Persulfate Oxidation Regeneration of Granular Activated Carbon: Reversible Impacts on Sorption Behavior

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Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH < 2) and the accumulation ...

Carbon isotope fractionation of chlorinated ethenes during oxidation by Fe{sup 2+} activated persulfate

Energy Technology Data Exchange (ETDEWEB)

Marchesi, Massimo, E-mail: m2marche@uwaterloo.ca [Departament de Cristallografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Barcelona, Catalunya 08028 (Spain); Earth and Environmental Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Aravena, Ramon [Earth and Environmental Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Sra, Kanwartej S. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada); Thomson, Neil R. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Otero, Neus; Soler, Albert [Departament de Cristallografia, Mineralogia i Diposits Minerals, Universitat de Barcelona, Barcelona, Catalunya 08028 (Spain); Mancini, Silvia [Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada)

2012-09-01

The increased use of persulfate (S{sub 2}O{sub 8}{sup 2-}) for in situ chemical oxidation to treat groundwater and soils contaminated by chlorinated hydrocarbon compounds (CHCs) requires unbiased methods to assess treatment performance. Stable carbon isotope analysis offers a potential tool for assessing the in situ treatment performance of persulfate at sites contaminated with CHCs. This study investigated the extent of C isotope fractionation during oxidation of tetrachloroethene (PCE), trichloroethene (TCE) and cis-dichloroethene (cis-DCE) by persulfate activated by ferrous ion (Fe{sup 2+}). An average carbon isotope enrichment factor {epsilon}{sub bulk} of - 4.9 Per-Mille-Sign for PCE, - 3.6 Per-Mille-Sign for TCE and - 7.6 Per-Mille-Sign for cis-DCE were obtained in batch experiments. Variations in the initial S{sub 2}O{sub 8}{sup 2-}/Fe{sup 2+}/CHC molar ratios did not result in any significant differences in carbon isotope fractionation. The occurrence of carbon isotope fractionation during oxidation and the lack of dependence of enrichment factors upon the S{sub 2}O{sub 8}{sup 2-}/Fe{sup 2+}/CHC molar ratio demonstrate that carbon isotope analysis can potentially be used at contaminated sites as an additional technique to estimate treatment efficacy during oxidation of CHCs by Fe{sup 2+} activated persulfate. Highlights: Black-Right-Pointing-Pointer The performance of in situ chemical oxidation (ISCO) is still difficult to assess. Black-Right-Pointing-Pointer We investigated the potential of carbon isotope analysis as a new assessing tool. Black-Right-Pointing-Pointer C isotope of PCE, TCE and DCE oxidized by persulfate activated by Fe{sup 2+} was measured. Black-Right-Pointing-Pointer Enrichment factors of - 4.9 Per-Mille-Sign for PCE, - 3.6 Per-Mille-Sign for TCE and - 7.6 Per-Mille-Sign for cisDCE were obtained. Black-Right-Pointing-Pointer Carbon isotope can potentially be used to estimate the ISCO treatment efficacy.

Transport and Application of Heat-Activated Persulfate for In-situ Chemical Oxidation of Residual Trichloroethylene

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Quig, L.; Johnson, G. R.

2015-12-01

Persulfate ISCO has been shown to treat a wide range of contaminants. While persulfate ISCO can be tailored to site and pollutant specific characteristics (e.g., activation via energy or catalysis), thermal activation of persulfate is particularly promising as it can be easily controlled and requires no additional reagents. A mechanistic study of the physical and chemical processes controlling the effectiveness of this remedial approach is not well documented in the literature with much therein focused on reactions in batch systems. The purpose of this research was twofold. Initial studies characterized the overall transport behavior of unactivated and thermally-activated persulfate (20, 60, and 90°C) in one-dimensional soil column systems. Finally, experiments were conducted to investigate persulfate ISCO as a remedial approach for residual-phase trichloroethylene (TCE). At all activation temperatures investigated, persulfate exhibited ideal transport behavior in miscible displacement experiments. Moment analysis of persulfate ion breakthrough curves indicated negligible interaction of persulfate with the natural sandy material. Persulfate ISCO for residual-phase TCE was characterized at two flow rates, 0.2 mL/min and 0.5 mL/min, resulting in two degrees of persulfate activation, 39.5% and 24.6%, respectively. Both ISCO soil column systems showed an initial, long-term plateau in effluent TCE concentrations indicating steady-state dissolution of pure phase TCE. Observed effluent concentrations decreased after 75 and 100 pore volumes (normalized for the measured residual NAPL fraction) compared to 110 pore volumes in the control study. Pseudo first-order reaction rate constants for the decreasing TCE concentrations equaled 0.063/hr and 0.083/hr, respectively, compared to 0.041/hr for the control. Moment analysis of the complete dissolution of TCE in the persulfate/activated persulfate remediation systems indicated approximately 33% oxidation of TCE mass present. By

Green mechanochemical oxidative decomposition of powdery decabromodiphenyl ether with persulfate

International Nuclear Information System (INIS)

Huang, Aizhen; Zhang, Zhimin; Wang, Nan; Zhu, Lihua; Zou, Jing

2016-01-01

Highlights: • MC process greatly enhanced the decomposition of PS into reactive sulfate radicals. • The mechanochemical (MC) activation of persulfate was applied to degrade BDE209. • This method could achieve a rapid and complete debromination and mineralization of BDE209. • No toxic low brominated polybrominated diphenyl ethers were produced and accumulated. • Sulfate radicals were the main oxidizing species for the decomposition of BDE209. - Abstract: A method was developed for efficiently degrading powdery decabromodiphenyl ether (BDE209) by using mechanochemical (MC) activation of persulfate (PS). Characteristic Raman spectra of BDE209 corresponding to C−Br and C−O bonds were decreased in intensity and finally disappeared as the MC reaction proceeded. The BDE209 removal was influenced by the molar ratio of PS to BDE209, the mass ratio of milling ball to reaction mixtures, the ball size, and the ball rotation speed. Under optimal conditions, the new method could achieve a complete degradation, debromination and mineralization of BDE209 within 3 h of milling. However, the degradation removal (or debromination efficiency) was decreased to only 51.7% (15.6%) and 67.8% (31.5%) for the use of CaO and peroxymonosulfate, respectively. The analyses of products demonstrated that once the degradation was initiated, BDE209 molecules were deeply debrominated and fully mineralized in the MC-PS system. The strong oxidizing ability of this system was due to the reactive sulfate radicals generated from the MC-enhanced activation of PS, which was confirmed with electron spin resonance spectroscopy. Because no toxic low brominated polybrominated diphenyl ethers were accumulated as byproducts, the proposed MC oxidative degradation method will have promising applications in the treatment of solid BDE209 at high concentrations.

Oxidation of benzoic acid by heat-activated persulfate: Effect of temperature on transformation pathway and product distribution.

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Zrinyi, Nick; Pham, Anh Le-Tuan

2017-09-01

Heat activates persulfate (S 2 O 8 2- ) into sulfate radical (SO 4 - ), a powerful oxidant capable of transforming a wide variety of contaminants. Previous studies have shown that an increase in temperature accelerates the rates of persulfate activation and contaminant transformation. However, few studies have considered the effect of temperature on contaminant transformation pathway. The objective of this study was to determine how temperature (T = 22-70 °C) influences the activation of persulfate, the transformation of benzoic acid (i.e., a model compound), and the distribution of benzoic acid oxidation products. The time-concentration profiles of the products suggest that benzoic acid was transformed via decarboxylation and hydroxylation mechanisms, with the former becoming increasingly important at elevated temperatures. The pathway through which the products were further oxidized was also influenced by the temperature of persulfate activation. Our findings suggest that the role of temperature in the persulfate-based treatment systems is not limited only to controlling the rates of sulfate and hydroxyl radical generation. The ability of sulfate radical to initiate decarboxylation reactions and, more broadly, fragmentation reactions, as well as the effect of temperature on these transformation pathways could be important to the transformation of a number of organic contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Application of persulfate-oxidation foam spraying as a bioremediation pretreatment for diesel oil-contaminated soil.

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Bajagain, Rishikesh; Lee, Sojin; Jeong, Seung-Woo

2018-05-15

This study investigated a persulfate-bioaugmentation serial foam spraying technique to remove total petroleum hydrocarbons (TPHs) present in diesel-contaminated unsaturated soil. Feeding of remedial agents by foam spraying increased the infiltration/unsaturated hydraulic conductivity of reagents into the unsaturated soil. Persulfate mixed with a surfactant solution infiltrated the soil faster than peroxide, resulting in relatively even soil moisture content. Persulfate had a higher soil infiltration tendency, which would facilitate its distribution over a wide soil area, thereby enhancing subsequent biodegradation efficiency. Nearly 80% of soil-TPHs were degraded by combined persulfate-bioaugmentation foam spraying, while bioaugmentation foam spraying alone removed 52%. TPH fraction analysis revealed that the removal rate for the biodegradation recalcitrant fraction (C 18 to C 22 ) in deeper soil regions was higher for persulfate-bioaugmentation serial foam application than for peroxide-bioaugmentation foam application. Persulfate-foam spraying may be superior to peroxide for TPH removal even at a low concentration (50 mN) because persulfate-foam is more permeable, persistent, and does not change soil pH in the subsurface. Although the number of soil microbes declines by oxidation pretreatment, bioaugmentation-foam alters the microbial population exponentially. Copyright © 2018 Elsevier Ltd. All rights reserved.

Exploring the Role of Persulfate in the Activation Process: Radical Precursor Versus Electron Acceptor.

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Yun, Eun-Tae; Yoo, Ha-Young; Bae, Hyokwan; Kim, Hyoung-Il; Lee, Jaesang

2017-09-05

This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe 0 ) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe 0 (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation). A distinction between degradative reaction mechanisms of the nFe 0 /oxyanion and CNT/oxyanion systems was made in terms of the oxyanion consumption efficacy, radical scavenging effect, and EPR spectral analysis. Statistical study of substrate-specificity and product distribution implied that the reaction route induced on nFe 0 varies depending on the oxyanion (i.e., oxyanion-derived radical), whereas the similar reaction pathway initiates organic oxidation in the CNT/oxyanion system irrespective of the oxyanion type. Chronoamperometric measurements further confirmed electron transfer from organics to oxyanions in the presence of CNTs, which was not observed when applying nFe 0 instead.

Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products.

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Liu, Haizhou; Bruton, Thomas A; Li, Wei; Buren, Jean Van; Prasse, Carsten; Doyle, Fiona M; Sedlak, David L

2016-01-19

Sulfate radical (SO4(•-)) is a strong, short-lived oxidant that is produced when persulfate (S2O8(2-)) reacts with transition metal oxides during in situ chemical oxidation (ISCO) of contaminated groundwater. Although engineers are aware of the ability of transition metal oxides to activate persulfate, the operation of ISCO remediation systems is hampered by an inadequate understanding of the factors that control SO4(•-) production and the overall efficiency of the process. To address these shortcomings, we assessed the stoichiometric efficiency and products of transition metal-catalyzed persulfate oxidation of benzene with pure iron- and manganese-containing minerals, clays, and aquifer solids. For most metal-containing solids, the stoichiometric efficiency, as determined by the loss of benzene relative to the loss of persulfate, approached the theoretical maximum. Rates of production of SO4(•-) or hydroxyl radical (HO(•)) generated from radical chain reactions were affected by the concentration of benzene, with rates of S2O8(2-) decomposition increasing as the benzene concentration increased. Under conditions selected to minimize the loss of initial transformation products through reaction with radicals, the production of phenol only accounted for 30%-60% of the benzene lost in the presence of O2. The remaining products included a ring-cleavage product that appeared to contain an α,β-unsaturated aldehyde functional group. In the absence of O2, the concentration of the ring-cleavage product increased relative to phenol. The formation of the ring-cleavage product warrants further studies of its toxicity and persistence in the subsurface.

Oxidative Decarboxylation of Levulinic Acid by Silver(I/Persulfate

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Yan Gong

2011-03-01

Full Text Available The oxidative decarboxylation of levulinic acid (LA by silver(I/persulfate [Ag(I/S2O82−] has been investigated in this paper. The effects of buffer solution, initial pH value, time and temperature and dosages of Ag(I/S2O82− on the decarboxylation of LA were examined in batch experiments and a reaction scheme was proposed on basis of the reaction process. The experimental results showed that a solution of NaOH-KH2PO4 was comparatively suitable for the LA decarboxylation reaction by silver(I/persulfate. Under optimum conditions (temperature 160 °C, pH 5.0, and time 0.5 h, the rate of LA conversion in NaOH-KH2PO4 solutions with an initial concentration of 0.01 mol LA reached 70.2%, 2-butanone (methyl ethyl ketone was the single product in the gas phase and the resulted molar yield reached 44.2%.

Electrokinetic delivery of persulfate to remediate PCBs polluted soils: effect of injection spot.

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Fan, Guangping; Cang, Long; Fang, Guodong; Qin, Wenxiu; Ge, Liqiang; Zhou, Dongmei

2014-12-01

Persulfate-based in situ chemical oxidation (ISCO) is a promising technique for the remediation of organic compounds contaminated soils. Electrokinetics (EK) provides an alternative method to deliver oxidants into the target zones especially in low permeable-soil. In this study, the flexibility of delivering persulfate by EK to remediate polychlorinated biphenyls (PCBs) polluted soil was investigated. 20% (w/w) of persulfate was injected at the anode, cathode and both electrodes to examine its transport behaviors under electrical field, and the effect of field inversion process was also evaluated. The results showed that high dosage of persulfate could be delivered into S4 section (near cathode) by electroosmosis when persulfate was injected from anode, 30.8% of PCBs was removed from the soil, and the formed hydroxyl precipitation near the cathode during EK process impeded the transportation of persulfate. In contrast, only 18.9% of PCBs was removed with the injection of persulfate from cathode, although the breakthrough of persulfate into the anode reservoir was observed. These results indicated that the electroosmotic flow is more effective for the transportation of persulfate into soil. The addition of persulfate from both electrodes did not significantly facilitate the PCBs oxidation as well as the treatment of electrical field reversion, the reinforced negative depolarization function occurring in the cathode at high current consumed most of the oxidant. Furthermore, it was found that strong acid condition near the anode favored the oxidation of PCBs by persulfate and the degradation of PCBs was in consistent with the oxidation of Soil TOC in EK/persulfate system. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

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

2016-02-01

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

Optimization of stabilized leachate treatment using ozone/persulfate in the advanced oxidation process

International Nuclear Information System (INIS)

Abu Amr, Salem S.; Aziz, Hamidi Abdul; Adlan, Mohd Nordin

2013-01-01

Highlights: ► Ozone and persulfate reagent (O 3 /S 2 O 8 2- ) was used to treat stabilized leachate. ► Central composite design (CCD) with response surface methodology (RSM) was applied. ► Operating variables including ozone and persulfate dosage, pH variance, and reaction time. ► Optimum removal of COD, color, and NH 3 –N was 72%, 96%, and 76%, respectively. ► A good value of ozone consumption (OC) obtained with 0.60 (kg O 3 /kg COD). - Abstract: The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities ( 3 –N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m 3 ozone, 1 g/1 g COD 0 /S 2 O 8 2- ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH 3 –N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O 3 /kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S 2 O 8 2- only, to evaluate its effectiveness. The combined method (i.e., O 3 /S 2 O 8 2- ) achieved higher removal efficiencies for COD, color, and NH 3 –N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate

Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon

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Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2–persulfate binary mixtur...

Remediation of total petroleum hydrocarbons using combined in-vessel composting ‎and oxidation by activated persulfate

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A.R. Asgari

2017-12-01

Full Text Available This study was investigated the efficiency of activated persulfate and ‎in-vessel composting for removal of total petroleum hydrocarbons. ‎Remediation by activated persulfate with ferrous sulfate as pre-treatment was done at batch system. In the chemical oxidation, various variables including persulfate concentrations (10-3000 mg/g as waste, pH (3-7, ferrous sulfate (0.5-4 mg/g as wasteand temperature (20-60°C were studied. In the biological system, premature compost was added as an amendment. The filter cake to compost ratio were 1:0 (as control and 1:5 to 15 (as dry basis. C: N: P ratio and moisture content were 100:5:1 and 45-60%, respectively. The results showed that acidic pH (pH=3 had high efficiency for the removal of total petroleum hydrocarbons by activated persulfate. Temperature had the significant effect during the persulfate oxidation. When ferrous sulfate was used as an activator for degradation at acidic condition and 60°C, removal efficiency increased to 47.32%. The results of biological process showed that the minimum total petroleum hydrocarbons removal in all reactors was 62 percent. The maximum and minimum removal efficiency was obtained at 1:5 (69.46% and 1:10 (62.42% mixing ratios, respectively. Kinetic study showed that second order kinetic model (R2>0.81 shows the best agreement with the experimental data and the rate of TPH degradation at low mixing ratio (1:3 was faster than high mixing ratio (1:15. Therefore, according to the results, in-vessel composting after pre-treatment by activated persulfate is suggested as an efficient process for degradation of total petroleum hydrocarbons.

Oxidation of the odorous compound 2,4,6-trichloroanisole by UV activated persulfate: Kinetics, products, and pathways.

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Luo, Congwei; Jiang, Jin; Ma, Jun; Pang, Suyan; Liu, Yongze; Song, Yang; Guan, Chaoting; Li, Juan; Jin, Yixin; Wu, Daoji

2016-06-01

The transformation efficiency and products of an odorous compound 2,4,6-trichloroanisole (TCA) at the wavelength of 254 nm in the presence of persulfate were investigated for the first time. The effects of water matrix (i.e., natural organic matter (NOM), pH, carbonate/bicarbonate (HCO3(-)/CO3(2-)), and chloride ions (Cl(-))) were evaluated. The second order rate constant of TCA reacting with sulfate radical (SO4(-)) was determined to be (3.72 ± 0.10) × 10(9) M(-1) s(-1). Increasing dosage of persulfate increased the observed pseudo-first-order rate constant for TCA degradation (kobs), and the contribution of SO4(-) to TCA degradation was much higher than that of HO at each experimental condition. Degradation rate of TCA decreased with pH increasing from 4.0 to 9.0, which could be explained by the lower radical scavenging effect of dihydrogen phosphate than hydrogen phosphate in acidic condition (pH kinetic results could be described by a steady-state kinetic model. Furthermore, liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry at powerful precursor ion scan approach was used to selectively detect oxidation products of TCA. It was found that 2,4,6-trichorophenol (TCP) was the major oxidation product (i.e., the initial yield of TCP was above 90%). The second order rate constant between TCP and SO4(-) was estimated to be (4.16 ± 0.20) × 10(9) M(-1) s(-1). In addition, three products (i.e., 2,6-dichloro-1,4-benzoquinone and two aromatic ring-opening products) were detected in the reaction of TCP with SO4(-), which also appeared in the oxidation of TCA in the UV/persulfate process. A tentative pathway was proposed, where the initial one-electron oxidation of TCA by SO4(-) and further reactions (e.g., ipso-hydroxylation and aromatic ring-cleavage) of the formed cation intermediate TCA were involved. Copyright © 2016. Published by Elsevier Ltd.

Efficient degradation of trichloroethylene in water using persulfate activated by reduced graphene oxide-iron nanocomposite.

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Ahmad, Ayyaz; Gu, Xiaogang; Li, Li; Lv, Shuguang; Xu, Yisheng; Guo, Xuhong

2015-11-01

Graphene oxide (GO) and nano-sized zero-valent iron-reduced graphene oxide (nZVI-rGO) composite were prepared. The GO and nZVI-rGO composite were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The size of nZVI was about 6 nm as observed by TEM. The system of nZVI-rGO and persulfate (PS) was used for the degradation of trichloroethylene (TCE) in water, and showed 26.5% more efficiency as compared to nZVI/PS system. The different parameters were studied to determine the efficiency of nZVI-rGO to activate the PS system for the TCE degradation. By increasing the PS amount, TCE removal was also improved while no obvious effect was observed by varying the catalyst loading. Degradation was decreased as the TCE initial concentration was increased from 20 to 100 mg/L. Moreover, when initial solution pH was increased, efficiency deteriorated to 80%. Bicarbonate showed more negative effect on TCE removal among the solution matrix. To better understand the effects of radical species in the system, the scavenger tests were performed. The •SO4(-) and •O2(-) were predominant species responsible for TCE removal. The nZVI-rGO-activated PS process shows potential applications in remediation of highly toxic organic contaminants such as TCE present in the groundwater. Graphical abstract Persulfate activated by reduced graphene oxide and nano-sized zero-valent iron composite can be used for efficient degradation of trichloroethylene (TCE) in water.

Changes in activation energy and kinetics of heat-activated persulfate oxidation of phenol in response to changes in pH and temperature.

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Ma, Jie; Li, Haiyan; Chi, Liping; Chen, Hongkun; Chen, Changzhao

2017-12-01

Persulfate (peroxydisulfate, S 2 O 8 2- ) is the newest oxidant used for the in situ chemical oxidation (ISCO) remediation of soil and groundwater. The present study investigated impacts of solution pH, temperature, and persulfate concentration on the reaction rate constant (k 1 ), activation energy (E a ), and reaction order of the heat-activated persulfate process. Phenol was chosen as the model organic contaminant. As temperature increased from 30 °C to 70 °C, k 1 exhibited a significant increase from 0.003 h -1 ∼0.962 h -1 (pH 1.3-13.9) to 1.184 h -1 ∼9.91 h -1 (pH 1.3-13.9), which corroborated with the activation of persulfate using heat. As pH increased from 1.3 to 13.9, k 1 exhibited a 4.3-fold increase at 70 °C and a 320-fold increase at 30 °C, thereby suggesting that: 1) the phenol oxidation rate increased under alkaline conditions, and 2) the enhancement of reaction rate due to alkaline activation was more pronounced at a lower temperature. Increasing pH significantly reduced E a from 139.7 ± 1.3 kJ/mol at pH 1.3 to 52.0 ± 3.3 kJ/mol at pH 13.9. In contrast to changing pH, increasing persulfate concentration from 20 to 320 mM significantly increased k 1 but did not affect E a . Changes in E a suggest that persulfate oxidation of phenol experienced different reaction pathways or elementary reaction sequences as the pH changed from 1.3 to 13.9. In addition, the k 1 and E a data also suggest that a minimal pH threshold of ∼11 was required for the effective alkaline activation of persulfate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the Removal of Hydrocarbons from Soil Media Using Persulfate Oxidation in the Presence of Mineral Siderite

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Farzad Mohammadi

2016-09-01

Full Text Available Introduction and purpose: Soil contamination by petroleum is mostly resulted from oil exploration, refining processes, leaking of oil products from storage tanks, leaking from pipelines due to pipe friction and decay, refinery wastewater discharge and agricultural irrigation with such materials. Sodium persulfate (Na2S2O8, which is a chemical oxidant, could be activated in the presence of ferrous (Fe2+ and, leading to the treatment of a wide range of soil contaminants. Therefore, this study aimed to evaluate the removal of hydrocarbons from soil media using persulfate oxidation in the presence of mineral siderite. Methods: Initially, oil-contaminated soil was prepared in the form of two separate samples, including silt-clay and sandy-loam soils, which were orderly spiked with 5000 mg fuel oil per kilogram of dry soil. Following that, the effects of various factors, such as different concentrations of persulfate (100-500 mmol/L and siderite (0.1-0.5 g/L, pH (3-9 and temperature (20-60◦C and the removal of petroleum hydrocarbon were assessed.Results: In this study, the optimum condition for degeneration of total petroleum hydrocarbon in silt-clay soils was reported, as follows: temperature: 60◦C, pH: 3, and persulfate/siderite molar ratio of 400 mmol/L to 4.0 g/L. Meanwhile, the optimum condition for the removal of hydrocarbon from sandy-loam soils was pH: 3, temperature: 60◦C and persulfate/siderite molar ratio of 300 mmol/L to 3.0 g/L.Conclusion: According to the results of this study, the optimal amount of persulfate and siderite could be used to remove hydrocarbons from contaminated soils.

Pilot Field Test of Electrokinetically-Delivered and Thermally Activated Persulfate (EKTAP) for Remediation of Chlorinated Solvents in Clay

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O'Carrol, D. M.; Head, N.; Chowdhury, A. I.; Inglis, A.; Garcia, A. N.; Reynolds, D. A.; Hayman, J.; Hogberg, D.; Austrins, L. M.; Sidebottom, A.; Auger, M.; Eimers, J.; Gerhard, J.

2017-12-01

Remediation of low-permeability soils that are contaminated with chlorinated solvents is challenging. In-situ chemical oxidation (ISCO) with persulfate is promising, however, the delivery of the oxidant by hydraulic gradient is limited in low-permeability soils. Electrokinetic (EK) enhanced transport of amendments has shown the potential to overcome these limitations. In particular, the combined technology of EK-delivered and thermally activated persulfate (EKTAP) has been recently demonstrated in the laboratory as promising in these challenging environments (Chowdhury A. I. (2016) Hydraulic and Electrokinetic Delivery of Remediants for In-situ Remediation. Electronic Thesis and Dissertation Repository, Paper 4135). This study presents the first pilot field test to evaluate EKTAP to enhance the distribution and effectiveness of persulfate in clayey soil. The pilot field test was conducted at a contaminated site formerly occupied by a chlorinated solvent production facility. In the EK transport phase, 925 L of 40 g/L persulfate was injected over 57 days, during which 9A of direct current (DC) was applied between two electrodes spaced 3 m apart. In the subsequent heating phase, 10A of alternate current (AC) was applied across the same electrodes for an additional 70 days. Extensive sampling of soil and groundwater in this EKTAP cell were compared to those from two parallel control cells, one with EK only and one with no electrodes. Results indicated that EK can significantly increase transport rates of persulfate in clayey soil. Persulfate activation primarily occurred in the period of DC application, indicating that the natural reduction capacity of the clay soil had a significant impact on persulfate decomposition. Temperature mapping indicated that AC current was able to increase soil temperatures, validating the EKTAP concept. Degradation of chlorinated compounds, in particular, 1-2, dichloroethane (1,2- DCA), was observed to be substantial in areas of persulfate

Decolorization of Methylene Blue by Persulfate Activated with FeO Magnetic Particles.

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Hung, Chang-Mao; Chen, Chiu-Wen; Liu, Yi-Yuan; Dong, Cheng-Di

2016-08-01

In this study, the degradation of methylene blue (MB) was conducted to evaluate the feasibility of using persulfate oxidation activated with iron oxide (FeO) magnetic particles. The results demonstrated that the decolorization rate of MB increased with increasing FeO concentration, exhibiting maximum efficiency at pH0 3.0. The kinetics of MB was studied in the binary FeO catalyst and persulfate oxidation system. The surface properties of FeO before and after reaction was analyzed using cyclic voltammogram (CV), three-dimensional excitation-emission fluorescence matrix (EEFM) spectroscopy, zeta potential, particle size distribution measurements, X-ray diffraction (XRD) and environmental scanning electron microscopy-energy dispersive X-ray spectrometry (ESEM-EDS). The CV data indicated that a reversible redox reaction holds the key to explaining the significant activity of the catalyst. EEFM was used to evaluate the catalyst yield of FeO by fluorescence intensity plots with excitation/emission at 220/300 nm and 260/300 nm. The XRD and ESEM-EDS results confirmed the presence of FeO in the catalyst.

Microcystis aeruginosa-laden water treatment using enhanced coagulation by persulfate/Fe(II), ozone and permanganate: Comparison of the simultaneous and successive oxidant dosing strategy.

Science.gov (United States)

Liu, Bin; Qu, Fangshu; Chen, Wei; Liang, Heng; Wang, Tianyu; Cheng, Xiaoxiang; Yu, Huarong; Li, Guibai; Van der Bruggen, Bart

2017-11-15

In this study, the application of enhanced coagulation with persulfate/Fe(II), permanganate and ozone for Microcystis-laden water treatment was investigated. Two oxidant dosage strategies were compared in terms of the organic removal performance: a simultaneous dosing strategy (SiDS) and a successive dosing strategy (SuDS). To optimize the oxidant species, oxidant doses and oxidant dosage strategy, the zeta potential, floc size and dimension fraction, potassium release and organic removal efficiency during the coagulation of algae-laden water were systematically investigated and comprehensively discussed. Ozonation causes most severe cell lysis and reduces organic removal efficiency because it releases intracellular organics. Moreover, ozonation can cause the release of odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). With increasing doses, the performance of pollutant removal by coagulation enhanced by persulfate/Fe(II) or permanganate did not noticeably improve, which suggests that a low dosage of persulfate/Fe(II) and permanganate is the optimal strategy to enhance coagulation of Microcystis-laden water. The SiDS performs better than the SuDS because more Microcystis cell lysis occurs and less DOC is removed when oxidants are added before the coagulants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Treatment of PAH-contaminated soil using cement-activated persulfate.

Science.gov (United States)

Ma, Fujun; Zhang, Qian; Wu, Bin; Peng, Changsheng; Li, Ning; Li, Fasheng; Gu, Qingbao

2018-01-01

In this study, a novel method for the treatment of polycyclic aromatic hydrocarbon -contaminated soil using cement-activated persulfate was developed. The removal of PAHs in soil rose with increasing initial persulfate concentration, initial Portland cement (PC) concentration, and oxidation reaction time. At an initial persulfate and PC concentration of 19.20 mmol/kg and 10% of soil weight and a reaction time of 2 h, the removal rate of PAHs reached 57.3%. Residual PAHs were mainly adsorbed within the soil granules and thus became less available. The mechanism of PC facilitating the oxidation reaction was that PC addition can increase the pH and temperature of the system. When the soil was stabilized/solidified by 10% of PC, the leaching concentration of PAHs and TOC was significantly higher than that leached from untreated soil. Persulfate oxidation decreased the leaching concentration of PAHs but increased the leaching concentration of TOC in solidification/stabilization products. The addition of activated carbon can decrease the leaching concentrations of both PAHs and TOC. Freeze-thaw durability tests revealed that the leachability of PAHs was not affected by freeze-thaw cycles. The unconfined compressive strength (UCS) of treated soil samples after 12 freeze-thaw cycles was only 49.0% of that curing for 52 days, but the UCS was still > 1 MPa. The treated soil samples can resist disintegration during the process of freeze-thaw cycles.

Persulfate activation by iron oxide-immobilized MnO2 composite: identification of iron oxide and the optimum pH for degradations.

