shortened the degradation and mineralization time of both the biological treatment and the photocatalytic treatment. The removed chlorophenols per hour by the combined biological-photocatalytic treatment was 25.8 mg h{sup -1}, whereas by the combined photocatalytic-biological treatment was 10.5 mg h{sup -1}. After a large portion of biodegradable 2-chlorophenol and 2,4-dichlorophenol, and around half amount of slightly biodegradable 2,4,5-trichlorophenol were removed by the biological treatment, the remained three chlorophenols, biorecalcitrant pentachlorophenol, and biodegradation products were completely removed by the subsequent photocatalytic treatment. Since titanium dioxide particles in tap water spontaneously sedimented on standing after the photocatalytic treatment, the combined treatment can be operated by integrating with the titanium dioxide separation and reuse. The TiO{sub 2} particles were recovered and reused at least three times without significantly decreasing the removal efficiency.

Efficient photocatalytic reductive dechlorination of 4-chlorophenol to phenol on {0 0 1}/{1 0 1} facets co-exposed TiO{sub 2} nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Jiang, Guodong; Wei, Meng; Yuan, Songdong [College of Chemistry and chemical engineering, Hubei Collaborative Innovation Center for High Efficient Utilization of Solar Energy, Hubei University of Technology, Wuhan 430068 (China); Chang, Qing, E-mail: changqinghust@163.com [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074 (China)

2016-01-30

Graphical abstract: - Highlights: • 4-Chlorophenol is dechlorinated over {0 0 1}/{1 0 1} co-exposed TiO{sub 2} nanocrystals. • Photo-electrons are accumulated on {1 0 1} facets due to surface heterojunction. • Fluorine will trap photoelectrons to depress the dechlorination performance. • Sufficient isopropanol promotes the dechlorination activity and selectivity. - Abstract: 4-chlorophenol could be efficiently photoreductively dechlorinated over anatase TiO{sub 2} nanocrystals with co-exposed {0 0 1} and {1 0 1} facets, which were synthesized and further characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Although fluorine could adsorb on {0 0 1} facets to decrease their surface energy, enabling TiO{sub 2} to expose high energy {0 0 1} facets, the surface bonded fluorine might depress the photoreductive dechlorination efficiency of 4-chlorophenol, attributed to the electron trapping role of surface ≡Ti−F groups. Due to the formation of a surface heterojunction between {1 0 1} and {0 0 1} facets in a single TiO{sub 2} nanocrystal, electrons and holes were spontaneously self-separated and selectively migrate to {1 0 1} and {0 0 1} facets, respectively. Electron trapping experiments demonstrated that photogenerated electrons are the responsible for the reductive dechlorinaton of 4-chlorophenol to phenol. To avoid the oxidative degradation of 4-chlorophenol by holes and ensure sufficient electrons to reductively dechlorinate the substrate, moderate scavengers were required in the reaction system and dissolved oxygen, which might deplete electron on TiO{sub 2}, also should be removed. With the optimal scavengers, the conversion efficiency of 4-chlorophenol (4-CP) achieved 97.5% and the selectivity for phenol was 92.5%, which were much higher than that of commercial TiO{sub 2} P25.

Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry

International Nuclear Information System (INIS)

Ho, Tse-Tsung; Chen, Chung-Yu; Li Zuguang; Yang, Thomas Ching-Cherng; Lee, Maw-Rong

2012-01-01

Highlights: ► Ionic liquid (IL), ([C 4 MIM][PF 6 ]), was rapid synthesized by microwave radiation. ► Trace chlorophenols in landfill leachate were extract by SPME coated IL. ► The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive. - Abstract: A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C 4 MIM][PF 6 ]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography–mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography–mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 °C for 4 min. Linearity was observed from 0.1 to 1000 μg L −1 with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 μg L −1 . The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 μg L −1 . The results demonstrate that the IL-SPME-GC/MS method is highly effective in analyzing trace chlorophenols in landfill leachate.

Determination of chlorophenols in landfill leachate using headspace sampling with ionic liquid-coated solid-phase microextraction fibers combined with gas chromatography-mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Ho, Tse-Tsung; Chen, Chung-Yu [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); Li Zuguang [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China); College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, Zhejiang (China); Yang, Thomas Ching-Cherng [Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 82444, Taiwan (China); Lee, Maw-Rong, E-mail: mrlee@dragon.nchu.edu.tw [Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan (China)

2012-01-27

Highlights: Black-Right-Pointing-Pointer Ionic liquid (IL), ([C{sub 4}MIM][PF{sub 6}]), was rapid synthesized by microwave radiation. Black-Right-Pointing-Pointer Trace chlorophenols in landfill leachate were extract by SPME coated IL. Black-Right-Pointing-Pointer The IL-coated SPME-GC/MS method is low-cost, solvent-free and sensitive. - Abstract: A new microextraction technique based on ionic liquid solid-phase microextraction (IL-SPME) was developed for determination of trace chlorophenols (CPs) in landfill leachate. The synthesized ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C{sub 4}MIM][PF{sub 6}]), was coated onto the spent fiber of SPME for extraction of trace CPs. After extraction, the absorbed analytes were desorbed and quantified using gas chromatography-mass spectrometry (GC/MS). The term of the proposed method is as ionic liquid-coated of solid-phase microextraction combined with gas chromatography-mass spectrometry (IL-SPME-GC/MS). No carryover effect was found, and every laboratory-made ionic liquids-coated-fiber could be used for extraction at least eighty times without degradation of efficiency. The chlorophenols studied were 2,4-dichlorophenol (2,4-DP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP). The best results of chlorophenols analysis were obtained with landfill leachate at pH 2, headspace extraction for 4 min, and thermal desorption with the gas chromatograph injector at 240 Degree-Sign C for 4 min. Linearity was observed from 0.1 to 1000 {mu}g L{sup -1} with relative standard deviations (RSD) less than 7% and recoveries were over 87%. The limit of detection (LOD) for pentachlorophenol was 0.008 {mu}g L{sup -1}. The proposed method was tested by analyzing landfill leachate from a sewage farm. The concentrations of chlorophenols were detected to range from 1.1 to 1.4 {mu}g L{sup -1}. The results demonstrate that the IL-SPME-GC/MS method is highly effective in

Bioconcentration of atrazine and chlorophenols into roots and shoots of rice seedlings

International Nuclear Information System (INIS)

Su Yuhong; Zhu Yongguan

2006-01-01

Accumulation of o-chlorophenol (CP), 2,4-dichlorophenol (DCP), and atrazine (ATR), as single and mixed contaminants, from hydroponic solutions into roots and shoots of rice seedlings was studied following 48-h exposure of the plant roots. As single contaminants at low levels, the observed bioconcentration factors (BCFs) of CP and DCP with roots approximated the equilibrium values according to the partition-limited model. The BCF of atrazine with roots was about half the partition limit for unknown reasons. The BCFs of CP and ATR with shoots also approximated the partition limits, while the BCF for more lipophilic DCP with shoots was about half the estimated limit, due to insufficient water transport into plants for DCP. As mixed contaminants at low levels, the BCFs with both roots and shoots were comparable with those for the single contaminants; at high levels, the BCFs generally decreased because of the enhanced mixed-contaminant phytotoxicity, as manifested by the greatly reduced plant transpiration rate. - Uptakes of o-chlorophenol, 2,4-dichlorophenol, and atrazine at various levels from nutrient solution by roots and shoots of rice seedlings were investigated using a partition-limited model

Adsorption and bio-sorption of nickel ions and reuse for 2-chlorophenol catalytic ozonation oxidation degradation from water

International Nuclear Information System (INIS)

Ma, Wei; Zong, Panpan; Cheng, Zihong; Wang, Baodong; Sun, Qi

2014-01-01

Highlights: • Biomass and fly ash which were widespread for adsorption of heavy metal ions. • Preparation of catalyst by saturated adsorbents for 2-chlorophenol ozone degradation. • This work demonstrated that the O 3 /catalyst process was an effective pathway. • The use of nickel ions, fly ash and sawdust to achieve the recycling utilization of resources. -- Abstract: This work explored the preparation of an effective and low-cost catalyst and investigated its catalytic capacity for 2-chlorophenol ozonation oxidation degradation in wastewater by using an ozone oxidation batch reactor. The catalyst was directly prepared by the reuse of fly ash and sawdust after saturated adsorption of nickel ions from wastewater, which was proposed as an efficient and economic approach. The obtained catalyst was characterized by TGA, BET, FTIR, XRD, and SEM, the results showed that fly ash as the basic framework has high specific surface area and the addition of sawdust as the porogen agent could improve the pore structure of the catalyst. The adsorption of nickel ions by fly ash and sawdust from aqueous solution was also investigated in this study. The results obtained from the experiments indicated that adsorption of nickel ions by fly ash and biomass sawdust could be well described by Langmuir isotherm model and pseudo second order kinetic model. The catalytic performance of catalyst was studied in terms of the effect of time, liquid–solid ratio and pH on 2-chlorophenol ozonation degradation. It was found that the catalyst could effectively improve the ozonation reaction rate at pH = 7 with a 2:1 liquid–solid ratio. The kinetic study demonstrated that the reaction followed the first order model, and the rate constant increased 267% (0.03–0.1 min −1 ) of 2-chlorophenol ozonation degradation with 5 mmol/L concentration at pH = 7.0 compared with ozonation alone

Combined Effect of Temperature and Dissolved Oxygen on Degradation of 4-chlorophenol in Photo Microreactor

Czech Academy of Sciences Publication Activity Database

Vondráčková, Magdalena; Hejda, S.; Stavárek, Petr; Křišťál, Jiří; Klusoň, Petr

2015-01-01

Roč. 94, SI (2015), s. 35-38 ISSN 0255-2701 R&D Projects: GA ČR(CZ) GAP105/12/0664 Institutional support: RVO:67985858 Keywords : photo microreactor * phthalocyanine * chlorophenol oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.154, year: 2015

Elimination of 2-chlorophenol from aqueous solutions by marine algae: Evidences of the mechanism of adsorption

International Nuclear Information System (INIS)

Cuizano, N.A.; Llanos, B.P.

2009-01-01

The mechanism of the removal of 2-chlorophenol onto the marine algae Lessonia nigrescens Bory and Macrocystis integrifolia Bory from aqueous solutions was investigated in batch experiments. The effect of the presence of metallic ions in the adsorptive process was evaluated. The results show that lead slightly increases the adsorption of 2-chlorophenol. This suggests two different types of adsorption of both types of pollutants by the two marine algae and a possible synergic effect. Scanning electron microscopy and energy dispersive X-ray analyses predominantly indicated a surface adsorption. Finally, the change in Gibbs free energy (ΔG 0 ) of the process was determined. The results show that the adsorption is not spontaneous for none of the algae. This also corroborates the absence of electrostatic interactions and the existence of a polar interaction in an unfavorable environment surrounded by hydroxyl groups. (author)

Solar efficiency of a new deposited titania photocatalyst. Chlorophenol, pesticide and dye removal applications

Energy Technology Data Exchange (ETDEWEB)

Guillard, Chantal; Disdier, Jean; Maldonado, Manuel I.; Herrmann, Jean-Marie [Laboratoire D' Application de la Chimie a l' Environnement LACE (UMR 5634), Universite Claude Bernard Lyon I, Bat Jules Raulin, 69622 Villeurbanne Cedex (France); Monnet, Christine; Dussaud, Joseph [AHLSTROM Research and Services, ZI de l' Abbaye, 38780 Pont-Eveque (France); Malato, Sixto; Blanco, Julian [Plataforma Solar de Almeria-CIEMAT, Ctra. Senes Km. 4, 04200 Tabernas, Almeria (Spain)

2003-11-10

A specially designed titania photocatalyst was prepared by coating Ahlstrom non-woven paper, used as a flexible photocatalytic support, with Millennium PC500 anatase. At the same time, a new solar photoreactor (STEP) was designed based on the multi-step cascade falling-film principle to ensure good exposure to sunlight and good oxygenation of the effluent to be treated. Several types of reactants were treated: 4-chlorophenol as a model organic pollutant; formetanate, a widely used pesticide in horticulture; a mixture of pesticides used in vineyards; and indigo carmine (IC) and Congo red (CR), which are complex multifunctional dye molecules. Each reaction was performed simultaneously in a solar CPC slurry photoreactor and in the STEP photoreactor under identical solar exposure to better evaluate and validate the results obtained. The STEP solar reactor was found to be as efficient as the CPC for 4-chlorophenol and formetanate total degradation. In contrast, both dyes required longer treatment in STEP experiments. This new system, in which the final tedious filtration can actually be avoided, constitutes a good alternative to slurries.

Radiation-induced degradation of chlorophenols in aqueous solution

International Nuclear Information System (INIS)

Hu Jun; Wang Jianlong

2005-01-01

Radiation processing is a promising technology for applications in environmental protection, which includes wastewater treatment, micro-polluted drinking water treatment and the treatment of industrial wastewater containing various toxic and nonbiodegradable pollutants, municipal sewage and sludge disinfection, and flue gas desulfuration, etc. The paper reviews manly the recent progresses in radiolysis of chlorinated phenols in aqueous solution. Advantages and existing problems of the method in this particular application ar discussed. Mechanisms of radiation-induced degradation of chlorophenols, and the factors affecting the degradation efficiency, are discussed, too. It is concluded that combined approaches, such ozone oxidation and other methods, are of great help to the radiation processing application, in terms of lowering down the dose and increasing the efficient of pollutant removal. (authors)

Thermodynamic Study of Adsorption of Phenol, 4-Chlorophenol, and 4-Nitrophenol on Activated Carbon Obtained from Eucalyptus Seed

Directory of Open Access Journals (Sweden)

Nelson Giovanny Rincón-Silva

2015-01-01

Full Text Available Activated carbons from shell eucalyptus (Eucalyptus globulus were prepared by chemical activation through impregnation with solutions of two activators: sulfuric acid and sodium hydroxide, the surface areas for activated carbons with base were 780 and 670 m2 g−1 and the solids activated with acid were 150 and 80 m2 g−1. These were applying in adsorption of priority pollutants: phenol, 4-nitrophenol, and 4-chlorophenol from aqueous solution. Activated carbon with the highest adsorption capacity has values of 2.12, 2.57, and 3.89 on phenol, 4-nitrophenol, and 4-chlorophenol, respectively, and was activated with base. In general, all carbons adsorption capacity was given in the following order: 4-chlorophenol > 4-nitrophenol > phenol. Adsorption isotherms of phenols on activated carbons were fitted to the Langmuir, Freundlich, and Dubinin-Radusckevisch-Kanager models, finding great association between them and experimental data. A thermodynamic study was performed, the exothermic nature and spontaneous nature of the adsorption process were confirmed, and the favorability of adsorption on activated carbons with NaOH was confirmed by energy relations and concluded that the adsorption process of phenolic compounds from the activated carbon obtained is physical. The pH of solutions and pH at point of zero charge of the solid play an important role in the adsorption process.

Adsorption and bio-sorption of nickel ions and reuse for 2-chlorophenol catalytic ozonation oxidation degradation from water

Energy Technology Data Exchange (ETDEWEB)

Ma, Wei, E-mail: chmawv@yahoo.com [School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Zong, Panpan; Cheng, Zihong [School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Baodong; Sun, Qi [National Institute of Clean-and-low Carbon Energy, Beijing 102209 (China)

2014-02-15

Highlights: • Biomass and fly ash which were widespread for adsorption of heavy metal ions. • Preparation of catalyst by saturated adsorbents for 2-chlorophenol ozone degradation. • This work demonstrated that the O{sub 3}/catalyst process was an effective pathway. • The use of nickel ions, fly ash and sawdust to achieve the recycling utilization of resources. -- Abstract: This work explored the preparation of an effective and low-cost catalyst and investigated its catalytic capacity for 2-chlorophenol ozonation oxidation degradation in wastewater by using an ozone oxidation batch reactor. The catalyst was directly prepared by the reuse of fly ash and sawdust after saturated adsorption of nickel ions from wastewater, which was proposed as an efficient and economic approach. The obtained catalyst was characterized by TGA, BET, FTIR, XRD, and SEM, the results showed that fly ash as the basic framework has high specific surface area and the addition of sawdust as the porogen agent could improve the pore structure of the catalyst. The adsorption of nickel ions by fly ash and sawdust from aqueous solution was also investigated in this study. The results obtained from the experiments indicated that adsorption of nickel ions by fly ash and biomass sawdust could be well described by Langmuir isotherm model and pseudo second order kinetic model. The catalytic performance of catalyst was studied in terms of the effect of time, liquid–solid ratio and pH on 2-chlorophenol ozonation degradation. It was found that the catalyst could effectively improve the ozonation reaction rate at pH = 7 with a 2:1 liquid–solid ratio. The kinetic study demonstrated that the reaction followed the first order model, and the rate constant increased 267% (0.03–0.1 min{sup −1}) of 2-chlorophenol ozonation degradation with 5 mmol/L concentration at pH = 7.0 compared with ozonation alone.

CHLOROBENZENES, CHLOROPHENOLS, PHAS AND LOW CHLORINATED DIOXIN/FURAN POST-BOILER TOXICITY INDICATORS IN MUNICIPAL SOLID WASTE INCINERATORS

Science.gov (United States)

Research has sought indicator compounds for fast and less costly predictive monitoring of polychlorinated dibenzo-p-dioxin and furans, PCDD/F, toxic equivalent concentrations or TEQs. Studies have shown chlorobenzenes and chlorophenols had a good correlation with TEQ, suggesting ...

Experimental and DFT study of the degradation of 4-chlorophenol on hierarchical micro-/nanostructured oxide films

Czech Academy of Sciences Publication Activity Database

Guerin, V. M.; Žouželka, Radek; Bíbová-Lipšová, Hana; Jirkovský, Jaromír; Rathouský, Jiří; Pauporté, T.

2015-01-01

Roč. 168, JUN 01 (2015), s. 132-140 ISSN 0926-3373 R&D Projects: GA MK(CZ) DF11P01OVV012 Keywords : 4-Chlorophenol degradation * DFT modeling * ZnO hierarchical nanostructures Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.328, year: 2015

Application of Azolla for 2-Chlorophenol and 4-Chrorophenol Removal from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Mohammad Ali Zazouli

2013-09-01

Full Text Available Background and purpose: The 2-chlorophenol (2-CP and 4-chlorophenol (4-CP are phenolic compounds which may have adverse effects on human and environment. Therefore, removing these compounds from water and wastewater is necessary. This study aims to analyze 2-CP and 4-CP removal by using Azolla filiculoides biomass. Materials & Methods: Azolla biomass was sun dried, crushed and sieved to particle sizes ranging 1-2 mm. Then it was treated with 0.1M HCl for 5h followed by washing with distilled water and it was used as adsorbent. The residues concentration of 2-CP and 4-CP was measured by spectrophotometer in λmax of 274 and 280 nm, respectively. Results: The solute removed increases as contact time rises. The equilibrium time for 2-CP and 4-CP is 90 and 75, respectively. The removal efficiency of 4-CP is more than 2-CP. An increase in initial concentration of both compounds can lead to decrease of their removal efficiency. The optimum pH to remove both compounds is 5. The equilibrium data matched best on Freundlich isotherm and the adsorption kinetic model follows pseudo-second model. Conclusion: The results indicated that Azolla is an effective adsorbent for removing 2-CP and 4-CP from water and wastewater.

Rapid and effective decontamination of chlorophenol-contaminated soil by sorption into commercial polymers: concept demonstration and process modeling.

Science.gov (United States)

Tomei, M Concetta; Mosca Angelucci, Domenica; Ademollo, Nicoletta; Daugulis, Andrew J

2015-03-01

Solid phase extraction performed with commercial polymer beads to treat soil contaminated by chlorophenols (4-chlorophenol, 2,4-dichlorophenol and pentachlorophenol) as single compounds and in a mixture has been investigated in this study. Soil-water-polymer partition tests were conducted to determine the relative affinities of single compounds in soil-water and polymer-water pairs. Subsequent soil extraction tests were performed with Hytrel 8206, the polymer showing the highest affinity for the tested chlorophenols. Factors that were examined were polymer type, moisture content, and contamination level. Increased moisture content (up to 100%) improved the extraction efficiency for all three compounds. Extraction tests at this upper level of moisture content showed removal efficiencies ≥70% for all the compounds and their ternary mixture, for 24 h of contact time, which is in contrast to the weeks and months, normally required for conventional ex situ remediation processes. A dynamic model characterizing the rate and extent of decontamination was also formulated, calibrated and validated with the experimental data. The proposed model, based on the simplified approach of "lumped parameters" for the mass transfer coefficients, provided very good predictions of the experimental data for the absorptive removal of contaminants from soil at different individual solute levels. Parameters evaluated from calibration by fitting of single compound data, have been successfully applied to predict mixture data, with differences between experimental and predicted data in all cases being ≤3%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Formulation and stabilization of an Arthrobacter strain with good storage stability and 4-chlorophenol-degradation activity for bioremediation

NARCIS (Netherlands)

Bjerketorp, Joakim; Röling, Wilfred F.M.; Feng, Xin Mei; Garcia, Armando Hernández; Heipieper, Hermann J.; Håkansson, Sebastian

Chlorophenols are widespread and of environmental concern due to their toxic and carcinogenic properties. Development of less costly and less technically challenging remediation methods are needed; therefore, we developed a formulation based on micronized vermiculite that, when air-dried, resulted

Chlorophenols Sorption on Multi-Walled Carbon Nanotubes: DFT Modeling and Structure-Property Relationship Analysis

OpenAIRE

Watkins, Marquita; Sizochenko, Natalia; Moore, Quentarius; Golebiowski, Marek; Leszczynska, Danuta; Leszczynski, Jerzy

2017-01-01

Presence of chlorophenols in drinking water could be hazardous to human health. Optimization and computational modeling of experimental conditions of adsorption lead to understanding the mechanisms of this process and to creating the efficient experimental equipment. In the current study, we investigated multi-walled carbon nanotubes by means of density functional theory (DFT) approach. This is applied to study selected types of interactions between six solvents, five types of nanotubes, and ...

A sensitive electrochemical chlorophenols sensor based on nanocomposite of ZnSe quantum dots and cetyltrimethylammonium bromide

International Nuclear Information System (INIS)

Li, Jianjun; Li, Xiao; Yang, Ran; Qu, Lingbo; Harrington, Peter de B.

2013-01-01

Graphical abstract: A very sensitive and simple electrochemical sensor for chlorophenols (CPs) based on nanocomposite of cetyltrimethylammonium bromide (CTAB) and ZnSe quantum dots (ZnSe–CTAB) through electrostatic self-assembly technology was built for the first time. The nanocomposite of ZnSe–CTAB introduced a favorable access for the electron transfer and showed excellent electrocatalytic activity for the oxidation of CPs. -- Highlights: •Nanocomposite based ZnSe QDs and CTAB was prepared and characterized. •A novel electrochemical sensor for the determination of CPs was built. •The proposed sensor was more sensitive, simple and environment-friendly. -- Abstract: In this work, a very sensitive and simple electrochemical sensor for chlorophenols (CPs) based on a nanocomposite of cetyltrimethylammonium bromide (CTAB) and ZnSe quantum dots (ZnSe–CTAB) through electrostatic self-assembly technology was built for the first time. The composite of ZnSe–CTAB introduced a favorable access for the electron transfer and gave superior electrocatalytic activity for the oxidation of CPs than ZnSe QDs and CTAB alone. Differential pulse voltammetry (DPV) was used for the quantitative determination of the CPs including 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP). Under the optimum conditions, the peak currents of the CPs were proportional to their concentrations in the range from 0.02 to 10.0 μM for 2-CP, 0.006 to 9.0 μM for 2,4-DCP, and 0.06 to 8.0 for PCP. The detection limits were 0.008 μM for 2-CP, 0.002 μM for 2,4-DCP, and 0.01 μM for PCP, respectively. The method was successfully applied for the determination of CPs in waste water with satisfactory recoveries. This ZnSe–CTAB electrode system provides operational access to design environment-friendly CPs sensors

The toxic effects of chlorophenols and associated mechanisms in fish

International Nuclear Information System (INIS)

Ge, Tingting; Han, Jiangyuan; Qi, Yongmei; Gu, Xueyan; Ma, Lin; Zhang, Chen; Naeem, Sajid; Huang, Dejun

2017-01-01

Highlights: • We review the toxic effects of chlorophenols (CPs) and underlying mechanisms in fish. • CPs induce lethal effects, oxidative stress, endocrine disruption, reproductive toxicity and apoptosis in fish. • CPs exhibit toxicity through multiple signaling pathways in fish and different pathways co-exist under the same conditions. • Studies on DNA methylation provide new insights into our understanding of epigenetic mechanisms of CPs-induced toxicity. • Mechanisms studies on CPs toxicity performed under environmental concentrations need more attentions. - Abstract: Chlorophenols (CPs) are ubiquitous contaminants in the environment primarily released from agricultural and industrial wastewater. These compounds are not readily degraded naturally, and easily accumulate in organs, tissues and cells via food chains, further leading to acute and chronic toxic effects on aquatic organisms. Herein, we review the available literature regarding CP toxicity in fish, with special emphasis on the potential toxic mechanisms. CPs cause oxidative stress via generation of reactive oxygen species, induction of lipid peroxidation and/or oxidative DNA damage along with inhibition of antioxidant systems. CPs affect immune system by altering the number of mature B cells and macrophages, while suppressing phagocytosis and down-regulating the expression of immune factors. CPs also disrupt endocrine function by affecting hormone levels, or inducing abnormal gene expression and interference with hormone receptors. CPs at relatively higher concentrations induce apoptosis via mitochondria-mediated pathway, cell death receptor-mediated pathway, and/or DNA damage-mediated pathway. CPs at relatively lower concentrations promote cell proliferation, and foster cancers-prone environment by increasing the rate of point mutations and oxidative DNA lesions. These toxic effects in fish are induced directly by CPs per se or indirectly by their metabolic products. In addition, recent

The toxic effects of chlorophenols and associated mechanisms in fish

Energy Technology Data Exchange (ETDEWEB)

Ge, Tingting; Han, Jiangyuan; Qi, Yongmei; Gu, Xueyan; Ma, Lin; Zhang, Chen; Naeem, Sajid; Huang, Dejun, E-mail: huangdj@lzu.edu.cn

2017-03-15

Highlights: • We review the toxic effects of chlorophenols (CPs) and underlying mechanisms in fish. • CPs induce lethal effects, oxidative stress, endocrine disruption, reproductive toxicity and apoptosis in fish. • CPs exhibit toxicity through multiple signaling pathways in fish and different pathways co-exist under the same conditions. • Studies on DNA methylation provide new insights into our understanding of epigenetic mechanisms of CPs-induced toxicity. • Mechanisms studies on CPs toxicity performed under environmental concentrations need more attentions. - Abstract: Chlorophenols (CPs) are ubiquitous contaminants in the environment primarily released from agricultural and industrial wastewater. These compounds are not readily degraded naturally, and easily accumulate in organs, tissues and cells via food chains, further leading to acute and chronic toxic effects on aquatic organisms. Herein, we review the available literature regarding CP toxicity in fish, with special emphasis on the potential toxic mechanisms. CPs cause oxidative stress via generation of reactive oxygen species, induction of lipid peroxidation and/or oxidative DNA damage along with inhibition of antioxidant systems. CPs affect immune system by altering the number of mature B cells and macrophages, while suppressing phagocytosis and down-regulating the expression of immune factors. CPs also disrupt endocrine function by affecting hormone levels, or inducing abnormal gene expression and interference with hormone receptors. CPs at relatively higher concentrations induce apoptosis via mitochondria-mediated pathway, cell death receptor-mediated pathway, and/or DNA damage-mediated pathway. CPs at relatively lower concentrations promote cell proliferation, and foster cancers-prone environment by increasing the rate of point mutations and oxidative DNA lesions. These toxic effects in fish are induced directly by CPs per se or indirectly by their metabolic products. In addition, recent

The Pd-catalyzed hydrodechlorination of chlorophenols in aqueous solutions under mild conditions: A promising approach to practical use in wastewater

International Nuclear Information System (INIS)

Xia Chuanhai; Liu Ying; Zhou Shiwei; Yang Cuiyun; Liu Sujing; Xu Jie; Yu Junbao; Chen Jiping; Liang Xinmiao

2009-01-01

Catalytic hydrotreating of chlorophenols was carried out in water with Pd/C at 25 deg. C under atmospheric pressure. 1.0% (w/w) monocholophenols was completely dechlorinated within 60 min. Phenol, cyclohexanone and cyclohexanol were formed. In contrast to the dechlorination of monochlorophenols, the hydrogenation reaction of polychlorinated phenols became difficult and reaction rates were strongly dependent upon the number of the chlorine atoms. The solvent property had a considerably important influence on the dechlorination reaction. Water as a solvent showed more advantages than organic solvents. It was much easier to be hydrodechlorinated for chlorophenols in aqueous solutions. However, the presence of THF, dioxane, DMSO or DMF in water was disadvantageous to the reaction and easily to cause Pd/C deactivation. Additionally, when different halogenated organic compounds were present in aqueous solution, the dehalogenation reaction was the competitive hydrogenation process.

The Pd-catalyzed hydrodechlorination of chlorophenols in aqueous solutions under mild conditions: A promising approach to practical use in wastewater

Energy Technology Data Exchange (ETDEWEB)

Xia Chuanhai, E-mail: chuanhaixia@gmail.com [Yantai Institute of Coastal Zone Research for Sustainable Development, CAS, Yantai 264003 (China); Liu Ying; Zhou Shiwei; Yang Cuiyun; Liu Sujing [Yantai Institute of Coastal Zone Research for Sustainable Development, CAS, Yantai 264003 (China); Xu Jie [Dalian Institute of Chemical Physics, CAS, Dalian, 116021 (China); Yu Junbao [Yantai Institute of Coastal Zone Research for Sustainable Development, CAS, Yantai 264003 (China); Chen Jiping; Liang Xinmiao [Dalian Institute of Chemical Physics, CAS, Dalian, 116021 (China)

2009-09-30

Catalytic hydrotreating of chlorophenols was carried out in water with Pd/C at 25 deg. C under atmospheric pressure. 1.0% (w/w) monocholophenols was completely dechlorinated within 60 min. Phenol, cyclohexanone and cyclohexanol were formed. In contrast to the dechlorination of monochlorophenols, the hydrogenation reaction of polychlorinated phenols became difficult and reaction rates were strongly dependent upon the number of the chlorine atoms. The solvent property had a considerably important influence on the dechlorination reaction. Water as a solvent showed more advantages than organic solvents. It was much easier to be hydrodechlorinated for chlorophenols in aqueous solutions. However, the presence of THF, dioxane, DMSO or DMF in water was disadvantageous to the reaction and easily to cause Pd/C deactivation. Additionally, when different halogenated organic compounds were present in aqueous solution, the dehalogenation reaction was the competitive hydrogenation process.

CHLOROPHENOL DEGRADATION BY ELECTROCATALYSIS COMBINED WITH UV RADIATION%电催化与紫外光辐射降解氯酚

Institute of Scientific and Technical Information of China (English)

吴祖成; 叶倩; 周明华; 丛燕青

2002-01-01

@@ Chlorinated organic compounds, especially chlorophenols are well-known water priority pollutant family due to their toxicity and potential health hazard. As biological treatment processes for the degradation of chlorinated phenols have not been effective, various technologies and processes such as activated carbon adsorption[1], chemical oxidation[2], have been conventionally attempted for phenolic waster treatment. Recently, advanced oxidation processes (AOPs) have attracted a great deal of attention for treatment of phenolic wastewater, among these chemical oxidation ultraviolet (UV) oxidation system[3], anodic oxidation and indirect electro-oxidation have been widely studied[4]. Though a number of researchers worked on the degradation of chlorophenol by UV radiation or electrochemical processes, there are few reports on both methods for organic wastewater treatment. If these two processes can operate in harmony, the degradation efficiency would be enhanced.

Performance and Mechanism of Piezo-Catalytic Degradation of 4-Chlorophenol: Finding of Effective Piezo-Dechlorination.

Science.gov (United States)

Lan, Shenyu; Feng, Jinxi; Xiong, Ya; Tian, Shuanghong; Liu, Shengwei; Kong, Lingjun

2017-06-06

Piezo-catalysis was first used to degrade a nondye pollutant, 4-chlorophenol (4-CP). In this process, hydrothermally synthesized tetragonal BaTiO 3 nano/micrometer-sized particles were used as the piezo-catalyst, and the ultrasonic irradiation with low frequency was selected as the vibration energy to cause the deformation of tetragonal BaTiO 3 . It was found that the piezoelectric potential from the deformation could not only successfully degrade 4-chlorophenol but also effectively dechlorinate it at the same time, and five kinds of dechlorinated intermediates, hydroquinone, benzoquinone, phenol, cyclohexanone, and cyclohexanol, were determined. This is the first sample of piezo-dechlorination. Although various active species, including h + , e - , •H, •OH, •O 2 - , 1 O 2 , and H 2 O 2 , were generated in the piezoelectric process, it was confirmed by ESR, scavenger studies, and LC-MS that the degradation and dechlorination were mainly attributed to •OH radicals. These •OH radicals were chiefly derived from the electron reduction of O 2 , partly from the hole oxidation of H 2 O. These results indicated that the piezo-catalysis was an emerging and effective advanced oxidation technology for degradation and dechlorination of organic pollutants.

Microrespirometric determination of the effectiveness factor and biodegradation kinetics of aerobic granules degrading 4-chlorophenol as the sole carbon source

Energy Technology Data Exchange (ETDEWEB)

Vital-Jacome, Miguel [Department of Biotechnology and Bioengineering, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav-IPN), Av. IPN 2508, 07360 México DF, México (Mexico); Buitrón, Germán; Moreno-Andrade, Ivan; Garcia-Rea, Victor [Laboratory for Research on Advanced Process for Water Treatment, Unidad Académica Juriquilla, Instituto de Ingeniería, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, Querétaro 76320, México (Mexico); Thalasso, Frederic, E-mail: thalasso@cinvestav.mx [Department of Biotechnology and Bioengineering, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav-IPN), Av. IPN 2508, 07360 México DF, México (Mexico)

2016-08-05

Highlights: • Microrespirometry was used to characterize aerobic granules. • Kinetic parameters for 4-chorophenol degradation were determined. • Intrinsic and apparent kinetic parameters were quantified and contrasted. • Aerobic granules presented lower μ{sub max} and higher K{sub S} than disaggregated granules. • Microrespirometry can be useful in model development and calibration. - Abstract: In this study, a microrespirometric method was used, i.e., pulse respirometry in microreactors, to characterize mass transfer and biodegradation kinetics in aerobic granules. The experimental model was an aerobic granular sludge in a sequencing batch reactor (SBR) degrading synthetic wastewater containing 4-chlorophenol as the sole carbon source. After 15 days of acclimation, the SBR process degraded 4-chlorophenol at a removal rate of up to 0.9 kg COD m{sup −3} d{sup −1}, and the degradation kinetics were well described by the Haldane model. The microrespirometric method consisted of injecting pulses of 4-chlorophenol into the 24 wells of a microreactor system containing the SBR samples. From the respirograms obtained, the following five kinetic parameters were successfully determined during reactor operation: (i) Maximum specific oxygen uptake rate, (ii) substrate affinity constant, (iii) substrate inhibition constant, (iv) maximum specific growth rate, and (v) cell growth yield. Microrespirometry tests using granules and disaggregated granules allowed for the determination of apparent and intrinsic parameters, which in turn enabled the determination of the effectiveness factor of the granular sludge. It was concluded that this new high-throughput method has the potential to elucidate the complex biological and physicochemical processes of aerobic granular biosystems.

Microrespirometric determination of the effectiveness factor and biodegradation kinetics of aerobic granules degrading 4-chlorophenol as the sole carbon source

International Nuclear Information System (INIS)

Vital-Jacome, Miguel; Buitrón, Germán; Moreno-Andrade, Ivan; Garcia-Rea, Victor; Thalasso, Frederic

2016-01-01

Highlights: • Microrespirometry was used to characterize aerobic granules. • Kinetic parameters for 4-chorophenol degradation were determined. • Intrinsic and apparent kinetic parameters were quantified and contrasted. • Aerobic granules presented lower μ_m_a_x and higher K_S than disaggregated granules. • Microrespirometry can be useful in model development and calibration. - Abstract: In this study, a microrespirometric method was used, i.e., pulse respirometry in microreactors, to characterize mass transfer and biodegradation kinetics in aerobic granules. The experimental model was an aerobic granular sludge in a sequencing batch reactor (SBR) degrading synthetic wastewater containing 4-chlorophenol as the sole carbon source. After 15 days of acclimation, the SBR process degraded 4-chlorophenol at a removal rate of up to 0.9 kg COD m"−"3 d"−"1, and the degradation kinetics were well described by the Haldane model. The microrespirometric method consisted of injecting pulses of 4-chlorophenol into the 24 wells of a microreactor system containing the SBR samples. From the respirograms obtained, the following five kinetic parameters were successfully determined during reactor operation: (i) Maximum specific oxygen uptake rate, (ii) substrate affinity constant, (iii) substrate inhibition constant, (iv) maximum specific growth rate, and (v) cell growth yield. Microrespirometry tests using granules and disaggregated granules allowed for the determination of apparent and intrinsic parameters, which in turn enabled the determination of the effectiveness factor of the granular sludge. It was concluded that this new high-throughput method has the potential to elucidate the complex biological and physicochemical processes of aerobic granular biosystems.

Experimental Evaluation Use of Semifluidized Bed Adsorber for the Treatment of P-chlorophenol and O-cresol in Wastewater using Activated Carbon as Adsorbent

Directory of Open Access Journals (Sweden)

Saad Hanash Ammar

2015-12-01

Full Text Available In the present work the performance of semifluidized bed adsorber was evaluated for removal of phenolic compound from wastewater using commercial activated carbon as adsorbent. P-chlorophenol (4-Chlorophenol and o-cresol (2-methylphenol was selected as a phenolic compound for that purpose. The phenols percent removal, in term of breakthrough curves were studied as affected by hydrodynamics limitations which include minimum and maximum semifluidization velocities and packed bed formation in the column by varying various parameters such as inlet liquid superficial velocity (from Uminsf to 8Uminsf m/s, and retaining grid (sometimes referred to as adsorbent loading to initial static bed height ratio (from 3-4.5. Inlet phenols concentration (50-400 mg/l and initial pH of the liquid solutions feed (from 4 to 10 were also studied. The experimental semifluidized adsorber unit was designed and constructed in Chem. Eng. labs at Al-Nahrain University (consisted of a QVF glass tube 2.54 cm inside diameter, and 70cm length. The results showed that the initial percent removal of phenolic compounds (P-chlorophenol and o-cresol decrease with increasing the superficial liquid velocity while the time required reaching equilibrium state decreased. Also it slightly affected with the increase in the retaining grid height and the time required to reach the equilibrium value decreased.

Preparation and characterizations of CuO doped ZnO nano-structure for the photocatalytic degradation of 4-chlorophenol under visible light

Directory of Open Access Journals (Sweden)

Afsaneh Shokri

2016-12-01

Full Text Available In the present investigation, a ZnO nanostructure was synthesized by means of precipitation and sonochemical methods. The X-ray diffraction (XRD pattern indicated that the wurtzite structure of ZnO had a hexagonal symmetry and there was no impurity. The average ZnO particles crystallite size was calculated at about 41 nm. The SEM and TEM images revealed nanostructure ZnO particles with a cauliflower-like and rod morphology with dimensions of 85, 79 and 117 nm. In order to investigate the increment of ZnO photoactivity under visible light, the CuO doped ZnO nanostructures were fabricated by a wet impregnation method using copper oxide as the copper source and ZnO as the precursor. The XRD analysis confirmed that the CuO phase was present in the as-prepared sample and the average size of nano crystalline decreased to about 36 nm. The DRS spectra indicated the extended absorption of CuO-ZnO to the visible range as a result of band gap reduction to 2.9 eV (in comparison of 3.2 eV in ZnO. In order to investigate the photocatalytic activity of the synthesized photocatalyst, the degradation of 4-Chlorophenol under visible light was performed. Sixteen experiments using full factorial were executed by adjusting four parameters (amount of catalyst, initial concentration of 4-Chlorophenol, pH, and time of irradiation. An empirical expression was proposed and successfully used to model the photocatalytic process with a high correlation, and an optimal experimental region was also obtained. According to the developed model for degradation and the subsequent ANOVA test using Design Expert software, the time of irradiation with a 46.57% effect played the most important role in the photocatalytic activity, while the influences of parameters on each other were negligible. Optimal experimental conditions for 4-Chlorophenol concentration (0.01 g/L were found at an initial pH =8 and a catalyst loading of 0.07 g/L. The results indicated that CuO-ZnO can remove 95

Room-temperature Pd-catalyzed C-H chlorination by weak coordination: one-pot synthesis of 2-chlorophenols with excellent regioselectivity.

Science.gov (United States)

Sun, Xiuyun; Sun, Yonghui; Zhang, Chao; Rao, Yu

2014-02-07

A room-temperature Pd(II)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.

Modeling of adsorption isotherms of phenol and chlorophenols onto granular activated carbon. Part I. Two-parameter models and equations allowing determination of thermodynamic parameters.

Science.gov (United States)

Hamdaoui, Oualid; Naffrechoux, Emmanuel

2007-08-17

The adsorption equilibrium isotherms of five phenolic compounds from aqueous solutions onto granular activated carbon (GAC) were studied and modeled. Phenol (Ph), 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP) were chosen for the adsorption tests. To predict the adsorption isotherms and to determine the characteristic parameters for process design, seven isotherm models: Langmuir (five linear forms), Freundlich, Elovich, Temkin, Fowler-Guggenheim, Kiselev, and Hill-de Boer models were applied to experimental data. The results reveal that the adsorption isotherm models fitted the data in the order: Fowler-Guggenheim>Hill-de Boer>Temkin>Freundlich>Kiselev>Langmuir isotherms. Adsorption isotherms modeling shows that the interaction of phenolic compounds with activated carbon surface is localized monolayer adsorption, that is adsorbed molecules are adsorbed at definite, localized sites. Each site can accommodate only one molecule. The interaction among adsorbed molecules is repulsive and there is no association between them, adsorption is carried out on energetically different sites and is an exothermic process. Uptake of phenols increases in the order Ph<2-CP<4-CPchlorophenols, it seems that the magnitude of adsorption is directly proportional to their degree of chlorination.

Structural and antimicrobial studies of coordination compounds of VO(II, Co(II, Ni(II and Cu(II with some Schiff bases involving 2-amino-4-chlorophenol

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A. P. MISHRA

2009-05-01

Full Text Available Complexes of tailor-made ligands with life essential metal ions may be an emerging area to answer the problem of multi-drug resistance (MDR. The coordination complexes of VO(II, Co(II, Ni(II and Cu(II with the Schiff bases derived from 2-hydroxyacetophenone/2-chlorobenzaldehyde with 2-ami¬no-4-chlorophenol were synthesized and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, ESR, FAB mass, thermal and magnetic susceptibility measurements. The FAB mass and thermal data show degradation of the complexes. The ligand A (2-hydroxyacetophenone-2amino-4-chlorophenol behaved as tridentate and ligand B (2-chlorobenzylidene-2-amino-4-chlorophenol as bidentate, coordinating through O and N donors. The complexes [VO(A(H2O]×xH2O, [M(A(H2On]×xH2O for Co and Ni, [Cu(A(H2O] and [VO(B2]×xH2O, [M(B2(H2On] for Co and Cu and [Ni(B2] exhibited coordination numbers 4, 5 or 6. X-ray powder diffraction data (a = 11.00417 Å, b = 11.706081 Å and c = 54.46780 Å showed that [Cu(CACP2(H2O2], complex 8, crystallized in the orthorhombic system. The in vitro biological screening effects of the investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus and Streptococcus fecalis and the fungi Aspergillus niger, Trichoderma polysporum and Candida albicans by the serial dilution method. A comparative study of the MIC values of the Schiff base and their [M(B2(H2O2] complexes (Co(II, complex 6 and Cu(II, complex 8, indicated that the metal complexes exhibited a higher or lower antimicrobial activity than 2-chlorobenzylidene-2-amino-4-chlorophenol as the free ligand (B.

Degradation of 4-Chlorophenol Under Sunlight Using ZnO Nanoparticles as Catalysts

Science.gov (United States)

Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Sherazi, Tufail H.; Kumar, Raj

2018-03-01

Herein we demonstrate a simplistic microwave assisted chemical precipitation approach regarding the synthesis of zinc oxide nanoparticles. As-prepared ZnO nanoparticles (NPs) were characterized by UV-visible spectroscopy, Fourier transform infra-red spectroscopy, atomic force microscopy and x-ray diffractometry and scrutinized as photo-catalysts for degradation of 4-chlorophenol (4-CP) under sunlight. The study substantiated that 98.5% of 4-CP was degraded within 20 min in the absence of initiator like H2O2 which reflects an outstanding prospective use for ZnO NPs as photo-catalysts. The nanocatalysts were recycled four times and still showed catalytic efficiency up to 95.5% for degradation of 4-CP in the specified 20 min.

Rotating biological contractor treatment of 2-nitrophenol and 2-chlorophenol containing hazardous wastes

International Nuclear Information System (INIS)

Tokuz, R.Y.

1990-01-01

Rotating Biological Contactors (RBCs) have a number of advantages over other biological treatment systems. For example, they can provide high treatment efficiencies of activated sludge systems with much lower energy inputs. Organic shock loads are handled well because large biomass is present. No bulking, foaming, or floating of sludge occurs and sludge has good settleability and dewaterability. Another advantage of RBC systems is the minimal labor requirement for operation and maintenance. Even though RBC systems have these advantages, their acceptance was slow mainly due to operational problems with the earlier units (such as shaft failures) and the lack of considerable design and operation data. A review of literature shows that there is only limited information available on the wastewater treatment with RBCs. Recently, there has been considerable contributions to the knowledge on RBC technology. However, information on the treatment of organic hazardous wastes using RBCs is still very limited. This paper reports that a considerable number of studies on the biological treatment of organic hazardous compounds was sponsored by U.S. Environmental Protection Agency (EPA). For example, an EPA sponsored study examined the effect of such compounds on the performance of activated sludge process. Bench-scale continuous-flow and batch units were used. Influent was settled municipal wastewater to which toxic compounds were added. In batch operations, 2-chlorophenol and pentachlorophenol caused an increase in the effluent Chemical Oxygen Demand (COD) at an influent concentration of 5 mg/L. No adverse effect of 2-nitrophenol on the batch system was reports. 2-Chlorophenol was one of the compounds that upset the performance of continuous-flow activated sludge units, yielding higher than normal levels of effluent suspended solids

Caracterización del proceso de adsorción de 3-cloro fenol desde solución acuosa sobre carbon activado por calorimetria de inmersión Characterization of 3-chlorophenol adsorption process from aqueous solution on activated carbon by immersion calorimetry

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Liliana Giraldo

2009-01-01

Full Text Available The immersion enthalpy of activated carbon in 3-chlorophenol solutions, of 100 mg L-1, is determined at different pH values between 3 and 11 with results between 37.6 and 21.2 J g-1. The 3-chlorophenol adsorbed quantities on the activated carbon during the calorimetric experience, are between 1.13 and 2.19 mg g-1, for different pH values of the solution. The 3-chlorophenol adsorbed quantity and the immersion enthalpy decrease by increasing of the pH solution, while increasing the adsorbed quantity increases the immersion enthalpy value.

Chronic exposure to chlorophenol related compounds in the pesticide production workplace and lung cancer: a meta-analysis.

Science.gov (United States)

Zendehdel, Rezvan; Tayefeh-Rahimian, Raana; Kabir, Ali

2014-01-01

Chlorophenols (CPs) and related phenoxyacetic acids (PAs) are pesticide groups contaminated with highly toxic 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) during production. PAs and CPs exposure is associated with risk of cancer, but the situation regarding lung cancer has not been clearly defined. We proposed a meta-analysis of published researches to evaluate relationship between chronic exposure to PAs and CPs in pesticide production workplaces and the risk of lung cancer. After searching PubMed, Scopus, Scholar Google, Web of Sciences until August 2013, the association between chronic PAs and CPs exposure in production workplace and lung cancer was studied in 15 cohort studies. The standardized mortality rate (SMR) and 95% confidence intervals (CI) were collected from the papers. We used random or fixed-effects models, Egger test, funnel plot and meta regression in our analysis. Five papers with six reports were included in the final analysis. The standardized mortality rate for lung cancer from the random model was 1.18 (95% CI: 1.03-1.35, p=0.014) with moderate heterogeneity. Publication bias was not found for included studies in meta-analysis (p=0.9). Our findings has strengthen the evidence of lung cancer from chronic exposure to chlorophenol related compounds (PAs, CPs).

EFFECT OF NATURAL IRON OXIDE, HYDROGEN PEROXIDE, AND OXALIC ACID ON PHOTOCHEMICAL DEGRADATION OF 2-CHLOROPHENOL

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W REMACHE

2014-07-01

Full Text Available The voluntary or accidental release of chemical compounds in the environment is a major cause of pollution of natural waters. Most of chlorophenols are toxic and hardly biodegradable and are difficult to remove from the environment. Therefore, it is important to find innovative and economical methods for the safe and complete destruction. The objective of this work is to test the activity photocatalytic of natural iron oxide (NIO in the photodegradation of 2-chlorophenol (2-CP. The analysis chromatographic with HPLC of solutions exposed under UV irradiation revealed that the degradation of 2-CP was negligible under the condition of using only natural iron oxide. The effect of wavelength on photoreactivity of NIO was also investigated in this process: at high wavelength thus at low energy the efficiency of degradation is important. We have also investigated the activation of NIO by hydrogen peroxide and oxalic acid, The results showed that the photodegradation of 2-CP under UVA irradiation could be enhanced greatly in the presence of oxalate. 2-CP was completly removed after 240 minutes of irradiation when the concentration of oxalic acid is equal to 2.10-3 M. The use of 2.0 % of isopropanol as a scavenger confirmed the intervention of hydroxyl radicals in the photodegradation of 2-CP.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate

International Nuclear Information System (INIS)

He Di; Guan Xiaohong; Ma Jun; Yang Xue; Cui Chongwei

2010-01-01

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai) > soil HAs > commercial HA (Fluka) > aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of C=C moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R 2 > 0.75) implied that π-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The π-π interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH = 7.0.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate.

Science.gov (United States)

He, Di; Guan, Xiaohong; Ma, Jun; Yang, Xue; Cui, Chongwei

2010-10-15

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai)>soil HAs>commercial HA (Fluka)>aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of CC moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R(2)>0.75) implied that pi-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The pi-pi interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH=7.0. 2010 Elsevier B.V. All rights reserved.

Influence of humic acids of different origins on oxidation of phenol and chlorophenols by permanganate

Energy Technology Data Exchange (ETDEWEB)

He Di, E-mail: hedy1997@hotmail.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Guan Xiaohong, E-mail: hitgxh@126.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Ma Jun, E-mail: majun@hit.edu.cn [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Yang Xue, E-mail: yangxue1_ok@163.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China); Cui Chongwei, E-mail: cuichongwei1991@126.com [State Key Lab of Urban Water Resource and Environment (HIT), Harbin Institute of Technology, Harbin (China)

2010-10-15

The influences of humic acids (HAs) of different origins, including two commercial HAs, three soil HAs and one aquatic HA, on phenols oxidation by permanganate were studied. The apparent second-order rate constants of 2-chlorophenol (2-CP)/phenol oxidation by permanganate in the presence of HAs at pH 7 followed the order of commercial HA (Shanghai) > soil HAs > commercial HA (Fluka) > aquatic HA. Moreover, the commercial HA (Shanghai) could accelerate the oxidation of different chlorophenols (CP) significantly under neutral condition. The FTIR analysis demonstrated greater content of C=C moieties and less amount of carboxylate, aliphatic groups and polysaccharide-like substances in soil HAs than in aqueous HA, suggesting that the increase of aromaticity in HA was beneficial to the oxidation of phenols by permanganate. The apparent second-order rate constants of 2-CP/phenol oxidation by permanganate in the presence of HAs correlated well with specific visible absorption (SVA) at 665 nm of HAs. High positive correlation coefficients (R{sup 2} > 0.75) implied that {pi}-electrons of HA strongly influenced the reactivity of 2-CP/phenol towards permanganate oxidation, which agreed well with positive correlation between Fluorescence Regional Integration (FRI) and the apparent second-order rate constants. The {pi}-{pi} interaction between HAs and phenols, the steric hindrance effect and the dissociation of phenols may affect the oxidation of phenols by permanganate in the presence of HA at pH = 7.0.

Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Habib, E-mail: bagheri@sharif.edu [Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Azadi Av., P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of); Aghakhani, Ali; Baghernejad, Masoud; Akbarinejad, Alireza [Environmental and Bio-Analytical Laboratories, Department of Chemistry, Sharif University of Technology, Azadi Av., P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of)

2012-02-24

A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100-200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2-10 ng L{sup -1}. The relative standard deviations (RSD) (n = 3) at the concentration level of 1.7-6.7 ng mL{sup -1} were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27-1330 ng L{sup -1} for phenol and monochlorophenols and 7-1000 ng L{sup -1} for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.

Cold Incineration of Chlorophenols in Aqueous Solution by Advanced Electrochemical Process Electro-Fenton. Effect of Number and Position of Chlorine Atoms on the Degradation Kinetics

Science.gov (United States)

Oturan, Nihal; Panizza, Marco; Oturan, Mehmet A.

2009-09-01

This study reports the kinetics of the degradation of several chlorophenols (CPs), such as monochlorophenols (2-chlorophenol and 4-chlorophenol), dichlorophenols (2,4-dichlorophenol and 2,6- dichlorophenol), trichlorophenols (2,3,5- trichlorophenol and 2,4,5-trichlorophenol), 2,3,5,6-tetrachlorophenol, and pentachlorophenol, by the electro-Fenton process using a carbon felt cathode and a Pt anode. The effect of number and the position of the chlorine atoms in the aromatic ring on the oxidative degradation rate was evaluated and discussed. The oxidation reaction of all the CPs with hydroxyl radicals evidenced a pseudo-first-order kinetics and the rate constant decreased with increasing the number of chlorine atoms. The absolute rate constant of second-order reaction kinetics between CPs and •OH was determined by the competition kinetics method in the range of (3.56-7.75) × 109 M-1 s-1 and follows the same sequence of the apparent rate constants. The mineralization of several CPs and of a mixture of all CPs under study was monitored by the total organic carbon (TOC) removal and the chlorine release during mineralization was followed by ion chromatography. Our results demonstrated that more chlorinated phenols are more difficult to mineralize; however for all the tested CPs, almost quantitative release of chloride ions was obtained after 6 h of treatment.

COMBINED BIOLOGICAL-PHOTOCATALYTIC TREATMENT FOR THE MINERALIZATION OF A MIXTURE OF CHLOROPHENOLS IN AN ELECTROLYTE-CONTAINING MODEL WATER AND SPONTANEOUS SEDIMENTATION OF TITANIUM DIOXIDE

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Dhanus Suryaman

2010-06-01

Full Text Available To shorten the biological treating time and to examine the effect of electrolytes in a model water on the photocatalytic treatment, the combined biological-photocatalytic treatment was evaluated for removal of a mixture (total: 100 mg L-1, each: 25 mg L-1 of 2-chlorophenol (2-CP, 2,4-dichlorophenol (2,4-DCP, 2,4,5-trichlorophenol (2,4,5-TCP, and pentachlorophenol (PCP in tap water. The mineralization of the four phenols was performed by a flow (biological treatment-circulative flow (photocatalytic treatment operation under black light and sunlight irradiations. After a large portion of biodegradable 2-CP and 2,4-DCP, and around half amount of slightly biodegradable 2,4,5-TCP were removed by the biological treatment, the remained three chlorophenols, biorecalcitrant PCP, and  biodegradation products were completely removed by the subsequent photocatalytic treatment. The combined treatment significantly shortened the degradation time only the biotreatment. High circulative flow rate (600 mL min-1 enabled for TiO2 particles to completely suspend in a tubular photoreactor and resulted in high removals of chlorophenols and TOC. Sunlight irradiation was successfully used and the saving of the electric energy of black light was possible. Since TiO2 particles in the tap water spontaneously sedimented on standing after the photocatalytic treatment, the combined system can be operated by integrating it with the TiO2 separation.   Keywords: photocatalysis, titanium dioxide, biodegradation, pollutant, wastewater

Aqueous hydrodechlorination of 4-chlorophenol over an Rh/reduced graphene oxide synthesized by a facile one-pot solvothermal process under mild conditions

International Nuclear Information System (INIS)

Ren, Yanlin; Fan, Guangyin; Wang, Chenyu

2014-01-01

Graphical abstract: The Rh nanoparticles/reduced graphene oxide (Rh NPs/RGO) nanocatalyst synthesized by a solvothermal technique showed high activity and stability for the hydrodechlorination of 4-chlorophenol under mild conditions. - Highlights: • Rh/RGO was synthesized through a one-pot polyol reduction of GO and RhCl 3 . • Complete HDC of 4-chlorophenol was obtained in aqueous phase without any additive. • The Rh/RGO exhibited an excellent catalytic performance for HDC reaction. - Abstract: Reduced graphene oxide (RGO) supported rhodium nanoparticles (Rh-NPs/RGO) was synthesized through one-pot polyol co-reduction of graphene oxide (GO) and rhodium chloride. The catalytic property of Rh-NPs/RGO was investigated for the aqueous phase hydrodechlorination (HDC) of 4-chlorophenol (4-CP). A complete conversion of 4-CP into high valued products of cyclohexanone (selectivity: 23.2%) and cyclohexanol (selectivity: 76.8%) was successfully achieved at 303 K and balloon hydrogen pressure in a short reaction time of 50 min when 1.5 g/L of 4-CP was introduced. By comparing with Rh-NPs deposited on the other supports, Rh-NPs/RGO delivered the highest initial rate (111.4 mmol/g Rh min) for 4-CP HDC reaction under the identical conditions. The substantial catalytic activity of Rh-NPs/RGO can be ascribed to the small and uniform particle size of Rh (average particle size was 1.7 ± 0.14 nm) on the surface of the RGO sheets and an electron-deficient state of Rh in the catalyst as a result of the strong interaction between the active sites and the surface function groups of RGO

Amorphous TiO2 doped with carbon for visible light photodegradation of rhodamine B and 4-chlorophenol

International Nuclear Information System (INIS)

Shao, Penghui; Tian, Jiayu; Zhao, Zhiwei; Shi, Wenxin; Gao, Shanshan; Cui, Fuyi

2015-01-01

Graphical abstract: - Highlights: • Amorphous TiO 2 doped with carbon is prepared as a visible photocatalyst. • RhB and 4-chlorophenol are decomposed effectively by carbon-doped amorphous TiO 2 . • The mechanism for visible light photocatalysis is discussed detailedly. - Abstract: Visible light photocatalytic activity of amorphous TiO 2 doped with carbon is prepared by a facile sol-gel route for the first time. The most active sample with mesostructure of amorphous phase, high surface area (273 m 2 g −1 ) and large pore volume (0.33 cm 3 g −1 ) is identified by X-ray diffractometer, Raman spectrometer, transmission electron microscope and N 2 adsorption–desorption isotherms. In addition, the most active sample is characterized by Fourier transform-infrared spectrometer, X-ray photoelectron spectrometer, UV–vis diffuse reflectance spectrometer and luminescence spectrometer. The results show that the most active sample with oxygenic groups has a narrower bandgap and lower recombination of electron–hole, due to the carbon doping and phase of amorphous. Effective photodegradation capability and stability of rhodamine B and colorless 4-chlorophenol are verified by photocatalytic tests under visible light irradiation. A possible mechanism of amorphous TiO 2 doped with carbon for visible light photocatalysis is proposed. The findings of this paper will provide new insights to design visible light-induced photocatalyst based on amorphous TiO 2 for organic removal

Bioremediation of 2-chlorophenol containing wastewater by aerobic granules-kinetics and toxicity

Energy Technology Data Exchange (ETDEWEB)

Khan, Mohammad Zain [Environmental Research Laboratory, Department of chemistry, Aligarh Muslim University, Faculty of Science, Aligarh 202002, UP (India); Mondal, Pijush Kanti, E-mail: pijushamu@gmail.com [Environmental Research laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh 202002, UP (India); Sabir, Suhail, E-mail: sabirsuhail09@gmail.com [Environmental Research Laboratory, Department of chemistry, Aligarh Muslim University, Faculty of Science, Aligarh 202002, UP (India)

2011-06-15

Highlights: {yields} 2-Chlorophenol degrading aerobic granules were cultivated in sequencing batch reactor in presence of glucose and the organic loading rate (OLR) was increased from 6.9 to 9.7 kg COD m{sup -3} d{sup -1} during the experiment. {yields} Spectral studies confirmed that the biodegradation occurs via chlorocatechol pathway and modified ortho-cleavage. {yields} Biodegradation kinetics of 2-CP followed the Haldane model with kinetic parameters (R{sup 2} > 0.9) V{sub max} = 840 mg2-CP gMLVSS{sup -1} d{sup -1}, K{sub s} = 24.61 mg L{sup -1}, K{sub i} = 315.02 mg L{sup -1}. {yields} Genotoxic examination by plasmid nicking assay confirmed that the effluent was non-toxic. - Abstract: 2-Chlorophenol (2-CP) degrading aerobic granules were cultivated in a sequencing batch reactor (SBR) in presence of glucose. The organic loading rate (OLR) was increased from 6.9 to 9.7 kg COD m{sup -3} d{sup -1} (1150-1617 mg L{sup -1}COD per cycle) during the experiment. The alkalinity (1000 mg L{sup -1} as CaCO{sub 3}) was maintained throughout the experiment. The specific cell growth rate was found to be 0.013 d{sup -1}. A COD removal efficiency of 94% was achieved after steady state at 8 h HRT (hydraulic retention time). FTIR, UV, GC, GC/MS studies confirmed that the biodegradation of 2-CP occurs via chlorocatechol (modified ortho-cleavage) pathway. Biodegradation kinetics followed the Haldane model with kinetic parameters: V{sub max} = 840 mg2-CP gMLVSS{sup -1} d{sup -1}, K{sub s} = 24.61 mg L{sup -1}, K{sub i} = 315.02 mg L{sup -1}. Abiotic losses of 2-CP due to volatilization and photo degradation by sunlight were less than 3% and the results of genotoxicity showed that the degradation products are eco-friendly.

Sorption of 2-Chlorophenol from aqueous solutions by functionalized cross-linked polymers

Directory of Open Access Journals (Sweden)

Rodrigo Martins Fráguas

2013-01-01

Full Text Available This manuscript describes the synthesis of three polymers based on styrene (STY, divinylbenzene (DVB and two different vinyl monomers: methyl methacrylate (MMA and acrylonitrile (AN. The STY-DVB, STY-DVB-MMA and STY-DVB-AN polymers were synthesized employing the aqueous suspension technique. Reaction yields were 73%, 81% and 75%, respectively. They were morphological and chemically characterized using different techniques. The extraction capacity of the polymers was evaluated using 2-chlorophenol. The polymer extraction capacities were evaluated varying contact time the (1 h, 3 h and 5 h, temperature (30 °C, 35 °C and 40 °C, and pH (3, 5.6 and 8. The STY-DVB-AN polymer was the most efficient; it removed around 95% of the analyte using a contact time 50 h.

Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

International Nuclear Information System (INIS)

Bagheri, Habib; Aghakhani, Ali; Baghernejad, Masoud; Akbarinejad, Alireza

2012-01-01

A novel solid phase microextraction (SPME) fiber was fabricated by electrospinning method in which a polymeric solution was converted to nanofibers using high voltages. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three dimensional structure. Polyamide (nylon 6), due to its suitable characteristics was used to prepare the unbreakable SPME nanofiber. The scanning electron microscopy (SEM) images of this new coating showed a diameter range of 100–200 nm for polyamide nanofibers with a homogeneous and porous surface structure. The extraction efficiency of new coating was investigated for headspace solid-phase microextraction (HS-SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography–mass spectrometry (GC–MS) analysis. Effect of different parameters influencing the extraction efficiency including extraction temperature, extraction time, ionic strength and polyamide amount were investigated and optimized. In order to improve the chromatographic behavior of phenolic compounds, all the analytes were derivatized prior to the extraction process using basic acetic anhydride. The detection limits of the method under optimized conditions were in the range of 2–10 ng L −1 . The relative standard deviations (RSD) (n = 3) at the concentration level of 1.7–6.7 ng mL −1 were obtained between 1 and 7.4%. The calibration curves of chlorophenols showed linearity in the range of 27–1330 ng L −1 for phenol and monochlorophenols and 7–1000 ng L −1 for dichloro and trichlorophenols. Also, the proposed method was successfully applied to the extraction of phenol and chlorophenols from real water samples and relative recoveries were between 84 and 98% for all the selected analytes except for 2,4,6 tricholophenol which was between 72 and 74%.

Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Tu, Yuting [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France); School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Xiong, Ya; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275 (China); Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Descorme, Claude, E-mail: claude.descorme@ircelyon.univ-lyon1.fr [Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), CNRS – Université Claude Bernard Lyon 1, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex (France)

2014-07-15

Highlights: • A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared. • FeSC exhibited high catalytic activity in the wet air oxidation of 2-chlorophenol. • A strong correlation was observed between the 2-CP conversion, the iron leaching and the pH. • Using an acetate buffer, the iron leaching was suppressed while keeping some catalytic activity. • A simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst. - Abstract: A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pH{sub PZC}, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120 °C under 0.9 MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5 h and 90% Total Organic Carbon (TOC) was removed after 24 h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

[Degradation of 4-chlorophenol in aqueous solution by high-voltage pulsed discharge-ozone technology].