Science.gov (United States)

Jo, Young-Hoon; Do, Si-Hyun; Kong, Sung-Ho

2014-01-01

Iron oxide-immobilized manganese oxide (MnO2) composite was prepared and the reactivity of persulfate (PS) with the composite as activator was investigated for degradation of carbon tetrachloride and benzene at various pH levels. Brunauer-Emmett-Teller (BET) surface area of the composite was similar to that of pure MnO2 while the pore volume and diameter of composite was larger than those of MnO2. Scanning electron microscopy couples with energy dispersive spectroscopy (SEM-EDS) showed that Fe and Mn were detected on the surface of the composite, and X-ray diffraction (XRD) analysis indicated the possibilities of the existence of various iron oxides on the composite surface. Furthermore, the analyses of X-ray photoelectron (XPS) spectra revealed that the oxidation state of iron was identified as 1.74. In PS/composite system, the same pH for the highest degradation rates of both carbon tetrachloride and benzene were observed and the value of pH was 9. Scavenger test was suggested that both oxidants (i.e. hydroxyl radical, sulfate radical) and reductant (i.e. superoxide anion) were effectively produced when PS was activated with the iron-immobilized MnO2. Copyright © 2013 Elsevier Ltd. All rights reserved.

Anaphylaxis, contact urticaria, and allergic asthma caused by persulfates in hair bleaching products

NARCIS (Netherlands)

Hoekstra, Miriam; Schuttelaar, M.L.; Coenraads, P.J.

2010-01-01

Background: Persulfate salts are potent oxidizing agents in hair bleach products that accelerate the bleaching process. Ammonium and potassium persulfates may cause delayedtype and immediate skin reactions. Also allergic asthma and rhinitis have been described. Objectives: Ammonium and potassium

Optimization of Aqueous Phenol Treatment with Persulfate in the Presence of Iron

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somayeh shahsavan

2016-01-01

Full Text Available Phenolic compounds are among the priority pollutants due to their adverse effects on human health and other living organisms. Advanced Oxidation Processes (AOPs offer promising prospects for the removal of pollutants in water and wastewater due to their high efficiency as well as acceptable health and environmental effects. Persulfate, especially when used with iron, is far stronger than many other oxidants with respect to oxidation properties since it produces sulfate radicals which create a higher oxidation potential. In this research, efforts have been made to achieve the best conditions for phenol removal from aqueous environments by activating persulfate with iron ions. The experimental design was accomplished using the Taguchi statistical method and the Minitab 16 software. For the purposes of this study, four factors, each with five levels, were considered to determine the optimal conditions for phenol removal. The optimum conditions for phenol removal by integrated persulfate/iron ions were found to comprise a contact time of 120 minutes, a persulfate/iron molar ratio of 5/4, and PH=3. Phenol removal efficiencies of 94.93%±0.708 and 58.21%±0.675 were obtained under the optimum conditions for the experimental minimum (50 mg/l and maximum (750 mg/l phenol concentrations, respectively. The results revealed that among the parameters affecting the process, environmental pH with 54.80% and persulfate concentration with 11.05% have the highest and lowest effects, respectively. It is expected that this process is also capable of removing phenol from industrial wastewaters with removal efficiencies in the range of 59‒95%.

Effective treatment of oily scum via catalytic wet persulfate oxidation process activated by Fe2.

Science.gov (United States)

Yuan, Xingzhong; Guan, Renpeng; Wu, Zhibin; Jiang, Longbo; Li, Yifu; Chen, Xiaohong; Zeng, Guangming

2018-04-05

Oily scum, a hazardous by-product of petroleum industry, need to be deposed urgently to reduce environmental risks. This paper introduces catalytic wet persulfate oxidation (CWPO) process in the treatment of oily scum to realize risk relief. Under the activation of heat and Fe 2+ , persulfate (PS) was decomposed into sulfate radicals and hydroxyl radicals, which played a major role on the degradation of petroleum hydrocarbons. The effects of wet air oxidation (WAO) and CWPO process on the degradation of oily scum were compared. In CWPO process, the total petroleum hydrocarbons (TPHs) content of oily scum was decreased from 92.63% to 16.75%, which was still up to 70.19% in WAO process. The degradation rate of TPHs in CWPO process was about 3.38 times higher than that in WAO process. The great performance of CWPO process was also confirmed by elemental analysis, which indicated that the C and H contents of oily scum were reduced significantly by CWPO process. These results indicated that CWPO process has high potential on the degradation of oily scum for environmental protection. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhanced Reactant-Contaminant Contact through the Use of Persulfate In Situ Chemical Oxidation (ISCO)

Science.gov (United States)

2011-02-01

248  Figure 7.4.1.5. Concentration versus depth profile for diffusion of 1 M persulfate in kaolin at...Figure 7.4.1.6. Concentration versus depth profile for diffusion of 0.1 M persulfate in kaolin at 82 days...acid. The complex chemistry of persulfate may change the permeability of soils and subsurface solids by inducing dispersion and flocculation, or by

Electrolytic Manipulation of Persulfate Reactivity by Iron Electrodes for TCE Degradation in Groundwater

Science.gov (United States)

Yuan, Songhu; Liao, Peng; Alshawabkeh, Akram N.

2014-01-01

Activated persulfate oxidation is an effective in situ chemical oxidation process for groundwater remediation. However, reactivity of persulfate is difficult to manipulate or control in the subsurface causing activation before reaching the contaminated zone and leading to a loss of chemicals. Furthermore, mobilization of heavy metals by the process is a potential risk. An effective approach using iron electrodes is thus developed to manipulate the reactivity of persulfate in situ for trichloroethylene (TCE) degradation in groundwater, and to limit heavy metals mobilization. TCE degradation is quantitatively accelerated or inhibited by adjusting the current applied to the iron electrode, following k1 = 0.00053•Iv + 0.059 (−122 A/m3 ≤ Iv ≤ 244 A/m3) where k1 and Iv are the pseudo first-order rate constant (min−1) and volume normalized current (A/m3), respectively. Persulfate is mainly decomposed by Fe2+ produced from the electrochemical and chemical corrosion of iron followed by the regeneration via Fe3+ reduction on the cathode. SO4•− and •OH co-contribute to TCE degradation, but •OH contribution is more significant. Groundwater pH and oxidation-reduction potential can be restored to natural levels by the continuation of electrolysis after the disappearance of contaminants and persulfate, thus decreasing adverse impacts such as the mobility of heavy metals in the subsurface. PMID:24328192

Persulfate injection into a gasoline source zone

Science.gov (United States)

Sra, Kanwartej S.; Thomson, Neil R.; Barker, Jim F.

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O82 -, SO42 -, Na+, dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for > 10 months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in M indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M increased by > 100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone.

Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon

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Fenton- or persulfate-driven chemical oxidation regeneration of spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto GAC and chemical oxidation regeneration of the spent-GAC. Environmental...

Persulfate injection into a gasoline source zone.

Science.gov (United States)

Sra, Kanwartej S; Thomson, Neil R; Barker, Jim F

2013-07-01

One pore volume of unactivated sodium persulfate was delivered into an emplaced gasoline residual source zone at CFB Borden. Concentrations of inorganic species (S2O8(2-), SO4(2-), Na(+), dissolved inorganic carbon (DIC)) and selected gasoline compounds (benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene) were monitored across a transect equipped with 90 multilevel sampling points for >10months post-injection. Mass loading (M˙) of compounds constructed from the transect data was used for assessment purposes. Breakthrough of inorganic species was observed when the injection slug crossed the monitoring transect. An increase in [Formula: see text] indicated persulfate consumption during oxidation of gasoline compounds or degradation due to the interaction with aquifer materials. M˙DIC increased by >100% suggesting some mineralization of gasoline compounds during treatment. Mass loading for all the monitored gasoline compounds reduced by 46 to 86% as the inorganic slug crossed the monitoring transect. The cumulative mass discharge across the monitoring transect was 19 to 58% lower than that expected without persulfate injection. After the inorganic injection slug was flushed from the source zone a partial rebound (40 to 80% of baseline levels) of mass discharge of the monitored gasoline compounds was observed. The ensemble of data collected provides insight into the fate and transport of the injected persulfate solution, and the accompanying treatment of a gasoline the source zone. Copyright © 2013 Elsevier B.V. All rights reserved.

Thermoactivated persulfate oxidation of pesticide chlorpyrifos in aquatic system: kinetic and mechanistic investigations.

Science.gov (United States)

Zhou, Lei; Zhang, Ya; Ying, Rongrong; Wang, Guoqing; Long, Tao; Li, Jianhua; Lin, Yusuo

2017-04-01

The widespread occurrence of organophosphorus pesticides (OPPs) in the environment poses risks to both ecologic system as well as human health. This study investigated the oxidation kinetics of chlorpyrifos (CP), one of the typical OPPs, by thermoactivated persulfate (PS) oxidation process, and evaluated the influence of key kinetic factors, such as PS concentrations, pH, temperature, bicarbonate, and chloride ions. The reaction pathways and mechanisms were also proposed based on products identification by LC-MS techniques. Our results revealed that increasing initial PS concentration and temperature favored the decomposition of CP, whereas the oxidation efficiency was not affected by pH change ranging from 3 to 11. Bicarbonate was found to play a detrimental role on CP removal rates, while chloride showed no effect. The oxidation pathways including initial oxidation of P=S bond to P=O, dechlorination, dealkylation, and the dechlorination-hydroxylation were proposed, and the detailed underlying mechanisms were also discussed. Molecular orbital (MO) calculations indicated that P=S bond was the most favored oxidation site of the molecule. The toxicity of reaction solution was believed to increase due to the formation of products with P=O structures. This work demonstrates that OPPs can readily react with SO 4 ·- and provides important information for further research on the oxidation of these contaminants.

Sulfate radical degradation of acetaminophen by novel iron-copper bimetallic oxidation catalyzed by persulfate: Mechanism and degradation pathways

Science.gov (United States)

Zhang, Yuanchun; Zhang, Qian; Hong, Junming

2017-11-01

A novel iron coupled copper oxidate (Fe2O3@Cu2O) catalyst was synthesized to activate persulfate (PS) for acetaminophen (APAP) degradation. The catalysts were characterized via field-emission scanning electron microscopy and energy-dispersive X-ray spectrometry. The effects of the catalyst, PS concentration, catalyst dosage, initial pH, dissolved oxygen were analyzed for treatment optimization. Results indicated that Fe2O3@Cu2O achieved higher efficiency in APAP degradation than Fe2O3/PS and Cu2O/PS systems. The optimal removal efficiency of APAP (90%) was achieved within 40 min with 0.6 g/L PS and 0.3 g/L catalyst. To clarify the mechanism for APAP degradation, intermediates were analyzed with gas chromatography-mass spectrometry. Three possible degradation pathways were identified. During reaction, Cu(I) was found to react with Fe(III) to generate Fe(II), which is the most active phase for PS activation. Through the use of methanol and tert-butyl alcohol (TBA) as radical trappers, SO4rad - was identified as the main radical species that is generated during oxidation.

Reaction pathway and oxidation mechanisms of dibutyl phthalate by persulfate activated with zero-valent iron

Energy Technology Data Exchange (ETDEWEB)

Li, Huanxuan [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); Wan, Jinquan, E-mail: ppjqwan@scut.edu.cn [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); State Key Lab Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Ma, Yongwen [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China); State Key Lab Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Wang, Yan [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, China, Guangzhou 510640 (China)

2016-08-15

This study investigated reaction pathway and oxidation mechanisms of dibutyl phthalate (DBP) by persulfate (PS) activated with zero-valent iron (ZVI). The DBP degradation was studied at three pH values (acidic, neutral and basic) in the presence of different organic scavengers. Using a chemical probe method, both sulfate radical (SO{sub 4}·{sup −}) and hydroxyl radical (·OH) were found to be primary oxidants at pH 3.0 and pH 7.0, respectively while ·OH was the major specie to oxidize DBP at pH 11.0. A similar result was found in an experiment of Electron Spin Resonance spin-trapping where in addition to ·OH, superoxide radical (O{sub 2}·{sup −}) was detected at pH 11.0. The transformation of degradation products including dimethyl phthalate (DMP), diethyl phthalate (DEP), phthalic anhydride, and acetophenone exhibited diverse variation during the reaction processes. The phthalic anhydride concentration appeared to be maximum at all pHs. Another eleven intermediate products were also found at pH 3.0 by GC–MS and HPLC analysis, and their degradation mechanisms and pathways were proposed. It was suggested that dealkylation, hydroxylation, decarboxylation and hydrogen extraction were the dominant degradation mechanisms of DBP at pH 3.0. - Highlights: • Both SO{sub 4}{sup −}· and ·OH were found to be the major active species at pH 3.0 and pH 7.0. • ·OH and ·O2– were the primary oxidants pH 11.0. • The intermediate products were investigated as well as the degradation pathway. • Dealkylation, hydroxylation, decarboxylation, H-extraction were the major mechanisms.

Fe-based MOFs for efficient adsorption and degradation of acid orange 7 in aqueous solution via persulfate activation

International Nuclear Information System (INIS)

Li, Xianghui; Guo, Weilin; Liu, Zhonghua; Wang, Ruiqin; Liu, Hua

2016-01-01

Graphical abstract: - Highlights: • Fe-based MILs were prepared via the facile solvothermal method. • MILs showed efficient removal rate through adsorption and degradation processes. • A possible catalytic degradation mechanism is proposed. - Abstract: Fe-based metal–organic frameworks (MOFs) including MIL-101(Fe), MIL-100(Fe), MIL-53(Fe), and MIL-88B(Fe) prepared via a facile solvothermal process were introduced as both adsorbents and catalysts to generate powerful radicals from persulfate for acid orange 7 (AO7) removal in aqueous solution. Various catalysts were described and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectra. Because of the high specific surface area of the materials, we studied the adsorption isotherms of the four MILs by the fitting of Langmuir adsorption isotherm. Meanwhile, the catalytic activities in persulfate oxidation system were investigated. The results showed that the sequence of the materials ability in the combination of adsorption and degradation was MIL-101(Fe) > MIL-100(Fe) > MIL-53(Fe) > MIL-88B(Fe), which had a close connection with the activity of metal ion in active site of the catalysts and their different cages in size. Moreover, the reactive species in MILs/persulfate system were identified as sulfate radicals and hydroxyl radicals. The reaction mechanism for persulfate activation over MILs was also studied.

Mechanisms on the Impacts of Alkalinity, pH, and Chloride on Persulfate-Based Groundwater Remediation.

Science.gov (United States)

Li, Wei; Orozco, Ruben; Camargos, Natalia; Liu, Haizhou

2017-04-04

Persulfate (S 2 O 8 2- )-based in situ chemical oxidation (ISCO) has gained more attention in recent years due to the generation of highly reactive and selective sulfate radical (SO 4 •- ). This study examined the effects of important groundwater chemical parameters, i.e., alkalinity, pH, and chloride on benzene degradation via heterogeneous persulfate activation by three Fe(III)- and Mn(IV)-containing aquifer minerals: ferrihydrite, goethite, and pyrolusite. A comprehensive kinetic model was established to elucidate the mechanisms of radical generation and mineral surface complexation. Results showed that an increase of alkalinity up to 10 meq/L decreased the rates of persulfate decomposition and benzene degradation, which was associated with the formation of unreactive surface carbonato complexes. An increase in pH generally accelerated persulfate decomposition due to enhanced formation of reactive surface hydroxo complexation. A change in the chloride level up to 5 mM had a negligibly effect on the reaction kinetics. Kinetics modeling also suggested that SO 4 •- was transformed to hydroxyl radical (HO • ) and carbonate radical (CO 3 •- ) at higher pHs. Furthermore, the yields of two major products of benzene oxidation, i.e., phenol and aldehyde, were positively correlated with the branching ratio of SO 4 •- reacting with benzene, but inversely correlated with that of HO • or CO 3 •- , indicating that SO 4 •- preferentially oxidized benzene via pathways involving fewer hydroxylation steps compared to HO • or CO 3 •- .

A Novel Combination of Surfactant Addition and Persulfate-assisted Electrokinetic Oxidation for Remediation of Pyrene-Contaminated Soil

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M. Abtahi

2018-03-01

Full Text Available Effect of surfactant addition on persulfate-assisted electrokinetic remediation of pyrene-spiked soil was studied. The influence of effective factors including voltage, surfactant addition, moisture content, and persulfate concentration on the removal of initial pyrene concentration of 200 mg kg–1 were investigated. A complete pyrene removal was observed for voltage of 1 V cm–1, saturated conditions, Tween 80 concentration of 20 mL kg–1, and persulfate concentration of 100 mg kg–1 after 24 h, corresponding to pyrene mineralization of 61 %, based on TPH analysis. The experimental results were best fitted with pseudo-first-order kinetic model with correlation coefficient of 0.968 and rate constant of 0.191 min−1. The main intermediates of pyrene degradation were benzene o-toluic acid, acetic, azulene, naphthalene and decanoic acid. Finally, an unwashed hydrocarbon-contaminated soil was subjected to persulfate-assisted electrokinetic remediation, and a TPH removal of 38 % was observed for the initial TPH content of 912 mg kg–1, under the selected conditions.

Degradation of 1,4-dioxane by biochar supported nano magnetite particles activating persulfate.

Science.gov (United States)

Ouyang, Da; Yan, Jingchun; Qian, Linbo; Chen, Yun; Han, Lu; Su, Anqi; Zhang, Wenying; Ni, Hao; Chen, Mengfang

2017-10-01

Nano magnetite biochar composite (nFe 3 O 4 /biochar) was synthesized and used to activate persulfate for the degradation of 1,4-dioxane. Analytical techniques using X-ray diffraction (XRD), fourier transform infrared analysis (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that nFe 3 O 4 was spherical and successfully loaded onto the surface of biochar. The results of batch-scale experiments illustrated that the 1,4-dioxane degradation efficiency in aqueous phase was 98.0% after 120 min reaction with the composite mass ratio of 1:1 between nFe 3 O 4 and the pine needle biochar pyrolyzed at 400 °C (P400) under the initial neutral pH. An electron paramagnetic resonance (EPR) study, free radical quenching experiment and XPS analysis were undertaken to illustrate the mechanism of persulfate activation by nFe 3 O 4 /biochar. Under acidic and neutral conditions, the predominant free radical was SO 4 - whereas OH and SO 4 - predominated when the initial pH was 9.0. The XPS analysis indicated that Fe(II) and oxygenated functional groups activated persulfate. In addition, carbon-carbon double bonds would be transformed into ketone and quinone which could activate persulfate during the reaction. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Efficiency of Ciprofloxacin (CIP Removal from Pharmaceutical Effluents Using the Ozone/Persulfate(O3/PS Process

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Alirezi Rahmani

2016-03-01

Full Text Available A newly emerging environmental problem is the discharge of pharmaceutical effluents containing antibiotic compounds. Compared to common methods, the ozone/persulfate process is a novel measure for treating persistent pollutants. This process is highly efficient in removing pollutants by using the free radicals of sulfates as powerful oxidants. In this study, a semi-continuous reactor with a useful volume of 1 L was used to evaluate the performance of the ozone/persulfate process in treating the ciprofloxacin antibiotic at concentrations from 10 to 100 mg/L in the presence of 0 to 15 mM of persulfate in 30 min. The results showed that under the optimized operating conditions of pH = 3, persulfate dose = 10 mM, ozone dose = 1 g/h, and an initial antibiotic concentration of 10 mg/L, this method was capable of removing 96% of the contaminant. Moreover, the efficiency of the process was found to be a function of experimental conditions. Based on the results of this study, it may be concluded that the ozone/persulfate process can be considered as an appropriate process for treating persistent and non-biodegradable pollutants.

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene.

Science.gov (United States)

Yan, Jingchun; Han, Lu; Gao, Weiguo; Xue, Song; Chen, Mengfang

2015-01-01

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. Copyright © 2014 Elsevier Ltd. All rights reserved.

Field application of a rapid spectrophotometric method for determination of persulfate in soil.

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Colin J Cunningham

Full Text Available Remediation of hydrocarbon contaminated soils can be performed both in situ and ex situ using chemical oxidants such as sodium persulfate. Standard methods for quantifying persulfate require either centrifugation or prolonged settling times. An optimized soil extraction procedure was developed for persulfate involving simple water extraction using a modified disposable syringe. This allows considerable saving of time and removes the need for centrifugation. The extraction time was reduced to only 5 min compared to 15 min for the standard approach. A comparison of the two approaches demonstrated that each provides comparable results. Comparisons were made using high (93 g kg(-1 soil and low (9.3 g kg(-1 soil additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 95±1% and 96±10% were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 86±5% and 117±19% were measured for the lower application rate. Results were obtained in only 25 min and the method is well suited to batch analyses. In addition, it is suitable for application in a small field laboratory or even a mobile, vehicle-based system, as it requires minimal equipment and reagents.

Field Application of a Rapid Spectrophotometric Method for Determination of Persulfate in Soil

Science.gov (United States)

Cunningham, Colin J.; Pitschi, Vanessa; Anderson, Peter; Barry, D. A.; Patterson, Colin; Peshkur, Tanya A.

2013-01-01

Remediation of hydrocarbon contaminated soils can be performed both in situ and ex situ using chemical oxidants such as sodium persulfate. Standard methods for quantifying persulfate require either centrifugation or prolonged settling times. An optimized soil extraction procedure was developed for persulfate involving simple water extraction using a modified disposable syringe. This allows considerable saving of time and removes the need for centrifugation. The extraction time was reduced to only 5 min compared to 15 min for the standard approach. A comparison of the two approaches demonstrated that each provides comparable results. Comparisons were made using high (93 g kg−1 soil) and low (9.3 g kg−1 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 95±1% and 96±10% were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 86±5% and 117±19% were measured for the lower application rate. Results were obtained in only 25 min and the method is well suited to batch analyses. In addition, it is suitable for application in a small field laboratory or even a mobile, vehicle-based system, as it requires minimal equipment and reagents. PMID:23776446

Functionalized Graphene Metal-Free Carbocatalysis of Persulfate and Emerging Contaminant Oxidative Degradation

Science.gov (United States)

Carroll, K. C.; Chen, H.

2016-12-01

We evaluated three types of functionalized, graphene-based materials for activating persulfate (PS) and removing (i.e., sorption and oxidation) sulfamethoxazole (SMX) as a model emerging contaminant. Although advanced oxidative water treatment requires PS activation, activation requires energy or chemical inputs, and toxic substances are contained in many catalysts. Graphene-based materials were examined herein as an alternative to metal-based catalysts. Results show that nitrogen-doped graphene (N-GP) and aminated graphene (NH2-GP) can effectively activate PS. Overall, PS activation by graphene oxide was not observed in this study. N-GP (50 mg L-1) can rapidly activate PS (1 mM) to remove >99.9% SMX within 3 hours, and NH2-GP (50 mg L-1) activated PS (1 mM) can also remove 50% SMX within 10 hours. SMX sorption and total removal was greater for N-GP, which suggests oxidation was enhanced by increasing proximity to PS activation sites. Increasing pH enhanced the N-GP catalytic ability, and >99.9% SMX removal time decreased from 3 hours to 1 hour when pH increased from 3 to 9. However, the PS catalytic ability was inhibited at pH 9 for NH2-GP. Increases in ionic strength (100 mM NaCl or Na2SO4) and addition of radical scavengers (500 mM ethanol) both had negligible impacts on SMX removal. With bicarbonate addition (100 mM), while the catalytic ability of N-GP remained unaltered, NH2-GP catalytic ability was inhibited completely. Humic acid (250 mg L-1) was partially effective in inhibiting SMX removal in both N-GP and NH2-GP systems. These results have implications for elucidating oxidant catalysis mechanisms, and they quantify the ability of functionalization of graphene with hetero-atom doping to effectively catalyze PS for water treatment of organic pollutants including emerging contaminants.

Kinetic and mechanistic investigations of the degradation of sulfamethazine in heat-activated persulfate oxidation process.

Science.gov (United States)

Fan, Yan; Ji, Yuefei; Kong, Deyang; Lu, Junhe; Zhou, Quansuo

2015-12-30

Sulfamethazine (SMZ) is widely used in livestock feeding and aquaculture as an antibiotic agent and growth promoter. Widespread occurrence of SMZ in surface water, groundwater, soil and sediment has been reported. In this study, degradation of SMZ by heat-activated persulfate (PS) oxidation was investigated in aqueous solution. Experimental results demonstrated that SMZ degradation followed pseudo-first-order reaction kinetics. The pseudo-first-order rate constant (kobs) was increased markedly with increasing concentration of PS and temperature. Radical scavenging tests revealed that the predominant oxidizing species was SO4·(-) with HO playing a less important role. Aniline moiety in SMZ molecule was confirmed to be the reactive site for SO4·(-) attack by comparison with substructural analogs. Nontarget natural water constituents affected SMZ removal significantly, e.g., Cl(-) and HCO3(-) improved the degradation while fulvic acid reduced it. Reaction products were enriched by solid phase extraction (SPE) and analyzed by liquid chromatography-electrospray ionization-triple quadrupole mass spectrometry (LC-ESI-MS/MS). 6 products derived from sulfonamide S--N bond cleavage, aniline moiety oxidation and Smiles-type rearrangement were identified, and transformation pathways of SMZ oxidation were proposed. Results reveal that heat-activated PS oxidation could be an efficient approach for remediation of water contaminated by SMZ and related sulfonamides. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance Evaluation of Ozonation Combined with Persulfate Application for Removal of Furfural from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Alireza Rahmani

2017-03-01

Full Text Available Background: Furfural is an organic compound which derived from a variety industrial, including petrochemicals, pulping, pharmaceutical, food. Also is a main agent in many industries and aromatic organic compounds entrance in the environment. There are several methods of treating including physical, chemical, biological and physicochemical for remove this matter. Among advanced oxidation methods can be combined ozonation process with persulfate catalytic are noted. The purpose of this study was to evaluate the efficiency of ozonation process with the use of persulfate in removal furfural from aqueous solution. Materials and Methods: In this study, the efficiency of the process with a concentration furfural 5 to 30 mg/L, concentration persulfate 4 to 15 mM, pH = 3-11 and reaction time of 35 minutes in the semi-continuous reactor with a capacity of one liter was obtained. Results: The results of this study have been shown in  conditions of operation optimal , pH =,3 persulfate dosage 12 mM, ozone dosage of 1 g/min and the initial concentration of furfural  5 mg/L, this process is capable  remove of %93/34 percent Furfural and %70 of the initial COD. Conclusion: The results of this study showed that the ozone/persulfate process can be a suitable process for the removal of organic aromatic compounds including pollutants of interest.

A novel conditioning process for enhancing dewaterability of waste activated sludge by combination of zero-valent iron and persulfate.

Science.gov (United States)

Zhou, Xu; Wang, Qilin; Jiang, Guangming; Liu, Peng; Yuan, Zhiguo

2015-06-01

Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel conditioning method for improving waste activated sludge dewaterability by combination of persulfate and zero-valent iron. The combination of zero-valent iron (0-30g/L) and persulfate (0-6g/L) under neutral pH substantially enhanced the sludge dewaterability due to the advanced oxidization reactions. The highest enhancement of sludge dewaterability was achieved at 4g persulfate/L and 15g zero-valent iron/L, with which the capillary suction time was reduced by over 50%. The release of soluble chemical oxygen demand during the conditioning process implied the decomposition of sludge structure and microorganisms, which facilitated the improvement of dewaterability due to the release of bound water that was included in sludge structure and microorganism. Economic analysis showed that the proposed conditioning process with persulfate and ZVI is more economically favorable for improving WAS dewaterability than classical Fenton reagent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Plutonium oxide dissolution

International Nuclear Information System (INIS)

Gray, J.H.

1992-01-01

Several processing options for dissolving plutonium oxide (PuO 2 ) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO 2 typically generated by burning plutonium metal and PuO 2 produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO 2 in canyon dissolvers. The options involve solid solution formation of PuO 2 With uranium oxide (UO 2 ) and alloying incinerator ash with aluminum. An oxidative dissolution process involving nitric acid solutions containing a strong oxidizing agent, such as cerium (IV), was neither proven nor rejected. This uncertainty was due to difficulty in regenerating cerium (IV) ions during dissolution. However, recent work on silver-catalyzed dissolution of PuO 2 with persulfate has demonstrated that persulfate ions regenerate silver (II). Use of persulfate to regenerate cerium (IV) or bismuth (V) ions during dissolution of PuO 2 materials may warrant further study

Studies on oxidative radiolysis of ibuprofen in presence of potassium persulfate

International Nuclear Information System (INIS)

Paul, Jhimli; Naik, D.B.; Bhardwaj, Y.K.; Varshney, Lalit

2014-01-01

The radiolysis of ibuprofen (IBP), a model pharmaceutical compound, was studied by gamma irradiation in an aqueous solution in the presence and absence of potassium persulfate (K 2 S 2 O 8 ). The extent of mineralization was investigated by measuring the UV–visible spectra, decrease in the chemical oxygen demand (COD) and the total organic carbon (TOC) content of aqueous IBP solution at different doses. The gamma radiolysis, in the presence of K 2 S 2 O 8 , required much lesser dose compared to in the absence of K 2 S 2 O 8 for the same extent of mineralization of aqueous IBP solution. The pulse radiolysis of IBP was carried out under different radiolytic conditions to understand the mechanism of efficient mineralization of IBP during gamma radiolysis in the presence of K 2 S 2 O 8 . It was found that unlike · OH radical, SO 4 ·− radical preferentially produces benzyl type of radicals via the formation of the benzene radical cation. The results concluded that the gamma radiolysis in presence of K 2 S 2 O 8 could be one of the efficient advanced oxidation processes for degradation of pharmaceutical compounds present in the aqueous solution. - Highlights: • The radiolysis of aqueous solution of Ibuprofen (IBP) was investigated. • The COD and TOC content decreased significantly in presence of K 2 S 2 O 8 . • Pulse radiolysis studies revealed the mechanism of mineralization of IBP. • The presence of K 2 S 2 O 8 increased the efficiency of gamma radiolysis

Application of Ammonium Persulfate for Selective Oxidation of Guanines for Nucleic Acid Sequencing

Directory of Open Access Journals (Sweden)

Yafen Wang

2017-07-01

Full Text Available Nucleic acids can be sequenced by a chemical procedure that partially damages the nucleotide positions at their base repetition. Many methods have been reported for the selective recognition of guanine. The accurate identification of guanine in both single and double regions of DNA and RNA remains a challenging task. Herein, we present a new, non-toxic and simple method for the selective recognition of guanine in both DNA and RNA sequences via ammonium persulfate modification. This strategy can be further successfully applied to the detection of 5-methylcytosine by using PCR.

UV Photolysis of Chloramine and Persulfate for 1,4-Dioxane Removal in Reverse-Osmosis Permeate for Potable Water Reuse.