Science.gov (United States)

Wen, Yuezhong; Jiang, Xuanzhen; Liu, Weiping

2002-03-01

The combination of high voltage pulse discharge and ozonation as an advanced oxidation technology was used to investigate the degradation of 4-chlorophenol (4-CP) in water. The factors that affect the rate of degradation were discussed. The 1.95 x 10(-3) mol/L solutions of 4-CP were almost completely (96%) degraded after the discharge treatment of 30 min. The degradation of 4-CP was investigated as a function of the ozone concentration, radical scavenger and electrode distance. The rate of 4-CP degradation increases with an increase in ozone concentration and a decrease in the electrode distance from 20 mm to 10 mm. The presence of radical scavenger decreased the rate of 4-CP degradation.

p-Chlorophenol adsorption on activated carbons with basic surface properties

Science.gov (United States)

Lorenc-Grabowska, Ewa; Gryglewicz, Grażyna; Machnikowski, Jacek

2010-05-01

The adsorption of p-chlorophenol (PCP) from aqueous solution on activated carbons (ACs) with basic surface properties has been studied. The ACs were prepared by two methods. The first method was based on the modification of a commercial CWZ AC by high temperature treatment in an atmosphere of ammonia, nitrogen and hydrogen. The second approach comprised the carbonization followed by activation of N-enriched polymers and coal tar pitch using CO 2 and steam as activation agent. The resultant ACs were characterized in terms of porous structure, elemental composition and surface chemistry (pH PZC, acid/base titration, XPS). The adsorption of PCP was carried out from an aqueous solution in static conditions. Equilibrium adsorption isotherm was of L2 type for polymer-based ACs, whereas L3-type isotherm was observed for CWZ ACs series. The Langmuir monolayer adsorption capacity was related to the porous structure and the amount of basic sites. A good correlation was found between the adsorption capacity and the volume of micropores with a width water molecule adsorption on the PCP uptake is discussed.

The enhanced photoactivity of nanosized Bi2WO6 catalyst for the degradation of 4-chlorophenol

International Nuclear Information System (INIS)

Fu Hongbo; Yao Wenqing; Zhang Liwu; Zhu Yongfa

2008-01-01

Nanosized Bi 2 WO 6 catalyst exhibited the enhanced photoactivity for the degradation of 4-chlorophenol (4-CP) under visible irradiation compared to the sample prepared by high-temperature solid reaction. The photoactivity of the catalyst was sensitive to pH variation of the suspension. Nanosized Bi 2 WO 6 catalyst showed the highest activity at pH 7.2. The photodegradation of 4-CP by nanosized Bi 2 WO 6 catalyst followed a pseudo-first-order reaction. After three recycling runs for the photodegradation of 4-CP, the activity of the catalyst did not show any significant loss, suggesting that the catalyst was stable under visible irradiation

PENGUJIAN AKTIVITAS KOMPOSIT Fe2O3-SiO2 SEBAGAI FOTOKATALIS PADA FOTODEGRADASI 4-KLOROFENOL (The Activity Test of Fe2O3-SiO2 Composite As Photocatalyst on 4-Chlorophenol Photodegradation

Directory of Open Access Journals (Sweden)

Eko Sri Kunarti

2009-03-01

Full Text Available ABSTRAK  Pada penelitian ini telah dilakukan pengujian aktivitas komposit Fe2O3-SiO2 sebagai fotokatalis pada fotodegradasi 4-klorofenol. Penelitian diawali dengan preparasi dan karakterisasi fotokatalis Fe2O3-SiO2. Preparasi dilakukan dengan metode sol-gel pada temperatur kamar menggunakan tetraetil ortosilikat (TEOS dan besi (III nitrat sebagai prekursor diikuti dengan perlakuan termal pada temperature 500 oC. Karakterisasi dilakukan dengan metode spektrometri inframerah, difraksi sinar-X dan spektrometri fluoresensi sinar-X. Uji aktivitas komposit untuk fotodegradasi 4-klorofenol dilakukan dalam reaktor tertutup yang dilengkapi dengan lampu UV. Pada uji ini telah dipelajari pengaruh waktu penyinaran dan pH larutan terhadap efektivitas fotodegradasi 4-klorofenol. Hasil penelitian menunjukkan bahwa komposit Fe2O3-SiO2 dapat dipreparasi dengan metode sol-gel pada temperatur kamar diikuti perlakuan termal. Komposit Fe2O3-SiO2 dapat meningkatkan efektivitas fotodegradasi 4-klorofenol dari 11,86 % menjadi 55,38 %. Efektivitas fotodegradasi 4- klorofenol dipengaruhi waktu penyinaran dan pH larutan yang semakin lama waktu penyinaran efektifitas fotodegradasi semakin tinggi, namun waktu penyinaran yang lebih lama dari 4 jam dapat menurunkan efektivitasnya. pH larutan memberikan pengaruh yang berbeda-beda pada efektivitas fotodegradasi 4-klorofenol.   ABSTRACT The activity test of Fe2O3-SiO2 composite as photocatalyst on 4-chlorophenol photodegradation has been studied. The research was initiated by preparation of Fe2O3-SiO2 photocatalyst and followed by characterization. The preparation was conducted by sol-gel method at room temperature using tetraethylorthosilicate (TEOS and iron (III nitrate as precursors followed by thermal treatment at a temperature of 500oC. The characterizations were performed by X-ray Diffraction (XRD, Infrared and X-ray Fluorescence Spectrophotometry. The photocatalytic activity test of composites for 4 chlorophenol

Spectroscopic studies of some lanthanide(III nitrate complexes synthesized from a new ligand 2,6-bis-(salicylaldehyde hydrazone-4-chlorophenol

Directory of Open Access Journals (Sweden)

A.S. Sall

2003-06-01

Full Text Available The ligand 2,6-bis-(salicylaldehydehydrazone-4-chlorophenol (H5L and its binuclear lanthanide(III nitrate complexes {[Ln2(H4L3(NO3](NO32.mH2O} where Ln = La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb and Y, have been synthesized. The complexes were characterized by chemical analysis, conductance, magnetic moment measurements and infrared spectra. Infrared study indicates that the ligand behaves both as neutral and ionic O donors and as neutral N donors.

Comparison of different chlorophenols degradation in aqueous solutions by gamma irradiation under reducing conditions

International Nuclear Information System (INIS)

Peng, Yunxia; He, Shijun; Wang, Jianlong; Gong, Wenqi

2012-01-01

The reductive degradation of chlorophenols (CPs), including 2-CP, 4-CP and 2,4-DCP by gamma irradiation was investigated and compared. The results showed that the most efficient degradation took place with 2,4-DCP, followed by 2-CP and then 4-CP. This confirmed that the number and position of chlorine atoms existing in the benzene ring have significant impact on dechlorination and decomposition of CPs. The G-values of decomposition of CPs, the formation of intermediate products and chloride ion, and the degradation rate (K CPs and K Cl −1 ) were also determined. - Highlights: ► Reductive degradation of 2-CP, 4-CP and 2,4-DCP by γ radiation was compared. ► Number and position of chlorine affect their dechlorination and decomposition. ► G-values of CPs decomposition, intermediate formation and chloride release were determined.

Photochemical transformation of anionic 2-nitro-4-chlorophenol in surface waters: Laboratory and model assessment of the degradation kinetics, and comparison with field data

Energy Technology Data Exchange (ETDEWEB)

Sur, Babita [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 5, 10125 Torino (Italy); Department of Chemical Engineering, Calcutta University, 92 Acharya P. C. Road, Kolkata 700009 (India); De Laurentiis, Elisa; Minella, Marco; Maurino, Valter; Minero, Claudio [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 5, 10125 Torino (Italy); Vione, Davide [Dipartimento di Chimica, Universita di Torino, Via P. Giuria 5, 10125 Torino (Italy); Centro Interdipartimentale NatRisk, Universita di Torino, Via Leonardo da Vinci 44, 10095 Grugliasco (Italy)

2012-06-01

Anionic 2-nitro-4-chlorophenol (NCP) may occur in surface waters as a nitroderivative of 4-chlorophenol, which is a transformation intermediate of the herbicide dichlorprop. Here we show that NCP would undergo efficient photochemical transformation in environmental waters, mainly by direct photolysis and reaction with {center_dot}OH. NCP has a polychromatic photolysis quantum yield {Phi}{sub NCP} = (1.27 {+-} 0.22) {center_dot} 10{sup -5}, a rate constant with {center_dot}OH k{sub NCP,}{center_dot}{sub OH} = (1.09 {+-} 0.09) {center_dot} 10{sup 10} M{sup -1} s{sup -1}, a rate constant with {sup 1}O{sub 2}k{sub NCP,1O2} = (2.15 {+-} 0.38) {center_dot} 10{sup 7} M{sup -1} s{sup -1}, a rate constant with the triplet state of anthraquinone-2-sulphonate k{sub NCP,3AQ2S*} = (5.90 {+-} 0.43) {center_dot} 10{sup 8} M{sup -1} s{sup -1}, and is poorly reactive toward CO{sub 3}{sup -}{center_dot}. The k{sub NCP,3AQ2S*} value is representative of reaction with the triplet states of chromophoric dissolved organic matter. The inclusion of photochemical reactivity data into a model of surface-water photochemistry allowed the NCP transformation kinetics to be predicted as a function of water chemical composition and column depth. Very good agreement between model predictions and field data was obtained for the shallow lagoons of the Rhone delta (Southern France). Highlights: Black-Right-Pointing-Pointer Phototransformation kinetics of 2-nitro-4-chlorophenol, relevant to surface waters. Black-Right-Pointing-Pointer Determination of photochemical reactivity data in the laboratory. Black-Right-Pointing-Pointer Model approach to combine photochemical reactivity with environmental variables. Black-Right-Pointing-Pointer Good agreement with field data in lagoon water (Rhone delta, Southern France). Black-Right-Pointing-Pointer Direct photolysis and reaction with {center_dot}OH as main photoprocesses in the environment.

A novel sol-gel-based amino-functionalized fiber for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Habib [Department of Chemistry, Sharif University of Technology, P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of)], E-mail: Bagheri@sharif.edu; Babanezhad, Esmaeil; Khalilian, Faezeh [Department of Chemistry, Sharif University of Technology, P.O. Box 11365-9516, Tehran (Iran, Islamic Republic of)

2008-05-26

A novel amino-functionalized polymer was synthesized using 3-(trimethoxysilyl) propyl amine (TMSPA) as precursor and hydroxy-terminated polydimethylsiloxane (OH-PDMS) by sol-gel technology and coated on fused-silica fiber. The synthesis was designed in a way to impart polar moiety into the coating network. The scanning electron microscopy (SEM) images of this new coating showed the homogeneity and the porous surface structure of the film. The efficiency of new coating was investigated for headspace solid-phase microextraction (SPME) of some environmentally important chlorophenols from aqueous samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effect of different parameters influencing the extraction efficiency such as extraction temperature, extraction time, ionic strength and pH was investigated and optimized. In order to improve the separation efficiency of phenolic compounds on chromatography column all the analytes were derivatized prior to extraction using acetic anhydride at alkaline condition. The detection limits of the method under optimized conditions were in the range of 0.02-0.05 ng mL{sup -1}. The relative standard deviations (R.S.D.) (n = 6) at a concentration level of 0.5 ng mL{sup -1} were obtained between 6.8 and 10%. The calibration curves of chlorophenols showed linearity in the range of 0.5-200 ng mL{sup -1}. The proposed method was successfully applied to the extraction from spiked tap water samples and relative recoveries were higher than 90% for all the analytes.

Photoelectron and UV absorption spectroscopy for determination of electronic configurations of negative molecular ions: Chlorophenols

International Nuclear Information System (INIS)

Tseplin, E.E.; Tseplina, S.N.; Tuimedov, G.M.; Khvostenko, O.G.

2009-01-01

The photoelectron and UV absorption spectra of p-, m-, and o-chlorophenols in the gas phase have been obtained. On the basis of DFT B3LYP/6-311++G(d, p) calculations, the photoelectron bands have been assigned to occupied molecular orbitals. From the TDDFT B3LYP/6-311++G(d, p) calculation results, the UV absorption bands have been assigned to excited singlet states of the molecules under investigation. For each excited state a dominant transition was found. It has been shown that the energies of these singlet transitions correlate with the energy differences between the ground-state molecular orbitals participating in them. Using the UV spectra interpretation, the electronic states of molecular anions detected earlier for the same compounds by means of the resonant electron capture mass-spectrometry have been determined.

A field-practical assay for rapid detection of chlorophenols

Energy Technology Data Exchange (ETDEWEB)

Washburn, K.S.; Phillips, T.D. [Texas A and M Univ., College Station, TX (United States). Dept. of Veterinary Anatomy and Public Health

1994-12-31

Water-solvated chlorophenols (CPs) are environmental toxins associated with wood preservation and pesticide synthesis and usage. Their toxicity and association with dioxin-contaminated wastes are well-documented, as is their stability in most environmental settings. Several analytical procedures, mainly HPLC and GC/MS, are currently used to detect and quantify CPs, but these procedures are based on expensive equipment and technical expertise in a laboratory setting. The authors have developed an inexpensive, field-practical method for CPs, utilizing a small, packed glass minicolumn and derivatization of target CP molecules with dansyl chloride (5-dimethylaminonaphthalene-1sulfonyl chloride), or DsCl. A nonfluorescent borosilicate glass tube was used to house an array of inorganic sorbent materials, including preparative layers and a reactive neutral alumina interface separated by sand. DsCl is a substituted naphthalene with a conjugated X system that is responsible for its fluorescent complexation. Amines that reacted with DsCl were removed with a small amount of phyllosilicate clay to avoid interference. A neutral alumina/sand interface was used to strongly bind and immobilize the dansylated CPs. Activities greater than 3.0 for the alumina were avoided to prevent loss of selectivity, intensity and color of the fluorescence at the reactive interface. The results indicated that this assay was capable of rapidly screening potable water samples and detecting CP contamination at very low concentrations (i.e., 1.0 ppb of pentachlorophenol in drinking water).

Enhanced chlorophenol sorption of soils by rice-straw-ash amendment

International Nuclear Information System (INIS)

Liu, Jen-Chyi; Tzou, Yu-Min; Lu, Yi-Hsien; Wu, Jeng-Tzung; Cheng, Mei-Ping; Wang, Shan-Li

2010-01-01

Rice-straw burning is a common post-harvest practice on rice paddy land, which results in the accumulation of rice-straw ash (RSA) in paddy soil. Because the occurrence of RSA in soil may affect the fate and transport of contaminants, this study investigated the sorption of 3-chlorophenol (3-CP) on RSA and RSA amended soils to evaluate the sorptive properties of RSA in soils. The results showed that the sorption of 3-CP to RSA proceeds through a surface reaction rather than through partitioning and that the neutral form of 3-CP is preferentially sorbed to the surface when compared to the deprotonated anionic form of 3-CP. The addition of RSA to the soils enhanced the overall 3-CP sorption, indicating that RSA amendment may be applied to retard the movement of 3-CP in contaminated soils. As the RSA content in the soils was increased from 0% to 2%, the Langmuir sorption maximum of the soils increased from 18-80 to 256-274 mg kg -1 . Thus, RSA contributed more to the total sorption of the soils than other major components in the soils. Nonetheless, the 3-CP sorption of the soils containing RSA was less than the combination of pure RSA and the soils, thereby indicating that the 3-CP sorption of RSA was suppressed. This may be attributed to the competition of organic matter or other soil components for the surface binding sites of RSA.

Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts

International Nuclear Information System (INIS)

Li Ning; Descorme, Claude; Besson, Michele

2007-01-01

A series of noble metal (Pt, Pd, Ru) loaded zirconia catalysts were evaluated in the catalytic wet air oxidation (CWAO) of mono-chlorophenols (2-CP, 3-CP, 4-CP) under relatively mild reaction conditions. Among the investigated noble metals, Ru appeared to be the best to promote the CWAO of CPs as far as incipient-wetness impregnation was used to prepare all the catalysts. The position of the chlorine substitution on the aromatic ring was also shown to have a significant effect on the CP reactivity in the CWAO over 3 wt.% Ru/ZrO 2 . 2-CP was relatively easier to degradate compared to 3-CP and 4-CP. One reason could be the higher adsorption of 2-CP on the catalyst surface. Further investigations suggested that 3 wt.% Ru/ZrO 2 is a very efficient catalyst in the CWAO of 2-CP as far as high 2-CP conversion and TOC abatement could still be reached at even lower temperature (393 K) and lower total pressure (3 MPa). Additionally, the conversion of 2-CP was demonstrated to increase with the initial pH of the 2-CP solution. The dechlorination reaction is promoted at higher pH. In all cases, the adsorption of the reactants and the reaction intermediates was shown to play a major role. All parameters that would control the molecule speciation in solution or the catalyst surface properties would have a key effect

Development of an energy-saving anaerobic hybrid membrane bioreactors for 2-chlorophenol-contained wastewater treatment.

Science.gov (United States)

Wang, Yun-Kun; Pan, Xin-Rong; Sheng, Guo-Ping; Li, Wen-Wei; Shi, Bing-Jing; Yu, Han-Qing

2015-12-01

A novel energy-saving anaerobic hybrid membrane bioreactor (AnHMBR) with mesh filter, which takes advantage of anaerobic membrane bioreactor and fixed-bed biofilm reactor, is developed for low-strength 2-chlorophenol (2-CP)-contained wastewater treatment. In this system, the anaerobic membrane bioreactor is stuffed with granular activated carbon to construct an anaerobic hybrid fixed-bed biofilm membrane bioreactor. The effluent turbidity from the AnHMBR system was low during most of the operation period, and the chemical oxygen demand and 2-CP removal efficiencies averaged 82.3% and 92.6%, respectively. Furthermore, a low membrane fouling rate was achieved during the operation. During the AnHMBR operation, the only energy consumption was for feed pump. And a low energy demand of 0.0045-0.0063kWhm(-3) was estimated under the current operation conditions. All these results demonstrated that this novel AnHMBR is a sustainable technology for treating 2-CP-contained wastewater. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced degradation of p-chlorophenol in a novel pulsed high voltage discharge reactor.

Science.gov (United States)

Bian, Wenjuan; Ying, Xiangli; Shi, Junwen

2009-03-15

The yields of active specie such as ozone, hydrogen peroxide and hydroxyl radical were all enhanced in a novel discharge reactor. In the reactor, the original formation rate of hydroxyl radical was 2.27 x 10(-7) mol L(-1)s(-1), which was about three times than that in the contrast reactor. Ozone was formed in gas-phase and was transferred into the liquid. The characteristic of mass transfer was better in the novel reactor than that in the contrast reactor, which caused much higher ozone concentration in liquid. The dissociation of hydrogen peroxide was more evident in the former, which promoted the formations of hydroxyl radical. The p-chlorophenol (4-CP) degradation was also enhanced. Most of the ozone transferred into the liquid and hydrogen peroxide generated by discharge could be utilized by the degradation process of 4-CP. About 97% 4-CP was removed in 36 min discharge in the novel reactor. Organic acids such as formic, acetic, oxalic, propanoic and maleic acid were generated and free chloride ions were released in the degradation process. With the formation of organic acid, the pH was decreased and the conductivity was increased.

Enhanced degradation of p-chlorophenol in a novel pulsed high voltage discharge reactor

Energy Technology Data Exchange (ETDEWEB)

Bian Wenjuan [School of Chemistry and Chemical Engineering, Soochow University, Suzhou 215123 (China)], E-mail: bwenjuan@suda.edu.cn; Ying Xiangli; Shi Junwen [School of Chemistry and Chemical Engineering, Soochow University, Suzhou 215123 (China)

2009-03-15

The yields of active specie such as ozone, hydrogen peroxide and hydroxyl radical were all enhanced in a novel discharge reactor. In the reactor, the original formation rate of hydroxyl radical was 2.27 x 10{sup -7} mol L{sup -1} s{sup -1}, which was about three times than that in the contrast reactor. Ozone was formed in gas-phase and was transferred into the liquid. The characteristic of mass transfer was better in the novel reactor than that in the contrast reactor, which caused much higher ozone concentration in liquid. The dissociation of hydrogen peroxide was more evident in the former, which promoted the formations of hydroxyl radical. The p-chlorophenol (4-CP) degradation was also enhanced. Most of the ozone transferred into the liquid and hydrogen peroxide generated by discharge could be utilized by the degradation process of 4-CP. About 97% 4-CP was removed in 36 min discharge in the novel reactor. Organic acids such as formic, acetic, oxalic, propanoic and maleic acid were generated and free chloride ions were released in the degradation process. With the formation of organic acid, the pH was decreased and the conductivity was increased.

Enhanced degradation of p-chlorophenol in a novel pulsed high voltage discharge reactor

International Nuclear Information System (INIS)

Bian Wenjuan; Ying Xiangli; Shi Junwen

2009-01-01

The yields of active specie such as ozone, hydrogen peroxide and hydroxyl radical were all enhanced in a novel discharge reactor. In the reactor, the original formation rate of hydroxyl radical was 2.27 x 10 -7 mol L -1 s -1 , which was about three times than that in the contrast reactor. Ozone was formed in gas-phase and was transferred into the liquid. The characteristic of mass transfer was better in the novel reactor than that in the contrast reactor, which caused much higher ozone concentration in liquid. The dissociation of hydrogen peroxide was more evident in the former, which promoted the formations of hydroxyl radical. The p-chlorophenol (4-CP) degradation was also enhanced. Most of the ozone transferred into the liquid and hydrogen peroxide generated by discharge could be utilized by the degradation process of 4-CP. About 97% 4-CP was removed in 36 min discharge in the novel reactor. Organic acids such as formic, acetic, oxalic, propanoic and maleic acid were generated and free chloride ions were released in the degradation process. With the formation of organic acid, the pH was decreased and the conductivity was increased

Chlorophenol and alkylphenol concentrations in sediment and mussel tissues collected from selected locations in Kentucky Lake, USA

Energy Technology Data Exchange (ETDEWEB)

Loganathan, B.; Brown, B.; Owen, D. [Murray State Univ., Murray, KY (United States); Sajwan, K. [Savannah State Univ., Savannah, GA (United States)

2004-09-15

Kentucky (KY) Lake is one the major human-constructed lakes in the US. It serves as an ultimate repository of substances entering this watershed from portions of seven southeastern states, which include a sizeable fraction of the U.S. chemical processing, agricultural chemical products and electronics manufacturing industries. Although a few studies have examined the levels of chlorinated organics in the KY Lake and the lowermost Tennessee River, there have been no reports on the distribution on the levels of chlorophenols and alkylphenols in sediment and/or biological tissues from this region. In this study, sediment, and freshwater mussels were collected from selected locations in KY Lake and Lake Barkley and analyzed for CPs and APs. Furthermore, wood samples from abandoned docks, navigational towers and wood found in the lake bottom were also analyzed to examine the sources of CPs to the lakes.

Oxidative degradation of chlorophenol derivatives promoted by microwaves or power ultrasound: a mechanism investigation.

Science.gov (United States)

Cravotto, Giancarlo; Binello, Arianna; Di Carlo, Stefano; Orio, Laura; Wu, Zhi-Lin; Ondruschka, Bernd

2010-03-01

Phenols are the most common pollutants in industrial wastewaters (particularly from oil refineries, resin manufacture, and coal processing). In the last two decades, it has become common knowledge that they can be effectively destroyed by nonconventional techniques such as power ultrasound (US) and/or microwave (MW) irradiation. Both techniques may strongly promote advanced oxidation processes (AOPs). The present study aimed to shed light on the effect and mechanism of US- and MW-promoted oxidative degradation of chlorophenols; 2,4-dichlorophenoxyacetic acid (2,4-D), a pesticide widespread in the environment, was chosen as the model compound. 2,4-D degradation by AOPs was carried out either under US (20 and 300 kHz) in aqueous solutions (with and without the addition of Fenton reagent) or solvent-free under MW with sodium percarbonate (SPC). All these reactions were monitored by gas chromatography-mass spectrometry (GC-MS) analysis and compared with the classical Fenton reaction in water under magnetic stirring. The same set of treatments was also applied to 2,4-dichlorophenol (2,4-DCP) and phenol, the first two products that occur a step down in the degradation sequence. Fenton and Fenton-like reagents were employed at the lowest active concentration. The effects of US and MW irradiation were investigated and compared with those of conventional treatments. Detailed mechanisms of Fenton-type reactions were suggested for 2,4-D, 2,4-DCP, and phenol, underlining the principal degradation products identified. MW-promoted degradation under solvent-free conditions with solid Fenton-like reagents (viz. SPC) is extremely efficient and mainly follows pyrolytic pathways. Power US strongly accelerates the degradation of 2,4-D in water through a rapid generation of highly reactive radicals; it does not lead to the formation of more toxic dimers. We show that US and MW enhance the oxidative degradation of 2,4-D and that a considerable saving of oxidants and cutting down of

An adsorption diffusion model for removal of para-chlorophenol by activated carbon derived from bituminous coal.

Science.gov (United States)

Sze, M F F; McKay, G

2010-05-01

Batch adsorption experiments were carried out to study the adsorptive removal and diffusion mechanism of para-chlorophenol (p-CP) onto Calgon Filtrasorb 400 (F400) activated carbon. The external mass transfer resistance is negligible in the adsorption process carried out under different conditions in batch operation. Intraparticle diffusion model plots were used to correlate the batch p-CP adsorption data; three distinct linear sections were obtained for every batch operation. The textural properties of F400 activated carbon showed that it has a large portion of supermicropores, which is comparable to the size of the p-CP molecules. Due to the stronger interactions between p-CP molecules and F400 micropores, p-CP molecules predominantly diffused and occupied active sites in micropore region by hopping mechanism, and eventually followed by a slow filling of mesopores and micropores. This hypothesis is proven by the excellent agreement of the intraparticle diffusion model plots and the textural properties of F400 activated carbon. Copyright 2009 Elsevier Ltd. All rights reserved.

Fabrication of a novel PbO2 electrode with a graphene nanosheet interlayer for electrochemical oxidation of 2-chlorophenol

International Nuclear Information System (INIS)

Duan, Xiaoyue; Zhao, Cuimei; Liu, Wei; Zhao, Xuesong; Chang, Limin

2017-01-01

Highlights: • A novel PbO 2 electrode with a GNS interlayer (GSN-PbO 2 ) was prepared. • The GNS interlayer reduced grain size of β-PbO 2 crystals. • The GNS interlayer enhanced electrochemical activity of PbO 2 electrode. • The lifetime of GSN-PbO 2 electrode was 1.93 times that of PbO 2 electrode. • An electrochemical mineralization mechanism of 2-chlorophenol was proposed. - Abstract: A novel PbO 2 electrode with a graphene nanosheet interlayer (marked as GNS-PbO 2 ) was prepared combining electrophoretic deposition and electro-deposition technologies. The micro morphology, crystal structure and surface chemical states of GNS-PbO 2 electrodes were characterized using scanning electronic microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their electrochemical properties and stability were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ·OH radicals test and accelerated life test, and compared with traditional PbO 2 electrodes. Besides, their potential application in the electrochemical degradation of 2-chlorophenol (2-CP) was investigated. The GNS-PbO 2 electrode possessed perfect octahedral β-PbO 2 microcrystals, and its grain size was much smaller than that of traditional PbO 2 electrode. It exhibited higher electrochemical activity than traditional PbO 2 electrode due to its larger electrochemical active surface area and stronger ·OH radicals generation ability. The service lifetime of GNS-PbO 2 electrode (107.9 h) was 1.93 times longer than that of traditional PbO 2 electrode (55.9 h). The electrochemical degradation rate constant of 2-CP on GNS-PbO 2 electrode (k app = 2.75 × 10 −2 min −1 ) is much higher than for PbO 2 electrode (k app = 1.76 × 10 −2 min −1 ). 2-CP oxidation yielded intermediates including aromatic compounds (catechol, phenol and ortho-benzoquinone) and organic acids (oxalic acid, maleic acid and

Optimization of headspace experimental factors to determine chlorophenols in water by means of headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry and parallel factor analysis.

Science.gov (United States)

Morales, Rocío; Cruz Ortiz, M; Sarabia, Luis A

2012-11-19

In this work an analytical procedure based on headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry (HS-SPME-GC/MS) is proposed to determine chlorophenols with prior derivatization step to improve analyte volatility and therefore the decision limit (CCα). After optimization, the analytical procedure was applied to analyze river water samples. The following analytes are studied: 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TrCP), 2,3,4,6-tetrachlorophenol (2,4,6-TeCP) and pentachlorophenol (PCP). A D-optimal design is used to study the parameters affecting the HS-SPME process and the derivatization step. Four experimental factors at two levels and one factor at three levels were considered: (i) equilibrium/extraction temperature, (ii) extraction time, (iii) sample volume, (iv) agitation time and (v) equilibrium time. In addition two interactions between four of them were considered. The D-optimal design enables the reduction of the number of experiments from 48 to 18 while maintaining enough precision in the estimation of the effects. As every analysis took 1h, the design is blocked in 2 days. The second-order property of the PARAFAC (parallel factor analysis) decomposition avoids the need of fitting a new calibration model each time that the experimental conditions change. In consequence, the standardized loadings in the sample mode estimated by a PARAFAC decomposition are the response used in the design because they are proportional to the amount of analyte extracted. It has been found that block effect is significant and that 60°C equilibrium temperature together with 25min extraction time are necessary to achieve the best extraction for the chlorophenols analyzed. The other factors and interactions were not significant. After that, a calibration based in a PARAFAC2 decomposition provided the following values of CCα: 120, 208, 86, 39ngL(-1) for 2,4-DCP, 2,4,6-TrCP, 2,3,4,5-TeCP and PCP respectively for a

Parameter Identification of the 2-Chlorophenol Oxidation Model Using Improved Differential Search Algorithm

Directory of Open Access Journals (Sweden)

Guang-zhou Chen

2015-01-01

Full Text Available Parameter identification plays a crucial role for simulating and using model. This paper firstly carried out the sensitivity analysis of the 2-chlorophenol oxidation model in supercritical water using the Monte Carlo method. Then, to address the nonlinearity of the model, two improved differential search (DS algorithms were proposed to carry out the parameter identification of the model. One strategy is to adopt the Latin hypercube sampling method to replace the uniform distribution of initial population; the other is to combine DS with simplex method. The results of sensitivity analysis reveal the sensitivity and the degree of difficulty identified for every model parameter. Furthermore, the posteriori probability distribution of parameters and the collaborative relationship between any two parameters can be obtained. To verify the effectiveness of the improved algorithms, the optimization performance of improved DS in kinetic parameter estimation is studied and compared with that of the basic DS algorithm, differential evolution, artificial bee colony optimization, and quantum-behaved particle swarm optimization. And the experimental results demonstrate that the DS with the Latin hypercube sampling method does not present better performance, while the hybrid methods have the advantages of strong global search ability and local search ability and are more effective than the other algorithms.

Solid-phase extraction of chlorophenols in seawater using a magnetic ionic liquid molecularly imprinted polymer with incorporated silicon dioxide as a sorbent.

Science.gov (United States)

Ma, Wanwan; Row, Kyung Ho

2018-07-20

A type of magnetic ionic liquid based molecularly imprinted polymer coated on SiO 2 (Fe 3 O 4 @SiO 2 @IL-MIPs) was prepared with 1-vinyl-3-ethylimidazole ionic liquid as functional monomer, and 1,4-butane-3,3'-bis-1-ethylimidazole ionic liquid as cross linker, 4-Chlorophenol as template was successfully applied as a selective adsorbent for selective extraction of 5 chlorophenols in seawater samples by using the magnetic solid-phase extraction (MSPE) method. 11 types of Fe 3 O 4 @SiO 2 @IL-MIPs were synthesized and investigated for their different compositions of functional monomer (such as [C 2 min][Br], [C 2 min][BF 4 ], [C 2 min][PF 6 ], acrylamide, methacrylic acid and 4-vinyl pyridine) and cross-linker (such as [C 4 min 2 ][Br], [C 4 min 2 ][BF 4 ], [C 4 min 2 ][PF 6 ], divinylbenzene, and ethylene glycol dimethacrylate), respectively. The [C 2 min][BF 4 ] and [C 4 min 2 ][PF 6 ] based Fe 3 O 4 @SiO 2 @IL-MIP with the highest extraction efficiencies was applied to the optimization experiment of MSPE process (including extraction time, adsorbent mass and desorption solvents). Good linearity was obtained with correlation coefficients (R 2 ) over 0.9990 and the relative standard deviations for the intra-day and inter-day determination were less than 3.10% with the extraction recoveries ranged from 85.0% to 98.4%. The results indicated that the proposed Fe 3 O 4 @SiO 2 @IL-MIPs possesses great identification and adsorption properties, and could be used as a good sorbent for selective extraction of CPs in environment waters. Copyright © 2018 Elsevier B.V. All rights reserved.

Enhanced aerobic degradation of 4-chlorophenol with iron-nickel nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Shen, Wenjuan; Mu, Yi; Wang, Bingning; Ai, Zhihui, E-mail: jennifer.ai@mail.ccnu.edu.cn; Zhang, Lizhi

2017-01-30

Highlights: • Bimetallic iron-nickel nanoparticles possessed an enhanced performance on aerobic degradation of 4-CP. • Hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI. • Superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process. • The 4-CP degradation pathways were dependent on the generated superoxide radicals in the nZVIN/Air process. - Abstract: In this study, we demonstrate that the bimetallic iron-nickel nanoparticles (nZVIN) possessed an enhanced performance in comparison with nanoscale zero-valent iron (nZVI) on aerobic degradation of 4-chlorophenol (4-CP). The 4-CP degradation rate constant in the aerobic nZVIN process (nZVIN/Air) was 5 times that in the classic nZVI counterpart system (nZVI/Air). Both reactive oxygen species measurement and inhibition experimental results suggested that hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI, on contrast, superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process. High performance liquid chromatography and gas chromatography-mass spectrometer analysis indicated the intermediates of the nZVI/Air system were p-benzoquinone and hydroquinone, which were resulted from the bond cleavage between the chlorine and carbon atom in the benzene ring by hydroxyl radicals. However, the primary intermediates of 4-CP found in the nZVIN/Air system were phenol via the direct dechlorination by superoxide radicals, accompanying with the formation of chloride ions. On the base of experimental results, a superoxide radicals mediated enhancing mechanism was proposed for the aerobic degradation of 4-CP in the nZVIN/Air system. This study provides new insight into the role of bimetallic nickel on enhancing removal of organic pollutants with nZVI.

An adsorption diffusion model for removal of para-chlorophenol by activated carbon derived from bituminous coal

International Nuclear Information System (INIS)

Sze, M.F.F.; McKay, G.

2010-01-01

Batch adsorption experiments were carried out to study the adsorptive removal and diffusion mechanism of para-chlorophenol (p-CP) onto Calgon Filtrasorb 400 (F400) activated carbon. The external mass transfer resistance is negligible in the adsorption process carried out under different conditions in batch operation. Intraparticle diffusion model plots were used to correlate the batch p-CP adsorption data; three distinct linear sections were obtained for every batch operation. The textural properties of F400 activated carbon showed that it has a large portion of supermicropores, which is comparable to the size of the p-CP molecules. Due to the stronger interactions between p-CP molecules and F400 micropores, p-CP molecules predominantly diffused and occupied active sites in micropore region by hopping mechanism, and eventually followed by a slow filling of mesopores and micropores. This hypothesis is proven by the excellent agreement of the intraparticle diffusion model plots and the textural properties of F400 activated carbon. - Integration of intraparticle diffusion model plots and textural properties of F400 activated carbon explain the diffusion mechanism of p-CP into porous carbon.

Physical and biological parameters that determine the fate of p-chlorophenol in laboratory test systems

International Nuclear Information System (INIS)

Pritchard, P.H.; O'Neill, E.J.; Spain, C.M.; Ahearn, D.G.

1987-01-01

Shake-flask and microcosm studies were conducted to determine the fate of para-chlorophenol (p-CP) in water and sediment systems and the role of sediment and nonsediment surfaces in the biodegradation process. Biodegradation of p-CP in estuarine water samples in shake flasks was slow over incubation periods of 300 h. The addition of detrital sediment resulted in immediate and rapid degradation evidence by the production of 14 CO 2 from [ 14 C]p-CP. The addition of sterile sediment, glass beads, or sand resulted in approximately four to six times more CO 2 evolution than observed in the water alone. Densities of p-CP-degrading bacteria associated with the detrital sediment were 100 times greater than those enumerated in water. Bacteria in the water and associated with the sediment after preexposure of both water and sediment of p-CP demonstrated enhanced biodegradation. In some microcosms, p-CP was degraded completely in the top 1.0 cm of intact sediment beds. Sediment reworking activities by benthic invertebrates from one site were sufficient to mix p-CP deep into the sediment bed faster than biodegradation or molecular diffusion. p-CP was persistent at lower depths of the sediment, possibly a result of reduced oxygen conditions preventing aerobic biodegradation

Bioremediation of soils contaminated with polycyclic aromatic hydrocarbons, petroleum, pesticides, chlorophenols and heavy metals by composting: Applications, microbes and future research needs.

Science.gov (United States)

Chen, Ming; Xu, Piao; Zeng, Guangming; Yang, Chunping; Huang, Danlian; Zhang, Jiachao

2015-11-01

Increasing soil pollution problems have caused world-wide concerns. Large numbers of contaminants such as polycyclic aromatic hydrocarbons (PAHs), petroleum and related products, pesticides, chlorophenols and heavy metals enter the soil, posing a huge threat to human health and natural ecosystem. Chemical and physical technologies for soil remediation are either incompetent or too costly. Composting or compost addition can simultaneously increase soil organic matter content and soil fertility besides bioremediation, and thus is believed to be one of the most cost-effective methods for soil remediation. This paper reviews the application of composting/compost for soil bioremediation, and further provides a critical view on the effects of this technology on microbial aspects in contaminated soils. This review also discusses the future research needs for contaminated soils. Copyright © 2015 Elsevier Inc. All rights reserved.

Predicting adsorptive removal of chlorophenol from aqueous solution using artificial intelligence based modeling approaches.

Science.gov (United States)

Singh, Kunwar P; Gupta, Shikha; Ojha, Priyanka; Rai, Premanjali

2013-04-01

The research aims to develop artificial intelligence (AI)-based model to predict the adsorptive removal of 2-chlorophenol (CP) in aqueous solution by coconut shell carbon (CSC) using four operational variables (pH of solution, adsorbate concentration, temperature, and contact time), and to investigate their effects on the adsorption process. Accordingly, based on a factorial design, 640 batch experiments were conducted. Nonlinearities in experimental data were checked using Brock-Dechert-Scheimkman (BDS) statistics. Five nonlinear models were constructed to predict the adsorptive removal of CP in aqueous solution by CSC using four variables as input. Performances of the constructed models were evaluated and compared using statistical criteria. BDS statistics revealed strong nonlinearity in experimental data. Performance of all the models constructed here was satisfactory. Radial basis function network (RBFN) and multilayer perceptron network (MLPN) models performed better than generalized regression neural network, support vector machines, and gene expression programming models. Sensitivity analysis revealed that the contact time had highest effect on adsorption followed by the solution pH, temperature, and CP concentration. The study concluded that all the models constructed here were capable of capturing the nonlinearity in data. A better generalization and predictive performance of RBFN and MLPN models suggested that these can be used to predict the adsorption of CP in aqueous solution using CSC.

[Using Excess Activated Sludge Treated 4-Chlorophenol Contained Waste Water to Cultivate Chlorella vulgaris].

Science.gov (United States)

Wang, Lu; Chen, Xiu-rong; Yan, Long; He, Yi-xuan; Shi, Zhen-dong

2015-04-01

Using different rations of sludge extracts and supernate from 4-Chlorophenol (4-CP) simulated wastewater's excess sludge after centrifugation to cultivate the Chlorella vulgaris to achieve the goal of excess sludge utilization together with chlorella cultivating. The experiments were performed in 500 mL flasks with different rations of sludge extracts & BG-11 and supernate & BG-11 in a light growth chamber respectively. Number of algal cells, Chlorophyll, enzyme activity, oil and water total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), toxicity index were investigated. Result showed that the nutrition supplies and toxicity in the excess sludge were removed efficiently via Chlorella vulgaris, the removal rates of TN and TP were at least 40% and 90% respectively; After 10 days cultivation, the density growth of 50% sludge extracts was 20 times higher of the beginning while its chlorophyll content was lower than that of the blank group. Sludge extracts could promote the proliferation of algae, but were not conducive to the synthesis of chlorophyll. The quantity of SOD in per cell showed Chlorella vulgaris gave a positive response via stimulation from toxicant in sludge extracts and supernate. The best time for collecting chlorella vulgaris was the fifth day of cultivation, taking neutral oil accumulation as the evaluating indicator for its utilization combined with the removal of supplies and toxicity.

Photocatalytic activity of V doped ZnO nanoparticles thin films for the removal of 2- chlorophenol from the aquatic environment under natural sunlight exposure.

Science.gov (United States)

Salah, Numan; Hameed, A; Aslam, M; Babkair, Saeed S; Bahabri, F S

2016-07-15

Vanadium doped ZnO powders were used as precursors to deposit thin films of V(5+) incorporated ZnO nanoparticles on glass substrates by the pulsed laser deposition technique. The observed variations in Raman signals, visible region shift in the diffuse reflectance spectra along with a small shift in the (101) reflections of the X-ray diffraction (XRD) confirmed the insertion of V(5+) ions in ZnO lattice. No other additional reflection in the XRD results other than ZnO further endorsed the occupation of lattice positions by V entities rather than independent oxide formation. The asymmetric XPS peaks of Zn2p and V2p core levels confirmed the existence of both in the vicinity. The existence of minimal proportion of V(3+) along with V(5+) states varied the alteration of the oxidation states V in the synthetic route. The SEM images at various resolutions displayed the uniform distribution identical nanoparticles without the presence of additional phases in the deposited films. The SEM cross-section measurements revealed the uniform thickness of ∼90 nm of each film, whereas the surface studies of the films were performed by AFM. The as-synthesized films were tested for photocatalytic activity in sunlight illumination for the removal of 2-chlorophenol. The unique feature of the study was the estimation of the photocatalytic activity 20 ppm of 2-chlorophenol by exposing the low exposed area. The degradation of the substrate was measured by liquid phase UV-vis spectroscopy, whereas total organic carbon measurement revealed the mineralization of the substrate. The released Cl(-) ions were also measured by ion chromatography. The estimated flatband potentials and pHzpc values of the V doped materials, by Mott-Schottky analysis and zeta potential measurements respectively, were correlated with the photocatalytic activity. The kinetics of the photocatalytic degradation/mineralization process was estimated and results were correlated with the plausible mechanism. Copyright �

SILAR BiOI-Sensitized TiO2 Films for Visible-Light Photocatalytic Degradation of Rhodamine B and 4-Chlorophenol.

Science.gov (United States)

Odling, Gylen; Robertson, Neil

2017-04-05

BiOI nanoplates were deposited upon a film of TiO 2 nanoparticles derived from a commercial source using a simple room temperature sequential ionic layer adsorption and reaction (SILAR) method. X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopies have been used to confirm the crystal phase, chemical states of key elements and morphology of the BiOI nanoplate-TiO 2 composites. Using both valence band X-ray photoelectron spectroscopy and UV/Vis diffuse reflectance measurements the band structure of the composites is determined to be that of a type II heterojunction. Through initial screening of the photocatalytic activity of the SILAR-modified films it was determined that five SILAR cycles are optimal in the photocatalytic degradation of rhodamine B. The visible-light sensitisation effect of BiOI was then proven by examination of the photocatalytic degradation of the colourless organic pollutant 4-chlorophenol, showing a large enhancement over an equivalent TiO 2 film. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of operational factors on bioregeneration of binary phenol and 4-chlorophenol-loaded granular activated carbon using PVA-immobilized biomass cryogels.

Science.gov (United States)

Leong, Kwok-Yii; Adnan, Rohana; Lim, Poh-Eng; Ng, Si-Ling; Seng, Chye-Eng

2017-09-01

The effects of dry biomass density in cryogel beads, shaking speed and initial concentration ratio of phenol to 4-chlorophenol (4-CP) on the bioregeneration efficiencies of binary phenol and 4-CP-loaded granular activated carbon (GAC) for phenol and 4-CP, respectively, were investigated under the simultaneous adsorption and biodegradation approach. The results revealed higher bioregeneration efficiencies of binary-loaded GAC for phenol and 4-CP at higher dry biomass density but moderate shaking speed. The optimum dry biomass density in cryogel beads and shaking speed for use in bioregeneration were found to be 0.01 g/mL and 250 rpm, respectively. With respect to the initial phenol to 4-CP concentration ratio, the bioregeneration efficiencies were lower under increasing phenol and 4-CP initial concentrations, respectively, with the effect being more conspicuous under increasing 4-CP concentration. Higher bioregeneration efficiencies were achieved with the use of immobilized rather than suspended biomasses.

Natural Hematite and Siderite as Heterogeneous Catalysts for an Effective Degradation of 4-Chlorophenol via Photo-Fenton Process

Directory of Open Access Journals (Sweden)

Haithem Bel Hadjltaief

2018-06-01

Full Text Available This paper describes a simple and low-cost process for the degradation of 4-Chlorophenol (4-CP from aqueous solution, using natural Tunisian Hematite (M1 and Siderite (M2. Two natural samples were collected in the outcroppings of the Djerissa mining site (Kef district, northwestern Tunisia. Both Hematite and Siderite ferrous samples were characterized using several techniques, including X-Ray Diffraction (XRD, Nitrogen Physisorption (BET, Infrared Spectroscopy (FTIR, H2-Temperature Programmed Reduction (H2-TPR, Scanning Electronic Microscopy (SEM linked with Energy Dispersive X-ray (EDS and High-Resolution Transmission Electron Microscopy (HRTEM. Textural, structural and chemical characterization confirmed the presence of Hematite and Siderite phases with a high amount of iron on the both surface materials. Their activity was evaluated in the oxidation of 4-CP in aqueous medium under heterogeneous photo-Fenton process. Siderite exhibited higher photocatalytic oxidation activity than Hematite at pH 3. The experimental results also showed that 100% conversion of 4-CP and 54% TOC removal can be achieved using Siderite as catalyst. Negligible metal leaching and catalyst reutilization without any loss of activity point towards an excellent catalytic stability for both natural catalysts.

Enzymatic removal of phenol and p-chlorophenol in enzyme reactor: Horseradish peroxidase immobilized on magnetic beads

International Nuclear Information System (INIS)

Bayramoglu, Guelay; Arica, M. Yakup

2008-01-01

Horseradish peroxidase was immobilized on the magnetic poly(glycidylmethacrylate-co-methylmethacrylate) (poly(GMA-MMA)), via covalent bonding and used for the treatment of phenolic wastewater in continuous systems. For this purposes, horseradish peroxidase (HRP) was covalently immobilized onto magnetic poly(GMA-MMA) beds using glutaraldehyde (GA) as a coupling agent. The maximum HRP immobilization capacity of the magnetic poly(GMA-MMA)-GA beads was 3.35 mg g -1 . The immobilized HRP retained 79% of the activity of the free HRP used for immobilization. The immobilized HRP was used for the removal of phenol and p-chlorophenol via polymerization of dissolved phenols in the presence of hydrogen peroxide (H 2 O 2 ). The effect of pH and temperature on the phenol oxidation rate was investigated. The results were compared with the free HRP, which showed that the optimum pH value for the immobilized HRP is similar to that for the free HRP. The optimum pH value for free and immobilized HRP was observed at pH 7.0. The optimum temperature for phenols oxidation with immobilized HRP was between 25 and 35 deg. C and the immobilized HRP has more resistance to temperature inactivation than that of the free form. Finally, the immobilized HRP was operated in a magnetically stabilized fluidized bed reactor, and phenols were successfully removed in the enzyme reactor

Adsorption of 4-chlorophenol from aqueous solutions by xad-4 resin: Isotherm, kinetic, and thermodynamic analysis

International Nuclear Information System (INIS)

Bilgili, M. Sinan

2006-01-01

Removal of 4-chlorophenol (4-CP) from synthetic aqueous solutions through adsorption on Amberlite XAD-4 resin, a non-ionic macroreticular resins, under batch equilibrium experimental conditions at 298, 308 and 318 K was investigated. It is necessary to propose a suitable model to a better understanding on the mechanism of 4-CP adsorption. For this purpose, Langmiur, Freundlich, Toth, and Redlich-Peterson (RP) isotherm models were compared. The two and three parameters in the adopted adsorption isotherm models were determined by the help of MATLAB package program. It was determined that best fitted adsorption isotherm models were obtained to be in the order: Redlich-Peterson > Langmuir > Toth > Freundlich isotherms. The pseudo-second-order kinetic model provided the best correlation to the experimental results. Results of the intra-particle diffusion model show that the pore diffusion is not the only rate limiting step. The lower correlation of the data to the Bangham's equation also represents that the diffusion of the adsorbate into pores of the sorbent is not the only rate-controlling step. The thermodynamic constants of adsorption phenomena; ΔG o , ΔH o , and ΔS o were found as -4.17 (at 298 K) kJ/mol, -42.01 kJ/mol, and -0.127 kJ/(mol K), respectively. The results showed that adsorption of 4-CP on Amberlite XAD-4, a nonionic polymeric resin was exothermic and spontaneous

Y{sub 2}O{sub 3} modified TiO{sub 2} nanosheets enhanced the photocatalytic removal of 4-chlorophenol and Cr (VI) in sun light

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaona; Wu, Pei [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Liu, Min [State Grid Zhejiang Electric Power Research Institute, Hangzhou, Zhejiang 310007 (China); Lu, Dingze [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Ming, Junlan [State Grid Zhejiang Electric Power Research Institute, Hangzhou, Zhejiang 310007 (China); Li, Chunhe; Ding, Junqian; Yan, Qiuyang [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Fang, Pengfei, E-mail: fangpf@whu.edu.cn [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China)

2017-07-15

Highlights: • Y{sub 2}O{sub 3}@TNSswithsynergisticphotocatalyticactivitywerepreparedbyone-potmethod. • Y{sub 2}O{sub 3} loading resulted in the structure evolution of TNSs and content increment of Ti{sup 3+} ions. • Modification on TNSs led to an obvious red shift of the optical absorption edge. • Appropriate amount of Y{sub 2}O{sub 3} can effectively improve the separation efficiency of the h{sup +}/e{sup −} pairs. - Abstract: Y{sub 2}O{sub 3} modified TiO{sub 2} nanosheets (Y{sub 2}O{sub 3}@TNSs), capable of exhibiting sun light, were synthesized through one pot/hydrothermal method using Y (NO{sub 3}){sub 3} as precursor. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of the as-prepared samples. The Y{sub 2}O{sub 3}@TNSs, with thickness of approximately 3–4 nm, large surface area of 240–350 m{sup 2}/g, were full of Y{sub 2}O{sub 3} nanoparticles highly dispersed on the surface. The introduction of Y{sub 2}O{sub 3} influenced the crystallinity and the structure evolution of TNSs, besides, improved the light absorption ability. The surface photo-current and fluorescence spectral studies revealed that the photo-generated charge carrier separation efficiency could be improved by an appropriate modification. The degradation activity of this sun-light-induced photocatalytic has enhanced apparently on 4-Chlorophenol and K{sub 2}Cr{sub 2}O{sub 7} solution, the degradation efficiency of 4-Chlorophenol reached 5.69 times than that of P25, and the maximum TOC removal obtained after 120 min was 67.6%, indicating that most organic compounds were released from the solution. The enhancement in the photocatalytic activity was attributed to the synergetic effect of the Y{sub 2}O{sub 3} and TNSs, which led to a fast separation and slow recombination of photo-induced electron-hole pairs. Consequently, the high efficiency in the experiments showed a promising application of

Catalytic decomposition of hydrogen peroxide and 4-chlorophenol in the presence of modified activated carbons.

Science.gov (United States)

Huang, Hsu-Hui; Lu, Ming-Chun; Chen, Jong-Nan; Lee, Cheng-Te

2003-06-01

The objective of this research was to examine the heterogeneous catalytic decomposition of H(2)O(2) and 4-chlorophenol (4-CP) in the presence of activated carbons modified with chemical pretreatments. The decomposition of H(2)O(2) was suppressed significantly by the change of surface properties including the decreased pH(pzc) modified with oxidizing agent and the reduced active sites occupied by the adsorption of 4-CP. The apparent reaction rate of H(2)O(2) decomposition was dominated by the intrinsic reaction rates on the surface of activated carbon rather than the mass transfer rate of H(2)O(2) to the solid surface. By the detection of chloride ion in suspension, the reduction of 4-CP was not only attributed to the advanced adsorption but also the degradation of 4-CP. The catalytic activity toward 4-CP for the activated carbon followed the inverse sequence of the activity toward H(2)O(2), suggesting that acidic surface functional group could retard the H(2)O(2) loss and reduce the effect of surface scavenging resulting in the increase of the 4-CP degradation efficiency. Few effective radicals were expected to react with 4-CP for the strong effect of surface scavenging, which could explain why the degradation rate of 4-CP observed in this study was so slow and the dechlorination efficiency was independent of the 4-CP concentration in aqueous phase. Results show that the combination of H(2)O(2) and granular activated carbon (GAC) did increase the total removal of 4-CP than that by single GAC adsorption.

Iron oxyhydroxide nanorods with high electrochemical reactivity as a sensitive and rapid determination platform for 4-chlorophenol

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuanyuan [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Britton Chance Center for Biomedical Photonics at Wuhan, National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Cheng, Qin; Zheng, Meng [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Liu, Xin [Britton Chance Center for Biomedical Photonics at Wuhan, National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Material Chemistry of Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2016-04-15

Highlights: • Prepared FeOOH nanorods exhibited high reactivity toward the oxidation of 4-CP. • Response signals and detection sensitivity of 4-CP increased greatly by FeOOH. • Highly-sensitive and rapid determination platform was developed for 4-CP. • Practical application in water samples was studied, and the accuracy was good. - Abstract: Iron oxyhydroxide (FeOOH) nanorods were prepared through solvothermal reaction, and characterized using Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and scanning electron microscopy. Thereafter, the prepared FeOOH nanorods were used as sensing material to construct a novel detection platform for 4-chlorophenol (4-CP). The electrochemical behaviors of 4-CP were studied, and the oxidation peak currents increased greatly on the surface of FeOOH nanorods. The signal enhancement mechanism was studied for 4-CP, and it was found that the prepared FeOOH nanorods remarkably improved the electron transfer ability and surface adsorption efficiency of 4-CP. The influences of pH value, amount of FeOOH nanorods and accumulation time were examined. As a result, a highly-sensitive electrochemical method was developed for the rapid determination of 4-CP. The linear range was from 10 to 500 nM, and the detection limit was 3.2 nM. It was used in different water samples, and the results consisted with the values that obtained by high-performance liquid chromatography.

Determination of chlorophenols in honey samples using in-situ ionic liquid-dispersive liquid-liquid microextraction as a pretreatment method followed by high-performance liquid chromatography.

Science.gov (United States)

Fan, Chen; Li, Nai; Cao, Xueli

2015-05-01

In-situ ionic liquid-dispersive liquid-liquid microextraction (IL-DLLME) method was developed as a pretreatment method for the detection of six chlorophenols (CPs) in honey samples. The hydrophobic ionic liquid [C4MIM][NTf2], formed in-situ by the hydrophilic ionic liquid [C4MIM][BF4] and the ion exchange reagent LiNTf2 was used as the microextractant solvent of CPs from honey sample. Then the enriched analytes were back-extracted into 40 μL of 0.14 M NaOH solution and finally subjected to analysis by high-performance liquid chromatography. The method showed low limit of detection of CPs, 0.8-3.2 μg/L and high enrichment factor, 34-65 with the recoveries range from 91.60% to 114.33%. The method is simple, rapid, environmentally friendly and with high extraction efficiency. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

Inhibition of dehydrogenase activity in petroleum refinery wastewater bacteria by phenolic compounds

OpenAIRE

Gideon C. Okpokwasili; Christian Okechukwu Nweke

2010-01-01

The toxicity of phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol on Pseudomonas, Bacillus and Escherichia species isolated from petroleum refinery wastewater was assessed via inhibition of dehydrogenase enzyme activity. At low concentrations, 2-nitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol stimulated dehydrogenase activity and at sufficient concentrations, phenolic compounds inhibi...

A direct comparison amongst different technologies (aerobic granular sludge, SBR and MBR) for the treatment of wastewater contaminated by 4-chlorophenol

International Nuclear Information System (INIS)

Carucci, Alessandra; Milia, Stefano; Cappai, Giovanna; Muntoni, Aldo

2010-01-01

Environmental concern on chlorinated phenols is rising due to their extreme toxicity even at low concentrations and their persistency in water and soils. Since the high amount of published data often lacks in terms of uniformity, direct comparisons amongst different treatment technologies are very difficult, or even impossible. In this study, granular sludge developed in an acetate-fed Granular sludge Sequencing Batch Reactor (GSBR) was used for the aerobic degradation of low chlorinated 4-chlorophenol (4CP), with readily biodegradable sodium acetate (NaAc) as growth substrate. A conventional Sequencing Batch Reactor (SBR) and a Membrane BioReactor (MBR) were operated in parallel under the same 4CP influent concentrations and/or 4CP volumetric organic loading rates as the GSBR, in order to carry out a direct comparison in terms of 4CP removal efficiencies and specific removal rates, effluent quality, waste sludge production, system simplicity, land area requirement, start-up times, NaAc dosage as growth substrate and maximum applied 4CP volumetric organic loading rate. A decision matrix was built to define the best technology to suit different scenarios: the GSBR was proved to be the most suitable technology when system simplicity, low land area requirement and short start-up times were considered as critical parameters for decision making.

Degradation of aqueous phenol solutions by coaxial DBD reactor

Science.gov (United States)

Dojcinovic, B. P.; Manojlovic, D.; Roglic, G. M.; Obradovic, B. M.; Kuraica, M. M.; Puric, J.

2008-07-01

Solutions of 2-chlorophenol, 4-chlorophenol and 2,6-dichlorophenol in bidistilled and water from the river Danube were treated in plasma reactor. In this reactor, based on coaxial dielectric barrier discharge at atmospheric pressure, plasma is formed over a thin layer of treated water. After one pass through the reactor, starting chlorophenols concentration of 20 mg/l was diminished up to 95 %. Kinetics of the chlorophenols degradation was monitored by High Pressure Liquid Chromatography method (HPLC).

Degradation mechanisms of 4-chlorophenol in a novel gas-liquid hybrid discharge reactor by pulsed high voltage system with oxygen or nitrogen bubbling.

Science.gov (United States)

Zhang, Yi; Zhou, Minghua; Hao, Xiaolong; Lei, Lecheng

2007-03-01

The effect of gas bubbling on the removal efficiency of 4-chlorophenol (4-CP) in aqueous solution has been investigated using a novel pulsed high voltage gas-liquid hybrid discharge reactor, which generates gas-phase discharge above the water surface simultaneously with the spark discharge directly in the liquid. The time for 100% of 4-CP degradation in the case of oxygen bubbling (7 min) was much shorter than that in the case of nitrogen bubbling (25 min) as plenty of hydrogen peroxide and ozone formed in oxygen atmosphere enhanced the removal efficiency of 4-CP. Except for the main similar intermediates (4-chlorocatechol, hydroquinone and 1,4-benzoquinone) produced in the both cases of oxygen and nitrogen bubbling, special intermediates (5-chloro-3-nitropyrocatechol, 4-chloro-2-nitrophenol, nitrate and nitrite ions) were produced in nitrogen atmosphere. The reaction pathway of 4-CP in the case of oxygen bubbling was oxygen/ozone attack on the radical hydroxylated derivatives of 4-CP. However, in the case of nitrogen bubbling, hydroxylation was the main reaction pathway with effect of N atom on degradation of 4-CP.

Performance study of SOL&PID system for the degradation of Acid Red 26 and 4-Chlorophenol

International Nuclear Information System (INIS)

Zhu, Li; Cui, Lingyun; Huang, Qunwu; Wang, Yiping; Vivar, Marta; Jin, Yanchao; Sun, Yong; Cui, Yong; Fan, Jiangyang

2017-01-01

Highlights: • A new water purification system with solar and UV-LED powered by PV was proposed. • UV-LED was driven by PV directly without any transformation. • More than 92% of P_m generated by PV was used to drive UV-LED array. • Visible and near-infra light was converted to UV via PV and UV-LED. • The flowing water makes PV and LED work at lower temperature. - Abstract: To increase the photocatalytic reaction rate and make full use of electricity generated by photovoltaics (PV), a water purification system (SOL&PID) with solar and ultraviolet-light emitting diode (UV-LED) powered by a hybrid PV photocatalytic reactor was designed and tested in this paper. The SOL&PID system is based on Solar Water Purification and Renewable Electricity Generation system (SOLWAT). Photovoltaic and photocatalytic performances of SOL&PID system were evaluated in comparison with SOLWAT by the degradation of Acid Red 26 (AR 26) and 4-chlorophenol (4-CP) using suspended TiO_2. To assess the directly-coupled performance between PV and UV-LED array, the power consumption percentage of UV-LED array from the maximum output power of PV was analyzed. The results show an adequate coupling between the UV-LED array and the photovoltaics. More than 92% of the maximum output power generated by PV modules is used to drive the LED array. The photocatalytic reaction rate constants in SOL&PID system increase respectively 29–37% and 31–78% during AR 26 and 4-CP experiments, in comparison with SOLWAT system. Besides, the SOL&PID system achieved lower solar module temperature and lower UV-LED pin temperature than the reference systems by the addition of flow channel.

Fenton-like oxidation of 4-chlorophenol using H2O2 in situ generated by Zn-Fe-CNTs composite.

Science.gov (United States)

Liu, Yong; Fan, Qing; Liu, Yanlan; Wang, Jianlong

2018-05-15

In this paper, a zinc-iron-carbon nanotubes (Zn-Fe-CNTs) composite was prepared, characterized and used to develop a Fenton-like system of Zn-Fe-CNTs/O 2 for the degradation of 4-chlorophenol (4-CP), in which H 2 O 2 was generated in situ from zinc-carbon galvanic cells and oxygen in aqueous solution was activated by iron attached on the surface of CNTs to produce ·OH radicals for the oxidation of 4-CP. The experimental results showed that the particles of Zn and Fe in Zn-Fe-CNTs composite were adhered to the surface of CNTs, which accelerated the electron transfer process. The BET area of Zn-Fe-CNTs composite was 32.9 m 2 /g. The contents of Zn and Fe (% w) in the composite were 44.7% and 4.2%, respectively. The removal efficiency of 4-CP and TOC in Zn-Fe-CNTs/O 2 system was 90.8% and 52.9%, respectively, with the initial pH of 2.0, O 2 flow rate of 800 mL/min, Zn-Fe-CNTs dosage of 1.0 g/L, 4-CP concentration of 50 mg/L and reaction time of 20 min. Based on the analysis of the degradation intermediate products with LC-MS and IC, a possible degradation pathway of 4-CP in Zn-Fe-CNTs/O 2 system was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

The effect of different exposed facets on the photoelectrocatalytic degradation of o-chlorophenol using p-type Cu_2O crystals

International Nuclear Information System (INIS)

Sang, Wenjing; Zhang, Gong; Lan, Huachun; An, Xiaoqiang; Liu, Huijuan

2017-01-01

Although it is known that the efficacy of photoelectrocatalysts is enhanced by increasing the amount of high energy surface exposed, the development of a universal synthesis method with both superior activity and simplicity is needed for scalable applications. We herein controllably fabricated cuprous oxide (Cu_2O) micro crystals with different morphologies, evolving from cubes, cuboctahedra, truncated octahedra and finally to octahedra on indium tin oxide (ITO) glass substrates, by a facile electrochemical deposition method. The structures of facet-engineered Cu_2O samples and the underlying mechanism for the morphology evolution were investigated. The separation of photogenerated hole-electron pairs on Cu_2O crystals with different exposed facets was characterized by measuring the photocurrent densities with chopped illumination, which increased with the increased concentrations of PVP: the octahedral Cu_2O crystals, with the highest proportion of {111} facets exposed, exhibited the lowest electro-hole recombination in contrast to the cubes, cuboctahedra, and truncated octahedra, respectively. The photoelectrocatalytic degradation efficiency of the o-chlorophenol (2-CP) pollutant under sunlight irradiation with Cu_2O-coated photocathode was further investigated to reveal the effect of different exposed facets. Due to the increased number of surface active sites available for degradation reactions, the octahedral Cu_2O microcrystals presented higher photoelectrocatalytic activity compared to other shapes. Active oxygen species detected by electron spin-resonance (ESR) spectrometry implied that abundant superoxide radicals (O_2"●"−) were the dominant active radicals in the degradation.

Electrodeposition of palladium and reduced graphene oxide nanocomposites on foam-nickel electrode for electrocatalytic hydrodechlorination of 4-chlorophenol

International Nuclear Information System (INIS)

Liu, Yong; Liu, Lan; Shan, Jun; Zhang, Jingdong

2015-01-01

Highlights: • Pd and reduced graphene oxide are deposited on foam-Ni via electrodeposition. • Pd particles supported on RGO possess large active surface area. • Pd/RGO/foam-Ni shows high electrocatalytic activity for dechlorination of 4-CP. • 100% 4-CP can be removed on Pd/RGO/foam-Ni under optimum ECH conditions. - Abstract: A high-performance palladium (Pd) and reduced graphene oxide (RGO) composite electrode was prepared on foam-nickel (foam-Ni) via two-step electrodeposition processes. The scanning electron microscopic (SEM) observation showed that the obtained Pd/RGO/foam-Ni composite electrode displayed a uniform and compact morphology. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) analysis confirmed the successful deposition of Pd and RGO on nickel substrate. The cyclic voltammetric (CV) measurements indicated that the presence of RGO greatly enhanced the active surface area of Pd particles deposited on foam-Ni. The as-deposited Pd/RGO/foam-Ni electrode was applied to electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP). Various factors influencing the dechlorination of 4-CP such as dechlorination current, initial concentration of 4-CP, Na 2 SO 4 concentration and initial pH were systematically investigated. The thermodynamic analysis showed that the dechlorination reaction of 4-CP at different temperatures followed the first-order kinetics and the activation energy for 4-CP dechlorination on Pd/RGO/foam-Ni electrode was calculated to be 51.96 kJ mol −1 . Under the optimum conditions, the dechlorination efficiency of 4-CP could reach 100% after 60-min ECH treatment. Moreover, the prepared Pd/RGO/foam-Ni composite electrode showed good stability for recycling utilization in ECH of 4-CP

Determination of Phenols in Water Samples using a Supported ...

African Journals Online (AJOL)

The sample preparation method was tested for the determination of phenols in river water samples and landfill leachate. Concentrations of phenols in river water were found to be in the range 4.2 μg L–1 for 2-chlorophenol to 50 μg L–1 for 4-chlorophenol. In landfill leachate, 4-chlorophenol was detected at a concentration ...

Toxicity assessment of 4-chlorophenol to aerobic granular sludge and its interaction with extracellular polymeric substances

Energy Technology Data Exchange (ETDEWEB)

Wei, Dong; Wang, Yifan; Wang, Xiaodong; Li, Mengting; Han, Fei; Ju, Luyu; Zhang, Ge; Shi, Li; Li, Kai; Wang, Bingfeng [School of Resources and Environmental Sciences, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environmental Sciences, University of Jinan, Jinan 250022 (China); Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Wei, Qin [Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

2015-05-30

Highlights: • Toxicity of 4-CP to aerobic granular sludge process was evaluated. • 3D-EEM characterized the interaction between EPS and 4-CP. • Tryptophan was the main substance result in fluorescence quenching. • The mechanism of fluorescence quenching belongs to static quenching. - Abstract: The main objective of this study was to evaluate the toxicity of 4-chlorophenol (4-CP) to aerobic granular sludge in the process of treating ammonia rich wastewater. In the short-term exposure of 4-CP of 5 and 10 mg/L, ammonia nitrogen removal efficiencies in the batch reactors decreased to 87.18 ± 2.81 and 41.16 ± 3.55%, which were remarkably lower than that of control experiment (99.83 ± 0.54%). Correspondingly, the respirometric activities of heterotrophic and autotrophic bacteria of aerobic granular sludge were significantly inhibited in the presence of 4-CP. Moreover, the main components of extracellular polymeric substances (EPS) including polysaccharides and proteins increased from 18.74 ± 0.29 and 22.57 ± 0.34 mg/g SS to 27.79 ± 0.51 and 24.69 ± 0.38 mg/g SS, respectively, indicating that the presence of 4-CP played an important role on the EPS production. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy further showed that the intensities of EPS samples were obviously quenched with the increased of 4-CP concentrations. To be more detailed, synchronous fluorescence spectra indicated that the interaction between EPS and 4-CP was mainly caused by tryptophan residues. The mechanism of fluorescence quenching belongs to static quenching with a formation constant (K{sub A}) of 0.07 × 10{sup 4} L/mol, implying the strong formation of EPS and 4-CP complex. The results could provide reliable and accurate information to determine the potential toxicity of 4-CP on the performance of aerobic granular sludge system.

Hollow-fiber-supported liquid phase microextraction with in situ derivatization and gas chromatography-mass spectrometry for determination of chlorophenols in human urine samples.

Science.gov (United States)

Ito, Rie; Kawaguchi, Migaku; Honda, Hidehiro; Koganei, Youji; Okanouchi, Noriya; Sakui, Norihiro; Saito, Koichi; Nakazawa, Hiroyuki

2008-09-01

A simple and highly sensitive method that involves hollow-fiber-supported liquid phase microextraction (HF-LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) was developed for the determination of chlorophenols (CPs) such as 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TrCP), 2,3,4,6-tetrachlorophenol (TeCP) and pentachlorophenol (PCP) in human urine samples. Human urine samples were enzymatically de-conjugated with beta-glucuronidase and sulfatase. After de-conjugation, HF-LPME with in situ derivatization was performed. After extraction, 2 microl of extract was carefully withdrawn into a syringe and injected into the GC-MS system. The limits of detection (S/N=3) and quantification (S/N>10) of CPs in the human urine samples are 0.1-0.2 ng ml(-1) and 0.5-1 ng ml(-1), respectively. The calibration curve for CPs is linear with a correlation coefficient of >0.99 in the range of 0.5-500 ng ml(-1) for DCP and TrCP, and of 1-500 ng ml(-1) for TeCP and PCP, respectively. The average recoveries of CPs (n=6) in human urine samples are 81.0-104.0% (R.S.D.: 1.9-6.6%) with correction using added surrogate standards. When the proposed method was applied to human urine samples, CPs were detected at sub-ng ml(-1) level.

Preparation of three-dimensional mesoporous polymer in situ polymerization solid phase microextraction fiber and its application to the determination of seven chlorophenols.

Science.gov (United States)

Wang, Xuemei; Wang, Huan; Huang, Pengfei; Ma, Xiaomin; Lu, Xiaoquan; Du, Xinzhen

2017-01-06

A superior solid-phase microextraction (SPME) fiber-coating material, three dimensional order mesoporous polymers with Ia-3d bicontinuous cubic structure (3D-OMPs) was in situ coated on a stainless steel wire by solvent evaporation induced self-assembly (EISA) and thermo-polymerization. Fourier-transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), small-angel X-ray diffraction (SAXRD), N 2 adsorption-desorption transmission, and thermogravimetry analysis (TGA) were applied to the characterization of the synthesized 3D-OMPs coating. The performance and feasibility of the homemade fiber was evaluated through direct immersion (DI) SPME followed by high-performance liquid chromatography-UV detector (HPLC-UV) for the simultaneous extraction of seven chlorophenols in water samples. Under the optimum conditions, the prepared fiber exhibited excellent extraction properties as compared to three commercial fibers, the DI-SPME-HPLC-UV method showed low limits of detection (0.32-1.85μgL -1 ), wide linear ranges (5.0-1000μgL -1 ), and acceptable reproducibility (relative standard deviation, RSD<7.6% for one fiber, RSD<8.9% for fiber to fiber). Moreover, the method was further successfully applied to the analysis of seven CPs in real samples with good recoveries (80.5-99.5%) and satisfactory precisions (RSD<9.2%). It was confirmed that the proposed method has high sensitivity, outstanding selectivity and good reproducibility to the determination of trace CPs in the environmental water. Copyright © 2016 Elsevier B.V. All rights reserved.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxidation of 2,4,6,-tri-chlorophenol catalyzed by iron phthalocyanines covalently bound to silica. Oxydation du 2,4,6-trichlorophenol catalyse par des phtalocyanines de fer greffees sur silice par liaisons covalentes

Energy Technology Data Exchange (ETDEWEB)

Sanchez, M.; Hadasch, A.; Meunier, B. (Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France). Laboratoire de Chimie de Coordination); Rabion, A. (Elf-Atochem, 64 - Artix (France). Centre de Recherche)

1999-04-01

The degradation of recalcitrant pollutants remains a high priority in order to preserve our environment. For example, chlorinated aromatic compounds are extremely persistent in the environment because of their slow biodegradation by microorganisms. One of the most notable toxic offenders is 2,4,6-tri-chlorophenol (TCP) which is produced by paper mills and also used as a biocide. Thus TCP is an obvious benchmark for research on the decontamination of waste waters. In this work, the covalent attachment of an iron phthalocyanine with chloro-sulfonyl substituents (FePcSO[sub 2]Cl) onto a functionalized 3-amino-propyl-silica has been achieved. This supported catalyst FePcSO[sub 2]Cl-silica is able to degrade a recalcitrant pollutant like TCP with hydrogen peroxide as oxidant. In order to improve the catalytic efficiency of the grafted iron phthalocyanine complex, modifications of the macrocycle substituents, passivation of the silica surface, variation of the loading of the carrier and addition of an organic co solvent to the reaction mixture were carried out. (authors) 21 refs.

Adsorption of phenolic compound by aged-refuse

Energy Technology Data Exchange (ETDEWEB)

Chai Xiaoli [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)]. E-mail: xlchai@mail.tongji.edu.cn; Zhao Youcai [State Key Laboratory of Pollution Control and Resource Reuse, School of Enviromental Science and Engineering, Tongji University, Siping Road 1239, Shanghai 200092 (China)

2006-09-01

The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic.

Adsorption of phenolic compound by aged-refuse

International Nuclear Information System (INIS)

Chai Xiaoli; Zhao Youcai

2006-01-01

The adsorption of phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol by aged-refuse has been studied. Adsorption isotherms have been determined for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol and the data fits well to the Freundlich equation. The chlorinated phenols are absorbed more strongly than the phenol and the adsorption capacity has an oblivious relationship with the numbers and the position of chlorine subsistent. The experiment data suggests that both the partition function and the chemical adsorption involve in the adsorption process. Pseudo-first-order and pseudo-second-order model were applied to investigate the kinetics of the adsorption and the results show that it fit the pseudo-second-order model. More than one step involves in the adsorption process and the overall rate of the adsorption process appears to be controlled by the chemical reaction. The thermodynamic analysis indicates that the adsorption is spontaneous and endothermic

Determination of Phenols in Water Samples using a Supported ...

African Journals Online (AJOL)

NJD

in the range 4.2 µg L–1 for 2-chlorophenol to 50 µg L–1 for 4-chlorophenol. In landfill leachate ... industries.1 Phenols are also used as part of the raw materials in ... chemical detection.20 In all of the above cases of mem- brane-based ...

Visible-light photoactivity of plasmonic silver supported on mesoporous TiO2 nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

Science.gov (United States)

Jaafar, N. F.; Jalil, A. A.; Triwahyono, S.

2017-01-01

Various weight loadings of Ag (1-10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti3+ site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag0 and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag0, TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

Electrocatalytic Reduction-oxidation of Chlorinated Phenols using a Nanostructured Pd-Fe Modified Graphene Catalyst

International Nuclear Information System (INIS)

Shi, Qin; Wang, Hui; Liu, Shaolei; Pang, Lei; Bian, Zhaoyong

2015-01-01

A Pd-Fe modified graphene (Pd-Fe/G) catalyst was prepared by the Hummers oxidation method and bimetallic co-deposition method. The catalyst was then characterized by various characterization techniques and its electrochemical property toward the electrocatalytic reduction-oxidation of chlorinated phenols was investigated by using cyclic voltammetry and differential pulse voltammetry. The results of the characterization show that the Pd-Fe/G catalyst in which the weight proportion of Pd and Fe is 1:1 has an optimal surface performance. The diameter of the Pd-Fe particles is approximately 5.2 ± 0.3 nm, with a uniform distribution on the supporting graphene. This is smaller than the Pd particles of a Pd-modified graphene (Pd/G) catalyst. The Pd-Fe/G catalyst shows a higher electrocatalytic activity than the Pd/G catalyst for reductive dechlorination when feeding with hydrogen gas. The reductive peak potentials of −0.188 V, −0.836 V and −0.956 V in the DPV curves are attributed to the dechlorination of ortho-Cl, meta-Cl, and para-Cl in 2-chlorophenol, 3-chlorophenol and 4-chlorophenol, respectively. In accordance with an analysis of the frontier orbital theory, the order of ease of dechlorination with Pd-Fe/G catalyst is 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The Pd-Fe/G catalyst has a greater activity than the Pd/G catalyst in accelerating the two-electron reduction of O_2 to H_2O_2, which is attributed to the higher current of the reduction peak at approximately −0.40 V when feeding with oxygen gas. Therefore, the Pd-Fe/G catalyst exhibits a higher electrocatalytic activity than the Pd/G catalyst for the reductive dechlorination and acceleration of the two-electron reduction of O_2 to H_2O_2.

Synergistic photocatalysis of Cr(VI) reduction and 4-Chlorophenol degradation over hydroxylated α-Fe{sub 2}O{sub 3} under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Wang, Ji-Chao; Ren, Juan [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450002 (China); Yao, Hong-Chang, E-mail: yaohongchang@zzu.edu.cn [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450002 (China); Zhang, Lin; Wang, Jian-She; Zang, Shuang-Quan [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450002 (China); Han, Li-Feng [Henan Provincial Key Laboratory of Surface & Interface Science, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Li, Zhong-Jun, E-mail: lizhongjun@zzu.edu.cn [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450002 (China)

2016-07-05

Highlights: • The surface hydroxyl of Fe{sub 2}O{sub 3} influences on the Cr(VI) reduction activity. • The synergistic photocatalysis enhances degradation activity of Cr(VI) and 4-CP. • The Fe{sub 2}O{sub 3} catalyst exhibits good stability and degradation activity after 9 runs. - Abstract: A series of Fe{sub 2}O{sub 3} materials with hydroxyl are synthesized in different monohydric alcohol (C{sub 2} – C{sub 5}) solvents by solvothermal method and characterized by XRD, BET, XPS, TG and EA. The amount of hydroxyl is demonstrated to be emerged on the surface of the as-synthesized Fe{sub 2}O{sub 3} particles and their contents are determined to be from 7.99 to 3.74 wt%. The Cr(VI) reduction experiments show that the hydroxyl content of Fe{sub 2}O{sub 3} samples exacts great influence on the photocatalytic activity under visible light irradiation (λ > 400 nm) and that the Fe{sub 2}O{sub 3} sample synthesized in n-butyl alcohol exhibits the optimal photocatalytic activity. The synergistic photocatalysis for 4-Chlorophenol (4-CP) degradation and Cr(VI) reduction over above Fe{sub 2}O{sub 3} sample is further investigated. The photocatalytic ratio of Cr(VI) reduction are enhanced from 24.8% to 70.2% while that of 4-CP oxidation are increased from 13.5% to 47.8% after 1 h visible light irradiation. The Fe{sub 2}O{sub 3} sample keeps good degradation rates of mixed pollutants after 9 runs. The active oxygen intermediates O{sub 2}{sup −}·, ·OH and H{sub 2}O{sub 2} formed in the photoreaction process are discovered by ESR measurement and UV–vis test. The photocatalytic degradation mechanism is proposed accordingly.

Inhibition of dehydrogenase activity in petroleum refinery wastewater bacteria by phenolic compounds

Directory of Open Access Journals (Sweden)

Gideon C. Okpokwasili

2010-04-01

Full Text Available The toxicity of phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol on Pseudomonas, Bacillus and Escherichia species isolated from petroleum refinery wastewater was assessed via inhibition of dehydrogenase enzyme activity. At low concentrations, 2-nitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol stimulated dehydrogenase activity and at sufficient concentrations, phenolic compounds inhibited dehydrogenase activities. Generally, phenol is less toxic than substituted phenols. Estimations of the degree of inhibition/stimulation of dehydrogenase activities showed significant dose-dependent responses that are describable by logistic functions. The toxicity thresholds varied significantly (P < 0.05 among the bacterial strains and phenolic compounds. The median inhibitory concentrations (IC50s ranged from 4.118 ± 0.097 mg.L-1 for 4-nitrophenol against Pseudomonas sp. DAF1 to 1407.997 ± 7.091 mg.L-1 for phenol against Bacillus sp. DISK1. This study suggested that the organisms have moderate sensitivity to phenols and have the potential to be used as indicators for assessment of chemical toxicity. They could also be used as catalysts for degradation of phenols in effluents.

Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels; Kloorattujen orgaanisten yhdisteiden muodostuminen kierraetyspolttoaineiden leijukerrospoltossa

Energy Technology Data Exchange (ETDEWEB)

Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M. [VTT Energy, Jyvaeskylae (Finland)

1997-10-01

Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels

International Nuclear Information System (INIS)

Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M.

1997-01-01

Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

Column operation studies for the removal of dyes and phenols using a low cost adsorbent

International Nuclear Information System (INIS)

Gupta, V. K.; Suhas; Tyagi, I.

2016-01-01

Fertilizer plant waste carbon slurry has been investigated after some processing used as efficient adsorbent for the fast removal and rapid adsorption of dyes and phenols using columns. The results reveals that the adsorbent developed from carbon slurry is carbonaceous in nature and having appreciable surface area (380 m2/g) can remove dyes both cationic (meldola blue, methylene blue, chrysoidine G, crystal violet) as well as anionic (ethyl orange, metanil yellow, acid blue 113), and phenols (phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol) fruitfully from water. The column type continuous flow operations were used to obtain the breakthrough curves. The breakthrough capacity, exhaustion capacity and degree of column utilization were optimized and evaluated from the plots. The results obtained revealed that the degree of column utilization for dyes falls in range from 60 to 76% while for phenols was in the range 53-58%. The exhaustion capacities were quite high as compared to the breakthrough capacities and were found to be 217, 211, 104, 126, 233, 248, 267 mg/g for meldola blue, crystal violet, chrysoidine G, methylene blue, ethyl orange, metanil yellow, acid blue 113, respectively and 25.6, 72.2, 82.2 and 197.3 mg/g for phenol, 2-chlorophenol, 4- chlorophenol and 2,4-dichlorophenol, respectively.

Inhibitory concentrations of 2,4D and its possible intermediates in sulfate reducing biofilms

Energy Technology Data Exchange (ETDEWEB)

Garcia-Cruz, Ulises [Department of Biotechnology, Environmental Science and Technology, Universidad Autonoma Metropolitana-Iztapalapa, Ave. San Rafael Atlixco 186, Vicentina, 09340 D.F. (Mexico); Celis, Lourdes B. [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San Jose 2055, Lomas 4a. Seccion, 78216 San Luis Potosi, S.L.P. (Mexico); Poggi, Hector [Department of Biotechnology and Bioengineering, CINVESTAV, Av. Instituto Politecnico Nacional 2508, Col. San Pedro Zacatenco, 07360 D.F. (Mexico); Meraz, Monica, E-mail: meraz@xanum.uam.mx [Department of Biotechnology, Environmental Science and Technology, Universidad Autonoma Metropolitana-Iztapalapa, Ave. San Rafael Atlixco 186, Vicentina, 09340 D.F. (Mexico)

2010-07-15

Different concentrations of the herbicide 2,4-dichlorophenoxyacetic acid (2,4D) and its possible intermediates such as 2,4-dichlorophenol (2,4DCP), 4-chlorophenol (4CP), 2-chlorophenol (2CP) and phenol, were assayed to evaluate the inhibitory effect on sulfate and ethanol utilization in a sulfate reducing biofilm. Increasing concentrations of the chlorophenolic compounds showed an adverse effect on sulfate reduction rate and ethanol conversion to acetate, being the intermediate 2,4DCP most toxic than the herbicide. The monochlorophenol 4CP (600 ppm) caused the complete cessation of sulfate reduction and ethanol conversion. The ratio of the electron acceptor to the electron donor utilized as well as the sulfate utilization volumetric rates, diminished when chlorophenols and phenol concentrations were increased, pointing out to the inhibition of the respiratory process and electrons transfer. The difference found in the IC{sub 50} values obtained was due to the chemical structure complexity of the phenolic compounds, the number of chlorine atoms as much as the chlorine atom position in the phenol ring. The IC{sub 50} values (ppm) indicated that the acute inhibition on the biofilm was caused by 2,4DCP (17.4) followed by 2,4D (29.0), 2CP (99.8), 4CP (108.0) and phenol (143.8).

Synthesis and characterization of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} and the visible light photocatalytic oxidation of 4-chlorophenol

Energy Technology Data Exchange (ETDEWEB)

Cao Guangxiu [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China); Li Yaogang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Zhang Qinghong, E-mail: zhangqh@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Wang Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

2010-06-15

In this work, we investigated the synergetic effect of La and F on the visible light photocatalytic activity of TiO{sub 2} catalysts. La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} photocatalysts were prepared by a simple sol-gel process using tetrabutyl titanate (TBT), La(NO{sub 3}){sub 3} and NH{sub 4}F as precursors. XPS results revealed that La{sub 2}O{sub 3} accumulated on the surface of TiO{sub 2}, which enhanced the surface area of TiO{sub 2} and inhibited the recombination of electron-hole pairs. It also showed that two kinds of fluorine species were formed and these increased the acid active sites and enhanced the oxidation potential of the photogenerated holes in the valance band. UV-vis diffuse reflection spectra of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} showed that intraband gap states were present and these are probably responsible for its absorption of visible light while the intrinsic absorption band was shifted slightly to a longer wavelength. At molar ratios of La and F to Ti of 1.5:100 and 5:100 and after calcination at 500 deg. C, the degradation rate of 4-chlorophenol (4-CP) over the sample was about 1.2-3.0 times higher than that of the other doped samples and undoped TiO{sub 2}. The total organic carbon (TOC) removal rates of 4-CP showed that 4-CP was mineralized efficiently in the presence of the sample under visible light illumination.

Evaluación de un electrodo de carbón vítreo modificado con Zeolita tipo “A” en la adsorción de 2-clorofenol

Directory of Open Access Journals (Sweden)

Aurora Molina

2009-10-01

Full Text Available Glassy carbon electrodes modified with Zeolite “A” were studied in order to evidence the adsorption of 2-chlorophenol. Synthesis of zeolite was undertaken by a hydrothermal method using calcined kaolin as raw material. The zeolite was first exchanged with calcium ions. Then, it was modified with the cationic surfactant CTAB (cetyl trimethyl ammonium bromide or the non-ionic surfactant Triton X-100 (t-octylphenoxy-polyethoxyethanol. Adsorption of 2-chlorophenol was evaluated by cyclic voltammetry, once it was adsorbed onto the modified electrode. Electrochemical results indicated that the films surfactant-zeolites were able to adsorb the 2-chlorophenol from an aqueous alkaline medium. The best results were achieved when the cationic surfactant CTAB was used. The importance of electrode surface cleaning to guarantee the complete adherence between the vitreous carbon and the modified surfactant zeolite was determinated. Polishing and cleaning processes depend on the type of surfactant used.

Photocatalytic activity of porous multiwalled carbon nanotube-TiO{sub 2} composite layers for pollutant degradation

Energy Technology Data Exchange (ETDEWEB)

Zouzelka, Radek [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Department of Physical Chemistry, University of Chemistry and Technology Prague, 16628 Prague (Czech Republic); Kusumawati, Yuly [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France); Remzova, Monika [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Department of Physical Chemistry, University of Chemistry and Technology Prague, 16628 Prague (Czech Republic); Rathousky, Jiri [J. Heyrovsky Institute of Physical Chemistry, v.i.i., Academy of Sciences of the Czech Republic, Dolejskova 3, 18223 Prague 8 (Czech Republic); Pauporté, Thierry, E-mail: thierry.pauporte@chimie-paristech.fr [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue Pierre et Marie Curie, 75005 Paris (France)

2016-11-05

Highlights: • A simple method for TiO{sub 2}/graphene nanocomposite layer preparation. • Stable coatings on glass substrate. • Mesoporous nanocomposite films with high internal surface area. • High photoactivity for 4-chlorophenol degradation. • Analysis of photocatalysis enhancement mechanism. - Abstract: TiO{sub 2} nanoparticles are suitable building blocks nanostructures for the synthesis of porous functional thin films. Here we report the preparation of films using brookite, P25 titania and anatase pristine nanoparticles and of nanocomposite layers combining anatase nanoparticles and multi-walled carbon nanotube (MWCNT) at various concentrations. The structure and phase composition of the layers were characterized by X-ray diffraction and Raman spectroscopy. Their morphology and texture properties were determined by scanning electron microscopy and krypton adsorption experiments, respectively. Additionally to a strong absorption in the UV range, the composites exhibited light absorption in the visible range as well. The photocatalytic performance of the layers was tested in the degradation of aqueous solutions of 4-chlorophenol serving as a model of an eco-persistent pollutant. Besides the determination of the decrease in the concentration of 4-chlorophenol, also the formation of intermediate degradation products, namely hydroquinone and benzoquinone, was followed. The presence of MWCNTs had a beneficial effect on the photocatalytic performance, a marked increase in the photocatalytic degradation rate constant being observed even at very low concentrations of MWCNTs. Compared to a P25 reference layer, the first order rate reaction constant increased by about 100% for the composite films containing MWCNTs at concentrations above 0.6 wt%. The key parameters for the enhancement of the photocatalytic performance are discussed. The presence of carbon nanotubes influences beneficially the degradation of 4-chlorophenol by an attack of the primarily

Oxidative degradation of phenols in sono-Fenton-like systems upon high-frequency ultrasound irradiation

Science.gov (United States)

Aseev, D. G.; Sizykh, M. R.; Batoeva, A. A.

2017-12-01

The kinetics of oxidative degradation of phenol and chlorophenols upon acoustic cavitation in the megahertz range (1.7 MHz) is studied experimentally in model systems, and the involvement of in situ generated reactive oxygen species (ROSs) is demonstrated. The phenols subjected to high frequency ultrasound (HFUS) are ranked in terms of their rate of conversion: 2,4,6-trichlorophenol > 2,4-dichlorophenol 2-chlorophenol > 4-chlorophenol phenol. Oxidative degradation upon HFUS irradiation is most efficient at low concentrations of pollutants, due to the low steady-state concentrations of the in situ generated ROSs. A dramatic increase is observed in the efficiency of oxidation in several sonochemical oxidative systems (HFUS in combination with other chemical oxidative factors). The system with added Fe2+ (a sono-Fenton system) derives its efficiency from hydrogen peroxide generated in situ as a result of the recombination of OH radicals. The S2O8 2-/Fe2+/HFUS system has a synergetic effect on substrate oxidation that is attributed to a radical chain mechanism. In terms of the oxidation rates, degrees of conversion, and specific energy efficiencies of 4-chlorophenol oxidation based on the amount of oxidized substance per unit of expended energy the considered sonochemical oxidative systems form the series HFUS < S2O8 2-/HFUS < S2O8 2-/Fe2+/HFUS.

Fiscal 2000 survey report. Research on laser-aided photolysis of environmental pollutant in liquid phase system; 2000 nendo ekisokei ni okeru kankyo osen busshitsu no laser hikari bunkai gijutsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Experiments were conducted on laser-aided decomposition and removal of chemical substances in liquid phase systems on the assumption that there existed chemical pollutants in wastewater or water after washing burned ash. The aim of the research was to split carbon-chlorine bonds and break benzene rings, the two being the cause of harmfulness, and experiments were conducted using chlorophenol. The photolytic lasers were ArF excimer laser and KrF excimer laser. It was found that the reduction rate of chlorophenol in a water solution under excimer laser irradiation was 1.7 times higher under KrF laser than under ArF laser. For mediums other than water, isopropanol was used, more convenient than chlorophenol in separating organic pollutants from burned ash and the like. In this case, organochlorine compounds were generated at the beginning, but they disappeared when irradiation was prolonged. It was demonstrated that the laser-aided environmental cleaning technology would find a very wide scope of application as an effective photolytic means. (NEDO)

Removing 3,5-Dichlorophenol from Wastewater by Alternative Adsorbents

Directory of Open Access Journals (Sweden)

Kobetičová Hana

2014-12-01

Full Text Available The main objective of this paper is to evaluate an efficiency of 3,5 - dichlorophenol removal from wastewater by using alternative adsorbents. Chlorophenols are organic compounds consisting of a benzene ring, OH groups and also atoms of chlorine. Chlorophenols may have a huge isomere variety that means there are differences in their chemical and physical properties. Due to their toxicity it is necessary to remove them from waste water and in this paper an alternative way of such process is described.

Adsorption Isotherms of Phenol and 4-Chlorophenol on Petroleum Asphaltenes Adsorption du phénol et du 4-chlorophénol sur les asphaltènes pétroliers

Directory of Open Access Journals (Sweden)

Jaoui M.

2006-11-01

Full Text Available The adsorption isotherms for phenol and 4-chlorophenol from water onto asphaltenes flocculated in bulk and asphaltenes deposited on silica were established by frontal analysis chromatography at 293, 298, 303, and 308 K. The adsorption was more important with asphaltenes flocculated in bulk and corresponded to a Freundlich isotherm mechanism. The high adsorbed amount of phenols suggests possible migration of phenols through the loose asphaltene structure. Isotherms observed with the silica coated by asphaltenes showed that adsorption occurs in two stages corresponding probably to two different organizations of solute molecules at the surface. Les isothermes d'adsorption du phénol et du 4-chlorophénol en solution dans l'eau sur des asphaltènes floculés en masse et sur des asphaltènes déposés sur de la silice ont été déterminés par analyse chromatographique frontale à 293, 298, 303 et 308 K. L'adsorption sur des asphaltènes floculés en masse était la plus importante avec des isothermes correspondant à un mécanisme de Freundlich. La quantité élevée de phénols adsorbés suggère une migration possible des molécules du phénol à travers la structure peu compacte des asphaltènes. Les isothermes observés dans le cas de silice tapissée d'asphaltènes ont montré que l'adsorption se produit en deux étapes correspondant probablement à deux organisations différentes des molécules de soluté à la surface.

Visible-light photoactivity of plasmonic silver supported on mesoporous TiO2 nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

International Nuclear Information System (INIS)

Jaafar, N.F.; Jalil, A.A.; Triwahyono, S.

2017-01-01

Highlights: • Ag 0 loaded on MTN was prepared by a direct in-situ electrochemical method. • The introduction of Ag 0 lowers the band gap and increases the number of OV and TSD. • Ag 0 acted as an electrons trapper and also a plasmonic sensitizer. • The formation of Ti-O-Ag in 10 wt% Ag-MTN decreased the amount of Ag 0 , TSD and OV. • 5 wt% Ag-MTN gave the highest percentage of photodegradation of 2-CP. - Abstract: Various weight loadings of Ag (1–10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti 3+ site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag 0 and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag 0 , TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

Impact of phenolic substrate and growth temperature on the arthrobacter chlorophenolicus proteome

Energy Technology Data Exchange (ETDEWEB)

Unell, Maria; Abraham, Paul E.; Shah, Manesh; Zhang, Bing; Ruckert, Christian; VerBerkmoes, Nathan C.; Jansson, Janet K.

2009-02-15

We compared the Arthrobacter chlorophenolicus proteome during growth on 4-chlorophenol, 4-nitrophenol or phenol at 5 C and 28 C; both for the wild type and a mutant strain with mass spectrometry based proteomics. A label free workflow employing spectral counting identified 3749 proteins across all growth conditions, representing over 70% of the predicted genome and 739 of these proteins form the core proteome. Statistically significant differences were found in the proteomes of cells grown under different conditions including differentiation of hundreds of unknown proteins. The 4-chlorophenol-degradation pathway was confirmed, but not that for phenol.

Visible-light photoactivity of plasmonic silver supported on mesoporous TiO{sub 2} nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

Energy Technology Data Exchange (ETDEWEB)

Jaafar, N.F. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Jalil, A.A., E-mail: aishahaj@utm.my [Centre of Hydrogen Energy, Institute of Future Energy, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia); Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, UTM, 81310 Johor Bahru, Johor (Malaysia)

2017-01-15

Highlights: • Ag{sup 0} loaded on MTN was prepared by a direct in-situ electrochemical method. • The introduction of Ag{sup 0} lowers the band gap and increases the number of OV and TSD. • Ag{sup 0} acted as an electrons trapper and also a plasmonic sensitizer. • The formation of Ti-O-Ag in 10 wt% Ag-MTN decreased the amount of Ag{sup 0}, TSD and OV. • 5 wt% Ag-MTN gave the highest percentage of photodegradation of 2-CP. - Abstract: Various weight loadings of Ag (1–10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti{sup 3+} site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag{sup 0} and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag{sup 0}, TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

Role of iron species in the photo-transformation of phenol in artificial and natural seawater

International Nuclear Information System (INIS)

Calza, Paola; Massolino, Cristina; Pelizzetti, Ezio; Minero, Claudio

2012-01-01

The role played by iron oxides (goethite and akaganeite) and iron(II)/(III) species as photo-sensitizers toward the transformation of organic matter was examined in saline water using phenol as a model molecule. The study was carried out in NaCl 0.7 M solution at pH 8, artificial (ASW) and natural (NSW) seawater, in a device simulating solar light spectrum and intensity. Under illumination phenol decomposition occurs in all the investigated cases. Conversely, dark experiments show that no reaction takes place, implying that phenol transformation is a light- activated process. Following the addition of Fe(II) ions to aerated solutions, Fe(II) is easily oxidized to Fe(III) and hydrogen peroxide is formed. Regardless of the addition of Fe(II) or Fe(III) ions, photo-activated degradation is mediated by Fe(III) species. Several (and different) hydroxylated and halogenated intermediates were identified. In ASW, akaganeite promotes the formation of ortho and para chloro derivatives (2- and 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol), while goethite induces the formation of 3-chlorophenol and bromophenols. Conversely, Fe(II) or Fe(III) addition causes the formation of 3- and 4-chlorophenol and 2,3- or 3,4-dichlorophenol. 4-Bromophenol was only identified when irradiating Fe(II) spiked solutions. Natural seawater sampled in the Gulf of Trieste, Italy, has been spiked with phenol and irradiated. Phenol photo-induced transformation in NSW mediated by natural photosensitizers occurs and leads to the formation of numerous halophenols, condensed products and nitrophenols. When NSW is spiked with phenol and iron oxides, Fe(II) or Fe(III), halophenols production is enhanced. A close analogy exists between Fe(III), Fe(II)/goethite in ASW and NSW products. Different halophenols production in the natural seawater samples depends on Fe(II)/goethite (above all for 3-chlorophenol, 2,3-dichlorophenol and 4-bromophenol formation) and on Fe(III) colloidal species (3

Studies on (acid + base) equilibria in substituted (phenol + n-butylamine) systems in acetonitrile

Energy Technology Data Exchange (ETDEWEB)

Kozak, A. [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Czaja, M. [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Chmurzynski, L. [Department of General Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)]. E-mail: lech@chem.univ.gda.pl

2005-08-15

(Acid + base) equilibria, including molecular heteroconjugation ones, between n-butylamine and one of the following phenols: 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,5-dinitrophenol, 3-chlorophenol, 4-chlorophenol, 2,3,4,5,6-pentachlorophenol and 2,4,6-tribromophenol have been studied potentiometrically in a protophobic polar aprotic solvent, acetonitrile. Among the phenols studied, 2,5-dinitrophenol exhibited the strongest tendency towards formation of asymmetric hydrogen bonds with n-butylamine, whereas a weakest complex was formed with 2-nitrophenol. In the (n-butylamine + 2,3,4,5,6-pentachlorophenol) and (n-butylamine + 2,4-dinitrophenol) systems proton transfer reactions occurred.

Removal of 2,4-dichlorophenol and pentachlorophenol from waters by sorption using coal fly ash from a Portuguese thermal power plant

International Nuclear Information System (INIS)

Estevinho, Berta N.; Martins, Isabel; Ratola, Nuno; Alves, Arminda; Santos, Lucia

2007-01-01

Chlorophenols are one of the most important groups of priority pollutants, due to their high toxicity, mutagenicity and carcinogenicity. Although activated carbon has been the preferred choice for the removal of such pollutants from wastewaters, the search for cheaper alternative sorbents became common in the last years. Fly ash, a by-product from coal burning power plants, has a surface composition that may enable the sorption of specific organic compounds. Therefore, this feasibility study presents the optimization of the operating parameters of a fixed-bed column containing fly ash particles, percolated by aqueous solutions of 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) with concentrations of 1 and 100 μg/ml. Both chlorophenols were analysed by gas chromatography with electron capture detection (GC-ECD), after solid-phase microextraction (SPME), with limits of detection (LODs) of 7.28 μg/l for 2,4-DCP and 1.76 μg/l for PCP. Removal efficiencies above 99% were obtained for an initial concentration of 10 μg/ml of chlorophenols. Column saturation was achieved after 7 h of continuous operation for 2,4-DCP and 10 h for the PCP for feed levels of 10 μg/ml. Fly ash exhibited more affinity towards the sorption of PCP, in comparison to 2,4-DCP

Chlorination Revisited: Does Cl- Serve as a Catalyst in the Chlorination of Phenols?

Science.gov (United States)

Lau, Stephanie S; Abraham, Sonali M; Roberts, A Lynn

2016-12-20

The aqueous chlorination of (chloro)phenols is one of the best-studied reactions in the environmental literature. Previous researchers have attributed these reactions to two chlorine species: HOCl (at circum-neutral and high pH) and H 2 OCl + (at low pH). In this study, we seek to examine the roles that two largely overlooked chlorine species, Cl 2 and Cl 2 O, may play in the chlorination of (chloro)phenols. Solution pH, chloride concentration, and chlorine dose were systematically varied in order to assess the importance of different chlorine species as chlorinating agents. Our findings indicate that chlorination rates at pH pH 6.0 and a chlorine dose representative of drinking water treatment, Cl 2 O is predicted to have at best a minor impact on chlorination reactions, whereas Cl 2 may contribute more than 80% to the overall chlorination rate depending on the (chloro)phenol identity and chloride concentration. While it is not possible to preclude H 2 OCl + as a chlorinating agent, we were able to model our low-pH data by considering Cl 2 only. Even traces of chloride can generate sufficient Cl 2 to influence chlorination kinetics, highlighting the role of chloride as a catalyst in chlorination reactions.

Photocatalytic oxidation of organic compounds via waveguide-supported titanium dioxide films

Science.gov (United States)

Miller, Lawrence W.

A photochemical reactor based on titanium dioxide (TiO2)-coated silica optical fibers was constructed to explore the use of waveguide-supported TiO2 films for photocatalytic oxidation of organic compounds. The reactor was used for the photocatalytic oxidation of 4-chlorophenol in water. It was confirmed that TiO2 films could be securely attached to silica optical fibers. The 4-chlorophenol (100 mumol/L in water) was successfully oxidized on the TiO2 surface when UV light (310 nm--380 nm) was propagated through the fibers to the films. Rates of 4-chlorophenol oxidation and UV light flux to the fibers were measured. The quantum efficiency of 4-chlorophenol oxidation [defined as the change in 4-chlorophenol concentration divided by the UV light absorbed by the catalyst] was determined as a function of TiO2 catalyst film thickness and internal incident angle of propagating UV light. A maximum quantum efficiency of 2.8% was measured when TiO2 film thickness was ca. 80 nm and the maximum internal incident angle of propagating light was 84°. Quantum efficiency increased with increasing internal angle of incidence of propagating light and decreased with TiO2 film thickness. UV-Visible internal reflection spectroscopy was used to determine whether UV light propagated through TiO2-coated silica waveguides in an ATR mode. Propagation of UV light in an ATR mode was confirmed by the similarities between internal reflection spectra of phenolphthalein obtained with uncoated and TiO2-coated silica crystals. Planar silica waveguides coated with TiO2 were employed in a photocatalytic reactor for the oxidation of formic acid (833 mumol/L in water). It was shown that the quantum yield of formic acid oxidation [defined as the moles of formic acid oxidized divided by the moles of UV photons absorbed by the catalyst] on the waveguide-supported TiO2 surface is enhanced when UV light propagates through the waveguides in an ATR mode. A maximum quantum yield of 3.9% was found for formic

Formation of hydroxyl radicals and kinetic study of 2-chlorophenol photocatalytic oxidation using C-doped TiO2, N-doped TiO2, and C,N Co-doped TiO2 under visible light.

Science.gov (United States)

Ananpattarachai, Jirapat; Seraphin, Supapan; Kajitvichyanukul, Puangrat

2016-02-01

This work reports on synthesis, characterization, adsorption ability, formation rate of hydroxyl radicals (OH(•)), photocatalytic oxidation kinetics, and mineralization ability of C-doped titanium dioxide (TiO2), N-doped TiO2, and C,N co-doped TiO2 prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy were used to analyze the titania. The rate of formation of OH(•) for each type of titania was determined, and the OH-index was calculated. The kinetics of as-synthesized TiO2 catalysts in photocatalytic oxidation of 2-chlorophenol (2-CP) under visible light irradiation were evaluated. Results revealed that nitrogen was incorporated into the lattice of titania with the structure of O-Ti-N linkages in N-doped TiO2 and C,N co-doped TiO2. Carbon was joined to the Ti-O-C bond in the C-doped TiO2 and C,N co-doped TiO2. The 2-CP adsorption ability of C,N co-doped TiO2 and C-doped TiO2 originated from a layer composed of a complex carbonaceous mixture at the surface of TiO2. C,N co-doped TiO2 had highest formation rate of OH(•) and photocatalytic activity due to a synergistic effect of carbon and nitrogen co-doping. The order of photocatalytic activity per unit surface area was the same as that of the formation rate of OH(•) unit surface area in the following order: C,N co-doped TiO2 > C-doped TiO2 > N-doped TiO2 > undoped TiO2.

Degradation of di-, tri-, tetra-, and pentachlorophenol mixtures in an ...

African Journals Online (AJOL)

STORAGESEVER

2010-06-07

Jun 7, 2010 ... Chlorophenols are highly toxic xenobiotic compounds, normally found in the effluents of many industries. ... and paper, oil and petrochemical, synthetic plastics, ... organisms (Bettman and Rehm, 1985; Zache and. Rehm ...

NCBI nr-aa BLAST: CBRC-MLUC-01-0100 [SEVENS

Lifescience Database Archive (English)

Full Text Available CBRC-MLUC-01-0100 ref|YP_002487505.1| translation initiation factor IF-2 [Arthrobacter chlorophenolic... translation initiation factor IF-2 [Arthrobacter chlorophenolicus A6] YP_002487505.1 3e-04 28% ...

MECHANISTIC RELATIONSHIPS AMONG PCDDS/FS, PCNS, PAHS, CLPHS, AND CLBZS IN MUNICIPAL WASTE INCINERATION

Science.gov (United States)

An extensive investigation was done to understand polychlorinated dibenzo-p-dioxin and furan (PCDD/F) formation mechanisms and their relationship with other organic compounds. PCDD/F, chlorophenols, chlorobenzenes, polyaromatic hydrocarbons and polychlorinated naphthalenes were ...

Molecular analysis of halorespiration in Desulfitobacterium spp. : catalysis and transcriptional regulation

NARCIS (Netherlands)

Gabor, K.

2006-01-01

Keywords: iron-sulphur proteins, protein-DNA interaction, allosteric regulation, redox regulation, gene redundancy, chlorophenols, bioremediationSoil and ground water contamination by halogenated organic compounds mainly used as biocides in agriculture or solvents and

Single sheet iron oxides

DEFF Research Database (Denmark)

Yin, Zhou

profile with reversible reduction and oxidation, suggesting the formation of FeII-OH/O-FeIII clusters as that in GRs were formed on the ITO electrode (trichloroethylene (TCE), tetrachloride (CT) and 4-chlorophenol are used to test...

Biomass characteristics in three sequencing batch reactors treating a wastewater containing synthetic organic chemicals

DEFF Research Database (Denmark)

Hu, Z.Q.; Ferraina, R.A.; Ericson, J.F.

2005-01-01

in all reactors. In contrast, effluent 3-nitrobenzoate was recorded when its influent concentration was increased to 5 mg L-1 and dropped only to below 1 mg L-1 after 300 days of operation. The competent (active) biomass fractions for these compounds were between 0.04% and 5.52% of the total biomass...... characteristics in the aerobic SBR and SBBR. While all reactors had very good COD removal (> 90%) and displayed nitrification, substantial nitrogen removal (74%) was only achieved in the anoxic/aerobic SBR. During the entire operational period, benzoate, theophylline and 4-chlorophenol were completely removed...... inferred from substrate-specific microbial enumerations. The measured competent biomass fractions for 4-chlorophenol and 3-nitrobenzoate degradation were significantly lower than the influent COD fractions of these compounds. Correspondent to the highest competent biomass fraction for benzoate degradation...

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

Energy Technology Data Exchange (ETDEWEB)

Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

International Nuclear Information System (INIS)

Yang Ji; Cao Limei; Guo Rui; Jia Jinping

2010-01-01

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m 2 g -1 , the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

Molecular characterization of anaerobic dehalogenation by Desulfitobacterium dehalogenans

NARCIS (Netherlands)

Smidt, H.

2001-01-01

Haloorganics such as chlorophenols and chlorinated ethenes are among the most abundant pollutants in soil, sediments and groundwater, mainly caused by past and present industrial and agricultural activities. Due to bioaccumulation and toxicity, these compounds threaten the integrity of the

Evaluation of Activated Carbon from Fluted Pumpkin Stem Waste for ...

African Journals Online (AJOL)

Michael Horsfall

ortho-phosphoric acid and used to adsorb phenol and chlorophenol in fixed bed micro column It was found ... Experimental data for ..... effects on some anti- nutritional factors and in vitro ... Sorption kinetic study on the removal of basic blue -9.

p-chlorophenol anchored onto zirconium tungstate

Indian Academy of Sciences (India)

Unknown

framework host materials with organic guests (Ozin 1992) and thin film .... DT-30 thermal analyser at a heating rate of 10°C min 1. ..... for particular metal ions enables it to act as an efficient ... Dines M B and Digiacomo P M 1981 Inorg. Chem.

Manganese zinc ferrite nanoparticles as efficient catalysts for wet ...

Indian Academy of Sciences (India)

ing 4-chlorophenol as the model compound. A series of ... 8M/Na3 where, N is Avogadro number and M is molec- ular weight of ... using PHILIPS Model CM 200 Transmission Electron .... cles are formed from integer multiples of primary par-.

Removal efficiency and economic cost comparison of hydrated electron-mediated reductive pathways for treatment of bromate

DEFF Research Database (Denmark)

Nawaz, Shah; Shah, Noor S.; Khan, Javed Ali

2017-01-01

Bromate, a potential carcinogen, is a well known highly persistent and environmentally recalcitrant contaminant. UV-254/sulfite-based advanced reductive pathways (ARPs) were proposed to eliminate bromate successfully from water. Experiments with N2, N2O, 2-chlorophenol, inorganic ions, and differ...

Xenobiotic organic compounds in wastewater

DEFF Research Database (Denmark)

Eriksson, Eva; Baun, Anders; Henze, Mogens

2002-01-01

hundred of XOCs, among them mainly originating from hygiene products: chlorophenols, detergents and phthalates. Several compounds not deriving from hygiene products were also identified e.g. flame-retardants and drugs. A environmental hazard identification showed that a large number of compounds with high...

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

Science.gov (United States)

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

The differences in phenolic content in rivers exposed and non-exposed to anthropogenic contamination.

Science.gov (United States)

Michałowicz, Jaromir; Bukowska, Bozena; Duda, Wirgiliusz

2008-03-01

The purpose of the work was to determine the differences in a kind, number and concentrations of phenol, chlorophenols, chlorocatechols chlorinated methoxyphenols (chloroguaiacols, chlorosyringols) and 3,4,5-trichloroveratrole in the drainage of the Dzierzazna river, the flow non-exposed to anthropogenic contamination and in the Ner river, the flow exposed to anthropogenic pollution. The samples of water were collected in the Dzierzazna river in the Swoboda locality, the inflow of the Dzierzazna river - the Ciosenka river and, also, in the spring situated in Ciosny Sady locality. Water of the Ner river was collected in points near Łódź, Konstantynów, Poddebice and Dabie towns. The compounds were condensed (adsorbed) and eluted with methylene chloride on octadecyl C18 layer in a Baker Separex system. The obtained eluent was separated using the method of gas chromatography and analysed using mass spectrometry technique. In samples collected from the drainage of the Dzierzazna river phenol, chlorophenols, guaiacol, trichloroguaiacol, tetrachloroguaiacol, trichlorosyringol and 3,4,5-trichloroveratole were determined. As no anthropogenic sources are situated within the drainage of the Dzierzazna river, we may suppose that most of the determined compounds are mainly of natural origin. No or trace concentrations of chlorinated methoxyphenols were noted in the water of the Ner river, but a higher number, and concentrations of chlorophenols and additionally chlorocatechols were determined in this flow. It is also apparent that changes in a number and concentrations of phenols in the water of the Ner river did not prove a seasonal character, which was typical of the Dzierzazna drainage waters.

Synthesis of C-Doped TiO2 Nanoparticles by Novel Sol-Gel Polycondensation of Resorcinol with Formaldehyde for Visible-Light Photocatalysis

Czech Academy of Sciences Publication Activity Database

Neti, R.N.; Misra, R.; Bera, P.K.; Dhodapkar, R.; Bakardjieva, Snejana; Bastl, Zdeněk

2010-01-01

Roč. 40, č. 5 (2010), s. 328-332 ISSN 1553-3174 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z40400503 Keywords : C-doping * chlorophenol * photo activity * titanium dioxide Subject RIV: CA - Inorganic Chemistry Impact factor: 0.504, year: 2010

Assessment of an on-line CI-mass spectrometer as a continuous emission monitor for sewage sludge incinerators

International Nuclear Information System (INIS)

Campbell, K.R.; Hallett, D.J.; Resch, R.J.; Villinger, J.; Federer, V.

1991-01-01

ELI Eco Technologies Inc. tested two sewage sludge incinerators using regulator methods and a V and F CIMS-500 chemical ionization mass spectrometer. Correlations between dioxins and dibenzofurans from the regulatory MM5 trains and the continuous readings form the CIMS-500 for chlorobenzenes and chlorophenols were noted. As well, correlations between chlorinated organics and other volatile organics were obvious under poor combustion conditions. ELI Eco Technologies Inc. recently completed an extensive survey of organic chemical emissions including VOCs, chlorobenzenes, chlorophenols, chlorinated dioxins and dibenzofurans from two sewage sludge incinerators. The program was funded by the Municipality of Metro Toronto, Environment Ontario, and Environment Canada. Contaminants were measured by regulatory methods (ASME Modified Method 5) and simultaneously with the continuous mass spectrometer. The purpose of the study was to provide regulatory testing and at the same time evaluate the usefulness of the CIMS-500 mass spectrometer in assessing emissions. This paper describes the evaluation of the usefulness of this mass spectrometer

Performance Evaluation of AOP/Biological Hybrid System for Treatment of Recalcitrant Organic Compounds

Directory of Open Access Journals (Sweden)

Stanford S. Makgato

2010-01-01

Full Text Available Process water from nuclear fuel recovery unit operations contains a variety of toxic organic compounds. The use of decontamination reagents such as CCl4 together with phenolic tar results in wastewater with a high content of chlorophenols. In this study, the extent of dehalogenation of toxic aromatic compounds was evaluated using a photolytic advanced oxidation process (AOP followed by biodegradation in the second stage. A hard-to-degrade toxic pollutant, 4-chlorophenol (4-CP, was used to represent a variety of recalcitrant aromatic pollutants in effluent from the nuclear industry. A UV-assisted AOP/bioreactor system demonstrated a great potential in treatment of nuclear process wastewater and this was indicated by high removal efficiency (>98% under various 4-CP concentrations. Adding hydrogen peroxide (H2O2 as a liquid catalyst further improved biodegradation rate but the effect was limited by the scavenging of OH• radicals under high concentrations of H2O2.

The removal of chlorinated organic herbicide in water by gamma-irradiation

International Nuclear Information System (INIS)

Dilek Solpan; Murat Torun

2012-01-01

In this study, the radiation-induced degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide in aqueous solution was studied under various conditions as a function of irradiation dose in the absence and presence of hydrogen peroxide. The obtained data confirmed that largest yield of radiolytic degradation is obtained in oxidation processes/ionizing radiation, where oxidation is carried out with hydroxyl radicals. For complete degradation of 50 ppm 2,4-D, a required dose was lower in the presence of hydrogen peroxide. The formed major toxic phenolic intermediates were 2,4-dichlorophenol (2,4-DCP) and 4-chlorophenol (4-CP). The chemical analysis of the 2,4-D and the intermediates resulted from the radiolytic degradation were performed using a gas chromatography associated to mass spectrometry (GC-MS) with ion trap detector (ITD) and ion chromatography (IC). The formation of chlorophenols in addition to chloride, formaldehyde and carboxylic acids was studied as a function of absorbed dose. (author)

Inhibition of β-galactosidase and α-glucosidase synthesis in petroleum refinery effluent bacteria by phenolic compounds

Directory of Open Access Journals (Sweden)

Gideon C. Okpokwasili

2011-04-01

Full Text Available Inhibition of α-glucosidase (EC 3.2.1.20 and β-galactosidase (EC 3.2.1.23 biosynthesis by phenolic compounds (phenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol in Escherichia coli, Bacillus and Pseudomonas species isolated from petroleum refinery wastewater was assessed. At sufficient concentrations, phenols inhibited the induction of α-glucosidase and β-galactosidase. The patterns of these toxic effects can be mathematically described with logistic and sigmoid dose-response models. The median inhibitory concentrations (IC50 varied among the phenols, the bacteria and enzymes. Quantitative structure–activity relationship (QSAR models based on the logarithm of the octanol–water partition coefficient (log10Kow were developed for each bacterium. The correlation coefficients varied between 0.84and 0.99 for the enzymes. The test results indicated α-glucosidase and β-galactosidase biosynthesis as important microbial indices for evaluation of toxicity of phenolic compounds.

Graphene and graphene oxide modified by deep eutectic solvents and ionic liquids supported on silica as adsorbents for solid-phase extraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaoqin; Li, Guizhen; Row, Kyung Ho [Dept. of Chemistry and Chemical Engineering, Inha University, Incheon (Korea, Republic of)

2017-02-15

A novel deep eutectic solvent (DES) and ionic liquid (IL)-modified graphene (G) and graphene oxide (GO) were synthesized and used as effective adsorbents for the preconcentration of three chlorophenols (CPs), 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP), in environmental water samples prior to high-performance liquid chromatography (HPLC). The new materials were characterized by scanning electron microscopy (S-4200) and Fourier-transform infrared spectrometry. The prepared functionalized GO@silica shows remarkable adsorption capacity toward CPs. When used as solid-phase extraction (SPE) sorbents, a superior recovery (88.49–89.70%) could be obtained compared to commercial sorbents, such as silica and aminosilica. Based on this, a method for the analysis of CPs in water samples was established by coupling SPE with HPLC. These results highlight the potential new role of DES and IL-modified GO in the preparation of analytical samples.

Biodegradation of 2,4-dichlorophenol originating from ...

African Journals Online (AJOL)

STORAGESEVER

2009-06-03

Jun 3, 2009 ... of high concentration of chlorophenols. Appl. Microbiol. Biotechnol. 59: 599-604. Louie TM, Webster CM, Xun L (2002). Genetic and biochemical characterization of a 2,4,6- trichlorophenol degradation pathway in. Ralstonia eutropha JMP 134. J. Bacteriol. 184: 3492-3500. Lysetska M, Knoll A, Boehringer D ...

Purification of peroxidase from Horseradish (Armoracia rusticana) roots.

Science.gov (United States)

Lavery, Christopher B; Macinnis, Morgan C; Macdonald, M Jason; Williams, Joanna Bassey; Spencer, Colin A; Burke, Alicia A; Irwin, David J G; D'Cunha, Godwin B

2010-08-11

Peroxidase (EC 1.11.1.7) from horseradish ( Armoracia rusticana ) roots was purified using a simple, rapid, three-step procedure: ultrasonication, ammonium sulfate salt precipitation, and hydrophobic interaction chromatography on phenyl Sepharose CL-4B. The preparation gave an overall yield of 71%, 291-fold purification, and a high specific activity of 772 U mg(-1) protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified enzyme was homogeneous and had a molecular weight of approximately 40 kDa. The isolated enzyme had an isoelectric point of 8.8 and a Reinheitszahl value of 3.39 and was stable when stored in the presence of glycerol at -20 degrees C, with >95% retention of original enzyme activity for at least 6 months. Maximal activity of purified horseradish peroxidase (HRP) was obtained under different optimized conditions: substrate (guaiacol and H(2)O(2)) concentrations (0.5 and 0.3 mM, respectively), type of buffer (50 mM phosphate buffer), pH (7.0), time (1.0 min), and temperature of incubation (30 degrees C). In addition, the effect of HRP and H(2)O(2) in a neutral-buffered aqueous solution for the oxidation of phenol and 2-chlorophenol substrates was also studied. Different conditions including concentrations of phenol/2-chlorophenol, H(2)O(2), and enzyme, time, pH, and temperature were standardized for the maximal activity of HRP with these substrates; under these optimal conditions 89.6 and 91.4% oxidations of phenol and 2-chlorophenol were obtained, respectively. The data generated from this work could have direct implications in studies on the commercial production of this biotechnologically important enzyme and its stability in different media.

Determination of phenols by flow injection and liquid chromatography with on-line quinine-sensitized photo-oxidation and quenched luminol chemiluminescence detection

International Nuclear Information System (INIS)

Zhang Wei; Danielson, Neil D.

2003-01-01

An on-line quinine-sensitized photo-oxidation with quenched chemiluminescence (CL) detection method is developed for phenols using flow injection (FI) and liquid chromatography (LC). This detection method is based on the decrease of light emission from the luminol CL reaction due to the photo-oxidation of phenols that scavenge the photogenerated reactive oxygen species (e.g. singlet oxygen ( 1 O 2 ) and superoxide (O 2 · - )). On-line photo-oxidation is achieved using a coil photo-reactor made from fluoroethylene-propylene copolymer tubing (3048 mmx0.25 mm i.d.) coiled around a mercury UV lamp. A buffer of pH 7 and a concentration of 350 μM for quinine sulfate are determined optimum for the sensitized photo-oxidation. Using a carrier system flow rate of 60 μl/min, calibration curves taken by FI for 10 phenolic compounds in aqueous solutions showed this decreasing sensitivity order: 4-chlorophenol, phenol, 4-nitrophenol, 3-hydroxy-L-kynurenine, 2-nitrophenol, salicylate, 3-nitrophenol, catechol, 2,4-dinitrophenol, and 2,4-dichlorophenol. This detection method using two tandem coil photo-reactors is also applied for the LC separation of phenol, 4-nitrophenol and 4-chlorophenol on an octadecyl (C18) silica LC column using acetonitrile-H 2 O (40:60, v/v) as a mobile phase. The quenched CL detection limits (about 1 μM or 20 pmol) for phenol and 4-chlorophenol are comparable to those for UV detection at 254 nm. Some selectivity in the quenched CL detection is evident by no interference in the FI phenol response even when benzaldehyde and phenethanol concentrations are 8 and 15 times that of phenol

Formation of halogenated C-, N-DBPs from chlor(am)ination and UV irradiation of tyrosine in drinking water

International Nuclear Information System (INIS)

Chu Wenhai; Gao Naiyun; Krasner, Stuart W.; Templeton, Michael R.; Yin Daqiang

2012-01-01

The formation of regulated and emerging halogenated carbonaceous (C-) and nitrogenous disinfection by-products (N-DBPs) from the chlor(am)ination and UV irradiation of tyrosine (Tyr) was investigated. Increased chlorine contact time and/or Cl 2 /Tyr ratio increased the formation of most C-DBPs, with the exception of 4-chlorophenol, dichloroacetonitrile, and dichloroacetamideChloroform and dichloroacetic acid increased with increasing pH, dichloroacetonitrile first increased and then decreased, and other DBPs had maximum yields at pH 7 or 8. The addition of ammonia significantly reduced the formation of most C-DBPs but increased 4-chlorophenol, dichloroacetonitrile, dichloroacetamide, and trichloroacetonitrile yields for short prechlorination contact times before dosing ammonia. When UV irradiation and chlorination were performed simultaneously, the concentrations of the relatively stable C-DBPs increased, and the concentrations of dichloroacetonitrile, dichloroacetamide, and 4-chlorophenol decreased with increasing UV dose. This information was used to develop a mechanistic model for the formation of intermediate DBPs and end products from the interaction of disinfectants with tyrosine. Highlights: ► Increased contact time and/or Cl 2 /Tyr decreased the formation of some N-DBPs. ► Changing the pH of disinfection decreases the formation of some N-DBPs. ► N-DBP yields increased for short prechlorination contact time before dosing ammonia. ► Low pressure UV before chlorination did not impact the formation of DBPs from Tyr. ► A novel integrated formation pathway of halogenated C-, N-DBPs is proposed. - Exploring the integrated formation mechanism of regulated and emerging highly toxic DBPs, which is expected to preferably reduce their occurrence in drinking water.

Microreactor as Efficient Tool for Light Induced Oxidation Reactions

Czech Academy of Sciences Publication Activity Database

Hejda, S.; Drhová, Magdalena; Křišťál, Jiří; Buzek, D.; Krystyník, Pavel; Klusoň, Petr

2014-01-01

Roč. 255, NOV 1 (2014), s. 178-184 ISSN 1385-8947 Grant - others:GA MŠMT(CZ) MŠk:CZ.1.07/2.2.00/28.0205 Institutional support: RVO:67985858 Keywords : photo microreactor * phthalocyanine * chlorophenol oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 4.321, year: 2014

[Branch-specific detection of phenols and assessment of ground water solubility].

Science.gov (United States)

Fischer, F; Kerndorff, H; Kühn, S

2000-01-01

There are about 500 technically relevant phenolic compounds such as cresols, chlorophenols or nitrophenols. It is most preferable to determine phenols as single compounds via gas chromatography. Further, phenols can also be assayed as photometrically as an overall parameter (Phenolindex): however, no conclusions about specific compounds can be drawn from this type of test. Also this method is not as reliable for an hazard assessment as gas chromatography. First, not all phenols, for instance resorcinol or 1-naphthol can be determined with this method. Second, phenolic groups in humic substances, which do not constitute a threat for groundwater, are determined alongside environmentally relevant phenols using this method. In most cases, it is possible to deduce which phenols can be expected in the groundwater of contaminated sites from the type of industrial usage, such as chlorophenols and pulp bleaching or nitrophenols and the production of explosives. Phenols are formed during coal combustion for instance at cokemanufactures or gasworks. They are important raw materials for the chemical industry from which resins, surfactants, pharmaceuticals, pigments, explosives, and stabilizers are produced. During the 80's phenol, cresols, nonylphenols, anisidines, aminophenols, dihydroxybenzenes, and naphthols were manufactured in amounts exceeding 10,000 t/a. Also, phenolic compounds are used as additives in many areas for example as solvents in the electric industry, in sawmills, papermanufacture, electroplating of metal sheets, as photographic developers, as textile dyes, or for the tanning of hydes. Due to the formation and use of phenols at industrial sites, groundwater contaminations are possible via infiltration through the unsaturated zone. Especially at gasworks and ammunition factories, groundwater contaminations with phenols have become known. In the vicinity of railway tracks and associated facillities contaminations due to the use of pesticides or mineral oils

Photocatalytic activity of porous multiwalled carbon nanotube-TiO2 composite layers for pollutant degradation

Czech Academy of Sciences Publication Activity Database

Žouželka, Radek; Kusumawati, Y.; Remzová, Monika; Rathouský, Jiří; Pauporté, T.

2016-01-01

Roč. 317, MAY 2016 (2016), s. 52-59 ISSN 0304-3894 R&D Projects: GA MŠk LM2015073; GA MŠk(CZ) 7AMB14FR048 Institutional support: RVO:61388955 Keywords : TiO2 * carbon nanotubes * 4-chlorophenol Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 6.065, year: 2016

Mycoremediation of wood and soil from an old sawmill area contaminated for decades

Energy Technology Data Exchange (ETDEWEB)

Valentín, Lara; Oesch-Kuisma, Hanna; Steffen, Kari T.; Kähkönen, Mika A.; Hatakka, Annele; Tuomela, Marja, E-mail: marja.tuomela@helsinki.fi

2013-09-15

Highlights: • We performed experiments with non-sterile soil and wood with aged contamination. • We isolated fungal strains from a saw mill site with chlorophenols contamination. •Fungal strains were screened for tolerance to native microbes and contamination. • The best fungi degraded chlorophenols and chlorinated dibenzo-p-dioxins and -furans. -- Abstract: We investigated the potential of white-rot and litter-decomposing fungi for the treatment of soil and wood from a sawmill area contaminated with aged chlorinated phenols, dibenzo-p-dioxins and furans (PCDD/F). Eight screening assays with emphasis on application of non-sterile conditions were carried out in order to select the strains with capability to withstand indigenous microbes and contamination. Nine fungi were then selected for degrading pentachlorophenol (PCP), and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and mineralizing radiolabelled pentachlorophenol ({sup 14}C-PCP) in non-sterile soil or wood during 15 weeks of incubation. Soil indigenous microbes and fungal inoculated soil (fungal inoculum + indigenous microbes) achieved similar degradation of PCP and 2,3,4,6-TeCP and mineralization of {sup 14}C-PCP. However, the mineralization rate of {sup 14}C-PCP by indigenous microbes was much slower than that boosted by fungal inoculum. The litter-decomposing fungus (LDF) Stropharia rugosoannulata proved to be a suitable fungus for soil treatment. This fungus mineralized 26% of {sup 14}C-PCP and degraded 43% of 2,3,4,6-TeCP and 73% of PCP. Furthermore, S. rugosoannulata attained 13% degradation of PCDD/F (expressed as WHO-Toxic Equivalent). In wood, white-rot fungi grew and degraded chlorophenols better than LDF. No efficient indigenous degraders were present in wood. Interestingly, production of toxic chlorinated organic metabolites (anisoles and veratroles) by LDF in wood was negligible.