Science.gov (United States)

Li, Wei; Patton, Samuel; Gleason, Jamie M; Mezyk, Stephen P; Ishida, Kenneth P; Liu, Haizhou

2018-06-05

A sequential combination of membrane treatment and UV-based advanced oxidation processes (UV/AOP) has become the industry standard for potable water reuse. Chloramines are used as membrane antifouling agents and therefore carried over into the UV/AOP. In addition, persulfate (S 2 O 8 2- ) is an emerging oxidant that can be added into a UV/AOP, thus creating radicals generated from both chloramines and persulfate for water treatment. This study investigated the simultaneous photolysis of S 2 O 8 2- and monochloramine (NH 2 Cl) on the removal of 1,4-dioxane (1,4-D) for potable-water reuse. The dual oxidant effects of NH 2 Cl and S 2 O 8 2- on 1,4-D degradation were examined at various levels of oxidant dosage, chloride, and solution pH. Results showed that a NH 2 Cl-to-S 2 O 8 2- molar ratio of 0.1 was optimal, beyond which the scavenging by NH 2 Cl of HO • , SO 4 •- , and Cl 2 •- radicals decreased the 1,4-D degradation rate. At the optimal ratio, the degradation rate of 1,4-D increased linearly with the total oxidant dose up to 6 mM. The combined photolysis of NH 2 Cl and S 2 O 8 2- was sensitive to the solution pH due to a disproportionation of NH 2 Cl at pH lower than 6 into less-photoreactive dichloramine (NHCl 2 ) and radical scavenging by NH 4 + . The presence of chloride transformed HO • and SO 4 •- to Cl 2 •- that is less-reactive with 1,4-D, while the presence of dissolved O 2 promoted gaseous nitrogen production. Results from this study suggest that the presence of chloramines can be beneficial to persulfate photolysis in the removal of 1,4-D; however, the treatment efficiency depends on a careful control of an optimal NH 2 Cl dosage and a minimal chloride residue.

Degradation of trimethoprim by gamma irradiation in the presence of persulfate

International Nuclear Information System (INIS)

Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

2016-01-01

The degradation and mineralization of trimethoprim (TMP) by gamma irradiation was investigated in the presence of persulfate (PS). The TMP was degraded at initial concentration of 20 mg/L in aqueous solution with addition of 0, 0.5, 1, 1.5, 2 mM persulfate respectively. The effect of pH values (6.5, 7.5 and 8.5) on TMP degradation was also determined. The experimental results showed that the degradation and mineralization of TMP could be significantly enhanced by persulfate at acidic condition (pH=6.5). Several intermediate products generated during gamma irradiation process through hydroxylation, demethylation and cleavage were identified using liquid chromatography with tandem mass spectrometry (HPLC-MS). The degradation pathway of TMP was tentatively proposed based on the identification of intermediate products. - Highlights: • Trimethoprim (TMP) degradation by gamma irradiation was investigated. • Persulfate significantly enhanced TMP degradation. • The effect of pH values (6.5, 7.5 and 8.5) on TMP degradation was determined. • The possible degradation pathway of TMP was tentatively proposed.

In situ iron activated persulfate oxidative fluid sparging treatment of TCE contamination--a proof of concept study.

Science.gov (United States)

Liang, Chenju; Lee, I-Ling

2008-09-10

In situ chemical oxidation (ISCO) is considered a reliable technology to treat groundwater contaminated with high concentrations of organic contaminants. An ISCO oxidant, persulfate anion (S(2)O(8)(2-)) can be activated by ferrous ion (Fe(2+)) to generate sulfate radicals (E(o)=2.6 V), which are capable of destroying trichloroethylene (TCE). The property of polarity inhibits S(2)O(8)(2-) or sulfate radical (SO(4)(-)) from effectively oxidizing separate phase TCE, a dense non-aqueous phase liquid (DNAPL). Thus the oxidation primarily takes place in the aqueous phase where TCE is dissolved. A bench column study was conducted to demonstrate a conceptual remediation method by flushing either S(2)O(8)(2-) or Fe(2+) through a soil column, where the TCE DNAPL was present, and passing the dissolved mixture through either a Fe(2+) or S(2)O(8)(2-) fluid sparging curtain. Also, the effect of a solubility enhancing chemical, hydroxypropyl-beta-cyclodextrin (HPCD), was tested to evaluate its ability to increase the aqueous TCE concentration. Both flushing arrangements may result in similar TCE degradation efficiencies of 35% to 42% estimated by the ratio of TCE degraded/(TCE degraded+TCE remained in effluent) and degradation byproduct chloride generation rates of 4.9 to 7.6 mg Cl(-) per soil column pore volume. The addition of HPCD did greatly increase the aqueous TCE concentration. However, the TCE degradation efficiency decreased because the TCE degradation was a lower percentage of the relatively greater amount of dissolved TCE by HPCD. This conceptual treatment may serve as a reference for potential on-site application.

Oxidative degradation of atenolol by heat-activated persulfate: Kinetics, degradation pathways and distribution of transformation intermediates.

Science.gov (United States)

Miao, Dong; Peng, Jianbiao; Zhou, Xiaohuan; Qian, Li; Wang, Mengjie; Zhai, Li; Gao, Shixiang

2018-05-17

Atenolol (ATL) has been widely detected in wastewater and aquatic environment. Although satisfactory removal of ATL from wastewater could be achieved, the mineralization ratio is usually low, which may result in the accumulation of its transformation products in the effluent and cause additional ecological risk to the environment. The aim of this study is to explore the effectiveness of heat activated persulfate (PS) in the removal of ATL from wastewater. Influencing factors including temperature, PS dosage, solution pH, existence of NO 3 - , Cl - , HCO 3 - and Suwannee river fulvic acid (SRFA) were examined. Complete removal of ATL was achieved within 40 min at pH 7.0 and 70 °C by using 0.5 mM PS. Inhibitive effects of HCO 3 - and FA had been observed on ATL oxidation, which was increased with the increase of their concentration. Sulfate radical (SO 4 - ) was determined as the main reactive species by quenching experiment. Eight intermediates produced in ATL degradation were identified, and four degradation pathways were proposed based on the analysis of mass spectrum and frontier electron densities. The distribution of major intermediates was influenced by reaction temperature. Hydroxylation intermediates and deamidation intermediate were the most prominent at 50 °C and 60 °C, respectively. All intermediates were completely degraded in 40 min except P134 at 70 °C. Effective removal of TOC (74.12%) was achieved with 0.5 mM PS, pH 7.0 and 70 °C after 240 min. The results proved that heat activation of PS is a promising method to remove organic pollutants in wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison of three persulfate digestion methods for total phosphorus analysis and estimation of suspended sediments

International Nuclear Information System (INIS)

Dayton, Elizabeth Ann; Whitacre, Shane; Holloman, Christopher

2017-01-01

As a result of impairments to fresh surface water quality due to phosphorus enrichment, substantial research effort has been put forth to quantify agricultural runoff phosphorus as related to on-field practices. While the analysis of runoff dissolved phosphorus is well prescribed and leaves little room for variability in methodology, there are several methods and variations of sample preparation reagents as well as analysis procedures for determining runoff total phosphorus. Due to the variation in methodology for determination of total phosphorus and an additional laboratory procedure required to measure suspended solids, the objectives of the current study are to i. compare the performance of three persulfate digestion methods (Acid Persulfate, USGS, and Alkaline Persulfate) for total phosphorus percent recovery across a wide range of suspended sediments (SS), and ii. evaluate the ability of using Al and/or Fe in digestion solution to predict SS as a surrogate to the traditional gravimetric method. Percent recovery of total phosphorus was determined using suspensions prepared from soils collected from 21 agricultural fields in Ohio. The Acid Persulfate method was most effective, with an average total phosphorus percent recovery of 96.6%. The second most effective method was the USGS with an average total phosphorus recovery of 76.1%. However, the Alkaline Persulfate method performed poorly with an average 24.5% total phosphorus recovery. As a result application of Alkaline Persulfate digestion to edge of field monitoring may drastically underestimated runoff total phosphorus. In addition to excellent recovery of total phosphorus, the Acid Persulfate method combined with analysis of Al and Fe by inductively coupled plasma atomic emission spectrometry provides a robust estimate of total SS. Due to the large quantity of samples that can result from water quality monitoring, an indirect measure of total SS could be very valuable when time and budget constraints limit

Removal of Pentachlorophenol Using Microwave Assisted Persulfate from Synthetic Wastewater

Directory of Open Access Journals (Sweden)

Ghorban Asgari

2014-07-01

Full Text Available Pentachlorophenol (PCP is an important class of environmental pollutants which is excessively used in industry in spite of strong evidence about its hazards. Therefore, the removal of PCP from aqua solution is recommended due to its toxicity and health risks. In the present study, the removal of PCP using a modified domestic microwave (MW oven alone and in combination with persulfate (MW/PS was investigated. The effects of operational parameters such as pH of solution, the power of microwave radiations and the amount of persulfate concentration were studied. A spectrophotometer was used for determining of the concentration of pentachlorophenol. The experimental results showed that the removal of PCP was influenced by many factors, such as the pH value, the amount of persulfate and microwave power. The optimum conditions for the best removal rate were obtained at pH=11, a persulfate concentration of 0.02mol/L and microwave irradiation power of about 600W for MW/PS system at constant PCP concentration.  Also, the direct degradation results showed that the removal of PCP was 2% in MW system without PS after 30 min of MW irradiation. The removal of PCP by MW/PS and MW alone were follow first order rate decay kinetics and the rate constants were 0.093 and 0.00066 min-1, respectively.

Degradation of trimethoprim by gamma irradiation in the presence of persulfate

Science.gov (United States)

Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

2016-10-01

The degradation and mineralization of trimethoprim (TMP) by gamma irradiation was investigated in the presence of persulfate (PS). The TMP was degraded at initial concentration of 20 mg/L in aqueous solution with addition of 0, 0.5, 1, 1.5, 2 mM persulfate respectively. The effect of pH values (6.5, 7.5 and 8.5) on TMP degradation was also determined. The experimental results showed that the degradation and mineralization of TMP could be significantly enhanced by persulfate at acidic condition (pH=6.5). Several intermediate products generated during gamma irradiation process through hydroxylation, demethylation and cleavage were identified using liquid chromatography with tandem mass spectrometry (HPLC-MS). The degradation pathway of TMP was tentatively proposed based on the identification of intermediate products.

Test Concept for Advanced Oxidation Techniques

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Mortensen, Lars

advanced on-site oxidation tests. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, hydrogen peroxide, permanganate, and persulfate among others. A versatile construction of the mobile test unit makes it possible to combine different...

Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.

Science.gov (United States)

Yang, Yi; Lu, Xinglin; Jiang, Jin; Ma, Jun; Liu, Guanqi; Cao, Ying; Liu, Weili; Li, Juan; Pang, Suyan; Kong, Xiujuan; Luo, Congwei

2017-07-01

The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H 2 O 2 ) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H 2 O 2 and UV/PDS processes. Because of the electrophilic nature of SO 4 - , the second-order rate constant for the reaction of sulfate radical (SO 4 - ) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO 4 - favored attack on NH 2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H 2 O 2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H 2 O 2 vs. UV/PDS suggested that carbonate radical (CO 3 - ) oxidized SMX through the electron transfer mechanism similar to SO 4 - but with less oxidation capacity. Additionally, SO 4 - and CO 3 - exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using

Activated Persulfate Treatment of 1,4-Dioxane in the Presence of Chlorinated Solvent Co-contaminants

Science.gov (United States)

Boving, T. T.; Eberle, D. E. H.; Ball, R.

2014-12-01

1,4-dioxane is an emerging groundwater contaminant and a likely human carcinogen. Due to its history as a stabilizer in chlorinated solvents, 1,4-dioxane is often found as a co-contaminant at solvent releases sites such as landfills, solvent recycling facilities, vapor decreasing operations, and fire-training areas. Historically, 1,4-dioxane was not routinely analyzed for at solvent release sites. The lack of analyses and the limitations of the analyses that were performed (i.e. high reporting limits) means that the scale of 1,4-dioxane subsurface contamination is still emerging. With the number of known 1,4-dioxane sites increasing, the need for cost effective 1,4-dioxane remediation technologies is rising as well. Remediation strategies that are capable of treating both 1,4-dioxane as well as chlorinated co-contaminants are of particular importance, especially when treating mixed-waste source zones. In the present study, we examined the fate of 1,4-dioxane during the targeted remediation of aqueous phase volatile organic compounds (VOC) using an activated persulfate based ISCO method (OxyZone®). Bench scale laboratory experiments are used to evaluate the treatability of 1,4-dioxane both as a single compound and in the presence of trichloroethene (TCE) and 1,1,1-trichloroethane (1,1,1-TCA). Possible dependencies on oxidant concentration and reaction kinetics were studied. Preliminary results are promising and show that OxyZone® is persistent and long lived, with oxidation of 1,4-dioxane continuing more than 12 days after initial dosage, even at dilute oxidant concentrations. The oxidative destruction of 1,4-dioxane, TCE and 1,1,1-TCA in single compound batch systems followed pseudo first order reaction kinetics. The rate of oxidation for each contaminant increased linearly with increasing persulfate concentration over the range of oxidant concentrations tested. The rate of oxidative destruction, from most easily degraded to least was: TCE > 1,4-Dioxane > 1

Oxidative degradation of tetramethylammonium hydroxide (TMAH) by UV/persulfate and associated acute toxicity assessment.

Science.gov (United States)

Huang, Jingting; Wang, Kai-Sung; Liang, Chenju

2017-07-29

Tetramethylammonium hydroxide (TMAH) is widely used in high-tech industries as a developing agent. Ultraviolet (UV) light-activated persulfate (PS, S 2 O 8 2- ) can be used to generate strongly oxidative sulfate radicals, and it also exhibits the potential to treat TMAH-containing wastewater. This study initially investigated the effect of S 2 O 8 2- concentration and UV strength on the UV/S 2 O 8 2- process for the degradation of TMAH in a batch reactor. The results suggested that 15 watts (W) of UV-activated S 2 O 8 2- at concentrations of 10 or 50 mM resulted in pseudo-first-order TMAH degradation rate constants of 3.1-4.2 × 10 -2 min -1 , which was adopted for determining the hydraulic retention time (HRT) in a continuous stirred tank reactor (CSTR). The operating conditions (15 W UV/10 mM S 2 O 8 2- ) with a HRT of 129 min resulted in stable residual concentrations of S 2 O 8 2- and TMAH at approximately 2.6 mM and 20 mg L -1 in effluent, respectively. Several TMAH degradation intermediates including trimethylamine, dimethylamine, and methylamine were also detected. The effluent was adjusted to a neutral pH and evaluated for its biological acute toxicity using Cyprinus carpio as a bioassay organism. The "bio-acute toxicity unit" (TU a ) was determined to be 1.41, which indicated that the effluent was acceptable for being discharged into an aquatic ecosystem.

Improved Understanding of In Situ Chemical Oxidation. Technical Objective I: Contaminant Oxidation Kinetics Contaminant Oxidation Kinetics

Science.gov (United States)

2009-05-01

methyl tert butyl ether NAPL non-aqueous phase liquid NOD natural oxidant demand •OH hydroxide radical Ox oxidant O3 ozone PCE...and persulfate; and Technical Objective 2, assess how soil properties (e.g., soil mineralogy , natural carbon content) affect oxidant mobility and...to develop a general description of kobs vs. T because there are many reactions that can contribute to the concentration of the reactive intermediate

Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

Energy Technology Data Exchange (ETDEWEB)

Cassidy, Daniel P., E-mail: daniel.cassidy@wmich.edu [Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008 (United States); Srivastava, Vipul J., E-mail: vipul.srivastava@ch2m.com [CH2M HILL, 125S Wacker, Ste 3000, Chicago, IL 60606 (United States); Dombrowski, Frank J., E-mail: frank.dombrowski@we-energies.com [We Energies, 333W Everett St., A231, Milwaukee, WI 53203 (United States); Lingle, James W., E-mail: jlingle@epri.com [Electric Power Research Institute (EPRI), 4927W Willow Road, Brown Deer, WI 53223 (United States)

2015-10-30

Highlights: • Portland cement and lime activated persulfate by increasing pH and temperature. • Chemical oxidation achieved BTEX and PAH removal ranging from 55% to 75%. • Activating persulfate with ISS amendments reduced leachability more than NaOH. • Native sulfate-reducing bacteria degraded PAHs within weeks after ISCO finished. • ISCO, ISS, and anaerobic bioremediation were combined in a single application. - Abstract: Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks.

Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

International Nuclear Information System (INIS)

Cassidy, Daniel P.; Srivastava, Vipul J.; Dombrowski, Frank J.; Lingle, James W.

2015-01-01

Highlights: • Portland cement and lime activated persulfate by increasing pH and temperature. • Chemical oxidation achieved BTEX and PAH removal ranging from 55% to 75%. • Activating persulfate with ISS amendments reduced leachability more than NaOH. • Native sulfate-reducing bacteria degraded PAHs within weeks after ISCO finished. • ISCO, ISS, and anaerobic bioremediation were combined in a single application. - Abstract: Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks

Geochemical and Microbiological Characteristics during in Situ Chemical Oxidation and in Situ Bioremediation at a Diesel Contaminated Site

NARCIS (Netherlands)

Sutton, N.B.; Kalisz, M.; Krupanek, J.; Marek, J.; Grotenhuis, J.T.C.; Smidt, H.; Weert, de J.; Rijnaarts, H.H.M.; Gaans, van P.; Keijzer, T.

2014-01-01

While in situ chemical oxidation with persulfate has seen wide commercial application, investigations into the impacts on groundwater characteristics, microbial communities and soil structure are limited. To better understand the interactions of persulfate with the subsurface and to determine the

Promoted degradation of perfluorooctanic acid by persulfate when adding activated carbon

Energy Technology Data Exchange (ETDEWEB)

Lee, Yu-Chi [Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Rd., Taipei 106, Taiwan, ROC (China); Lo, Shang-Lien, E-mail: sllo@ntuedu.tw [Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Rd., Taipei 106, Taiwan, ROC (China); Kuo, Jeff [Department of Civil and Environmental Engineering, California State University, 800 North, State College Blvd., Fullerton (United States); Huang, Chin-Pao [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States)

2013-10-15

Highlights: • PFOA removal and defluorination with AC/PS are 12 and 19 times higher than PS only • AC can activate PS to accelerate the decomposition and mineralization of PFOA. • With AC/PS, a lower reaction temperature and a shorter reaction time would suffice • A 2-cycle schematic reaction mechanism was proposed to describe PS oxidation of PFOA. -- Abstract: Treatment of persistent perfluorooctanoic acid (PFOA) in water using persulfate (PS) oxidation typically requires an elevated temperature or UV irradiation, which is energy-consuming. Under relatively low temperatures of 25–45 °C, activated carbon (AC) activated PS oxidation of PFOA was evaluated for its potential of practical applications. With presence of AC in PS oxidation, PFOA removal efficiency at 25 °C reached 682% with a high defluorination efficiency of 549% after 12 h and few intermediates of short-chain perfluorinated carboxylic acids (PFCAs) were found. The removal and defluorination rates with the combined AC/PS system were approximately 12 and 19 times higher than those of the PS-only system, respectively. Activated carbon not only removes PFOA through adsorption, but also activates PS to form sulfate radicals that accelerate the decomposition and mineralization of PFOA. The activation energy for PS oxidation of PFOA was reduced from 668 to 261 kJ/mol by the catalytic effect of AC, which implies a lower reaction temperature and a shorter reaction time would suffice. A 2-cycle schematic reaction mechanism was used to describe PS oxidation of PFOA with the generation of various intermediates and end-products.

Promoted degradation of perfluorooctanic acid by persulfate when adding activated carbon

International Nuclear Information System (INIS)

Lee, Yu-Chi; Lo, Shang-Lien; Kuo, Jeff; Huang, Chin-Pao

2013-01-01

Highlights: • PFOA removal and defluorination with AC/PS are 12 and 19 times higher than PS only • AC can activate PS to accelerate the decomposition and mineralization of PFOA. • With AC/PS, a lower reaction temperature and a shorter reaction time would suffice • A 2-cycle schematic reaction mechanism was proposed to describe PS oxidation of PFOA. -- Abstract: Treatment of persistent perfluorooctanoic acid (PFOA) in water using persulfate (PS) oxidation typically requires an elevated temperature or UV irradiation, which is energy-consuming. Under relatively low temperatures of 25–45 °C, activated carbon (AC) activated PS oxidation of PFOA was evaluated for its potential of practical applications. With presence of AC in PS oxidation, PFOA removal efficiency at 25 °C reached 682% with a high defluorination efficiency of 549% after 12 h and few intermediates of short-chain perfluorinated carboxylic acids (PFCAs) were found. The removal and defluorination rates with the combined AC/PS system were approximately 12 and 19 times higher than those of the PS-only system, respectively. Activated carbon not only removes PFOA through adsorption, but also activates PS to form sulfate radicals that accelerate the decomposition and mineralization of PFOA. The activation energy for PS oxidation of PFOA was reduced from 668 to 261 kJ/mol by the catalytic effect of AC, which implies a lower reaction temperature and a shorter reaction time would suffice. A 2-cycle schematic reaction mechanism was used to describe PS oxidation of PFOA with the generation of various intermediates and end-products

Comparison of the effectiveness of soil heating prior or during in situ chemical oxidation (ISCO) of aged PAH-contaminated soils.

Science.gov (United States)

Ranc, Bérénice; Faure, Pierre; Croze, Véronique; Lorgeoux, Catherine; Simonnot, Marie-Odile

2017-04-01

Thermal treatments prior or during chemical oxidation of aged polycyclic aromatic hydrocarbon (PAH)-contaminated soils have already shown their ability to increase oxidation effectiveness. However, they were never compared on the same soil. Furthermore, oxygenated polycyclic aromatic hydrocarbons (O-PACs), by-products of PAH oxidation which may be more toxic and mobile than the parent PAHs, were very little monitored. In this study, two aged PAH-contaminated soils were heated prior (60 or 90 °C under Ar for 1 week) or during oxidation (60 °C for 1 week) with permanganate and persulfate, and 11 O-PACs were monitored in addition to the 16 US Environmental Protection Agency (US EPA) PAHs. Oxidant doses were based on the stoichiometric oxidant demand of the extractable organic fraction of soils by using organic solvents, which is more representative of the actual contamination than only the 16 US EPA PAHs. Higher temperatures actually resulted in more pollutant degradation. Two treatments were about three times more effective than the others: soil heating to 60 °C during persulfate oxidation and soil preheating to 90 °C followed by permanganate oxidation. The results of this study showed that persulfate effectiveness was largely due to its thermal activation, whereas permanganate was more sensitive to PAH availability than persulfate. The technical feasibility of these two treatments will soon be field-tested in the unsaturated zone of one of the studied aged PAH-contaminated soils.

Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil.

Science.gov (United States)

Cassidy, Daniel P; Srivastava, Vipul J; Dombrowski, Frank J; Lingle, James W

2015-10-30

Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. Copyright © 2015 Elsevier B.V. All rights reserved.

Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions

Energy Technology Data Exchange (ETDEWEB)

Liu, Yunde [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Zhou, Aiguo, E-mail: aiguozhou@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gan, Yiqun; Li, Xiaoqian [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)

2016-04-01

Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO{sub 4}·{sup −}). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe{sup 0} activated persulfate. • The enrichment factors was independent of Fe{sup 0}, SO{sub 4}{sup 2−}, or HCO{sub 3}{sup −} concentration. • Cl{sup −} significantly influenced the carbon isotope fractionation.

Variability in carbon isotope fractionation of trichloroethene during degradation by persulfate activated with zero-valent iron: Effects of inorganic anions

International Nuclear Information System (INIS)

Liu, Yunde; Zhou, Aiguo; Gan, Yiqun; Li, Xiaoqian

2016-01-01

Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO_4·"−). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe"0 activated persulfate. • The enrichment factors was independent of Fe"0, SO_4"2"−, or HCO_3"− concentration. • Cl"− significantly influenced the carbon isotope fractionation.

Simultaneous catalytic degradation of 2,4-D and MCPA herbicides using sulfate radical-based heterogeneous oxidation over persulfate activated by natural hematite (α-Fe2O3/PS)

Science.gov (United States)

Kermani, Majid; Mohammadi, Farzad; Kakavandi, Babak; Esrafili, Ali; Rostamifasih, Zeinab

2018-06-01

Herein, a sulfate radical (SO4rad -)-based oxidation process was utilized for simultaneous degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicides using mesoporous hematite-based natural semi-conductor minerals (HM-NSMs) as efficient activators of persulfate (PS). The features of the catalyst were characterized using field emission scanning electron microscopy (FESEM); Brunauer, Emmett and Teller (BET) analysis; X-ray diffraction (XRD); and energy-dispersive X-ray spectroscopy (EDS). The effect of some operational parameters, including solution pH, catalyst loading, PS dosage and temperature, on the performance system of PS/HM-NSMs was examined. A plausible oxidation mechanism for degradation of both pollutants was also proposed. Increasing the removal efficiency of herbicides follows the order of PS/HM-NSM > HM-NSM > PS. In all experiments, the 2,4-D removal rates were slightly lower than those for MCPA, indicating that 2,4-D has a more recalcitrant nature than MCPA. Under optimized conditions, degradation rates of 68.1% and 74.5% were achieved for 2,4-D and MCPA, respectively, during a 120-min reaction. HM-NSM displays a highly synergistic effect on the degradation of herbicides in the presence of PS. The trapping experiments demonstrated that both OHrad and SO4rad - radicals contribute significantly during the degradation of 2,4-D and MCPA and that sulfate radicals were the dominant species. A mineralization degree of 36% was obtained under optimum conditions. In conclusion, the coupling of PS and HM-NSM is a promising and effective technique to degrade organic matter for the treatment of herbicide-contaminated waters and wastewaters under real conditions.

76 FR 35402 - Persulfates From the People's Republic of China: Notice of Correction to the Final Results of the...

Science.gov (United States)

2011-06-17

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-847] Persulfates From the People.... Department of Commerce, 14th Street and Constitution Avenue, NW., Washington, DC 20230; telephone: (202) 482... antidumping duty order on persulfates from the People's Republic of China (``PRC'').\\1\\ The period of review...

A soft chemical route to multicomponent lithium transition metal oxide nanowires as promising cathode materials for lithium secondary batteries

International Nuclear Information System (INIS)

Park, Dae-Hoon; Lim, Seung-Tae; Hwang, Seong-Ju

2006-01-01

We have synthesized 1D nanowires of lithium nickel manganese oxides with two different crystal structures through the chemical oxidation reaction of solid-state precursor LiMn 0.5 Ni 0.5 O 2 under hydrothermal condition. According to X-ray diffraction and elemental analyses, the nanowires obtained by persulfate treatments at 65 and 120 deg. C crystallize with a hexagonal layered and an α-MnO 2 -type structure, respectively, in which nickel and manganese ions exist in octahedral sites. Electron microscopic analyses reveal that the platelike crystallites of the precursor are changed into nanowires with the diameter of ∼20 nm after the persulfate treatment. Thermal and infrared spectroscopic analyses clearly demonstrate that, in comparison with α-MnO 2 -structured nanowires, the hexagonal layered nanowires contain less water molecules in the lattice, which makes them suitable for the application as electrode materials for lithium secondary batteries. According to electrochemical measurements, the hexagonal layered nanowires show a larger discharge capacity and an excellent cyclability with respect to repeated Li intercalation-disintercalation process. X-ray diffraction and electron microscopic analyses on the samples subjected to electrochemical analysis reveal that the layered structure and 1D morphology of the nanowires are still maintained after the electrochemical cyclings, which is responsible for their excellent electrochemical performances

Comparative study of the formation of brominated disinfection byproducts in UV/persulfate and UV/H2O2 oxidation processes in the presence of bromide.

Science.gov (United States)

Wang, Lu; Ji, Yuefei; Lu, Junhe; Kong, Deyang; Yin, Xiaoming; Zhou, Quansuo

2017-10-01

The objective of this research was to compare the transformation of Br - and formation of brominated byproducts in UV/persulfate (PS) and UV/H 2 O 2 processes. It was revealed that Br - was efficiently transformed to free bromine which reacted with humic acid (HA) or dihydroxybenzoic acid resulting in the formation of brominated byproducts such as bromoacetic acids (BAAs) in UV/PS system. In contrast, no free bromine and brominated byproducts could be detected in UV/H 2 O 2 system, although the oxidization of Br - was evident. We presumed that the oxidation of Br - by hydroxyl radicals led to the formation of bromine radicals. However, the bromine radical species could be immediately reduced back to Br - by H 2 O 2 before coupling to each other to form free bromine, which explains the undetection of free bromine and BAAs in UV/H 2 O 2 . In addition to free bromine, we found that the phenolic functionalities in HA molecules, which served as the principal reactive sites for free chlorine attack, could be in situ generated when HA was exposed to free radicals. This study demonstrates that UV/H 2 O 2 is more suitable than UV/PS for the treatment of environmental matrices containing Br - . Graphical abstract Graphical abstract.

[Degradation of Acid Orange 7 with Persulfate Activated by Silver Loaded Granular Activated Carbon].

Science.gov (United States)

Wang, Zhong-ming; Huang, Tian-yin; Chen, Jia-bin; Li, Wen-wei; Zhang, Li-ming

2015-11-01

Granular activated carbon with silver loaded as activator (Ag/GAC) was prepared using impregnation method. N2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize the Ag/GAC, showing that silver was successfully loaded on granular activated carbon. The oxidation degradation of acid orange 7 (AO7) by the Ag/GAC activated by persulfate (PS) was investigated at ambient temperature. The influences of factors such as Ag loading, PS or Ag/GAC dosages and initial pH on the degradation of AO7 were evaluated. The results demonstrated that the degradation rate of AO7 could reach more than 95.0% after 180 min when the Ag loading content, PS/AO7 molar ratio, the Ag/GAC dosage were 12.7 mg x g(-1), 120: 1, 1.0 g x L(-1), respectively. The initial pH had significant effect on the AO7 degradation, with pH 5.0 as the optimal pH for the degradation of AO7. The possible degradation pathway was proposed for the AO7 degradation by using UV-visible spectroscopy and gas chromatography-mass spectrometry (GG/MS). The azo bond and naphthalene ring in the AO7 were destroyed during the degradation, with phthalic acid and acetophenone as the main degradation products.

A study on microwave oxidation of landfill leachate—Contributions of microwave-specific effects

International Nuclear Information System (INIS)

Chou, Yu-Chieh; Lo, Shang-Lien; Kuo, Jeff; Yeh, Chih-Jung

2013-01-01

Highlights: ► pH has an insignificant effect on TOC removals and 550 W has a well performance. ► MOP has well removals of color, UV 254 , and TOC at 550 W/85 °C. ► TOC removals were higher at higher microwave setting (550 W vs. 128 W). ► The microwave-specific effects on TOC removal were usually synergistic in MOP. ► COD analyses showed persulfate decayed rapidly in either MOP or CHO treatment. -- Abstract: Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. The experimental parameters include pH, temperature, oxidant doses, microwave power setting, and irradiation time. The study explored the microwave-specific effects of the MOP. The contributions of pure thermal, persulfate oxidation and microwave irradiation on TOC removal were quantified. It was then found the combinations of them were usually synergistic in MOP except two of them were antagonistic (128 W/85 °C/1 M Na 2 S 2 O 8 and 128 W/85 °C/2 M Na 2 S 2 O 8 ). At the highest temperature tested (85 °C) in this study, microwave irradiation may cause generation and termination of oxidizing radicals at adverse rates. The study also found that persulfate decayed rapidly in either MOP or conventional heating oxidation (CHO) treatment of landfill leachate

Geochemical and microbiological characteristics during in situ chemical oxidation and in situ bioremediation at a diesel contaminated site.

Science.gov (United States)

Sutton, Nora B; Kalisz, Mariusz; Krupanek, Janusz; Marek, Jan; Grotenhuis, Tim; Smidt, Hauke; de Weert, Jasperien; Rijnaarts, Huub H M; van Gaans, Pauline; Keijzer, Thomas

2014-02-18

While in situ chemical oxidation with persulfate has seen wide commercial application, investigations into the impacts on groundwater characteristics, microbial communities and soil structure are limited. To better understand the interactions of persulfate with the subsurface and to determine the compatibility with further bioremediation, a pilot scale treatment at a diesel-contaminated location was performed consisting of two persulfate injection events followed by a single nutrient amendment. Groundwater parameters measured throughout the 225 day experiment showed a significant decrease in pH and an increase in dissolved diesel and organic carbon within the treatment area. Molecular analysis of the microbial community size (16S rRNA gene) and alkane degradation capacity (alkB gene) by qPCR indicated a significant, yet temporary impact; while gene copy numbers initially decreased 1-2 orders of magnitude, they returned to baseline levels within 3 months of the first injection for both targets. Analysis of soil samples with sequential extraction showed irreversible oxidation of metal sulfides, thereby changing subsurface mineralogy and potentially mobilizing Fe, Cu, Pb, and Zn. Together, these results give insight into persulfate application in terms of risks and effective coupling with bioremediation.

Determination of an Effective Perfluorinated Compounds (PFCs) Oxidation Method

Science.gov (United States)

Siriwardena, D. P.; Crimi, M.; Holsen, T.; Bellona, C.

2014-12-01

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a stable synthetic class of chemicals ubiquitously spread in environmental media (i.e. air, soil, biota, surface water and groundwater). The substances' strong polar carbon-fluorine bonds and their high thermal and chemical stability make them resistant to biological, chemical, and physical degradation. The purpose of this research is to identify the most effective oxidation method to treat perfluorinated compounds (PFCs) and their by-products that is suitable for in situ application. The laboratory oxidation study focuses on the more commonly detected and studied long-chain (C-8) PFAS; perfluorooctanoic acids (PFOA) and perfluorooctane sulfonic acid (PFOS). Existing research evaluating oxidizing treatment effectiveness on perfluoroalkyl sulfoinoic acids (PFSAs) is limited. A review of the literature and results from preliminary studies indicate that activated persulfate and catalyzed hydrogen peroxide propagation (CHP) reactions appear to be promising oxidants for PFOA. It has been demonstrated that the reactivity of superoxide in water increases in the presence of hydrogen peroxide (H2O2) and solids. Superoxide generated in CHP reactions degrades PFOA seemingly similar to superoxide-mediated destruction of the perhalogenated compounds.The goal of this study is to look at conditions that promote generation of superoxide and look at PFASs treatment effectiveness and byproduct generation. CHP reactions are conducted with varying amount of H2O2 and Fe(III) to determine the optimum conditions for PFC degradation. Results will be compared to those of another experiment using manganese dioxide as a CHP catalyst with varied H2O2 concentration to generate superoxide to degrade PFASs. Activated persulfate conditions to be compared include alkaline pH activation, heat activation, and dual oxidation (combined H2O2 and persulfate ). This presentation will focus on a comparison of oxidation effectiveness under the

Electron uptake by iron-oxidizing phototrophic bacteria

Energy Technology Data Exchange (ETDEWEB)

Bose, A; Gardel, EJ; Vidoudez, C; Parra, EA; Girguis, PR

2014-02-26

Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.

Facile synthesis of ammonium vanadate nanofibers by using reflux in aqueous V{sub 2}O{sub 5} solution with ammonium persulfate

Energy Technology Data Exchange (ETDEWEB)

Lee, Se Hun [Department of Convergence Nanoscience, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Koo, Jun Mo [Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Oh, Seong Geun, E-mail: seongoh@hanyang.ac.kr [Department of Chemical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Im, Seung Soon, E-mail: imss007@hanyang.ac.kr [Department of Convergence Nanoscience, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Department of Organic and Nano Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2017-06-15

Ammonium vanadate nanofibers were synthesized by simple reflux method in aqueous V{sub 2}O{sub 5} solution with ammonium persulfate without relying on surfactants, catalysts, harmful solvents and autoclave. The degree of intercalation by cationic ammonium ions into the crystal structure of vanadium oxide along with its change in chemical composition were analyzed by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR). The morphological changes toward nanofiber structure, having diameter of 20–30 nm and a few μm length, were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influences of synthetic conditions, such as reaction time and concentration of sulfate (SO{sub 4}{sup 2-}), on the crystal structures and morphologies of the resulting products have investigated. As a result, the ammonium vanadate nanofiber was formed in a short reaction time through a simple reflux method and yielded comparable electrical conductivity 1.47 × 10{sup -2} S/cm. - Highlights: • Ammonium vanadate nanofiber (AVFr) was prepared by simple reflux method. • AVFr yielded comparable electrical conductivity 1.47 × 10{sup -2} S/cm. • The electrical conductivity was improved by the increased amount of ammonium ion. • Sulfate ions (SO{sub 4}{sup 2-}) play a crucial role in controlling the morphology of nanofiber.

Adaptive oxide electronics: A review

Science.gov (United States)

Ha, Sieu D.; Ramanathan, Shriram

2011-10-01

Novel information processing techniques are being actively explored to overcome fundamental limitations associated with CMOS scaling. A new paradigm of adaptive electronic devices is emerging that may reshape the frontiers of electronics and enable new modalities. Creating systems that can learn and adapt to various inputs has generally been a complex algorithm problem in information science, albeit with wide-ranging and powerful applications from medical diagnosis to control systems. Recent work in oxide electronics suggests that it may be plausible to implement such systems at the device level, thereby drastically increasing computational density and power efficiency and expanding the potential for electronics beyond Boolean computation. Intriguing possibilities of adaptive electronics include fabrication of devices that mimic human brain functionality: the strengthening and weakening of synapses emulated by electrically, magnetically, thermally, or optically tunable properties of materials.In this review, we detail materials and device physics studies on functional metal oxides that may be utilized for adaptive electronics. It has been shown that properties, such as resistivity, polarization, and magnetization, of many oxides can be modified electrically in a non-volatile manner, suggesting that these materials respond to electrical stimulus similarly as a neural synapse. We discuss what device characteristics will likely be relevant for integration into adaptive platforms and then survey a variety of oxides with respect to these properties, such as, but not limited to, TaOx, SrTiO3, and Bi4-xLaxTi3O12. The physical mechanisms in each case are detailed and analyzed within the framework of adaptive electronics. We then review theoretically formulated and current experimentally realized adaptive devices with functional oxides, such as self-programmable logic and neuromorphic circuits. Finally, we speculate on what advances in materials physics and engineering may

Spectroscopic and electrical sensing mechanism in oxidant-mediated polypyrrole nanofibers/nanoparticles for ammonia gas

International Nuclear Information System (INIS)

Ishpal; Kaur, Amarjeet

2013-01-01

Ammonia gas sensing mechanism in oxidant-mediated polypyrrole (PPy) nanofibers/nanoparticles has been studied through spectroscopic and electrical investigations. PPy nanofibers/nanoparticles have been synthesized by chemical oxidation method in the presence of various oxidizing agents such as ammonium persulfate (APS), potassium persulfate (PPS), vanadium pentoxide (V 2 O 5 ), and iron chloride (FeCl 3 ). Scanning electron microscopy study revealed that PPy nanofibers of about 63, 71 and 79 nm diameters were formed in the presence of APS, PPS, V 2 O 5 , respectively, while PPy nanoparticles of about 100–110 nm size were obtained in the presence of FeCl 3 as an oxidant. The structural investigations and confirmation of synthesis of PPy were established through Fourier transform infrared and Raman spectroscopy. The gas sensing behavior of the prepared PPy samples is investigated by measuring the electrical resistance in ammonia environment. The observed gas sensing response (ΔR/Rx100) at 100 ppm level of ammonia is ∼4.5 and 18 % for the samples prepared with oxidizing agents FeCl 3 and APS, respectively, and by changing the ammonia level from 50 to 300 ppm, the sensing response varies from ∼4.5 to 11 % and ∼10 to 39 %, respectively. Out of all four samples, the PPy nanofibers prepared in the presence of APS have shown the best sensing response. The mechanism of gas sensing response of the PPy samples has been investigated through Raman spectroscopy study. The decrease of charge carrier concentration through reduction of polymeric chains has been recognized through Raman spectroscopic measurements recorded in ammonia environment.

Leaching of a copper flotation concentrate with ammonium persulfate in an autoclave system

Science.gov (United States)

Deniz Turan, M.; Soner Altundoğan, H.

2014-09-01

The leaching behavior of a copper flotation concentrate was investigated using ammonium persulfate (APS) in an autoclave system. The decomposition products of APS, active oxygen, and acidic medium were used to extract metals from the concentrate. Leaching experiments were performed to compare the availability of APS as an oxidizing agent for leaching of the concentrate under atmospheric conditions and in an autoclave system. Leaching temperature and APS concentration were found to be important parameters in both leaching systems. Atmospheric leaching studies showed that the metal extractions increased with the increase in APS concentration and temperature (up to 333 K). A similar tendency was determined in the autoclave studies up to 423 K. It was also determined that the metal extractions decreased at temperatures above 423 K due to the passivation of the particle surface by molten elemental sulfur. The results showed that higher copper extractions could be achieved using an autoclave system.

Facile synthesis of poly (p-phenylenediamine)/MWCNT ...

Indian Academy of Sciences (India)

Poly(-phenylenediamine) (PPD)/carboxylic acid-functionalized multiwalled carbon nanotubes (-MWCNTs) nanocomposites were prepared by chemical oxidative polymerization using potassium persulfate (K2S2O8) as an oxidant. Field-emission scanning electron microscopy (FE–SEM) and field-emission transmission ...

The 2016 oxide electronic materials and oxide interfaces roadmap

DEFF Research Database (Denmark)

Lorenz, M.; Rao, M. S. Ramachandra; Venkatesan, T.

2016-01-01

of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap......, Pentcheva, and Gegenwart. Finally, Miletto Granozio presents the European action ‘towards oxide-based electronics’ which develops an oxide electronics roadmap with emphasis on future nonvolatile memories and the required technologies.In summary, we do hope that this oxide roadmap appears as an interesting...

Recovery of microbial diversity and activity during bioremediation following chemical oxidation of diesel contaminated soils

NARCIS (Netherlands)

Sutton, N.B.; Langenhoff, A.A.M.; Hidalgo Lasso, D.; Zaan, van der B.M.; Gaans, van P.; Maphosa, F.; Smidt, H.; Grotenhuis, J.T.C.; Rijnaarts, H.H.M.

2014-01-01

To improve the coupling of in situ chemical oxidation and in situ bioremediation, a systematic analysis was performed of the effect of chemical oxidation with Fenton's reagent, modified Fenton's reagent, permanganate, or persulfate, on microbial diversity and activity during 8 weeks of incubation in

Seeded emulsion polymerization of butadiene. 2. Effects of persulfate and tert-dodecyl mercaptan

NARCIS (Netherlands)

Verdurmen, E.M.F.J.; Geurts, J.M.; Verstegen, J.M.; Maxwell, I.A.; German, A.L.

1993-01-01

The kinetics of the emulsion polymn. of butadiene at 60 Deg in Smith-Ewart interval III were investigated using sodium persulfate as initiator. Monomer conversion was based on gravimetrically calibrated online densitometry. Plots of the product of the propagation rate coeff., Kp, and the av. no. of

Optical properties and electronic transitions of zinc oxide, ferric oxide, cerium oxide, and samarium oxide in the ultraviolet and extreme ultraviolet

DEFF Research Database (Denmark)

Pauly, N; Yubero, F; Espinós, J P

2017-01-01

Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3-2.0 ke...

Transparent Oxide Semiconductors for Emerging Electronics

KAUST Repository

Caraveo-Frescas, Jesus Alfonso

2013-01-01

Transparent oxide electronics have emerged as promising materials to shape the future of electronics. While several n-type oxides have been already studied and demonstrated feasibility to be used as active materials in thin film transistors, high

Synthesis of thermoplastic elastomer using potassium persulfate and ammonium peroxydisulfate initiator

International Nuclear Information System (INIS)

Dewi Sondari; Agus Haryono; M Ghozali; Ahmad Randy; Kuntari Adi Suhardjo; Ariyadi B; Surasno

2010-01-01

Thermoplastic elastomer is polymeric material that has elastomer and thermoplastic properties. This material can be easily molded into finished and recyclable goods, thus environmentally safe for long term application. In this study we synthesize thermoplastic elastomer using two initiator that are potassium persulfate and ammonium peroxydisulfate with natural rubber to monomer (styrene/methyl methacrylate) ratio of 50 : 50 and 60 : 40 (v/v). The process of thermoplastic elastomer synthesis was conducted with emulsion grafting polymerization method for 6 hours at 65 °C. We used sodium dodecyl sulfate as emulsifier. FT-IR analysis result shows that grafting process had already occurred shown by new peaks that were observed in 1743 and 1519 cm"-"1. These peaks was assigned to carbonyl (C=O) group of methyl methacrylate and C=C benzene of styrene respectively. From "1H-NMR new peaks at δ = 7.1 ppm was aromatic proton from phenyl group of styrene, at δ = 3.5 ppm was methoxy proton of grafted methyl methacrylate acrylic group, and at δ = 5.1 ppm that is resonance of isoprene methine proton. This result showed that methyl methacrylate and styrene had already grafted onto natural rubber backbone. Initiator influenced grafting efficiency. Potassium persulfate gave 97.6 % grafting efficiency while ammonium peroxydisulfate gave 90.2 % grafting efficiency. (author)

Electron donating and acid-base properties of cerium oxide and its mixed oxides with alumina

International Nuclear Information System (INIS)

Sugunan, S.; Jalaja, J.M.

1994-01-01

The electron donating properties of cerium oxide activated at 300, 500 and 800 degC and of its mixed oxides with alumina were examined based on the adsorption of electron acceptors exhibiting different electron affinities. The surface acidity/basicity of the oxides was determined by titrimetry; the H 0,max values are given. The limit of electron transfer from the oxide surface lies within the region of 1.77 and 2.40 eV in terms of the electron affinity of the electron acceptor. Cerium oxide promotes the electron donor nature of alumina while leaving the limit of electron transfer unchanged. 2 tabs., 4 figs., 13 refs

Effects of interfacial Fe electronic structures on magnetic and electronic transport properties in oxide/NiFe/oxide heterostructures

International Nuclear Information System (INIS)

Liu, Qianqian; Chen, Xi; Zhang, Jing-Yan; Yang, Meiyin; Li, Xu-Jing; Jiang, Shao-Long; Liu, Yi-Wei; Cao, Yi; Wu, Zheng-Long; Feng, Chun; Ding, Lei; Yu, Guang-Hua

2015-01-01

Highlights: • The magnetic and transport properties of oxide/NiFe/oxide films were studied. • The oxide (SiO 2 , MgO and HfO 2 ) has different elemental electronegativity. • Redox reaction at different NiFe/oxide interface is dependent on the oxide layer. • Different interfacial electronic structures shown by XPS influence the properties. - Abstract: We report that the magnetic and electronic transport properties in oxide/NiFe(2 nm)/oxide film (oxide = SiO 2 , MgO or HfO 2 ) are strongly influenced by the electronic structure of NiFe/oxide interface. Magnetic measurements show that there exist magnetic dead layers in the SiO 2 sandwiched film and MgO sandwiched film, whereas there is no magnetic dead layer in the HfO 2 sandwiched film. Furthermore, in the ultrathin SiO 2 sandwiched film no magnetoresistance (MR) is detected, while in the ultrathin MgO sandwiched film and HfO 2 sandwiched film the MR ratios reach 0.35% and 0.88%, respectively. The investigation by X-ray photoelectron spectroscopy reveals that the distinct interfacial redox reactions, which are dependent on the oxide layers, lead to the variation of magnetic and transport properties in different oxide/NiFe/oxide heterostructures

Electron trapping during irradiation in reoxidized nitrided oxide

International Nuclear Information System (INIS)

Mallik, A.; Vasi, J.; Chandorkar, A.N.

1993-01-01

Isochronal detrapping experiments have been performed following irradiation under different gate biases in reoxidized nitrided oxide (RNO) MOS capacitors. These show electron trapping by the nitridation-induced electron traps at low oxide fields during irradiation. A difference in the detrapping behavior of trapped holes and electrons is observed, with trapped holes being detrapped at relatively lower temperatures compared to trapped electrons. Electron trapping shows a strong dependence on tile magnitude of the applied gate bias during irradiation but is independent of its polarity. Conventional oxide devices, as expected, do not show any electron trapping during irradiation by the native electron traps. Finally, a comparison of the isochronal detrapping behavior following irradiation and following avalanche injection of electrons has been made to estimate the extent of electron trapping. The results show that electron trapping by the nitridation-induced electron traps does not play the dominant role in improving radiation performance of RNO, though its contribution cannot be completely neglected for low oxide field irradiations

Electro activation of persulfate using iron sheet as low-cost electrode: the role of the operating conditions.

Science.gov (United States)

Silveira, Jefferson E; Cardoso, Tais O; Barreto-Rodrigues, Marcio; Zazo, Juan A; Casas, José A

2018-05-01

This work assesses the role of the operational conditions upon the electro-activation of persulfate (PS) using sacrificed iron electrode as a continuous low-cost Fe 2+ source. An aqueous phenol solution (100 mg L -1 ) was selected as model effluent. The studied variables include current density (1-10 mA cm -2 ), persulfate concentration (0.7-2.85 g L -1 ), temperature (30-90°C) and the solution conductivity (2.7-20.7 mS cm -1 ) using Na 2 SO 4 and NaCl as supporting electrolyte. A mineralization degree of around 80% with Na 2 SO 4 and 92% in presence of NaCl was achieved at 30°C using 2.15 g L -1 PS at the lowest current density tested (1 mA cm -2 ). Besides PS concentration, temperature was the main variable affecting the process. In the range of 30-70°C, it showed a positive effect, achieving TOC conversion above 95% (using Na 2 SO 4 under the previous conditions) along with a significant increase in iron sludge, which adversely affects the economy of the process. A lumped and simplified kinetic model based on persulfate consumption and TOC mineralization is suggested. The activation energy obtained for the TOC decay was 29 kJ mol -1 . An estimated operating cost of US$ 3.00 per m 3 was obtained, demonstrating the economic feasibility of this process.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : evaluation of alkaline persulfate digestion as an alternative to Kjeldahl digestion for determination of total and dissolved nitrogen and phosphorus in water

Science.gov (United States)

Patton, Charles J.; Kryskalla, Jennifer R.

2003-01-01

Alkaline persulfate digestion was evaluated and validated as a more sensitive, accurate, and less toxic alternative to Kjeldahl digestion for routine determination of nitrogen and phosphorus in surface- and ground-water samples in a large-scale and geographically diverse study conducted by U.S. Geological Survey (USGS) between October 1, 2001, and September 30, 2002. Data for this study were obtained from about 2,100 surface- and ground-water samples that were analyzed for Kjeldahl nitrogen and Kjeldahl phosphorus in the course of routine operations at the USGS National Water Quality Laboratory (NWQL). These samples were analyzed independently for total nitrogen and total phosphorus using an alkaline persulfate digestion method developed by the NWQL Methods Research and Development Program. About half of these samples were collected during nominally high-flow (April-June) conditions and the other half were collected during nominally low-flow (August-September) conditions. The number of filtered and whole-water samples analyzed from each flow regime was about equal.By operational definition, Kjeldahl nitrogen (ammonium + organic nitrogen) and alkaline persulfate digestion total nitrogen (ammonium + nitrite + nitrate + organic nitrogen) are not equivalent. It was necessary, therefore, to reconcile this operational difference by subtracting nitrate + nitrite concentra-tions from alkaline persulfate dissolved and total nitrogen concentrations prior to graphical and statistical comparisons with dissolved and total Kjeldahl nitrogen concentrations. On the basis of two-population paired t-test statistics, the means of all nitrate-corrected alkaline persulfate nitrogen and Kjeldahl nitrogen concentrations (2,066 paired results) were significantly different from zero at the p = 0.05 level. Statistically, the means of Kjeldahl nitrogen concentrations were greater than those of nitrate-corrected alkaline persulfate nitrogen concentrations. Experimental evidence strongly

Transparent oxide electronics from materials to devices

CERN Document Server

Martins, Rodrigo; Barquinha, Pedro; Pereira, Luis

2012-01-01

Transparent electronics is emerging as one of the most promising technologies for the next generation of electronic products, away from the traditional silicon technology. It is essential for touch display panels, solar cells, LEDs and antistatic coatings. The book describes the concept of transparent electronics, passive and active oxide semiconductors, multicomponent dielectrics and their importance for a new era of novel electronic materials and products. This is followed by a short history of transistors, and how oxides have revolutionized this field. It concludes with a glance at lo

Engineering complex oxide interfaces for oxide electronics

NARCIS (Netherlands)

Roy, Saurabh

2015-01-01

A complex interplay of physics and chemistry in transition metal oxides determines their electronic, magnetic, and ferroic properties enabling a wide range of applications of these materials. BiFeO_3, a canonical multiferroic system exhibits the interesting feature of enhanced conductivity on

Electron transport properties of indium oxide - indium nitride metal-oxide-semiconductor heterostructures

International Nuclear Information System (INIS)

Wang, C.Y.; Hauguth, S.; Polyakov, V.; Schwierz, F.; Cimalla, V.; Kups, T.; Himmerlich, M.; Schaefer, J.A.; Krischok, S.; Ambacher, O.; Morales, F.M.; Lozano, J.G.; Gonzalez, D.; Lebedev, V.

2008-01-01

The structural, chemical and electron transport properties of In 2 O 3 /InN heterostructures and oxidized InN epilayers are reported. It is shown that the accumulation of electrons at the InN surface can be manipulated by the formation of a thin surface oxide layer. The epitaxial In 2 O 3 /InN heterojunctions show an increase in the electron concentration due to the increasing band banding at the heterointerface. The oxidation of InN results in improved transport properties and in a reduction of the sheet carrier concentration of the InN epilayer very likely caused by a passivation of surface donors. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

76 FR 13358 - Persulfates From the People's Republic of China: Preliminary Results of the 2009-2010 Antidumping...

Science.gov (United States)

2011-03-11

...'s Republic of China: Preliminary Results of the 2009-2010 Antidumping Duty Administrative Review... conducting an administrative review of the antidumping duty order on persulfates from the People's Republic... review covers one producer/exporter of the subject merchandise, i.e., United Initiators (Shanghai) Co...

Degradation of Penicillin G by heat activated persulfate in aqueous solution.

Science.gov (United States)

Norzaee, Samira; Taghavi, Mahmoud; Djahed, Babak; Kord Mostafapour, Ferdos

2018-06-01

We used Heat Activated of Persulfate (HAP) to decompose Penicillin G (PEN G) in aqueous solution. The effect of pH (3-11), temperature (313-353 K), and initial concentration of Sodium Persulfate (SPS) (0.05-0.5 mM) on the decomposition level of PEN G were investigated. The residue of PEN G was determined by spectrophotometry at the wavelength of 290 nm. Also, the Chemical Oxygen Demand (COD) was measured in each experiment. The Total Organic Carbon (TOC) analysis was utilized for surveying the mineralization of PEN G. In addition, based on Arrhenius equation, the activation energy of PEN G decomposition was calculated. The results indicated that the maximum PEN G removal rate was obtained at pH 5 and by increasing the doses of SPS from 0.05 to 0.5 mM, the PEN G decomposition was enhanced. It was found that an increase in temperature is accompanied by an increase in removal efficiency of PEN G. The activation energy of the studied process was determined to be 94.8 kJ mol -1 , suggesting that a moderate activation energy is required for PEN G decomposition. The TOC measurements indicate that the HAP can efficiently mineralize PEN G. Besides, the presence of the scavengers significantly suppressed the HAP process to remove the PEN G. Overall, the results of this study demonstrate that using HAP process can be a suitable method for decomposing of PEN G in aqueous solutions. Copyright © 2018 Elsevier Ltd. All rights reserved.

75 FR 2112 - Persulfates From the People's Republic of China: Notice of Rescission of the 2008-2009...

Science.gov (United States)

2010-01-14

... (``FMC''), a domestic producer of persulfates, requested that the Department conduct an administrative..., 2009, in response to a request from FMC, the Department extended the deadline for FMC to withdraw its... This notice serves as a final reminder to importers of their responsibility under 19 CFR 351.402(f)(2...

Advances In Groundwater Remediation: Achieving Effective In Situ Delivery Of Chemical Oxidants And Amendments

DEFF Research Database (Denmark)

Siegrist, Robert L.; Crimi, Michelle; McCray, John E.

of organically contaminated sites. Many of the most prevalent organic contaminants of concern (COCs) at sites in urban areas (e.g., chlorinated solvents, motor and heating fuels) can be destroyed using oxidants such as catalyzed hydrogen peroxide (H2O2), potassium permanganate (KMnO4), sodium persulfate (Na2S2O8...

Patterning of high mobility electron gases at complex oxide interfaces

DEFF Research Database (Denmark)

Trier, Felix; Prawiroatmodjo, G. E. D. K.; von Soosten, Merlin

2015-01-01

Oxide interfaces provide an opportunity for electronics. However, patterning of electron gases at complex oxide interfaces is challenging. In particular, patterning of complex oxides while preserving a high electron mobility remains underexplored and inhibits the study of quantum mechanical effects...... of amorphous-LSM (a-LSM) thin films, which acts as a hard mask during subsequent depositions. Strikingly, the patterned modulation-doped interface shows electron mobilities up to ∼8 700 cm2/V s at 2 K, which is among the highest reported values for patterned conducting complex oxide interfaces that usually...... where extended electron mean free paths are paramount. This letter presents an effective patterning strategy of both the amorphous-LaAlO3/SrTiO3 (a-LAO/STO) and modulation-doped amorphous-LaAlO3/La7/8Sr1/8MnO3/SrTiO3 (a-LAO/LSM/STO) oxide interfaces. Our patterning is based on selective wet etching...

Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

Science.gov (United States)

Shevela, Dmitriy; Koroidov, Sergey; Najafpour, M Mahdi; Messinger, Johannes; Kurz, Philipp

2011-05-02

Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of μ-oxido manganese or μ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Secondary electron emission characteristics of oxide electrodes in flat electron emission lamp

Directory of Open Access Journals (Sweden)

Chang-Lin Chiang

2016-01-01

Full Text Available The present study concerns with the secondary electron emission coefficient, γ, of the cathode materials used in the newly developed flat electron emission lamp (FEEL devices, which essentially integrates the concept of using cathode for fluorescent lamp and anode for cathode ray tube (CRT to obtain uniform planar lighting. Three different cathode materials, namely fluorine-doped tin oxide (FTO, aluminum oxide coated FTO (Al2O3/FTO and magnesium oxide coated FTO (MgO/FTO were prepared to investigate how the variations of γ and working gases influence the performance of FEEL devices, especially in lowering the breakdown voltage and pressure of the working gases. The results indicate that the MgO/FTO bilayer cathode exhibited a relatively larger effective secondary electron emission coefficient, resulting in significant reduction of breakdown voltage to about 3kV and allowing the device to be operated at the lower pressure to generate the higher lighting efficiency.

Secondary electron emission characteristics of oxide electrodes in flat electron emission lamp

Energy Technology Data Exchange (ETDEWEB)

Chiang, Chang-Lin, E-mail: CLChiang@itri.org.tw; Li, Chia-Hung [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Road, Chutung 310, Taiwan (China); Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China); Zeng, Hui-Kai [Department of Electronic Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li 320, Taiwan (China); Li, Jung-Yu, E-mail: JY-Lee@itri.org.tw; Chen, Shih-Pu; Lin, Yi-Ping [Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Road, Chutung 310, Taiwan (China); Hsieh, Tai-Chiung; Juang, Jenh-Yih, E-mail: jyjuang@cc.nctu.edu.tw [Department of Electrophysics, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 300, Taiwan (China)

2016-01-15

The present study concerns with the secondary electron emission coefficient, γ, of the cathode materials used in the newly developed flat electron emission lamp (FEEL) devices, which essentially integrates the concept of using cathode for fluorescent lamp and anode for cathode ray tube (CRT) to obtain uniform planar lighting. Three different cathode materials, namely fluorine-doped tin oxide (FTO), aluminum oxide coated FTO (Al{sub 2}O{sub 3}/FTO) and magnesium oxide coated FTO (MgO/FTO) were prepared to investigate how the variations of γ and working gases influence the performance of FEEL devices, especially in lowering the breakdown voltage and pressure of the working gases. The results indicate that the MgO/FTO bilayer cathode exhibited a relatively larger effective secondary electron emission coefficient, resulting in significant reduction of breakdown voltage to about 3kV and allowing the device to be operated at the lower pressure to generate the higher lighting efficiency.

Titanium oxidation-reduction at low oxygen pressure under electron bombardment

International Nuclear Information System (INIS)

Brasca, R.; Passeggi, M.C.G.; Ferron, J.

2006-01-01

The effect of the electron bombardment on the first stages of the titanium oxidation process has been studied by means of Auger Electron Spectroscopy. Using Factor Analysis and the valence electron dependence behaviour of the titanium LMV Auger transition, we found that the process is strongly dependent on the oxygen pressure and electron current density. Depending on the irradiation conditions, films of different thickness and Ti oxidized states are obtained

Persistence of asthmatic response after ammonium persulfate-induced occupational asthma in mice.