Mycoremediation of wood and soil from an old sawmill area contaminated for decades

International Nuclear Information System (INIS)

Valentín, Lara; Oesch-Kuisma, Hanna; Steffen, Kari T.; Kähkönen, Mika A.; Hatakka, Annele; Tuomela, Marja

2013-01-01

Highlights: • We performed experiments with non-sterile soil and wood with aged contamination. • We isolated fungal strains from a saw mill site with chlorophenols contamination. •Fungal strains were screened for tolerance to native microbes and contamination. • The best fungi degraded chlorophenols and chlorinated dibenzo-p-dioxins and -furans. -- Abstract: We investigated the potential of white-rot and litter-decomposing fungi for the treatment of soil and wood from a sawmill area contaminated with aged chlorinated phenols, dibenzo-p-dioxins and furans (PCDD/F). Eight screening assays with emphasis on application of non-sterile conditions were carried out in order to select the strains with capability to withstand indigenous microbes and contamination. Nine fungi were then selected for degrading pentachlorophenol (PCP), and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and mineralizing radiolabelled pentachlorophenol ( 14 C-PCP) in non-sterile soil or wood during 15 weeks of incubation. Soil indigenous microbes and fungal inoculated soil (fungal inoculum + indigenous microbes) achieved similar degradation of PCP and 2,3,4,6-TeCP and mineralization of 14 C-PCP. However, the mineralization rate of 14 C-PCP by indigenous microbes was much slower than that boosted by fungal inoculum. The litter-decomposing fungus (LDF) Stropharia rugosoannulata proved to be a suitable fungus for soil treatment. This fungus mineralized 26% of 14 C-PCP and degraded 43% of 2,3,4,6-TeCP and 73% of PCP. Furthermore, S. rugosoannulata attained 13% degradation of PCDD/F (expressed as WHO-Toxic Equivalent). In wood, white-rot fungi grew and degraded chlorophenols better than LDF. No efficient indigenous degraders were present in wood. Interestingly, production of toxic chlorinated organic metabolites (anisoles and veratroles) by LDF in wood was negligible

Environmentally Friendly Phthalocyanine Catalysts for Water Decontamination - Non Photocatalytic Systems

Czech Academy of Sciences Publication Activity Database

Klusoň, Petr; Drobek, M.; Zsigmond, A.; Baranyi, J.; Bata, P.; Zárubová, Š.; Kalaji, A.

2009-01-01

Roč. 91, 3-4 (2009), s. 605-609 ISSN 0926-3373 R&D Projects: GA ČR GD203/03/H140; GA AV ČR KAN400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : phthalocyanines * phenol * chlorophenols Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 5.252, year: 2009

Determination of Uptake and Release of 2,4-Dichlorophenol on the ...

African Journals Online (AJOL)

The uptake and release of 2,4-dichlorophenol on Nigerian clay soil was studied by introducing varying concentrations of the chlorophenol in 0.01 M aqueous calcium chloride solution at pH 4.5 into pretreated clay (0.6% OM) samples. The clay soil was treated with hydrogen peroxide followed by varying concentrations of ...

Dechlorination Ability of Municipal Waste Incineration Fly Ash for Polychlorinated Phenols

Czech Academy of Sciences Publication Activity Database

Vlková, Leona; Pekárek, Vladimír; Pacáková, V.; Karban, Jindřich; Bureš, M.; Štulík, K.

2004-01-01

Roč. 56, č. 10 (2004), s. 935-942 ISSN 0045-6535 R&D Projects: GA AV ČR IAA4072206; GA MŠk 1P04OE156 Institutional research plan: CEZ:AV0Z4072921 Keywords : chlorophenols * de novo synthesis * fly ash Subject RIV: CC - Organic Chemistry Impact factor: 2.359, year: 2004

Purification of a new isoform of laccase from a Marasmius quercophilus strain isolated from a cork oak litter (Quercus suber L).

Science.gov (United States)

Farnet, A M; Criquet, S; Pocachard, E; Gil, G; Ferre, E

2002-01-01

A new isoform of laccase from Marasmius quercophilus is described in this study. The strain of this white-rot fungus was isolated for the first time on a cork oak litter. This isoform exhibited certain common properties of laccases (a molecular weight of 65 Kda, an optimum pH of 6.2 with syringaldazine). But this laccase has also particularly novel features: the best activity measured was observed at high temperatures (80 C) and this isoform was not inhibited with EDTA. Furthermore, this induced laccase was able to transform most of the aromatic compounds tested without the addition of mediators to the reaction mixture, and the transformation of certain chlorophenols (2-chlorophenol and 2,4-dichlorophenol) by a laccase isoform from M. quercophilus is reported here for the first time. We also demonstrate the importance of 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) as a mediator since it allowed veratryl alcohol and p-hydroxybenzoic acid transformation. Moreover, new products of transformation were observed using the combination of ABTS with this isoform of laccase.

Metabolism of 2,4-dichlorophenol in tobacco engineered with bacterial degradative genes

International Nuclear Information System (INIS)

Perkins, E.J.; Sekine, M.; Gordon, M.P.

1990-01-01

The potential use of plants in toxic waste remediation has been overlooked. While chlorophenols are relatively slowly metabolized in Nicotiana tabacum var. Xanthi leaf extracts, chlorocatechols are rapidly metabolized, presumably by polyphenol oxidases. Our initial focus has been the fate of 2,4-dichlorophenol (2,4DCP) in var. Xanthi plants which express a bacterial 2,4DCP hydroxylase, which converts 2,4DCP to 3,5-dichlorocatechol. The roots of wild type and 2,4DCP hydroxylase transgenic plants growing in hydroponics were exposed to 14 C-2,4DCP. Approximately 95% of 14 C-2,4DCP metabolites remained in the roots when exposed to 2,4DCP. Upon extraction of root tissue, three major metabolites were found in untransformed plants and four major metabolites in transformed plants. Upon digestion with beta-D-glucosidase, these metabolites disappeared concomitant with the appearance of free 2,4DCP in wild type plants and 2,4DCP and 3,5-dichlorocatechol in transgenic plants. It is apparent that the chlorophenols are not readily available substrates for polyphenol oxidases in whole plants

Preparation of activated carbons from unburnt coal in bottom ash with KOH activation for liquid-phase adsorption.

Science.gov (United States)

Wu, Feng-Chin; Wu, Pin-Hsueh; Tseng, Ru-Ling; Juang, Ruey-Shin

2010-05-01

In this work, unburnt coal (UC) in bottom ash from coal-fired power plants was soaked in KOH solution and activated for 1 h at 780 degrees C. The yield of activated carbons varied from 47.8 to 54.8% when the KOH/UC weight ratio changed from 2 to 4. Pore properties of these activated carbons including the BET surface area, pore volume, pore size distribution, and pore diameter were characterized based on N(2) adsorption isotherms. It was shown that the isotherms for the adsorption of methylene blue, acid blue 74, and 4-chlorophenol from aqueous solutions on these activated carbons at 30 degrees C were well fitted by the Langmuir equation (correlation coefficient r(2) > 0.9968). The adsorption capacities of methylene blue, acid blue 74, and 4-chlorophenol were obtained to be 2.40-2.88, 0.57-1.29, and 2.34-5.62 mmol/g, respectively. Moreover, the adsorption kinetics could be suitably described by the Elovich equation. Copyright 2010. Published by Elsevier Ltd.

Process monitored spectrophotometric titration coupled with chemometrics for simultaneous determination of mixtures of weak acids.

Science.gov (United States)

Liao, Lifu; Yang, Jing; Yuan, Jintao

2007-05-15

A new spectrophotometric titration method coupled with chemometrics for the simultaneous determination of mixtures of weak acids has been developed. In this method, the titrant is a mixture of sodium hydroxide and an acid-base indicator, and the indicator is used to monitor the titration process. In a process of titration, both the added volume of titrant and the solution acidity at each titration point can be obtained simultaneously from an absorption spectrum by least square algorithm, and then the concentration of each component in the mixture can be obtained from the titration curves by principal component regression. The method only needs the information of absorbance spectra to obtain the analytical results, and is free of volumetric measurements. The analyses are independent of titration end point and do not need the accurate values of dissociation constants of the indicator and the acids. The method has been applied to the simultaneous determination of the mixtures of benzoic acid and salicylic acid, and the mixtures of phenol, o-chlorophenol and p-chlorophenol with satisfactory results.

Sulphonated Phthalocyanines as Effective Oxidation Photocatalysts

Czech Academy of Sciences Publication Activity Database

Klusoň, P.; Drobek, M.; Strašák, Tomáš; Krýsa, J.; Karásková, M.; Rakušak, J.

2008-01-01

Roč. 272, 1-2 (2008), s. 213-219 ISSN 1381-1169 R&D Projects: GA ČR(CZ) GD203/03/H140; GA AV ČR(CZ) KAN400720701 Institutional research plan: CEZ:AV0Z40720504 Keywords : phthalocyanines * 4-Chlorophenol * photocatalysis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.814, year: 2008

Molecular structure effects in photodegradation of phenol and its chlorinated derivatives with phthalocyanines

Czech Academy of Sciences Publication Activity Database

Klusoň, P.; Drobek, M.; Krejčíková, S.; Krýsa, J.; Kalaji, A.; Cajthaml, Tomáš; Rakušan, J.

2008-01-01

Roč. 80, 3-4 (2008), s. 321-326 ISSN 0926-3373 R&D Projects: GA AV ČR KAN400720701 Grant - others:CZ(CZ) GD203/03/H140; Mšk(CZ) IM4531433201 Program:GD Institutional research plan: CEZ:AV0Z50200510 Keywords : phthalocyanines * phenol * chlorophenols Subject RIV: EE - Microbiology, Virology Impact factor: 4.853, year: 2008

Degradation of di-, tri-, tetra-, and pentachlorophenol mixtures in an ...

African Journals Online (AJOL)

It is shown that the system is capable of treating up to 600 mgL-1 of total chlorophenols with excellent reduction values, and biodegradation rates (BDRs) between 87 - 97%, and 34 - 157 mgL-1 day-1, respectively (total organic carbon, TOC degradations up to 80%). In the case of the 800 mgL-1, a strong inhibition due to the ...

Electro oxidation of Phenol on a Ti/RuO{sub 2} anode: effect of some electrolysis parameters

Energy Technology Data Exchange (ETDEWEB)

Santos, Iranildes D. dos; Dutra, Achilles J.B. [Universidade Federal do Rio de Janeiro (PEMM/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Engenharia Metalurgica e de Materiais; Afonso, Julio C., E-mail: julio@iq.ufrj.b [Universidade Federal do Rio de Janeiro (IQ/UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Analitica

2011-07-01

The influences of electrolysis time, anodic area, current density and supporting electrolyte on phenol and its byproducts degradation on a Ti/RuO{sub 2} anode were investigated. It was observed that phenol and its byproducts were rapidly broken down in the presence of chloride ions. Gas chromatography/mass spectrometry (GC/MS) data have shown that the presence of chloride ions lead to chlorophenols formation, due to reactions with Cl{sub 2} and/or OCl{sup -} generated during electrolysis. However, these intermediate products were also degraded later by the oxidizing agents. The standards established by the CONAMA (Brazilian National Council for the Environment) for phenols and chlorophenols in effluents were achieved after 360 min of electrolysis with a current density of 10 mA cm-2. Cyclic voltammograms obtained with the anodes before and after 436 h of electrolysis under severe salinity conditions (2 mol L-1) and current density (800 mA cm-2) showed that Ti/RuO{sub 2} did not lose its electrocatalytic properties. This fact indicates that Ti/RuO{sub 2} can be used for the treatment of effluents containing phenols in a chloride environment. (author)

Synthesis and Characterization of Molecularly Imprinted Polymer Membrane for the Removal of 2,4-Dinitrophenol

Directory of Open Access Journals (Sweden)

Md. Jelas Haron

2013-02-01

Full Text Available Molecularly imprinted polymers (MIPs were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA and polystyrene (PS after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP and the PS membrane with MIP (PS-MIP was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo–second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol.

Preparation of graphene oxide-wrapped carbon sphere@silver spheres for high performance chlorinated phenols sensor

Energy Technology Data Exchange (ETDEWEB)

Gan, Tian, E-mail: gantsjy@163.com [College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000 (China); State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Lv, Zhen; Sun, Junyong; Shi, Zhaoxia; Liu, Yanming [College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000 (China)

2016-01-25

Highlights: • Hierarchical CS@Ag@GO composite was obtained by a simple solution route. • Signal amplification is achieved for sensitive detection of chlorinated phenols. • The low-cost method exhibits wide concentration range and acceptable accuracy. • The method can be successfully applied to detect chlorinated phenols in waters. - Abstract: A template-activated strategy was developed to construct core/shell structured carbon sphere@silver composite based on one-pot hydrothermal treatment. The CS@Ag possessed a uniform three-dimensional interconnected microstructure with an enlarged surface area and catalytic activity, which was further mechanically protected by graphene oxide (GO) nanolayers to fabricate intriguing configuration, which was beneficial for efficiently preventing the aggregation and oxidation of AgNPs and improving the electrical conductivity through intimate contact. By immobilizing this special material on electrode surface, the CS@Ag@GO was further used for sensitive determination of chlorinated phenols including 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol. The tailored structure, fast electron transfer ability and facile preparation of CS@Ag@GO made it a promising electrode material for practical applications in phenols sensing.

Ordered mesoporous carbon coating on cordierite: Synthesis and application as an efficient adsorbent

Energy Technology Data Exchange (ETDEWEB)

Wan, Ying, E-mail: ywan@shnu.edu.cn [Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234 (China); Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Cui, Xiangting; Wen, Zhentao [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China)

2011-12-30

Highlight: Black-Right-Pointing-Pointer Surfactant self-assembly of ordered mesoporous carbon coating on honeycomb cordierite. Black-Right-Pointing-Pointer Carbon coating with opened, hexagonally ordered pore arrays. Black-Right-Pointing-Pointer Honeycomb adsorbents for removal of p-chlorophenol. Black-Right-Pointing-Pointer The adsorbents exhibit large processing volume, and great advantages in reusability. - Abstract: Ordered mesoporous carbon coating on the honeycomb cordierite substrate has been prepared using low-polymerized phenolic resins as carbon sources and triblock copolymer F127 as the structure directing agent via the evaporation induced self-assembly route. The high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), and nitrogen sorption techniques prove the hexagonally ordered pore arrays of carbon coating on the cordierite. The honeycomb monolith adsorbents coated by ordered mesoporous carbons are directly used without any activation, and exhibit adsorption capacities for chlorinated organic pollutants in water with 200 mg/g for p-chlorophenol and 178 mg/g for p-chloroaniline (with respect to the net carbon coating), high adsorption ratio for low-concentration pollutants, large processing volumes and reusability. More than 200 repeated times can be achieved without obvious loss in both adsorption capacity and weight.

Synthetic Chemicals with Potential for Natural Attenuation (Postprint)

Science.gov (United States)

2012-07-01

The purpose of this paper is to describe examples of other synthetic organic compounds that are known to be biodegradable ...chlorophenols are unusual among the synthetic compounds discussed here in that they can be very toxic to microorganisms . They are often used as biocides...widely distributed. In contract, bacteria able to grow at the expense of chlorinated aliphatic compounds are less common and the

Degradation of chlorobenzoates and chlorophenols by methanogenic consortia

NARCIS (Netherlands)

Ennik-Maarsen, K.

1999-01-01

Pollution of the environment with chlorinated organic compounds mainly results from (agro)industrial activity. In many studies, biodegradation is examined under anaerobic conditions, because highly chlorinated compounds are more easily degradable under anaerobic than under aerobic

Comparison of Natural and Engineered Chlorophenol Bioremediation Enzymes

Science.gov (United States)

2015-02-26

herein addresses the urgent need to incorporate biological strategies into environmental restoration efforts ( bioremediation ) that focus on the catalytic... Bioremediation Enzymes The views, opinions and/or findings contained in this report are those of the author(s) and should not contrued as an official Department...Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 dehaloperoxidase, bioremediation , halophenol, Amphitrite ornata, marine

A new solid-phase extraction disk based on a sheet of single-walled carbon nanotubes.

Science.gov (United States)

Niu, Hong Yun; Cai, Ya Qi; Shi, Ya Li; Wei, Fu Sheng; Liu, Jie Min; Jiang, Gui Bin

2008-11-01

A new kind of solid-phase extraction disk based on a sheet of single-walled carbon nanotubes (SWCNTs) is developed in this study. The properties of such disks are tested, and different disks showed satisfactory reproducibility. One liter of aqueous solution can pass through the disk within 10-100 min while still allowing good recoveries. Two disks (DD-disk) can be stacked to enrich phthalate esters, bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP) and chlorophenols from various volumes of solution. The results show that SWCNT disks have high extraction ability for all analytes. The SWCNT disk can extract polar chlorophenols more efficiently than a C(18) disk from water solution. Unlike the activated carbon disk, analytes adsorbed by the new disks can be eluted completely with 8-15 mL of methanol or acetonitrile. Finally, the DD-disk system is used to pretreat 1000-mL real-world water samples spiked with BPA, 4-OP and 4-NP. Detection limits of 7, 25, and 38 ng L(-1) for BPA, 4-OP, and 4-NP, respectively, were achieved under optimized conditions. The advantages of this new disk include its strong adsorption ability, its high flow rate and its easy preparation.

Factors Affecting Cis-Dichloroethene and Vinyl Chloride Biological Transformation Under Anaerobic Conditions

Science.gov (United States)

2006-05-01

410. 3. Baek, J-M, and C. M. Kenerley. 1998. Detection and enumeration of a genetically modified fungus in soil environments by quantitative...deduced proteome of D. ethenogenes using the complete sequence of the alcohol dehydrogenase with the most similar N-terminus (accession number ZP_00128696...chlorophenol respiration (3 1). Four orfs similru· to VcrC were also found in the deduced proteome of D. ethenogenes (38 - 47 % identity). Two of those are

Synthesis, spectral and antimicrobial activity of [3-(4-chloro-phenoxy-2,4-diisopropyl-2,3,4,5-tetrahydro-1H-3l5-benzo[e][1,3,2]diazaphosphepin-3-ylidene]-alkyl-amine

Directory of Open Access Journals (Sweden)

R. Usha Nagalakshmi

2009-11-01

Full Text Available 3-(4-chlorophenoxy-2,4-diisopropyl-2,3,4,5-tetrahydro-1H-benzo[e][1,3,2]diaza-phosphepine was synthesized starting from 1,2-bis(bromomethylbenzene by reacting with 2 equimolar isopropyl amine, one equimolar PBr3 and then one equimolar 4-chlorophenol, respectively. The Staudinger reaction of the diazaphphosphine with a series of alkyl azides gave the corresponding iminophosphoranes. Antibacterial activities of the synthesized iminophosphoranes were screened

A novel iron-containing polyoxometalate heterogeneous photocatalyst for efficient 4-chlorophennol degradation by H{sub 2}O{sub 2} at neutral pH

Energy Technology Data Exchange (ETDEWEB)

Zhai, Qian; Zhang, Lizhong [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Zhao, Xiufeng, E-mail: zhaoxiufeng19670@126.com [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Chen, Han; Yin, Dongju [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Li, Jianhui [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

2016-07-30

Graphical abstract: An iron-containing polyoxometalate (Fe{sup III}LysSiW) catalyst showes good performance in the degradation of 4-chlorophenol by H{sub 2}O{sub 2}, especially in irradiated system. The catalytic activity of Fe{sup III}LysSiW stems from synergetic effect of ferric iron for Fenton-like catalysis and SiW{sub 12}O{sub 40}{sup 4−} for photocatalysis, respectively. The chemisorption of H{sub 2}O{sub 2} on Fe{sup III}LysSiW surface by hydrogen bonding also promotes both the Fenton-like and photocatalytic processes. - Highlights: • An iron-containing POM was synthesized as heterogeneous Fenton-like catalyst. • The catalyst has both the Fenton-like and photocatalytic activity at neutral pH. • The activity stems from the co-existence of iron and heteropolyanion in the catalyst. • The hydrogen bonding of H{sub 2}O{sub 2} on the catalyst surface enhances the reaction rate. - Abstract: An iron-containing polyoxometalate (Fe{sup III}LysSiW) was synthesized from ferric chloride (Fe{sup III}), lysine (Lys) and silicotungstic acid (SiW), and characterized using ICP-AES, TG, FT-IR, UV–vis DRS, XRD and SEM. The chemical formula of Fe{sup III}LysSiW was determined as [Fe(H{sub 2}O){sub 5}(C{sub 6}H{sub 14}N{sub 2}O{sub 2})]HSiW{sub 12}O{sub 40}·8H{sub 2}O, with Keggin-structured SiW{sub 12}O{sub 40}{sup 4−} heteropolyanion and lysine moiety. As a heterogeneous catalyst, the as prepared Fe{sup III}LysSiW showed good performance in the degradation of 4-chlorophenol by H{sub 2}O{sub 2} in both the dark and irradiated systems. Under the conditions of 4-chlorophenol 100 mg/L, Fe{sup III}LysSiW 1.0 g/L, H{sub 2}O{sub 2} 20 mmol/L and pH 6.5, 4-chlorophenol could be completely degraded in ca. 40 min in the dark and ca. 15 min upon irradiation. Prolonging the reaction time to 3 h, the TOC removal reached to ca. 71.3% in the dark and ca. 98.8% under irradiation. The catalytic activity of Fe{sup III}LysSiW stems from synergetic effect of ferric iron and Si

[An application of electrochemical detector to dental pharmacology].

Science.gov (United States)

Sakai, J

1990-03-01

The electrochemical detection (ECD) is highly sensitive and can distinguish selectively electrochemically active materials. A sensitive and selective ECD is widely used for high-performance liquid chromatography (HPLC) of phenolic compounds, such as catecholamines, indoleamines and phenolic steroids in biological materials. In the present study, the HPLC/ECD system was applied for the simultaneous determination of various dental drugs, such as phenol, guaiacol, m-cresol, o-chlorophenol, p-chlorophenol, m-chlorophenol, eugenol, pyrogallol and resorcin. As a compromise between sensitivity and stability, the applied voltage was set at 1.2 V vs the reference electrode. These drugs were rapidly and selectively separated on a reversed-phase column using 10 mM acetate buffer (pH 4.0)-methanol (7:3, v/v) as a mobile phase. The detection limits of these drugs were determined to be 0.25 pmol per injection. These results imply that the HPLC/ECD method should be capable of determining these dental drugs with high sensitivity. The ECD was also applied to determine the enzyme activity. A highly sensitive and specific assay for alkaline and acid phosphatases and N-acetyl-beta-glucosaminidase in biological materials, such as plasma, saliva and bone, has been established. Phenol, formed enzymatically from the substrate, was determined by HPLC/ECD. The retention time of phenol was 7 min and no other peaks were observed. The method is rapid and sensitive with a detection limit for phenol of as little as 0.5 pmol. Thus, as little as 0.5 microliters of rat plasma or 10 microliters of human saliva is all that is required for both alkaline and acid phosphatase assays. The assay is accurate and reproducible. Using this assay, alkaline and acid phosphatase activities in human saliva and in rat saliva elicited by pilocarpine and isoproterenol were determined. It will be possible to apply this new assay method to extremely small biological samples. Thus, the application of the HPLC

The synthesis of the carbonyl-14C analog of zatosetron maleate, a potent, long acting, orally effective 5-HT3 receptor antagonist

International Nuclear Information System (INIS)

O'Bannon, D.D.; Wheeler, W.J.

1991-01-01

5-chloro-2,3-dihydro-2,2-dimethyl-N-(8-methyl-8-azabicyclo-[3.2.1.]-oct-3-yl-7-benzofurancarboxamide-[carbonyl- 14 C] (Z)-2-butenedioate (zatosetron-[ 14 C] maleate,1), has been prepared from 5-chloro-7-bromo-2,3-dihydro-2,2-dimethylbenzofuran (5) in four radiochemical steps with the reaction of 5 with K 14 CN/CuCN as the key step. The synthesis of 5 from 2-bromo-4-chlorophenol is also outlined. (author)

Effect of the Mg/Al Ratio on Activated Sol-Gel Hydrotalcites for Photocatalytic Degradation of 2,4,6-Trichlorophenol

Directory of Open Access Journals (Sweden)

Esthela Ramos-Ramírez

2017-01-01

Full Text Available Currently, interest has grown in finding effective solutions for the treatment of water pollution by toxic compounds. Some of the latter that have acquired importance are phenols and chlorophenols, due to their employment in the manufacture of pesticides, insecticides, cords of wood, paper industry, among others. The problem is rooted in that these compounds are very persistent in the environment because they are partially biodegradable and cannot be photodegraded directly by sunlight. Chlorophenols are extremely toxic, especially 2,4,6-trichlorophenol, which is potentially carcinogenic. In this work, Mg/Al-mixed oxide catalysts were obtained from the thermal treatment of hydrotalcite-type materials, synthesized by sol-gel method with different Mg/Al ratios. Hydrotalcites and Mg/Al-mixed oxides were physicochemically characterized by X-ray diffraction, thermal analysis (DTA and TGA, and N2 physisorption. The results were obtained on having proven the photocatalytic degradation of 2,4,6-trichlorophenol as a pollutant model by water. The catalysts obtained present the hydrotalcite phase with thermal evolution until achieving Mg/Al-mixed oxides at 500°C. The catalysts are of mesoporous materials and exhibiting large surface areas. The catalysts demonstrated good photocatalytic activity with good efficiency, reaching degradation percentages with Mg/Al = 1, 2, 4, 5, and 7 ratios of 94.2, 92.5, 86.2, 84.2, and 63.9%, respectively, until achieving mineralization.

Electrochemical treatment of wastewater: A case study of reduction of DNT and oxidation of chlorinated phenols

Energy Technology Data Exchange (ETDEWEB)

Rodgers, J.D.; Bunce, N.J.; Jedral, W.

1999-07-01

Electrochemical treatment is under consideration as a treatment option for several recalcitrant compounds. In this work the authors investigate the oxidation of chlorophenols and the reduction of nitroaromatics. In the case of chlorinated phenols, they explore the problem of anode fouling which has hampered electrolytic treatment of phenolic compounds by examining phenols differing in the extent of chlorination, according to the mechanism of oxidation at different electrode types. Linear sweep voltammograms at a Pt anode were interpreted in terms of deposition of oligomers on the anode surface. Passivation increased in parallel with the uncompensated resistance of the solution and occurred only at potentials at which water is oxidized, suggesting that the formation of the oligomer film involves attack of hydroxyl radicals on electrochemically oxidized substrate. Relative reactivities of congeners were anode-dependent, due to different mechanisms of oxidation: direct electron transfer oxidation at PbO{sub 2} and hydroxyl radical attack at SnO{sub 2} and IrO{sub 2}. Voltammetry of 2,6-dinitrotoluene (DNT) was consistent with literature values. DNT was reduced at several cathodes with the most promising result at Ni-plated Ni wire. At current densities {lt} 0.1 mA cm{sup {minus}2}, current efficiencies {gt} 50% could be achieved with 4-chlorophenol at all three anodes and for 2,6-DNT at Ni-plated Ni wire.

Self-bioremediation of cork-processing wastewaters by (chloro)phenol-degrading bacteria immobilised onto residual cork particles.

Science.gov (United States)

del Castillo, I; Hernández, P; Lafuente, A; Rodríguez-Llorente, I D; Caviedes, M A; Pajuelo, E

2012-04-15

Cork manufacturing is a traditional industry in Southern Europe, being the main application of this natural product in wine stoppers and insulation. Cork processing begins at boiling the raw material. As a consequence, great volumes of dark wastewaters, with elevated concentrations of chlorophenols, are generated, which must be depurated through costly physicochemical procedures before discarding them into public water courses. This work explores the potential of bacteria, isolated from cork-boiling waters storage ponds, in bioremediation of the same effluent. The bacterial population present in cork-processing wastewaters was analysed by DGGE; low bacterial biodiversity was found. Aerobic bacteria were isolated and investigated for their tolerance against phenol and two chlorophenols. The most tolerant strains were identified by sequencing 16S rDNA. The phenol-degrading capacity was investigated by determining enzyme activities of the phenol-degrading pathway. Moreover, the capacity to form biofilms was analysed in a microtitre plate assay. Finally, the capacity to form biofilms onto the surface of residual small cork particles was evaluated by acridine staining followed by epifluorescence microscopy and by SEM. A low-cost bioremediation system, using phenol-degrading bacteria immobilised onto residual cork particles (a by-product of the industry) is proposed for the remediation of this industrial effluent (self-bioremediation). Copyright © 2011 Elsevier Ltd. All rights reserved.

Detection of 14C - lindane metabolites in coffee plants by thin-layer chromatography and autoradiography

International Nuclear Information System (INIS)

Mesquita, T.B.; Hirata, R.; Ruegg, E.F.

1986-01-01

Immersion of seedling from coffee plants in aquous solution of 14 C - lindane was done for 60 days. The insecticide was taken up the roots and translocated to the stems and leaves. However, chromatographic assays indicated that several metabolites were detected only in the roots. Two of them probably are chlorobenzenes and were visualized in chromatograms of extracts from non-acidic fractions. Seven other radioactive spots which are suspected to be chlorophenols, were found in the acidic fractions. (Author) [pt

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

DEFF Research Database (Denmark)

Mines, Paul D.; Kaarsholm, Kamilla Marie Speht; Droumpali, Ariadni

2017-01-01

, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster...... reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we...

Parabola-like shaped pH-rate profile for phenols oxidation by aqueous permanganate.

Science.gov (United States)

Du, Juanshan; Sun, Bo; Zhang, Jing; Guan, Xiaohong

2012-08-21

Oxidation of phenols by permanganate in the pH range of 5.0-9.0 generally exhibits a parabola-like shape with the maximum reaction rate obtained at pH close to phenols' pK(a). However, a monotonic increase or decrease is observed if phenols' pK(a) is beyond the pH range of 5.0-9.0. A proton transfer mechanism is proposed in which the undissociated phenol is directly oxidized by permanganate to generate products while a phenolate-permanganate adduct, intermediate, is formed between dissociated phenol and permanganate ion and this is the rate-limiting step for phenolates oxidation by permanganate. The intermediate combines with H(+) and then decomposes to products. Rate equations derived based on the steady-state approximation can well simulate the experimentally derived pH-rate profiles. Linear free energy relationships (LFERs) were established among the parameters obtained from the modeling, Hammett constants, and oxygen natural charges in phenols and phenolates. LFERs reveal that chlorine substituents have opposite influence on the susceptibility of phenols and phenolates to permanganate oxidation and phenolates are not necessarily more easily oxidized than their neutral counterparts. The chlorine substituents regulate the reaction rate of chlorophenolates with permanganate mainly by influencing the natural charges of the oxygen atoms of dissociated phenols while they influence the oxidation of undissociated chlorophenols by permanganate primarily by forming intramolecular hydrogen bonding with the phenolic group.

Cancer incidence and specific occupational exposures in the Swedish leather tanning industry: a cohort based case-control study.

Science.gov (United States)

Mikoczy, Z; Schütz, A; Strömberg, U; Hagmar, L

1996-01-01

OBJECTIVE--To study the effect on the incidence of cancer of exposure to chemicals handled in the leather tanning industry. MATERIALS AND METHODS--A case-control study was performed within a cohort of 2487 workers employed for at least six months during the period 1900-89 in three Swedish leather tanneries. 68 cancer cases (lung, stomach, bladder, kidney, nasal, and pancreatic cancers and soft tissue sarcomas) and 178 matched controls were studied. Effects of chemical exposures on cancer incidence, adjusted for age at risk, sex, and plant were estimated with a conditional logistic regression model. RESULTS--A significant association was found between exposure to leather dust and pancreatic cancer (odds ratio (OR) 7.19, 95% confidence interval (95% CI) 1.44 to 35-89). An association was indicated between leather dust from vegetable tanning and lung cancer. After adjustment for smoking habits a tentative association between organic solvents and lung cancer lost its significance. No association was found between exposure to chlorophenols and soft tissue sarcomas. CONCLUSIONS--The significant association between leather tanning and soft tissue sarcomas that was found in our previous cohort analysis could not be explained by exposure to chlorophenols. On the other hand a significant association was found between exposure to leather dust and pancreatic cancer, and exposure to leather dust from vegetable tanning was often present in cases with lung cancer. Due to the small numbers of cases, the results can, however, only lead to tentative conclusions. PMID:8704870

Need for organic reference materials in marine science

Energy Technology Data Exchange (ETDEWEB)

Wells, D.E.

1988-12-01

The reference materials (RMs) available for organic trace analysis (OTA) and the development programmes of the RM producers are reviewed. The need for a wider range of determinants, matrices and classes of RMs, particularly the more widespread use of laboratory RMs (LRMs) is discussed. Additional certified RMs should include phenolic surfactant degradation products, chlorophenolics from the wood and paper industries, and organobromines from fire retardants. RMs as molecular markers of geogenic, pyrogenic and biogenic sources; chlorophylls and xanthophylls as a measure of marine productivity and natural shellfish toxins are proposed.

Uranyl(VI) and lanthanum(III) complexes with functionalized macrocyclic and macroacyclic Schiff bases

International Nuclear Information System (INIS)

Aguiari, A.; Brianese, N.; Tamburini, S.; Vigato, P.A.

1995-01-01

Acyclic Schiff bases have been prepared by [2 + 1] condensation of 2,6-diformyl-4-chlorophenol and H 2 NCH 2 [CH 2 XCH 2 ] n CH 2 NH 2 (n =3D 0 H 2 -I; X =3D NH, S, O n =3D 1 H 2 -II...H 2 -IV; X =3D 0 n =3D 2 H 2 -V; X =3D 0 n =3D 3 H 2 -VI). The related uranlyl(VI) and lanthanum (III) complexes have bee synthesized by reaction by reaction of the preformed ligands with the appropriate salt or by the template procedure, in the presence of base. No base was employed in the preparation of lanthanum (III) complexes, La(H 2 -II)(NO 3 ) 3 , La(H 2 -IV)(NO 3 ) 3 where the Schiff bases coordinate as neutral chelate ligands. These acyclic complexes have been used for further condensation, and symmetric and asymmetric cyclic complexes have been obtained by their reaction with the polyamines H 2 NCH 2 [CH 2 XCH 2 ]nCH 2 NH 2 or with 4,4'-diaminodibenzo -18-crown-6. By reaction with 4-aminobenzo-15-crown-5 or 2-amino-methyl-15-crown-5, the same acyclic complexes give rise to functionalized complexes bearing crown-ether moieties. Analogously, the acyclic ligand H 3 -IXX, prepared by condensation of 2,6 diformyl-4-chlorophenol and tris(aminoethyl)amine, forms mono and homodinuclear lanthanum (III) complexes, which may undergo further condensation when reacted with primary functionalized amines. (authors). 42 refs., 2 figs., 2 schemes, 1 tab

Biosorption of Phenolic Compounds from Aqueous Solutions using Pine (Pinus densiflora Sieb Bark Powder

Directory of Open Access Journals (Sweden)

Siva Kumar Nadavala

2014-07-01

Full Text Available The present study describes the development of a new bioadsorbent from lignocellulosic wastes of agricultural origin. The biosorption capacity of an agricultural solid waste, pine bark (Pinus densiflora Sieb., to remove phenolic compounds (phenol, 2-chlorophenol (2-CPh, and 4- chlorophenol (4-CPh from aqueous solutions under batch equilibrium conditions was investigated. The morphological characteristics of the biosorbent were evaluated by BET surface area analysis, Fourier transform infrared spectroscopy (FTIR, elemental analysis, an X-ray diffractometer (XRD, and a scanning electron microscope (SEM. Batch experiments were conducted to investigate the effect of initial pH (2 to 10, contact time, initial concentration of adsorbate (50 to 200 mg/L, and biosorbent dosage. The biosorption of phenolic compounds decreased with increasing pH, and the highest biosorption capacity was achieved at a pH of 6.0. Biosorption equilibrium was established in 120 min. The biosorption equilibrium data were fitted and analyzed with Langmuir, Freundlich, and Dubinin-Radushkevich isotherm equations, as well as four adsorption kinetic models. The kinetics data fitted well into the pseudo-second-order kinetic model, with a correlation coefficient greater than 0.993. The maximum monolayer biosorption capacity of pine bark for phenol, 2-CPh, and 4-CPh was found to be 142.85, 204.08, and 263.15 mg/g, respectively, as calculated by the Langmuir model at 30 ± 1 °C. Pine bark could be used as a new effective, low-cost biosorbent material with good uptake capacity and rapid kinetics for the removal of phenolic compounds from aqueous media.

Regeneration strategies of polymers employed in ex-situ remediation of contaminated soil: Bioregeneration versus solvent extraction.

Science.gov (United States)

Mosca Angelucci, Domenica; Tomei, M Concetta

2015-08-15

In this study we evaluated the feasibility of two regeneration strategies of contaminated polymers employed for ex-situ soil remediation in a two-step process. Soil decontamination is achieved by sorption of the pollutants on the polymer beads, which are regenerated in a subsequent step. Tested soil was contaminated with a mixture of 4-chlorophenol and pentachlorophenol, and a commercial polymer, Hytrel, has been employed for extraction. Removal efficiencies of the polymer-soil extraction are in the range of 51-97% for a contact time ≤ 24 h. Two polymer regeneration strategies, solvent extraction and biological regeneration (realized in a two-phase partitioning bioreactor), were tested and compared. Performance was assessed in terms of removal rates and efficiencies and an economic analysis based on the operating costs has been performed. Results demonstrated the feasibility of both regeneration strategies, but the bioregeneration was advantageous in that provided the biodegradation of the contaminants desorbed from the polymer. Practically complete removal for 4-chlorophenol and up to 85% biodegradation efficiency for pentachlorophenol were achieved. Instead, in the solvent extraction, a relevant production (184-831 L kg(pol)(-1)) of a highly polluted stream to be treated or disposed of is observed. The cost analysis of the two strategies showed that the bioregeneration is much more convenient with operating costs of ∼12 €/kg(pol) i.e. more than one order of magnitude lower in comparison to ∼233 €/kg(pol) of the solvent extraction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improvement in rice straw pulp bleaching effluent quality by incorporating oxygen delignification stage prior to elemental chlorine-free bleaching.

Science.gov (United States)

Kaur, Daljeet; Bhardwaj, Nishi K; Lohchab, Rajesh Kumar

2017-10-01

Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD 3 , COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources. Graphical abstract ᅟ.

Interaction of 2,4,6-trichlorophenol with high carbon iron filings: Reaction and sorption mechanisms

Energy Technology Data Exchange (ETDEWEB)

Sinha, Alok [Environmental Engineering and Management Programme, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Bose, Purnendu [Environmental Engineering and Management Programme, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)], E-mail: pbose@iitk.ac.in

2009-05-15

Reductive dehalogenation of 2,4,6-trichlorophenol (2,4,6-TCP) by two types of high carbon iron filings (HCIF), HCIF-1 and HCIF-2 was studied in batch reactors. While the iron, copper, manganese and carbon content of the two types of HCIF was similar, the specific surface area of HCIF-1 and HCIF-2 were 1.944 and 3.418 m{sup 2} g{sup -1}, respectively. During interaction with HCIF-1, 2,4,6-TCP adsorbed on HCIF-1 surface resulting in rapid reduction of aqueous phase 2,4,6-TCP concentration. However, reductive dehalogenation of 2,4,6-TCP was negligible. During interaction between 2,4,6-TCP and HCIF-2, both 2,4,6-TCP adsorption on HCIF-2, and 2,4,6,-TCP dechlorination was observed. 2,4,6-TCP partitioning between solid and aqueous phase could be described by a Freundlich isotherm, while 2,4,6-TCP dechlorination could be described by an appropriate rate expression. A mathematical model was developed for describing the overall interaction of 2,4,6-TCP with HCIF-2, incorporating simultaneous adsorption/desorption and dechlorination reactions of 2,4,6-TCP with the HCIF surface. 2,4-Dichlorophenol (2,4-DCP), 2-chlorophenol (2-CP) and minor amounts of 4-chlorophenol (4-CP) evolved as 2,4,6-TCP dechlorination by-products. The evolved 2,4-DCP partitioned strongly to the HCIF surface. 4-CP and 2-CP accumulated in the aqueous phase. No transformation of 2-CP or 4-CP to phenol was observed.

Purification and characterization of the 3-chloro-4-hydroxy-phenylacetate reductive dehalogenase of Desulfitobacterium hafniense

DEFF Research Database (Denmark)

Christensen, Nina; Ahring, Birgitte Kiær; Wohlfarth, Gert

1998-01-01

The membrane-bound 3-chloro-4-hydroxyphenylacetate (Cl-OHPA) reductive dehalogenase from the chlorophenol- educing anaerobe Desulfitobacterium hafniense was purified 11.3-fold to apparent homogeneity in the presence of the detergent CHAPS. The purified dehalogenase catalyzed the reductive...... dechlorination of Cl-OHPA to 4-hydroxyphenylacetate with reduced methyl viologen as the electron donor at a specific activity of 103.2 nkat/mg protein. SDS-PAGErevealed a single protein band with an apparent molecular mass of 46.5 kDa. The enzyme contained 0.68±0.2 mol corrinoid, 12.0±0.7 mol iron, and 13...

Determination of Chlorine Dioxide and Chlorite in Water Supply Systems by Verified Methods

Directory of Open Access Journals (Sweden)

Tkáčová Jana

2014-07-01

Full Text Available This work is dedicated to the development and optimization of appropriate analytical methods for the determination of chlorine dioxide and chlorite in drinking water in order to obtain accurate and correct results in the quality control of drinking water. The work deals with the development and optimization of a method for the determination of chlorine dioxide using chlorophenol red. Furthermore, a new spectrophotometric method for the determination of chlorite via bromometry using methyl orange was developed, optimized and validated. An electrochemical method for the determination of chlorite by flow coulometry was also developed, optimized and validated.

Destruction of chlorine-containing organic agents in a system plasma - liquid

International Nuclear Information System (INIS)

Chernyak, V.Ya.; Yukhymenko, V.V.; Babich, I.L.; Slyusarenko, Y.I.; Tarasova, Ya.B.

2005-01-01

The plasma chemical destruction of persistent toxic agent 1,1-di(4-chlorophenol)-2,2,2-threechlorethane (DDT) in water solutions is researched in this work. The destruction of agricultural pesticide containing DDT was carried out in water solution at atmospheric pressure with usage of plasma treatment on the basis of secondary discharges with a 'liquid' electrode, and of combination of a plasma method with reagent method. The comparative analysis of results of the physical-chemical analysis and biological test of toxicity of solutions is carried out and the optimum regimes for destruction and detoxication of DDT in water are determined

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

Science.gov (United States)

Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

2015-12-01

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

Efeito de gomas de mascar contendo clorofenol / peróxido de hidrogênio, xilitol ou clorexidina no fluxo salivar, pH, capacidade tampão e escores salivares de Streptococcus mutans = Effects of chlorophenol / hydrogen peroxide versus xylitol or chlorhexidine as chewing gum on salivary flow rate, pH, buffer capacity and salivary Streptococcus mutans scores

Directory of Open Access Journals (Sweden)

Yévenes López, Ismael

2014-01-01

Full Text Available Objetivos: Gomas de mascar medicadas são preparações sólidas, de dose única, que devem ser mastigadas por um determinado período de tempo a fim de que um ou mais agentes farmacológicos sejam admnistrados. Neste contexto, gomas de mascar medicadas com três ingredientes farmacêuticos ativos – cânfora, p-clorofenol e peróxido de hidrogênio – foram avaliadas como agentes terapêuticos para cárie dentária. O objetivo deste estúdio foi comparar o efeito de gomas de mascar contendo chlorophenol / peróxido de hidrogênio, xilitol ou clorexidina sobre Streptococos mutans salivares, pH, capacidade tampão, a taxa de secreção salivar. Métodos: Foi realizado estudo duplo-cego, com deliamento de randomização cruzada de tratamento em 24 pacientes. Esses foram submetidos a seis sequências diferentes de tratamento. Gomas de mascar foram administradas três vezes ao dia durante 20 minutos, pela manhã, tarde e noite. No início e no final das três fases de amostras de saliva experimentais foram obtidas para a determinação de pH, capacidade tampão, fluxo salivar e enumeração quantitativa de S. mutans. Resultados: O uso de goma medicado de cânfora com p-clorofenol e peróxido de hidrogénio não modificaram os parâmetros químicos salivares medidos, e reduziram o número de S. mutans, após 7 dias. Gomas de mascar contendo clorexidina reduziram significativamente a contagem quantitativa de S. mutans e a taxa de fluxo salivar em um período de 7 dias. Conclusões: O uso de gomas de mascar medicadas com base de cânfora / p-clorofenol ou com peróxido de hidrogênio não altera significativamente os parâmetros químicos salivares e não reduz significativamente o número de S. mutans após a utilização por período de 7 dias

Uptake, removal, accumulation, and phytotoxicity of 4-chlorophenol in willow trees

DEFF Research Database (Denmark)

Ucisik, Ahmed Süheyl; Trapp, Stefan

2008-01-01

of implementing phytoremediation as a treatment method for 4-CP contamination was investigated. Willows were exposed to 4-CP levels ≤79.9 mg/L in hydroponic solution. The transpiration of the trees was used to determine toxic effects. Almost no inhibition of transpiration was detected at concentrations ≥15 mg...

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

Energy Technology Data Exchange (ETDEWEB)

Hao Xiaolong [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Zhou Ming Hua [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Lei Lecheng [Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China)]. E-mail: lclei@zju.edu.cn

2007-03-22

TiO{sub 2} photocatalyst (P-25) (50 mg L{sup -1}) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO{sub 2} were obviously increased. Pulsed high-voltage discharge process with TiO{sub 2} had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10{sup -6} to 1.50 x 10{sup -6} M s{sup -1}, the ozone formation rate from 1.99 x 10{sup -8} to 2.35 x 10{sup -8} M s{sup -1}, respectively. In addition, this process had no influence on the photocatalytic properties of TiO{sub 2}. The introduction of TiO{sub 2} photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water.

Science.gov (United States)

Hao, Xiao Long; Zhou, Ming Hua; Lei, Le Cheng

2007-03-22

TiO(2) photocatalyst (P-25) (50mgL(-1)) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO(2) were obviously increased. Pulsed high-voltage discharge process with TiO(2) had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10x10(-6) to 1.50x10(-6)Ms(-1), the ozone formation rate from 1.99x10(-8) to 2.35x10(-8)Ms(-1), respectively. In addition, this process had no influence on the photocatalytic properties of TiO(2). The introduction of TiO(2) photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants.

Degradation of chlorophenol mixtures in a fed-batch system by two ...

African Journals Online (AJOL)

2010-12-16

Dec 16, 2010 ... water is fed to the biological treatment unit either intermittently or ... the same culture in a binary mixture and in ternary mixture of 2,4,6TCP; 2,3,5 .... Solving the balance equation (Eq. (2)) with the initial condi- tions of the ...

Non-thermal plasma-induced photocatalytic degradation of 4-chlorophenol in water

International Nuclear Information System (INIS)

Hao Xiaolong; Zhou Ming Hua; Lei Lecheng

2007-01-01

TiO 2 photocatalyst (P-25) (50 mg L -1 ) was tentatively introduced into pulsed high-voltage discharge process for non-thermal plasma-induced photocatalytic degradation of the representative mode organic pollutant parachlorophenol (4-CP), including other compounds phenol and methyl red in water. The experimental results showed that rate constant of 4-CP degradation, energy efficiency for 4-CP removal and TOC removal with TiO 2 were obviously increased. Pulsed high-voltage discharge process with TiO 2 had a promoted effect for the degradation of these pollutants under a broad range of liquid conductivity. Furthermore, the apparent formation rates of chemically active species (e.g., ozone and hydrogen peroxide) were increased, the hydrogen peroxide formation rate from 1.10 x 10 -6 to 1.50 x 10 -6 M s -1 , the ozone formation rate from 1.99 x 10 -8 to 2.35 x 10 -8 M s -1 , respectively. In addition, this process had no influence on the photocatalytic properties of TiO 2 . The introduction of TiO 2 photocatalyst into pulsed discharge plasma process in the utilizing of ultraviolet radiation and electric field in pulsed discharge plasma process enhanced the yields of chemically active species, which were available for highly efficient removal and mineralization of organic pollutants

Degradation of chlorophenol mixtures in a fed-batch system by two ...

African Journals Online (AJOL)

This work was undertaken to investigate the effect of variations of the feed rate on a fed-batch set-up used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2,4,6 TCP and 2,3,5,6 TeCP (pentachlorophenol, 2,4,6 trichlorophenol and 2,3,5,6 tetrachlorophenol respectively). Two acclimated bacteria ...

Effect of magnetic field on the zero valent iron induced oxidation reaction

International Nuclear Information System (INIS)

Kim, Dong-hyo; Kim, Jungwon; Choi, Wonyong

2011-01-01

Highlights: → We investigate the zero valent iron induced oxidation in the presence of magnetic field. → The oxidative degradation of 4-chlorophenol is enhanced by the magnetic field. → ESR measurement confirms that more OH radicals are generated in the presence of magnetic field. → The magnetic field affects the mass transfer of O 2 and the recombination of radicals. - Abstract: The magnetic field (MF) effect on the zero valent iron (ZVI) induced oxidative reaction was investigated for the first time. The degradation of 4-chlorophenol (4-CP) in the ZVI system was employed as the test oxidative reaction. MF markedly enhanced the degradation of 4-CP with the concurrent production of chlorides. The consumption of dissolved O 2 by ZVI reaction was also enhanced in the presence of MF whereas the competing reaction of H 2 production from proton reduction was retarded. Since the ZVI-induced oxidation is mainly driven by the in situ generated hydroxyl radicals, the production of OH radicals was monitored by the spin trap method using electron spin resonance (ESR) spectroscopy. It was confirmed that the concentration of trapped OH radicals was enhanced in the presence of MF. Since both O 2 and Fe 0 are paramagnetic, the diffusion of O 2 onto the iron surface might be accelerated under MF. The magnetized iron can attract oxygen on itself, which makes the mass transfer process faster. As a result, the surface electrochemical reaction between Fe 0 and O 2 can be accelerated with the enhanced production of OH radicals. MF might retard the recombination of OH radicals as well.

μ-Acetato-κ2O:O′-[7,23-dibenzyl-15,31-dichloro-3,7,11,19,23,27-hexaazatricyclo[27.3.1.113,17]tetratriconta-1(32,2,11,13,15,17(34,18,27,29(33,30-decaene-33,34-diolato-κ10N4,N5,N6,O1,O2:N1,N2,N3,O1,O2]dinickel(II perchlorate acetonitrile disolvate

Directory of Open Access Journals (Sweden)

Juan Kong

2008-01-01

Full Text Available The title complex, [Ni2(C42H46Cl2N6O2(C2H3O2]ClO4·2CH3CN, was synthesized by condensation of 2,6-diformyl-4-chlorophenol with N,N-bis(aminopropylbenzylamine in the presence of NiII ions. The ligand is a 28-membered macrocycle with two identical pendant arms. The coordination geometries of the Ni atoms are both octahedral. The two Ni atoms are bridged by two phenolate O atoms of the macrocyclic ligand and one acetate ligand, with an Ni...Ni distance of 3.147 (4 Å.

Scale up of 2,4-dichlorophenol removal from aqueous solutions using Brassica napus hairy roots

Energy Technology Data Exchange (ETDEWEB)

Angelini, Vanina A. [Departamento de Biologia Molecular, FCEFQN, Universidad Nacional de Rio Cuarto, 5800 Rio Cuarto, Cordoba (Argentina); Orejas, Joaquin [Facultad de Ingenieria, Universidad Nacional de Rio Cuarto, 5800 Rio Cuarto, Cordoba (Argentina); Medina, Maria I. [Departamento de Biologia Molecular, FCEFQN, Universidad Nacional de Rio Cuarto, 5800 Rio Cuarto, Cordoba (Argentina); Agostini, Elizabeth, E-mail: eagostini@exa.unrc.edu.ar [Departamento de Biologia Molecular, FCEFQN, Universidad Nacional de Rio Cuarto, 5800 Rio Cuarto, Cordoba (Argentina)

2011-01-15

Research highlights: {yields}B. napus hairy roots were effectively used for a large scale removal of 2,4-DCP. {yields} High removal efficiencies were obtained (98%) in a short time (30 min). {yields} Roots were re-used for six consecutive cycles with high efficiency. {yields} Post removal solutions showed no toxicity. {yields} This method could be used for continuous and safe treatment of phenolic effluents. - Abstract: Chlorophenols are harmful pollutants, frequently found in the effluents of several industries. For this reason, many environmental friendly technologies are being explored for their removal from industrial wastewaters. The aim of the present work was to study the scale up of 2,4-dichlorophenol (2,4-DCP) removal from synthetic wastewater, using Brassica napus hairy roots and H{sub 2}O{sub 2} in a discontinuous stirred tank reactor. We have analyzed some operational conditions, because the scale up of such process was poorly studied. High removal efficiencies were obtained (98%) in a short time (30 min). When roots were re-used for six consecutive cycles, 2,4-DCP removal efficiency decreased from 98 to 86%, in the last cycle. After the removal process, the solutions obtained from the reactor were assessed for their toxicity using an acute test with Lactuca sativa L. seeds. Results suggested that the treated solution was less toxic than the parent solution, because neither inhibition of lettuce germination nor effects in root and hypocotyl lengths were observed. Therefore, we provide evidence that Brassica napus hairy roots could be effectively used to detoxify solutions containing 2,4-DCP and they have considerable potential for a large scale removal of this pollutant. Thus, this study could help to design a method for continuous and safe treatment of effluents containing chlorophenols.

Towards a continuous two-phase partitioning bioreactor for xenobiotic removal

Energy Technology Data Exchange (ETDEWEB)

Tomei, M.Concetta, E-mail: tomei@irsa.cnr.it [Water Research Institute, C.N.R., Via Salaria km 29.300, CP 10, 00015 Monterotondo Stazione, Rome (Italy); Mosca Angelucci, Domenica [Water Research Institute, C.N.R., Via Salaria km 29.300, CP 10, 00015 Monterotondo Stazione, Rome (Italy); Daugulis, Andrew J. [Department of Chemical Engineering, Queen’s University, Kingston, Ontario K7 L 3N6 (Canada)

2016-11-05

Highlights: • A prototype of a continuous two-phase partitioning bioreactor was investigated. • The bioreactor contained coiled tubing of a selected extruded polymer, Hytrel 8206. • Mass transfer and removal of a xenobiotic, 4-cholorophenol, were investigated. • Removal efficiencies in the tubing wastewater stream were always ≥ 96%. • Presence of polymer tubing buffered increasing in organic load to the hybrid system. - Abstract: The removal of a xenobiotic (4-chlorophenol) from contaminated water was investigated in a simulated continuous two-phase partitioning bioreactor (C-TPPB), fitted with coiled tubing comprised of a specifically-selected extruded polymer, Hytrel 8206. Wastewater flowed inside the tubing, the pollutant diffused through the tubing wall, and was removed in the aqueous bioreactor phase at typical biological removal rates in the C-TTPB simulated by varying aqueous phase throughput to the reactor. Operating over a range of influent substrate concentrations (500–1500 mg L{sup −1}) and hydraulic retention times in the tubing (4–8 h), overall mass transfer coefficients were 1.7–3.5 × 10{sup −7} m s{sup −1}, with the highest value corresponding to the highest tubing flow rate. Corresponding mass transfer rates are of the same order as biological removal rates, and thus do not limit the removal process. The C-TPPB showed good performance over all organic and hydraulic loading ranges, with removal efficiencies of 4CP in the tubing wastewater stream always ≥96%. Additionally, the presence of the Hytrel tubing was able to buffer increases in organic loading to the hybrid system, enhancing overall process stability. Biological testing of the C-TPPB confirmed the abiotic test results demonstrating even higher 4-chlorophenol removal efficiency (∼99%) in the tubing stream.

Polyphasic characterization of a PCP-to-phenol dechlorinating microbial community enriched from paddy soil

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Naoko [EcoTopia Science Institute, Nagoya University Nagoya 464-8603 (Japan)]. E-mail: ysd75@esi.nagoya-u.ac.jp; Yoshida, Yukina [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Handa, Yuko [Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Kim, Hyo-Keun [Korea Ginseng and Tobacco Research Institute, Taejon 305-345 (Korea, Republic of); Ichihara, Shigeyuki [Faculty of Agriculture, Meijo University, Nagoya 468-8502 (Japan); Katayama, Arata [EcoTopia Science Institute, Nagoya University Nagoya 464-8603 (Japan); Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)

2007-08-01

Dechlorination of PCP has been observed previously under anaerobic condition in paddy soil. However, there is poor information about the dechlorination pathway of PCP and the microbial community associated with the PCP dechlorination in paddy soil. In this study, an anaerobic microbial community dechlorinating PCP was enriched by serial transfers from a paddy soil using a medium containing PCP, lactate and the steam-sterilized paddy soil. The enriched microbial community dechlorinated PCP completely to phenol under the anaerobic condition by a dechlorinating pathway as follows; PCP {sup {yields}} 2,3,4,5-tetrachlorophenol {sup {yields}} 3,4,5-trichlorophenol {sup {yields}} 3,5-dichlorophenol {sup {yields}} 3-chlorophenol {sup {yields}} phenol. Intermediate products such as 3-chlorophenol were not accumulated, which were immediately dechlorinated to phenol. The enriched microbial community was characterized physiologically by testing the effects of electron donors and electron acceptors on the dechlorinating activity. The dechlorinating activity was promoted with lactate, pyruvate, and hydrogen as electron donors but not with acetate. Electron acceptors, nitrate and sulphate, inhibited the dechlorinating activity competitively but not iron (III). The microbial group associated with the anaerobic dechlorination was characterized by the effect of specific inhibitors on the PCP dechlorination. Effects of specific metabolic inhibitors and antibiotics indicated the involvement of Gram-positive spore-forming bacteria with the PCP dechlorinating activity, which was represented as bacteria of phylum Firmicutes. The structure of the microbial community was characterized by fluorescence in situ hybridization, quinone profiling, and PCR-DGGE (denaturing gel gradient electrophoresis). The combined results indicated the predominance of Clostridium species of phylum Firmicutes in the microbial community. Desulfitobacterium spp. known as anaerobic Gram-positive spore

Scale up of 2,4-dichlorophenol removal from aqueous solutions using Brassica napus hairy roots

International Nuclear Information System (INIS)

Angelini, Vanina A.; Orejas, Joaquin; Medina, Maria I.; Agostini, Elizabeth

2011-01-01

Research highlights: →B. napus hairy roots were effectively used for a large scale removal of 2,4-DCP. → High removal efficiencies were obtained (98%) in a short time (30 min). → Roots were re-used for six consecutive cycles with high efficiency. → Post removal solutions showed no toxicity. → This method could be used for continuous and safe treatment of phenolic effluents. - Abstract: Chlorophenols are harmful pollutants, frequently found in the effluents of several industries. For this reason, many environmental friendly technologies are being explored for their removal from industrial wastewaters. The aim of the present work was to study the scale up of 2,4-dichlorophenol (2,4-DCP) removal from synthetic wastewater, using Brassica napus hairy roots and H 2 O 2 in a discontinuous stirred tank reactor. We have analyzed some operational conditions, because the scale up of such process was poorly studied. High removal efficiencies were obtained (98%) in a short time (30 min). When roots were re-used for six consecutive cycles, 2,4-DCP removal efficiency decreased from 98 to 86%, in the last cycle. After the removal process, the solutions obtained from the reactor were assessed for their toxicity using an acute test with Lactuca sativa L. seeds. Results suggested that the treated solution was less toxic than the parent solution, because neither inhibition of lettuce germination nor effects in root and hypocotyl lengths were observed. Therefore, we provide evidence that Brassica napus hairy roots could be effectively used to detoxify solutions containing 2,4-DCP and they have considerable potential for a large scale removal of this pollutant. Thus, this study could help to design a method for continuous and safe treatment of effluents containing chlorophenols.

Superoxide radical-mediated photocatalytic oxidation of phenolic compounds over Ag"+/TiO_2: Influence of electron donating and withdrawing substituents

International Nuclear Information System (INIS)

Xiao, Jiadong; Xie, Yongbing; Han, Qingzhen; Cao, Hongbin; Wang, Yujiao; Nawaz, Faheem; Duan, Feng

2016-01-01

Highlights: • A weak EWG benefited photocatalytic oxidation of phenols the most. • Phenolic compounds were dominantly oxidized by ·O_2"−, rather than ·OH, "1O_2 or h"+. • ·O_2"− preferred to nucleophilically attack EDG substituted phenols. • ·O_2"− more likely electrophilically attacked EWG substituted phenols. • ·O_2"− simultaneously nucleophilically and electrophilically assaulted p-chlorophenol. - Abstract: A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag"+/TiO_2 suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p-benzoquinone dramatically blocked the degradation, confirming superoxide radicals (·O_2"−) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between ·O_2"− and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of ·O_2"− and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by ·O_2"−, while ·O_2"− preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by ·O_2"− could simultaneously occur in p-chlorophenol degradation, consequently leading to its highest rate constant. Possible reactive positions on the phenolic compounds were also detailedly uncovered.

Polyphasic characterization of a PCP-to-phenol dechlorinating microbial community enriched from paddy soil

International Nuclear Information System (INIS)

Yoshida, Naoko; Yoshida, Yukina; Handa, Yuko; Kim, Hyo-Keun; Ichihara, Shigeyuki; Katayama, Arata

2007-01-01

Dechlorination of PCP has been observed previously under anaerobic condition in paddy soil. However, there is poor information about the dechlorination pathway of PCP and the microbial community associated with the PCP dechlorination in paddy soil. In this study, an anaerobic microbial community dechlorinating PCP was enriched by serial transfers from a paddy soil using a medium containing PCP, lactate and the steam-sterilized paddy soil. The enriched microbial community dechlorinated PCP completely to phenol under the anaerobic condition by a dechlorinating pathway as follows; PCP → 2,3,4,5-tetrachlorophenol → 3,4,5-trichlorophenol → 3,5-dichlorophenol → 3-chlorophenol → phenol. Intermediate products such as 3-chlorophenol were not accumulated, which were immediately dechlorinated to phenol. The enriched microbial community was characterized physiologically by testing the effects of electron donors and electron acceptors on the dechlorinating activity. The dechlorinating activity was promoted with lactate, pyruvate, and hydrogen as electron donors but not with acetate. Electron acceptors, nitrate and sulphate, inhibited the dechlorinating activity competitively but not iron (III). The microbial group associated with the anaerobic dechlorination was characterized by the effect of specific inhibitors on the PCP dechlorination. Effects of specific metabolic inhibitors and antibiotics indicated the involvement of Gram-positive spore-forming bacteria with the PCP dechlorinating activity, which was represented as bacteria of phylum Firmicutes. The structure of the microbial community was characterized by fluorescence in situ hybridization, quinone profiling, and PCR-DGGE (denaturing gel gradient electrophoresis). The combined results indicated the predominance of Clostridium species of phylum Firmicutes in the microbial community. Desulfitobacterium spp. known as anaerobic Gram-positive spore-forming bacteria dechlorinating PCP were not detected by PCR using a

Electrochemically assisted photocatalysis using nanocrystalline semiconductor thin films

Energy Technology Data Exchange (ETDEWEB)

Vinodgopal, K [Department of Chemistry, Indiana University Northwest, Gary, Indiana (United States); Kamat, Prashant V [Notre Dame Radiation Laboratory, Notre Dame, Indiana (United States)

1995-08-01

The principle and usefulness of electrochemically assisted photocatalysis has been illustrated with the examples of 4-chlorophenol and Acid Orange 7 degradation in aqueous solutions. Thin nanocrystalline semiconductor films coated on a conducting glass surface when employed as a photoelectrode in an electrochemical cell are effective for degradation of organic contaminants. The degradation rate can be greatly improved even in the absence of oxygen by applying an anodic bias to the TiO{sub 2} film electrodes. A ten-fold enhancement in the degradation rate was observed when TiO{sub 2} particles were coupled with SnO{sub 2} nanocrystallites at an applied bias potential of 0.83 V versus SCE

Radiation-induced degradation of 4-chloroaniline in aqueous solution

International Nuclear Information System (INIS)

Sanchez, M.; Wolfger, H.; Getoff, N.

2002-01-01

The radiation-induced decomposition of 4-chloroaniline (4-ClA) was studied under steady-state conditions using aqueous solutions saturated with air, pure oxygen, N 2 O, argon and argon in the presence of t-Butanol. Using HPLC-method, the initial G-values of the substrate degradation as well as of a number of radiolytic products were determined. The formation of aminophenols, chlorophenols, aniline and phenol in addition to chloride, ammonia, formaldehyde and mixture of aldehydes as well as carboxylic acids was studied as a function of absorbed dose. Based on the experimental data, probable reaction mechanisms for the degradation of 4-ClA by γ-rays and the formation of the identified products are presented

Iron chloride catalysed PCDD/F-formation: Experiments and PCDD/F-signatures.

Science.gov (United States)

Zhang, Mengmei; Buekens, Alfons; Ma, Siyuan; Li, Xiaodong

2018-01-01

Iron chloride is often cited as catalyst of PCDD/F-formation, together with copper chloride. Conversely, iron chloride catalysis has been less studied during de novo tests. This paper presents such de novo test data, derived from model fly ash incorporating iron (III) chloride and established over a vast range of temperature and oxygen concentration in the gas phase. Both PCDD/F-output and its signature are extensively characterised, including homologue and congener profiles. For the first time, a complete isomer-specific analysis is systematically established, for all samples. Special attention is paid to the chlorophenols route PCDD/F, to the 2,3,7,8-substituted congeners, and to their relationship and antagonism. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanochemical Synthesis of Visible Light Sensitive Titanium Dioxide Photocatalyst

Directory of Open Access Journals (Sweden)

Jan Šubrt

2011-01-01

Full Text Available Phase transition of anatase nanoparticles into the phases TiO2-II and rutile under grinding was studied. The addition of ammonium carbamate to the reaction mixture inhibits the phase conversion and the cold welding of particles. The UV-visible absorption spectrum showed narrowing the band gap width after grinding with an ammonium carbamate additive resulting in shift of the light absorption of the ground sample towards the visible region. By EPR, intensive formation of OH• radical at irradiation of the sample with both UV (λ > 300 nm and visible (λ > 435 nm light was observed. High photocatalytic activity of the ground sample in visible light region was demonstrated also by measurement of kinetics of the photocatalytic decomposition of 4-chlorophenol.

Degradation of 4-chlorophenol in aqueous solution photoinduced by Fe(III)-citrate complex

Czech Academy of Sciences Publication Activity Database

Abida, O.; Kolář, Michal; Jirkovský, Jaromír; Mailhot, G.

2012-01-01

Roč. 11, č. 5 (2012), s. 794-802 ISSN 1474-905X Institutional support: RVO:61388955 Keywords : photochemistry * citric acid * hydroxyl radicals Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.923, year: 2012

Assessing the phototransformation of diclofenac, clofibric acid and naproxen in surface waters: Model predictions and comparison with field data.

Science.gov (United States)

Avetta, Paola; Fabbri, Debora; Minella, Marco; Brigante, Marcello; Maurino, Valter; Minero, Claudio; Pazzi, Marco; Vione, Davide

2016-11-15

Phototransformation is important for the fate in surface waters of the pharmaceuticals diclofenac (DIC) and naproxen (NAP) and for clofibric acid (CLO), a metabolite of the drug clofibrate. The goal of this paper is to provide an overview of the prevailing photochemical processes, which these compounds undergo in the different conditions found in freshwater environments. The modelled photochemical half-life times of NAP and DIC range from a few days to some months, depending on water conditions (chemistry and depth) and on the season. The model indicates that direct photolysis is the dominant degradation pathway of DIC and NAP in sunlit surface waters, and potentially toxic cyclic amides were detected as intermediates of DIC direct phototransformation. With modelled half-life times in the month-year range, CLO is predicted to be more photostable than DIC or NAP and to be degraded mainly by reaction with the • OH radical and with the triplet states of chromophoric dissolved organic matter ( 3 CDOM*). The CLO intermediates arising from these processes and detected in this study (hydroquinone and 4-chlorophenol) are, respectively, a chronic toxicant to aquatic organisms and a possible carcinogen for humans. Hydroquinone is formed with only ∼5% yield upon CLO triplet-sensitised transformation, but it is highly toxic for algae and crustaceans. In contrast, the formation yield of 4-chlorophenol reaches ∼50% upon triplet sensitisation and ∼10% by · OH reaction. The comparison of model predictions with field data from a previous study yielded a very good agreement in the case of DIC and, when using 4-carboxybenzophenone as proxy for triplet sensitisation by CDOM, a good agreement was found for CLO as well. In the case of NAP, the comparison with field data suggests that its direct photolysis quantum yield approaches or even falls below the lower range of literature values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Superoxide radical-mediated photocatalytic oxidation of phenolic compounds over Ag{sup +}/TiO{sub 2}: Influence of electron donating and withdrawing substituents

Energy Technology Data Exchange (ETDEWEB)

Xiao, Jiadong [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xie, Yongbing, E-mail: ybxie@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Han, Qingzhen [State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Cao, Hongbin [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Wang, Yujiao [Department of Chemical and Biomedical Engineering, University of Science and Technology Beijing (China); Nawaz, Faheem; Duan, Feng [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2016-03-05

Highlights: • A weak EWG benefited photocatalytic oxidation of phenols the most. • Phenolic compounds were dominantly oxidized by ·O{sub 2}{sup −}, rather than ·OH, {sup 1}O{sub 2} or h{sup +}. • ·O{sub 2}{sup −} preferred to nucleophilically attack EDG substituted phenols. • ·O{sub 2}{sup −} more likely electrophilically attacked EWG substituted phenols. • ·O{sub 2}{sup −} simultaneously nucleophilically and electrophilically assaulted p-chlorophenol. - Abstract: A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag{sup +}/TiO{sub 2} suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p-benzoquinone dramatically blocked the degradation, confirming superoxide radicals (·O{sub 2}{sup −}) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between ·O{sub 2}{sup −} and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of ·O{sub 2}{sup −} and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by ·O{sub 2}{sup −}, while ·O{sub 2}{sup −} preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by ·O{sub 2}{sup −} could simultaneously occur in p-chlorophenol degradation, consequently leading to its highest rate

Polydimethylsiloxane/covalent triazine frameworks coated stir bar sorptive extraction coupled with high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental water samples.

Science.gov (United States)

Zhong, Cheng; He, Man; Liao, Huaping; Chen, Beibei; Wang, Cheng; Hu, Bin

2016-04-08

In this work, covalent triazine frameworks (CTFs) were introduced in stir bar sorptive extraction (SBSE) and a novel polydimethylsiloxane(PDMS)/CTFs stir bar coating was prepared by sol-gel technique for the sorptive extraction of eight phenols (including phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-chloro-m-cresol and 2,4-dichlorophenol, 2,4,6-trichlorophenol) from environmental water samples followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The prepared PDMS/CTFs coated stir bar showed good preparation reproducibility with the relative standard deviations (RSDs) ranging from 3.5 to 5.7% (n=7) in one batch, and from 3.7 to 9.3% (n=7) among different batches. Several parameters affecting SBSE of eight target phenols including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.08-0.30 μg/L. The linear range was 0.25-500 μg/L for 2-nitrophenol, 0.5-500 μg/L for phenol, 2-chlorophenol, 4-nitrophenol as well as 2,4-dimethylphenol, and 1-500 μg/L for p-chloro-m-cresol, 2,4-dichlorophenol as well as 2,4,6-trichlorophenol, respectively. The intra-day relative standard deviations (RSDs) were in the range of 4.3-9.4% (n=7, c=2 μg/L) and the enrichment factors ranged from 64.9 to 145.6 fold (theoretical enrichment factor was 200-fold). Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/CTFs stir bar showed better extraction efficiency for target phenol compounds. The proposed method was successfully applied to the analysis of phenols in environmental water samples and good relative recoveries were obtained with the spiking level at 2, 10, 50 μg/L, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

Science.gov (United States)

Selvi, Canan; Nartop, Dilek

2012-09-01

New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

NIOSH Manual of Analytical Methods (third edition). Fourth supplement

Energy Technology Data Exchange (ETDEWEB)

1990-08-15

The NIOSH Manual of Analytical Methods, 3rd edition, was updated for the following chemicals: allyl-glycidyl-ether, 2-aminopyridine, aspartame, bromine, chlorine, n-butylamine, n-butyl-glycidyl-ether, carbon-dioxide, carbon-monoxide, chlorinated-camphene, chloroacetaldehyde, p-chlorophenol, crotonaldehyde, 1,1-dimethylhydrazine, dinitro-o-cresol, ethyl-acetate, ethyl-formate, ethylenimine, sodium-fluoride, hydrogen-fluoride, cryolite, sodium-hexafluoroaluminate, formic-acid, hexachlorobutadiene, hydrogen-cyanide, hydrogen-sulfide, isopropyl-acetate, isopropyl-ether, isopropyl-glycidyl-ether, lead, lead-oxide, maleic-anhydride, methyl-acetate, methyl-acrylate, methyl-tert-butyl ether, methyl-cellosolve-acetate, methylcyclohexanol, 4,4'-methylenedianiline, monomethylaniline, monomethylhydrazine, nitric-oxide, p-nitroaniline, phenyl-ether, phenyl-ether-biphenyl mixture, phenyl-glycidyl-ether, phenylhydrazine, phosphine, ronnel, sulfuryl-fluoride, talc, tributyl-phosphate, 1,1,2-trichloro-1,2,2-trifluoroethane, trimellitic-anhydride, triorthocresyl-phosphate, triphenyl-phosphate, and vinyl-acetate.

A pilot-scale study of the precursors leading to the formation of mixed bromo-chloro dioxins and furans

Energy Technology Data Exchange (ETDEWEB)

Lemieux, P.M.; Stewart, E.S. [US EPA, Research Triangle Park, NC (USA). Office of Research & Development

2004-02-01

Experiments were performed in a pilot-scale rotary kiln incinerator simulator, where a mixture of chlorinated and brominated surrogate waste was burned in the presence of injected flyash from a coal-fired utility boiler. Measurements were made of semivolatile products of incomplete combustion (PICs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs), and mixed bromo-chloro dibenzo-p-dioxins and furans (PXDDs/Fs). A statistical analysis of the data has been performed so that variability in the PCDDs/Fs can be accounted for by variation in the semivolatile PICs, particularly the chlorobenzenes (CBz) and chlorophenols (CPh). In addition, a statistical analysis was performed to investigate the variability of the PXDDs/Fs as a function of the concentrations of the semivolatile chlorinated, brominated, and mixed bromo-chloro organics.

Hemp (Cannabis sativa L.).

Science.gov (United States)

Feeney, Mistianne; Punja, Zamir K

2015-01-01

Hemp (Cannabis sativa L.) suspension culture cells were transformed with Agrobacterium tumefaciens strain EHA101 carrying the binary plasmid pNOV3635. The plasmid contains a phosphomannose isomerase (PMI) selectable marker gene. Cells transformed with PMI are capable of metabolizing the selective agent mannose, whereas cells not expressing the gene are incapable of using the carbon source and will stop growing. Callus masses proliferating on selection medium were screened for PMI expression using a chlorophenol red assay. Genomic DNA was extracted from putatively transformed callus lines, and the presence of the PMI gene was confirmed using PCR and Southern hybridization. Using this method, an average transformation frequency of 31.23% ± 0.14 was obtained for all transformation experiments, with a range of 15.1-55.3%.

Using Chlorella vulgaris to treat toxic excess sludge extract, and identification of its response mechanism by proteomics approach.

Science.gov (United States)

Wang, Lu; Wang, Hualin; Chen, Xiurong; Xu, Yan; Zhou, Tianjun; Wang, Xiaoxiao; Lu, Qian; Ruan, Roger

2018-04-01

Chlorella vulgaris was cultivated in varying proportions of toxic sludge extracts obtained from a sequencing batch reactor for treating synthetic wastewater containing chlorophenols. C. vulgaris could reduce the ecotoxicity from sludge extracts, and a positive correlation was noted between ecotoxicity removal and total organic carbon removal. In terms of cell density, the optimal proportion of sludge extracts required for the cultivation of C. vulgaris was lower than 50%. The correlation between protein content in per 10 6 algae and inhibition extent of ecotoxicity of the 5 groups on the day of inoculation (0.9182, p vulgaris produced proteins that involved in the stress response/redox system and energy metabolism/biosynthesis to respond to the toxic environment and some other proteins related to mixotrophic metabolism. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis and X-ray structure of the dysprosium(III complex derived from the ligand 5-chloro-1,3-diformyl-2-hydroxybenzene-bis-(2-hydroxybenzoylhydrazone [Dy2(C22H16ClN4O53](SCN 3.(H2O.(CH3OH

Directory of Open Access Journals (Sweden)

Aliou H. Barry

2003-12-01

Full Text Available The title compound [Dy2(C22H16ClN4O53](SCN 3.(H2O.(CH3OH has been synthesized and its crystal structure determined by single X-ray diffraction at room temperature. The two nine coordinated Dy(III are bound to three macromolecules ligand through the phenolic oxygens of the p-chlorophenol moieties, the nitrogen atoms and the carbonyl functions of the hydrazonic moieties. The phenolic oxygen atoms of the 2-hydroxybenzoyl groups are not bonded to the metal ions. In the bases of the coordination polyhedra the six Dy-N bonds are in the range 2.563(13-2.656(13 Å and the twelve Dy-O bonds are in the range 2.281(10-2.406(10 Å.

Conductometric Microbiosensors for Environmental Monitoring

Directory of Open Access Journals (Sweden)

Sergei V. Dzyadevych

2008-04-01

Full Text Available This review presents the principles of conductometric measurements in ionic media and the equivalent electrical circuits of different designs for conductometric measurements. These types of measurements were first applied for monitoring biocatalytic reactions. The use of conductometric microtransducers is then presented and detailed in the case of pollutant detection for environmental monitoring. Conductometric biosensors have advantages over other types of transducers: they can be produced through inexpensive thinfilm standard technology, no reference electrode is needed and differential mode measurements allow cancellation of a lot of interferences. The specifications obtained for the detection of different pesticides, herbicides and heavy metal ions, based on enzyme inhibition, are presented as well as those obtained for the detection of formaldehyde, 4- chlorophenol, nitrate and proteins as markers of dissolved organic carbon based on enzymatic microbiosensors.

Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

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Vorleak Chea

2014-10-01

Full Text Available This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR. The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1, consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2, whereas at the highest substrate concentration (500 mg·L−1, it was shown that the reaction was limited by the oxygen content.

Biochemical and physiological effects of phenols on human health

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Danuta Wojcieszyńska

2011-03-01

Full Text Available Introduction of phenol compounds into environment results from human activities.. Moreover plants produce polyphenols as by products of metabolism Their influence on human health is very important. It is observed, that polyphenols found in groceries are the most abundant dietary antioxidants, anti-inflammatory, anti allergic, antiarteriosclerotic and antitumour factors. Alkylphenols, chlorophenols, nitrophenols or biphenyls can be toxic for body systems and because of their similarity to ligands of steroid receptors they can influence the activity of endocrine system. Their appearance in organisms enhances the risk of developing type 2 diabetes mellitus, hypertension, dyslipidemia, cancer, problems with fertility. Moreover strong genotoxic activities of these compounds is observed. Because they influence human health in many different ways continuous monitoring of phenols content in environment seems to be very important.

[Microwave assisted UV electrodeless discharge lamp photochemical degradation of 4-chlorophenol in aquatic solutions].

Science.gov (United States)

Ai, Zhi-hui; Jiang, Jun-qing; Yang, Peng; Zhou, Tao; Lu, Xiao-hua

2004-07-01

A microwave assisted UV electrodeless discharge lamp system (MW/UV) was used for photo-degradation of 4CP simulated wastewater. In order to evaluate the degradation efficiency of 4CP, UV spectrophotometry and ion chromatography were used for determination of 4CP and Cl- respectively. The degradation rate in MW/UV system was higher than that in the UV system within 120min, which were 52.40% and 21.56% respectively. The degradation efficiency was improved by increasing pH value of the solution, aerating O2 gas, enhancing light intensity, or adding H2O2 oxidant. The degradation of 4CP under MW/UV accords with the first order kinetics equation.

Use of Low-cost Adsorbents to Chlorophenols and Organic Matter Removal of Petrochemical Wastewater

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Aretha Moreira de Oliveira

2013-11-01

Full Text Available The removal of 2,4 diclorophenol (2,4-DCF and 2,4,6 trichlorophenol (2,4,6 TCF present in  petrochemical wastewater was evaluated using low-cost adsorbents, such as chitin, chitosan and coconut shells. Batch studies showed that the absorption efficiency for 2,4 DCF and 2,4,6 TCF follow the order: chitosan > chitin > coconut shells. Langmuir and Freundlich models have been applied to experimental isotherms data, to better understand the adsorption mechanisms. Petrochemical wastewater treatment with fixed bed column system using chitinous adsorbents showed a removal of COD (75% , TOG (90% and turbidity (74-89%.

Simple colorimetric assay for dehalogenation reactivity of nanoscale zero-valent iron using 4-chlorophenol

DEFF Research Database (Denmark)

Hwang, Yuhoon; Mines, Paul D.; Jakobsen, Mogens Havsteen

2015-01-01

Despite the wide application of nanoscale zero valent iron (nZVI) for the treatment of a plethora of pollutants through reductive reactions, reactivity evaluation of nZVI towards dehalogenation has not been standardized. In this light, it was desired to develop a simple colorimetric assay...

14N NQR study of hydrogen bonded complexes of 1,4 diazabicyclo [2,2,2] octane (ted) with phenols and thiourea

Science.gov (United States)

Murgich, Juan; Magaly, Santana R.; Diaz, Olga E.

The 14N NQR spectra of H bonded complexes of 1,4 diazabicyclo [2,2,2] octane, also known as triethylenediamine (TED), with phenol (1:2), p-chlorophenol (1:2), p-nitrophenol (1:2), hydroquinone (1:1), resorcinol (1:1) and thiourea (1:2) were observed at 77 K. The 14N frequency shifts produced by the H bonds in the TED complexes were approximately two times larger than those found for similar complexes of Hexamethylenetetramine (HMT). Such change was explained by the effect on the remaining N atoms of the increase in the number of -CH 2- groups and the decrease in N atoms in passing from HMT to TED. From the above results it seems that the inductive effect plays an important role in the formation of H bonds in tertiary amines like HMT and TED.

Formation of secondary products in water purification. ; Toxicological evaluation of mutagenic chlorination by-products during drinking water treatment. Josui shori ni okeru fukuseiseibutsu. ; Josui shori ni okeru hen'i genseibusshitsu no dokusei hyoka

Energy Technology Data Exchange (ETDEWEB)

Nakamuro, K [Setsunan Univ., Osaka (Japan). Faculty of Pharmaceutical Sciences; Sayato, Y [Setsunan Univ., Osaka (Japan)

1993-12-10

The biological effects of acute toxicity, chronic toxicity, carcinogenicity, etc. of chlorination by-products detected in drinking water in Japan are discussed. The biological effects of representative chlorination by-products such as trihalomethane, haloacetic acid, haloaldehyde, haloacetonitrile, chlorophenol, chloropicrin, etc. as well as the evaluation of mutagenicity in drinking water purification process, for which Ames Salmonella/microsome assay is used for safety evaluation of drinking water, are discussed. The extent of the contribution of mutagenicity of chlorination disinfection by-products to the mutagenicity of drinking water is investigated. It must be admitted that biological evaluation of the safety of water quality is impossible currently by using only the known chemical substances contained in drinking water. The effects of chlorination and ozone treatment which are often applied to drinking water treatment are different each other. 58 refs., 1 fig., 4 tabs.

Illness associated with contamination of drinking water supplies with phenol

Energy Technology Data Exchange (ETDEWEB)

Jarvis, S.N.; Straube, R.C.; Williams, A.L.; Bartlett, C.L.

1985-06-15

In January 1984 the River Dee in north Wales was contaminated with phenol, with subsequent contamination of the tap water received by about two million consumers. A retrospective postal survey of 594 households was undertaken to determine whether consumption of this contaminated water was associated with illness. Subjects in areas that received contaminated water reported significantly more gastrointestinal illness than those in a nearby unexposed area (32.6% v 8.7%, p less than 0.00001) as well as reporting a higher incidence of any symptoms (43.6% v 18.4%, p less than 0.00001). Symptoms were consistent with phenol poisoning and bore a strong temporal relation to the pollution of the supply, but they developed at concentrations of phenols previously considered to be safe by the water authorities concerned. Chlorophenols produced during the treatment of water may have aggravated the problem.

Complete dechlorination of 2,4-dichlorophenol in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel composite electrode

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhirong, E-mail: zrsun@bjut.edu.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Wei, Xuefeng; Han, Yanbo; Tong, Shan [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Hu, Xiang, E-mail: huxiang99@163.com [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2013-01-15

Highlights: ► Pd/PPy-CTAB/foam-Ni electrode with high surface area and low Pd content was prepared. ► The composite electrode was applied to dechlorination of 2,4-DCP in aqueous solution. ► Complete dechlorination of 2,4-DCP was achieved with higher current efficiency. ► Removal efficiency kept 100% after 10 times dechlorination on the stable electrode. ► The electrochemically reductive activation energy was 25.8 kJ mol{sup −1} in this system. -- Abstract: The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5 mA and the dechlorination time of 50 min when the initial 2,4-DCP concentration was 100 mg L{sup −1}. The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused

Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

Energy Technology Data Exchange (ETDEWEB)

Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J. [Department of Materials Science and Engineering, NC State University, EB-1, Raleigh, North Carolina 27695-7907 (United States)

2013-06-21

We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO<111 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line c-YSZ<100>. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min{sup -1} for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies

Pellicular particles with spherical carbon cores and porous nanodiamond/polymer shells for reversed-phase HPLC.

Science.gov (United States)

Wiest, Landon A; Jensen, David S; Hung, Chuan-Hsi; Olsen, Rebecca E; Davis, Robert C; Vail, Michael A; Dadson, Andrew E; Nesterenko, Pavel N; Linford, Matthew R

2011-07-15

A new stationary phase for reversed-phase high performance liquid chromatography (RP HPLC) was created by coating spherical 3 μm carbon core particles in a layer-by-layer (LbL) fashion with poly(allylamine) (PAAm) and nanodiamond. Unfunctionalized core carbon particles were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and Raman spectroscopy. After LbL of PAAm and nanodiamond, which yields ca. 4 μm core-shell particles, the particles were simultaneously functionalized and cross-linked using a mixture of 1,2-epoxyoctadecane and 1,2,7,8-diepoxyoctane to obtain a mechanically stable C(18)/C(8) bonded outer layer. Core-shell particles were characterized by SEM, and their surface area, pore diameter, and volume were determined using the Brunauer-Emmett-Teller (BET) method. Short stainless steel columns (30 × 4.6 mm i.d.) were packed and the corresponding van Deemter plots obtained. The Supporting Information contains a MATLAB program used to fit the van Deemter data. The retentions of a suite of analytes were investigated on a conventional HPLC at various organic solvent compositions, pH values of mobile phases, including extreme pH values, and column temperatures. At 60 °C, a chromatogram of 2,6-diisopropylphenol showed 71,500 plates/m (N/m). Chromatograms obtained under acidic conditions (pH 2.7) of a mixture of acetaminophen, diazepam, and 2,6-diisopropylphenol and a mixture of phenol, 4-methylphenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol, and 1-tert-butyl-4-methylphenol are presented. Retention of amitriptyline, cholesterol, and diazinon at temperatures ranging from 35 to 80 °C and at pH 11.3 is reported. A series of five basic drugs was also separated at this pH. The stationary phase exhibits considerable hydrolytic stability at high pH (11.3) and even pH 13 over extended periods of time. An analysis run on a UHPLC with a "sandwich" injection

Influence of the particle size of activated mineral carbon on the phenol and chlorophenol adsorption

International Nuclear Information System (INIS)

Garcia M, A.

2001-01-01

Water pollution by phenolic compounds is a problem that requires a solution since these phenolic compounds are not completely biodegradable, they accumulate through the food chains and they are quite toxic when enter in contact with living organisms. In human beings, ingestion or contact of the skin with this type of compounds produces irritation and damages mainly to the liver and kidneys. In fact, the Environmental Protection Agency of the United States (EPA assigned nine phenolic compounds among the 275 most toxic substances in 1991. Phenols are found in wastewater from agriculture and industry, because phenolic compounds are used as pesticides and in diverse industrial activities. The treatment of this type of water is not simple because they are generally composed of a mixture of residuals with different chemical nature A useful method for the removal of phenols is the adsorption by activated carbon, since this material has a great surface area and it can be regenerated. The adsorption process depends, among other factors, on the activated carbon characteristics. When they are modified, their capacity to remove pollutants from the water changes. The effect of activated carbon particle size on the removal of phenolic compounds has not been completely studied. Therefore, the aim of this work was to determine the influence of the mineral activated carbon particle size on the phenol and 4-chloro phenol adsorption in aqueous solution, on adsorption column system. The results of the present work indicate that the mineral activated carbon particle size has a very important influence on the adsorption of phenol and 4-chloro phenol. When the particles were smaller, the retention quantities of phenol and 4-chloro phenol increased. This behavior was related to the particle characteristics of the mineral activated carbon such as surface area and pore volume, while other factors such as elementary composition of the activated carbon did not influence the adsorption process in an important way. Finally, when the particle size decreased, the saturation percentage decreased as well as the adsorption capacity increased for the studied phenolic compounds. (Author)

DETERMINATION OF CHLOROPHENOLS, NITROPHENOLS, AND METHYLPHENOLS IN GROUND-WATER SAMPLES USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Science.gov (United States)

A high performance liquid chromatography (HPLC) method was developed to quantitatively determine phenolic compounds and their isomers in aqueous samples. The HPLC method can analyze a mixture of 15 contaminants in the same analytical run with an analysis time of 25 minutes. The...

Determination of oxidation products in radiolysis of halophenols with pulse radiolysis, hplc, and ion chromatography

International Nuclear Information System (INIS)

Ye, M.; Schuler, R.H.

1990-01-01

This paper reports on hydroxyl radicals that react with halogen substituted phenols by several different ways. One is addition of OH radicals to the aromatic ring, which is followed by elimination of hydrogen halide, H 2 O or H - . The positions of OH radicals attack are dependent on the nature of the halogen which affects the electronic distribution in the ring. The oxidation of fluorophenols, chlorophenols and bromophenols with hydroxyl radicals in N 2 O saturated solution has been investigated with pulse radiolysis and γ-irradiation experiments. The intermediates of the reactions were studied by pulse radiolysis. The products created in the γ-irradiation of aqueous solutions of halophenols were analyzed by ion chromatography and high performance liquid chromatography (HPLC). With the combination of time-resolved and steady-state experiments a complete and detailed description of radiolytic oxidation of halophenols by hydroxyl radicals was obtained

Visible light assisted photodegradation of halocarbons on the dye modified TiO{sub 2} surface using visible light

Energy Technology Data Exchange (ETDEWEB)

Chatterjee, Debabrata; Dasgupta, Shimanti [Chemistry Section, Central Mechanical Engineering Research Institute, Durgapur 713209 (India); N Rao, Nageswar [Wastewater Technology Division, National Environmental Engineering Research Institute, Nagpur 400020 (India)

2006-05-05

Visible light assisted photodegradation of various halocarbons, viz. chloro-phenols, trichloroethylene, 1,2-dichloroethane and 1,4-dichlorobenzene, has been achieved on the surface of dye-modified TiO{sub 2} semiconductor. Thionine, eosinY, rhodamineB, methyleneblue, nileblueA and safranineO were used for the modification of TiO{sub 2} semiconductor photocatalyst. After 5h of irradiation with a 150W Xenon lamp, over 55-72% degradation of pollutants has been achieved. A working mechanism involving excitation of surface adsorbed dye, followed by charge injection into the TiO{sub 2} conduction band and formation of reactive {sup *}O{sub 2}{sup -}/{sup *}HO{sub 2} radicals, is proposed for the degradation of the enlisted organics to carbon dioxide. Efficacy of the photocatalytic system towards halocarbon degradation has been discussed in regard to excited state redox properties of the dyes selected for this study. Formation of {sup *}O{sub 2}{sup -} radical has been substantiated by using a chemiluminescent probe luminol. (author)

A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

Science.gov (United States)

Srujana, Dhegam; Sailu, Chinta

2018-04-01

The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

Synthesis, characterization and catalytic performance of ZnO-CeO2 nanoparticles in wet oxidation of wastewater containing chlorinated compounds

Science.gov (United States)

Anushree; Kumar, S.; Sharma, C.

2017-11-01

Here we report the catalytic property of ZnO-CeO2 nanoparticles towards oxidative degradation of organic pollutants present in industrial wastewater. The catalysts were prepared by co-precipitation method without using any surfactant. The physicochemical properties of catalysts were studied by XRD, Raman, XPS, N2-sorption, FE-SEM, TEM and EDX techniques. The characterization results confirmed the formation of porous ZnO-CeO2 nanocatalysts with high surface area, pore volume and oxygen vacancies. ZnO-CeO2 nanocatalysts exhibited appreciable efficiency in CWAO of industrial wastewater under mild conditions. The Ce40Zn60 catalyst was found to be most efficient with 72% color, 64% chemical oxygen demand (COD) and 63% total organic carbon (TOC) removal. Efficient removal of chlorophenolics (CHPs, 59%) and adsorbable organic halides (AOX, 54%) indicated the feasibility of using ZnO-CeO2 nanocatalysts in degradation of non-biodegradable and toxic chlorinated compounds.

Mixing Rules Formulation for a Kinetic Model of the Langmuir-Hinshelwood Semipredictive Type Applied to the Heterogeneous Photocatalytic Degradation of Multicomponent Mixtures

Directory of Open Access Journals (Sweden)

John Wilman Rodriguez-Acosta

2014-01-01

Full Text Available Mixing rules coupled to a semipredictive kinetic model of the Langmuir-Hinshelwood type were proposed to determine the behavior of the heterogeneous solar photodegradation with TiO2-P25 of multicomponent mixtures at pilot scale. The kinetic expressions were expressed in terms of the effective concentration of total organic carbon (xTOC. An expression was obtained in a generalized form which is a function of the mixing rules as a product of a global contribution of the reaction rate constant k′ and a mixing function fC. Kinetic parameters of the model were obtained using the Nelder and Mead (N-M algorithm. The kinetic model was validated with experimental data obtained from the degradation of binary mixtures of chlorinated compounds (DCA: dichloroacetic acid and 4-CP: 4-chlorophenol at different initial global concentration, using a CPC reactor at pilot scale. A simplex-lattice {2,3} design experiment was adopted to perform the runs.

Degrading Endocrine Disrupting Chemicals from Wastewater by TiO Photocatalysis: A Review

Directory of Open Access Journals (Sweden)

Jin-Chung Sin

2012-01-01

Full Text Available Widespread concerns continue to be raised about the impacts of exposure to chemical compounds with endocrine disrupting activities. To date, the percolation of endocrine disrupting chemical (EDC effluent into the aquatic system remains an intricate challenge abroad the nations. With the innovation of advanced oxidation processes (AOPs, there has been a consistent growing interest in this research field. Hence, the aim of this paper is to focus one such method within the AOPs, namely, heterogeneous photocatalysis and how it is used on the abatement of EDCs, phthalates, bisphenol A and chlorophenols in particular, using TiO2-based catalysts. Degradation mechanisms, pathways, and intermediate products of various EDCs for TiO2 photocatalysis are described in detail. The effect of key operational parameters on TiO2 photocatalytic degradation of various EDCs is then specifically covered. Finally, the future prospects together with the challenges for the TiO2 photocatalysis on EDCs degradation are summarized and discussed.

Assessment of PCDD/Fs levels in soil at a contaminated sawmill site in Sweden--a GIS and PCA approach to interpret the contamination pattern and distribution.

Science.gov (United States)

Henriksson, S; Hagberg, J; Bäckström, M; Persson, I; Lindström, G

2013-09-01

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) were analysed in soil from a Swedish sawmill site where chlorophenols (CPs) had been used more than 40 years ago. The most contaminated area at the site was the preservation subarea where the PCDD/F WHO2005-TEQ level was 3450 times higher than the current Swedish guideline value of 200 ng TEQ/kg soil for land for industrial use. It was also shown that a fire which destroyed the sawmill might have affected the congener distribution at the concerned areas. To get a broader picture of the contamination both GIS (spatial interpolation analysis) and multivariate data analysis (PCA) were applied to visualize and compare PCDD/F levels as well as congener distributions at different areas at the site. It is shown that GIS and PCA are powerful tools in decisions on future investigations, risk assessments and remediation of contaminated sites. Copyright © 2013 Elsevier Ltd. All rights reserved.

APPLICATION OF MAGNETIC CATALYSTS TO THE CATALYTIC WET PEROXIDE OXIDATION (CWPO OF INDUSTRIAL WASTEWATER CONTAINING NON BIODEGRADABLE ORGANIC POLLUTANTS

Directory of Open Access Journals (Sweden)

Macarena Munoz

2014-03-01

Full Text Available A new ferromagnetic -Al2O3-supported iron catalyst has been prepared and its activity and stability have been compared with those of a previous iron-based conventional catalyst and with the traditional homogeneous Fenton process in the oxidation of chlorophenols. The use of solid catalysts improved significantly the efficiency on the use of H2O2, achieving higher mineralization degrees. The magnetic catalyst led to significantly higher oxidation rates than the conventional one due to the presence of both Fe (II and Fe (III. On the other hand, the use of a catalyst with magnetic properties is of interest, since it allows rapid recovery after treatment using a magnetic field. Moreover, it showed a high stability with fairly low iron leaching (<1% upon CWPO runs. An additional clear advantage of this new catalyst is its easy separation and recovery from the reaction medium by applying an external magnetic field.

Microwave discharge electrodeless lamps (MDEL). Part IV. Novel self-ignition system incorporating metallic microwave condensing cones to activate MDELs in photochemical reactions.

Science.gov (United States)

Horikoshi, Satoshi; Tsuchida, Akihiro; Sakai, Hideki; Abe, Masahiko; Sato, Susumu; Serpone, Nick

2009-11-01

A metallic condensing cone that concentrates microwave radiation (equivalent to an optical lens) has been developed and used as part of a system to activate a microwave discharge electrodeless lamp (MDEL) in the oxidative treatment of wastewaters by aiding the novel self-ignition of the lamp on irradiation at low microwave power levels. This approach to self-ignition can potentially lead to considerable energy savings in such treatments. System performance was examined for the ignition power of microwaves of such MDEL devices in water, whose usefulness was assessed by investigating the photolytic transformation of aqueous solutions of representatives of three classes of contaminants: chlorinated phenols, herbicides and endocrine disruptors, specifically 4-chlorophenol (4-CP), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4,4'-isopropylidenediphenol (bisphenol-A; BPA), respectively, taken as model wastewaters in air-equilibrated, in oxygen-saturated and in TiO2-containing aqueous media. The results are discussed in terms of the dynamics of the photo-induced degradation processes.

Influence of He-Ne laser irradiation of soybean seeds on seed mycoflora, growth, nodulation, and resistance to Fusarium solani

International Nuclear Information System (INIS)

Ouf, S.A.; Abdel-Hady, N.F.

1999-01-01

Laser irradiation of soybean seeds for 3 min caused a clear reduction in the number of seed-borne fungi which became more pronounced as the irradiation time was extended. Pretreatment of the seeds with methylene blue, methyl red and carmine enhanced the effect of laser. Rhizoctonia solani, Alternaria tenuissima, Cercospora kikuchii and Colletotrichum truncatum were completely eliminated when the seeds were pretreated with a dye and irradiated for 10 min. Seed germination was stimulated on exposure of the seed to 1-min irradiation. Chlorophyll a, chlorophyll b and carotenoid content of developed plants differed, depending on the irradiation dose and dye treatment of the seeds. The number and dry mass of nodules were mostly greater (as compared to the corresponding control), when the seeds irradiated for 1 or 3 min were pretreated with methyl red, chlorophenol red, crystal violet and methylene blue. Irradiation of pre-sowing seeds greatly protected soybean stands against F. solani

Immobilization of Tyrosinase on (3-Aminopropyltriethoxysilane-Functionalized Carbon Felt-Based Flow-Through Detectors for Electrochemical Detection of Phenolic Compounds

Directory of Open Access Journals (Sweden)

Zheng Zhou

2017-07-01

Full Text Available Tyrosinase (TYR was covalently immobilized onto amino-functionalized carbon felt (CF surface via glutaraldehyde (GA. Prior to the TYR-immobilization, primary amino group was introduced to the CF surface by treatment with 3-aminopropyltriethoxysilane (APTES. The resulting TYR-immobilized CF was used as a working electrode unit of an electrochemical flow-through detector for mono- and di-phenolic compounds (i.e., catechol, p-cresol, phenol and p-chlorophenol. Additionally, flow injection peaks based on electroreduction of the enzymatically produced o-quinone species were detected at −0.05 V vs. Ag/AgCl. The resulting TYR/GA/APTES/CF biosensor responded well to all compounds tested with limits of detection range from 7.5 to 35 nmol−1 (based on three times S/N ratio. Moreover, such modified electrode exhibits good stability and reproducibility for catechol. No serious degradation of the peak current was found over 30 consecutive injections.

Environmental effect and fate of selected phenols in aquatic ecosystems using microcosm approaches

International Nuclear Information System (INIS)

Portier, R.J.; Chen, H.M.; Meyers, S.P.

1983-01-01

Microbiological studies, together with physicochemical analyses of selected industrial source phenols of environmental significance, were conducted in continuous flow and carbon metabolism microcosms to determine the behavior of these priority pollutants in soil and sediment-water systems typical of coastal wetlands. Phenols used included 4- nitrophenol, 2,4,6-trichlorophenol, 2-chlorophenol, and phenol. The organophosphate, 14 C-UL-Methyl Parathion, was used as a benchmark toxicant control while 14 C-Ring-Phenol was employed for all phenolic compound additions. Microbial diversity, ATP, and specific enzyme systems (i.e., phosphatase, dehydrogenase) were continuously monitored along with 14 CO 2 expiration and 14 C assimilation by the cellular component. Residual analysis of all microcosm tests employed procedures using combined gas chromatography/high-performance liquid chromatography. Statistical analyses were conducted of variations of testing criteria, along with a ranking profile of relative biotransformation and biodegradation potential. Data presented confirm the validity of microcosm approaches and related correlation analysis in toxic substance fate investigations. 17 references, 6 figures, 1 table

Detection of toxic compounds in real water samples using a conductometric tyrosinase biosensor

International Nuclear Information System (INIS)

Anh, Tuan Mai; Dzyadevych, Sergei V.; Prieur, Nicolas; Duc, Chien Nguyen; Pham, T.D.; Renault, Nicole Jaffrezic; Chovelon, Jean-Marc

2006-01-01

A conductometric tyrosinase biosensor for the detection of some toxic compounds including diuron, atrazine, and copper ions was developed. The work of this biosensor is based on the principle of change of conductivity of the enzyme membrane when tyrosinase either interacts with 4-chlorophenol substrate or is inhibited by pollutants. The different samples tested were solutions containing diuron, atrazine, copper, lead and zinc ions, mixtures of copper/atrazine or copper/diuron and real water samples coming from a Vietnamese river. In the last case, classical techniques such as GC-MS or atomic absorption spectrometry were used in order to estimate exact concentration of these species in real water samples. Results have shown that such a biosensor could be used as an early warning system for the detection of these pollutants, as no matrix effect coming from the real sample was observed and no synergetic or antagonist effects were found for the mixture of toxic compounds. In addition, results were coherent with the content of the tyrosinase inhibitors

Detection of toxic compounds in real water samples using a conductometric tyrosinase biosensor

Energy Technology Data Exchange (ETDEWEB)

Anh, Tuan Mai [Laboratoire d' Application de la Chimie a l' Environnement, UMR CNRS 5634, Universite Claude Bernard Lyon I, 43 Boulevard du 11 Nov. 1918, 69622 Villeurbanne Cedex (France); International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi, Vietnam (Viet Nam); Dzyadevych, Sergei V. [Laboratory of Biomolecular Electronics, Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, 150 Zabolotnogo Str., Kiev 03143 (Ukraine); Prieur, Nicolas [Institute of Natural Products Chemistry, Vietnam National Centre for Science and Technology, Hoang Quoc Viet Str., Hanoi, Vietnam (Viet Nam); Duc, Chien Nguyen [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi, Vietnam (Viet Nam); Pham, T.D. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi, Vietnam (Viet Nam); Renault, Nicole Jaffrezic [Ecole Centrale de Lyon, CEGELY, UMR CNRS 5005, 36 Avenue Guy de Collongue, 69134 Ecully Cedex (France); Chovelon, Jean-Marc [Laboratoire d' Application de la Chimie a l' Environnement, UMR CNRS 5634, Universite Claude Bernard Lyon I, 43 Boulevard du 11 Nov. 1918, 69622 Villeurbanne Cedex (France)]. E-mail: chovelon@univ-lyon1.fr

2006-03-15

A conductometric tyrosinase biosensor for the detection of some toxic compounds including diuron, atrazine, and copper ions was developed. The work of this biosensor is based on the principle of change of conductivity of the enzyme membrane when tyrosinase either interacts with 4-chlorophenol substrate or is inhibited by pollutants. The different samples tested were solutions containing diuron, atrazine, copper, lead and zinc ions, mixtures of copper/atrazine or copper/diuron and real water samples coming from a Vietnamese river. In the last case, classical techniques such as GC-MS or atomic absorption spectrometry were used in order to estimate exact concentration of these species in real water samples. Results have shown that such a biosensor could be used as an early warning system for the detection of these pollutants, as no matrix effect coming from the real sample was observed and no synergetic or antagonist effects were found for the mixture of toxic compounds. In addition, results were coherent with the content of the tyrosinase inhibitors.

No-core fiber-based highly sensitive optical fiber pH sensor.

Science.gov (United States)

Bhardwaj, Vanita; Pathak, Akhilesh Kumar; Singh, Vinod Kumar

2017-05-01

The present work describes the fabrication and characterization of an optical fiber pH sensor using a sol–gel technique. The sensing head configuration is incorporated using a short section of no-core fiber, coated with tetraethyl orthosilicate and spliced at the end of a single mode fiber with a bulge. Different types of indicators (bromophenol blue, cresol red, and chlorophenol red) were used to achieve a wide pH range from 2 to 13. High sensitivities of the fabricated device were found to be 1.02 and ? 0.93 ?? nm / pH for acidic and alkaline solutions, respectively. From the characterization results, it was noted that there is an impact of ionic strength and an effect of the temperature of liquid on the response characteristic, which is an advantage of the existing device over the other pH sensors. The fabricated sensor exhibited good reflection spectrum, indicating a blueshift in resonance wavelength for alkaline solutions and a redshift for acidic solutions.

Effects of gamma-radiation on the degradiation of substituted aromatics and of industrial waste water

International Nuclear Information System (INIS)

Gilbert, E.

1976-01-01

The radiation induced degradation of non-biodegradable organic compounds is demonstrated on chlorophenoles and 4-chlorocresole. The oxidation in aqueous solution (c=10 -3 mole/l) with air at doses up to one Mrad results in a complete dechlorination. The organic chlorine is converted to chloride. The influence of inorganic salts (c=10 -1 mole/l) on the irradiation of 2,4,6-trichlorophenole was investigated. The following organic compounds have been identified in the case of 4-chlorocresole as oxidation products: oxalic acid, formic acid, acetic acid, mesoxalic acid, glyoxal, mesoxalic acid semialdehyde. In addition to this, two types of industrial waste water were irradiated, one containing 2,4-dichlorophenole and 4-chlorocresole and another anthrachinonic dye. To oxidize 200 ppm of organic ompounds with a TOC and COD reduction of 50 - 70% 1 Mrad is needed. To eliminate 20 mg COD/1/0,2 Mrad on an average 20 mg oxygen have been consumed. (author)

Integrated ultrasonic/microbiological treatment of toxic and refractory pollutants

Energy Technology Data Exchange (ETDEWEB)

Tiehm, A. [Water Technology Center, Karlsruhe (Germany)

2002-07-01

The elimination of environmental pollutants by biodegradation in many cases represents an efficient and reliable method, e.g. in waste waster treatment, treatment of solid wastes, and in the remediation of contaminated soil. Nevertheless, there are situations where biological treatment alone does not result in a successful elimination of the target pollutants. For example, the presence of toxic compounds, an insufficient period of adaptation or a low bioavailability of the pollutants hinder a rapid biodegradation. Physico-chemical techniques, e.g. sonochemical degradation, provide an alternative to eliminate pollutants that are poorly biodegradable. It is the aim of this paper to demonstrate the potential of integrated ultrasound/biodegradation processes in the light of the underlying mechanisms. Optimisation of sonication is discussed with respect to ultrasound frequency and pH of the aqueous phase. Examplarily, two successful combinations of the integrated process are presented: (i) Application of ultrasound to reduce the toxicity of chlorophenols and (ii) ultrasonic irradiation to increase mass transfer and biodegradation of polyaromatic hydrocarbons. (orig.)

2-{1-[2-(Bis{2-[1-(5-chloro-2-hydroxyphenylethylideneamino]ethyl}aminoethyliminio]ethyl}-4-chlorophenolate toluene hemisolvate

Directory of Open Access Journals (Sweden)

Seik Weng Ng

2009-02-01

Full Text Available In the toluene hemisolvated tripodal tris(2-aminoethylamine Schiff base, C30H33Cl3N4O3·0.5C7H8, one of the three imino N atoms is protonated, forming a hydrogen bond with the O atom at an adjacent benzene ring. The other two imino N atoms act as hydrogen-bond acceptors from phenolate OH groups. The toluene solvent molecule is disordered about a centre of inversion.

Biodegradation of clofibric acid and identification of its metabolites.

Science.gov (United States)

Salgado, R; Oehmen, A; Carvalho, G; Noronha, J P; Reis, M A M

2012-11-30

Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration=2 mg L(-1)), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including α-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. α-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study. Copyright © 2012 Elsevier B.V. All rights reserved.

Anatase vs. rutile efficiency on the photocatalytic degradation of clofibric acid under near UV to visible irradiation.

Science.gov (United States)

Silva, Cláudia Gomes; Faria, Joaquim Luís

2009-05-01

Titanium dioxide (TiO(2)) powder, a semiconductor material typically used as a photocatalyst, is prepared following an acid-catalyzed sol-gel method starting from titanium isopropoxide. The xerogel calcination temperature is used to control surface and morphological properties of the material. Materials are extensively characterized by spectroscopic, micrographic and calorimetric techniques. The different TiO(2) catalysts are used in the visible-light-driven photocatalytic degradation of clofibric acid, a lipid regulator drug. The photoefficiency of TiO(2) catalysts, quantified in terms of kinetic rate constant, total organic carbon removal and initial quantum yield, increases with calcination temperature up to 673 K. A further increase in the calcination temperature leads to a decline in the photoefficiency of the catalysts, which is associated with the phase transformation from anatase to rutile concomitant with an increase in crystallite dimensions. The photochemical and photocatalytic oxidation of clofibric acid follows a pseudo-first order kinetic rate law. 4-Chlorophenol, isobutyric acid, hydroquinone, benzoquinone and 4-chlorocatechol are detected as main intermediates.

[Degradation of 2, 4-dichlorophenol in aqueous solution by ZVI/EDDS/air system].

Science.gov (United States)

Sun, Qian; Zhou, Hai-Yan; Cao, Meng-Hua; Wu, Lin-Na; Wang, Lin-Ling; Chen, Jing; Lu, Xiao-Hua

2012-11-01

A new oxidation system of Fenton-like system (ZVI/EDDS/Air) has been developed to degrade 2,4-chlorophenols (2,4-DCP) in aqueous solution. The influences of initial conditions, i. e., EDDS concentration, iron dosage, aeration rate, 2,4-DCP concentration and pH as well as reaction temperature on the degradation of 2,4-DCP were studied. The results demonstrated that this ZVI/EDDS/Air system was able to effectively degrade 2,4-DCP in aqueous solution, and the degradation of 2,4-DCP conforms to the pseudo-first-order reaction kinetics equation. Removal of above 99% 2,4-DCP was achieved in ZVI/EDDS/Air system at room temperature and pressure after 1 h reaction when the initial conditions were 2,4-DCP 100 mg x L(-1), EDDS 0.80 mmo x L(-1), ZVI 20 g x L(-1), aeration rate 2 L x (min x L)(-1). Compared with ZVI/EDTA/Air system, ZVI/EDDS/Air system showed higher efficiency in the degradation of 2,4-DCP at ambient circumstance and was more environmentally benign.

Solid/liquid extraction equilibria of phenolic compounds with trioctylphosphine oxide impregnated in polymeric membranes.

Science.gov (United States)

Praveen, Prashant; Loh, Kai-Chee

2016-06-01

Trioctylphosphine oxide based extractant impregnated membranes (EIM) were used for extraction of phenol and its methyl, hydroxyl and chloride substituted derivatives. The distribution coefficients of the phenols varied from 2 to 234, in the order of 1-napthol > p-chlorophenol > m-cresol > p-cresol > o-cresol > phenol > catechol > pyrogallol > hydroquinone, when initial phenols loadings was varied in 100-2000 mg/L. An extraction model, based on the law of mass action, was formulated to predict the equilibrium distribution of the phenols. The model was in excellent agreement (R(2) > 0.97) with the experimental results at low phenols concentrations ( 0.95), which signified high mass transfer resistance in the EIMs. Examination of the effects of ring substitution on equilibrium, and bivariate statistical analysis between the amounts of phenols extracted into the EIMs and factors affecting phenols interaction with TOPO, indicated the dominant role of hydrophobicity in equilibrium determination. These results improve understanding of the solid/liquid equilibrium process between phenols and the EIMs, and these will be useful in designing phenol recovery process from wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation and characterization of titania based nanowires

International Nuclear Information System (INIS)

Stengl, Vaclav; Bakardjieva, Snejana; Murafa, Natalie; Vecernikova, Eva; Subrt, Jan; Balek, Vladimir

2007-01-01

A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2-3 μm is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198 deg. C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350-1000 deg. C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength

Poly-3-hydroxybutyrate (PHB) production from alkylphenols, mono and poly-aromatic hydrocarbons using Bacillus sp. CYR1: A new strategy for wealth from waste.

Science.gov (United States)

Venkateswar Reddy, M; Mawatari, Yasuteru; Yajima, Yuka; Seki, Chigusa; Hoshino, Tamotsu; Chang, Young-Cheol

2015-09-01

In the present study five different types of alkylphenols, each of the two different types of mono and poly-aromatic hydrocarbons were selected for degradation, and conversion into poly-3-hydroxybutyrate (PHB) using the Bacillus sp. CYR1. Strain CYR1 showed growth with various toxic organic compounds. Degradation pattern of all the organic compounds at 100 mg/l concentration with or without addition of tween-80 were analyzed using high pressure liquid chromatography (HPLC). Strain CYR1 showed good removal of compounds in the presence of tween-80 within 3 days, but it took 6 days without addition of tween-80. Strain CYR1 showed highest PHB production with phenol (51 ± 5%), naphthalene (42 ± 4%), 4-chlorophenol (32 ± 3%) and 4-nonylphenol (29 ± 3%). The functional groups, structure, and thermal properties of the produced PHB were analyzed. These results denoted that the strain Bacillus sp. CYR1 can be used for conversion of different toxic compounds persistent in wastewaters into useable biological polyesters. Copyright © 2015 Elsevier Ltd. All rights reserved.

An efficient dye-sensitized BiOCl photocatalyst for air and water purification under visible light irradiation.

Science.gov (United States)

Li, Guisheng; Jiang, Bo; Xiao, Shuning; Lian, Zichao; Zhang, Dieqing; Yu, Jimmy C; Li, Hexing

2014-08-01

A photosensitized BiOCl catalyst was found to be effective for photocatalytic water purification and air remediation under visible light irradiation (λ > 420 nm). Prepared by a solvothermal method, the BiOCl crystals possessed a 3D hierarchical spherical structure with the highly active facets exposed. When sensitized by Rhodamine B (RhB), the photocatalyst system was more active than N-doped TiO2 for breaking down 4-chlorophenol (4-CP, 200 ppm) and nitric monoxide (NO, 500 ppb). The high activity could be attributed to the hierarchical structure (supplying feasible reaction tunnels for adsorption and transition of reactants or products) and the efficient exposure of the {001} facets. The former provides an enriched oxygen atom density that promotes adsorption of cationic dye RhB, and creates an oxygen vacancy state. The HO˙ and ˙O2(-) radicals produced from the injected electrons from the excited dye molecule (RhB*) into the conduction band of BiOCl were responsible for the excellent photocatalytic performance of the RhB-BiOCl system.

gamma-radiolysis and pulse radiolysis of aqueous 4-chloroanisole

DEFF Research Database (Denmark)

Quint, R.M.; Park, H.R.; Krajnik, P.

1996-01-01

of oxygen leads to its addition on the hydroxpcyclohexadienyl radicals, k(OH-adduct + O-2) = 3.2 x 10(8) dm(3) mol(-1) s(-1). In airfree solution the reaction of H-atom with the substrate, k(H + 4-ClAn) = 1.2 x 10(9) dm(3) mol(-1) s(-1), results in H-adducts which decay in bimolecular reactions, 2k = 8.2 x...... 10(8) dm(2) mol(-1) s(-1). The rate constant for the reaction of the solvated electrons has been determined to k (e(aq)(-) + 4-CIAn) = 2 x 10(9) dm(2) mol(-1) s(-1). The absorption spectra of H- and OH-adducts were measured in the range of 280-450 nm. The products analysed by HPLC after T......-radiolysis in dependence of dose (100-600 Gy) are given for N2O-, air-, oxygen- and argon saturated neutral aqueous solutions. In conditions favoring the OH radical oxidation 4-chlorophenol, 4-methoxyphenol, 5-chloro-2-methoxyphenol and 2-chloro-5-methoxyphenol were determined as final products. In the presence of Ar...

Recycling of agricultural solid waste, coir pith: Removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon

International Nuclear Information System (INIS)

Namasivayam, C.; Sangeetha, D.

2006-01-01

The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl 2 activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl 2 activated coir pith carbon is effective for the removal of toxic pollutants from water

Environmental Green Chemistry Applications of Nanoporous Carbons

Energy Technology Data Exchange (ETDEWEB)

Matos, J.; Garcia, A; Poon, P

2010-01-01

Influence of surface properties of nanoporous carbons on activity and selectivity during the photooxidation of 4-chlorophenol on UV-irradiated TiO{sub 2} was performed. Characterization by infrared spectroscopy, X-ray photoelectronic spectroscopy and X-ray absorption near edge structure spectroscopy confirm the presence of a contact interface between both solids and suggest the coordination of some functional organic groups of the carbon surface, mainly ethers and carboxylic acids, to metallic centre Ti{sup +4} in TiO{sub 2}. Changes in surface pH of carbons from basic to neutral or acid remarkably increase the production of 4-chlorocathecol by a factor of 22 on TiO{sub 2}-Carbon in comparison of TiO{sub 2} alone. A scheme of interaction between TiO{sub 2} and carbon is proposed to the increased photoactivity of TiO{sub 2} and a reaction mechanism for the different intermediate products detected is also proposed. Results showed that TiO{sub 2}-Carbon can be used as an alternative photocatalyst for environmental green chemistry and selective organic synthesis applications.

Disinfection of tertiary wastewater effluent prior to river discharge using peracetic acid; treatment efficiency and results on by-products formed in full scale tests.

Science.gov (United States)

Pedersen, Per Overgaard; Brodersen, Erling; Cecil, David

2013-01-01

This is an investigation of chemical disinfection, with peracetic acid (PAA), in a tertiary sand filter at a full scale activated sludge plant with nitrification/denitrification and P-removal. The reduction efficiency of Escherichia coli and intestinal enterococci in the sand filter is reported. E. coli log reductions of between 0.4 and 2.2 were found with contact times from 6 to 37 min and with dosing from 0 to 4.8 mg L(-1). The average log reduction was 1.3. The decomposition products, bromophenols, chlorophenols and formaldehyde and residual H2O2 were measured before and after the sand filter. The residual H2O2 concentration in the effluent was critical at short contact times and high dosages of PAA due to the discharge limit of 25 μg L(-1). The other three products could not be detected at 0.1 μg L(-1) levels. The chemical cost of PAA dosing is estimated to be 0.039 US$ m(-3) treated wastewater.

Solar driven production of toxic halogenated and nitroaromatic compounds in natural seawater

Energy Technology Data Exchange (ETDEWEB)

Calza, Paola [Dipartimento di Chimica Analitica, Universita di Torino, via P. Giuria 5, 10125 Torino (Italy)], E-mail: paola.calza@unito.it; Massolino, Cristina; Pelizzetti, Ezio; Minero, Claudio [Dipartimento di Chimica Analitica, Universita di Torino, via P. Giuria 5, 10125 Torino (Italy)

2008-07-15

Natural seawater (NSW) sampled in March and June 2007 in the Gulf of Trieste, Italy, has been spiked with phenol and irradiated in a device simulating solar light spectrum and intensity. Opposite to the case of artificial seawater, for which phenol is slightly degraded by direct photolysis, in NSW the phenol degradation mediated by natural photosensitizers occurs, forming several secondary pollutants, including hydroxyderivatives (1,4-benzoquinone, resorcinol), three chlorophenol isomers, 2,3-dichlorophenol, 2- and 4-bromophenol, 2- and 4-nitrophenol, and several condensed products (2 and 4-phenoxyphenol, 2,2'-, 4,4'- and 2,4-bisphenol). These compounds are toxic to bacteria and other living organisms. Ecotoxicologic effect has been evaluated by using the Vibrio Fischeri luminescent bacteria assay. This technique uses marine organisms, and it is therefore well suited for the study on marine samples. A correlation exists between the intermediates evolution and the toxicity profile, as the largest toxicity is observed when compounds with the lower EC50 (halophenols, phenoxyphenols) are formed at higher concentration.

Ochratoxin A: General Overview and Actual Molecular Status

International Nuclear Information System (INIS)

El Khoury, A.; Atoui, A.

2010-01-01

Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium fungi that structurally consists of a para-chlorophenolic group containing a dihydroisocoumarin moiety that is amide-linked to L-phenylalanine. OTA is detected worldwide in various food and feed sources. Studies show that this molecule can have several toxicological effects such as nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic. A role in the etiology of Balkan endemic nephropathy and its association to urinary tract tumors has been also proved. In this review, we will explore the general aspect of OTA: physico-chemical properties, toxicological profile, OTA producing fungi, contaminated food, regulation, legislation and analytical methods. Due to lack of sufficient information related to the molecular background, this paper will discuss in detail the recent advances in molecular biology of OTA biosynthesis, based on information and on new data about identification and characterization of ochratoxin biosynthetic genes in both Penicillium and Aspergillus species. This review will also cover the development of the molecular methods for the detection and quantification of OTA producing fungi in various foodstuffs. (author)

Solar driven production of toxic halogenated and nitroaromatic compounds in natural seawater

International Nuclear Information System (INIS)

Calza, Paola; Massolino, Cristina; Pelizzetti, Ezio; Minero, Claudio

2008-01-01

Natural seawater (NSW) sampled in March and June 2007 in the Gulf of Trieste, Italy, has been spiked with phenol and irradiated in a device simulating solar light spectrum and intensity. Opposite to the case of artificial seawater, for which phenol is slightly degraded by direct photolysis, in NSW the phenol degradation mediated by natural photosensitizers occurs, forming several secondary pollutants, including hydroxyderivatives (1,4-benzoquinone, resorcinol), three chlorophenol isomers, 2,3-dichlorophenol, 2- and 4-bromophenol, 2- and 4-nitrophenol, and several condensed products (2 and 4-phenoxyphenol, 2,2'-, 4,4'- and 2,4-bisphenol). These compounds are toxic to bacteria and other living organisms. Ecotoxicologic effect has been evaluated by using the Vibrio Fischeri luminescent bacteria assay. This technique uses marine organisms, and it is therefore well suited for the study on marine samples. A correlation exists between the intermediates evolution and the toxicity profile, as the largest toxicity is observed when compounds with the lower EC50 (halophenols, phenoxyphenols) are formed at higher concentration

CHLOROBENZENES, CHLOROPHENOLS, PAHS AND LOW CHLORINATED DIOXIN/FURAN AS POST-BOILER TOXICITY INDICATORS IN MUNICIPAL SOLID WASTE INCINERATORS

Science.gov (United States)

Numerous research studies have been conducted to establish indicator compounds for fast and less costly predictive monitoring of polychlorinated dibenzo-p-dioxin and furan (PCDD/F) toxic equivalent concentrations (TEQs). Many studies have shown that chlorobenzenes and chlorophen...

Leaching of chloride, sulphate, heavy metals, dissolved organic carbon and phenolic organic pesticides from contaminated concrete.

Science.gov (United States)

Van Praagh, M; Modin, H

2016-10-01

Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH>12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

Directory of Open Access Journals (Sweden)

Junjie Qian

2012-01-01

Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

A comparative study on the radiation induced degradation of chlorinated organics and water

International Nuclear Information System (INIS)

Bekboelet, M.; Balcioglu, A.I.; Getoff, N.

1998-01-01

Complete text of publication follows. Radiation induced degradation of chlorinated benzaldehydes has been studied by the application of UV-photolysis, UV-assisted catalytic oxidation and gamma radiolysis processes. The degradation was followed in terms of the substrate removal and formation of the decomposition products such as chloride and formaldehyde. Formation of the acidic compounds were also determined by the pH decrease during irradiation periods. The below given table summarizes the obtained results in terms of photochemical G (G PH )values. The main idea of this paper was to evaluate the applied processes in relation to the end products rather and to compare the efficiency of the methods. Besides, chloride and formaldehyde formation, the substrate degradation and formation of the stable end products, were followed by HPLC analyses. Hydroxylated parent compounds chlorophenols, benzaldehyde were also detected. Formation of muconic acid through ring opening as well as the formation of lower molecular weight organic acids by decomposition such as oxalic, citric, tartaric and formic acids were observed with respect the applied oxidation process. Depending on the formed stable end products and the related probable reaction mechanisms, isomeric positions were found to be selective toward oxidative degradation

Iron(III) phthalocyanine supported on a spongin scaffold as an advanced photocatalyst in a highly efficient removal process of halophenols and bisphenol A.

Science.gov (United States)

Norman, Małgorzata; Żółtowska-Aksamitowska, Sonia; Zgoła-Grześkowiak, Agnieszka; Ehrlich, Hermann; Jesionowski, Teofil

2018-04-05

This study investigated for the first time the degradation of phenol, chlorophenol, fluorophenol and bisphenol A (BPA) by the novel iron phthalocyanine/spongin hybrid material under various process conditions: hydrogen peroxide and UV irradiation. The heterogeneous catalyst, iron phthalocyanine/spongin (SFe), was produced by an adsorption process. The product obtained was investigated by a variety of spectroscopic techniques - X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and carbon-13 nuclear magnetic resonance ( 13 C NMR) - as well as elemental and thermal analysis. The study confirmed the stable immobilization of the dye on the biopolymer. The results demonstrate that the degradation of phenols and BPA followed pseudo-second-order kinetics under different experimental conditions. The synergy of SFe, H 2 O 2 and UV was found to produce a significant increase in the removal efficiency and resulted in complete removal of contaminants in a short time of 1 h. The reaction products were identified by high-performance liquid chromatography/mass spectrometry (HPLC-MS) and possible degradation pathways were proposed, featuring a series of steps including cleavage of CC bonds and oxidation. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural, antimicrobial and computational characterization of 1-benzoyl-3-(5-chloro-2-hydroxyphenyl)thiourea.

Science.gov (United States)

Atiş, Murat; Karipcin, Fatma; Sarıboğa, Bahtiyar; Taş, Murat; Çelik, Hasan

2012-12-01

A new thiourea derivative, 1-benzoyl-3-(5-chloro-2-hydroxyphenyl)thiourea (bcht) has been synthesized from the reaction of 2-amino-4-chlorophenol with benzoyl isothiocyanate. The title compound has been characterized by elemental analyses, FT-IR, (13)C, (1)H NMR spectroscopy and the single crystal X-ray diffraction analysis. The structure of bcht derived from X-ray diffraction of a single crystal has been presented. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method using 6-311++G(d,p) basis set. The complete assignments of all vibrational modes were performed on the basis of the total energy distributions (TED). Isotropic chemical shifts ((13)C NMR and (1)H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. Theoretical calculations of bond parameters, harmonic vibration frequencies and nuclear magnetic resonance are in good agreement with experimental results. The UV absorption spectra of the compound that dissolved in ACN and MeOH were recorded. Bcht was also screened for antimicrobial activity against pathogenic bacteria and fungi. Copyright © 2012 Elsevier B.V. All rights reserved.

Radiolytic degradation and toxicity changes in {gamma}-irradiated solutions of 2,4-dichlorophenol

Energy Technology Data Exchange (ETDEWEB)

Trojanowicz, M. E-mail: trojan@chem.uw.edu.pl; Drzewicz, P.; Panta, P.; Gluszewski, W.; Nalcz-Jawecki, G.; Sawicki, J.; Sampa, M.H.O.; Oikawa, H.; Borrely, S.I.; Czaplicka, M.; Szewczynska, M

2002-11-01

Preliminary investigations of a petroleum industry wastes with high concentrations of phenols and chlorophenols have shown that irradiation with electron beam results in the efficient destruction of specific organic compounds. In this study the degradation of 2,4-dichlorophenol (2,4-DCP) was studied using a {sup 60}Co gamma source. The determination of reaction by-products was carried out with HPLC, ion chromatography with various detectors, GC/MS and total organic carbon analyzer. The toxicity was measured with bioluminescence test Microtox[reg]. Studies of products of 2,4-DCP radiolysis at initial concentration level 20-50 mg/l have shown that with increased radiation dose degradation proceeds with a stepwise dehalogenation, through the formation of dihydroxybenzenes followed by the formation of non-aromatic carboxylic acids. The transient formation of dihydroxybenzenes resulted in an increase in toxicity at low doses up to 1 kGy. Even at a dose of 20 kGy, not more than about 20% mineralization was observed. The efficiency and mechanism of 2,4-DCP degradation is affected by the presence of scavengers of hydroxyl radical and hydrated electrons such as nitrate or bicarbonate.

Sequestration of a fluorinated analog of 2,4-dichlorophenol and metabolic products by L. minor as evidenced by 19F NMR

International Nuclear Information System (INIS)

Tront, Jacqueline M.; Saunders, F. Michael

2007-01-01

Fate of halogenated phenols in plants was investigated using nuclear magnetic resonance (NMR) to identify and quantify contaminants and their metabolites. Metabolites of 4-chloro-2-fluorophenol (4-Cl-2-FP), as well as the parent compound, were detected in acetonitrile extracts using 19 F NMR after various exposure periods. Several fluorinated metabolites with chemical shifts ∼3.5 ppm from the parent compound were present in plant extracts. Metabolites isolated in extracts were tentatively identified as fluorinated-chlorophenol conjugates through examination of signal-splitting patterns and relative chemical shifts. Signal intensity was used to quantify contaminant and metabolite accumulation within plant tissues. The quantity of 4-Cl-2-F metabolites increased with time and mass balance closures of 90-110% were achieved. In addition, solid phase 19 F NMR was used to identify 4-Cl-2-FP which was chemically bound to plant material. This work used 19 F NMR for developing a time series description of contaminant accumulation and transformation in aquatic plant systems. - The aquatic plant L. minor accumulates, sequesters and binds 4-chloro-2-fluorophenol and its metabolites, as was demonstrated using 19 F-NMR

A Simple Method for the Simultaneous Determination of Pharmaceuticals and Personal Care Products in River Sediment by Ultrasound-Assisted Extraction Followed by Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry.