Directory of Open Access Journals (Sweden)

Marta Ollé-Monge

Full Text Available INTRODUCTION: Since persulfate salts are an important cause of occupational asthma (OA, we aimed to study the persistence of respiratory symptoms after a single exposure to ammonium persulfate (AP in AP-sensitized mice. MATERIAL AND METHODS: BALB/c mice received dermal applications of AP or dimethylsulfoxide (DMSO on days 1 and 8. On day 15, they received a single nasal instillation of AP or saline. Airway hyperresponsiveness (AHR was assessed using methacholine provocation, while pulmonary inflammation was evaluated in bronchoalveolar lavage (BAL, and total serum immunoglobulin E (IgE, IgG1 and IgG2a were measured in blood at 1, 4, 8, 24 hours and 4, 8, 15 days after the single exposure to the causal agent. Histological studies of lungs were assessed. RESULTS: AP-treated mice showed a sustained increase in AHR, lasting up to 4 days after the challenge. There was a significant increase in the percentage of neutrophils 8 hours after the challenge, which persisted for 24 hours in AP-treated mice. The extent of airway inflammation was also seen in the histological analysis of the lungs from challenged mice. Slight increases in total serum IgE 4 days after the challenge were found, while IgG gradually increased further 4 to 15 days after the AP challenge in AP-sensitized mice. CONCLUSIONS: In AP-sensitized mice, an Ig-independent response is induced after AP challenge. AHR appears immediately, but airway neutrophil inflammation appears later. This response decreases in time; at early stages only respiratory and inflammatory responses decrease, but later on immunological response decreases as well.

Electron transfer oxidation of DNA radicals by paranitroacetophenone

Energy Technology Data Exchange (ETDEWEB)

Whillans, D W; Adams, G E [Mount Vernon Hospital, Northwood (UK)

1975-12-01

The reaction of a typical electron-affinic sensitizer, paranitroacetophenone (PNAP) with the model compounds thymine, thymidine, thymidylic acid, deoxyribose and single and double-stranded DNA has been investigated by pulse radiolysis. Radicals formed by one-electron reduction of the bases and of DNA reacted rapidly and efficiently with PNAP by electron transfer. A small yield of transfer (< 10 per cent) was also observed arising from oxidation of the radicals formed by the small proportion of OH which reacted at the sugar moieties in DNA. In contrast, electron transfer oxidation by PNAP of radicals formed by the addition of OH to the base moieties, e.g. thymine, was not an efficient process. Further, addition of the sensitizer to the thymine OH-adduct proceeded at a rate that was too low to measure the pulse radiolysis. We conclude that, since the major sites of OH reaction by DNA are the heterocyclic bases (> 80 per cent), oxidation of the resultant radicals is unlikely to be a major step in the mechanism of sensitization by this typical hypoxic-cell sensitizer.

Electronic properties of hafnium oxide: A contribution from defects and traps

Energy Technology Data Exchange (ETDEWEB)

Gritsenko, Vladimir A., E-mail: grits@isp.nsc.ru; Perevalov, Timofey V.; Islamov, Damir R., E-mail: damir@isp.nsc.ru

2016-02-15

In the present article, we give a review of modern data and latest achievements pertaining to the study of electronic properties of oxygen vacancies in hafnium oxide. Hafnium oxide is a key dielectric for use in many advanced silicon devices. Oxygen vacancies in hafnium oxide largely determine the electronic properties of the material. We show that the electronic transitions between the states due to oxygen vacancies largely determine the optical absorption and luminescent properties of hafnium oxide. We discuss the role of oxygen vacancies as traps that facilitate charge transport in hafnium oxide films. Also, we demonstrate the fact that the electrical conductivity in hafnium oxide is controlled by the phonon-assisted tunnelling of charge carriers between traps that were identified as oxygen vacancies.

Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

KAUST Repository

Baker, L. Robert

2011-08-18

The role of the oxide-metal interface in determining the activity and selectivity of chemical reactions catalyzed by metal particles on an oxide support is an important topic in science and industry. A proposed mechanism for this strong metal-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report an approximately 2-fold increase in the turnover rate of catalytic carbon monoxide oxidation on platinum nanoparticles supported on stoichiometric titanium dioxide (TiO2) when the TiO2 is made highly n-type by fluorine (F) doping. However, for nonstoichiometric titanium oxide (TiOX<2) the effect of F on the turnover rate is negligible. Studies of the titanium oxide electronic structure show that the energy of free electrons in the oxide determines the rate of reaction. These results suggest that highly n-type TiO2 electronically activates adsorbed oxygen (O) by electron spillover to form an active O- intermediate. © 2011 American Chemical Society.

Nanoroses of nickel oxides: Synthesis, electron tomography study, and application in CO oxidation and energy storage

KAUST Repository

Fihri, Aziz; Sougrat, Rachid; Baby, Rakhi Raghavan; Rahal, Raed; Cha, Dong Kyu; Hedhili, Mohamed N.; Bouhrara, Mohamed; Alshareef, Husam N.; Polshettiwar, Vivek

2012-01-01

Nickel oxide and mixed-metal oxide structures were fabricated by using microwave irradiation in pure water. The nickel oxide self-assembled into unique rose-shaped nanostructures. These nickel oxide roses were studied by performing electron

Electronic structure of the high-temperature oxide superconductors

International Nuclear Information System (INIS)

Pickett, W.E.

1989-01-01

Since the discovery of superconductivity above 30 K by Bednorz and Mueller in the La copper oxide system, the critical temperature has been raised to 90 K in YBa 2 Cu 3 O 7 and to 110 and 125 K in Bi-based and Tl-based copper oxides, respectively. In the two years since this Nobel-prize-winning discovery, a large number of electronic structure calculations have been carried out as a first step in understanding the electronic properties of these materials. In this paper these calculations (mostly of the density-functional type) are gathered and reviewed, and their results are compared with the relevant experimental data. The picture that emerges is one in which the important electronic states are dominated by the copper d and oxygen p orbitals, with strong hybridization between them. Photon, electron, and positron spectroscopies provide important information about the electronic states, and comparison with electronic structure calculations indicates that, while many features can be interpreted in terms of existing calculations, self-energy corrections (''correlations'') are important for a more detailed understanding. The antiferromagnetism that occurs in some regions of the phase diagram poses a particularly challenging problem for any detailed theory. The study of structural stability, lattice dynamics, and electron-phonon coupling in the copper oxides is also discussed. Finally, a brief review is given of the attempts so far to identify interaction constants appropriate for a model Hamiltonian treatment of many-body interactions in these materials

Metal oxide semiconductor thin-film transistors for flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Petti, Luisa; Vogt, Christian; Büthe, Lars; Cantarella, Giuseppe; Tröster, Gerhard [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Münzenrieder, Niko [Electronics Laboratory, Swiss Federal Institute of Technology, Zürich (Switzerland); Sensor Technology Research Centre, University of Sussex, Falmer (United Kingdom); Faber, Hendrik; Bottacchi, Francesca; Anthopoulos, Thomas D. [Department of Physics and Centre for Plastic Electronics, Imperial College London, London (United Kingdom)

2016-06-15

The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In

Synthesis of iron-based metal-organic framework MIL-53 as an efficient catalyst to activate persulfate for the degradation of Orange G in aqueous solution.

Science.gov (United States)

Pu, Mengjie; Guan, Zeyu; Ma, Yongwen; Wan, Jinquan; Wang, Yan; Brusseau, Mark L; Chi, Haiyuan

2018-01-05

A series of MIL-53(Fe) materials were synthesized using a solvothermal method under different temperature and time conditions and were used as catalysts to activate persulfate and degrade Orange G (OG). Influences of the above conditions on the crystal structure and catalytic behavior were investigated. Degradation of OG under different conditions was evaluated, and the possible activation mechanism was speculated. The results indicate that high synthesis temperature (larger than 170 °C) leads to poor crystallinity and low catalytic activity, while MIL-53(Fe) cannot fully develop at low temperature (100 or 120 °C). The extension of synthesis time from 5 h to 3 d can increase the crystallinity of the samples, but weakened the catalytic activity, which was caused by the reduction of BET surface area and the amount of Fe (II)-coordinative unsaturated sites. Among all the samples, MIL-53(Fe)-A possesses the best crystal structure and catalytic activity. In optimal conditions, OG can be totally decolorized after degradation for 90 min, and a removal rate of 74% for COD was attained after 120 min. The initial solution pH had great influence on OG degradation, with the greatest removal in acidic pH environment. ESR spectra showed that sulfate radical (SO 4 - ·), hydroxyl radical (OH·), persulfate radical (S 2 O 8 - ·), and superoxide radical (O 2 ·) exist in this system under acidic conditions. Furthermore, with the increase of pH, the relative amount of O 2 · increases while that of OH· and SO 4 - · decreases, resulting in a reduced oxidizing capacity of the system.

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

International Nuclear Information System (INIS)

Borgatti, F.; Torelli, P.; Panaccione, G.

2016-01-01

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

Energy Technology Data Exchange (ETDEWEB)

Borgatti, F., E-mail: francesco.borgatti@cnr.it [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Consiglio Nazionale delle Ricerche (CNR), via P. Gobetti 101, Bologna I-40129 (Italy); Torelli, P.; Panaccione, G. [Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, Trieste I-34149 (Italy)

2016-04-15

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Localized conductive patterning via focused electron beam reduction of graphene oxide

Energy Technology Data Exchange (ETDEWEB)

Kim, Songkil; Henry, Mathias [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Kulkarni, Dhaval D.; Zackowski, Paul; Jang, Seung Soon; Tsukruk, Vladimir V. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fedorov, Andrei G., E-mail: agf@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2015-03-30

We report on a method for “direct-write” conductive patterning via reduction of graphene oxide (GO) sheets using focused electron beam induced deposition (FEBID) of carbon. FEBID treatment of the intrinsically dielectric graphene oxide between two metal terminals opens up the conduction channel, thus enabling a unique capability for nanoscale conductive domain patterning in GO. An increase in FEBID electron dose results in a significant increase of the domain electrical conductivity with improving linearity of drain-source current vs. voltage dependence, indicative of a change of graphene oxide electronic properties from insulating to semiconducting. Density functional theory calculations suggest a possible mechanism underlying this experimentally observed phenomenon, as localized reduction of graphene oxide layers via interactions with highly reactive intermediates of electron-beam-assisted dissociation of surface-adsorbed hydrocarbon molecules. These findings establish an unusual route for using FEBID as nanoscale lithography and patterning technique for engineering carbon-based nanomaterials and devices with locally tailored electronic properties.

Carbon isotope fractionation of 1,1,1-trichloroethane during base-catalyzed persulfate treatment

International Nuclear Information System (INIS)

Marchesi, Massimo; Thomson, Neil R.; Aravena, Ramon; Sra, Kanwartej S.; Otero, Neus; Soler, Albert

2013-01-01

Highlights: • Treatability and C fractionation of 1,1,1-TCA by base-catalyzed S 2 O 8 2− was studied. • The rate of degradation of 1,1,1-TCA increased with a higher OH − :S 2 O 8 2− ratio. •Base-catalyzed S 2 O 8 2− can potentially treat recalcitrant compound like 1,1,1-TCA. • An enrichment factor of −7.0‰ independent of the OH − :S 2 O 8 2− ratio was obtained. • Carbon isotope can potentially be used to estimate the ISCO treatment efficacy. -- Abstract: The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S 2 O 8 2− ) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S 2 O 8 2− molar ratio from 0.2:1 to 8:1 enhanced the reaction rate of 1,1,1-TCA by a factor of ∼5 to yield complete (>99.9%) destruction. An average carbon isotope enrichment fractionation factor which was independent of the NaOH:S 2 O 8 2− molar ratio of −7.0 ± 0.2‰ was obtained. This significant carbon isotope fractionation and the lack of dependence on changes in the NaOH:S 2 O 8 2− molar ratio demonstrates that carbon isotope analysis can potentially be used in situ as a performance assessment tool to estimate the degradation effectiveness of 1,1,1-TCA by a base-catalyzed persulfate system

Participation of Low Molecular Weight Electron Carriers in Oxidative Protein Folding

Directory of Open Access Journals (Sweden)

József Mandl

2009-03-01

Full Text Available Oxidative protein folding is mediated by a proteinaceous electron relay system, in which the concerted action of protein disulfide isomerase and Ero1 delivers the electrons from thiol groups to the final acceptor. Oxygen appears to be the final oxidant in aerobic living organisms, although the existence of alternative electron acceptors, e.g. fumarate or nitrate, cannot be excluded. Whilst the protein components of the system are well-known, less attention has been turned to the role of low molecular weight electron carriers in the process. The function of ascorbate, tocopherol and vitamin K has been raised recently. In vitro and in vivo evidence suggests that these redox-active compounds can contribute to the functioning of oxidative folding. This review focuses on the participation of small molecular weight redox compounds in oxidative protein folding.

Peracetic acid as a superior oxidant for preparation of [123I]IBZM: a potential dopamine D-2 receptor imaging agent

International Nuclear Information System (INIS)

Kung, Meiping; Kung, H.F.

1989-01-01

Various oxidizing agents: chloramine-T, hydrogen peroxide, sodium persulfate, m-chloroperoxybenzoic acid and peracetic acid were examined as the oxidant for preparing radioiodinated IBZM ((S)-(-)-3-iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]benzami de), which is a useful dopamine D-2 receptor imaging agent. Of all the oxidizing agents tested, peracetic acid appears to be the best agent for no-carrier added radioiodination. The advantages of using peracetic acid as the oxidant for the preparation of [ 125 I] or [ 123 I] IBZM include: high radiochemical yield, high radiochemical purity, and short reaction time at room temperature. (Author)

Relation between electron- and photon-caused oxidation in EUVL optics

Science.gov (United States)

Malinowski, Michael E.; Steinhaus, Charles A.; Meeker, Donald E.; Clift, W. Miles; Klebanoff, Leonard E.; Bajt, Sasa

2003-06-01

Extreme ultraviolet (EUV)-induced oxidation of silicon-capped, [Mo/Si] multilayer mirrors in the presence of background levels of water vapor is recognized as one of the most serious threats to multilayer lifetime since oxidation of the top silicon layer is an irreversible process. The current work directly compares the oxidation on a silicon-capped, [Mo/Si] multilayers caused by EUV photons with the oxidation caused by 1 keV electrons in the presence of the same water vapor environment (2 x 10-6 Torr). Similar, 4 nm, silicon-capped, [Mo/Si] multilayer mirror samples were exposed to photons (95.3 eV) + water vapor at the ALS, LBNL, and also to a 1 keV electron beam + water vapor in separate experimental systems. The results of this work showed that the oxidation produced by ~1 µA of e-beam current was found to be equivalent to that produced by ~1 mW of EUV exposure. These results will help allow the use of 1 keV electrons beams, instead of EUV photons, to perform environmental testing of multilayers in a low-pressure water environment and to more accurately determine projected mirror lifetimes based on the electron beam exposures.

Self-limited kinetics of electron doping in correlated oxides

International Nuclear Information System (INIS)

Chen, Jikun; Zhou, You; Jiang, Jun; Shi, Jian; Ramanathan, Shriram; Middey, Srimanta; Chakhalian, Jak; Chen, Nuofu; Chen, Lidong; Shi, Xun; Döbeli, Max

2015-01-01

Electron doping by hydrogenation can reversibly modify the electrical properties of complex oxides. We show that in order to realize large, fast, and reversible response to hydrogen, it is important to consider both the electron configuration on the transition metal 3d orbitals, as well as the thermodynamic stability in nickelates. Specifically, large doping-induced resistivity modulations ranging several orders of magnitude change are only observed for rare earth nickelates with small ionic radii on the A-site, in which case both electron correlation effects and the meta-stability of Ni 3+ are important considerations. Charge doping via metastable incorporation of ionic dopants is of relevance to correlated oxide-based devices where advancing approaches to modify the ground state electronic properties is an important problem

Transparent Oxide Semiconductors for Emerging Electronics

KAUST Repository

Caraveo-Frescas, Jesus Alfonso

2013-11-01

Transparent oxide electronics have emerged as promising materials to shape the future of electronics. While several n-type oxides have been already studied and demonstrated feasibility to be used as active materials in thin film transistors, high performance p-type oxides have remained elusive. This dissertation is devoted to the study of transparent p-type oxide semiconductor tin monoxide and its use in the fabrication of field effect devices. A complete study on the deposition of tin monoxide thin films by direct current reactive magnetron sputtering is performed. Carrier density, carrier mobility and conductivity are studied over a set of deposition conditions where p-type conduction is observed. Density functional theory simulations are performed in order to elucidate the effect of native defects on carrier mobility. The findings on the electrical properties of SnO thin films are then translated to the fabrication of thin films transistors. The low processing temperature of tin monoxide thin films below 200 oC is shown advantageous for the fabrication of fully transparent and flexible thin film transistors. After careful device engineering, including post deposition annealing temperature, gate dielectric material, semiconductor thickness and source and drain electrodes material, thin film transistors with record device performance are demonstrated, achieving a field effect mobility >6.7 cm2V-1s-1. Device performance is further improved to reach a field effect mobility of 10.8 cm2V-1s-1 in SnO nanowire field effect transistors fabricated from the sputtered SnO thin films and patterned by electron beam lithography. Downscaling device dimension to nano scale is shown beneficial for SnO field effect devices not only by achieving a higher hole mobility but enhancing the overall device performance including better threshold voltage, subthreshold swing and lower number of interfacial defects. Use of p-type semiconductors in nonvolatile memory applications is then

Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

KAUST Repository

Ali, Haider; Yang, Xinbo; Weber, Klaus; Schoenfeld, Winston V.; Davis, Kristopher O.

2017-01-01

In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21

Carbonate and Chloride Scavenging in S₂O₈^2-/Fe²⁺/Citric Acid Oxidation of PCE

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Mortensen, Lars

, and natural attenuation. In the 1990s the first report on in situ chemical oxidation were published. Modified Fenton's reagent was the first technique investigated and used in full scale. Shortly after ozone and permanganate came into use. In the past few years persulfate has provided yet another option...

Method of isolation of traces of americium by using the +6 oxidation state properties

International Nuclear Information System (INIS)

Kwinta, Jean; Michel, Jean-Jacques

1969-05-01

The authors present a method to separate traces of americium from a solution containing fission products and actinides. This method comprises the following steps: firstly, the oxidation of americium at the +6 state by ammonium persulfate and carrying over of actinides and III and IV lanthanides by lanthanum fluoride; secondly, the reduction by hydrazine of the oxidized americium and carrying over of the reduced americium by lutetium fluoride; and thirdly, the americium-lutetium separation by selective extractions either with di 2 ethyl hexyl phosphoric acid, or by fractionated elution on an anionic resin column by a mixture of nitric acid and methanol [fr

Electronic structure investigation of oxidized aluminium films with electron momentum spectroscopy

International Nuclear Information System (INIS)

Guo, X.; Canney, S.; Kheifets, A.S.; Vos, M.; Fang, Z.; Utteridge, S.; McCarthy, I.E.; Weigold, E.

1996-09-01

Electron momentum spectroscopy (EMS) of (e, 2e) measurements with oxidized aluminium thin films have been performed. Due to the surface sensitive mature of the EMS spectrometer employed the measured (e, 2e) events come from the front oxidized layer as viewed by the electron detectors. The measurements show clearly two major features in the spectral momentum density distribution and they are related to the upper valence band and the lower valence band of aluminum oxide. The first is a 'dual parabola' energy-momentum dispersion pattern spanning about 8 eV in the upper valence band. This 'dual parabola' pattern has been qualitatively reproduced by a linear muffin-tin orbital (LMTO) calculation on spherically averaged α-A1 2 O 3 with nearly the same energy span. In the lower valence band, the LMTO calculation indicates a dispersion spanning about 5 eV, and the measured spectral momentum density plot shows a similar 'bowl' shape but with less dispersion. The possible causes which blur the dispersion in the lower valence band are discussed. Other features in the spectral momentum density distribution are also discussed and compared with the LMTO calculation. 45 refs., 1 tab., 10 figs

Latest progress in gallium-oxide electronic devices

Science.gov (United States)

Higashiwaki, Masataka; Wong, Man Hoi; Konishi, Keita; Nakata, Yoshiaki; Lin, Chia-Hung; Kamimura, Takafumi; Ravikiran, Lingaparthi; Sasaki, Kohei; Goto, Ken; Takeyama, Akinori; Makino, Takahiro; Ohshima, Takeshi; Kuramata, Akito; Yamakoshi, Shigenobu; Murakami, Hisashi; Kumagai, Yoshinao

2018-02-01

Gallium oxide (Ga2O3) has emerged as a new competitor to SiC and GaN in the race toward next-generation power switching and harsh environment electronics by virtue of the excellent material properties and the relative ease of mass wafer production. In this proceedings paper, an overview of our recent development progress of Ga2O3 metal-oxide-semiconductor field-effect transistors and Schottky barrier diodes will be reported.

Carbon isotope fractionation of 1,1,1-trichloroethane during base-catalyzed persulfate treatment

Energy Technology Data Exchange (ETDEWEB)

Marchesi, Massimo, E-mail: m2marche@uwaterloo.ca [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Thomson, Neil R. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Aravena, Ramon [Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Sra, Kanwartej S. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada); Otero, Neus; Soler, Albert [Departament de Cristal.lographia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Barcelona, Spain 08028 (Spain)

2013-09-15

Highlights: • Treatability and C fractionation of 1,1,1-TCA by base-catalyzed S{sub 2}O{sub 8}{sup 2−} was studied. • The rate of degradation of 1,1,1-TCA increased with a higher OH{sup −}:S{sub 2}O{sub 8}{sup 2−} ratio. •Base-catalyzed S{sub 2}O{sub 8}{sup 2−} can potentially treat recalcitrant compound like 1,1,1-TCA. • An enrichment factor of −7.0‰ independent of the OH{sup −}:S{sub 2}O{sub 8}{sup 2−} ratio was obtained. • Carbon isotope can potentially be used to estimate the ISCO treatment efficacy. -- Abstract: The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S{sub 2}O{sub 8}{sup 2−}) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio from 0.2:1 to 8:1 enhanced the reaction rate of 1,1,1-TCA by a factor of ∼5 to yield complete (>99.9%) destruction. An average carbon isotope enrichment fractionation factor which was independent of the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio of −7.0 ± 0.2‰ was obtained. This significant carbon isotope fractionation and the lack of dependence on changes in the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio demonstrates that carbon isotope analysis can potentially be used in situ as a performance assessment tool to estimate the degradation effectiveness of 1,1,1-TCA by a base-catalyzed persulfate system.

Structural changes in graphene oxide thin film by electron-beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Tyagi, Chetna, E-mail: tchetna91@gmail.com [Materials Science Group, Inter University Accelerator Centre, New Delhi 67 (India); Lakshmi, G.B.V.S.; Kumar, Sunil; Tripathi, Ambuj [Materials Science Group, Inter University Accelerator Centre, New Delhi 67 (India); Avasthi, D.K. [Amity University, Noida 201313, Uttar Pradesh (India)

2016-07-15

Although we have a whole class of 2D materials, graphene has drawn much attention for its excellent electronic, optical, thermal and mechanical properties. Recent researches have shown its large scale production by the reduction of graphene oxide either thermally, chemically or electrochemically. Although the structure of graphene oxide is inhomogeneous and hence complicated due to the presence of organic moieties e.g. epoxy, carboxylic acid, hydroxyl groups etc., its properties can be tuned by reduction according to desired application. The aim of this work is to synthesize continuous thin film of graphene oxide using commercially available graphene oxide solution and to study its reduction by 25 keV electron beam irradiation at fluences varying from 2 × 10{sup 11} to 2 × 10{sup 13} e{sup −}/cm{sup 2}. Our studies using X-ray diffraction, Raman microscopy and UV–Vis spectroscopy showed that electron-beam irradiation is an effective tool for reduction of graphene oxide and for tuning its band gap.

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

Energy Technology Data Exchange (ETDEWEB)

Guo, Yongling [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Bo, Maolin [Yangtze Normal University, College of Mechanical and Electrical Engineering, Chongqing 408100 (China); Wang, Yan [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Sun, Chang Q. [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China)

2017-02-28

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O{sup 2−} lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta{sup +} electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta{sup +}; the sp{sup 3}-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent

Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

International Nuclear Information System (INIS)

Guo, Yongling; Bo, Maolin; Wang, Yan; Liu, Yonghui; Sun, Chang Q.; Huang, Yongli

2017-01-01

Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O"2"− lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta"+ electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta"+; the sp"3-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent insight into the

Oxide-cathode activation and surface temperature calculation of electron cooler

International Nuclear Information System (INIS)

Li Jie; Yang Xiaodong; Mao Lijun; Li Guohong; Yuan Youjin; Liu Zhanwen; Zhang Junhui; Yang Xiaotian; Ma Xiaoming; Yan Tailai

2011-01-01

The pollution on electron gun ceramic insulation of electron cooler restricted the operation of electron cooler at HIRFL-CSR main ring. To cool and accumulate ion beam well, the pollution was cleared and a new oxide-coated cathode was assembled. The processes of cathode replacement,vacuum chamber baking-out, and thermal decomposition of coating binders and alkaline earth metal carbonates, and cathode activation are presented. The electron gun perveance of 10.6 μA/V 1.5 was attained under the heating power of 60 W. The typical surface temperature of oxide-coated cathode that is calculated through grey-body radiation is 1 108 K which shows a comparable result to the experimental measurement 1 078 K. The perveance growth of electron gun during the electron cooler operation is also explained by partial activation of the cathode. (authors)

How ISCO Can Interfere in Soil Pore Distribution and Solute Transport

Science.gov (United States)

Favero, M.; Freitas, J. G.; Furquim, S. A. C.; Thomson, N. R.; Cooper, M.

2016-12-01

Recently in situ chemical oxidation (ISCO) has been a remedy of choice for sites contaminated with organic compounds. However, the impact of the chemical oxidant on soil properties and, therefore, on solute transport and remediation efficiency still lacks understanding. This research effort sought to evaluate the changes in soil physical properties and solute transport behavior in a typical tropical soil (Oxisol) resulting from exposure to persulfate. The Oxisol used had a microaggregate structure, resulting in a relatively high hydraulic conductivity despite the high clay content (67%). One-dimensional laboratory experiments were performed using a saturated undisturbed column. The injection of an ideal tracer (bromide), a reactive tracer (phenol) and persulfate (12 ± 1 gL-1 for 30 d) were performed consecutively. The tracer tests were repeated following persulfate injection. Transport parameters (longitudinal dispersivity: αL and retardation factor: R) and the effective porosity (ne) were obtained by fitting the breakthrough curves with an analytical solution for one-dimensional transport. Micromorphological analyses of porosity were conducted on impregnated soil blocks from control and oxidized systems. The bromide and phenol tracer test data yielded αL of 2.431 ± 0.002 cm, ne of 41.99 ± 1.52 %, R of 1.10, and a first-order decay rate coefficient of 6.5x10-5 min-1 prior to persulfate exposure. The effluent persulfate concentration stabilized at C/Co of 0.8 after 4 d of injection and the breakthrough was delayed relative to bromide. Concurrent with the breakthrough of persulfate, the pH decreased and a progressive release of Al (III) over the first 4 d with subsequent stabilization were observed. Following persulfate exposures the hydraulic conductivity increased about one-order of magnitude. Micromorphological analysis showed that persulfate produced alterations in poroids types, with an increase of complex packing voids. It was verified that persulfate

A comparison between different oxide dispersion strengthened ferritic steel ongoing in situ oxide dissolution in High Voltage Electron Microscope

International Nuclear Information System (INIS)

Monnet, I.; Van den Berghe, T.; Dubuisson, Ph.

2012-01-01

ODS materials are considered for nuclear applications but previous experimental studies have shown a partial dissolution of some oxides under neutron irradiation. In this work, electron irradiations were used to evaluate the stability of the oxides depending on the chemical composition of the oxide dispersion. Four ferritic steels based on EM10 (Fe–9Cr–1Mo) and reinforced respectively by Al 2 O 3 , MgO, MgAl 2 O 4 and Y 2 O 3 , were studied. These materials were irradiated with 1 MeV or 1.2 MeV electrons in a High Voltage Electron Microscope. This technique allows to follow one single oxide and to determine the evolution of its size during the irradiation. In situ HVEM observations indicate that the dissolution rate depends on the chemical composition of the oxide, on the temperature and on the irradiation dose.

Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

DEFF Research Database (Denmark)

Katz, Jordan E; Zhang, Xiaoyi; Attenkofer, Klaus

2012-01-01

Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest....... To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio...

Electronic-Reconstruction-Enhanced Tunneling Conductance at Terrace Edges of Ultrathin Oxide Films.

Science.gov (United States)

Wang, Lingfei; Kim, Rokyeon; Kim, Yoonkoo; Kim, Choong H; Hwang, Sangwoon; Cho, Myung Rae; Shin, Yeong Jae; Das, Saikat; Kim, Jeong Rae; Kalinin, Sergei V; Kim, Miyoung; Yang, Sang Mo; Noh, Tae Won

2017-11-01

Quantum mechanical tunneling of electrons across ultrathin insulating oxide barriers has been studied extensively for decades due to its great potential in electronic-device applications. In the few-nanometers-thick epitaxial oxide films, atomic-scale structural imperfections, such as the ubiquitously existed one-unit-cell-high terrace edges, can dramatically affect the tunneling probability and device performance. However, the underlying physics has not been investigated adequately. Here, taking ultrathin BaTiO 3 films as a model system, an intrinsic tunneling-conductance enhancement is reported near the terrace edges. Scanning-probe-microscopy results demonstrate the existence of highly conductive regions (tens of nanometers wide) near the terrace edges. First-principles calculations suggest that the terrace-edge geometry can trigger an electronic reconstruction, which reduces the effective tunneling barrier width locally. Furthermore, such tunneling-conductance enhancement can be discovered in other transition metal oxides and controlled by surface-termination engineering. The controllable electronic reconstruction can facilitate the implementation of oxide electronic devices and discovery of exotic low-dimensional quantum phases. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxide bipolar electronics: materials, devices and circuits

International Nuclear Information System (INIS)

Grundmann, Marius; Klüpfel, Fabian; Karsthof, Robert; Schlupp, Peter; Schein, Friedrich-Leonhard; Splith, Daniel; Yang, Chang; Bitter, Sofie; Von Wenckstern, Holger

2016-01-01

We present the history of, and the latest progress in, the field of bipolar oxide thin film devices. As such we consider primarily pn-junctions in which at least one of the materials is a metal oxide semiconductor. A wide range of n-type and p-type oxides has been explored for the formation of such bipolar diodes. Since most oxide semiconductors are unipolar, challenges and opportunities exist with regard to the formation of heterojunction diodes and band lineups. Recently, various approaches have led to devices with high rectification, namely p-type ZnCo 2 O 4 and NiO on n-type ZnO and amorphous zinc-tin-oxide. Subsequent bipolar devices and applications such as photodetectors, solar cells, junction field-effect transistors and integrated circuits like inverters and ring oscillators are discussed. The tremendous progress shows that bipolar oxide electronics has evolved from the exploration of various materials and heterostructures to the demonstration of functioning integrated circuits. Therefore a viable, facile and high performance technology is ready for further exploitation and performance optimization. (topical review)

Cooperative electrocatalytic alcohol oxidation with electron-proton-transfer mediators

Science.gov (United States)

Badalyan, Artavazd; Stahl, Shannon S.