Science.gov (United States)

Díaz, Alejandro; Peña-Alvarez, Araceli

2017-10-01

A simple method was developed using ultrasound-assisted extraction (UAE) combined with solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of eight different pharmaceuticals and personal care products (PPCPs) (ibuprofen, 2-benzyl-4-chlorophenol, naproxen, triclosan, ketoprofen, diclofenac, bisphenol A and estrone) in river sediment. UAE conditions were optimized involving extraction variables such as extraction solvent, extraction time, sample amount, extraction temperature, pH and salt addition. A 100 mg of sediment was extracted by optimized UAE process using 7 mL deionized water (pH 3) + 1% methanol as solvent, room temperature and 1 min extraction at 70% of amplitude. A 5 mL of supernatant was subsequently extracted by SPME; the extracted analytes were derivatized on fiber in head-space mode with N-methyl-N-(tertbutyldimethylsilyl) trifluoroacetamide and then analyzed by GC-MS. The developed method was evaluated by testing: precision (CV 0.98), recoveries (56-108%), limits of detection (simple and environmentally friendly, and provides straightforward analyses of these trace organic pollutants in sediment samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Emission of Polychlorinated Dibenzo-p-Dioxins (PCDDs and Polychlorinated Dibenzofurans (PCDFs from Underfiring System of Coke Oven Battery

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Rafał Bigda

2017-11-01

Full Text Available A coke oven battery is not considered as a significant source of PCDDs/PCDFs emissions; however, due to small amounts of chlorine in coal dioxins, dibenzofurans may be formed. The paper presents the attempts to determine the level of emission of PCDDs/PCDFs from the COB underfiring system and to confront the obtained results with the calculations based on the mass balance of chlorine in the coking process and reactions of both chlorophenols formation and PCDDs and PCDFs formation from mono- and polychlorophenols. There were PCDDs/PCDFs concentrations measured in flue gases from the underfiring system of two COBs at a Polish coking plant. The measurements included both an old and a new battery. The obtained concentrations of PCDDs/PCDFs were lower than reported in the literature (0.5-1.7 ng I-TEQ/tcoke, while the results for old COB were on average 3 times higher than for the new one. It was found that PCDD/F emission from COB underfiring system is insignificant and that PCDDs/PCDFs formation during coal coking should consider the mechanisms of their formation from mono- and polychlorophenols, as well as the influence of process parameters on the synthesis.

Preparation, spectroscopic studies and X-ray structure of homobinuclear lanthanide(III complexes derived from 2,6-diformyl-4-chlorophénol-bis-(2’-hydroxy-benzoylhydrazone

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Pepe Marcel Haba

2006-06-01

Full Text Available Reaction of the 2,6-diformyl-4-chlorophenol-bis-(2'-hydroxy-benzoylhydrazone with Ln(NO33.nH2O (n = 5 or 6 and Ln = Y, La, Ce, Pr, Nd, Sm, Gd, Dy, Er and Yb produces homobinuclear complexes. These complexes have been characterized by analysis, molar conductance, magnetic measurements, infrared spectral studies and X-ray diffraction. The analytical data showed 1:3 (metal:ligand stoichiometry. Molar conductance measurements in dmf indicate 1:3 electrolytes in all cases. Magnetic moment values are close proximity of the Van Vleck values. IR studies suggest the coordination of the ligand is through the azomethine, the phenolic oxygen atom and the carbonyl oxygen of the hydrazonic moiety. The nitrate ion is also found to be ionic in all the complexes. An X-ray structure determination of [C66H48N12O15Cl3Er2]Cl2NO3.5H2O confirms the conclusion from the spectroscopic studies and show that the erbium is at the centre of a tricapped trigonal prism with coordination number nine. In all the complexes the lanthanide ions have substantially similar coordination.

Appetite for danger - genetic potential for PCP degradation at historically polluted groundwater sites

Science.gov (United States)

Mikkonen, Anu; Yläranta, Kati; Tiirola, Marja; Romantschuk, Martin; Sinkkonen, Aki

2016-04-01

Pentachlorophenol (PCP) is a priority pollutant of exclusively anthropogenic origin. Formerly used commonly in timber preservatives, PCP has persisted at polluted groundwater sites decades after its use was banned, typically as the last detectable contaminant component. Notorious for its toxicity and poor biodegradability, little is known about the genetic potential and pathways for PCP degradation in the environment. The only fully characterized mineralization pathway is initiated by the enzyme coded by chromosomal pcpB gene, previously detected in PCP degrading Sphingomonadaceae bacteria isolated at two continents. However, there is no information about the abundance or diversity of any PCP degradation related gene at contaminated sites in situ. Our aim was to assess whether pcpB and/or sphingomonads seem to play a role in in situ degradation of PCP, by studying whether pcpB i) is detectable at chlorophenol-polluted groundwater sediments, ii) responds to PCP concentration changes, and iii) shows correlation with the abundance of sphingomonads or a specific sphingomonad genus. Novel protocols for quantification and profiling of pcpB, with primers covering full known diversity, were developed and tested at two sites in Finland with well-documented long-term chlorophenol contamination history: Kärkölä and Pursiala. High throughput sequencing complemented characterization of the total bacterial community and pcpB gene pool. The relative abundance of pcpB in bacterial community was associated with spatial variability in groundwater PCP concentration in Pursiala, and with temporal differences in groundwater PCP concentration in Kärkölä. T-RFLP fingerprinting results indicated and Ion Torrent PGM and Sanger sequencing confirmed the presence of a single phylotype of pcpB at both geographically distant, historically contaminated sites, matching the one detected previously in Canadian bioreactor clones and Kärkölä bioreactor isolates. Sphingomonad abundance

Biodegradation of clofibric acid and identification of its metabolites

International Nuclear Information System (INIS)

Salgado, R.; Oehmen, A.; Carvalho, G.; Noronha, J.P.; Reis, M.A.M.

2012-01-01

Graphical abstract: Metabolites produced during clofibric acid biodegradation. Highlights: ► Clofibric acid is biodegradable. ► Mainly heterotrophic bacteria degraded the clofibric acid. ► Metabolites of clofibric acid biodegradation were identified. ► The metabolic pathway of clofibric acid biodegradation is proposed. - Abstract: Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration = 2 mg L −1 ), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including α-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. α-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study.

Ag2WO4 nanorods decorated with AgI nanoparticles: Novel and efficient visible-light-driven photocatalysts for the degradation of water pollutants

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Shijie Li

2018-04-01

Full Text Available To develop efficient and stable visible-light-driven (VLD photocatalysts for pollutant degradation, we synthesized novel heterojunction photocatalysts comprised of AgI nanoparticle-decorated Ag2WO4 nanorods via a facile method. Various characterization techniques, including XRD, SEM, TEM, EDX, and UV–vis DRS were used to investigate the morphology and optical properties of the as-prepared AgI/Ag2WO4 catalyst. With AgI acting as the cocatalyst, the resulting AgI/Ag2WO4 heterostructure shows excellent performance in degrading toxic, stable pollutants such as rhodamine B (RhB, methyl orange (MO and para-chlorophenol (4-CP. The high performance is attributed to the enhanced visible-light absorption properties and the promoted separation efficiency of charge carriers through the formation of the heterojunction between AgI and Ag2WO4. Additionally, AgI/Ag2WO4 exhibits durable stability. The active species trapping experiment reveals that active species (O2•− and h+ dominantly contribute to RhB degradation. The AgI/Ag2WO4 heterojunction photocatalyst characterized in this work holds great potential for remedying environmental issues due to its simple preparation method and excellent photocatalytic performance.

Experiments on the VERONA test facility on formation and decomposition of polyhalogenated dioxins and furans and other organic halogen compounds in the combustion process; Untersuchungen an der Technikumsanlage VERONA zur Bildung und zum Abbau von polyhalogenierten Dioxinen und Furanen und anderen Organohalogenverbindungen in Verbrennungsprozessen

Energy Technology Data Exchange (ETDEWEB)

Schueler, D.

2002-09-01

The study examines measures to reduce dioxin formation in thermal waste treatment. The VERONA pilot plant (VErbrennungsanlage mit feststehendem ROst und getrennter NAchbrennkammer - incineration plant with stationary grate and separate post-combustion chamber) was developed to carry out practical experiments. The experiments were conducted using wood and propane as basic combustible materials and with controlled dosage of various bromine-, chlorine- and copper-containing compounds. The behaviour of the following compounds was studied in the combustion chamber, after the post-combustion chamber and after the heat exchanger: PCPh, PBrPh, PCBz, PBrBz, PCDD/F and PBDD/F. Experiments involving the variation of various primary measures (moisture content of combustible material, air supply, temperature in the combustion chamber, quality of post-combustion, quantities and structures of halogen compounds) have shown that the quality of post-combustion plays a much greater role than the other measures. For this reason, a search was launched for indicators which can be measured readily and by means of which the quality of post-combustion in terms of organohalide decomposition can be evaluated, and which correlate closely with the dioxin concentrations after the heat exchanger. It became apparent that the congeners of the chlorophenols and of the chlorobenzenes, measured in various incineration stages, are not suited, nor is the CO content. (orig.)

Activated carbon electrodes: electrochemical oxidation coupled with desalination for wastewater treatment.

Science.gov (United States)

Duan, Feng; Li, Yuping; Cao, Hongbin; Wang, Yi; Crittenden, John C; Zhang, Yi

2015-04-01

The wastewater usually contains low-concentration organic pollutants and some inorganic salts after biological treatment. In the present work, the possibility of simultaneous removal of them by combining electrochemical oxidation and electrosorption was investigated. Phenol and sodium chloride were chosen as representative of organic pollutants and inorganic salts and a pair of activated carbon plate electrodes were used as anode and cathode. Some important working conditions such as oxygen concentration, applied potential and temperature were evaluated to reach both efficient phenol removal and desalination. Under optimized 2.0 V of applied potential, 38°C of temperature, and 500 mL min(-1) of oxygen flow, over 90% of phenol, 60% of TOC and 20% of salinity were removed during 300 min of electrolysis time. Phenol was removed by both adsorption and electrochemical oxidation, which may proceed directly or indirectly by chlorine and hypochlorite oxidation. Chlorophenols were detected as degradation intermediates, but they were finally transformed to carboxylic acids. Desalination was possibly attributed to electrosorption of ions in the pores of activated carbon electrodes. The charging/regeneration cycling experiment showed good stability of the electrodes. This provides a new strategy for wastewater treatment and recycling. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis of Phase Pure Hexagonal YFeO3 Perovskite as Efficient Visible Light Active Photocatalyst

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Mohammed Ismael

2017-11-01

Full Text Available Hexagonal perovskite YFeO3 was synthesized by a complex-assisted sol-gel technique allowing crystallization at calcination temperatures below 700 °C. As determined by diffuse reflectance spectroscopy (DRS and Tauc plots, the hexagonal YFeO3 exhibits a lower optical band gap (1.81 eV than the orthorhombic structure (about 2.1 eV or even higher being typically obtained at elevated temperatures (>700 °C, and thus enables higher visible light photocatalysis activity. Structure and morphology of the synthesized YFeO3 perovskites were analyzed by powder X-ray diffraction (XRD and nitrogen adsorption, proving that significantly smaller crystallite sizes and higher surface areas are obtained for YFeO3 with a hexagonal phase. The photocatalytic activity of the different YFeO3 phases was deduced via the degradation of the model pollutants methyl orange and 4-chlorophenol. Experiments under illumination with light of different wavelengths, in the presence of different trapping elements, as well as photoelectrochemical tests allow conclusions regarding band positions of YFeO3 and the photocatalytic degradation mechanism. X-ray photoelectron spectroscopy indicates that a very thin layer of Y2O3 might support the photocatalysis by improving the separation of photogenerated charge carriers.

A comprehensive strategy for identifying long-distance mobile peptides in xylem sap.

Science.gov (United States)

Okamoto, Satoru; Suzuki, Takamasa; Kawaguchi, Masayoshi; Higashiyama, Tetsuya; Matsubayashi, Yoshikatsu

2015-11-01

There is a growing awareness that secreted pemediate organ-to-organ communication in higher plants. Xylem sap peptidomics is an effective but challenging approach for identifying long-distance mobile peptides. In this study we developed a simple, gel-free purification system that combines o-chlorophenol extraction with HPLC separation. Using this system, we successfully identified seven oligopeptides from soybean xylem sap exudate that had one or more post-transcriptional modifications: glycosylation, sulfation and/or hydroxylation. RNA sequencing and quantitative PCR analyses showed that the peptide-encoding genes are expressed in multiple tissues. We further analyzed the long-distance translocation of four of the seven peptides using gene-encoding peptides with single amino acid substitutions, and identified these four peptides as potential root-to-shoot mobile oligopeptides. Promoter-GUS analysis showed that all four peptide-encoding genes were expressed in the inner tissues of the root endodermis. Moreover, we found that some of these peptide-encoding genes responded to biotic and/or abiotic factors. These results indicate that our purification system provides a comprehensive approach for effectively identifying endogenous small peptides and reinforce the concept that higher plants employ various peptides in root-to-shoot signaling. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Species-specific accumulation of dioxin related compounds in cetaceans collected from Japanese coastal waters

Energy Technology Data Exchange (ETDEWEB)

Kajiwara, N.; Watanabe, M.; Tanabe, S. [Center for Marine Environmental Studies (CMES), Ehime Univ. (Japan); Amano, M. [Ocean Research Inst., Univ. of Tokyo, Iwate (Japan); Yamada, T. [National Science Museum, Tokyo (Japan)

2004-09-15

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are extremely hazardous and persistent chemicals identified as contaminants in chlorophenols, herbicides, fly ash and other incineration products. Dioxin-like PCBs including non- and mono-ortho coplanar PCBs are referred to as dioxin related compounds and are evaluated on par with PCDD/Fs in environmental risks since they have a high toxicity, similar to that of PCDD/Fs. These congeners have a range of physicochemical characteristics, which profoundly affect their persistence, environmental distribution, and bioaccumulation in aquatic food chains. Fish-eating wildlife such as marine mammals are particularly vulnerable to such contamination given their long lives, high trophic level, relative inability to metabolize many persistent organic pollutants (POPs), and the biomagnification of these contaminants in aquatic food chains. However, most studies dealing with PCDDs and PCDFs in marine mammals have been carried out on pinnipeds, and data on PCDD/Fs levels in cetaceans are scarce. The present study is aimed at understanding the recent pattern of contamination by dioxin related compounds including non- and mono-ortho coplanar PCBs and PCDD/Fs in three cetacean species collected from Japanese coastal waters during 1998-2001, and also to discuss the factors determining the accumulation.

Comparison of AOPs Efficiencies on Phenolic Compounds Degradation

Directory of Open Access Journals (Sweden)

Lourdes Hurtado

2016-01-01

Full Text Available In this work, a comparison of the performances of different AOPs in the phenol and 4-chlorophenol (4-CP degradation at lab and pilot scale is presented. It was found that, in the degradation of phenol, the performance of a coupled electro-oxidation/ozonation process is superior to that observed by a photo-Fenton process. Phenol removal rate was determined to be 0.83 mg L−1 min−1 for the coupled process while the removal rate for photo-Fenton process was only 0.52 mg L−1 min−1. Regarding 4-CP degradation, the complete disappearance of the molecule was achieved and the efficiency decreasing order was as follows: coupled electro-oxidation/ozonation > electro-Fenton-like process > photo-Fenton process > heterogeneous photocatalysis. Total organic carbon was completely removed by the coupled electro-oxidation/ozonation process. Also, it was found that oxalic acid is the most recalcitrant by-product and limits the mineralization degree attained by the technologies not applying ozone. In addition, an analysis on the energy consumption per removed gram of TOC was conducted and it was concluded that the less energy consumption is achieved by the coupled electro-oxidation/ozonation process.

Application of two bacterial strains for wastewater bioremediation and assessment of phenolics biodegradation.

Science.gov (United States)

Paisio, Cintia E; Quevedo, María R; Talano, Melina A; González, Paola S; Agostini, Elizabeth

2014-08-01

The use of native bacteria is a useful strategy to decontaminate industrial effluents. In this work, two bacterial strains isolated from polluted environments constitutes a promising alternative since they were able to remove several phenolic compounds not only from synthetic solutions but also from effluents derived from a chemical industry and a tannery which are complex matrices. Acinetobacter sp. RTE 1.4 showed ability to completely remove 2-methoxyphenol (1000 mg/L) while Rhodococcus sp. CS 1 not only degrade the same concentration of this compound but also removed 4- chlorophenol, 2,4-dichlorophenol and pentachlorophenol with high efficiency. Moreover, both bacteria degraded phenols naturally present or even exogenously added at high concentrations in effluents from the chemical industry and a tannery in short time (up to 5 d). In addition, a significant reduction of biological oxygen demand and chemical oxygen demand values was achieved after 7 d of treatment for both effluents using Acinetobacter sp. RTE 1.4 and Rhodococcus sp. CS1, respectively. These results showed that Acinetobacter sp. RTE1.4 and Rhodococcus sp. CS 1 might be considered as useful biotechnological tools for an efficient treatment of different effluents, since they showed wide versatility to detoxify these complex matrices, even supplemented with high phenol concentrations.

Microbial mineralization of ring-substituted anilines through an ortho-cleavage pathway.

Science.gov (United States)

Zeyer, J; Wasserfallen, A; Timmis, K N

1985-08-01

Moraxella sp. strain G is able to utilize as sole source of carbon and nitrogen aniline, 4-fluoroaniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline (PCA), and 4-bromoaniline but not 4-iodoaniline, 4-methylaniline, 4-methoxyaniline, or 3,4-dichloroaniline. The generation time on PCA was 6 h. The pathway for the degradation of PCA was investigated by analysis of catabolic intermediates and enzyme activities. Mutants of strain G were isolated to enhance the accumulation of specific pathway intermediates. PCA was converted by an aniline oxygenase to 4-chlorocatechol, which in turn was degraded via a modified ortho-cleavage pathway. Synthesis of the aniline oxygenase was inducible by various anilines. This enzyme exhibited a broad substrate specificity. Its specific activity towards substituted anilines seemed to be correlated more with the size than with the electron-withdrawing effect of the substituent and was very low towards anilines having substituents larger than iodine or a methyl group. The initial enzyme of the modified ortho-cleavage pathway, catechol 1,2-dioxygenase, had similar characteristics to those of corresponding enzymes of pathways for the degradation of chlorobenzoic acid and chlorophenol, that is, a broad substrate specificity and high activity towards chlorinated and methylated catechols.

Chloromuconolactone dehalogenase ClcF of actinobacteria.

Science.gov (United States)

Solyanikova, Inna P; Plotnikova, Elena G; Shumkova, Ekaterina S; Robota, Irina V; Prisyazhnaya, Natalya V; Golovleva, Ludmila A

2014-01-01

This work investigated the distribution of the clcF gene in actinobacteria isolated from different ecotopes. The gene encodes chloromuconolactone dehalogenase (CMLD) ClcF, the enzyme found to date in only one representative of Gram-positive bacteria, Rhodococcus opacus 1CP, adapted to 2-chlorophenol (2CP). Using primers specific to the clcF gene, from the DNA matrix of rhodococcal strains closely related to species Rhodococcus wratislaviensis (P1, P12, P13, P20, G10, KT112, KT723, BO1) we obtained PCR products whose nucleotide sequences were 100% identical to that of the clcF gene from strain R. opacus 1CP. CMLDs isolated from the biomass of strains Rhodococcus spp. G10 and P1 grown on 2CP did not differ by their subunit molecular mass deduced from the known amino acid sequence of the clcF gene from the ClcF of strain R. opacus 1CP. Matrix-assisted laser dissociation/ionization time-of-flight mass spectrometry showed the presence of a peak with m/z 11,194-11,196 Da both in whole cells and in protein solutions with a ClcF activity. Thus, we have first time shown the distribution of ClcF among actinobacteria isolated from geographically distant habitats.

Phenol remediation by peroxidase from an invasive mesquite: Turning an environmental wound into wisdom.

Science.gov (United States)

Singh, Savita; Mishra, Ruchi; Sharma, Radhey Shyam; Mishra, Vandana

2017-07-15

The present study examines mesquite (Prosopis juliflora), an invasive species, to yield peroxidase that may reduce hazards of phenolics to living organisms. As low as 0.3U of low-purity mesquite peroxidase (MPx) efficiently remove phenol and chlorophenols (90-92%) compared with Horseradish peroxidase (HRP) (40-60%). MPx shows a very high removal efficiency (40-50%) at a wide range of pH (2-9) and temperature (20-80°C), as opposed to HRP (15-20%). At a high-level of the substrate (2.4mM) and without the addition of PEG, MPx maintains a significant phenolic removal (60-≥92%) and residual activity (∼25%). It proves the superiority of MPx over HRP, which showed insignificant removal (10-12%) under similar conditions, and no residual activity even with PEG addition. The root elongation and plant growth bioassays confirm phenolic detoxification by MPx. Readily availability of mesquite across the countries and easy preparation of MPx from leaves make this tree as a sustainable source for a low-technological solution for phenol remediation. This study is the first step towards converting a biological wound of invasive species into wisdom and strength for protecting the environment from phenol pollution. Copyright © 2017 Elsevier B.V. All rights reserved.

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: Competition between C-Y (Y = halogen) and O-H bond fission

Science.gov (United States)

Sage, Alan G.; Oliver, Thomas A. A.; King, Graeme A.; Murdock, Daniel; Harvey, Jeremy N.; Ashfold, Michael N. R.

2013-04-01

The wavelength dependences of C-Y and O-H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O-H bond fission following excitation at wavelengths λ ≲ 240 nm, on repulsive ((n/π)σ*) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ˜11 000 cm-1. For Y = I and Br, this process occurs in competition with prompt C-I and C-Br bond cleavage on another (n/π)σ* PES, but no Cl/Cl* products unambiguously attributable to one photon induced C-Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C-I bond fission is observed following excitation of 4-IPhOH at all λ ≤ 330 nm; the wavelength dependent trends in I/I* product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C-I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O-H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C-Y centred (n/π)σ* potentials across the series Y = I increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to other excitation energies.

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: Competition between C–Y (Y = halogen) and O–H bond fission

International Nuclear Information System (INIS)

Sage, Alan G.; Oliver, Thomas A. A.; King, Graeme A.; Murdock, Daniel; Harvey, Jeremy N.; Ashfold, Michael N. R.

2013-01-01

The wavelength dependences of C–Y and O–H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O–H bond fission following excitation at wavelengths λ≲ 240 nm, on repulsive ((n/π)σ*) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ∼11 000 cm −1 . For Y = I and Br, this process occurs in competition with prompt C–I and C–Br bond cleavage on another (n/π)σ* PES, but no Cl/Cl* products unambiguously attributable to one photon induced C–Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C–I bond fission is observed following excitation of 4-IPhOH at all λ≤ 330 nm; the wavelength dependent trends in I/I* product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C–I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O–H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C–Y centred (n/π)σ* potentials across the series Y = I < Br < Cl and the concomitant reduction in C–Y bond strength, cf. that of the rival O–H bond, and (ii) the much increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to other excitation energies.

Enhanced fluorescence detection of dansyl derivatives of phenolic compounds using a postcolumn photochemical reactor and application to chlorophenols in river water

Energy Technology Data Exchange (ETDEWEB)

de Ruiter, C.; Bohle, J.F.; de Jong, G.J.; Brinkman, U.A.T.; Frei, R.W.

1988-04-01

Photochemical decomposition by ultraviolet (UV) irradiation of dansyl derivatives of phenolic compounds in methanol-water mixtures leads to the formation of highly fluorescent dansyl-OH and dansyl-OCH/sub 3/. With substituted phenols as model compounds, it is demonstrated that inductive effects, caused by the substituents, play a major role in the gain in fluorescence signal (up to 8000-fold) that is obtained after postcolumn UV irradiation of the dansyl derivative, compared to that of the nonirradiated derivative. The optimal irradiation time for the dansyl derivatives is about 5.5 s. All monosubstituted phenolic dansyl derivatives now have a comparable limit of detection of approximately 200 pg (S/N = 3). The calibration curve of dansylated pentachlorophenol, using the postcolumn photochemical reactor under optimal conditions, is linear over at least 3 orders of magnitude with a correlation coefficient of 0.9999 (n = 9). Application of the system to the liquid chromatographic determination of highly chlorinated phenols in river water is presented. The repeatability of the system for a river water sample, spiked with 1 ppb pentachlorophenol, is 2.4% relative standard deviation (n = 5).

UV photolysis of 4-iodo-, 4-bromo-, and 4-chlorophenol: competition between C-Y (Y = halogen) and O-H bond fission.

Science.gov (United States)

Sage, Alan G; Oliver, Thomas A A; King, Graeme A; Murdock, Daniel; Harvey, Jeremy N; Ashfold, Michael N R

2013-04-28

The wavelength dependences of C-Y and O-H bond fission following ultraviolet photoexcitation of 4-halophenols (4-YPhOH) have been investigated using a combination of velocity map imaging, H Rydberg atom photofragment translational spectroscopy, and high level spin-orbit resolved electronic structure calculations, revealing a systematic evolution in fragmentation behaviour across the series Y = I, Br, Cl (and F). All undergo O-H bond fission following excitation at wavelengths λ ≲ 240 nm, on repulsive ((n∕π)σ∗) potential energy surfaces (PESs), yielding fast H atoms with mean kinetic energies ∼11,000 cm(-1). For Y = I and Br, this process occurs in competition with prompt C-I and C-Br bond cleavage on another (n∕π)σ∗ PES, but no Cl∕Cl∗ products unambiguously attributable to one photon induced C-Cl bond fission are observed from 4-ClPhOH. Differences in fragmentation behaviour at longer excitation wavelengths are more marked. Prompt C-I bond fission is observed following excitation of 4-IPhOH at all λ ≤ 330 nm; the wavelength dependent trends in I∕I∗ product branching ratio, kinetic energy release, and recoil anisotropy suggest that (with regard to C-I bond fission) 4-IPhOH behaves like a mildly perturbed iodobenzene. Br atoms are observed when exciting 4-BrPhOH at long wavelengths also, but their velocity distributions suggest that dissociation occurs after internal conversion to the ground state. O-H bond fission, by tunnelling (as in phenol), is observed only in the cases of 4-FPhOH and, more weakly, 4-ClPhOH. These observed differences in behaviour can be understood given due recognition of (i) the differences in the vertical excitation energies of the C-Y centred (n∕π)σ∗ potentials across the series Y = I bond strength, cf. that of the rival O-H bond, and (ii) the much increased spin-orbit coupling in, particularly, 4-IPhOH. The present results provide (another) reminder of the risks inherent in extrapolating photochemical behaviour measured for one molecule at one wavelength to other (related) molecules and to other excitation energies.

Biodegradation of clofibric acid and identification of its metabolites

Energy Technology Data Exchange (ETDEWEB)

Salgado, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); ESTS-IPS, Escola Superior de Tecnologia de Setubal do Instituto Politecnico de Setubal, Rua Vale de Chaves, Campus do IPS, Estefanilha, 2910-761 Setubal (Portugal); Oehmen, A. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Carvalho, G. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnologica (IBET), Av. da Republica (EAN), 2784-505 Oeiras (Portugal); Noronha, J.P. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Reis, M.A.M., E-mail: amr@fct.unl.pt [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

2012-11-30

Graphical abstract: Metabolites produced during clofibric acid biodegradation. Highlights: Black-Right-Pointing-Pointer Clofibric acid is biodegradable. Black-Right-Pointing-Pointer Mainly heterotrophic bacteria degraded the clofibric acid. Black-Right-Pointing-Pointer Metabolites of clofibric acid biodegradation were identified. Black-Right-Pointing-Pointer The metabolic pathway of clofibric acid biodegradation is proposed. - Abstract: Clofibric acid (CLF) is the pharmaceutically active metabolite of lipid regulators clofibrate, etofibrate and etofyllinclofibrate, and it is considered both environmentally persistent and refractory. This work studied the biotransformation of CLF in aerobic sequencing batch reactors (SBRs) with mixed microbial cultures, monitoring the efficiency of biotransformation of CLF and the production of metabolites. The maximum removal achieved was 51% biodegradation (initial CLF concentration = 2 mg L{sup -1}), where adsorption and abiotic removal mechanisms were shown to be negligible, showing that CLF is indeed biodegradable. Tests showed that the observed CLF biodegradation was mainly carried out by heterotrophic bacteria. Three main metabolites were identified, including {alpha}-hydroxyisobutyric acid, lactic acid and 4-chlorophenol. The latter is known to exhibit higher toxicity than the parent compound, but it did not accumulate in the SBRs. {alpha}-Hydroxyisobutyric acid and lactic acid accumulated for a period, where nitrite accumulation may have been responsible for inhibiting their degradation. A metabolic pathway for the biodegradation of CLF is proposed in this study.

Identification of intermediates and assessment of ecotoxicity in the oxidation products generated during the ozonation of clofibric acid.

Science.gov (United States)

Rosal, Roberto; Gonzalo, María S; Boltes, Karina; Letón, Pedro; Vaquero, Juan J; García-Calvo, E

2009-12-30

The degradation of an aqueous solution of clofibric acid was investigated during catalytic and non-catalytic ozonation. The catalyst, TiO(2), enhanced the production of hydroxyl radicals from ozone and raised the fraction or clofibric acid degraded by hydroxyl radicals. The rate constant for the reaction of clofibric acid and hydroxyl radicals was not affected by the presence of the catalyst. The toxicity of the oxidation products obtained during the reaction was assessed by means of Vibrio fischeri and Daphnia magna tests in order to evaluate the potential formation of toxic by-products. The results showed that the ozonation was enhanced by the presence of TiO(2,) the clofibric acid being removed completely after 15 min at pH 5. The evolution of dissolved organic carbon, specific ultraviolet absorption at 254 nm and the concentration of carboxylic acids monitored the degradation process. The formation of 4-chlorophenol, hydroquinone, 4-chlorocatechol, 2-hydroxyisobutyric acid and three non-aromatic compounds identified as a product of the ring-opening reaction was assessed by exact mass measurements performed by liquid chromatography coupled to time-of-flight mass spectrometry (LC-TOF-MS). The bioassays showed a significant increase in toxicity during the initial stages of ozonation following a toxicity pattern closely related to the formation of ring-opening by-products.

Improvement of biodegradability of industrial wastewaters by radiation treatment

International Nuclear Information System (INIS)

Jo, H.J.; Kim, H.J.; Kim, J.G.; Jung, J.; Choi, J.S.; Park, Y.K.

2006-01-01

In order to evaluate the use of gamma-ray treatment as a pretreatment to conventional biological methods, the effects of gamma-irradiation on biodegradability (BOD 5 /COD) of textile and pulp wastewaters were investigated. For all wastewaters studied in this work, the efficiency of treatment based on TOC removal was insignificant even at an absorbed dose of 20 kGy. However, the change of biodegradability was noticeable and largely dependent on the chemical property of wastewaters and the absorbed dose of gamma-rays. For textile wastewaters, gamma-ray treatment increased the biodegradability of desizing effluent due to degradation of polymeric sizing agents such as polyvinyl alcohol. Interestingly, the weight-loss showed the highest value of 0.97 at a relatively low dose of 1 kGy. This may be caused by the degradation of less biodegradable ethylene glycol prior to terephthalic acid decomposition. For pulp wastewater, the gamma-ray treatment did not improve the biodegradability of cooking and bleaching of C/D effluents. However, the biodegradability of bleaching E1 and final effluents was abruptly increased up to 5 kGy then slowly decreased as the absorbed dose was increased. The initial increase of biodegradability may be induced by the decomposition of refractory organic compounds such as chlorophenols, which are known to be the main components of bleaching C/D and final effluents. (author)

A Novel Heterostructure of BiOI Nanosheets Anchored onto MWCNTs with Excellent Visible-Light Photocatalytic Activity

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Shijie Li

2017-01-01

Full Text Available Developing efficient visible-light-driven (VLD photocatalysts for environmental decontamination has drawn significant attention in recent years. Herein, we have reported a novel heterostructure of multiwalled carbon nanotubes (MWCNTs coated with BiOI nanosheets as an efficient VLD photocatalyst, which was prepared via a simple solvothermal method. The morphology and structure were characterized by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, UV-Vis diffuse reflectance spectroscopy (DRS, and specific surface area measurements. The results showed that BiOI nanosheets were well deposited on MWCNTs. The MWCNTs/BiOI composites exhibited remarkably enhanced photocatalytic activity for the degradation of rhodamine B (RhB, methyl orange (MO, and para-chlorophenol (4-CP under visible-light, compared with pure BiOI. When the MWCNTs content is 3 wt %, the MWCNTs/BiOI composite (3%M-Bi achieves the highest activity, which is even higher than that of a mechanical mixture (3 wt % MWCNTs + 97 wt % BiOI. The superior photocatalytic activity is predominantly due to the strong coupling interface between MWCNTs and BiOI, which significantly promotes the efficient electron-hole separation. The photo-induced holes (h+ and superoxide radicals (O2− mainly contribute to the photocatalytic degradation of RhB over 3%M-Bi. Therefore, the MWCNTs/BiOI composite is expected to be an efficient VLD photocatalyst for environmental purification.

N-TiO2/gamma-Al2O3 granules: preparation, characterization and photocatalytic activity for the degradation of 2,4-dichlorophenol.

Science.gov (United States)

Huang, Donggen; Xie, Wenfa; Tu, Zhibin; Zhang, Feng; Quan, Shuiqing; Liu, Lei

2013-01-01

Nitrogen doping TiO2 and gamma-Al2O3 composite oxide granules (N-TiO2/gamma-Al2O3) were prepared by co-precipitation/oil-drop/calcination in gaseous NH3 process using titanium sulphate and aluminum nitrate as raw materials. After calcination at 550 degrees C in NH3 atmosphere, the composite granules showed anatase TiO2 and gamma-Al2O3 phases with the granularity of 0.5-1.0 mm. The anatase crystallite size of composite granules was range from 3.5-25 nm calculated from XRD result. The UV-Vis spectra and N 1s XPS spectra indicated that N atoms were incorporated into the TiO2 crystal lattice. The product granules could be used as a photocatalyst in moving bed reactor, and was demonstrated a higher visible-light photocatalytic activity for 2,4-dichlorophenol degradation compared with commercial P25 TiO2. When the mole ratio of TiO2 to Al2O3 equal to 1.0 showed the highest catalytic activity, the degradation percentage of 2,4-chlorophenol could be up to 92.5%, under 60 W fluorescent light irradiation for 9 hours. The high visible-light photocatalytic activity might be a synergetic effect of nitrogen doping and the form of binary metal oxide of TiO2 and gamma-Al2O3.

Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Directory of Open Access Journals (Sweden)

Hayat Khan

2017-01-01

Full Text Available This study presents in detail the physicochemical, photoluminescent, and photocatalytic properties of carboxylic acid chelated nitrogen-sulphur-codoped TiO2. From the Fourier transform infrared spectroscopic study, it was revealed that the formate group formed bidentate bridging linkage while the acetate group coordinated in a bidentate chelating mode with a titanium precursor. In compliance with X-ray diffraction data, the anatase to rutile transformation temperature was extended due to carboxylic acid chelation and NS codoping. Raman analysis indicated four Raman peaks at 146, 392, 512, and 632 cm−1 for the precalcined chelated TiO2; on incorporation with NS dopants, an increase in Raman intensity for these peaks was recorded, indicating the structure stability of the anatase phase. Furthermore, X-ray photoelectron spectroscopic study revealed the presence of anionic doping of nitrogen and cationic doping of sulphur in the lattice of TiO2. When evaluating the UV-visible photodegradation rate of 4-chlorophenol, the modified TiO2 (NS0.06-TFA showed the highest photocatalytic activity. In connection with the activity tests, several scavenger agents were employed to elucidate the significance of the different reactive oxidizing species during the photocatalytic process. Moreover, the transfer pathways of photogenerated carriers and the photocatalytic reaction mechanism of modified TiO2 were also explained in detail.

Label free selective detection of estriol using graphene oxide-based fluorescence sensor

Science.gov (United States)

Kushwaha, H. S.; Sao, Reshma; Vaish, Rahul

2014-07-01

Water-soluble and fluorescent Graphene oxide (GO) is biocompatible, easy, and economical to synthesize. Interestingly, GO is also capable of quenching fluorescence. On the basis of its fluorescence and quenching abilities, GO has been reported to serve as an energy acceptor in a fluorescence resonance energy transfer (FRET) sensor. GO-based FRET biosensors have been widely reported for sensing of proteins, nucleic acid, ATP (Adenosine triphosphate), etc. GO complexes with fluorescent dyes and enzymes have been used to sense metal ions. Graphene derivatives have been used for sensing endocrine-disrupting chemicals like bisphenols and chlorophenols with high sensitivity and good reproducibility. On this basis, a novel GO based fluorescent sensor has been successfully designed to detect estriol with remarkable selectivity and sensitivity. Estriol is one of the three estrogens in women and is considered to be medically important. Estriol content of maternal urine or plasma acts as an important screening marker for estimating foetal growth and development. In addition, estriol is also used as diagnostic marker for diseases like breast cancer, osteoporosis, neurodegenerative and cardiovascular diseases, insulin resistance, lupus erythematosus, endometriosis, etc. In this present study, we report for the first time a rapid, sensitive with detection limit of 1.3 nM, selective and highly biocompatible method for label free detection of estriol under physiological conditions using fluorescence assay.

Removal of absorbable organic halides (aox) from recycled paper mill effluent using granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR)

International Nuclear Information System (INIS)

Mohamad, A.B.; Rahman, R.A.; Kadhum, A.A.H.; Abdullah, S.R.S.; Shaari, S.

2006-01-01

Paper mills generate varieties of pollutants depending upon the type of the pulping process. Paper mill wastewaters have high chemical oxygen demand (COD) and colour, indicating high concentrations of recalcitrant organics. The study was conducted employing a Granular Activated Carbon - Sequencing Batch Biofilm Reactor (GAC-SBBR), containing 3.0 L working volume, operated in aerobic condition and packed with 200 g/L of 2-3 mm granular activated carbon (coconut shells) as a medium for biofilm growth. For the first couple of month, the HRT was 36 hours and the HRT of this reactor was adjusted to 24 hours in order to evaluate the performance of the system. The treated wastewater sample for these studies came from a recycle paper factory from MNI Sdn Bhd with 4 different samples characteristics. The adsorbable organic halides (AOX) to be determined and treated were Pentachlorophenol (PCP), 2,3,4,5-Tetrachlorophenol (2,3,4,5-TeCP), 2,4,6-Trichlorophenol (2,4,6-TCP), 2,4-Dichlorophenol ( 2,4-DCP), 2-Chlorophenol (CP) and phenol. Results showed that, the biofilm attached onto granular activated carbon (GAC) could substantially remove these recalcitrant in the wastewater. More over, results from the studies showed that high removal was achieved by the biofilm SBR with 10-100% removal of AOX and depending on HRT. (Author)

Structural, absorption, and molecular properties of o,o'-dihydroxyazo resorcinol dyes bearing an acryloyloxy group

Science.gov (United States)

Özkınalı, Sevil; Çavuş, M. Serdar; Ceylan, Abdullah; Gür, Mahmut

2017-12-01

To the best of our knowledge, this is the first study reporting the synthesis and characterization of o,o‧-dihydroxyazo dyes bearing an acryloyl group. The o,o‧-dihydroxyazo dyes were synthesized through coupling of resorcinol with the diazonium salts of 2-amino-4-methylphenol, 2-aminophenol, 2-amino-4-chlorophenol, and 2-amino-4-nitrophenol. Their acryloyl derivatives were synthesized using metallic sodium and acryloyl chloride under an inert atmosphere. Characterization of the compounds was conducted using infrared (IR), ultraviolet-visible (UV-vis), proton nuclear magnetic resonance (1H NMR), and carbon nuclear magnetic resonance (13C NMR) spectroscopic methods. The tautomerism of the synthesized compounds' was also evaluated. The results were compared with theoretical results obtained by density functional theory (DFT). The DFT calculations were performed to obtain ground-state optimized geometries and calculate the relevant electronic and chemical reactivity parameters. Furthermore, possible tautomers deduced from the UV-vis spectra were investigated using theoretical calculations. Both the IR and NMR spectral data showed that azo tautomers predominate in the solid state and DMSO solvent. The effects of pH, solvent, and substituent on the predominant tautomers were further investigated through UV-vis spectroscopy. The results indicate that hydrazone tautomers were dominant at pH 12 in dimethylformamide (DMF), whereas azo tautomers were dominant at pH 2 in EtOH or CHCl3.

Liquid phase deposition of WO3/TiO2 heterojunction films with high photoelectrocatalytic activity under visible light irradiation

International Nuclear Information System (INIS)

Zhang, Man; Yang, Changzhu; Pu, Wenhong; Tan, Yuanbin; Yang, Kun; Zhang, Jingdong

2014-01-01

Highlights: • Liquid phase deposition is developed for preparing WO 3 /TiO 2 heterojunction films. • TiO 2 film provides an excellent platform for WO 3 deposition. • WO 3 expands the absorption band edge of TiO 2 film to visible light region. • WO 3 /TiO 2 heterojunction film shows high photoelectrocatalytic activity. - ABSTRACT: The heterojunction films of WO 3 /TiO 2 were prepared by liquid phase deposition (LPD) method via two-step processes. The scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopic analysis indicated that flower-like WO 3 film was successfully deposited on TiO 2 film with the LPD processes. The TiO 2 film provided an excellent platform for WO 3 deposition while WO 3 obviously expanded the absorption of TiO 2 film to visible light. As the result, the heterojunction film of WO 3 /TiO 2 exhibited higher photocurrent response to visible light illumination than pure TiO 2 or WO 3 film. The photoelectrocatalytic (PEC) activity of WO 3 /TiO 2 film was evaluated by degrading Rhodamin B (RhB) and 4-chlorophenol (4-CP) under visible light irradiation. The results showed that the LPD WO 3 /TiO 2 film possessed high PEC activity for efficient removal of various refractory organic pollutants

Assessment of PCDD/Fs levels in soil at a contaminated sawmill site in Sweden – A GIS and PCA approach to interpret the contamination pattern and distribution

International Nuclear Information System (INIS)

Henriksson, S.; Hagberg, J.; Bäckström, M.; Persson, I.; Lindström, G.

2013-01-01

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) were analysed in soil from a Swedish sawmill site where chlorophenols (CPs) had been used more than 40 years ago. The most contaminated area at the site was the preservation subarea where the PCDD/F WHO 2005 -TEQ level was 3450 times higher than the current Swedish guideline value of 200 ng TEQ/kg soil for land for industrial use. It was also shown that a fire which destroyed the sawmill might have affected the congener distribution at the concerned areas. To get a broader picture of the contamination both GIS (spatial interpolation analysis) and multivariate data analysis (PCA) were applied to visualize and compare PCDD/F levels as well as congener distributions at different areas at the site. It is shown that GIS and PCA are powerful tools in decisions on future investigations, risk assessments and remediation of contaminated sites. -- Highlights: •GIS and PCA visualize and compare site levels and congener patterns of dioxins. •Subareas were separated by differences in contamination levels and congener patterns. •Fire had a significant effect on the congener distribution at the site. -- The use of geostatistical and multivariate statistical methods are powerful tools to visualize the contamination pattern and distribution at a highly PCDD/Fs-contaminated site

Absorption, distribution, metabolism and excretion of 14C-chlorphenesin carbamate in rats

International Nuclear Information System (INIS)

Nozu, Takashi; Aoyagi, Tadao; Setoyama, Kageyoshi; Suwa, Toshio; Tanaka, Ichiro

1977-01-01

Absorption, distribution, metabolism and excretion of chlorphenesin carbamate (CPC), a central acting muscle relaxant, were investigated in rats by use of 14 C-labeled CPC. After oral administration, 14 C-CPC was well absorbed from gastrointestinal tract and about 90% of the given radioactivity was excreted in urine and 5% in feces during 5 days. Approximately 36% was recovered in bile during 8 hr after oral administration. The highest blood level of 14 C was observed at 3-8 hr after oral administration and decreased slowly. The radioactivity was distributed widely in almost all tissues. The highest concentration of 14 C was observed in the liver and the higher was detected in the brain and spinal cord, suggesting a pharmacological effect of CPC. In pregnant rats given 14 C-CPC orally, the radioactivity in the fetuses was below 0.8% of the dose at 1-24 hr. The major metabolites in 48 hr urine was identified as CPC-glucuronide and the acidic metabolites, p-chlorophenoxylactic acid, p-chlorophenoxyacetic acid and p-chlorophenol, were also detected. After intravenous injection of the 14 C-labeled acidic metabolites, the radioactivity was not detected in the central nervous system and excreted rapidly. In the case of repeated administration of CPC and 14 C-CPC for 21 days, the radioactivity did not accumulated in any tissue of rats. (auth.)

Structural basis for the substrate specificity and the absence of dehalogenation activity in 2-chloromuconate cycloisomerase from Rhodococcus opacus 1CP.

Science.gov (United States)

Kolomytseva, Marina; Ferraroni, Marta; Chernykh, Alexey; Golovleva, Ludmila; Scozzafava, Andrea

2014-09-01

2-Chloromuconate cycloisomerase from the Gram-positive bacterium Rhodococcus opacus 1CP (Rho-2-CMCI) is an enzyme of a modified ortho-pathway, in which 2-chlorophenol is degraded using 3-chlorocatechol as the central intermediate. In general, the chloromuconate cycloisomerases catalyze not only the cycloisomerization, but also the process of dehalogenation of the chloromuconate to dienelactone. However Rho-2-CMCI, unlike the homologous enzymes from the Gram-negative bacteria, is very specific for only one position of the chloride on the substrate chloromuconate. Furthermore, Rho-2-CMCI is not able to dehalogenate the 5-chloromuconolactone and therefore it cannot generate the dienelactone. The crystallographic structure of the homooctameric Rho-2-CMCI was solved by molecular replacement using the coordinates of the structure of chloromuconate cycloisomerase from Pseudomonas putida PRS2000. The structure was analyzed and compared to the other already known structures of (chloro)muconate cycloisomerases. In addition to this, molecular docking calculations were carried out, which allowed us to determine the residues responsible for the high substrate specificity and the lack of dehalogenation activity of Rho-2-CMCI. Our studies highlight that a histidine, located in a loop that closes the active site cavity upon the binding of the substrate, could be related to the dehalogenation inability of Rho-2-CMCI and in general of the muconate cycloisomerases. Copyright © 2014 Elsevier B.V. All rights reserved.

[Chlorine speciation and concentration in cultivated soil in the northeastern China studied by X-ray absorption near edge structure].

Science.gov (United States)

Li, Jing; Lang, Chun-Yan; Ma, Ling-Ling; Xu, Dian-Dou; Zheng, Lei; Lu, Yu-Nanz; Cui Li-Rui; Zhang, Xiao-Meng

2014-10-01

A procedure has been proposed to determine chlorine speciation and concentration in soil with X-ray absorption near edge structure (XANES), and this method was applied to study the cultivated soil (bog, dark brown and black cultivated soil) in the Northeastern China. Qualitative analysis was carried out by least-squares fitting of sample spectra with standard spectra of three model compounds (NaCl, 3-chloropropionic acid, chlorophenol red). Linear correlation between the absolute fluorescence intensity of a series of NaCl standards and the Cl concentration was used as quantification standard for measuring the total Cl concentration in samples. The detection limits,relative standard deviation (RSD), recoveries were 2 mg · kg(-1), 0%-5% and 77%-133%, respectively. The average concentration of total Cl was 19 mg · kg(-1). The average relative content was as high as 61% of organochlorine with the concentration of 1-2 times as high as the concentration of inorganic chloride. The distribution trend of the total Cl, inorganic chloride and organic chlorine in different types of soil was: bog arable soil > dark brown soil > black soil. In conclusion, XANES is a reliable method to nondestructively characterize the speciation and concentration of chlorine in soil, which would provide some basic data for the future study of the chlorine's biogeochemical transformations.

P(o-chlorophenol–co-o-hydroxyphenol: kinetic formation studies and pH-sensor application

Directory of Open Access Journals (Sweden)

Said M. Sayyah

2017-03-01

Full Text Available Electrochemical copolymerization of o-chlorophenol (o-ClPh with o-hydroxyphenol (o-HOPh was conducted in aqueous H2SO4 using cyclic voltammetry technique at the Pt electrode. The reaction rate was found to be of the second order in the monomer concentration and first order in the acid concentration. The activation energy, enthalpy, and entropy for the copolymerization were found to be 20.20 kJ mol-1, 19.24 kJ mol-1 and -281.47 J K-1 mol-1, respectively. The obtained copolymer films show smooth feature with amorphous nature. Copolymer films adhere Pt electrode very well and show less reactivity in the H2SO4 medium. The pH sensitivity of the poly(oClPh-co-HOPh-modified electrode has been investigated potentiometrically using different polymer thicknesses. The potentiometric responses to pH change of the poly(oClPh-co-HOPh-modified electrode appeared reversible and linear in the range from pH 2-11 with a maximum sub-Nernstian potentiometric response slope of 40.7 mV/pH (30 °C. The slope became close to 56.2 mV/pH in the range from pH 4 to 9 at (30 °C. The poly(oClPh-co-HOPh-modified electrode readily responded to pH change but was not stable with time.

Reaction kinetic model of the surface-mediated formation of PCDD/F from pyrolysis of 2-chlorophenol on a CuP/Silica suface

Energy Technology Data Exchange (ETDEWEB)

Lomnicki, S.; Khachatryan, L.; Dellinger, B. [Louisiana State Univ., Baton Rouge (United States). Dept. of Chemistry

2004-09-15

One of the major challenges in developing predictive models of the surface mediated pollutant formation and fuel combustion is the construction of reliable reaction kinetic mechanisms and models. While the homogeneous, gas-phase chemistry of various light fuels such as hydrogen and methane is relatively well-known large uncertainties exist in the reaction paths of surface mediated reaction mechanisms for even these very simple species. To date, no detailed kinetic consideration of the surface mechanisms of formation of complex organics such as PCDD/F have been developed. In addition to the complexity of the mechanism, a major difficulty is the lack of reaction kinetic parameters (pre-exponential factor and activation energy) of surface reactions, Consequently, numerical studies of the surface-mediated formation of PCDD/F have often been incorporated only a few reactions. We report the development of a numerical multiple-step surface model based on experimental data of surface mediated (5% CuO/SiO2) conversion of 2-monochlorphenol (2-MCP) to PCDD/F under pyrolytic or oxidative conditions. A reaction kinetic model of the catalytic conversion of 2-MCP on the copper oxide catalyst under pyrolytic conditions was developed based on a detailed multistep surface reaction mechanism developed in our laboratory. The performance of the chemical model is assessed by comparing the numerical predictions with experimental measurements. SURFACE CHEMKIN (version 3.7.1) software was used for modeling. Our results confirm the validity of previously published mechanism of the reaction and provides new insight concerning the formation of PCDD/F formation in combustion processes. This model successfully explains the high yields of PCDD/F at low temperatures that cannot be explained using a purely gas-phase mode.

Organic compounds in concrete from demolition works.

Science.gov (United States)

Van Praagh, M; Modin, H; Trygg, J

2015-11-01

This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work. Copyright © 2015. Published by Elsevier Ltd.

Synthesis and characterization of Ag₃PO₄ immobilized with graphene oxide (GO) for enhanced photocatalytic activity and stability over 2,4-dichlorophenol under visible light irradiation.

Science.gov (United States)

Chen, Xiao-juan; Dai, You-zhi; Wang, Xing-yan; Guo, Jing; Liu, Tan-hua; Li, Fen-fang

2015-07-15

A series of visible-light responsive photocatalysts prepared using Ag3PO4 immobilized with graphene oxide (GO) with varying GO content were obtained by an electrostatically driven method, and 2,4-dichlorophenol (2,4-DCP) was used to evaluate the performance of the photocatalysts. The composites exhibited superior photocatalytic activity and stability compared with pure Ag3PO4. When the content of GO was 5%, the degradation efficiency of 2,4-DCP could reach 98.95%, and 55.91% of the total organic (TOC) content was removed within 60 min irradiation. Meanwhile, the efficiency of 91.77% was achieved for 2,4-DCP degradation even after four times of recycling in the photocatalysis/Ag3PO4-GO (5%) system. Reactive species of O2(˙-), OH˙ and h(+) were considered as the main participants for oxidizing 2,4-DCP, as confirmed by the free radical capture experiments. And some organic intermediates including 4-chlorophenol (4-CP), hydroquinone (HQ), benzoquinone (BZQ), 2-chlorohydroquinone and hydroxyhydroquinone (HHQ) were detected by comparison with the standard retention times from the high performance liquid chromatography (HPLC). In short, the enhanced photocatalytic property of Ag3PO4-GO was closely related to the strong absorption ability of GO relative to 2,4-DCP, the effective separation of photogenerated electron-hole pairs, and the excellent electron capture capability of GO. Copyright © 2015. Published by Elsevier B.V.

Direct in situ activation of Ag0 nanoparticles in synthesis of Ag/TiO2 and its photoactivity

International Nuclear Information System (INIS)

Jaafar, N.F.; Jalil, A.A.; Triwahyono, S.; Efendi, J.; Mukti, R.R.; Jusoh, R.; Jusoh, N.W.C.; Karim, A.H.; Salleh, N.F.M.; Suendo, V.

2015-01-01

Graphical abstract: - Highlights: • Ag 0 loaded on TiO 2 was prepared by a direct in situ electrochemical method. • 5 wt% Ag–TiO 2 demonstrated the best photocatalytic degradation of 2-CP. • Isomorphous substitution of Ag with Ti occurred to form Ti−O−Ag bonds. • Ag 0 and oxygen vacancies trapped electrons to enhance e–H + separation. • Substitution of Ag in the TiO 2 structure decreased the number of oxygen vacancies. - Abstract: Metallic Ag nanoparticles (Ag 0 ) were successfully activated using a direct in situ electrochemical method before being supported on TiO 2 . Catalytic testing showed that 5 wt% Ag–TiO 2 gave the highest photodegradation (94%) of 50 mg L −1 2-chlorophenol (2-CP) at pH 5 using 0.375 g L −1 catalyst within 6 h, while under similar conditions, 1 wt% and 10 wt% Ag–TiO 2 only gave 75% and 78% degradation, respectively. Characterization results illustrated that the photoactivity was affected by the amount of Ag 0 and oxygen vacancies which act as an electrons trap to enhance the electron–hole separation. While, the Ag−O−Ti bonds formation reduced the photoactivity. The degradation followed a pseudo-first order Langmuir–Hinshelwood model where adsorption was the controlling step. Study on the effect of scavengers showed that the hole (H + ) and hydroxyl radical (OH·) play important roles in the photodegradation. The regenerated photocatalyst was still stable after five cycling runs

A review of dioxin-related substances during municipal solid waste incineration.

Science.gov (United States)

Zhou, Hui; Meng, Aihong; Long, Yanqiu; Li, Qinghai; Zhang, Yanguo

2015-02-01

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are among the most toxic chemicals and the main restriction on municipal solid waste incineration. To exert more effective control over the formation of dioxin homologues during municipal solid waste incineration, it is significant to investigate dioxin-related compounds. Despite the numerous studies about PCDD/Fs, a unified understanding regarding many problems has yet to be reached because the homologues of PCDD/Fs are excessive, the measurement of PCDD/Fs is difficult, and the formation mechanisms of PCDD/Fs are complicated. Firstly, this paper briefly introduces the different formation mechanisms of PCDD/Fs, including high temperature homogeneous reaction PCDD/Fs formation and low temperature heterogeneous reaction PCDD/Fs formation. Then the sources of PCDD/Fs including precursors (chlorophenols and polycyclic aromatic hydrocarbons) and residual carbon are summarized. In particular, this paper analyzes the substances that influence PCDD/Fs formation and their impact mechanisms, including different categories of chlorine (Cl2, HCl and chloride in fly ash), O2, copper, sulfur, water, and nitrogen compounds (ammonia and urea). Due to the high cost and complexity of PCDD/Fs measurement, PCDD/Fs indicators, especially chlorobenzenes and polycyclic aromatic hydrocarbons, are summarized, to find an effective surrogate for quick, convenient and real-time monitoring of PCDD/Fs. Finally, according to the results of the current study, recommendations for further research and industrial applications prospects are proposed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Metabolism studies of diclofenac and clofibric acid in activated sludge bioreactors using liquid chromatography with quadrupole - time-of-flight mass spectrometry

Science.gov (United States)

Kosjek, Tina; Heath, Ester; Pérez, Sandra; Petrović, Mira; Barceló, Damia

2009-06-01

SummaryTwo environmentally relevant pharmaceuticals, the non-steroidal antiinflammatory drug, diclofenac and the pharmacologically active metabolite of several serum triglyceride-lowering pharmaceuticals, clofibric acid, were subjected to microbiological transformation in activated sludge bioreactors, and the production of breakdown products was studied. For separation, detection and identification of diclofenac's metabolites a UPLC-(+)ESI-QqToF-MS was employed, which enabled the detection of seven transformation products of diclofenac, all including the diagnostic fragment ion at m/z 214. The chemical structure of one metabolite was proposed, which was produced by dehydratation and lactame formation. Further investigations revealed additional two metabolites, which were isomeric structures with an elemental composition C 13H 10NCl 2; however, their chemical structures were not completely resolved. In addition, another biodegradation product showed an abundant fragment ion at m/z 295, the elemental composition of which was confirmed with a high degree of certainty as C 14H 11NO 2Cl 2. The biodegradation of clofibric acid revealed one metabolite in the (-)ESI-QqToF chromatogram, 4-chlorophenol, which is known to exhibit a higher toxicity than the parent compound. This study confirms that further research is needed on the formation of stable metabolites both during wastewater treatment and in the environment. It also highlights the need for parallel toxicity testing. In addition, this study suggests that more needs to be known about the environmental fate of pharmaceuticals so that we are able to provide a comprehensive risk assessment.

Use of olive oil for soil extraction and ultraviolet degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans.

Science.gov (United States)

Isosaari, P; Tuhkanen, T; Vartiainen, T

2001-03-15

This paper represents a successful laboratory-scale photolysis of soil-bound tetra- to octachlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in olive oil. The irradiation source consisted of two blacklight lamps emitting light at a near-ultraviolet range. Samples used in the experiments included pure 1,2,3,4,6,7,8-heptachlorodibenzofuran, PCDD/F extract made of a wood preservative (chlorophenol product Ky 5), and soil that was highly contaminated with PCDD/Fs. Degradation of 1,2,3,4,6,7,8-heptachlorodibenzofuran dissolved in olive oil proceeded rapidlywith a first-order reaction half-life of 13 min. Irradiation of a soil sample resulted in an 84% reduction in PCDD/F toxicity equivalent (I-TEQ) in 17.5 h. A more complete degradation of soil-bound PCDD/Fs was achieved after extraction of the soil with olive oil. The oil was effective in solubilizing PCDD/Fs. After one extraction at room temperature, only 9% of I-TEQ remained in soil. Irradiation of the resulting extract reduced toxicity of the extract by 99%, and even the highly chlorinated congeners octachlorodibenzo-p-dioxin and octachlorodibenzofuran degraded easily (97 and 99% degradation, respectively). Photodegradation byproducts found included diphenyl ether and small amounts of dechlorination products, which were mainly nontoxic PCDD/Fs. Degradation was probably mediated by light absorption of unsaturated fatty acids and phenolic compounds in olive oil, leading to sensitized photolysis of PCDD/Fs.

Investigations to identify organic pollutions in sewer slime. Final report; Untersuchungen zur Identifizierung organischer Schadstoffe in Sielhaeuten. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Antusch, E.; Sauer, J.; Ripp, C.; Hahn, H.H.

1997-07-31

An analytical method to measure organic compounds in sewer slime and sewage sludge has been developed. The method needs no halogenated solvents. Furthermore, the sorption behavior of sewer slime has been investigated. Chlorophenols, as an example of more polar organic compounds, show a more stronger and faster desorption from sewer slime than for example PAH. pH-value and fat-content (resp. content of organic carbon) are the most important parameters affecting the sorption kinetic and sorption capacity of sewer slime. To get comparable results, all datas should be refered to the content of organic carbon of the sewer slime. By constructing pollutions-profiles of parameters like AOX, PCB, Flame Protection Agencies and PAH in the sewers of an industrial area, emissions could be localized. (orig.) [Deutsch] Es wurde eine analytische Methode entwickelt, die es erlaubt, ein breites Spektrum lipophiler organischer Schadstoffe in Sielhaut und Klaerschlamm zu identifizieren, als quantitativ zu bestimmen. Die Methode kommt ohne halogenierte Loesungsmittel aus. Verbindungen, die aufgrund ihrer Wasserunloeslichkeit nicht im Abwasser nachgewiesen werden konnten, koennen durch Sielhautanalyse verfolgt werden. Anhand von Schadstoffprofilen in Nebensammlern eines Industriegebietes konnte beispielhaft die Lokalisierung von punktfoermigen Schadstoffeinleitungen demonstriert werden. Erfolgreich verlief auch die Identifizierung eines AOX-Emittenten. Ebenso sind die Eintragspfade von Stoffen, die im Verdacht stehen, endokrine Wirkungen zu haben mit Sielhautanalyse aufklaerbar. Das Sorptionsverhalten der Sielhaut wird durch Faktoren, wie pH und Fettgehalt gepraegt. Bei der Auswertung der Proben muessen die Werte auf den organischen Kohlenstoffgehalt bezogen werden. (orig.)

[Formation mechanism and chemical safety of nonintentional chemical substances present in chlorinated drinking water and wastewater].

Science.gov (United States)

Onodera, Sukeo

2010-09-01

This paper reviews the formation mechanism and chemical safety of nonintentional chemical substances (NICS) present in chlorine-treated water containing organic contaminants. Undesirable compounds, i.e., NICS, may be formed under certain conditions when chlorine reacts with organic matter. The rate and extent of chlorine consumption with organics are strongly dependent on their chemical structures, particularly whether double bonds or sulfur and nitrogen atoms occur in the molecules. Organothiophosphorus pesticides (P=S type) are easily oxidized to their phosphorus compounds (P=O type) in chlorinated water containing HOCl as little as 0.5 mg/l, resulting in an increase in cholinesterase-inhibitory activity. Chlorination of phenols in water also produces a series of highly chlorinated compounds, including chlorophenols, chloroquinones, chlorinated carboxylic acids, and polychlorinated phenoxyphenols (PCPPs). In some of these chloroquinones, 2,6-dichloroalkylsemiquinones exhibit a strong mutagenic response as do positive controls used in the Ames test. 2-phenoxyphenols in these PCPPs are particularly interesting, as they are present in the chlorine-treated phenol solution and they are also precursors (predioxins) of the highly toxic chlorinated dioxins. Polynuclear aromatic hydrocarbons (PAHs) were found to undergo chemical changes due to hypochlorite reactions to give chloro-substituted PAHs, oxygenated (quinones) and hydroxylated (phenols) compounds, but they exhibit a lower mutagenic response. In addition, field work was performed in river water and drinking water to obtain information on chemical distribution and their safety, and the results are compared with those obtained in the model chlorination experiments.

Facile preparation of multifunctional carbon nanotube/magnetite/polyaniline nanocomposite offering a strong option for efficient solid-phase microextraction coupled with GC-MS for the analysis of phenolic compounds.

Science.gov (United States)

Tafazoli, Zahra; Azar, Parviz Aberoomand; Tehrani, Mohammad Saber; Husain, Syed Waqif

2018-04-20

The aim of this study the synthesis of a highly efficient organic-inorganic nanocomposite. In this research, the carbon nanotube/magnetite/polyaniline nanocomposite was successfully prepared through a facile route. Monodisperse magnetite nanospheres were prepared through the coprecipitation route, and polyaniline nanolayer as a modified shell with a high surface area was synthesized by an in situ growth route and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The prepared nanocomposite was immobilized on a stainless-steel wire for the fabrication of the solid-phase microextraction fiber. The combination of headspace solid-phase microextraction using carbon nanotube/magnetite/polyaniline nanocomposite fiber with gas chromatography and mass spectrometry can achieve a low limit of detection and can be applied to determine phenolic compounds in water samples. The effects of the extraction and desorption parameters including extraction temperature and time, ionic strength, stirring rate, pH, and desorption temperature and time have been studied. Under the optimum conditions, the dynamic linear range was 0.01-500 ng mL -1 and the limits of detection of phenol, 4-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol were the lowest (0.008 ng mL -1 ) for three times. The coefficient of determination of all calibration curves was more than 0.990. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Reductive destruction and decontamination of aqueous solutions of chlorinated antimicrobial agent using bimetallic systems

Energy Technology Data Exchange (ETDEWEB)

Ghauch, Antoine, E-mail: antoine.ghauch@aub.edu.lb [American University of Beirut, Faculty of Arts and Sciences, Department of Chemistry, P.O. Box 11-0236 Riad El Solh, 1107-2020 Beirut (Lebanon); Tuqan, Almuthanna [American University of Beirut, Faculty of Arts and Sciences, Department of Chemistry, P.O. Box 11-0236 Riad El Solh, 1107-2020 Beirut (Lebanon)

2009-05-30

Palladium, ruthenium and silver were investigated as catalysts for the dechlorination of dichlorophen (DCP, 2,2'-methylenebis(4-chlorophenol)), an antimicrobial and anthelmintic agent largely used as algicide, fungicide and bactericide. Experiments were undertaken under oxic and anoxic conditions for experimental durations up to 180 min (3 h). The anoxic conditions were achieved by purging the solutions with nitrogen gas. Reactions were performed in a 12 {+-} 0.5 mg L{sup -1} DCP solution (V = 20 mL) using 0.8 g of Fe{sup 0} (40 g L{sup -1}). Along with micrometric Fe{sup 0}, five Fe{sup 0}-plated systems were investigated: Pd (1%), Ru (0.01%), Ru (0.1%), Ru (1%) and Ag (1%). Metal plating was controlled by atomic absorption spectroscopy. DCP degradation was monitored using: (i) two HPLC devices, (ii) ion chromatography, (iii) UV and fluorescence spectrophotometry. Results indicated: (i) total dechlorination with Fe/Pd, (ii) partial dechlorination (40%) with Fe/Ru, and no reaction with Fe/Ag. DCP is vanished completely after 90 min of contact with Fe/Pd following a first order kinetic. The observed degradation rate k{sub obs} was about (3.98 {+-} 0.10) x 10{sup -2} min{sup -1}, the calculated half-life t{sub 1/2} about 17.4 {+-} 0.9 min and a t{sub 50} about 10.1 {+-} 0.5 min. A DCP degradation pathway map was also proposed.