2016-07-01

The electrochemical oxidation of alcohols is a major focus of energy and chemical conversion efforts, with potential applications ranging from fuel cells to biomass utilization and fine-chemical synthesis. Small-molecule electrocatalysts for processes of this type are promising targets for further development, as demonstrated by recent advances in nickel catalysts for electrochemical production and oxidation of hydrogen. Complexes with tethered amines that resemble the active site of hydrogenases have been shown both to catalyse hydrogen production (from protons and electrons) with rates far exceeding those of such enzymes and to mediate reversible electrocatalytic hydrogen production and oxidation with enzyme-like performance. Progress in electrocatalytic alcohol oxidation has been more modest. Nickel complexes similar to those used for hydrogen oxidation have been shown to mediate efficient electrochemical oxidation of benzyl alcohol, with a turnover frequency of 2.1 per second. These compounds exhibit poor reactivity with ethanol and methanol, however. Organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidine N-oxyl), are the most widely studied electrocatalysts for alcohol oxidation. These catalysts exhibit good activity (1-2 turnovers per second) with a wide range of alcohols and have great promise for electro-organic synthesis. Their use in energy-conversion applications, however, is limited by the high electrode potentials required to generate the reactive oxoammonium species. Here we report (2,2‧-bipyridine)Cu/nitroxyl co-catalyst systems for electrochemical alcohol oxidation that proceed with much faster rates, while operating at an electrode potential a half-volt lower than that used for the TEMPO-only process. The (2,2‧-bipyridine)Cu(II) and TEMPO redox partners exhibit cooperative reactivity and exploit the low-potential, proton-coupled TEMPO/TEMPOH redox process rather than the high-potential TEMPO/TEMPO+ process. The results show how

Nanoroses of nickel oxides: Synthesis, electron tomography study, and application in CO oxidation and energy storage

KAUST Repository

Fihri, Aziz

2012-04-11

Nickel oxide and mixed-metal oxide structures were fabricated by using microwave irradiation in pure water. The nickel oxide self-assembled into unique rose-shaped nanostructures. These nickel oxide roses were studied by performing electron tomography with virtual cross-sections through the particles to understand their morphology from their interior to their surface. These materials exhibited promising performance as nanocatalysts for CO oxidation and in energy storage devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic Structure Control of Tungsten Oxide Activated by Ni for Ultrahigh-Performance Supercapacitors.

Science.gov (United States)

Meng, Tian; Kou, Zongkui; Amiinu, Ibrahim Saana; Hong, Xufeng; Li, Qingwei; Tang, Yongfu; Zhao, Yufeng; Liu, Shaojun; Mai, Liqiang; Mu, Shichun

2018-04-17

Tuning the electron structure is of vital importance for designing high active electrode materials. Here, for boosting the capacitive performance of tungsten oxide, an atomic scale engineering approach to optimize the electronic structure of tungsten oxide by Ni doping is reported. Density functional theory calculations disclose that through Ni doping, the density of state at Fermi level for tungsten oxide can be enhanced, thus promoting its electron transfer. When used as electrode of supercapacitors, the obtained Ni-doped tungsten oxide with 4.21 at% Ni exhibits an ultrahigh mass-specific capacitance of 557 F g -1 at the current density of 1 A g -1 and preferable durability in a long-term cycle test. To the best of knowledge, this is the highest supercapacitor performance reported so far in tungsten oxide and its composites. The present strategy demonstrates the validity of the electronic structure control in tungsten oxide via introducing Ni atoms for pseudocapacitors, which can be extended to other related fields as well. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

DEFF Research Database (Denmark)

Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

2013-01-01

photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported....... We addressed this topic by performing femtosecond transient absorption (TA) measurements of aqueous suspensions of uncoated and DCF-sensitized iron oxide and oxyhydroxide nanoparticles, and an aqueous iron(iii)–dye complex. Following light absorption, excited state relaxation times of the dye of 115...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...

Carbonate and Chloride Scavenging in H₂O₂/S₂O₈^2-/Fe²⁺ Oxidation of PCE

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen

2009-01-01

, and natural attenuation. In the 1990s the first report on in situ chemical oxidation were published. Modified Fenton's reagent was the first technique investigated and used in full scale. Shortly after ozone and permanganate came into use. In the past few years persulfate has provided yet another option...

Graphene oxide and reduced graphene oxide studied by the XRD, TEM and electron spectroscopy methods

International Nuclear Information System (INIS)

Stobinski, L.; Lesiak, B.; Malolepszy, A.; Mazurkiewicz, M.; Mierzwa, B.; Zemek, J.; Jiricek, P.; Bieloshapka, I.

2014-01-01

Highlights: • Graphene oxide (FL-GOc) and reduced graphene oxide (FL-RGOc): XRD, TEM, XPS, REELS. • FL-GOc: stacking nanostructure—22 × 6 nm (DxH), 0.9 nm layers separation (XRD). • FL-RGOc: stacking nanostructure—8 × 1 nm (DxH), 0.4 nm layers separation (XRD). • Reduction: oxygen group degradation, decreasing distance between graphene layers. • Number of graphene layers in stacking nanostructure: 6–7 (FL-GOc), 2–3 (FL-RGOc). - Abstract: The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS). The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22 × 6 nm average diameter by height with the distance of 0.9 nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8 × 1 nm average diameter by height stacking nanostructure with the distance of 0.4 nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp 3 bonds and high content of functional oxygen groups (hydroxyl—C-OH, epoxy—C-O-C, carbonyl—C=O, carboxyl—C-OOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp 3 content to 11.4–20.3 at% and also the content of C-O-C and C=O groups, accompanied by increasing content of C-OH and C-OOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups

The influence of oxidation properties on the electron emission characteristics of porous silicon

International Nuclear Information System (INIS)

He, Li; Zhang, Xiaoning; Wang, Wenjiang; Wei, Haicheng

2016-01-01

Highlights: • Evaluated the oxidation properties of porous silicon from semi-quantitative methods. • Discovered the relationship between oxidation properties and emission characteristics. • Revealed the micro-essence of the electron emission of the porous silicon. - Abstract: In order to investigate the influence of oxidation properties such as oxygen content and its distribution gradient on the electron emission characteristics of porous silicon (PS) emitters, emitters with PS thickness of 8 μm, 5 μm, and 3 μm were prepared and then oxidized by electrochemical oxidation (ECO) and ECO-RTO (rapid thermal oxidation) to get different oxidation properties. The experimental results indicated that the emission current density, efficiency, and stability of the PS emitters are mainly determined by oxidation properties. The higher oxygen content and the smaller oxygen distribution gradient in the PS layer, the larger emission current density and efficiency we noted. The most favorable results occurred for the PS emitter with the smallest oxygen distribution gradient and the highest level of oxygen content, with an emission current density of 212.25 μA/cm"2 and efficiency of 59.21‰. Additionally, it also demonstrates that thick PS layer benefits to the emission stability due to its longer electron acceleration tunnel. The FN fitting plots indicated that the effective emission areas of PS emitters can be enlarged and electron emission thresholds is decreased because of the higher oxygen content and smaller distribution gradient, which were approved by the optical micrographs of top electrode of PS emitters before and after electron emission.

The influence of oxidation properties on the electron emission characteristics of porous silicon

Energy Technology Data Exchange (ETDEWEB)

He, Li [Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, Xiaoning, E-mail: znn@mail.xjtu.edu.cn [Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049 (China); Wang, Wenjiang [Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi’an Jiaotong University, Xi’an 710049 (China); Wei, Haicheng [School of Electrical and Information Engineering, Beifang University of Nationalities, Yinchuan750021 (China)

2016-09-30

Highlights: • Evaluated the oxidation properties of porous silicon from semi-quantitative methods. • Discovered the relationship between oxidation properties and emission characteristics. • Revealed the micro-essence of the electron emission of the porous silicon. - Abstract: In order to investigate the influence of oxidation properties such as oxygen content and its distribution gradient on the electron emission characteristics of porous silicon (PS) emitters, emitters with PS thickness of 8 μm, 5 μm, and 3 μm were prepared and then oxidized by electrochemical oxidation (ECO) and ECO-RTO (rapid thermal oxidation) to get different oxidation properties. The experimental results indicated that the emission current density, efficiency, and stability of the PS emitters are mainly determined by oxidation properties. The higher oxygen content and the smaller oxygen distribution gradient in the PS layer, the larger emission current density and efficiency we noted. The most favorable results occurred for the PS emitter with the smallest oxygen distribution gradient and the highest level of oxygen content, with an emission current density of 212.25 μA/cm{sup 2} and efficiency of 59.21‰. Additionally, it also demonstrates that thick PS layer benefits to the emission stability due to its longer electron acceleration tunnel. The FN fitting plots indicated that the effective emission areas of PS emitters can be enlarged and electron emission thresholds is decreased because of the higher oxygen content and smaller distribution gradient, which were approved by the optical micrographs of top electrode of PS emitters before and after electron emission.

Optimizing COD removal from greywater by photoelectro-persulfate process using Box-Behnken design: assessment of effluent quality and electrical energy consumption.

Science.gov (United States)

Ahmadi, Mehdi; Ghanbari, Farshid

2016-10-01

Greywater (GW) is a potential source for water reuse in various applications. However, GW treatment is still a vital issue in water reuse in cases of environmental standards and risk to public health. This study investigates optimization and modeling of a hybrid process for COD removal from GW. Persulfate (PS) was simultaneously activated by electrogenerated ferrous ion (EC) and UV to generate sulfate radical. Photoelectro-persulfate (PEPS) was optimized by Box-Behnken design and the effects of four variables (pH, PS dosage, current density, and electrolysis time) were evaluated on COD removal. The results and several coefficients showed that the obtained model was acceptable for predicting the COD removal. Moreover, under optimum conditions (pH = 6.9, PS = 8.8 mM, current density = 2.0 mA/cm(2), and 49.3 min electrolysis time), BOD5, turbidity, TSS, phosphate, and UV254 were effectively removed and COD and BOD5 values reached to discharge standards. Different configurations of the processes were assessed for COD removal. The order of COD removal efficiency followed: PS electrical energy consumption was far less than that of photolysis process in hybrid PEPS process.

Effect of pressure on f-electron delocalization and oxidation in actinide dioxides

Energy Technology Data Exchange (ETDEWEB)

Petit, L., E-mail: leon.petit@stfc.ac.uk [Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Szotek, Z.; Temmerman, W.M. [Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Stocks, G.M. [Materials Science and Technology Division and Center for Defect Physics, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Svane, A. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

2014-08-01

Using first principles calculations, we have investigated f-electron delocalization and oxidation in the actinide dioxides under pressure. Whilst UO{sub 2} is found on the verge of an insulator to metal transition at the equilibrium volume, increasingly larger pressures are required to delocalize f-electrons in NpO{sub 2}, PuO{sub 2}, and AmO{sub 2}, respectively 49, 112, and 191 GPa. Compared to this broad range of pressures, the experimentally observed structural transitions, in all four dioxides, occur between 30 and 40 GPa, which leads us to conclude that the associated volume collapse is not due to f-electron delocalization. In contrast, oxidation of the dioxides is found to be linked to the degree of f-electron localization, but it emerges that for naturally occurring pressures (<10 GPa), higher oxides only exist for UO{sub 2}.

Interpretation of electron beam induced charging of oxide layers in a transistor studied using electron holography

DEFF Research Database (Denmark)

Ubaldi, F; Pozzi, G; Kasama, Takeshi

2010-01-01

Off-axis electron holography has been used to characterize a linear array of transistors, which was prepared for examination in cross-sectional geometry in the transmission electron microscope using focused ion beam milling. In reconstructed phase images, regions of silicon oxide that are located...... into account the mean inner potential of the specimen and the perturbed vacuum reference wave. The simulations suggest that the oxide layers contain a uniform volume density of positive charge and that the elliptical contours result from the combined effect of the electrostatic potential in the specimen...

Graphene oxide overprints for flexible and transparent electronics

Energy Technology Data Exchange (ETDEWEB)

Rogala, M., E-mail: rogala@uni.lodz.pl; Wlasny, I.; Kowalczyk, P. J.; Busiakiewicz, A.; Kozlowski, W.; Klusek, Z. [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz (Poland); Dabrowski, P.; Lipinska, L.; Jagiello, J.; Aksienionek, M.; Strupinski, W.; Krajewska, A. [Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw (Poland); Sieradzki, Z. [Electrotechnological Company QWERTY Ltd., Siewna 21, 94-250 Lodz (Poland); Krucinska, I.; Puchalski, M.; Skrzetuska, E. [Department of Material and Commodity Sciences and Textile Metrology, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz (Poland)

2015-01-26

The overprints produced in inkjet technology with graphene oxide dispersion are presented. The graphene oxide ink is developed to be fully compatible with standard industrial printers and polyester substrates. Post-printing chemical reduction procedure is proposed, which leads to the restoration of electrical conductivity without destroying the substrate. The presented results show the outstanding potential of graphene oxide for rapid and cost efficient commercial implementation to production of flexible electronics. Properties of graphene-based electrodes are characterized on the macro- and nano-scale. The observed nano-scale inhomogeneity of overprints' conductivity is found to be essential in the field of future industrial applications.

Electronically conductive perovskite-based oxide nanoparticles and films for optical sensing applications

Science.gov (United States)

Ohodnicki, Jr., Paul R; Schultz, Andrew M

2015-04-28

The disclosure relates to a method of detecting a change in a chemical composition by contacting a electronically conducting perovskite-based metal oxide material with a monitored stream, illuminating the electronically conducting perovskite-based metal oxide with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The electronically conducting perovskite-based metal oxide has a perovskite-based crystal structure and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The electronically conducting perovskite-based metal oxide has an empirical formula A.sub.xB.sub.yO.sub.3-.delta., where A is at least a first element at the A-site, B is at least a second element at the B-site, and where 0.8perovskite-based oxides include but are not limited to La.sub.1-xSr.sub.xCoO.sub.3, La.sub.1-xSr.sub.xMnO.sub.3, LaCrO.sub.3, LaNiO.sub.3, La.sub.1-xSr.sub.xMn.sub.1-yCr.sub.yO.sub.3, SrFeO.sub.3, SrVO.sub.3, La-doped SrTiO.sub.3, Nb-doped SrTiO.sub.3, and SrTiO.sub.3-.delta..

Evidence for Single Metal Two Electron Oxidative Addition and Reductive Elimination at Uranium

OpenAIRE

Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; Mcinnes, Eric; Tuna, Floriana; Wooles, Ashley; Maron, Laurent; Liddle, Stephen

2017-01-01

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here, we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido compl...

Time-dependence hole and electron trapping effects in SIMOX buried oxides

International Nuclear Information System (INIS)

Boesch, H.E. Jr.; Taylor, T.L.; Hite, L.R.; Bailey, W.E.

1990-01-01

Back-channel threshold shift associated with the buried oxide layers of separation by implanted oxygen (SIMOX) and zone-melted recrystallization (ZMR) field-effect transistors (FETs) was measured following pulsed irradiation as a function of temperature and back-gate bias using a fast time-resolved I-V measurement technique. The SIMOX FETs showed large initial negative voltage shifts at 0.2 ms after irradiation followed by temperature- and bias-dependent additional negative shifts to 800s. Analysis and modeling of the results indicate efficient deep trapping of radiation-generated holes in the bulk of the oxide, substantial initial trapping of radiation-generated electrons in the oxide, and rapid removal of the trapped electrons by a thermal detrapping process. The ZMR FETs showed evidence of substantial trapping of holes alone in the oxide bulk

Enhancement of carboxylic acid degradation with sulfate radical generated by persulfate activation.

Science.gov (United States)

Criquet, J; Nebout, P; Karpel Vel Leitner, N

2010-01-01

The aim of this work was to investigate the generation of sulfate radical for the removal of two carboxylic acids in aqueous solution: acetic and citric acids. From photochemical and radiolytic processes, kinetics of the degradation of these two carboxylic acids was studied as a function of the pH of the solution. It was shown that the maximum of acetic acid degradation occurred at pH 5. Above this pH, competitive reactions with the carbon mineralized inhibit the reaction of with the solute. In the case of citric acid, pH has only a little effect on the kinetic of citric acid degradation. The determination of mineralization yields shows several differences depending on carboxylic acids and pH. The degradation of both carboxylic acids was also studied in the radiolysis process whether with or without persulfate addition. A comparison of the processes of sulfate radical production is presented.

Removal of p-Nitrophenol Using Persulfate Activated by Biochars Prepared from Different Biomass Materials

Institute of Scientific and Technical Information of China (English)

SHI Chenfei; LI Yumeng; FENG Haiyao; JIA Shumin; XUE Ruijie; LI Gang; WANG Guoxiang

2018-01-01

Three biochars from wheat straw(WSC),chicken manure(CMC) and rice husk(RHC) were prepared as persulfate(PS) activators for p-nitropheol(PNP) removal.RHC exhibitted the best adsorption performance,followed by WSC and CMC,which was consistant with the surface area value.PS addition further promoted the PNP removal,indicating that a synergistic effect existed in the biochar/PS combined system.The composition and textual properties of biochar had a significant effect on the reactivity of activator and the function groups containing oxgygen or nitrogen might play important roles in the reaction.WSC could perform efficiently over a pH range from 4.4 to 10.4.The decrease in activation performance in cycle experiments was possiblely related to the loss of oxgygen-containing groups.

Light-Enhanced Antibacterial Activity of Graphene Oxide, Mainly via Accelerated Electron Transfer.

Science.gov (United States)

Chong, Yu; Ge, Cuicui; Fang, Ge; Wu, Renfei; Zhang, He; Chai, Zhifang; Chen, Chunying; Yin, Jun-Jie

2017-09-05

Before graphene derivatives can be exploited as next-generation antimicrobials, we must understand their behavior under environmental conditions. Here, we demonstrate how exposure to simulated sunlight significantly enhances the antibacterial activity of graphene oxide (GO) and reveal the underlying mechanism. Our measurements of reactive oxygen species (ROS) showed that only singlet oxygen ( 1 O 2 ) is generated by GO exposed to simulated sunlight, which contributes only slightly to the oxidation of antioxidant biomolecules. Unexpectedly, we find the main cause of oxidation is light-induced electron-hole pairs generated on the surface of GO. These light-induced electrons promote the reduction of GO, introducing additional carbon-centered free radicals that may also enhance the antibacterial activities of GO. We conclude that GO-mediated oxidative stress mainly is ROS-independent; simulated sunlight accelerates the transfer of electrons from antioxidant biomolecules to GO, thereby destroying bacterial antioxidant systems and causing the reduction of GO. Our insights will help support the development of graphene for antibacterial applications.

Preparation of polyaniline/graphene oxide nanocomposite for the application of supercapacitor

International Nuclear Information System (INIS)

Gui, Dayong; Liu, Chunliang; Chen, Fengying; Liu, Jianhong

2014-01-01

Graphene oxide was synthesized by an improved Hummers method. Three polyaniline (PANI)/graphene oxide (GO) nanocomposite electrode materials were prepared from aniline (ANI), GO, and ammonium persulfate (APS) by chemical polymerization with the mass ratio (m ANI :m GO ) 1000:1, 100:1, and 10:1 in ice water, respectively. The crystal structure and the surface topography of all materials were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR) and scanning electron microscopy (SEM). The electrochemical properties of the composite were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and the impedance spectroscope, respectively. The test results show that the composites have similar and enhanced cyclic voltammetry performance compared with pure PANI based electrode material. The PANI/GO composite synthesized with the mass ratio (m ANI :m GO ) 1000:1 possessed excellent capacitive behavior with a specific capacitance as high as 355.2 F g −1 at 0.5 A g −1 in 1 mol L −1 H 2 SO 4 electrolyte due to the unique morphology of Mace-like PANI/GO composite, and after 1000 cycles, the specific capacitance of the composite still has 285.8 F g −1 . These results demonstrate exciting potentials of the composite for high performance supercapacitors or other power source system.

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells.

Science.gov (United States)

Trost, S; Becker, T; Zilberberg, K; Behrendt, A; Polywka, A; Heiderhoff, R; Görrn, P; Riedl, T

2015-01-16

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

In Situ Treatment Train for Remediation of Perfluoroalkyl Contaminated Groundwater: In Situ Chemical Oxidation of Sorbed Contaminants (ISCO SC)

Science.gov (United States)

2017-07-18

viable. Enzymes are employed in natural and engineered systems to overcome reaction energy barriers and thus may be a promising solution. For... Chemical and Engineering Data, 52(4), 1165–1170. http://doi.org/10.1021/je060285g Johnson, R. L., Tratnyek, P. G., & Johnson, R. O. B. (2008...persulfates by carbon nanotubes: Oxidation of organic compounds by nonradical mechanism. Chemical Engineering Journal, 266, 28–33. http://doi.org/10.1016

Oxidation under electron bombardment. A tool for studying the initial states of silicon oxidation

Energy Technology Data Exchange (ETDEWEB)

Carriere, B.; Deville, J.P.; El Maachi, A.

1987-06-01

The exciting beam of an Auger electron spectrometer has been used to monitor the oxidation of silicon single crystals at room temperature and very low pressures of oxygen (approx. 10/sup -7/ Torr). This process allows us to build ultra-thin layers of silica on silicon (down to 30 A) but it is mostly used to investigate the mechanisms of the initial stages of oxidation. Auger spectra recorded continuously during the oxidation process provide information on (1) the nature of the silicon-oxygen chemical bonds which are interpreted through fine structure in the Auger peak, and (2) the kinetics of oxide formation which are deduced from curves of Auger signal versus time. An account is given of the contribution of these Auger studies to the description of the intermediate oxide layer during the reaction between silicon and oxygen and the influence of surface structural disorder, induced mainly by argon-ion bombardment, is discussed in terms of reactivity and oxide coverage.

A Derivative Method with Free Radical Oxidation to Predict Resveratrol Metabolites by Tandem Mass Spectrometry.

Science.gov (United States)

Liu, Wangta; Shiue, Yow-Ling; Lin, Yi-Reng; Lin, Hugo You-Hsien; Liang, Shih-Shin

2015-10-01

In this study, we demonstrated an oxidative method with free radical to generate 3,5,4'-trihydroxy- trans -stilbene ( trans -resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4'-dihydroxy- trans -stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI-MS/MS can be utilized to evaluate different metabolites in various conditions.

Electrodes as Terminal Electron Acceptors in Anaerobic Ammonium Oxidation

Science.gov (United States)

Ruiz-Urigüen, M.; Jaffe, P. R.

2017-12-01

Anaerobic ammonium (NH4+) oxidation under iron (Fe) reducing conditions is a microbial- mediated process known as Feammox. This is a novel pathway in the nitrogen cycle, and a key process for alleviating NH4+ accumulation in anoxic soils, wetlands, and wastewater. Acidimicrobiaceae-bacterium A6, phylum Actinobacteria, are one type of autotrophic bacteria linked to this process. The Feammox-bacteria obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, iron oxides are the TEAs. However, in this study we show that electrodes in Microbial Electrolysis Cells (MECs) or electrodes set in the field can be used as TEAs by Feammox-bacteria. The potential difference between electrodes is the driving force for electron transfer, making the reaction energetically feasible. Our results show that MECs containing Feammox cultures can remove NH4+ up to 3.5 mg/L in less than 4 hours, compared to an average of 9 mg/L in 2 weeks when cultured under traditional conditions. Concomitantly, MECs produce an average current of 30.5 A/m3 whilst dead bacteria produced low (Actinobacteria when compared to bulk soil. Electrodes as TEAs enhance electrogenic bacteria recovery and culturing. The use of MECs for the productions of Feammox-bacteria eliminates the dependence of Fe, a finite electron acceptor, therefore, allowing for continuous NH4+ removal. Finally, Fe-free Feammox-bacteria can be applied to reduce other metals of environmental concern; therefore, opening the range of possible application of Feammox-bacteria.

In situ Reduction and Oxidation of Nickel from Solid Oxide Fuel Cells in a Transmission Electron Microscope

DEFF Research Database (Denmark)

Faes, Antonin; Jeangros, Quentin; Wagner, Jakob Birkedal

2009-01-01

Environmental transmission electron microscopy was used to characterize in situ the reduction and oxidation of nickel from a Ni/YSZ solid oxide fuel cell anode support between 300-500{degree sign}C. The reduction is done under low hydrogen pressure. The reduction initiates at the NiO/YSZ interface...

Electron molecular beam epitaxy: Layer-by-layer growth of complex oxides via pulsed electron-beam deposition

International Nuclear Information System (INIS)

Comes, Ryan; Liu Hongxue; Lu Jiwei; Gu, Man; Khokhlov, Mikhail; Wolf, Stuart A.

2013-01-01

Complex oxide epitaxial film growth is a rich and exciting field, owing to the wide variety of physical properties present in oxides. These properties include ferroelectricity, ferromagnetism, spin-polarization, and a variety of other correlated phenomena. Traditionally, high quality epitaxial oxide films have been grown via oxide molecular beam epitaxy or pulsed laser deposition. Here, we present the growth of high quality epitaxial films using an alternative approach, the pulsed electron-beam deposition technique. We demonstrate all three epitaxial growth modes in different oxide systems: Frank-van der Merwe (layer-by-layer); Stranski-Krastanov (layer-then-island); and Volmer-Weber (island). Analysis of film quality and morphology is presented and techniques to optimize the morphology of films are discussed.

Electronic structure and ionicity of actinide oxides from first principles

DEFF Research Database (Denmark)

Petit, Leon; Svane, Axel; Szotek, Z.

2010-01-01

The ground-state electronic structures of the actinide oxides AO, A2O3, and AO2 (A=U, Np, Pu, Am, Cm, Bk, and Cf) are determined from first-principles calculations, using the self-interaction corrected local spin-density approximation. Emphasis is put on the degree of f-electron localization, whi...

Two-electron electrochemical oxidation of quercetin and kaempferol changes only the flavonoid C-ring

DEFF Research Database (Denmark)

Jørgensen, Lars; Cornett, Claus; Justesen, Ulla

1998-01-01

Bulk electrolysis of the antioxidant flavonoids quercetin and kaempferol in acetonitrile both yield a single oxidation product in two-electron processes. The oxidation products are more polar than their parent compounds, with an increased molecular weight of 16g/mol, and were identified as 2......-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3 (2H)-benzofuranone and 2-(4-hydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone for quercetin and kaempferol, respectively. Two-electron oxidation of the parent flavonoid is suggested to yield a 3,4-flavandione with unchanged substitution pattern in the A- and B-ring, which...... may rearrange to form the substituted 3(2H)-benzofuranone through the chalcan-trione ring-chain tautomer. The acidity of the 3-OH group is suggested to determine the fate of the flavonoid phenoxyl radical originally formed by one-electron oxidation, as no well-defined oxidation product of luteolin...

Charging effects during focused electron beam induced deposition of silicon oxide

NARCIS (Netherlands)

de Boer, Sanne K.; van Dorp, Willem F.; De Hosson, Jeff Th. M.

2011-01-01

This paper concentrates on focused electron beam induced deposition of silicon oxide. Silicon oxide pillars are written using 2, 4, 6, 8, 10-pentamethyl-cyclopenta-siloxane (PMCPS) as precursor. It is observed that branching of the pillar occurs above a minimum pillar height. The branching is

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution.

Science.gov (United States)

Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A; Anthopoulos, Thomas D

2017-03-01

Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In 2 O 3 /ZnO heterojunction. We find that In 2 O 3 /ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In 2 O 3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In 2 O 3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

KAUST Repository

Faber, Hendrik

2017-04-28

Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

Engineering Interfacial Energetics: A Novel Hybrid System of Metal Oxide Quantum Dots and Cobalt Complex for Photocatalytic Water Oxidation

International Nuclear Information System (INIS)

Niu, Fujun; Shen, Shaohua; Wang, Jian; Guo, Liejin

2016-01-01

Graphical abstract: A cobalt complex engineers the interfacial energetics of metal oxide quantum dots (n- or p-type) and electrolytes for highly efficient O_2 generation under visible light irradiation. - Highlights: • A noble-metal-free hybrid photocatalytic system using a single-site cobalt catalyst was developed for O_2 generation. • Considerable activity and excellent stability for O_2 production were achieved by this novel system. • CoSlp engineered the QDs/electrolyte interfacical energetics for efficient hole transfer. - Abstract: Here we reported a novel hybrid photocatalytic water oxidation system, containing metal oxide (n-Fe_2O_3 or p-Co_3O_4) quantum dots (QDs) as light harvester, a salophen cobalt(II) complex (CoSlp) as redox catalyst and persulfate (S_2O_8"2"−) as sacrificial electron acceptor, for oxygen generation from fully aqueous solution. The n-Fe_2O_3 QDs/CoSlp and p-Co_3O_4 QDs/CoSlp systems exhibited good O_2 evolution performances, giving turnover numbers (TONs) of ca. 33 and ca. 35 over CoSlp after visible light irradiation for 72 h, respectively. The excellent photocatalytic performance could be ascribed to the efficient hole transfer from QDs to CoSlp catalyst, leading to reduced photogenerated charge recombination, as well as the CoSlp engineered interfacial band bending of QDs, increasing the driving force or decreasing the energy barrier for hole transfer and then benefiting the following O_2 generation at the QDs/electrolyte interface. The present work successfully demonstrated a novel hybrid system for photocatalytic O_2 evolution from fully aqueous solution; and the essential role of cobalt complexes in engineering the interfacial energetics of semiconductors (n- or p-type) and electrolytes could be informative for designing efficient systems for solar water splitting.

Highly active bidirectional electron transfer by a self-assembled electroactive reduced-graphene-oxide-hybridized biofilm.

Science.gov (United States)

Yong, Yang-Chun; Yu, Yang-Yang; Zhang, Xinhai; Song, Hao

2014-04-22

Low extracellular electron transfer performance is often a bottleneck in developing high-performance bioelectrochemical systems. Herein, we show that the self-assembly of graphene oxide and Shewanella oneidensis MR-1 formed an electroactive, reduced-graphene-oxide-hybridized, three-dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact-based extracellular electron transfer. This 3D electroactive biofilm delivered a 25-fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74-fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermally activated persulfate oxidation regeneration of NOM- and MTBE- spent granular activated carbon

Science.gov (United States)

Chemical oxidation is a developing technology used to regenerate contaminant-spent GAC. Chemical regeneration of GAC represents a viable option to thermal regeneration methods that are energy intensive resulting in significant consumption of fossil fuels and production of greenho...

The Feasibility Study of Persulfate Oxidation to Regenerating of Spent Granular Activated Carbon

Science.gov (United States)

Chemical oxidation is a developing technology used to regenerate contaminant-spent GAC. Chemical regeneration of GAC represents a viable option to thermal regeneration methods that are energy intensive resulting in significant consumption of fossil fuels and production of greenho...

Electrochemically oxidized electronic and ionic conducting nanostructured block copolymers for lithium battery electrodes.

Science.gov (United States)

Patel, Shrayesh N; Javier, Anna E; Balsara, Nitash P

2013-07-23

Block copolymers that can simultaneously conduct electronic and ionic charges on the nanometer length scale can serve as innovative conductive binder material for solid-state battery electrodes. The purpose of this work is to study the electronic charge transport of poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-PEO) copolymers electrochemically oxidized with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt in the context of a lithium battery charge/discharge cycle. We use a solid-state three-terminal electrochemical cell that enables simultaneous conductivity measurements and control over electrochemical doping of P3HT. At low oxidation levels (ratio of moles of electrons removed to moles of 3-hexylthiophene moieties in the electrode), the electronic conductivity (σe,ox) increases from 10(-7) S/cm to 10(-4) S/cm. At high oxidation levels, σe,ox approaches 10(-2) S/cm. When P3HT-PEO is used as a conductive binder in a positive electrode with LiFePO4 active material, P3HT is electrochemically active within the voltage window of a charge/discharge cycle. The electronic conductivity of the P3HT-PEO binder is in the 10(-4) to 10(-2) S/cm range over most of the potential window of the charge/discharge cycle. This allows for efficient electronic conduction, and observed charge/discharge capacities approach the theoretical limit of LiFePO4. However, at the end of the discharge cycle, the electronic conductivity decreases sharply to 10(-7) S/cm, which means the "conductive" binder is now electronically insulating. The ability of our conductive binder to switch between electronically conducting and insulating states in the positive electrode provides an unprecedented route for automatic overdischarge protection in rechargeable batteries.

An internal report: Electron Spectroscopy of the Oxidation and Aging of U and Pu

Energy Technology Data Exchange (ETDEWEB)

Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-04-27

Uranium and Plutonium are highly reactive elements that undergo not only chemical reactions but also nuclear reactions. This can lead to possibly significant materials degradation, a matter of potentially great concern. Here, the issue of the electronic structure changes that occur with oxidation and radiological aging will be addressed, in a fairly empirical manner. In essence, the sensitivity of various electron spectroscopic techniques to oxidation and aging will be surveyed and discussed, including the apparent limitations. It will be found that 5d and 4d X-ray absorption and electron energy loss are essentially blind to the changes corresponding to oxidation and aging in U and Pu.

Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

Science.gov (United States)

Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

2017-12-01

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.

Characterization of Li-rich layered oxides by using transmission electron microscope

Directory of Open Access Journals (Sweden)

Hu Zhao

2017-07-01

Full Text Available Lithium-rich layered oxides (LrLOs deliver extremely high specific capacities and are considered to be promising candidates for electric vehicle and smart grid applications. However, the application of LrLOs needs further understanding of the structural complexity and dynamic evolution of monoclinic and rhombohedral phases, in order to overcome the issues including voltage decay, poor rate capability, initial irreversible capacity loss and etc. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, have fueled rapid progress in the understanding of the mechanism of such issues. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, migration of transition metal, and the activation of oxygen of LrLOs are then explored in detail, with a particular focus on the mechanism of voltage decay. Keywords: Lithium-ion battery, Transmission electron microscope, Lithium-rich layered oxide, Cathode material

The oxidation kinetics for sublimates formed during niobium electron-beam remelting

International Nuclear Information System (INIS)

Chumarev, V.M.; Gulyaeva, R.I.; Mar'evich, V.P.; Upolovnikova, A.G.; Udoeva, L.Yu.

2003-01-01

The oxidation of sublimates of Nb-Al electron beam remelting is investigated under conditions of isothermal and continuous heating in the air. It is stated that basic oxidation products are niobium and aluminium oxides, as well as aluminium niobates of variable composition of Al 2 O 3 · mNb 2 O 5 . The more aluminium enriched sublimates possess an increased resistance to oxidation. Formed in sublimates NbAl 3 intermetallic compound features the highest heat resistance. Oxidation parameters are determined by the method of nonisothermic kinetics. It is noted that the running processes exhibit a multistage nature and are limited by internal diffusion [ru

Formation of quinones by one-electron oxidation in the metabolism of benzo[a]pyrene and 6-fluorobenzo[a]pyrene

International Nuclear Information System (INIS)

Cavalieri, E.; Wong, A.; Cremonesi, P.; Warner, C.; Rogan, E.

1986-01-01

Metabolic activation of polycyclic aromatic hydrocarbons (PAH), as well as other chemical carcinogens, occurs by two major pathways: One-electron oxidation and two-electron oxidation, or monooxygenation. One-electron oxidation generates radical cations or radicals, depending on the molecule in which the oxidation occurs, whereas two-electron oxidation produces oxygenated metabolites. Radical cations of PAH are ultimate electrophilic metabolites capable of binding to cellular macromolecules to initiate the tumor process. In this paper the authors will provide evidence that one-electron oxidation is involved not only in PAH carcinogenesis, but also in the formation of certain metabolites. Metabolism of benzo[a]pyrene (BP) by cytochrome P-450 monooxygenase yields three classes of products: phenols, dihydrodiols and the quinones, 1,6-, 3,6- and 6,12- dione

Artificial electron acceptors decouple archaeal methane oxidation from sulfate reduction.

Science.gov (United States)

Scheller, Silvan; Yu, Hang; Chadwick, Grayson L; McGlynn, Shawn E; Orphan, Victoria J

2016-02-12

The oxidation of methane with sulfate is an important microbial metabolism in the global carbon cycle. In marine methane seeps, this process is mediated by consortia of anaerobic methanotrophic archaea (ANME) that live in syntrophy with sulfate-reducing bacteria (SRB). The underlying interdependencies within this uncultured symbiotic partnership are poorly understood. We used a combination of rate measurements and single-cell stable isotope probing to demonstrate that ANME in deep-sea sediments can be catabolically and anabolically decoupled from their syntrophic SRB partners using soluble artificial oxidants. The ANME still sustain high rates of methane oxidation in the absence of sulfate as the terminal oxidant, lending support to the hypothesis that interspecies extracellular electron transfer is the syntrophic mechanism for the anaerobic oxidation of methane. Copyright © 2016, American Association for the Advancement of Science.

Highly n-Type Titanium Oxide as an Electronically Active Support for Platinum in the Catalytic Oxidation of Carbon Monoxide

KAUST Repository

Baker, L. Robert; Hervier, Antoine; Seo, Hyungtak; Kennedy, Griffin; Komvopoulos, Kyriakos; Somorjai, Gabor A.

2011-01-01

-support interaction is electronic activation of surface adsorbates by charge carriers. Motivated by the goal of using electronic activation to drive nonthermal chemistry, we investigated the ability of the oxide support to mediate charge transfer. We report

Changing of the electron structure of dispersed iron oxide during interaction with amines and borofluoride

International Nuclear Information System (INIS)

Hobert, H.; Arnold, D.

1975-01-01

The mechanism of chemisorption on the surface of iron oxide was studied by Moessbauer spectroscopy performed on samples of iron oxide finely dispersed in SiO 2 . It was found from Moessbauer spectra that the interaction of the oxide with amines resulted in a reversible electron transition from the amine to the adsorbent. The interaction with BF 3 brought about an irreversible electron transition from iron to boron. (A.K.)

Secondary electron emission influenced by oxidation on the aluminum surface: the roles of the chemisorbed oxygen and the oxide layer

Science.gov (United States)

Li, Jiangtao; Hoekstra, Bart; Wang, Zhen-Bin; Qiu, Jie; Pu, Yi-Kang

2018-04-01

A relationship between the apparent secondary electron yield ({γ }{{se}}) and the oxygen coverage/oxide layer thickness on an aluminum cathode is obtained in an experiment under a controlled environment. The apparent secondary electron yield ({γ }{{se}}) is deduced from the breakdown voltage between two parallel plate electrodes in a 360 mTorr argon environment using a simple Townsend breakdown model with the assumption that the variation of the apparent secondary electron yield is dominated by the variation of the argon ion induced processes. The oxygen coverage/oxide layer thickness on the aluminum cathode is measured by a semi in situ x-ray photoemission spectroscopy equipment which is directly attached to the discharge chamber. It is found that three phases exist: (1) in the monomonolayer regime, as the oxygen coverage increases from 0 to 0.3, {γ }{{se}} decreases by nearly 40 % , (2) as the oxygen coverage increases from 0.3 to 1, {γ }{{se}} keeps nearly constant, (3) as the oxide layer thickness increases from about 0.3 nm to about 1.1 nm, {γ }{{se}} increases by 150 % . We propose that, in the submonolayer regime, the chemisorbed oxygen on the aluminum surface causes the decrease of {γ }{{se}} by creating a local potential barrier, which reduces the Auger neutralization rate and the energy gained by the Auger electrons. In the multilayer regime, as the oxide layer grows in thickness, there are three proposed mechanisms which cause the increase of {γ }{{se}}: (1) the work function decreases; (2) resonance neutralization and Auger de-excitation may exist. This is served as another channel for secondary electron production; (3) the kinetic energy of Auger electrons is increased on average, leading to a higher probability for electrons to overcome the surface potential barrier.

Novel High-Viscosity Polyacrylamidated Chitosan for Neural Tissue Engineering: Fabrication of Anisotropic Neurodurable Scaffold via Molecular Disposition of Persulfate-Mediated Polymer Slicing and Complexation

Directory of Open Access Journals (Sweden)

Viness Pillay

2012-10-01

Full Text Available Macroporous polyacrylamide-grafted-chitosan scaffolds for neural tissue engineering were fabricated with varied synthetic and viscosity profiles. A novel approach and mechanism was utilized for polyacrylamide grafting onto chitosan using potassium persulfate (KPS mediated degradation of both polymers under a thermally controlled environment. Commercially available high molecular mass polyacrylamide was used instead of the acrylamide monomer for graft copolymerization. This grafting strategy yielded an enhanced grafting efficiency (GE = 92%, grafting ratio (GR = 263%, intrinsic viscosity (IV = 5.231 dL/g and viscometric average molecular mass (MW = 1.63 × 106 Da compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 106 Da. Image processing analysis of SEM images of the newly grafted neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the characterization and comparison of the newly grafted copolymers. Static Lattice Atomistic Simulations were employed to investigate and elucidate the copolymeric assembly and reaction mechanism by exploring the spatial disposition of chitosan and polyacrylamide with respect to the reactional profile of potassium persulfate. Interestingly, potassium persulfate, a peroxide, was found to play a dual role initially degrading the polymers—“polymer slicing”—thereby initiating the formation of free radicals and subsequently leading to synthesis of the high molecular mass polyacrylamide-grafted-chitosan (PAAm-g-CHT—“polymer complexation”. Furthermore, the applicability of the uniquely grafted scaffold for neural tissue engineering was evaluated via PC12 neuronal cell seeding. The novel PAAm-g-CHT exhibited superior neurocompatibility in terms of cell infiltration owing to the anisotropic porous architecture, high molecular mass mediated robustness

A first principles investigation of the electronic structure of actinide oxides

DEFF Research Database (Denmark)

Petit, Leon; Svane, Axel; Szotek, Zdzislawa

2010-01-01

The ground state electronic structures of the actinide oxides AO, A2O3 and AO2 (A=U, Np, Pu, Am, Cm, Bk, Cf) are determined from first-principles calculations using the selfinteraction corrected local spin-density approximation. Our study reveals a strong link between preferred oxidation number...... and degree of localization. The ionic nature of the actinide oxides emerges from the fact that those oxides where the ground state is calculated to be metallic do not exist in nature, as the corresponding delocalized f-states favour the accommodation of additional O atoms into the crystal lattice....

Electronic properties of thermally formed thin iron oxide films

International Nuclear Information System (INIS)

Wielant, J.; Goossens, V.; Hausbrand, R.; Terryn, H.

2007-01-01

The oxide layer, present between an organic coating and the substrate, guarantees adhesion of the coating and plays a determinating role in the delamination rate of the organic coating. The purpose of this study is to compare the resistive and semiconducting properties of thermal oxides formed on steel in two different atmospheres at 250 deg. C: an oxygen rich atmosphere, air, and an oxygen deficient atmosphere, N 2 . In N 2 , a magnetite layer grows while in air a duplex oxide film forms composed by an inner magnetite layer and a thin outer hematite scale. The heat treatment for different amounts of time at high temperature was used as method to sample the thickness variation and change in electronic and semiconducting properties of the thermal oxide layers. Firstly, linear voltammetric measurements were performed to have a first insight in the electrochemical behavior of the thermal oxides in a borate buffer solution. Electrochemical impedance spectroscopy in the same buffer combined with the Mott-Schottky analysis were used to determine the semiconducting properties of the thermal oxides. By spectroscopic ellipsometry (SE) and atomic force microscopy (AFM), respectively, the thickness and roughness of the oxide layers were determined supporting the physical interpretation of the voltammetric and EIS data. These measurements clearly showed that oxide layers with different constitution, oxide resistance, flatband potential and doping concentration can be grown by changing the atmosphere

FAD oxidizes the ERO1-PDI electron transfer chain: The role of membrane integrity

International Nuclear Information System (INIS)

Papp, Eszter; Nardai, Gabor; Mandl, Jozsef; Banhegyi, Gabor; Csermely, Peter

2005-01-01

The molecular steps of the electron transfer in the endoplasmic reticulum from the secreted proteins during their oxidation are relatively unknown. We present here that flavine adenine dinucleotide (FAD) is a powerful oxidizer of the oxidoreductase system, Ero1 and PDI, besides the proteins of rat liver microsomes and HepG2 hepatoma cells. Inhibition of FAD transport hindered the action of FAD. Microsomal membrane integrity was mandatory for all FAD-related oxidation steps downstream of Ero1. The PDI inhibitor bacitracin could inhibit FAD-mediated oxidation of microsomal proteins and PDI, but did not hinder the FAD-driven oxidation of Ero1. Our data demonstrated that Ero1 can utilize FAD as an electron acceptor and that FAD-driven protein oxidation goes through the Ero1-PDI pathway and requires the integrity of the endoplasmic reticulum membrane. Our findings prompt further studies to elucidate the membrane-dependent steps of PDI oxidation and the role of FAD in redox folding

One-electron oxidation of BD84, an ellipticine antitumor derivative

International Nuclear Information System (INIS)

Sekaki, A.; Gardes-Albert, M.; Houee-Levin, C.; Ferradini, C.; Rivalle, C.; Bisagni, E.; Hickel, B.

1991-01-01

The one-electron oxidation of BD84, an ellipticine-related drug, has been studied by pulse radiolysis using OH· radicals as oxidizing agents. In the absence of oxygen, R· radicals are formed. They disappear by recombination. In the presence of oxygen, R· radicals react with O 2 to give peroxy radicals RO 2 ·, which decay by a second-order process. These results are compared to those obtained for other ellipticine derivatives [fr

Electron momentum spectroscopy of the group I and Il metal and oxides

International Nuclear Information System (INIS)

Ford, M.J.; Dorsett, H.E.; Sashin, V.A.; Bolorizadeh, M.A.; Mikajlo, E.A.; Soule de Bas, B.; Nixon, K.L.; Coleman, V.A.

2002-01-01

Full text: The group I and Il metals and oxides are relatively simple condensed phase systems that are easily accessible to theoretical studies. For this reason they have been the subject of a number of studies using a range of theoretical techniques. Calculated electronic band structures have traditionally been compared with optical, X-ray and photo emissions measurements. While these techniques provide excellent data for testing theoretical predictions they generally probe certain aspects of the electronic structure, such as special point energies or densities of states, or require considerable theoretical input for their interpretation. In this paper we present our electron momentum spectroscopy (EMS) measurements for the lighter group Il metals and oxides and group I oxides. EMS can measure directly the full band dispersions and intensities and provides a sensitive test of theoretical predictions. We compare our measurements with Hartree-Fock (HF) and density functional theory (DFT) calculations carried out within the linear combination of atomic orbitals approximation. As expected HF significantly overestimates the bandwidths and bandgaps. DFT gives reasonable overall agreement, albeit with slight overestimation of bandwidths for the oxides. The intensity distribution for the oxides show a systematic difference from all the calculations which cannot easily be explained by experimental effects such as multiple scattering in the target. This work was funded by the Australian Research Council and Flinders University. EA Mikajlo and K L Nixon acknowledge receipt of SENRAC and Ferry scholarships respectively

Mechanisms for Electron Transfer Through Pili to Fe(III) Oxide in Geobacter

Energy Technology Data Exchange (ETDEWEB)

Lovley, Derek R. [Univ. of Massachusetts, Amherst, MA (United States)

2015-03-09

The purpose of these studies was to aid the Department of Energy in its goal of understanding how microorganisms involved in the bioremediation of metals and radionuclides sustain their activity in the subsurface. This information is required in order to incorporate biological processes into decision making for environmental remediation and long-term stewardship of contaminated sites. The proposed research was designed to elucidate the mechanisms for electron transfer to Fe(III) oxides in Geobacter species because Geobacter species are abundant dissimilatory metal-reducing microorganisms in a diversity of sites in which uranium is undergoing natural attenuation via the reduction of soluble U(VI) to insoluble U(IV) or when this process is artificially stimulated with the addition of organic electron donors. This study investigated the novel, but highly controversial, concept that the final conduit for electron transfer to Fe(III) oxides are electrically conductive pili. The specific objectives were to: 1) further evaluate the conductivity along the pili of Geobacter sulfurreducens and related organisms; 2) determine the mechanisms for pili conductivity; and 3) investigate the role of pili in Fe(III) oxide reduction. The studies demonstrated that the pili of G. sulfurreducens are conductive along their length. Surprisingly, the pili possess a metallic-like conductivity similar to that observed in synthetic organic conducting polymers such as polyaniline. Detailed physical analysis of the pili, as well as studies in which the structure of the pili was genetically modified, demonstrated that the metallic-like conductivity of the pili could be attributed to overlapping pi-pi orbitals of aromatic amino acids. Other potential mechanisms for conductivity, such as electron hopping between cytochromes associated with the pili were definitively ruled out. Pili were also found to be essential for Fe(III) oxide reduction in G. metallireducens. Ecological studies demonstrated

Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater

International Nuclear Information System (INIS)

Mahdi-Ahmed, Moussa; Chiron, Serge

2014-01-01

Highlights: • UV/PMS more efficient than UV/H 2 O 2 for ciprofloxacin removal in wastewater. • PMS decomposition into sulfate radical was activated by bicarbonate ions. • CIP degradation pathways elucidation support sulfate radical attacks as a main route. • Sulfate radical generation allows for CIP antibacterial activity elimination. -- Abstract: This work aimed at demonstrating the advantages to use sulfate radical anion for eliminating ciprofloxacin residues from treated domestic wastewater by comparing three UV-254 nm based advanced oxidation processes: UV/persulfate (PDS), UV/peroxymonosulfate (PMS) and UV/H 2 O 2 . In distilled water, the order of efficiency was UV/PDS > UV/PMS > UV/H 2 O 2 while in wastewater, the most efficient process was UV/PMS followed by UV/PDS and UV/H 2 O 2 mainly because PMS decomposition into sulfate radical anion was activated by bicarbonate ions. CIP was fully degraded in wastewater at pH 7 in 60 min for a [PMS]/[CIP] molar ratio of 20. Nine transformation products were identified by liquid chromatography–high resolution-mass spectrometry allowing for the establishment of degradation pathways in the UV/PMS system. Sulfate radical anion attacks prompted transformations at the piperazinyl ring through a one electron oxidation mechanism as a major pathway while hydroxyl radical attacks were mainly responsible for quinolone moiety transformations as a minor pathway. Sulfate radical anion generation has made UV/PMS a kinetically effective process in removing ciprofloxacin from wastewater with the elimination of ciprofloxacin antibacterial activity

Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater

Energy Technology Data Exchange (ETDEWEB)

Mahdi-Ahmed, Moussa; Chiron, Serge, E-mail: Serge.Chiron@msem.univ-montp2.fr

2014-01-30

Highlights: • UV/PMS more efficient than UV/H{sub 2}O{sub 2} for ciprofloxacin removal in wastewater. • PMS decomposition into sulfate radical was activated by bicarbonate ions. • CIP degradation pathways elucidation support sulfate radical attacks as a main route. • Sulfate radical generation allows for CIP antibacterial activity elimination. -- Abstract: This work aimed at demonstrating the advantages to use sulfate radical anion for eliminating ciprofloxacin residues from treated domestic wastewater by comparing three UV-254 nm based advanced oxidation processes: UV/persulfate (PDS), UV/peroxymonosulfate (PMS) and UV/H{sub 2}O{sub 2}. In distilled water, the order of efficiency was UV/PDS > UV/PMS > UV/H{sub 2}O{sub 2} while in wastewater, the most efficient process was UV/PMS followed by UV/PDS and UV/H{sub 2}O{sub 2} mainly because PMS decomposition into sulfate radical anion was activated by bicarbonate ions. CIP was fully degraded in wastewater at pH 7 in 60 min for a [PMS]/[CIP] molar ratio of 20. Nine transformation products were identified by liquid chromatography–high resolution-mass spectrometry allowing for the establishment of degradation pathways in the UV/PMS system. Sulfate radical anion attacks prompted transformations at the piperazinyl ring through a one electron oxidation mechanism as a major pathway while hydroxyl radical attacks were mainly responsible for quinolone moiety transformations as a minor pathway. Sulfate radical anion generation has made UV/PMS a kinetically effective process in removing ciprofloxacin from wastewater with the elimination of ciprofloxacin antibacterial activity.

Pseudo-diode based on protonic/electronic hybrid oxide transistor

Science.gov (United States)

Fu, Yang Ming; Liu, Yang Hui; Zhu, Li Qiang; Xiao, Hui; Song, An Ran

2018-01-01

Current rectification behavior has been proved to be essential in modern electronics. Here, a pseudo-diode is proposed based on protonic/electronic hybrid indium-gallium-zinc oxide electric-double-layer (EDL) transistor. The oxide EDL transistors are fabricated by using phosphorous silicate glass (PSG) based proton conducting electrolyte as gate dielectric. A diode operation mode is established on the transistor, originating from field configurable proton fluxes within the PSG electrolyte. Current rectification ratios have been modulated to values ranged between ˜4 and ˜50 000 with gate electrode biased at voltages ranged between -0.7 V and 0.1 V. Interestingly, the proposed pseudo-diode also exhibits field reconfigurable threshold voltages. When the gate is biased at -0.5 V and 0.3 V, threshold voltages are set to ˜-1.3 V and -0.55 V, respectively. The proposed pseudo-diode may find potential applications in brain-inspired platforms and low-power portable systems.

One-electron oxidation of DNA: mechanism and consequences.

Science.gov (United States)

Schuster, Gary B

2009-01-01

All living organisms store the information necessary to maintain life in their DNA. Any process that damages DNA and causes loss or corruption of that information threatens the viability of the organism. One-electron oxidation is such a process. Loss of an electron from DNA generates a radical cation that is located primarily on its nucleobases. The radical cation migrates reversibly through duplex DNA by hopping until it is eventually trapped in an irreversible chemical reaction. The particular sequence of nucleobases in a DNA oligomer determines both the efficiency of hopping and the specific location and nature of the damaging chemical reaction. In its normal aqueous solutions, DNA is a polyanion because of the negative charge carried by its phosphate groups. Counter ions (typically Na(+)) to the phosphate groups play an important role in facilitating both the migration of the radical cation and in its eventual reaction with H(2)O. Irreversible reaction of a radical cation with H(2)O in duplex DNA occurs preferentially at the most reactive site. In normal DNA that is comprised of the four common DNA nucleobases, reaction occurs most commonly at a guanine and results in its conversion primarily to 8-oxo-7,8-dihydroguanine (8-OxoG). Both electronic and steric effects control the outcome of this process. If the DNA oligomer does not contain a suitable guanine, then reaction of the radical cation occurs at the thymine of a TT step primarily by a tandem process. The general outcomes revealed in the one-electron oxidation of DNA oligomers in solution appear to be generally valid also for more complex DNA structures and for the cellular DNA of living organisms.

Treatment of aqueous wastes contaminated with Congo Red dye by electrochemical oxidation and ozonation processes

International Nuclear Information System (INIS)

Faouzi Elahmadi, Mohammed; Bensalah, Nasr; Gadri, Abdellatif

2009-01-01

Synthetic aqueous wastes polluted with Congo Red (CR) have been treated by two advanced oxidation processes: electrochemical oxidation on boron doped diamond anodes (BDD-EO) and ozonation under alkaline conditions. For same concentrations, galvanostatic electrolyses have led to total COD and TOC removals but ozonation process can reach only 85% and 81% of COD and TOC removals, respectively. UV-vis qualitative analyses have shown different behaviors of CR molecules towards ozonation and electrochemical oxidation. Rapid discoloration has been observed during ozonation, whereas color persistence till the end of galvanostatic electrolyses has been seen during BDD-EO process. It seems that the oxidation mechanisms involved in the two processes are different: simultaneous destruction of azoic groups is suggested during ozonation process but consecutive destruction of these groups is proposed during BDD-EO. However, energetic study has evidenced that BDD-EO appears more efficient and more economic than ozonation in terms of TOC removals. These results have been explained by the fact that during BDD-EO, other strong oxidants electrogenerated from the electrolyte oxidation such as persulfates and direct-oxidation of CR and its byproducts on BDD anodes complement the hydroxyl radicals mediated oxidation to accomplish the total mineralization of organics.

Phosphorene Oxide: Stability and electronic properties of a novel 2D material

OpenAIRE

Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P.

2014-01-01

Phosphorene, the monolayer form of the (black) phosphorus, was recently exfoliated from its bulk counterpart. Phosphorene oxide, by analogy to graphene oxide, is expected to have novel chemical and electronic properties, and may provide an alternative route to synthesis of phosphorene. In this letter, we investigate physical and chemical properties of the phosphorene oxide including its formation by the oxygen adsorption on the bare phosphorene. Analysis of the phonon dispersion curves finds ...

Nitric Oxide Synthases Reveal a Role for Calmodulin in Controlling Electron Transfer

Science.gov (United States)

Abu-Soud, Husam M.; Stuehr, Dennis J.

1993-11-01

Nitric oxide (NO) is synthesized within the immune, vascular, and nervous systems, where it acts as a wide-ranging mediator of mammalian physiology. The NO synthases (EC 1.14.13.39) isolated from neurons or endothelium are calmodulin dependent. Calmodulin binds reversibly to neuronal NO synthase in response to elevated Ca2+, triggering its NO production by an unknown mechanism. Here we show that calmodulin binding allows NADPH-derived electrons to pass onto the heme group of neuronal NO synthase. Calmodulin-triggered electron transfer to heme was independent of substrate binding, caused rapid enzymatic oxidation of NADPH in the presence of O_2, and was required for NO synthesis. An NO synthase isolated from cytokine-induced macrophages that contains tightly bound calmodulin catalyzed spontaneous electron transfer to its heme, consistent with bound calmodulin also enabling electron transfer within this isoform. Together, these results provide a basis for how calmodulin may regulate NO synthesis. The ability of calmodulin to trigger electron transfer within an enzyme is unexpected and represents an additional function for calcium-binding proteins in biology.

Microbial Anaerobic Ammonium Oxidation Under Iron Reducing Conditions, Alternative Electron Acceptors

Science.gov (United States)

Ruiz-Urigüen, M.; Jaffe, P. R.

2015-12-01

Autotrophic Acidimicrobiaceae-bacterium named A6 (A6), part of the Actinobacteria phylum have been linked to anaerobic ammonium (NH4+) oxidation under iron reducing conditions. These organisms obtain their energy by oxidizing NH4+ and transferring the electrons to a terminal electron acceptor (TEA). Under environmental conditions, the TEAs are iron oxides [Fe(III)], which are reduced to Fe(II), this process is known as Feammox. Our studies indicate that alternative forms of TEAs can be used by A6, e.g. iron rich clays (i.e. nontronite) and electrodes in bioelectrochemical systems such as Microbial Electrolysis Cells (MECs), which can sustain NH4+removal and A6 biomass production. Our results show that nontronite can support Feammox and promote bacterial cell production. A6 biomass increased from 4.7 x 104 to 3.9 x 105 cells/ml in 10 days. Incubations of A6 in nontronite resulted in up to 10 times more NH4+ removal and 3 times more biomass production than when ferrihydrite is used as the Fe(III) source. Additionally, Fe in nontronite can be reoxidized by aeration and A6 can reutilize it; however, Fe is still finite in the clay. In contrast, in MECs, A6 harvest electrons from NH4+ and use an anode as an unlimited TEA, as a result current is produced. We operated multiple MECs in parallel using a single external power source, as described by Call & Logan (2011). MECs were run with an applied voltage of 0.7V and different growing mediums always containing initial 5mM NH4+. Results show that current production is favored when anthraquinone-2,6-disulfonate (AQDS), an electron shuttled, is present in the medium as it facilitates the transfer of electrons from the bacterial cell to the anode. Additionally, A6 biomass increased from 1 x 104 to 9.77 x 105cells/ml in 14 days of operation. Due to Acidimicrobiaceae-bacterium A6's ability to use various TEAs, MECs represent an alternative, iron-free form, for optimized biomass production of A6 and its application in NH4

Effects of keV electron irradiation on the avalanche-electron generation rates of three donors on oxidized silicon

International Nuclear Information System (INIS)

Sah, C.; Sun, J.Y.; Tzou, J.J.