Competitive binding of polyethyleneimine-coated gold nanoparticles to enzymes and bacteria: a key mechanism for low-level colorimetric detection of gram-positive and gram-negative bacteria

International Nuclear Information System (INIS)

Thiramanas, Raweewan; Laocharoensuk, Rawiwan

2016-01-01

The article describes a simple and rapid method for colorimetric detection of bacteria. It is based on competitive binding of positively charged polyethyleneimine-coated gold nanoparticles (PEI-AuNPs) to negatively charged enzymes and bacteria. The PEI-AuNPs are electrostatically attracted by both the bacterial surface and the enzyme β-galactosidase (β-Gal). Binding to the latter results in the inhibition of enzyme activity. However, in the presence of a large number of bacteria, the PEI-AuNPs preferentially bind to bacteria. Hence, the enzyme will not be inhibited and its activity can be colorimetrically determined via hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside (CPRG). The detection limit of this assay is as low as 10 cfu·mL −1 , and the linear range extends from 10 6 to 10 8 cfu·mL −1 . The assay is applicable to both Gram-negative (such as enterotoxigenic Escherichia coli; ETEC) and Gram-positive (Staphylococcus aureus; S. aureus) bacteria. Results are obtained within 10 min using an optical reader, and within 2–3 h by bare-eye detection. The method was applied to the identification of ETEC contamination at a level of 10 cfu·mL −1 in spiked drinking water. Given its low detection limit and rapidity (sample preconcentration is not required), this method holds great promise for on-site detection of total bacterial contamination. (author)

Influences of chlorine content on emission of HCl and organic compounds in waste incineration using fluidized beds.

Science.gov (United States)

Wey, M Y; Liu, K Y; Yu, W J; Lin, C L; Chang, F Y

2008-01-01

HCl and some organic compounds are the precursors of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in municipal solid waste incinerators. In this work, a lab-scale fluidized bed incinerator is adopted to study the relationship between the organic and the inorganic chlorine contents of artificial wastes and the emissions of HCl and organic compounds. The lower threshold limit (LTL) of chlorine content below which HCl and organic compounds are not generated is studied. Experimental results showed that organic chlorides had a greater potential to release chlorine than inorganic chlorides. The generation of organic pollutants fell, but the emissions of HCl increased with the temperature. The concentrations of chlorophenols (CPs)/chlorobenzenes (CBs) increased with chlorine contents. No LTL existed for HCl regardless of whether CaO was added. The LTL for CPs was between 0.1 and 0.3wt% of inorganic chloride, but there was none for organic sources. For CBs, the LTL was between 0.5 and 1.0wt% for inorganics at 700 and 800 degrees C, but 0.1-0.3 wt% at 700 degrees C and 0.3-0.5 wt% at 800 degrees C for organics. The production of PAHs and benzene, toluene, ethylbenzene and xylene (BTEX) was related to the surplus hydrogen ions that were not reacted with the chlorine. Adding CaO inhibited the production of HCl, CBs and CPs, but did not seriously affect PAHs and BTEX.

Analysis of organic micropollutants in drinking water using SPME and GC-MS

International Nuclear Information System (INIS)

Guidotti, M.; Ravaioli, G.

1999-01-01

In this work the purpose was to develop accurate and reproducible methods for the qualitative and quantitative analysis of pesticides/herbicides, phthalates, chlorinated solvents, trihalomethanes, polycyclic aromatic hydrocarbons (PAHs) and chlorophenols in drinking waters, using solid-phase micro extraction and GC-MS techniques. The SPME developed by J. Pawliszyn and co-workers, consists of an fused silica fibre, coated with an appropriate absorbent phase, hosted inside the needle of a holder that looks like a GC-syringe; the needle pierces the septum of a sealed vial and the fibre is lowered, by depressing the plunger of the holder, into the liquid (or in the headspace, if that is the case) that contains the analytes of interest. After a set period of time, necessary to reach the partitioning equilibrium, the fibre is retracted inside the needle, the needle is inserted into the GC injector port and the fibre pushed in the heated injector. Here the compounds of interest (that have adsorbed onto the fibre) are thermally desorbed and analysed by GC-MS. After three minutes the fibre is extracted and is ready for a new analysis. The SPME technique has already found many applications in food and environmental analysis. Many of the analytes investigated in this research are listed Italian legislation as possible pollutants of drinking waters and their presence and concentrations require monitoring. The list of compounds included in this work is reported in Table 1

Influence of the iron source on the solar photo-Fenton degradation of different classes of organic compounds

Energy Technology Data Exchange (ETDEWEB)

Nogueira, R.F.P.; Silva, M.R.A.; Trovo, A.G. [UNESP, Sao Paulo State University, Institute of Chemistry of Araraquara, P.O. Box 355, 14800-970, Araraquara, SP (Brazil)

2005-10-01

In this work the influence of two different iron sources, Fe(NO{sub 3}){sub 3} and complexed ferrioxalate (FeOx), on the degradation efficiency of 4-chlorophenol (4CP), malachite green, formaldehyde, dichloroacetic acid (DCA) and the commercial products of the herbicides diuron and tebuthiuron was studied. The oxidation of 4CP, DCA, diuron and tebuthiuron shows a strong dependence on the iron source. While the 4CP degradation is favored by the use of Fe(NO{sub 3}){sub 3}, the degradation of DCA and the herbicides diuron and tebuthiuron is most efficient when ferrioxalate is used. On the other hand, the degradation of malachite green and formaldehyde is not very influenced by the iron source showing only a slight improvement when ferrioxalate is used. In the case of formaldehyde, DCA, diuron and tebuthiuron, despite of the additional carbon introduced by the use of ferrioxalate, higher mineralization percentages were observed, confirming the beneficial effect of ferrioxalate on the degradation of these compounds. The degradation of tebuthiuron was studied in detail using a shallow pond type solar flow reactor of 4.5L capacity and 4.5cm solution depth. Solar irradiation of tebuthiuron at a flow rate of 9Lh{sup -1}, in the presence of 10.0mmolL{sup -1} H{sub 2}O{sub 2} and 1.0mmolL{sup -1} ferrioxalate resulted in complete conversion of this herbicide and 70% total organic carbon removal. (author)

The analysis of aqueous mixtures using liquid chromatography-electrospray mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Johnson, Steven [Iowa State Univ., Ames, IA (United States)

1999-02-12

The focus of this dissertation is the use of chromatographic methods coupled with electrospray mass spectrometry (ES-MS) for the determination of both organic and inorganic compounds in aqueous solutions. The combination of liquid chromatography (LC) methods and ES-MS offers one of the foremost methods for determining compounds in complex aqueous solutions. In this work, LC-ES-MS methods are devised using ion exclusion chromatography, reversed phase chromatography, and ion exchange chromatography, as well as capillary electrophoresis (CE). For an aqueous sample, these LC-ES-MS and CE-ES-MS techniques require no sample preparation or analyte derivatization, which makes it possible to observe a wide variety of analytes as they exist in solution. The majority of this work focuses on the use of LC-ES-MS for the determination of unknown products and intermediates formed during electrochemical incineration (ECI), an experimental waste remediation process. This report contains a general introduction to the project and the general conclusions. Four chapters have been removed for separate processing. Titles are: Chapter 2: Determination of small carboxylic acids by ion exclusion chromatography with electrospray mass spectrometry; Chapter 3: Electrochemical incineration of benzoquinone in aqueous media using a quaternary metal oxide electrode in the absence of a soluble supporting electrolyte; Chapter 4: The determination of electrochemical incineration products of 4-chlorophenol by liquid chromatography-electrospray mass spectrometry; and Chapter 5: Determination of small carboxylic acids by capillary electrophoresis with electrospray mass spectrometry.

Termination of nanoscale zero-valent iron reactivity by addition of bromate as a reducing reactivity competitor

Science.gov (United States)

Mines, Paul D.; Kaarsholm, Kamilla M. S.; Droumpali, Ariadni; Andersen, Henrik R.; Lee, Wontae; Hwang, Yuhoon

2017-09-01

Remediation of contaminated groundwater by nanoscale zero-valent iron (nZVI) is widely becoming a leading environmentally friendly solution throughout the globe. Since a wide range of various nZVI-containing materials have been developed for effective remediation, it is necessary to determine an appropriate way to terminate the reactivity of any nZVI-containing material for a practical experimental procedure. In this study, bimetallic Ni/Fe-NPs were prepared to enhance overall reduction kinetics owing to the catalytic reactivity of nickel on the surface of nZVI. We have tested several chemical strategies in order to terminate nZVI reactivity without altering the concentration of volatile compounds in the solution. The strategies include surface passivation in alkaline conditions by addition of carbonate, and consumption of nZVI by a reaction competitor. Four halogenated chemicals, trichloroethylene, 1,1,1-trichloroethane, atrazine, and 4-chlorophenol, were selected and tested as model groundwater contaminants. Addition of carbonate to passivate the nZVI surface was not effective for trichloroethylene. Nitrate and then bromate were applied to competitively consume nZVI by their faster reduction kinetics. Bromate proved to be more effective than nitrate, subsequently terminating nZVI reactivity for all four of the tested halogenated compounds. Furthermore, the suggested termination method using bromate was successfully applied to obtain trichloroethylene reduction kinetics. Herein, we report the simple and effective method to terminate the reactivity of nZVI by addition of a reducing reactivity competitor.

Synergetic effect of alkaline earth metal oxides and iron oxides on the degradation of hexachlorobenzene and its degradation pathway.

Science.gov (United States)

Su, Guijin; Liu, Yexuan; Huang, Linyan; Shi, Yali; Zhang, Aiqian; Zhang, Lixia; Liu, Wenbin; Gao, Lirong; Zheng, Minghui

2013-01-01

The degradation of hexachlorobenzene (HCB) was carried out over physical mixtures of a series of alkaline earth metal oxides (MO: M=Mg, Ca, Sr, Ba) and iron oxides with different crystal types (Fe(x)O(y):Fe(2)O(3) or Fe(3)O(4)) at 300°C. These physical mixtures all showed a synergetic effect toward the degradation of HCB. A range of degradation products were identified by various methods, including tri- to penta-chlorobenzenes by gas chromatography/mass spectrometry (GC-MS), tri- to penta-chlorophenols, tetrachlorocatechol (TCC) and tetrachlorohydroquinone (TCHQ) by GC-MS after derivatization, and formic and acetic acids by ion chromatography. Two degradation pathways, hydrodechlorination and oxidative degradation, appear to occur competitively. However, more sequential chlorinated benzene and phenol congeners were formed over mixed MO/Fe(3)O(4) than over mixed MO/Fe(2)O(3) under the same conditions. The oxidative reaction dominated over mixed MO/Fe(2)O(3) and was promoted as the major reaction by the synergetic effect, while both the oxidative and hydrodechlorination reactions were important over mixed MO/Fe(3)O(4), and both pathways are remarkably promoted by the synergetic effect. The enhanced hydrodechlorination may be attributed to free electrons generated by the transformation of Fe(3)O(4) into Fe(2)O(3), and hydrogen provided by water adsorbed on the MO. Copyright © 2012 Elsevier Ltd. All rights reserved.

Simultaneous removal of Cr(VI) and 4-chlorophenol through photocatalysis by a novel anatase/titanate nanosheet composite: Synergetic promotion effect and autosynchronous doping

International Nuclear Information System (INIS)

Liu, Wen; Sun, Weiling; Borthwick, Alistair G.L.; Wang, Ting; Li, Fan; Guan, Yidong

2016-01-01

Highlights: • TNS composed of anatase and titanate synthesized via a facile one-step method. • Cr(VI) and 4-CP can be simultaneously removed by TNS through photocatalysis. • Photocatalytic efficiencies of Cr(VI) and 4-CP greatly enhanced when coexisting. • Synergetic promotion effect occurs due to separation of electron-hole pairs. • Autosynchronous doping after Cr(III) adsorption leads to narrowed energy gap. - Abstract: Clean-up of wastewaters with coexisting heavy metals and organic contaminants is a huge issue worldwide. In this study, a novel anatase/titanate nanosheet composite material (labeled as TNS) synthesized through a one-step hydrothermal reaction was demonstrated to achieve the goal of simultaneous removal of Cr(VI) and 4-cholophenol (4-CP) from water. TEM and XRD analyses indicated the TNS was a nano-composite of anatase and titanate, with anatase acting as the primary photocatalysis center and titanate as the main adsorption site. Enhanced photocatalytic removal of co-existent Cr(VI) and 4-CP was observed in binary systems, with apparent rate constants (k_1) for photocatalytic reactions of Cr(VI) and 4-CP about 3.1 and 2.6 times of that for single systems. In addition, over 99% of Cr(VI) and 4-CP was removed within 120 min through photocatalysis by TNS at pH 7 in the binary system. Mechanisms for enhanced photocatalytic efficiency in the binary system are identified as: (1) a synergetic effect on the photo-reduction of Cr(VI) and photo-oxidation of 4-CP due to efficient separation of electron-hole pairs, and (2) autosynchronous doping because of reduced Cr(III) adsorption onto TNS. Furthermore, TNS could be efficiently reused after a simple acid-base treatment.

Simultaneous removal of Cr(VI) and 4-chlorophenol through photocatalysis by a novel anatase/titanate nanosheet composite: Synergetic promotion effect and autosynchronous doping

Energy Technology Data Exchange (ETDEWEB)

Liu, Wen, E-mail: wzl0025@auburn.edu [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Sun, Weiling [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Borthwick, Alistair G.L. [School of Engineering, The University of Edinburgh, The King’s Buildings, Edinburgh EH9 3JL (United Kingdom); Wang, Ting [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Li, Fan [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Guan, Yidong, E-mail: yidongguan@nuist.edu.cn [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States)

2016-11-05

Highlights: • TNS composed of anatase and titanate synthesized via a facile one-step method. • Cr(VI) and 4-CP can be simultaneously removed by TNS through photocatalysis. • Photocatalytic efficiencies of Cr(VI) and 4-CP greatly enhanced when coexisting. • Synergetic promotion effect occurs due to separation of electron-hole pairs. • Autosynchronous doping after Cr(III) adsorption leads to narrowed energy gap. - Abstract: Clean-up of wastewaters with coexisting heavy metals and organic contaminants is a huge issue worldwide. In this study, a novel anatase/titanate nanosheet composite material (labeled as TNS) synthesized through a one-step hydrothermal reaction was demonstrated to achieve the goal of simultaneous removal of Cr(VI) and 4-cholophenol (4-CP) from water. TEM and XRD analyses indicated the TNS was a nano-composite of anatase and titanate, with anatase acting as the primary photocatalysis center and titanate as the main adsorption site. Enhanced photocatalytic removal of co-existent Cr(VI) and 4-CP was observed in binary systems, with apparent rate constants (k{sub 1}) for photocatalytic reactions of Cr(VI) and 4-CP about 3.1 and 2.6 times of that for single systems. In addition, over 99% of Cr(VI) and 4-CP was removed within 120 min through photocatalysis by TNS at pH 7 in the binary system. Mechanisms for enhanced photocatalytic efficiency in the binary system are identified as: (1) a synergetic effect on the photo-reduction of Cr(VI) and photo-oxidation of 4-CP due to efficient separation of electron-hole pairs, and (2) autosynchronous doping because of reduced Cr(III) adsorption onto TNS. Furthermore, TNS could be efficiently reused after a simple acid-base treatment.

Emissions of toxic pollutants from co-combustion of demolition and construction wood and household waste fuel blends.

Science.gov (United States)

Edo, Mar; Ortuño, Núria; Persson, Per-Erik; Conesa, Juan A; Jansson, Stina

2018-07-01

Four different types of fuel blends containing demolition and construction wood and household waste were combusted in a small-scale experimental set-up to study the effect of fuel composition on the emissions of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), chlorobenzenes (PCBzs), chlorophenols (PCPhs) and polycyclic aromatic hydrocarbons (PAHs). Two woody materials, commercial stemwood (ST) and demolition and construction wood (DC) were selected because of the differences in their persistent organic pollutants (POPs), ash and metals content. For household waste, we used a municipal solid waste (MSW) and a refuse-derived fuel (RDF) from MSW with 5-20 wt% and up to 5 wt% food waste content respectively. No clear effect on the formation of pollutants was observed with different food waste content in the fuel blends tested. Combustion of ST-based fuels was very inefficient which led to high PAH emissions (32 ± 3.8 mg/kg fuel ). The use of DC clearly increased the total PCDD and PCDF emissions (71 ± 26 μg/kg fuel ) and had a clear effect on the formation of toxic congeners (210 ± 87 ng WHO 2005 -TEQ/kg fuel ). The high PCDD and PCDF emissions from DC-based fuels can be attributed to the presence of material contaminants such as small pieces of metals or plastics as well as timber treated with chromated copper arsenate preservatives and pentachlorophenol in the DC source. Copyright © 2018 Elsevier Ltd. All rights reserved.

Physical Selectivity of Molecularly Imprinted polymers evaluated through free volume size distributions derived from Positron Lifetime Spectroscopy

Science.gov (United States)

Pasang, T.; Ranganathaiah, C.

2015-06-01

The technique of imprinting molecules of various sizes in a stable structure of polymer matrix has derived multitudes of applications. Once the template molecule is extracted from the polymer matrix, it leaves behind a cavity which is physically (size and shape) and chemically (functional binding site) compatible to the particular template molecule. Positron Annihilation Lifetime Spectroscopy (PALS) is a well known technique to measure cavity sizes precisely in the nanoscale and is not being used in the field of MIPs effectively. This method is capable of measuring nanopores and hence suitable to understand the physical selectivity of the MIPs better. With this idea in mind, we have prepared molecular imprinted polymers (MIPs) with methacrylicacid (MAA) as monomer and EGDMA as cross linker in different molar ratio for three different size template molecules, viz. 4-Chlorophenol (4CP)(2.29 Å), 2-Nephthol (2NP) (3.36 Å) and Phenolphthalein (PP) (4.47Å). FTIR and the dye chemical reactions are used to confirm the complete extraction of the template molecules from the polymer matrix. The free volume size and its distribution have been derived from the measured o-Ps lifetime spectra. Based on the free volume distribution analysis, the percentage of functional cavities for the three template molecules are determined. Percentage of functional binding cavities for 4-CP molecules has been found out to be 70.2% and the rest are native cavities. Similarly for 2NP it is 81.5% and nearly 100% for PP. Therefore, PALS method proves to be very precise and accurate for determining the physical selectivity of MIPs.

Transformation of avobenzone in conditions of aquatic chlorination and UV-irradiation.

Science.gov (United States)

Trebše, Polonca; Polyakova, Olga V; Baranova, Maria; Kralj, Mojca Bavcon; Dolenc, Darko; Sarakha, Mohamed; Kutin, Alexander; Lebedev, Albert T

2016-09-15

Emerging contaminants represent a wide group of the most different compounds. They appear in the environment at trace levels due to human activity. Most of these compounds are not yet regulated. Sunscreen UV-filters play an important role among these emerging contaminants. In the present research the reactions of 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone), the most common UV filter in the formulation of sunscreens, were studied under the combined influence of active chlorine and UV-irradiation. Twenty five compounds were identified by GC/MS as transformation products of avobenzone in reactions of aquatic UV-irradiation and chlorination with sodium hypochlorite. A complete scheme of transformation of avobenzone covering all the semivolatile products is proposed. The identification of the two primary chlorination products (2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione) was confirmed by their synthesis and GC/MS and NMR analysis. Although the toxicities of the majority of these products remain unknown substituted chlorinated phenols and acetophenones are known to be rather toxic. Combined action of active chlorine and UV-irradiation results in the formation of some products (chloroanhydrides, chlorophenols) not forming in conditions of separate application of these disinfection methods. Therefore caring for people «well-being» it is of great importance to apply the most appropriate disinfection method. Since the primary transformation products partially resist powerful UV-C irradiation they may be treated as stable and persistent pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Direct in situ activation of Ag{sup 0} nanoparticles in synthesis of Ag/TiO{sub 2} and its photoactivity

Energy Technology Data Exchange (ETDEWEB)

Jaafar, N.F. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Jalil, A.A., E-mail: aishah@cheme.utm.my [Institute of Hydrogen Economy, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Efendi, J. [Department of Chemistry, Universitas Negeri Padang, Jl. Prof. Hamka, Air Tawar, Padang, West Sumatera (Indonesia); Mukti, R.R. [Division of Inorganic and Physical Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl Ganesha No. 10, Bandung 40132 (Indonesia); Jusoh, R.; Jusoh, N.W.C. [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Karim, A.H. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Salleh, N.F.M. [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Suendo, V. [Division of Inorganic and Physical Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl Ganesha No. 10, Bandung 40132 (Indonesia)

2015-05-30

Graphical abstract: - Highlights: • Ag{sup 0} loaded on TiO{sub 2} was prepared by a direct in situ electrochemical method. • 5 wt% Ag–TiO{sub 2} demonstrated the best photocatalytic degradation of 2-CP. • Isomorphous substitution of Ag with Ti occurred to form Ti−O−Ag bonds. • Ag{sup 0} and oxygen vacancies trapped electrons to enhance e–H{sup +} separation. • Substitution of Ag in the TiO{sub 2} structure decreased the number of oxygen vacancies. - Abstract: Metallic Ag nanoparticles (Ag{sup 0}) were successfully activated using a direct in situ electrochemical method before being supported on TiO{sub 2}. Catalytic testing showed that 5 wt% Ag–TiO{sub 2} gave the highest photodegradation (94%) of 50 mg L{sup −1} 2-chlorophenol (2-CP) at pH 5 using 0.375 g L{sup −1} catalyst within 6 h, while under similar conditions, 1 wt% and 10 wt% Ag–TiO{sub 2} only gave 75% and 78% degradation, respectively. Characterization results illustrated that the photoactivity was affected by the amount of Ag{sup 0} and oxygen vacancies which act as an electrons trap to enhance the electron–hole separation. While, the Ag−O−Ti bonds formation reduced the photoactivity. The degradation followed a pseudo-first order Langmuir–Hinshelwood model where adsorption was the controlling step. Study on the effect of scavengers showed that the hole (H{sup +}) and hydroxyl radical (OH·) play important roles in the photodegradation. The regenerated photocatalyst was still stable after five cycling runs.

The levels of polychlorinated biphenyls in 1,4-dichlorobenzene mothballs

Energy Technology Data Exchange (ETDEWEB)

Liu, Wenbin; Zheng, Minghui; Xing, Ying; Wang, Dongshen; Zhao, Xingru; Gao, Lirong [Chinese Academy of Sciences, Beijing (China). Key laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences

2004-09-15

The chemical 1,4-dichlorobenzene (p-DCB), also called paramoth, is one of the chemicals commonly used to make mothballs. For the more than 20 years, p-DCB has been used principally (35-55% of all uses) as a space deodorant for toilets and refuse containers, and as a fumigant for control of moths, molds, and mildews. The process of production of p-DCB currently used by industry is direct chlorination of benzene or chlorobenzene in the presence of a Friedel-Crafts catalyst (typically FeCl{sub 3}), and the pure products of p-DCB are obtained by distillation and crystallization from the mixture of polychlorinated benzenes. This process is similar to that of production of PCBs which were manufactured commercially by the progressive chlorination of biphenyl in the presence of a suitable catalyst, e.g., iron chloride. However, few studies on the formation of PCBs from chlorobenzenes have been published. Buser reported significant quantities of PCDFs and a small amount of PCDDs, PCBs, and chlorophenols were formed in the pyrolysis of chlorobenzenes at 620 C. Peng-Yan Liu et al. revealed that lower chlorinated benzenes produce more PCBs than higher ones. Nevertheless, prior to this study, no reports on PCBs in p-DCB and the restriction of PCBs in p-DCB products have been found. In this paper, the occurrence and distribution of dioxin-like PCBs and total PCBs in some commercial p-DCB mothballs are investigated. Except of the toxic of p-DCB, the low concentration of PCBs in p-DCB mothballs should not be negligible.

Accelerated redox reaction between chromate and phenolic pollutants during freezing.

Science.gov (United States)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-05-05

The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at -20°C) was compared with the corresponding reaction in water (i.e., at 25°C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV-vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions. Copyright © 2017 Elsevier B.V. All rights reserved.

Hodgkin's disease, work, and the environment. A review.

Science.gov (United States)

McCunney, R J

1999-01-01

Hodgkin's disease (HD), a lymphoma with an annual incidence in the United States of approximately 7500 cases, primarily affects the lymph nodes, spleen, and liver. The point of this article is to critically review the literature regarding the purported relationships between HD, certain occupations, and exposure to chemical agents. Attention will also be focused on recent advances in molecular genetics in the etiology of this ailment. A MEDLINE search was conducted to assess case-control and mortality evaluations that investigated links between HD and certain occupations and exposure to designated hazards. A review of citations in the Silver Platter Occupational and Environmental Medicine CD-ROM database was also conducted to ensure that all pertinent reports were obtained. Of the industries evaluated, woodworking showed the most consistent link between an increased risk of HD (relative risk, 1.8 to 7.2), but not all studies conducted showed positive associations. Although certain chemicals (ie, chlorophenols, pesticides) were reported as risks, no chemical was consistently and unambiguously linked with HD. Recent investigative work, however, points to a major etiological role for the Epstein-Barr virus (EBV), genetic fragments of which have been noted in Reed-Sternberg cells, the classic malignant cells of HD. The occupation most consistently associated with HD appears to be woodworking, although no specific chemical has been consistently linked with this lymphoma. The most persuasive evidence regarding the cause of HD arises from recent studies, including epidemiological, clinical, and genetic studies, that point to a major role by the EBV.

Characterising boiler ash from a circulating fluidised bed municipal solid waste incinerator and distribution of PCDD/F and PCB.

Science.gov (United States)

Zhang, Mengmei; Buekens, Alfons; Li, Xiaodong

2018-05-31

In this study, ash samples were collected from five locations situated in the boiler of a circulating fluidised bed municipal solid waste incinerator (high- and low-temperature superheater, evaporator tubes and upper and lower economiser). These samples represent a huge range of flue gas temperatures and were characterised for their particle size distribution, surface characteristics, elemental composition, chemical forms of carbon and chlorine and distribution of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB). Enrichment of chlorine, one of the main elements of organochlorinated pollutants, and copper, zinc and lead, major catalytic metals for dioxin-like compounds, was observed in lower-temperature ash deposits. The speciation of carbon and chlorine on ash surfaces was established, showing a positive correlation between organic chlorine and oxygen-containing carbon functional groups. The load of PCDD/F and PCB (especially dioxin-like PCB) tends to rise rapidly with falling temperature of flue gas, reaching their highest value in economiser ashes. The formation of PCDD/F congeners through the chlorophenol precursor route apparently was enhanced downstream the boiler. Principal component analysis (PCA) was applied to study the links between the ash characteristics and distribution of chloro-aromatics. The primary purpose of this study is improving the understanding of any links between the characteristics of ash from waste heat systems and its potential to form PCDD/F and PCB. The question is raised whether further characterisation of fly ash may assist to establish a diagnosis of poor plant operation, inclusive the generation, destruction and eventual emission of persistent organic pollutants (POPs).

Separation science and technology

International Nuclear Information System (INIS)

Smith, B.F.; Sauer, N.; Chamberlin, R.M.; Gottesfeld, S.; Mattes, B.R.; Li, D.Q.; Swanson, B.

1998-01-01

The focus of this project is the demonstration and advancement of membrane-based separation and destruction technologies. The authors are exploring development of membrane systems for gas separations, selective metal ion recovery, and for separation or destruction of hazardous organics. They evaluated existing polymers and polymer formulations for recovery of toxic oxyanionic metals such as chromate and arsenate from selected waste streams and developed second-generation water-soluble polymeric systems for highly selective oxyanion removal and recovery. They optimized the simultaneous removal of radioactive strontium and cesium from aqueous solutions using the new nonhazardous separations agents, and developed recyclable, redox-active extractants that permitted recovery of the radioactive ions into a minimal waste volume. They produced hollow fibers and fabricated prototype hollow-fiber membrane modules for applications to gas separations and the liquid-liquid extraction and recovery of actinides and nuclear materials from process streams. They developed and fabricated cyclodextrin-based microporous materials that selectively absorb organic compounds in an aqueous environment; the resultant products gave pure water with organics at less than 0.05 parts per billion. They developed new, more efficient, membrane-based electrochemical reactors for use in organic destruction in process waste treatment. They addressed the need for advanced oxidation technologies based on molecular-level materials designs that selectively remove or destroy target species. They prepared and characterized surface-modified TiO 2 thin films using different linking approaches to attach ruthenium photosensitizers, and they started the measurement of the photo-degradation products generated using surface modified TiO 2 films in reaction with chlorophenol

Hydrothermal synthesis of Ca3Bi8O15 rods and their visible light photocatalytic properties

International Nuclear Information System (INIS)

Li, Wenjuan; Kong, Desheng; Cui, Xiaoli; Du, Dandan; Yan, Tingjiang; You, Jinmao

2014-01-01

Graphical abstract: The novel Ca 3 Bi 8 O 15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. - Highlights: • Ca 3 Bi 8 O 15 rods were synthesized by a hydrothermal method. • They can utilize the sunlight efficiently with the small band-gap. • They showed good photocatalytic activities in the degradation of MO, RhB and 4-CP. • The conversion ratio of MO was up to 90% after 2 h of visible light irradiation. - Abstract: High efficient visible light Ca 3 Bi 8 O 15 photocatalysts were synthesized by a hydrothermal method. Characterized by X-ray diffractometer, transmission electron microscopy, and the UV–vis diffuse reflectance spectroscopy, the results showed that the novel Ca 3 Bi 8 O 15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. Furthermore, they also showed good photocatalytic activities in the degradation of rhodamine B and p-chlorophenol. Through the investigation of the degraded mechanism, the main active species played important roles in the degradation process were holes, O 2 · − and ·OH

Electrochemical destruction of chlorophenoxy herbicides by anodic oxidation and electro-Fenton using a boron-doped diamond electrode

International Nuclear Information System (INIS)

Brillas, Enric; Boye, Birame; Sires, Ignasi; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Arias, Conchita; Cabot, Pere-Lluis; Comninellis, Christos

2004-01-01

The degradation of herbicides 4-chlorophenoxyacetic acid (4-CPA), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous medium of pH 3.0 has been comparatively studied by anodic oxidation and electro-Fenton using a boron-doped diamond (BDD) anode. All solutions are totally mineralized by electro-Fenton, even at low current, being the process more efficient with 1 mM Fe 2+ as catalyst. This is due to the production of large amounts of oxidant hydroxyl radical (OH·) on the BDD surface by water oxidation and from Fenton's reaction between added Fe 2+ and H 2 O 2 electrogenerated at the O 2 -diffusion cathode. The herbicide solutions are also completely depolluted by anodic oxidation. Although a quicker degradation is found at the first stages of electro-Fenton, similar times are required for achieving overall mineralization in both methods. The decay kinetics of all herbicides always follows a pseudo first-order reaction. Reversed-phase chromatography allows detecting 4-chlorophenol, 4-chloro-o-cresol, 2,4-dichlorophenol and 2,4,5-trichlorophenol as primary aromatic intermediates of 4-CPA, MCPA, 2,4-D and 2,4,5-T, respectively. Dechlorination of these products gives Cl - , which is slowly oxidized on BDD. Ion-exclusion chromatography reveals the presence of persistent oxalic acid in electro-Fenton by formation of Fe 3+ -oxalato complexes, which are slowly destroyed by OH· adsorbed on BDD. In anodic oxidation, oxalic acid is mineralized practically at the same rate as generated

Semi-pilot Scale Environment Friendly Photocatalytic Degradation of 4-Chlorophenol with Singlet Oxygen Species - Direct Comparison with H2O2/UV-C Reaction System

Czech Academy of Sciences Publication Activity Database

Krystyník, Pavel; Klusoň, Petr; Hejda, S.; Bůžek, D.; Mašín, P.; Tito, D.N.

2014-01-01

Roč. 160, NOV (2014), s. 506-513 ISSN 0926-3373 R&D Projects: GA TA ČR TA03010548 Institutional support: RVO:67985858 Keywords : phthalocyanine * photochemical oxidation * hydrogen peroxide Subject RIV: JI - Composite Materials Impact factor: 7.435, year: 2014

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.

Facile synthesis of ZnO/CuInS{sub 2} nanorod arrays for photocatalytic pollutants degradation

Energy Technology Data Exchange (ETDEWEB)

Yang, Yawei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Zhang, Xinyu [Frontier Institute of Science and Technology Jointly with College of Science, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Xing, Yonglei; Yin, Xingtian [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic & Information Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Du, Yaping, E-mail: ypdu2013@mail.xjtu.edu.cn [Frontier Institute of Science and Technology Jointly with College of Science, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China)

2016-11-05

Highlights: • Vertically-aligned ZnO nanorod arrays were synthesized by the hydrothermal process. • Monodisperse CuInS{sub 2} QDs were synthesized by the one-pot colloidal chemistry method. • ZnO/CuInS{sub 2} nanorod arrays films were fabricated by the EPD process. • The homogeneous CuInS{sub 2} loading was optimized by EPD duration. • The photoelectrochemical and photocatalytic activities of the ZnO/CuInS{sub 2} nanorod arrays films were discussed. - Abstract: Vertically-aligned ZnO nanorod arrays on a fluorine-doped tin oxide glass substrate were homogeneously coated with visible light active CuInS{sub 2} quantum dots by using a controllable electrophoretic deposition strategy. Compared with the pure ZnO nanorod arrays, the formation of high-quality ZnO/CuInS{sub 2} heterojunction with well-matched band energy alignment expanded the light absorption from ultraviolet to visible region and facilitated efficient charge separation and transportation, thus yielding remarkable enhanced photoelectrochemical performance and photocatalytic activities for methyl orange and 4-chlorophenol degradation. The ZnO/CuInS{sub 2} film with the deposition duration of 80 min showed the highest degradation rate and photocurrent density (0.95 mA/cm{sup 2}), which was almost 6.33 times higher than that of the pure ZnO nanorod arrays film. The CuInS{sub 2} QDs sensitized ZnO nanorod arrays film was proved to be a superior structure for photoelectrochemical and photocatalytic applications due to the optimized CuInS{sub 2} loading and well-maintained one-dimensional nanostructure.

Electrochemical degradation of clofibric acid in water by anodic oxidation

International Nuclear Information System (INIS)

Sires, Ignasi; Cabot, Pere Lluis; Centellas, Francesc; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Arias, Conchita; Brillas, Enric

2006-01-01

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 (·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 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 ·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 2 with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed

Ammonia-modified graphene sheets decorated with magnetic Fe{sub 3}O{sub 4} nanoparticles for the photocatalytic and photo-Fenton degradation of phenolic compounds under sunlight irradiation

Energy Technology Data Exchange (ETDEWEB)

Boruah, Purna K. [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Academy of Scientific and Innovative Research (AcSIR) (India); Sharma, Bhagyasmeeta [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Karbhal, Indrapal; Shelke, Manjusha V. [Academy of Scientific and Innovative Research (AcSIR) (India); Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune-11008, Maharashtra (India); Das, Manash R., E-mail: mnshrdas@yahoo.com [Advanced Materials Group, Materials Sciences and Technology Division, CSIR-North East Institute of Science & Technology, Jorhat 785006 (India); Academy of Scientific and Innovative Research (AcSIR) (India)

2017-03-05

Highlights: • Ammonia-modified graphene sheets decorated with magnetic Fe{sub 3}O{sub 4} nanoparticles. • Photocatalytic and photo-Fenton degradation of phenolic compounds. • An excellent reusability of the nanocomposite was observed up to ten cycles. - Abstract: Synthesis of easily separable and eco-friendly efficient catalyst with both photocatalytic and photo-Fenton degradation properties is of great importance for environment remediation application. Herein, ammonia-modified graphene (AG) sheets decorated with Fe{sub 3}O{sub 4} nanoparticles (AG/Fe{sub 3}O{sub 4}) as a magnetically recoverable photocatalyst by a simple in situ solution chemistry approach. First, we have functionalized graphene oxide (GO) sheets by amide functional group and then Fe{sub 3}O{sub 4} nanoparticles (NPs) are doped onto the functionalized GO surface. The AG/Fe{sub 3}O{sub 4} nanocomposite showed efficient photocatalytic activity towards degradation of phenol (92.43%), 2-nitrophenol (2-NP) (98%) and 2-chlorophenol (2-CP) (97.15%) within 70–120 min. Consequently, in case of photo-Fenton degradation phenomenon, 93.56% phenol, 98.76% 2-NP and 98.06% of 2-CP degradation were achieved within 50–80 min using AG/Fe{sub 3}O{sub 4} nanocomposite under sunlight irradiation. The synergistic effect between amide functionalized graphene and Fe{sub 3}O{sub 4} nanoparticles (NPs) enhances the photocatalytic activity by preventing the recombination rate of electron-hole-pair in Fe{sub 3}O{sub 4} NPs. Furthermore, the remarkable reusability of the AG/Fe{sub 3}O{sub 4} nanocomposite was observed up to ten cycles during the photocatalytic degradation of these phenolic compounds.

Cleavage and synthesis function of high and low redox potential laccases towards 4-morpholinoaniline and aminated as well as chlorinated phenols.

Science.gov (United States)

Hahn, Veronika; Mikolasch, Annett; Schauer, Frieder

2014-02-01

Laccases are able to mediate both cleavage and synthesis processes. The basis for this dual reaction capability lies in the property of the enzyme laccase to oxidize phenolic, and to some extent non-phenolic substances, to reactive radicals which can undergo on the one hand separations of small substitutents or large molecule parts from the parent compound and on the other hand coupling reactions with other radicals or molecules which are not themselves oxidizable by laccase. The cleavage of the non-phenolic compound 4-morpholinoaniline as well as the deamination of 4-aminophenol and the dechlorination of 4-chlorophenol resulted in the formation of 1,4-hydroquinone which is immediately oxidized by laccase to 1,4-benzoquinone. The formation of the 1,4-hydroquinone/1,4-benzoquinone is the rate limiting step for the synthesis of the heteromolecular dimers and trimers composed of 1,4-benzoquinone and one or two molecules of morpholine. In addition to the synthesis of new compounds from the cleavage products, 4-morpholinoaniline polymerized probably via azo groups and C-N bonds to a homomolecular dimer and trimer. Similarities and differences in cleavage and synthesis reactions catalyzed by the low redox potential laccase of Myceliophthora thermophila (0.46 V) and the high redox potential laccase of Pycnoporus cinnabarinus (0.79 V) were determined. In addition, the dependency of the cleavage and synthesis efficiencies on the (a) structure and redox potential of the laccase, (b) structure and redox potential of the substrate, (c) pH value of the buffer used, (d) incubation temperature, (e) solvent concentration, and (f) laccase activity is discussed in general.

Green synthesis of NiO nanoparticles using Aegle marmelos leaf extract for the evaluation of in-vitro cytotoxicity, antibacterial and photocatalytic properties.

Science.gov (United States)

Angel Ezhilarasi, A; Judith Vijaya, J; Kaviyarasu, K; John Kennedy, L; Ramalingam, R Jothi; Al-Lohedan, Hamad A

2018-03-01

In the present study, we report the green synthesis of NiO nanoparticles using Aegle marmelos as a fuel and this method is ecofriendly and cost effective. The plant Aegle marmelos is used in the field of pharmaceuticals to cure diseases like chronic diarrhea, peptic ulcers and dysentery in India for nearly 5 centuries. The as-prepared nanoparticles were confirmed as pure face centered cubic phase and single crystalline in nature by XRD. The formation of agglomerated spherical nanoparticles was shown by HR-SEM and HR-TEM images. The particle size calculated from HR-SEM was in the range 8-10 nm and it matches with the average crystallite size calculated from the XRD pattern. NiO shows intense emission peaks at 363 and 412 nm in its PL spectra. The band gap of 3.5 eV is observed from DRS studies and the formation of pure NiO is confirmed by FT-IR spectra. The as-prepared NiO nanoparticles show super paramagnetic behavior, when magnetization studies are carried out. It is then evaluated for cytotoxic activity towards A549 cell culture, antibacterial activity and photocatalytic degradation (PCD) of 4‑chlorophenol (4‑CP), which is known as the endocrine disrupting chemical (EDC). From the results, it is found that the cell viability of A549 cells was effectively reduced and it showed better antibacterial activity towards gram positive bacterial strains. It is also proved to be an efficient and stable photocatalyst towards the degradation of 4‑CP. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation and characterization of PbO2–ZrO2 nanocomposite electrodes

International Nuclear Information System (INIS)

Yao Yingwu; Zhao Chunmei; Zhu Jin

2012-01-01

PbO 2 –ZrO 2 nanocomposite electrodes were prepared by the anodic codeposition in the lead nitrate plating bath containing ZrO 2 nanoparticles. The influences of the ZrO 2 nanoparticles concentration, current density, temperature and stirring rate of the plating bath on the composition of the nanocomposite electrodes were investigated. The surface morphology and the structure of the nanocomposite electrodes were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD), respectively. The experimental results show that the addition of ZrO 2 nanoparticles in the electrodeposition process of lead dioxide significantly increases the lifetime of nanocomposite electrodes. The PbO 2 –ZrO 2 nanocomposite electrodes have a service life of 141 h which is almost four times longer than that of the pure PbO 2 electrodes. The morphology of PbO 2 –ZrO 2 nanocomposite electrodes is more compact and finer than that of PbO 2 electrodes. The relative surface area of the composite electrodes is approximately 2 times that of the pure PbO 2 electrodes. The structure test shows that the addition of ZrO 2 nanoparticles into the plating bath decreases the grain size of the PbO 2 –ZrO 2 nanocomposite electrodes. The anodic polarization curves show that the oxygen evolution overpotential of PbO 2 –ZrO 2 nanocomposite electrodes is higher than PbO 2 electrodes. The pollutant anodic oxidation experiment show that the PbO 2 –ZrO 2 nanocomposite electrode exhibited the better performance for the degradation of 4-chlorophenol than PbO 2 electrode, the removal ratio of COD reached 96.2%.

Photobiodegradation of chlorinated water pollutants by a combined TiO2-polyaniline-enzyme catalytic system

Science.gov (United States)

Campanella, Luigi; Crescentini, G.; Militerno, S.

1995-10-01

The removal of xenobiotic compounds, such as chlorophenols and pesticides, from municipal and industrial wastewaters is an important task because of the toxicity and the tendency to bioaccumulation of these compounds. Among the several methods proposed, photodegradation catalyzed by suspended inorganic semiconductors (i.e. TiO2) has lately received wide attention because this process is fast, leads to non-toxic final products and shows a high degradation efficiency. In this work, the results obtained in the photodegradation of monochlorophenols using a new catalyst, made of TiO2 and polyaniline both immobilized on a polyvinylchloride (PVC) membrane, in presence (and in absence) of an enzyme are presented. Different enzymes have been tested by adding 5, 10 or 15 U/mL to 50 mL of aqueous solution (1 multiplied by 10-4 mol/L) of o-chloro-phenol containing the catalytic membrane. The samples were irradiated using a QUV panel accelerated weathering tester, which simulates very well the solar radiation up to lambda equals 400 nm and HPLC was used to measure the variation of the compound's concentration with the time. While some enzymes (i.e., peroxidase) do not improve the photodegradation process since they do not survive under the irradiation conditions used, some of them show marked effect both in terms of rate degradation and time required to reach the total degradation of the compound examined. For example, the addition of Laccase reduces the 100% degradation time from 35 hrs to about 20 hrs. Attempts to immobilize the enzyme on the catalytic membrane (by adsorption) have been carried out and the performance of the catalyst with non-immobilized and immobilized enzyme has been studied.

Unprecedented access of phenolic substrates to the heme active site of a catalase: substrate binding and peroxidase-like reactivity of Bacillus pumilus catalase monitored by X-ray crystallography and EPR spectroscopy.

Science.gov (United States)

Loewen, Peter C; Villanueva, Jacylyn; Switala, Jacek; Donald, Lynda J; Ivancich, Anabella

2015-05-01

Heme-containing catalases and catalase-peroxidases catalyze the dismutation of hydrogen peroxide as their predominant catalytic activity, but in addition, individual enzymes support low levels of peroxidase and oxidase activities, produce superoxide, and activate isoniazid as an antitubercular drug. The recent report of a heme enzyme with catalase, peroxidase and penicillin oxidase activities in Bacillus pumilus and its categorization as an unusual catalase-peroxidase led us to investigate the enzyme for comparison with other catalase-peroxidases, catalases, and peroxidases. Characterization revealed a typical homotetrameric catalase with one pentacoordinated heme b per subunit (Tyr340 being the axial ligand), albeit in two orientations, and a very fast catalatic turnover rate (kcat  = 339,000 s(-1) ). In addition, the enzyme supported a much slower (kcat  = 20 s(-1) ) peroxidatic activity utilizing substrates as diverse as ABTS and polyphenols, but no oxidase activity. Two binding sites, one in the main access channel and the other on the protein surface, accommodating pyrogallol, catechol, resorcinol, guaiacol, hydroquinone, and 2-chlorophenol were identified in crystal structures at 1.65-1.95 Å. A third site, in the heme distal side, accommodating only pyrogallol and catechol, interacting with the heme iron and the catalytic His and Arg residues, was also identified. This site was confirmed in solution by EPR spectroscopy characterization, which also showed that the phenolic oxygen was not directly coordinated to the heme iron (no low-spin conversion of the Fe(III) high-spin EPR signal upon substrate binding). This is the first demonstration of phenolic substrates directly accessing the heme distal side of a catalase. © 2015 Wiley Periodicals, Inc.

Tentacle carrier for immobilization of potato phenoloxidase and its application for halogenophenols removal from aqueous solutions

International Nuclear Information System (INIS)

Lončar, Nikola; Vujčić, Zoran

2011-01-01

Highlights: ► We synthesized novel immobilization carrier from reused DEAE-cellulose. ► We used it for immobilization of PPO through coordinative bonding with copper ions. ► Immobilized PPO showed better characteristics than soluble PPO. ► TC-PPO removed over 90% of halogenophenols at concentration of 100 mg/L. - Abstract: Halogenated compounds represent one of the most dangerous environmental pollutants, due to their widespread usage as biocides, fungicides, disinfectants, solvent and other industrial chemicals. Immobilization of a protein through coordinate bonds formed with divalent metal ions is becoming an attractive method due to its reversible nature, since the protein may be easily removed from the support matrix through interruption of the protein–metal bond hence giving inherently cleaner and cheaper technology for wastewater treatment. We have synthesized novel ‘tentacle’ carrier (TC) and used it for immobilization of partially purified potato polyphenol oxidase (PPO). The obtained biocatalyst TC-PPO showed pH optimum at 7.0–8.0 and temperature optimum at 25 °C. Immobilized PPO shows almost 100% of activity at 0 °C. TC-PPO was more resistant to the denaturation induced by sodium dodecyl sulphate (SDS) detergent as compared to its soluble counterpart and was even slightly activated at SDS concentration of 1%. TC-PPO was tested in the batch reactor for 4-chlorophenol and 4-bromophenol removal. More than 90% removal was achieved for both halogenophenols at concentration of 100 mg/L from aqueous solution. For both halogenophenols TC-PPO works with over 90% removal during first three cycles which decrease to 60% removal efficiency after six cycles each of 8 h duration.

Self-floating graphitic carbon nitride/zinc phthalocyanine nanofibers for photocatalytic degradation of contaminants

Energy Technology Data Exchange (ETDEWEB)

Xu, Tiefeng; Ni, Dongjing; Chen, Xia; Wu, Fei; Ge, Pengfei; Lu, Wangyang, E-mail: luwy@zstu.edu.cn; Hu, Hongguang; Zhu, ZheXin; Chen, Wenxing, E-mail: wxchen@zstu.edu.cn

2016-11-05

Highlights: • A facile synthetic strategy to prepare visible-light responsive electrospun nanofibers. • Self-floating nanofiber photocatalyts for the effective utilization of solar. • Possible degradation pathway of RhB and CBZ under visible light and solar irradiation. • Present a method for removing highly hazardous contaminants. - Abstract: The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C{sub 3}N{sub 4}/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C{sub 3}N{sub 4}/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C{sub 3}N{sub 4}/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules.

Theoretical perspectives on the mechanism and kinetics of the OH radical-initiated gas-phase oxidation of PCB126 in the atmosphere

International Nuclear Information System (INIS)

Dang, Juan; Shi, Xiangli; Zhang, Qingzhu; Wang, Wenxing

2015-01-01

Polychlorinated biphenyls (PCBs) primarily exist in the gas phase in air and may undergo atmospheric oxidation degradations, particularly the oxidation reaction initiated by OH radicals. In this work, the mechanism of the OH radical-initiated atmospheric oxidation of the most toxic PCB congener 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) was investigated by using quantum chemistry methods. The rate constants of the crucial elementary reactions were estimated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The oxidation products of the reaction of PCB126 with OH radicals include 3,3′,4,4′,5-pentachlorobiphenyl-ols, chlorophenols, 2,3,4,7,8-pentachlorodibenzofuran, 2,3,4,6,7-pentachlorodibenzofuran, dialdehydes, 3,3′,4,4′,5-pentachloro-5′-nitro-biphenyl, and 4,5-dichloro-2-nitrophenol. Particularly, the formation of polychlorinated dibenzofurans (PCDFs) from the atmospheric oxidation of PCBs is revealed for the first time. The overall rate constant of the OH addition reaction is 2.52 × 10 −13 cm 3 molecule −1 s −1 at 298 K and 1 atm. The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days which indicates that PCB126 can be transported long distances from local to global scales. - Highlights: • A comprehensive mechanism of OH-initiated oxidation of PCB126 was investigated. • The formation of PCDFs from the oxidation of PCBs is determined for the first time. • The rate constants for key elementary reactions were estimated by the RRKM theory. • The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days

A simple and fast method based on mixed hemimicelles coated magnetite nanoparticles for simultaneous extraction of acidic and basic pollutants.

Science.gov (United States)

Asgharinezhad, Ali Akbar; Ebrahimzadeh, Homeira

2016-01-01

One of the considerable and disputable areas in analytical chemistry is a single-step simultaneous extraction of acidic and basic pollutants. In this research, a simple and fast coextraction of acidic and basic pollutants (with different polarities) with the aid of magnetic dispersive micro-solid phase extraction based on mixed hemimicelles assembly was introduced for the first time. Cetyltrimethylammonium bromide (CTAB)-coated Fe3O4 nanoparticles as an efficient sorbent was successfully applied to adsorb 4-nitrophenol and 4-chlorophenol as two acidic and chlorinated aromatic amines as basic model compounds. Using a central composite design methodology combined with desirability function approach, the optimal experimental conditions were evaluated. The opted conditions were pH = 10; concentration of CTAB = 0.86 mmol L(-1); sorbent amount = 55.5 mg; sorption time = 11.0 min; no salt addition to the sample, type, and volume of the eluent = 120 μL methanol containing 5% acetic acid and 0.01 mol L(-1) HCl; and elution time = 1.0 min. Under the optimum conditions, detection limits and linear dynamic ranges were achieved in the range of 0.05-0.1 and 0.25-500 μg L(-1), respectively. The percent of extraction recoveries and relative standard deviations (n = 5) were in the range of 71.4-98.0 and 4.5-6.5, respectively. The performance of the optimized method was certified by coextraction of other acidic and basic compounds. Ultimately, the applicability of the method was successfully confirmed by the extraction and determination of the target analytes in various water samples, and satisfactory results were obtained.

Understanding the role of manganese dioxide in the oxidation of phenolic compounds by aqueous permanganate.

Science.gov (United States)

Jiang, Jin; Gao, Yuan; Pang, Su-Yan; Lu, Xue-Ting; Zhou, Yang; Ma, Jun; Wang, Qiang

2015-01-06

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Pollutant removal-oriented yeast biomass production from high-organic-strength industrial wastewater: A review

International Nuclear Information System (INIS)

Yang, Min; Zheng, Shaokui

2014-01-01

Microbial single-cell-protein (SCP) production from high-organic-strength industrial wastewaters is considered an attractive method for both wastewater purification and resource utilization. In the last two decades, pollutant removal-oriented yeast SCP production processes, i.e., yeast treatment processes, have attracted a great deal of attention from a variety of research groups worldwide. Different from conventional SCP production processes, yeast treatment processes are characterized by higher pollutant removal rates, lower production costs, highly adaptive yeast isolates from nature, no excess nutrient supplements, and are performed under non-sterile conditions. Furthermore, yeast treatment processes are similar to bacteria-dominated conventional activated sludge processes, which offer more choices for yeast SCP production and industrial wastewater treatment. This review discusses why highly adaptive yeast species isolated from nature are used in the yeast treatment process rather than commercial SCP producers. It also describes the application of yeast treatment processes for treating high-carboxyhydrate, oil-rich and high-salinity industrial wastewater, focusing primarily on high-strength biodegradable organic substances, which usually account for the major fraction of biochemical oxygen demand. Also discussed is the biodegradation of xenobiotics, such as color (including dye and pigment) and toxic substances (including phenols, chlorophenols, polycyclic aromatic hydrocarbons, etc.), present in industrial wastewater. Based on molecular information of yeast community structures and their regulation in yeast treatment systems, we also discuss how to maintain efficient yeast species in yeast biomass and how to control bacterial and mold proliferation in yeast treatment systems. - Highlights: • Pollutant removal-oriented yeast SCP production processes offer more choices. • Highly adaptive yeast isolates replace commercial SCP producers. • Yeasts degrade

Development of a cellular biosensor for the detection of 2,4,6-trichloroanisole (TCA).

Science.gov (United States)

Varelas, Vassileios; Sanvicens, Nuria; M-Pilar-Marco; Kintzios, Spiridon

2011-05-15

2,4,6-trichloroanisole (TCA) is a microbial metabolite formed from chlorophenols through the activity of several natural fungal strains present on the cork oak bark. TCA is the primary compound responsible for the mousty/mould off-odour known as "cork taint" present in cork stoppers, wine, water and alcoholic beverages. Chromatographic and electrochemical methods are currently used for the determination of TCA, however its detection at low concentrations remains a technical challenge. The aim of this study was the development of a rapid novel biosensor system based on the Bioelectric Recognition Assay (BERA). The sensor measured the electric response of cultured membrane-engineered fibroblast cells suspended in an alginate gel matrix due to the change of their membrane potential in the presence of the analyte. Membrane-engineered cells were prepared by osmotic insertion of 0.5 μg/l of specific TCA antibodies into the membrane of the cells. The BERA-based sensor was able to detect TCA in a few minutes (3-5 min) at extremely low concentrations (10(-1)ppt), thus demonstrating higher sensitivity than the human sensory threshold. In addition, the assay was quite selective against other haloanisoles and halophenols structurally related to or co-occurring with TCA. Finally the sensor was tested against real white wine samples from cork soaks. At this real test, the BERA sensor was able to detect TCA from cork soaks rapidly (3-5 min) at very low concentrations (1.02-12 ng/l), covering the whole range for the detection threshold for wines (1.4-10 ng/l). Therefore, this novel biosensor offers new perspectives for ultra-rapid, ultra-sensitive and low-cost monitoring of TCA presence in cork and wine and possibly also other food commodities. Copyright © 2011 Elsevier B.V. All rights reserved.

Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

Energy Technology Data Exchange (ETDEWEB)

Gao, Juanjuan; Liu, Maoxiang [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Song, Haiou, E-mail: songhaiou2011@126.com [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Zhang, Shupeng, E-mail: shupeng_2006@126.com [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Qian, Yueyue [School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Li, Aimin, E-mail: liaimin@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

2016-11-15

Highlights: • Phenol detection based on coupled cMWCNT/CD edge-functionalized graphene composite. • Increased conductivity can inspire enhancement of electrocatalytic performance. • The synergistic combination of the trace amounts of CDs and cMWCNT is a pivotal. • GN-CD-cMWCNT shows an excellent electrocatalytic and anti-interference ability. - Abstract: Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027 μM (S/N = 3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

Study of the mechanism of acetonitrile stacking and its application for directly combining liquid-phase microextraction with micellar electrokinetic chromatography.

Science.gov (United States)

Sun, Jingru; Feng, Jing; Shi, Ludi; Liu, Laping; He, Hui; Fan, Yingying; Hu, Shibin; Liu, Shuhui

2016-08-26

Acetonitrile stacking is an online concentration method that is distinctive due to its inclusion of a high proportion of organic solvent in sample matrices. We previously designed a universal methodology for the combination of liquid-phase microextraction (LPME) and capillary electrophoresis (CE) using acetonitrile stacking and micellar electrokinetic chromatography (MEKC) mode, thereby achieving large-volume injection of the diluted LPME extractant and the online concentration. In this report, the methodology was extended to the analysis of highly substituted hydrophobic chlorophenols in wines using diethyl carbonate as the extractant. Additionally, the mechanism of acetonitrile stacking was studied. The results indicated that the combination of LPME and MEKC exhibited good analytical performance: with ∼40-fold concentration by LPME, a 20-cm (33% of the total length) sample plug injection of an eight-fold dilution of diethyl carbonate with the organic solvent-saline solution produced enrichments higher by a factor of 260-791. Limits of qualification ranged from 5.5 to 16.0ng/mL. Acceptable reproducibilities of lower than 1.8% for migration time and 8.6% for peak areas were obtained. A dual stacking mechanism of acetonitrile stacking was revealed, involving transient isotachophoresis plus pH-junction stacking. The latter was associated with a pH shift induced by the presence of acetonitrile. The pseudo-stationary phase (Brij-35) played an important role in reducing the CE running time by weakening the isotachophoretic migration of the analyte ions following Cl(-) ions. The combination of acetonitrile stacking and nonionic micelle-based MEKC appears to be a perfect match for introducing water-immiscible LPME extractants into an aqueous CE system and can thus significantly expand the application of LPME-CE in green analytical chemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

Methodology of analysis of very weak acids by isotachophoresis with electrospray-ionization mass-spectrometric detection: Anionic electrolyte systems for the medium-alkaline pH range.

Science.gov (United States)

Malá, Zdena; Gebauer, Petr

2018-01-15

This work describes for the first time a functional electrolyte system setup for anionic isotachophoresis (ITP) with electrospray-ionization mass-spectrometric (ESI-MS) detection in the neutral to medium-alkaline pH range. So far no application was published on the analysis of very weak acids by anionic ITP-MS although there is a broad spectrum of potential analytes with pK a values in the range 5-10, where application of this technique promises interesting gains in both sensitivity and specificity. The problem so far was the lack of anionic ESI-compatible ITP systems in the mentioned pH range as all typical volatile anionic system components are fully ionized at neutral and alkaline pH and thus too fast to suit as terminators. We propose an original solution of the problem based on the combination of two ITP methods: (i) use of the hydroxyl ion as a natural and ESI-compatible terminator, and (ii) use of configurations based on moving-boundary ITP. The former method ensures effective stacking of analytes by an alkaline terminator of sufficiently low mobility and the latter offers increased flexibility for tuning of the separation window and selectivity according to actual needs. A theoretical description of the proposed model is presented and applied to the design of very simple functional electrolyte configurations. The properties of example systems are demonstrated by both computer simulation and experiments with a group of model analytes. Potential effects of carbon dioxide present in the solutions are demonstrated for particular systems. Experimental results confirm that the proposed methodology is well capable of performing sensitive and selective ITP-MS analyses of very weak acidic analytes (e.g. sulfonamides or chlorophenols). Copyright © 2017 Elsevier B.V. All rights reserved.

Visible Light Responsive Catalysts Using Quantum Dot-Modified Ti02 for Air and Water Purification

Science.gov (United States)

Coutts, Janelle L.; Levine, Lanfang H.; Richards, Jeffrey T.; Hintze, paul; Clausen, Christian

2012-01-01

The method of photocatalysis utilizing titanium dioxide, TiO2, as the catalyst has been widely studied for trace contaminant control for both air and water applications because of its low energy consumption and use of a regenerable catalyst. Titanium dioxide requires ultraviolet light for activation due to its band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors and are a setback for the technology for space application due to the possibility of Hg contamination. The development of a visible light responsive (VLR) TiO2-based catalyst could lead to the use of solar energy in the visible region (approx.45% of the solar spectrum lies in the visible region; > 400 nm) or highly efficient LEDs (with wavelengths > 400 nm) to make PCO approaches more efficient, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts; those that are available still have poor activity in the visible region compared to that in the UV region. Thus, this study was aimed at the further development of VLR catalysts by a new method - coupling of quantum dots (QD) of a narrow band gap semiconductor (e.g., CdS, CdSe, PbS, ZnSe, etc.) to the TiO2 by two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications, using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems serve as model contaminants for this research. Synthesized catalysts were compared in terms of preparation method, type of quantum dots, and dosage of quantum dots.

Heavy metals, salts and organic residues in old solid urban waste landfills and surface waters in their discharge areas: determinants for restoring their impact.

Science.gov (United States)

Pastor, J; Hernández, A J

2012-03-01

This study was designed to determine the state of polluted soils in the main landfills of the Community of Madrid (central Spain), as part of a continuous assessment of the impacts of urban solid waste (USW) landfills that were capped with a layer of soil 20 years ago. Our analysis of this problem has been highly conditioned by the constant re-use of many of the USW landfills, since they have never been the target of any specific restoration plan. Our periodical analysis of cover soils and soils from discharge areas of the landfills indicates soil pollution has worsened over the years. Here, we examined heavy metal, salts, and organic compounds in soil and surface water samples taken from 15 landfills in the Madrid region. Impacts of the landfill soil covers on nematode and plant diversity were also evaluated. These analyses continue to reveal the presence of heavy metals (Zn, Cu, Cr, Ni, Pb, Cd) in soils, and salts (sulphates, chlorides and nitrates) in soils and surface waters. In addition, non-agricultural organic compounds, mainly aromatic and aliphatic hydrocarbons, often appeared in very high concentrations, and high levels of insecticides such as gamma-HCH (lindane) were also detected in soils. Around 50% of the water samples collected showed chemical demand of oxygen (CDO) values in excess of 150 mg/l. Traces of phenolic compounds were detected in some landfills, some of which exhibited high levels of 2-chlorophenol and pentachlorophenol. All these factors are conditioning both the revegetation of the landfill systems and the remediation of their slopes and terrestrial ecosystems arising in their discharge areas. This work updates the current situation and discusses risks for the health of the ecosystems, humans, domestic animals and wildlife living close to these landfills. Copyright © 2011 Elsevier Ltd. All rights reserved.

Diffused sunlight driven highly synergistic pathway for complete mineralization of organic contaminants using reduced graphene oxide supported photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Babu, Sundaram Ganesh; Ramalingam Vinoth [SRM Research Institute, SRM University, Kattankulathur 603203, Chennai, Tamilnadu (India); Neppolian, Bernaurdshaw, E-mail: neppolian.b@res.srmuniv.ac.in [SRM Research Institute, SRM University, Kattankulathur 603203, Chennai, Tamilnadu (India); Dionysiou, Dionysios D. [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Ashokkumar, Muthupandian [The School of Chemistry, University of Melbourne, Parkville, Melbourne, Victoria 3010 (Australia)

2015-06-30

Highlights: • Diffused sunlight is firstly used as an effective source for the degradation of organics. • More than 10 fold synergistic effect is achieved by sono-photocatalysis. • rGO enhances the degradation efficiency up to 54% as compared with CuO–TiO{sub 2} alone. • Plausible mechanism and intermediates formed are supported with experimental studies. - Abstract: Diffused sunlight is found to be an effective light source for the efficient degradation and mineralization of organic pollutant (methyl orange as a probe) by sono-photocatalytic degradation using reduced graphene oxide (rGO) supported CuO–TiO{sub 2} photocatalyst. The prepared catalysts are characterized by XRD, XPS, UV–vis DRS, PL, photoelectrochemical, SEM-EDS and TEM. A 10 fold synergy is achieved for the first time by combining sonochemical and photocatalytic degradation under diffused sunlight. rGO loading augments the activity of bare CuO–TiO{sub 2} more than two fold. The ability of rGO in storing, transferring, and shuttling electrons at the heterojunction between TiO{sub 2} and CuO facilitates the separation of photogenerated electron–hole pairs, as evidenced by the photoluminescence results. The complete mineralization of MO and the by-products within a short span of time is confirmed by TOC analysis. Further, hydroxyl radical mediated degradation under diffused sunlight is confirmed by LC–MS. This system shows similar activity for the degradation of methylene blue and 4-chlorophenol indicating the versatility of the catalyst for the degradation of various pollutants. This investigation is likely to open new possibilities for the development of highly efficient diffused sunlight driven TiO{sub 2} based photocatalysts for the complete mineralization of organic contaminants.

Nanostructured CoP: An efficient catalyst for degradation of organic pollutants by activating peroxymonosulfate

Energy Technology Data Exchange (ETDEWEB)

Luo, Rui; Liu, Chao; Li, Jiansheng, E-mail: lijsh@mail.njust.edu.cn; Wang, Jing; Hu, Xingru; Sun, Xiuyun; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

2017-05-05

Highlights: • The CoP/PMS system was first presented for decomposition of pollutants. • CoP exhibited dramatic catalytic activity. • Broadened pH range and favorable anti-interference of anions were achieved. • A possible mechanism for activation of PMS by CoP was proposed. - Abstract: A new catalyst system of CoP/peroxymonosulfate (PMS) is presented, which achieved significant improvement in catalytic activity. Nanostructured CoP, obtained by a simple solid-state reaction, exhibited dramatic catalytic activity with 97.2% degradation of orange II of 100 ppm within 4 min. Moreover, the high efficiency could be reached for other phenolic pollutants, i.e., phenol and 4-chlorophenol. The reaction rate is much higher than the most reported catalysts. Effect of parameters on catalytic activity of the catalyst was studied in detail. Notably, initial pH of the solution had a slight negative effect on the catalytic performance over the pH range 4.07–10.92, suggesting that CoP has the great adaptability of pH. CoP/PMS demonstrated excellent anti-interference performance toward anions (Cl{sup −}, NO{sub 3}{sup −}, and HCO{sub 3}{sup −}). In addition, the pathway of degradation of orange II is proposed by analyzing its intermediates. Based on the XPS spectra of CoP, the identification of the reactive species (·OH and SO{sub 4}·{sup −}) by electron paramagnetic resonance (EPR) analysis and quenching tests, a possible mechanism for activation of PMS by CoP was proposed. Considering the dramatic catalytic activity, a wide range of pH catalyst suited, CoP is believed to provide robust support for the promising industrial application of AOPs.

Enhancing the reactivity of bimetallic Bi/Fe{sup 0} by citric acid for remediation of polluted water

Energy Technology Data Exchange (ETDEWEB)

Gong, Jianyu; Lee, Chung-Seop; Kim, Eun-Ju [School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Chang, Yoon-Young [Department of Environmental Engineering, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Chang, Yoon-Seok, E-mail: yschang@postech.ac.kr [School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

2016-06-05

Highlights: • A novel bismuth modified zero valent iron (Bi/Fe{sup 0}) was synthesized. • The Bi/Fe{sup 0} + CA(citric acid) + O{sub 2} system could produce ·OH and ·O{sub 2}{sup −}. • Some recalcitrant pollutants could be treated by Bi/Fe{sup 0} + CA + O{sub 2} in a short time. • The formation of Fe(III)-citric results in the generation of ·OH and ·O{sub 2}{sup −}. - Abstract: In this study, the environmentally benign citric acid (CA) was utilized to improve the aerobic degradation of 4-chlorophenol (4-CP) over bismuth modified nanoscale zero-valent iron (Bi/Fe{sup 0}). The characterization results revealed the existence of bismuth covering on the Fe{sup 0} surface under zero-valent state. And, the Bi/Fe{sup 0}-CA + O{sub 2} system performed excellent reactivity in degradation of 4-CP due to the generation of reactive oxygen species (ROS), which was confirmed by electron spin resonance (ESR) spectroscopy. After 30 min of reaction, 80% of 4-CP was removed using Bi/Fe{sup 0}-CA + O{sub 2} accompanying with high dechlorination rate. The oxidative degradation intermediates were analyzed by HPLC and LC-MS. We found that CA could promote the bismuth-iron system to produce much reactive oxygen species ROS under both aerobic and anaerobic conditions due to its ligand function, which could react with Fe{sup 3+} to form a ligand complex (Fe(III)Cit), accompanying with a considerable production of Fe{sup 2+} and H{sub 2}O{sub 2}. This study provides a new strategy for generating ROS on nZVI and suggests its application for the mineralization of many recalcitrant pollutants.

Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

International Nuclear Information System (INIS)

Gao, Juanjuan; Liu, Maoxiang; Song, Haiou; Zhang, Shupeng; Qian, Yueyue; Li, Aimin

2016-01-01

Highlights: • Phenol detection based on coupled cMWCNT/CD edge-functionalized graphene composite. • Increased conductivity can inspire enhancement of electrocatalytic performance. • The synergistic combination of the trace amounts of CDs and cMWCNT is a pivotal. • GN-CD-cMWCNT shows an excellent electrocatalytic and anti-interference ability. - Abstract: Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027 μM (S/N = 3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

Tentacle carrier for immobilization of potato phenoloxidase and its application for halogenophenols removal from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Loncar, Nikola, E-mail: nloncar@chem.bg.ac.rs [Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade (Serbia); Vujcic, Zoran, E-mail: zvujcic@chem.bg.ac.rs [Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade (Serbia)

2011-11-30

Highlights: Black-Right-Pointing-Pointer We synthesized novel immobilization carrier from reused DEAE-cellulose. Black-Right-Pointing-Pointer We used it for immobilization of PPO through coordinative bonding with copper ions. Black-Right-Pointing-Pointer Immobilized PPO showed better characteristics than soluble PPO. Black-Right-Pointing-Pointer TC-PPO removed over 90% of halogenophenols at concentration of 100 mg/L. - Abstract: Halogenated compounds represent one of the most dangerous environmental pollutants, due to their widespread usage as biocides, fungicides, disinfectants, solvent and other industrial chemicals. Immobilization of a protein through coordinate bonds formed with divalent metal ions is becoming an attractive method due to its reversible nature, since the protein may be easily removed from the support matrix through interruption of the protein-metal bond hence giving inherently cleaner and cheaper technology for wastewater treatment. We have synthesized novel 'tentacle' carrier (TC) and used it for immobilization of partially purified potato polyphenol oxidase (PPO). The obtained biocatalyst TC-PPO showed pH optimum at 7.0-8.0 and temperature optimum at 25 Degree-Sign C. Immobilized PPO shows almost 100% of activity at 0 Degree-Sign C. TC-PPO was more resistant to the denaturation induced by sodium dodecyl sulphate (SDS) detergent as compared to its soluble counterpart and was even slightly activated at SDS concentration of 1%. TC-PPO was tested in the batch reactor for 4-chlorophenol and 4-bromophenol removal. More than 90% removal was achieved for both halogenophenols at concentration of 100 mg/L from aqueous solution. For both halogenophenols TC-PPO works with over 90% removal during first three cycles which decrease to 60% removal efficiency after six cycles each of 8 h duration.

Sampling and analysis of the inactive waste tanks TH-2, WC-1, and WC-15

International Nuclear Information System (INIS)

Autrey, J.W.; Keller, J.M.; Griest, W.H.; Botts, J.L.; Schenley, R.L.; Sipe, M.A.

1992-02-01

Thirty-eight inactive liquid low-level radioactive waste tanks are currently managed by the Environmental Restoration Program of Oak Ridge National Laboratory. The contents of these tanks are to be characterized in preparation for future corrective actions and remediation activities as part of compliance with the pending Federal Facility Agreement for the Oak Ridge Reservation. Twenty-nine of these tanks were sampled and analyzed in 1989. Three of the tanks (TH-2, WC-1, and WC-15) were not accessible from the surface and thus were not sampled until 1990. This report presents the sampling and analytical results of that campaign. All three tanks in this report had negligible regulatory organic compounds in the samples that were collected. There were no US Environmental Protection Agency (EPA) Target Compound List (TCL) constituents for volatile organics detected in any of the aqueous samples. The only semivolatile organics detected were 2-chlorophenol (52 μg/L) in tank TH-2 and dichloroethane (14--15 μg/L) and diethyl either (15--17 μg/L) in tank WC-15. A thin oil layer was discovered floating on top of the aqueous contents in tank WC-15. The analysis of the oil layer detected no volatile organics and showed only one EPA TCL constituent, di-n-butylphthalate, at 1900 μg/L. Low levels of Resource Conservation and Recovery Act (RCRA) metals were observed in the samples from tank TH-2, but only the mercury level exceeded the RCRA limit. Samples from tank WC-1 had elevated levels of the RCRA metals barium, chromium, and lead. There were also finely suspended particles in one of the samples from tank WC-1, which was filtered and analyzed separately. This solid fines have levels of transuranium elements 238 Pu and 241 Am high enough to classified as transuranic waste

Anaerobic biological treatment

International Nuclear Information System (INIS)

Speece, R.E.

1990-01-01

The Enso-Fenox process has been very successfully used to remove chlorinated phenolic compounds from pulp bleaching effluents. It is a two-stage anaerobic/aerobic process consisting of a nonmethanogenic anaerobic fluidized bed followed by a trickling filter. Studies have been conducted on reductive dechlorination of chlorinated aromatic compounds under anaerobic conditions with chlorinated phenols as the sole carbon and energy source. Approximately 40% of the added chlorophenols was converted to CH 4 and CO 2 . Substrate loading rates were 20 mg/L/d at hydraulic detention times of 2-4 days with 90% substrate conversion efficiency. Reductive dechlorination of mono, di-, tri-, and pentachlorophenols has been demonstrated in anaerobic sewage sludge. The following constituents were tested in the laboratory at their approximate concentrations in coal conversion wastewater (CCWW) and were anaerobically degraded in serum bottles: 1,000 mg/L phenol; 500 mg/L resorcinol; 1,000 mg/L benzoic acid; 500 mg/L p-cresol; 200 mg/L pyridine; 2,000 mg/L benzoic acid; 250 mg/L 40 methylcatechol; 500 mg/L 4-ethylpyridine; and 2,000 mg/L hexanoic acid. A petrochemical may initially exhibit toxicity to an unacclimated population of methane-fermenting bacteria, but with acclimation the toxicity may be greatly reduced or disappear. In addition, the microorganisms may develop the capacity to actually degrade compounds which showed initial toxicity. Since biomass digestion requires a complete consortium of bacteria, it is relevant to study the effect of a given process as well as to individual steps within the process. A toxicant can inhibit the rate-limiting step and/or change the step that is rate-limiting. Both manifestations of toxicity can severely affect the overall process

Interactions between urinary 4-tert-octylphenol levels and metabolism enzyme gene variants on idiopathic male infertility.

Directory of Open Access Journals (Sweden)

Yufeng Qin

Full Text Available Octylphenol (OP and Trichlorophenol (TCP act as endocrine disruptors and have effects on male reproductive function. We studied the interactions between 4-tert-Octylphenol (4-t-OP, 4-n- Octylphenol (4-n-OP, 2,3,4-Trichlorophenol (2,3,4-TCP, 2,4,5-Trichlorophenol (2,4,5-TCP urinary exposure levels and polymorphisms in selected xenobiotic metabolism enzyme genes among 589 idiopathic male infertile patients and 396 controls in a Han-Chinese population. Ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS was used to measure alkylphenols and chlorophenols in urine. Polymorphisms were genotyped using the SNPstream platform and the Taqman method. Among four phenols that were detected, we found that only exposure to 4-t-OP increased the risk of male infertility (P(trend = 1.70×10(-7. The strongest interaction was between 4-t-OP and rs4918758 in CYP2C9 (P(inter = 6.05×10(-7. It presented a significant monotonic increase in risk estimates for male infertility with increasing 4-t-OP exposure levels among men with TC/CC genotype (low level compared with non-exposed, odds ratio (OR = 2.26, 95% confidence intervals (CI = 1.06, 4.83; high level compared with non-exposed, OR = 9.22, 95% CI = 2.78, 30.59, but no associations observed among men with TT genotype. We also found interactions between 4-t-OP and rs4986894 in CYP2C19, and between rs1048943 in CYP1A1, on male infertile risk (P(inter = 8.09×10(-7, P(inter = 3.73×10(-4, respectively.We observed notable interactions between 4-t-OP exposure and metabolism enzyme gene polymorphisms on idiopathic infertility in Han-Chinese men.

Contaminant risks from biosolids land application Contemporary organic contaminant levels in digested sewage sludge from five treatment plants in Greater Vancouver, British Columbia

International Nuclear Information System (INIS)

Bright, D.A.; Healey, N.

2003-01-01

The risks of organic contaminants in sewage sludges are evaluated. - This study examines the potential for environmental risks due to organic contaminants at sewage sludge application sites, and documents metals and various potential organic contaminants (volatile organics, chlorinated pesticides, PCBs, dioxins/furans, extractable petroleum hydrocarbons, PAHs, phenols, and others) in current production biosolids from five wastewater treatment plants (WWTPs) within the Greater Vancouver Regional District (GVRD). There has been greater focus in Europe, North America and elsewhere on metals accumulation in biosolids-amended soil than on organic substances, with the exception of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. Another objective, therefore, was to evaluate the extent to which management of biosolids re-use based on metal/metalloid levels coincidentally minimizes environmental risks from organic contaminants. Historical-use contaminants such as chlorophenols, PCBs, and chlorinated pesticides were not detected at environmentally relevant concentrations in any of the 36 fresh biosolids samples, and appear to have virtually eliminated from sanitary collection system inputs. The few organic contaminants found in freshly produced biosolids samples that exhibited high concentrations relative to British Columbia and Canadian soil quality benchmarks included p-cresol, phenol, phenanthrene, pyrene, naphthalene, and heavy extractable petroleum hydrocarbons (HEPHs-nCl9-C34 effective carbon chain length). It was concluded that, with the exception of these petroleum hydrocarbon constituents or their microbial metabolites, the mixing of biosolids with uncontaminated soils during land application and based on the known metal concentrations in biosolids from the Greater Vancouver WWTPs investigated provides adequate protection against the environmental risks associated with organic substances such as dioxins and furans, phthalate esters, or volatile

Synthesis of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction with enhanced visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Li, Shijie [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Xu, Kaibing [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Research Center for Analysis and Measurement, Donghua University, Shanghai 201620 (China); Hu, Shiwei, E-mail: hushiweihai@163.com [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Jiang, Wei [Innovation & Application Institute, Zhejiang Ocean University, Zhoushan, Zhejiang Province 316022 (China); Zhejiang Provincial Key Laboratory of Health Risk Factors for Seafood, Zhoushan Municipal Center for Disease Control and Prevention, Zhoushan 316021 (China); Zhang, Junlei [Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200433 (China); Liu, Jianshe [State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Zhang, Lisha, E-mail: lszhang@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)

2017-03-01

Highlights: • Ag{sub 2}O/BiOCOOH p-n heterojunctions are prepared by a solvothermal deposition-precipitation method. • They consist of flower-like BiOCOOH microspheres decorated with Ag{sub 2}O nanoparticles. • Heterojunction with the Ag/Bi molar ratio of 0.2/1 showed the highest photocatalytic activity. • The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species. - Abstract: The development of efficient semiconductor heterojunction photocatalysts has drawn much attention. Herein, we have reported a kind of flower-like Ag{sub 2}O/BiOCOOH p-n heterojunction as a novel and efficient visible-light-driven photocatalyst. The Ag{sub 2}O/BiOCOOH heterojunctions have been successfully prepared via a solvothermal precipitation-deposition method. They consist of flower-like BiOCOOH microspheres (diameters: 1–2.5 μm) decorated with Ag{sub 2}O nanoparticles (size: ∼14 nm). In addition, optical characterization reveals that they have broad visible-light photo-absorption. Importantly, under visible-light irradiation (λ > 400 nm), all Ag{sub 2}O/BiOCOOH heterojunctions exhibit enhanced photocatalytic activity than pure BiOCOOH or Ag{sub 2}O for the degradation of rhodamine B (RhB) dye and para-chlorophenol (4-CP). Especially, the Ag{sub 2}O/BiOCOOH heterojunction with the Ag/Bi molar ratio of 0.2/1 shows the highest photocatalytic activity, which is even higher than the activity from the mechanical mixture (8 wt% Ag{sub 2}O + 92 wt% BiOCOOH). This enhanced photocatalytic performance could be predominantly attributed to the efficient separation of photogenerated electron-hole pairs. The photogenerated holes (h{sup +}) and superoxide radical anions (·O{sub 2}{sup −}) have been found to be the main reactive species responsible for the photodegradation of RhB dye in aqueous solution. Therefore, the Ag{sub 2}O/BiOCOOH p-n heterojunction has great potential to be used as a kind of efficient

Visible-Light-Responsive Catalysts Using Quantum Dot-Modified TiO2 for Air and Water Purification

Science.gov (United States)

Coutts, Janelle L.; Hintze, Paul E.; Clausen, Christian; Richards, Jeffrey Todd

2014-01-01

Photocatalysis, the oxidation or reduction of contaminants by light-activated catalysts, utilizing titanium dioxide (TiO2) as the catalytic substrate has been widely studied for trace contaminant control in both air and water applications. The interest in this process is due primarily to its low energy consumption and capacity for catalyst regeneration. Titanium dioxide requires ultraviolet light for activation due to its relatively large band gap energy of 3.2 eV. Traditionally, Hg-vapor fluorescent light sources are used in PCO reactors; however, the use of mercury precludes the use of this PCO technology in a spaceflight environment due to concerns over crew Hg exposure. The development of a visible-light responsive (VLR) TiO2-based catalyst would eliminate the concerns over mercury contamination. Further, VLR development would allow for the use of ambient visible solar radiation or highly efficient LEDs, both of which would make PCO approaches more efficient, flexible, economical, and safe. Though VLR catalyst development has been an active area of research for the past two decades, there are few commercially available VLR catalysts. Those VLR catalysts that are commercially available do not have adequate catalytic activity, in the visible region, to make them competitive with those operating under UV irradiation. This study was initiated to develop more effective VLR catalysts through a novel method in which quantum dots (QD) consisting of narrow band gap semiconductors (e.g., CdS, CdSe, PbS, ZnSe, etc.) are coupled to TiO2 via two preparation methods: 1) photodeposition and 2) mechanical alloying using a high-speed ball mill. A library of catalysts was developed and screened for gas and aqueous phase applications using ethanol and 4-chlorophenol as the target contaminants, respectively. Both target compounds are well studied in photocatalytic systems and served as model contaminants for this research. Synthesized catalysts were compared in terms of

Accelerated redox reaction between chromate and phenolic pollutants during freezing

Energy Technology Data Exchange (ETDEWEB)

Ju, Jinjung; Kim, Jaesung [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of); Vetráková, Ľubica [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Seo, Jiwon [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Heger, Dominik [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lee, Changha [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Yoon, Ho-Il [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Kitae, E-mail: ktkim@kopri.re.kr [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Jungwon, E-mail: jwk@hallym.ac.kr [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of)

2017-05-05

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

An overview of human biomonitoring of environmental chemicals in the Canadian Health Measures Survey: 2007-2019.

Science.gov (United States)

Haines, Douglas A; Saravanabhavan, Gurusankar; Werry, Kate; Khoury, Cheryl

2017-03-01

Human biomonitoring (HBM) is used to indicate and quantify exposure by measuring environmental chemicals, their metabolites or reaction products in biological specimens. The biomonitoring component of the Canadian Health Measures Survey (CHMS) is the most comprehensive initiative providing general population HBM data in Canada. The CHMS is an ongoing cross-sectional direct measures survey implemented in 2-year cycles. It provides nationally-representative data on health, nutritional status, environmental exposures, and related risks and protective characteristics. The survey follows a robust planning, design and sampling protocol as well as a comprehensive quality assurance and quality control regime implemented for all aspect of the survey to ensure the validity of the HBM results. HBM blood and urine data are available for CHMS cycles 1 (2007-2009), 2 (2009-2011) and 3 (2012-2013). Field collection has been completed for cycle 4 (2014-2015), with cycle 5 (2016-2017) in progress and cycle 6 planning (2018-2019) being finalized. Biomonitoring results for 279 chemicals are expected over the six cycles of the CHMS (220 in individual blood, urine or hair samples, and 59 in pooled serum samples). The chemicals include metals and trace elements, polychlorinated biphenyls (PCBs), organochlorines, flame retardants, perfluoroalkyl substances, volatile organic compounds (VOCs) and metabolites, environmental phenols, triclocarban, acrylamide, pesticides (e.g., triazines, carbamates, organophosphates, phenoxy, pyrethroids) and/or their metabolites, chlorophenols, polycyclic aromatic hydrocarbon (PAH) metabolites, phthalates and alternate plasticizer metabolites, and tobacco biomarkers. Approximately one half of the chemicals measured in individual blood and urine samples over the first three cycles were detected in more than 60% of samples. CHMS biomonitoring data have been used to establish baseline HBM concentrations in Canadians; inform public health, regulatory risk

For successfully completed clean-ups treating different kinds of contaminants

Energy Technology Data Exchange (ETDEWEB)

Bachmann, A.; Bentz, R.; Huerzeler, R.A.; Matter, B. [Ciba Specialty Chemicals Inc., Basel (Switzerland)

2003-07-01

In this Special Session 4 remediation projects are presented, that were run in different environments and under different constraints. The projects / sites showed the following characteristics: Amponville (F) This project represents a successful clean up of an uncontrolled dump by drums containing Chlorophenol-wastes from an old agrochemical production site. Contaminated sandy soil had to be excavated and treated in a Thermal Desorption unit on site. An interactive CD-ROM data medium was created for documentation. Niederglatt (CH) A old industrial area contaminated by organics (hydrocarbons, polyaromatics) as well as by chromium Cr(VI) was remediated by soil-excavation. The soil had to be analysed, separated and treated accordingly. Chromium-contaminated material had to be treated physically and chemically. The soil affected by organic pollutants had to be washed off-site. Special attention was given to the water flowing off the site, groundwater control and to dust deposit measures in the near environment. Dielsdorf (CH) This site contained wastes from former Lindane-production, containing HCH, Dinitro-o-Cresol and metals like As, Cu and Pb. The contaminated soil and the wastes had to be excavated, analysed, partly backfilled and the rest treated in different ways. Residual pollutants concentration was calculated following a risk-analysis/mobility-calculation and agreed upon with the authorities before starting the remediation work. Schweizerhalle (CH) A huge fire left an area of contaminated soil that was affected by argo-chemicals and their incineration-products. The most harmful pollutants were mercury and phosphoric esters. After coverage by a tent and lowering of the groundwater level the gravel and the sandy soil was excavated and treated in an on-site large-scale Soil Washing and Treating installation by using surfactants and other reagents to separate the pollutants. Most of the soil could be backfilled on-site. Less than 5% of the soil volume containing

Evaluation of sunlight induced structural changes and their effect on the photocatalytic activity of V{sub 2}O{sub 5} for the degradation of phenols

Energy Technology Data Exchange (ETDEWEB)

Aslam, M. [Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Ismail, Iqbal M.I. [Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Salah, Numan [Centre of Nanotechnology, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Chandrasekaran, S. [Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Qamar, M.Tariq [Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Hameed, A., E-mail: afmuhammad@kau.edu.sa [Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah 21589 (Saudi Arabia); National Centre for Physics, Quaid-e-Azam University, Islamabad 44000 (Pakistan)

2015-04-09

Highlights: • The interaction of UV photons of sunlight induces defects in V{sub 2}O{sub 5}. • The photon induced defects promotes the trapping and transfer of excited electrons. • The nature of the substituent at 2-position affects the degradation process. • The formation of the intermediates is influenced by the nature of substituents. • The released ions are subjected further transformation. - Abstract: Despite knowing the fact that vanadium pentoxide is slightly soluble in aqueous medium, its photocatalytic activity was evaluated for the degradation of phenol and its derivatives (2-hydroxyphenol, 2-chlorophenol, 2-aminophenol and 2-nitrophenol) in natural sunlight exposure. The prime objective of the study was to differentiate between the homogeneous and heterogeneous photocatalysis incurred by dissolved and undissolved V{sub 2}O{sub 5} in natural sunlight exposure. V{sub 2}O{sub 5} was synthesized by chemical precipitation procedure using Triton X-100 as morphology mediator and characterized by DRS, PLS, Raman, FESEM and XRD. A lower solubility of ∼5% per 100 ml of water at 23 °C was observed after calcination at 600 °C. The study revealed no contribution of the dissolved V{sub 2}O{sub 5} in the photocatalytic process. In sunlight exposure, V{sub 2}O{sub 5} powder exhibited substantial activity for the degradation, however, a low mineralization of phenolic substrates was observed. The initial low activity of V{sub 2}O{sub 5} followed by a sharp increase both in degradation and mineralization in complete spectrum sunlight exposure, was further investigated that revealed the decrease in the bandgap and the reduction in the particle size with the interaction of UV photons (<420 nm) as this effect was not observable in the exposure of visible region of sunlight. The role of the chemically different substituents attached to an aromatic ring at 2-positions and the secondary interaction of released ions during the degradation process with the reactive

Accelerated redox reaction between chromate and phenolic pollutants during freezing

International Nuclear Information System (INIS)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-01-01

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

Sorption performance and mechanism of a sludge-derived char as porous carbon-based hybrid adsorbent for benzene derivatives in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Kong, Lingjun [School of Environmental Science and Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Xiong, Ya, E-mail: cesxya@mail.sysu.edu.cn [School of Environmental Science and Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275 (China); Sun, Lianpeng; Tian, Shuanghong [School of Environmental Science and Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275 (China); Xu, Xianyan; Zhao, Cunyuan [School of Chemistry and Chemical Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Luo, Rongshu [School of Environmental Science and Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Yang, Xin [School of Environmental Science and Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, 510275 (China); Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou, 510275 (China); Shih, Kaimin [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR (China); Liu, Haiyang [Department of Chemistry, South China University of Technology, Guangzhou, 510641 (China)

2014-06-01

Highlights: • Hierarchical porous sludge char were fabricated by pyrolysis at 500 °C. • A stronger Si–O bond (1.83 Å and 1.87 Å) between the carboxyl and SiO{sub 2} was found. • Quantum chemistry calculation confirmed the interaction of Si–O and H–O bonds. • Multiple model (Q{sub T} = Q{sub A} + K{sub P}Ce) was presented in the sludge char sorption process. - Abstract: A porous sludge-derived char was prepared by a new one-step pyrolytic process with citric acid–ZnCl{sub 2} mixed fabricating-pore agents. The sludge-derived char was confirmed to be a hierarchically porous hybrid adsorbent containing-elemental carbon, -highly carbonized organic species and -inorganic ash with a great surface area of 792.4 m{sup 2} g{sup −1}. It was used as a carbon-based hybrid adsorbent for four benzene derivatives including 4-chlorophenol, phenol, benzoic acid and 4-hydroxylbenzoic acid in aqueous solution. Results showed that their sorption isotherms were nonlinear at low concentrations and linear at high concentrations. The sorption performance could be described by a multiple sorption model (Q{sub T} = Q{sub A} + K{sub P}C{sub e}). The order of these partition sorption coefficients (K{sub P}) of these benzene derivatives was consistent with their octanol–water partition coefficients (log K{sub ow}), but those saturated amounts (Q{sub A}) were inconsistent with their log K{sub ow}. The inconstancy was found to be considerably dependent on the preferential interaction of benzoic acid with SiO{sub 2} in the sludge-derived char. Quantum theoretical calculation confirmed that the preferential interaction was attributed to the formation of hydrogen bonds (1.61 and 1.69 Å) and new Si–O bonds (1.83 and 1.87 Å) between the carboxyl of benzoic acid and the SiO{sub 2} surface in the sorption process.

Post-treatment of biologically treated wastewater containing organic contaminants using a sequence of H2O2 based advanced oxidation processes: photolysis and catalytic wet oxidation.

Science.gov (United States)

Rueda-Márquez, J J; Sillanpää, M; Pocostales, P; Acevedo, A; Manzano, M A

2015-03-15

In this paper the feasibility of a multi-barrier treatment (MBT) for the regeneration of synthetic industrial wastewater (SIWW) was evaluated. Industrial pollutants (orange II, phenol, 4-chlorophenol and phenanthrene) were added to the effluent of municipal wastewater treatment plant. The proposed MBT begins with a microfiltration membrane pretreatment (MF), followed by hydrogen peroxide photolysis (H2O2/UVC) and finishing, as a polishing step, with catalytic wet peroxide oxidation (CWPO) using granular activated carbon (GAC) at ambient conditions. During the microfiltration step (0.7 μm) the decrease of suspended solids concentration, turbidity and Escherichia coli in treated water were 88, 94 and 99%, respectively. Also, the effluent's transmittance (254 nm) was increased by 14.7%. Removal of more than 99.9% of all added pollutants, mineralization of 63% of organic compounds and complete disinfection of total coliforms were reached during the H2O2/UVC treatment step (H2O2:TOC w/w ratio = 5 and an UVC average dose accumulated by wastewater 8.80 WUVC s cm(-2)). The power and efficiency of the lamp, the water transmittance and photoreactor geometry are taken into account and a new equation to estimate the accumulated dose in water is suggested. Remaining organic pollutants with a higher oxidation state of carbon atoms (+0.47) and toxic concentration of residual H2O2 were present in the effluent of the H2O2/UVC process. After 2.3 min of contact time with GAC at CWPO step, 90 and 100% of total organic carbon and residual H2O2 were removed, respectively. Also, the wastewater toxicity was studied using Vibrio fischeri and Sparus aurata larvae. The MBT operational and maintenance costs (O&M) was estimated to be 0.59 € m(-3). Copyright © 2015 Elsevier Ltd. All rights reserved.

Amino modified multi-walled carbon nanotubes/polydimethylsiloxane coated stir bar sorptive extraction coupled to high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental samples.

Science.gov (United States)

Hu, Cong; Chen, Beibei; He, Man; Hu, Bin

2013-07-26

In this work, amino modified multi-walled carbon nanotubes/polydimethylsiloxane (multi-walled carbon nanotubes-4,4'-diaminodiphenylmethane/polydimethylsiloxane, MWCNTs-DDM/PDMS) was synthesized, and utilized as a novel coating for stir bar sorptive extraction (SBSE) of seven phenols (phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-choro-m-cresol and 2,4,6-trichlorphenol) in environmental water and soil samples, followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The prepared MWCNTs-DDM/PDMS coated stir bar was characterized and good preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.7% to 11.3% (n=9) in one batch, and from 4.8% to 13.9% (n=8) among different batches. Several parameters affecting the extraction of seven target phenols by MWCNTs-DDM/PDMS-SBSE including extraction time, stirring rate, pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.14μg/L (2-nitrophenol) to 1.76μg/L (phenol) and the limits of quantification (LOQs, S/N=10) were found to be in the range of 0.46μg/L (2-nitrophenol) to 5.8μg/L (phenol). The linear range was 5-1000μg/L for phenol and 4-nitrophenol, 1-1000μg/L for 2-nitrophenol and 2-1000μg/L for other phenols, respectively. The RSDs of the developed method were in the range of 6.2-11.6% (n=8, c=10μg/L) and the enrichment factors were from 6.5 to 62.8-fold (theoretical enrichment factor was 100-fold). The proposed method was successfully applied to the analysis of phenols in environmental water and soil samples, and good recoveries were obtained for the spiked samples. The proposed method is simple, highly sensitive and suitable for the analysis of trace phenols in environmental samples with complex matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

Organic and metallic pollutants in water treatment and natural wetlands: a review.

Science.gov (United States)

Haarstad, K; Bavor, H J; Mæhlum, T

2012-01-01

A literature review shows that more than 500 compounds occur in wetlands, and also that wetlands are suitable for removing these compounds. There are, however, obvious pitfalls for treatment wetlands, the most important being the maintenance of the hydraulic capacity and the detention time. Treatment wetlands should have an adapted design to target specific compounds. Aquatic plants and soils are suitable for wastewater treatment with a high capacity of removing nutrients and other substances through uptake, sorption and microbiological degradation. The heavy metals Cd, Cu, Fe, Ni and Pb were found to exceed limit values. The studies revealed high values of phenol and SO(4). No samples showed concentrations in sediments exceeding limit values, but fish samples showed concentrations of Hg exceeding the limit for fish sold in the European Union (EU). The main route of metal uptake in aquatic plants was through the roots in emergent and surface floating plants, whereas in submerged plants roots and leaves take part in removing heavy metals and nutrients. Submerged rooted plants have metal uptake potential from water as well as sediments, whereas rootless plants extracted metals rapidly only from water. Caution is needed about the use of SSF CWs (subsurface flow constructed wetlands) for the treatment of metal-contaminated industrial wastewater as metals are shifted to another environmental compartment, and stable redox conditions are required to ensure long-term efficiency. Mercury is one of the most toxic heavy metals and wetlands have been shown to be a source of methylmercury. Methyl Hg concentrations are typically approximately 15% of Hgt (total mercury). In wetlands polycyclic aromatic hydrocarbons (PAH), bisphenol A, BTEX, hydrocarbons including diesel range organics, glycol, dichlorodiphenyltrichloroethane (DDT), polychlorinated biphenyls (PCB), cyanide, benzene, chlorophenols and formaldehyde were found to exceed limit values. In sediments only PAH and PCB

Influence of the particle size of activated mineral carbon on the phenol and chlorophenol adsorption; Influencia del tamano de particula de carbon mineral activado sobre la adsorcion de fenol y clorofenol

Energy Technology Data Exchange (ETDEWEB)

Garcia M, A

2001-07-01

Water pollution by phenolic compounds is a problem that requires a solution since these phenolic compounds are not completely biodegradable, they accumulate through the food chains and they are quite toxic when enter in contact with living organisms. In human beings, ingestion or contact of the skin with this type of compounds produces irritation and damages mainly to the liver and kidneys. In fact, the Environmental Protection Agency of the United States (EPA assigned nine phenolic compounds among the 275 most toxic substances in 1991. Phenols are found in wastewater from agriculture and industry, because phenolic compounds are used as pesticides and in diverse industrial activities. The treatment of this type of water is not simple because they are generally composed of a mixture of residuals with different chemical nature A useful method for the removal of phenols is the adsorption by activated carbon, since this material has a great surface area and it can be regenerated. The adsorption process depends, among other factors, on the activated carbon characteristics. When they are modified, their capacity to remove pollutants from the water changes. The effect of activated carbon particle size on the removal of phenolic compounds has not been completely studied. Therefore, the aim of this work was to determine the influence of the mineral activated carbon particle size on the phenol and 4-chloro phenol adsorption in aqueous solution, on adsorption column system. The results of the present work indicate that the mineral activated carbon particle size has a very important influence on the adsorption of phenol and 4-chloro phenol. When the particles were smaller, the retention quantities of phenol and 4-chloro phenol increased. This behavior was related to the particle characteristics of the mineral activated carbon such as surface area and pore volume, while other factors such as elementary composition of the activated carbon did not influence the adsorption process in an important way. Finally, when the particle size decreased, the saturation percentage decreased as well as the adsorption capacity increased for the studied phenolic compounds. (Author)

Adsorción de Fenol y 3-Cloro Fenol sobre Carbones Activados mediante Calorimetría de Inmersión Adsorption of Phenol and 3-Chlorophenol n Activated Carbons using Immersion Calorimetry

OpenAIRE

Juan C Moreno-Piraján; Luisa F Navarrete; Liliana Giraldo; Vanessa García

2007-01-01

Se ha determinado la entalpía de inmersión de cinco muestras de carbón activado, obtenidas a partir de diferentes materiales lignocelulósicos, con diferente grado de activación en disoluciones acuosas de fenol y 3-cloro fenol con el fin de caracterizar la interacción sólido-disolución acuosa, obteniéndose valores entre 6.80 y 13.9 Jg-1. Se determinó también, las entalpías de inmersión de estos carbones activados en disoluciones de NaOH y HCl 0.1 M, obteniéndose los más altos valores de la ent...

Contribution to immersed arc plasma study: applications to organic aqueous effluent decontamination and gasification; Contribution a l'etude de plasmas d'arc immerge: applications a la decontamination et a la gazeification d'effluents organiques aqueux

Energy Technology Data Exchange (ETDEWEB)

Boudesocque, N

2007-07-15

This work is concerned with decontamination and gasification of aqueous organic liquid waste by immersed thermal plasma technology. In this concept, the organic compounds are decomposed into gas by high temperature plasma. A quench of about 107-108 K/s, is obtained by immersion into a given effluent. Two kinds of arc plasma are studied. The first one is an immersed electrical arc stricken between two graphite electrodes. The second one is a plasma jet generated by a non-transferred plasma torch. For dilute liquid waste (1 g/L) containing molecules incompatible with conventional biological processes, the hydroxyl radicals (OH{sup 0}) are continuously produced by the plasma jet directly into the solution allowing complete molecule mineralization into carbon dioxide and water. The hetero-atoms, if present, are converted into solvated ions. The decomposition of the molecules, such as chloro-phenols and aniline, are studied. Considering the identified intermediate products, a reaction mechanism is proposed. For each tested molecules, their concentration decreased at least of 90 percent. Based on the 'gasosiphon' phenomenon, the experimental reactor insures the simultaneous recirculation of both gas and liquid phases. The hydrodynamic was studied using in situ high frequency imaging technology. A CFD code was applied for numerical simulation of the observed recirculation phenomena. The results were compared with obtained experimental data. In the case of concentrated liquid waste ({>=} 100 g/L), syngas was produced by thermal cracking of organic molecules. The best measured composition of the gas is about 45% v/v of H{sub 2} and 45 % v/v of CO when an electrical arc is used. The usability of both studied plasma types were investigated in this field. The experimental study was carried on using fructose and glucose solution (several hundreds g/L) as surrogated effluent. With a specific injection method, gasification rate is about 30 % with one way. Optical

The use of comprehensive two-dimensional gas chromatography and structure-activity modeling for screening and preliminary risk assessment of organic contaminants in soil, sediment, and surface water

Energy Technology Data Exchange (ETDEWEB)

Moreira Bastos, Patricia; Haglund, Peter [Umeaa Univ. (Sweden). Dept. of Chemistry

2012-08-15

Purpose: This article aims to investigate the use and benefits of using comprehensive two-dimensional gas chromatography (GC x GC) and structure-activity relationship modeling for screening and prioritization of organic contaminants in complex matrices. The benefit of applying comprehensive screening techniques to samples with high organic contaminant content is primarily that compounds with diverse physicochemical properties can be analyzed simultaneously. Here, a heavily contaminated industrial area was surveyed for organic pollutants by analyzing soil, sediment, and surface water samples. The hazard of the pollutants were ranked using SARs. Material and methods: The water samples were liquid-liquid extracted using dichloromethane and directly analyzed by GC x GC-time-of-flight mass spectrometry (GC x GC-TofMS). Soil and sediment samples were extracted with dichloromethane in an ultrasonic bath and subjected to gel permeation chromatography to eliminate lipids and humic matter. The low molecular weight fraction was then analyzed with GC x GC-TofMS. Results and discussion: More than 10,000 components were found in each sample, of which ca. 300 individual compounds were unambiguously identified using the National Institute of Standards and Technology mass spectra library and authentic reference standards. Alkanes, polycyclic aromatic hydrocarbons, and phthalates were generally the most abundant and were found in all matrices. In contrast, chlorinated compounds such as chlorophenols, biphenyls, and chlorinated pesticides were only detected in samples from a few hotspot regions. The toxicities of the most frequently detected compounds and of the compounds detected at the highest concentrations in samples from hotspot regions were estimated by ecological structure-activity relationships. The ratio of the measured concentration to the predicted toxicity level was then calculated for each compound and used for an initial risk assessment in order to prioritize compounds

Contribution to immersed arc plasma study: applications to organic aqueous effluent decontamination and gasification

International Nuclear Information System (INIS)

Boudesocque, N.

2007-07-01

This work is concerned with decontamination and gasification of aqueous organic liquid waste by immersed thermal plasma technology. In this concept, the organic compounds are decomposed into gas by high temperature plasma. A quench of about 107-108 K/s, is obtained by immersion into a given effluent. Two kinds of arc plasma are studied. The first one is an immersed electrical arc stricken between two graphite electrodes. The second one is a plasma jet generated by a non-transferred plasma torch. For dilute liquid waste (1 g/L) containing molecules incompatible with conventional biological processes, the hydroxyl radicals (OH 0 ) are continuously produced by the plasma jet directly into the solution allowing complete molecule mineralization into carbon dioxide and water. The hetero-atoms, if present, are converted into solvated ions. The decomposition of the molecules, such as chloro-phenols and aniline, are studied. Considering the identified intermediate products, a reaction mechanism is proposed. For each tested molecules, their concentration decreased at least of 90 percent. Based on the 'gasosiphon' phenomenon, the experimental reactor insures the simultaneous recirculation of both gas and liquid phases. The hydrodynamic was studied using in situ high frequency imaging technology. A CFD code was applied for numerical simulation of the observed recirculation phenomena. The results were compared with obtained experimental data. In the case of concentrated liquid waste (≥ 100 g/L), syngas was produced by thermal cracking of organic molecules. The best measured composition of the gas is about 45% v/v of H 2 and 45 % v/v of CO when an electrical arc is used. The usability of both studied plasma types were investigated in this field. The experimental study was carried on using fructose and glucose solution (several hundreds g/L) as surrogated effluent. With a specific injection method, gasification rate is about 30 % with one way. Optical Emission Spectroscopy and

Simultaneous Decolorization and Biohydrogen Production from Xylose by Klebsiella oxytoca GS-4-08 in the Presence of Azo Dyes with Sulfonate and Carboxyl Groups

Science.gov (United States)

Cao, Ming-yue; Wang, Peng-tao; Wang, Shi; Yue, Ying-rong; Yuan, Wen-duo; Qiao, Wei-chuan; Wang, Fei

2017-01-01

ABSTRACT Biohydrogen production from the pulp and paper effluent containing rich lignocellulosic material could be achieved by the fermentation process. Xylose, an important hemicellulose hydrolysis product, is used less efficiently as a substrate for biohydrogen production. Moreover, azo dyes are usually added to fabricate anticounterfeiting paper, which further increases the complexity of wastewater. This study reports that xylose could serve as the sole carbon source for a pure culture of Klebsiella oxytoca GS-4-08 to achieve simultaneous decolorization and biohydrogen production. With 2 g liter−1 of xylose as the substrate, a maximum xylose utilization rate (URxyl) and a hydrogen molar yield (HMY) of 93.99% and 0.259 mol of H2 mol of xylose−1, respectively, were obtained. Biohydrogen kinetics and electron equivalent (e− equiv) balance calculations indicated that methyl red (MR) penetrates and intracellularly inhibits both the pentose phosphate pathway and pyruvate fermentation pathway, while methyl orange (MO) acted independently of the glycolysis and biohydrogen pathway. The data demonstrate that biohydrogen pathways in the presence of azo dyes with sulfonate and carboxyl groups were different, but the azo dyes could be completely reduced during the biohydrogen production period in the presence of MO or MR. The feasibility of hydrogen production from industrial pulp and paper effluent by the strain if the xylose is sufficient was also proved and was not affected by toxic substances which usually exist in such wastewater, except for chlorophenol. This study offers a promising energy-recycling strategy for treating pulp and paper wastewaters, especially for those containing azo dyes. IMPORTANCE The pulp and paper industry is a major industry in many developing countries, and the global market of pulp and paper wastewater treatment is expected to increase by 60% between 2012 and 2020. Such wastewater contains large amounts of refractory contaminants, such

Syntheses and structure characterization of ten acid-base hybrid crystals based on N-containing aromatic brønsted bases and mineral acids

Science.gov (United States)

Lin, Zhihao; Jin, Shouwen; Li, Xiaoliang; Xiao, Xiao; Hu, Kaikai; Guo, Ming; Chi, Xinchen; Liu, Hui; Wang, Daqi

2017-10-01

Cocrystallization of the aromatic brønsted bases with a series of mineral acids gave a total of ten hybrid salts with the compositions: (2-methylquinoline)2: (hydrochloride acid): 3H2O [(HL1)+. (L1)·· (Cl-) · (H2O)3] (1), (6-bromobenzo[d]thiazol-2-amine): (hydrochloride acid) [(HL2)+. (Cl-)] (2), (6-bromobenzo[d]thiazol-2-amine): (nitric acid) [(HL2)+. (NO3-)] (3), (6-bromobenzo[d]thiazol-2-amine): (sulfuric acid) [(HL2)+ · (HSO4)-] (4), (6-bromobenzo[d]thiazol-2-amine): (phosphoric acid) [(HL2)+ · (H2PO4)-] (5), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrochloride acid): 3H2O [(HL3)+ · (Cl-) (H2O)3] (6), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrobromic acid): CH3OH [(HL3)+ · (Br)- · CH3OH] (7), (5,7-dimethyl-1,8-naphthyridine-2-amine): (sulfuric acid): H2O [(HL3)+ · (HSO4)- · H2O] (8), (2-aminophenol): (phosphoric acid) [(HL4)+ · (H2PO4)-] (9), and (2-amino-4-chlorophenol): (phosphoric acid) [(HL5)+ · (H2PO4)-] (10). The ten salts have been characterized by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the ten investigated crystals the ring N of the heterocycle or the NH2 in the aminophenol are protonated when the acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted classical hydrogen bonds between the NH+/NH3+ and deprotonated acidic groups. Further analysis of the crystal packing of the salts indicated that a different family of additional CHsbnd O, CHsbnd Cl, CH3sbnd N, CH3sbnd O, CHsbnd Br, CH3sbnd Br, Brsbnd Cl, Clsbnd S, Osbnd S, Osbnd O, Brsbnd S, Hsbnd H, and π-π associations contribute to the stabilization and expansion of the total high-dimensional frameworks. For the coexistence of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both. Some classical

Persistent organic compounds in food chains in Bavaria and Czechia. Pt. 1. Terrestrial systems; Persistente organische Verbindungen in Nahrungsketten von Bayern und Tschechien. T. 1. Terrestrische Systeme

Energy Technology Data Exchange (ETDEWEB)

Kettrup, A; Heinisch, E

1997-10-01

In the paper presented here single presentations concerning the contamination of soil, vegetation and organs and tissues form animals and man with persistent organic substances (DDT and metabolites, isomers of hexachlorocyclohexane, hexachlorobenzene, cyclodiene insecticides, chlorophenols, light volatile organic compounds, PCDD/F, PAH and nitromusk compounds) from Bavaria, the Czech Republic and Brandenburg/Berlin and the former GDR, respectively, were assessed, summarized and - as far as possible - compared and confronted. The results are given in the summaries of the single chapters. It could be shown that the different socioeconomic structures in the regions upto 1989 has considerable influences on the extent of the contamination. Large corpusses of law concerning the application and production of chemical products and their increasingly denser monitoring in Bavaria as well as the various sanitation measures has lead to only traces of chloroorganic compounds now and to a minimization of unavoidable substances like PCDD/F. These prerequisites have now been created in the new federal states - here the example Brandenburg - where upto 1989 the national economy was only directed at production maximization and they begin to result in a decrease of contamination especially for the classical chlorohydrocarbons. In the Czech Republic there are still mostly considerably higher loads, e.g. for HCB and especially for PCB, leading to the consideration of possible bordercrossing effects. (orig.) [Deutsch] In der vorliegenden Arbeit wurden Einzeldarstellungen zur Kontamination von Boden, Aufwuchs und von Tieren bzw. dem Menschen stammenden Organen und Geweben mit persistenten organischen Verbindungen (DDT und Metabolite, Isomeren des Hexachlorcyclohexans, Hexachlorbenzol, Cyclodien-Insektizide, Chlorphenole, leichtfluechtige organische Verbindungen, PCDD/F, PAK und Nitromoschusverbindungen) aus Bayern, Tschechien und Brandenburg-Berlin bzw. der ehemaligen DDR ausgewertet

Effect of limestone addition on chlorine compound emissions in grate and fluidized-bed combustion of recovered fuels

International Nuclear Information System (INIS)

Vesterinen, R.; Ruuskanen, J.

2000-01-01

The aim was to verify the positive results of laboratory experiments concerning the reducing effect of limestone addition on emissions of organic chlorine compounds and acidifying compounds (HCl, HF, SO 2 ) in grate and fluidized-bed combustion of recovered fuels in commercial boilers. The final aim is to develop a cheap and practical way of reducing emissions of organic chlorine compounds in co-combustion of recovered fuels. Pellets produced from the mixture of recovered fuel and limestone is a product ready for use in plants without any need of additional employees or equipment for limestone feed. Pellets produced by Ewapower Oy are used as recovered fuel and Gotland limestone of Partek Nordkalk Oyj Abp as limestone. Ewapower Oy produces pellets by feeding a certain proportion of limestone among recovered fuel at the production stage. Experiments are carried out in one grate-combustion plant and in one or two fluidized-bed plants. The first experiments were carried out in a 3 MWth BioGrate boiler at the new heating station of Pielavesi municipality in autumn 1999. The flue gases are cleaned with a cyclone (FinCleaner). The main fuel was a mixture of bark and sawdust (3:1) from a sawmill. Ewapower pellets with an addition of Gotland limestone were used as recovered fuel. The experiments were carried out at about 2 MW boiler output. Temperatures of the furnace and flue gas, pressure and fuel gas composition were measured continuously. For determining the composition of gas, O 2 , CO, CO 2 , hydrocarbons and N 2 O(FTIR), NO x and SO 2 were measured continuously. HCl, heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF), polyaromatic hydrocarbons (PAH), chlorobenzenes, chlorophenols and PCB were measured as one-shot determinations. Fuel and ash samples were also collected during the experiments. The organic compounds were analyzed by the Department of Environmental Science of the University of Kuopio, which is

The effect of doping titanium dioxide nanoparticles on phase transformation, photocatalytic activity and anti-bacterial properties

Science.gov (United States)

Buzby, Scott Edward

Nanosized titanium dioxide has a variety of important applications in everyday life including a photocatalyst for pollution remediation, photovoltaic devices, sunscreen, etc. This study focuses on the various properties of titanium dioxide nanoparticles doped with various cation and anion species. Samples were produced by various methods including metalorganic chemical vapor deposition (MOCVD), plasma assisted metalorganic chemical vapor deposition (PA-MOCVD) and sol-gel. Numerous techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy both scanning (SEM) and transmission (TEM) were used for physical characterization. Photocatalytic properties were determined by the oxidation of methylene blue dye and 2-chlorophenol in water as well as gaseous formic acid with results analyzed by high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR) and ultra violet - visible spectroscopy (UV-VIS). For the purpose of enhancement of the photocatalytic activity of titanium dioxide nanoparticles, the effect of anion doping and the anatase-rutile phase ratio were studied. Although anatase, rutile and mixed crystallite phases all show some degree of activity in photocatalytic reactions, these results show that anatase is better suited for the degradation of organic compounds in an aqueous medium any advantage in photocatalytic activity gained through the enhancement in optical response from the smaller band gap by addition of rutile was overcome by the negatives associated with the rutile phase. Furthermore substitutional nitrogen doping showed significant improvement in UV photocatalysis as well as allowing for visible light activation of the catalyst. Further studies on the phase transitions in titanium dioxide nanoparticles were carried out by synthesizing various cation doped samples by sol-gel. Analysis of the phases by XRD showed an inverse relationship between dopant size and rutile percentage

Practical applications of the Fenton reaction to the removal of chlorinated aromatic pollutants. Oxidative degradation of 2,4-dichlorophenol.

Science.gov (United States)

Detomaso, Antonia; Lopez, Antonio; Lovecchio, Giangiuseppe; Mascolo, Giuseppe; Curci, Ruggero

2003-01-01

Chlorophenols (CPs) constitute a group of organic pollutants that are introduced into the environment as a result of several man-made activities, such as uncontrolled use of pesticides and herbicides, and as byproducts in the paper pulp bleaching. Promising removal technologies of chlorinated aromatics consist in the application of advanced oxidation processes (AOPs) that can provide an almost total degradation of a variety of contaminants. Among these, wide application find Fenton systems based on generation of reactive species having a high oxidizing power, such as hydroxyl radical HO*. Our objective was that of determining the overall degradation efficiency of the model compound 2,4-dichlorophenol (DCP) by thermal Fenton-type oxidation systems with a view toward defining in more details relevant process parameters, the effect of reaction temperature and of co-catalyst Cu2+. Reaction conditions were similar to those generally adopted as optimal in many practical applications, i.e. pollutant/Fe2+ (as FeSO4) ratio ca. 20, Fe2+/Cu2+ (co-catalyst) 2:1, pH adjusted and controlled at pH 3, and H2O2 in excess (up to four-fold over the stoichiometric amount required for complete mineralization). The results demonstrate that it is advantageous to carry out the reaction at a temperature markedly higher (70 degrees C) than ambient. The stepwise addition of H2O2 in aliquots yields an efficient transformation, while allowing a convenient control of the reaction exothermicity. Under these conditions, the essentially complete removal of the initial DCP is accomplished using just one equiv of H2O2 during 15 min; excess H2O2 (5 equivalents) yields extensive substrate mineralization. Also relevant, at 70 degrees C dechlorination of the initial DCP (and of derived reaction intermediates) is remarkably extensive (3-5% residual TOX), already with the addition of 1 equiv of H2O2. At the end of the reaction, IC and IC-MS analyses of the solution reveal that only low-molecular weight

Decomposition of halogenated organic chemicals in ionic liquid by ionizing radiation

International Nuclear Information System (INIS)

Kimura, A.; Taguchi, M.; Kojima, T.; Nagaishi, R.; Hiratsuka, H.

2006-01-01

Introduction: Halogenated organic chemicals such as polychlorodibenzo-p-dioxin, polychlorobiphenyls and hexachlorobenzene are widely spread in water environment. These pollutants are persistent against advanced oxidation treatments such as ozone/UV, ozone/hydrogen peroxide, ionizing radiation and photocatalysts. The ionizing radiation, however, can also produce homogeneously and quantitatively reducing species in water. On the other hand, room temperature ionic liquids (RTILs) have unique properties such as nonflammable, high polarity, low melting point, hydrophobicity and wide electrochemical window. The combined method of reduction by ionizing radiation and RTILs is investigated as a new environmental conservation technology. Experimental: Chlorophenol (CP) is selected as model chemicals having the main frame of halogenated organic chemicals. Each o - , m - and p-CP were irradiated with 60 Co γ-ray in each diethylmethyl(2-methoxy-ethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEMMA- TFSI), diethylmethyl(2-methoxyethyl)-ammonium tetrafluoroborate (DEMMA-BF4), methanol and ethanol as solvent. Decomposition of CP and formation of irradiation products were studied using HPLC, LC-MS and ion chromatography. Results and discussion: Concentration of CP in each solution decreased as a function of dose. G-value was estimated from the slope at the primary stage of the decomposition curve. The G(-CP) and G(Phenol) were shown in Table 1. G(-CP) in the aliphatic alcohols was 0.21 to 0.37, which is lower than G-value of reducing species in the alcohols, e.g. G=1.0 to 1.5 for solvated electron. Since the rate constant for reaction of CP with hydrated electron is 1.3 x 10 9 mol -1 ·dm 3 ·s -1 , the reverse reaction is considered to attribute. G(-CP) in DEMMA-TFSI or DEMMA-BF4 was about 2 to 3 times higher than that in each alcohol. Lifetime of the reducing species in RTILs would be longer than that in each alcohol. G(-CP) in DEMMA-TFSI decreased by adding acetone or oxygen

Development of scanning electrochemical microscopy for the investigation of photocatalysis at semiconductor surfaces

International Nuclear Information System (INIS)

Fonseca, Sofia Margarida Martins Costa da

2002-01-01

oxygen concentration at the illuminated TiO 2 surface, which provides a new insight into the photomineralisation process, showing the important role of oxygen in controlling the kinetics. Using an SECM potentiometric approach, the photomineralisation kinetics of a model organic pollutant, 4-chlorophenol (4-CP), in aerated and oxygenated aqueous solutions at supported TiO 2 films, were quantitatively investigated. A potentiometric Ag/AgCI UME, positioned at a known distance above the TiO 2 film, was used to monitor directly the Cl - production from the photomineralisation of 4-CP. A theoretical model, employing a Langmuir-Hinshelwood type kinetic equation, has been developed to interpret the kinetics of the photomineralisation process and determine the associated quantum efficiency. A direct correlation between oxygen consumption at the illuminated TiO 2 surface and Cl - formation in the photomineralisation process has been found. SECM has also been used to monitor photoelectrochemical transfer kinetics at the TiO 2 /aqueous interface using a well-known electron scavenger, methyl viologen. The TiO 2 film was in contact with a solution containing methyl viologen dication (MV 2+ ) as the redox mediator and sodium acetate as the hole scavenger. The chronoamperometric behaviour for MV 2+ reduction was recorded at an UME tip after stepping the light flux at the TiO 2 film from off to on. The rate constants for the reduction process were obtained through a theoretical model based on zero-order kinetics. The substrate generation/ tip collection mode of the SECM was also used to detect the MV 2+ radical cation produced at the TiO 2 surface at the UME tip. (author)

The effect of timing temporary cements to treat induced pulp necrosis in the teeth of dogs Uso do "curativo de demora" em diferentes tempos no tratamento endodôntico de cães com necrose pulpar induzida

Directory of Open Access Journals (Sweden)

Léslie M. Domingues-Falqueiro

2007-02-01

Full Text Available During endodontic therapy (pulpectomy, root canal debridement and root canal filling microbiological management is a major concern. Bacteria present in dentine tubules, apical foramina and apical delta are causally related to failure of the procedure. Studies have shown that during single session endodontic treatment bacteria remain within dental structures. The aim of the present study was to evaluate endodontic treatment performed as two sessions, using temporary endodontic dressing materials for different periods in four groups of experimental dogs. A total of 80 roots of second and third upper premolar teeth and second, third and fourth lower premolar teeth were divided into four groups. The pulp chamber was opened with burrs and the pulp exposed for 60 days to induce pulpal inflammation and necrosis. Groups II, III and IV were treated with calcium hydroxide plus camphorated paramono-chlorophenol (PMCC for 7, 15 and 30 days, respectively. In all groups, the root canals were filled with zinc oxide-eugenol and gutta-percha cones. Clinical and radiographical measurements were performed every 2 weeks. After 60 days a small block section containing the teeth, surrounding periapical tissues and the periodontium was removed for histological and microbiological study. Histological analysis revealed intense inflammatory response in all groups. Microbiological analysis showed microbial reduction inversely proportional to the period of time that the intracanal temporary medicament was left in place.Em um tratamento endodôntico, a microbiota é o ponto primordial a ser levado em consideração, pois as bactérias presentes nos túbulos dentinários, nas foraminas e no delta apical em cães estão relacionadas aos insucessos do procedimento. Estudos revelam que tratamentos realizados em uma única sessão ainda permitem a permanência de bactérias nas estruturas dentárias, portanto propõe-se a execução em duas sessões, com diferentes tempos de

Effect of pentachlorophenol and chemical oxygen demand mass concentrations in influent on operational behaviors of upflow anaerobic sludge blanket (UASB) reactor.

Science.gov (United States)

Shen, Dong-Sheng; He, Ruo; Liu, Xin-Wen; Long, Yan

2006-08-25

Upflow anaerobic sludge blanket (UASB) reactor that was seeded with anaerobic sludge acclimated to chlorophenols was used to investigate the feasibility of anaerobic biotreatment of synthetic wastewater containing pentachlorophenol (PCP) with additional sucrose as carbon source. Two sets of UASB reactors were operated at one time. But the seeded sludge for the two reactors was different and Reactor I was seeded with the sludge that was acclimated to PCP completely for half a year, and Reactor II was seeded with the mixed sludge that was acclimated for half a year to PCP, 4-CP, 3-CP or 2-CP, respectively. The degradation of PCP and the operation fee treating the wastewater are affected by the concentration of MEDS (microorganism easily degradable substrate). So the confirmation of the suitable ratio of [COD] and [PCP] was the key factor of treating the wastewater containing PCP economically and efficiently. During the experiment, the synthetic wastewater with 180.0 mg L(-1) PCP and 1250-10000 mg L(-1) COD could be treated steadily in the experimental Reactor I. The removal efficiency of PCP was more than 99.5% and the removal efficiency of COD was up to 90%. [PCP] (concentration of PCP) in effluent was less than 0.5 mg L(-1). [PCP] in influent could affect proper [COD] (concentration of COD) range in influent that was required for maintenance of steady running of the experimental reactor with a hydraulic retention time (HRT) from 20 to 22 h. [PCP] in influent would directly affect the necessary [COD] in influent when the UASB reactor ran normally and treated the wastewater containing PCP. When [PCP] was 100.4, 151.6 and 180.8 mg L(-1) in influent, respectively, [COD] in influent had to be controlled about 1250-7500, 2500-5000 and 5000 mg L(-1) to maintain the UASB reactor steady running normally and contemporarily ensure that [COD] and [PCP] in effluent were less than 300 and 0.5 mg L(-1), respectively. With the increase of [PCP] in influent, the range of variation

Effect of pentachlorophenol and chemical oxygen demand mass concentrations in influent on operational behaviors of upflow anaerobic sludge blanket (UASB) reactor

International Nuclear Information System (INIS)

Shen Dongsheng; He Ruo; Liu Xinwen; Long Yan

2006-01-01

Upflow anaerobic sludge blanket (UASB) reactor that was seeded with anaerobic sludge acclimated to chlorophenols was used to investigate the feasibility of anaerobic biotreatment of synthetic wastewater containing pentachlorophenol (PCP) with additional sucrose as carbon source. Two sets of UASB reactors were operated at one time. But the seeded sludge for the two reactors was different and Reactor I was seeded with the sludge that was acclimated to PCP completely for half a year, and Reactor II was seeded with the mixed sludge that was acclimated for half a year to PCP, 4-CP, 3-CP or 2-CP, respectively. The degradation of PCP and the operation fee treating the wastewater are affected by the concentration of MEDS (microorganism easily degradable substrate). So the confirmation of the suitable ratio of [COD] and [PCP] was the key factor of treating the wastewater containing PCP economically and efficiently. During the experiment, the synthetic wastewater with 180.0 mg L -1 PCP and 1250-10000 mg L -1 COD could be treated steadily in the experimental Reactor I. The removal efficiency of PCP was more than 99.5% and the removal efficiency of COD was up to 90%. [PCP] (concentration of PCP) in effluent was less than 0.5 mg L -1 . [PCP] in influent could affect proper [COD] (concentration of COD) range in influent that was required for maintenance of steady running of the experimental reactor with a hydraulic retention time (HRT) from 20 to 22 h. [PCP] in influent would directly affect the necessary [COD] in influent when the UASB reactor ran normally and treated the wastewater containing PCP. When [PCP] was 100.4, 151.6 and 180.8 mg L -1 in influent, respectively, [COD] in influent had to be controlled about 1250-7500, 2500-5000 and 5000 mg L -1 to maintain the UASB reactor steady running normally and contemporarily ensure that [COD] and [PCP] in effluent were less than 300 and 0.5 mg L -1 , respectively. With the increase of [PCP] in influent, the range of variation of

Enhancement of in situ Remediation of Hydrocarbon Contaminated Soil

Energy Technology Data Exchange (ETDEWEB)

Palmroth, M.

2006-07-01

Approximately 750 000 sites of contaminated land exist across Europe. The harmful chemicals found in Finnish soils include heavy metals, oil products, polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorophenols, and pesticides. Petroleum and petroleum products enter soil from ruptured oil pipelines, land disposal of refinery products, leaking storage tanks and through accidents. PAH contamination is caused by the spills of coal tar and creosote from coal gasification and wood treatment sites in addition to oil spills. Cleanup of soil by bioremediation is cheaper than by chemical and physical processes. However, the cleaning capacity of natural attenuation and in situ bioremediation is limited. The purpose of this thesis was to find feasible options to enhance in situ remediation of hydrocarbon contaminants. The aims were to increase the bioavailability of the contaminants and microbial activity at the subsurface in order to achieve higher contaminant removal efficiency than by intrinsic biodegradation alone. Enhancement of microbial activity and decrease of soil toxicity during remediation were estimated by using several biological assays. The performance of these assays was compared in order to find suitable indicators to follow the progress of remediation. Phytoremediation and chemical oxidation are promising in situ techniques to increase the degradation of hydrocarbons in soil. Phytoremediation is plant-enhanced decontamination of soil and water. Degradation of hydrocarbons is enhanced in the root zone by increased microbial activity and through the detoxifying enzymes of plants themselves. Chemical oxidation of contaminants by Fenton's reaction can produce degradation products which are more biodegradable than the parent compounds. Fenton's reaction and its modifications apply solutions of hydrogen peroxide and iron for the oxidation of organic chemicals. The cost of oxidation can be reduced by aiming at partial instead of full

Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants?

Science.gov (United States)

Schröder, Peter; Lyubenova, Lyudmila; Huber, Christian

2009-11-01

Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation. Typha latifolia and Phragmites australis plants for the present study were grown under greenhouse conditions in experimental ponds. A Picea abies L. suspension culture was grown in a growth chamber. Cadmium sulphate, sodium arsenate and lead chloride in concentrations from 10 to 500 microM were administered to plants. Enzymes of interest for the present study were: glutathione transferase (GST), glutathione reductase, ascorbate peroxidase and peroxidase. Measurements were performed according to published methods. GST spectrophotometric assays included the model substrates CDNB, DCNB, NBC, NBoC and the herbicide Fluorodifen. Heavy metals lead to visible stress symptoms in higher plants. Besides one long-term experiment of 72 days duration, the present study shows time and concentration-dependent plant alterations already after 24 and 72 h Cd incubation. P. abies spruce cell cultures react to CdSO(4) and Na(2)HAsO(4) with an oxidative burst, similar to that observed after pathogen attack or elicitor treatment. Cd application resulted in a reduction in GSH and GSSG contents. When a heavy metal mixture containing Na(2)HAsO(4), CdSO(4) and PbCl(2) was applied to cultures, both GSH and GSSG levels declined. Incubation with

Authentic Learning Enviroment in Analytical Chemistry Using Cooperative Methods and Open-Ended Laboratories in Large Lecture Courses

Science.gov (United States)

Wright, John C.

1996-09-01

the semester when the first research paper was the Yamazaki et al. "Spectroscopic Determination of pH and Its Application to Determination of Thermodynamic Equilibrium Constants". The project on measuring the pKa of an indicator was a reproduction of the work in the paper with a different indicator. A buffer with a well-known acid dissociation constant was prepared by accurate mixing of appropriate acids and conjugate bases so that pH could be calculated to four significant figures. Accurate absorbance measurements of the acid/conjugate base forms of the indicator then gave accurate values of pKa of the indicator. Different groups in the class measured different indicators and the results were pooled so that students had access to all the information on all the indicators. The development of a spectroscopic pH meter used the database to select a mixture of indicators that would give spectroscopic selectivity for pH over a wide pH range. Example student results are shown in Figures 1 and 2. Figure 1 shows the absorbance spectra of a mixture of thymol blue, methyl orange, phenol red, and chlorophenol red for 8 pH values from 1.5 to 9.4. Figure 1. Spectra of a methyl orange, phenol red, chlorophenol red, thymol blue mixture for a series of pH values. Figure 2 shows a typical fit that was obtained for a pH = 6.3404, along with the contributions from each of the four indicators. Figure 2. Comparison of the theoretical and experimental absorption spectrum for the pH = 6.34 sample in Figure 1 and the contributions to the theoretical spectrum from each of the individual indicators. Table 2 is a compilation of the results for each of the pH values showing the results of a pH meter measurement, a calculated pH based on knowing the buffer mixture, and the pH that resulted from the spectroscopic fitting procedure. There are obvious differences in the three measurements that need further work, but the results also show clearly that the procedure is feasible and good