1983-01-01

After keV electron beam irradiation of oxidized silicon, the avalanche-electron-injection generation rates and densities of the bulk compensating donor, the interface states, and the turnaround trap all increase. Heating at 200 0 C can anneal out these three donor-like traps, however, it cannot restore the generation rates back to their original and lower pre-keV electron irradiation values. The experimental results also indicate that all three traps may be related to the same mobile impurity species whose bonds are loosened by the keV electrons and then broken or released by the avalanche injected electrons

Characterization of palladium nanoparticles anchored on graphene oxide obtained by electron beam

Energy Technology Data Exchange (ETDEWEB)

Sobrinho, Luiza F.; Garcia, Rafael H.L.; Silva, Flávia R.O.; Neto, Almir O.; Sakata, Solange K., E-mail: lunnaquimica@usp.br, E-mail: sksakata@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

Fuel Cells (FCs) are devices that convert chemical energy directly in electrical and thermal energy. There are two disadvantages in the process that difficult the implementation of these new power supply. The fuel, hydrogen, is highly flammable and it is difficult to transport and the catalyst is costly. FCs have been attracting worldwide attention because they are environmental friendly and potential as clean and efficient power source. However, their durability and cost have being identified as important issues in this power supply. The objective of this work is to provide a new material based on incorporation of palladium graphene oxide as catalyst. Graphene Oxide (GO) was synthesized from graphite by the modified Hummers method, in water/alcohol medium. The one-step method to incorporate nanoparticles on this nanomaterial was developed using by electron beam (EB). Additionally, this method also reduces the Graphene Oxide (GO). This nanocomposite were characterized by thermogravimetry (TG), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), x-rays diffraction (XRD) and its potential for electro catalysis were performed by cyclic voltammetry (CV) and amperometry (CA). The results showed that the incorporation of Pd on reduced GO (rGO) by electron beam was 20-40 % in mass. The process using EB and Pd nanoparticles supported on graphene oxide as a support are an alternative, in substitution of conventional methods to the production of electrodes for fuel cells. (author)

Characterization of palladium nanoparticles anchored on graphene oxide obtained by electron beam

International Nuclear Information System (INIS)

Sobrinho, Luiza F.; Garcia, Rafael H.L.; Silva, Flávia R.O.; Neto, Almir O.; Sakata, Solange K.

2017-01-01

Fuel Cells (FCs) are devices that convert chemical energy directly in electrical and thermal energy. There are two disadvantages in the process that difficult the implementation of these new power supply. The fuel, hydrogen, is highly flammable and it is difficult to transport and the catalyst is costly. FCs have been attracting worldwide attention because they are environmental friendly and potential as clean and efficient power source. However, their durability and cost have being identified as important issues in this power supply. The objective of this work is to provide a new material based on incorporation of palladium graphene oxide as catalyst. Graphene Oxide (GO) was synthesized from graphite by the modified Hummers method, in water/alcohol medium. The one-step method to incorporate nanoparticles on this nanomaterial was developed using by electron beam (EB). Additionally, this method also reduces the Graphene Oxide (GO). This nanocomposite were characterized by thermogravimetry (TG), Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), x-rays diffraction (XRD) and its potential for electro catalysis were performed by cyclic voltammetry (CV) and amperometry (CA). The results showed that the incorporation of Pd on reduced GO (rGO) by electron beam was 20-40 % in mass. The process using EB and Pd nanoparticles supported on graphene oxide as a support are an alternative, in substitution of conventional methods to the production of electrodes for fuel cells. (author)

Transport of electrons in lead oxide studied by CELIV technique

International Nuclear Information System (INIS)

Semeniuk, O; Juska, G; Oelerich, J O; Jandieri, K; Baranovskii, S D; Reznik, A

2017-01-01

Although polycrystalline lead oxide (PbO) has a long history of application in optoelectronics and imaging, the transport mechanism for electrons in this material has not yet been clarified. Using the photo-generated charge extraction by linear increasing voltage (photo-CELIV) technique, we provide the temperature- and field-dependences of electron mobility in poly-PbO. It is found that electrons undergo dispersive transport, i.e. their mobility decreases in the course of time. Multiple trapping of electrons from the conduction band into the developed band tail is revealed as the dominant transport mechanism. This differs dramatically from the dispersive transport of holes in the same material, dominated by topological factors and not by energy disorder. (paper)

Positron annihilation induced Auger electron spectroscopic studies of oxide surfaces

Science.gov (United States)

Nadesalingam, Manori

2005-03-01

Defects on oxide surfaces are well known to play a key role in catalysis. TiO2, MgO, SiO2 surfaces were investigated using Time-Of-Flight Positron induced Auger Electron Spectroscopy (TOF-PAES). Previous work in bulk materials has demonstrated that positrons are particularly sensitive to charged defects. In PAES energetic electron emission results from Auger transitions initiated by annihilation of core electrons with positrons trapped in an image-potential well at the surface. Annealed samples in O2 environment show a strong Auger peak of Oxygen. The implication of these results will be discussed

Average electronegativity, electronic polarizability and optical basicity of lanthanide oxides for different coordination numbers

International Nuclear Information System (INIS)

Zhao Xinyu; Wang Xiaoli; Lin Hai; Wang Zhiqiang

2008-01-01

On the basis of new electronegativity values, electronic polarizability and optical basicity of lanthanide oxides are calculated from the concept of average electronegativity given by Asokamani and Manjula. The estimated values are in close agreement with our previous conclusion. Particularly, we attempt to obtain new data of electronic polarizability and optical basicity of lanthanide sesquioxides for different coordination numbers (6-12). The present investigation suggests that both electronic polarizability and optical basicity increase gradually with increasing coordination number. We also looked for another double peak effect, that is, electronic polarizability and optical basicity of trivalent lanthanide oxides show a gradual decrease and then an abrupt increase at the Europia and Ytterbia. Furthermore, close correlations are investigated among average electronegativity, optical basicity, electronic polarizability and coordination number in this paper

Morphology and electronic structure of the oxide shell on the surface of iron nanoparticles.

Science.gov (United States)

Wang, Chongmin; Baer, Donald R; Amonette, James E; Engelhard, Mark H; Antony, Jiji; Qiang, You

2009-07-01

An iron (Fe) nanoparticle exposed to air at room temperature will be instantly covered by an oxide shell that is typically approximately 3 nm thick. The nature of this native oxide shell, in combination with the underlying Fe(0) core, determines the physical and chemical behavior of the core-shell nanoparticle. One of the challenges of characterizing core-shell nanoparticles is determining the structure of the oxide shell, that is, whether it is FeO, Fe(3)O(4), gamma-Fe(2)O(3), alpha-Fe(2)O(3), or something else. The results of prior characterization efforts, which have mostly used X-ray diffraction and spectroscopy, electron diffraction, and transmission electron microscopic imaging, have been framed in terms of one of the known Fe-oxide structures, although it is not necessarily true that the thin layer of Fe oxide is a known Fe oxide. In this Article, we probe the structure of the oxide shell on Fe nanoparticles using electron energy loss spectroscopy (EELS) at the oxygen (O) K-edge with a spatial resolution of several nanometers (i.e., less than that of an individual particle). We studied two types of representative particles: small particles that are fully oxidized (no Fe(0) core) and larger core-shell particles that possess an Fe core. We found that O K-edge spectra collected for the oxide shell in nanoparticles show distinct differences from those of known Fe oxides. Typically, the prepeak of the spectra collected on both the core-shell and the fully oxidized particles is weaker than that collected on standard Fe(3)O(4). Given the fact that the origin of this prepeak corresponds to the transition of the O 1s electron to the unoccupied state of O 2p hybridized with Fe 3d, a weak pre-edge peak indicates a combination of the following four factors: a higher degree of occupancy of the Fe 3d orbital; a longer Fe-O bond length; a decreased covalency of the Fe-O bond; and a measure of cation vacancies. These results suggest that the coordination configuration in

COMPUTATIONAL ELECTROCHEMISTRY: AQUEOUS ONE-ELECTRON OXIDATION POTENTIALS FOR SUBSTITUTED ANILINES

Science.gov (United States)

Semiempirical molecular orbital theory and density functional theory are used to compute one-electron oxidation potentials for aniline and a set of 21 mono- and di-substituted anilines in aqueous solution. Linear relationships between theoretical predictions and experiment are co...

Oxidation mechanism of nickel particles studied in an environmental transmission electron microscope

DEFF Research Database (Denmark)

Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

2014-01-01

The oxidation of nickel particles was studied in situ in an environmental transmission electron microscope in 3.2 mbar of O2 between ambient temperature and 600°C. Several different transmission electron microscopy imaging techniques, electron diffraction and electron energy-loss spectroscopy were...... diffusion of Ni2+ along NiO grain boundaries, self-diffusion of Ni2+ ions and vacancies, growth of NiO grains and nucleation of voids at Ni/NiO interfaces. We also observed the formation of transverse cracks in a growing NiO film in situ in the electron microscope....

Oxidations of N-(3-indoleethyl) cyclic aliphatic amines by horseradish peroxidase: the indole ring binds to the enzyme and mediates electron-transfer amine oxidation.

Science.gov (United States)

Ling, Ke-Qing; Li, Wen-Shan; Sayre, Lawrence M

2008-01-23

Although oxidations of aromatic amines by horseradish peroxidase (HRP) are well-known, typical aliphatic amines are not substrates of HRP. In this study, the reactions of N-benzyl and N-methyl cyclic amines with HRP were found to be slow, but reactions of N-(3-indoleethyl) cyclic amines were 2-3 orders of magnitude faster. Analyses of pH-rate profiles revealed a dominant contribution to reaction by the amine-free base forms, the only species found to bind to the enzyme. A metabolic study on a family of congeneric N-(3-indoleethyl) cyclic amines indicated competition between amine and indole oxidation pathways. Amine oxidation dominated for the seven- and eight-membered azacycles, where ring size supports the change in hybridization from sp3 to sp2 that occurs upon one-electron amine nitrogen oxidation, whereas only indole oxidation was observed for the six-membered ring congener. Optical difference spectroscopic binding data and computational docking simulations suggest that all the arylalkylamine substrates bind to the enzyme through their aromatic termini with similar binding modes and binding affinities. Kinetic saturation was observed for a particularly soluble substrate, consistent with an obligatory role of an enzyme-substrate complexation preceding electron transfer. The significant rate enhancements seen for the indoleethylamine substrates suggest the ability of the bound indole ring to mediate what amounts to medium long-range electron-transfer oxidation of the tertiary amine center by the HRP oxidants. This is the first systematic investigation to document aliphatic amine oxidation by HRP at rates consistent with normal metabolic turnover, and the demonstration that this is facilitated by an auxiliary electron-rich aromatic ring.

Electrochemical/chemical oxidation of bisphenol A in a four-electron/two-proton process in aprotic organic solvents

International Nuclear Information System (INIS)

Chan, Ya Yun; Yue, Yanni; Li, Yongxin; Webster, Richard D.

2013-01-01

Graphical abstract: - Highlights: • Bisphenol A undergoes a chemically irreversible voltammetric oxidation process. • Chemical oxidation was performed to overcome adsorption effects that cause electrode fouling. • A new product was isolated from chemical oxidation with 4 mol equiv. of the one-electron oxidant, NO + . • The oxidative mechanism was proposed to be a four-electron/two-proton process. - Abstract: The electrochemical behavior of bisphenol A (BPA) was examined using cyclic voltammetry, bulk electrolysis and chemical oxidation in aprotic organic solvents. It was found that BPA undergoes a chemically irreversible voltammetric oxidation process to form compounds that cannot be electrochemically converted back to the starting materials on the voltammetric timescale. To overcome the effects of electrode fouling during controlled potential electrolysis experiments, NO + was used as a one-electron chemical oxidant. A new product, hydroxylated bisdienone was isolated from the chemical oxidation of BPA with 4 mol equiv of NO + SbF 6 − in low water content CH 3 CN. The structure of the cation intermediate species was deduced and it was proposed that BPA is oxidized in a four-electron/two-proton process to form a relatively unstable dication which reacts quickly in the presence of water in acetonitrile (in a mechanism that is similar to phenols in general). However, as the water content of the solvent increased it was found that the chemical oxidation mechanism produced a nitration product in high yield. The findings from this study provide useful insights into the reactions that can occur during oxidative metabolism of BPA and highlight the possibility of the role of a bisdienone cation as a reactive metabolite in biological systems

Treatability studies

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Studds, Phil

developed a mobile test unit including equipment for both standard and more advanced oxidation test directly on the site. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, Fenton’s, permanganate, and persulfate among others. A versatile...

One step electrosynthesis of polyacrylamide crosslinked by reduced graphene oxide and its application in the simultaneous determination of dopamine and uric acid

International Nuclear Information System (INIS)

Yang, Yu Jun

2014-01-01

Polyacrylamide (PAM)/reduced graphene oxide (rGO) nanocomposite (PAM/rGO) with rGO nanosheets as cross-linkers were synthesized via electropolymerizing acrylamide in an aqueous suspension of GO containing sodium nitrate and potassium persulfate. The PAM/rGO was characterized with X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). XRD patterns of the PAM/rGO indicated that rGO was fully exfoliated into individual sheets in the polymer matrix. SEM study exhibits the highly uniform coverage of PAM/rGO membrane on the GCE and its fibrous nanostructure. The electrochemical characteristics of the PAM/rGO modified glassy carbon electrode (GCE) were investigated with cyclic voltammetry (CV), suggesting the extraordinary electrocatalytic effect of PAM/rGO/GCE towards the electro-oxidation of UA and DA. The PAM/rGO/GCE behaved linearly to DA and UA in the concentration range of 3 × 10 −7 to 5 × 10 −5 M and 1 × 10 −6 to 5 × 10 −5 M with a detection limit of 1 × 10 −7 M and 5 × 10 −7 M, respectively. The proposed method was successfully utilized for simultaneous determination of UA and DA in real samples

Molecular Computational Investigation of Electron Transfer Kinetics across Cytochrome-Iron Oxide Interfaces

International Nuclear Information System (INIS)

Kerisit, Sebastien N.; Rosso, Kevin M.; Dupuis, Michel; Valiev, Marat

2007-01-01

The interface between electron transfer proteins such as cytochromes and solid phase mineral oxides is central to the activity of dissimilatory-metal reducing bacteria. A combination of potential-based molecular dynamics simulations and ab initio electronic structure calculations are used in the framework of Marcus' electron transfer theory to compute elementary electron transfer rates from a well-defined cytochrome model, namely the small tetraheme cytochrome (STC) from Shewanella oneidensis, to surfaces of the iron oxide mineral hematite (a-Fe2O3). Room temperature molecular dynamics simulations show that an isolated STC molecule favors surface attachment via direct contact of hemes I and IV at the poles of the elongated axis, with electron transfer distances as small as 9 Angstroms. The cytochrome remains attached to the mineral surface in the presence of water and shows limited surface diffusion at the interface. Ab initio electronic coupling matrix element (VAB) calculations of configurations excised from the molecular dynamics simulations reveal VAB values ranging from 1 to 20 cm-1, consistent with nonadiabaticity. Using these results, together with experimental data on the redox potential of hematite and hemes in relevant cytochromes and calculations of the reorganization energy from cluster models, we estimate the rate of electron transfer across this model interface to range from 1 to 1000 s-1 for the most exothermic driving force considered in this work, and from 0.01 to 20 s-1 for the most endothermic. This fairly large range of electron transfer rates highlights the sensitivity of the rate upon the electronic coupling matrix element, which is in turn dependent on the fluctuations of the heme configuration at the interface. We characterize this dependence using an idealized bis-imidazole heme to compute from first principles the VAB variation due to porphyrin ring orientation, electron transfer distance, and mineral surface termination. The electronic

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

International Nuclear Information System (INIS)

Richard T. Scalettar; Warren E. Pickett

2005-01-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Scalettar, Richard T.; Pickett, Warren E.

2004-07-01

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (1) Mott transitions in transition metal oxides, (2) magnetism in half-metallic compounds, and (3) large volume-collapse transitions in f-band metals.

High-Pressure Thermodynamic Properties of f-electron Metals, Transition Metal Oxides, and Half-Metallic Magnets

Energy Technology Data Exchange (ETDEWEB)

Richard T. Scalettar; Warren E. Pickett

2005-08-02

This project involves research into the thermodynamic properties of f-electron metals, transition metal oxides, and half-metallic magnets at high pressure. These materials are ones in which the changing importance of electron-electron interactions as the distance between atoms is varied can tune the system through phase transitions from localized to delocalized electrons, from screened to unscreened magnetic moments, and from normal metal to one in which only a single spin specie can conduct. Three main thrusts are being pursued: (i) Mott transitions in transition metal oxides, (ii) magnetism in half-metallic compounds, and (iii) large volume-collapse transitions in f-band metals.

Flame retardant cotton fabrics by electron beam-induced polymerization of vinyl phosphonate oligomer

International Nuclear Information System (INIS)

Sawai, Takeshi; Ametani, Kazuo; Enomoto, Ichiro

1988-01-01

Vinyl phosphonate oligomer is presently used commercially as a cellulosic flame retardant in conjugation with N-methylol acrylamide, using a persulfate catalyst and a thermal cure. This combination can also be cured at room temperature with electron beams, as can the vinyl phosphonate alone. For the textile application, fixation of flame retardants by electron beams with low energy is one of the most promising applications. For the purpose of preparing flame resistant cotton fabrics such as bed sheets and pajamas, flame retardant curing of vinyl phosphonate oligomer on cotton fabrics was examined using electron beams from a self-sealed electron beam processor and gamma rays from a 60 Co source. A joint investigation was undertaken by the Tokyo Metropolitan Textile Research Institute and Tokyo Metropolitan Isotope Research Center to determine the feasibility of curing vinyl phosphonate oligomer on the cotton fabrics for textile finishing. (author)

Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping

NARCIS (Netherlands)

Chen, Yunzhong; Trier, F.; Wijnands, Tom; Green, R.J.; Gauquelin, N.; Egoavil, R.; Christensen, D.V.; Koster, Gertjan; Huijben, Mark; Bovet, N.; Macke, S.; He, F.; Sutarto, R.; Andersen, N.H.; Sulpizio, J.A.; Honig, M.; Prawiroatmodjo, G.E.D.K.; Jespersen, T.S.; Linderoth, S.; Ilani, S.; Verbeeck, J.; van Tendeloo, G.; Rijnders, Augustinus J.H.M.; Sawatzky, G.A.; Pryds, N.

2015-01-01

Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable

Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

Directory of Open Access Journals (Sweden)

H. J. Harsan Ma

2015-08-01

Full Text Available The two-dimensional electron gas (2DEG formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO3 (LAO and non-polar SrTiO3 (STO. Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La0.5Sr0.5TiO3 (LSTO layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

Size-dependent single electron transfer and semi-metal-to-insulator transitions in molecular metal oxide electronics

Science.gov (United States)

Balliou, Angelika; Bouroushian, Mirtat; Douvas, Antonios M.; Skoulatakis, George; Kennou, Stella; Glezos, Nikos

2018-07-01

All-inorganic self-arranged molecular transition metal oxide hyperstructures based on polyoxometalate molecules (POMs) are fabricated and tested as electronically tunable components in emerging electronic devices. POM hyperstructures reveal great potential as charging nodes of tunable charging level for molecular memories and as enhancers of interfacial electron/hole injection for photovoltaic stacks. STM, UPS, UV–vis spectroscopy and AFM measurements show that this functionality stems from the films’ ability to structurally tune their HOMO–LUMO levels and electron localization length at room temperature. By adapting POM nanocluster size in solution, self-doping and current modulation of four orders of magnitude is monitored on a single nanocluster on SiO2 at voltages as low as 3 Volt. Structurally driven insulator-to-semi-metal transitions and size-dependent current regulation through single electron tunneling are demonstrated and examined with respect to the stereochemical and electronic structure of the molecular entities. This extends the value of self-assembly as a tool for correlation length and electronic properties tuning and demonstrate POM hyperstructures’ plausibility for on-chip molecular electronics operative at room temperature.

Size-dependent single electron transfer and semi-metal-to-insulator transitions in molecular metal oxide electronics.

Science.gov (United States)

Balliou, Angelika; Bouroushian, Mirtat; Douvas, Antonios M; Skoulatakis, George; Kennou, Stella; Glezos, Nikos

2018-07-06

All-inorganic self-arranged molecular transition metal oxide hyperstructures based on polyoxometalate molecules (POMs) are fabricated and tested as electronically tunable components in emerging electronic devices. POM hyperstructures reveal great potential as charging nodes of tunable charging level for molecular memories and as enhancers of interfacial electron/hole injection for photovoltaic stacks. STM, UPS, UV-vis spectroscopy and AFM measurements show that this functionality stems from the films' ability to structurally tune their HOMO-LUMO levels and electron localization length at room temperature. By adapting POM nanocluster size in solution, self-doping and current modulation of four orders of magnitude is monitored on a single nanocluster on SiO 2 at voltages as low as 3 Volt. Structurally driven insulator-to-semi-metal transitions and size-dependent current regulation through single electron tunneling are demonstrated and examined with respect to the stereochemical and electronic structure of the molecular entities. This extends the value of self-assembly as a tool for correlation length and electronic properties tuning and demonstrate POM hyperstructures' plausibility for on-chip molecular electronics operative at room temperature.

A graphene oxide-carbon nanotube grid for high-resolution transmission electron microscopy of nanomaterials

International Nuclear Information System (INIS)

Zhang Lina; Zhang Haoxu; Zhou Ruifeng; Chen Zhuo; Li Qunqing; Fan Shoushan; Jiang Kaili; Ge Guanglu; Liu Renxiao

2011-01-01

A novel grid for use in transmission electron microscopy is developed. The supporting film of the grid is composed of thin graphene oxide films overlying a super-aligned carbon nanotube network. The composite film combines the advantages of graphene oxide and carbon nanotube networks and has the following properties: it is ultra-thin, it has a large flat and smooth effective supporting area with a homogeneous amorphous appearance, high stability, and good conductivity. The graphene oxide-carbon nanotube grid has a distinct advantage when characterizing the fine structure of a mass of nanomaterials over conventional amorphous carbon grids. Clear high-resolution transmission electron microscopy images of various nanomaterials are obtained easily using the new grids.

Chemistry and electronics of oxides from carbon dioxide to perovskite

International Nuclear Information System (INIS)

Koinuma, Hideomi

2005-01-01

Oxides are thermodynamic stable form of materials in terrestrial conditions to exist as final products of energy consumption proceeding in nature as well as in civilization. The accumulation of heat capacitive CO 2 in atmosphere is becoming a serious environmental problem. Solid oxides as minerals in the earth shell had been used mainly for heat resistant structural materials as well as for raw materials of metals, but recent advanced chemistry and physics have been manifesting new electronic and chemical potentials hidden in oxides. Current interest and studies on oxides are directed towards two main areas: (1) prevention of CO 2 increase in atmosphere by its fixation and/or by saving the consumption of fossil fuels and (2) discovery and utilization of superfunctionality in oxides. Triggered by Bednorz and Muller's discovery of high Tc superconductor, the latter topics have been attracting rapidly growing interest from viewpoints of both fundamental research and practical application. In commemoration of WOE homecoming to the place of inauguration, a founder of WOE appreciates much to the program committee for providing him with this opportunity of briefing the workshop motivation and of reviewing his research career on oxide materials

Electronic structures near surfaces of perovskite type oxides

International Nuclear Information System (INIS)

Hara, Toru

2005-01-01

This work is intended to draw attention to the origin of the electronic structures near surfaces of perovskite type oxides. Deep states were observed by ultraviolet photoelectron spectroscopic measurements. The film thickness dependent electronic structures near surfaces of (Ba 0.5 Sr 0.5 )TiO 3 thin films were observed. As for the 117-308 nm thick (Ba 0.5 Sr 0.5 )TiO 3 films, deep states were lying at 0.20, 0.55, and 0.85 eV below the quasi-fermi level, respectively. However, as for the 40 nm thick (Ba 0.5 Sr 0.5 )TiO 3 film, the states were overlapped. The A-site doping affected electronic structures near surfaces of SrTiO 3 single crystals. No evolution of deep states in non-doped SrTiO 3 single crystal was observed. However, the evolution of deep states in La-doped SrTiO 3 single crystal was observed

Unconventional aspects of electronic transport in delafossite oxides

Science.gov (United States)

Daou, Ramzy; Frésard, Raymond; Eyert, Volker; Hébert, Sylvie; Maignan, Antoine

2017-12-01

The electronic transport properties of the delafossite oxides ? are usually understood in terms of two well-separated entities, namely the triangular ? and (? layers. Here, we review several cases among this extensive family of materials where the transport depends on the interlayer coupling and displays unconventional properties. We review the doped thermoelectrics based on ? and ?, which show a high-temperature recovery of Fermi-liquid transport exponents, as well as the highly anisotropic metals ?, ?, and ?, where the sheer simplicity of the Fermi surface leads to unconventional transport. We present some of the theoretical tools that have been used to investigate these transport properties and review what can and cannot be learned from the extensive set of electronic structure calculations that have been performed.

Electronic interactions decreasing the activation barrier for the hydrogen electro-oxidation reaction

International Nuclear Information System (INIS)

Santos, Elizabeth; Schmickler, Wolfgang

2008-01-01

A unified model for electrochemical electron transfer reactions which explicitly accounts for the electronic structure of the electrode recently proposed by us is applied to the hydrogen oxidation reaction at different metal electrocatalysts. We focus on the changes produced in the transition state (saddle point) as a consequence of the interactions with d-bands. We discuss different empirical correlations between properties of the metal and catalytic activity proposed in the past. We show which role is played by the band structure of the different metals and its interaction with the molecule for decreasing the activation barrier. Finally, we demonstrate why some metals are better electrocatalysts for the hydrogen electro-oxidation reaction than others

Wide and ultra-wide bandgap oxides: where paradigm-shift photovoltaics meets transparent power electronics

Science.gov (United States)

Pérez-Tomás, Amador; Chikoidze, Ekaterine; Jennings, Michael R.; Russell, Stephen A. O.; Teherani, Ferechteh H.; Bove, Philippe; Sandana, Eric V.; Rogers, David J.

2018-03-01

Oxides represent the largest family of wide bandgap (WBG) semiconductors and also offer a huge potential range of complementary magnetic and electronic properties, such as ferromagnetism, ferroelectricity, antiferroelectricity and high-temperature superconductivity. Here, we review our integration of WBG and ultra WBG semiconductor oxides into different solar cells architectures where they have the role of transparent conductive electrodes and/or barriers bringing unique functionalities into the structure such above bandgap voltages or switchable interfaces. We also give an overview of the state-of-the-art and perspectives for the emerging semiconductor β- Ga2O3, which is widely forecast to herald the next generation of power electronic converters because of the combination of an UWBG with the capacity to conduct electricity. This opens unprecedented possibilities for the monolithic integration in solar cells of both self-powered logic and power electronics functionalities. Therefore, WBG and UWBG oxides have enormous promise to become key enabling technologies for the zero emissions smart integration of the internet of things.

Electronic structure of nanoparticles of substoichometric hexagonal tungsten oxides

International Nuclear Information System (INIS)

Khyzhun, O Y; Solonin, Y M

2007-01-01

X-ray photoelectron spectroscopy (XPS), X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) methods were used to study the electronic structure of hexagonal h-WO 3 and h-WO 2.8 nanoparticles. For comparison, nanopowder substoichiometric monoclinic tungsten oxides with close content of oxygen atoms, namely m-WO 3 and m-WO 2.77 compounds, were also investigated. For the mentioned oxides, XPS valence-band and corelevel spectra, XES O Kα bands and XAS W L III and O 1s edges were derived. The XPS valence-band spectra and O Kα emission bands in the mentioned hexagonal and monoclinic tungsten oxides were compared on a common energy scale. Both the O Kα bands and XPS valence-band spectra broaden somewhat in the sequences h-WO 3 → h-WO 2.8 and m-WO 3 → m-WO 2.77 , with the half-widths of the spectra being somewhat higher for the hexagonal oxides as compared with those for the monoclinic compounds. The effective positive charge state of tungsten atoms in h-WO 2.8 is very close to that in m-WO 2.77 , but the negative charge states of oxygen atoms are close to each other for all the tungsten oxides under consideration

Evaluation of Fenton's Reagent and Activated Persulfate for Treatment of a Pharmaceutical Waste Mixture in Groundwater

DEFF Research Database (Denmark)

Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Kakarla, Prasad

2010-01-01

Soil and groundwater beneath the Kærgård Plantage megasite in Denmark are contaminated with a complex mixture of pharmaceutical wastes, including sulfonamides, barbiturates, aniline, pyridine chlorinated solvents (DNAPL), benzene, toluene, mercury, and cyanide. Regulatory agencies in Denmark...... capacity of the aquifer sediments, pH dropped to within the range of 1 to 3 for all tests. Due to the presence of significant quantities of mercury and cyanide in the target treatment zone and the lowering of pH, batch and continuous-flow column reactors were used to measure mobilization of the mercury......, cyanide, chromium and other metals both within the aqueous and vapour phases. Except the alkaline activation, all the investigated techniques for activating persulfate were able to remove more than 80% of the primary contaminants. Optimization and more dosages led to 98-99% destruction of primary...

Application of Degenerately Doped Metal Oxides in the Study of Photoinduced Interfacial Electron Transfer.

Science.gov (United States)

Farnum, Byron H; Morseth, Zachary A; Brennaman, M Kyle; Papanikolas, John M; Meyer, Thomas J

2015-06-18

Degenerately doped In2O3:Sn semiconductor nanoparticles (nanoITO) have been used to study the photoinduced interfacial electron-transfer reactivity of surface-bound [Ru(II)(bpy)2(4,4'-(PO3H2)2-bpy)](2+) (RuP(2+)) molecules as a function of driving force over a range of 1.8 eV. The metallic properties of the ITO nanoparticles, present within an interconnected mesoporous film, allowed for the driving force to be tuned by controlling their Fermi level with an external bias while their optical transparency allowed for transient absorption spectroscopy to be used to monitor electron-transfer kinetics. Photoinduced electron transfer from excited-state -RuP(2+*) molecules to nanoITO was found to be dependent on applied bias and competitive with nonradiative energy transfer to nanoITO. Back electron transfer from nanoITO to oxidized -RuP(3+) was also dependent on the applied bias but without complication from inter- or intraparticle electron diffusion in the oxide nanoparticles. Analysis of the electron injection kinetics as a function of driving force using Marcus-Gerischer theory resulted in an experimental estimate of the reorganization energy for the excited-state -RuP(3+/2+*) redox couple of λ* = 0.83 eV and an electronic coupling matrix element, arising from electronic wave function overlap between the donor orbital in the molecule and the acceptor orbital(s) in the nanoITO electrode, of Hab = 20-45 cm(-1). Similar analysis of the back electron-transfer kinetics yielded λ = 0.56 eV for the ground-state -RuP(3+/2+) redox couple and Hab = 2-4 cm(-1). The use of these wide band gap, degenerately doped materials provides a unique experimental approach for investigating single-site electron transfer at the surface of oxide nanoparticles.

The effect of electron beam irradiation on lipid oxidation in sausages

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atefeh yousefi

2017-09-01

Full Text Available Introduction: Irradiation treatment is one of the best techniques to extend the shelf-life of meat, without emerging the nutritional properties and sensory quality of irradiated meat products.  However electron -beam  may cause transformations in foods but has been known as to the most easily-applied irradiation technique in food industries. Electron-beam irradiation is an environment friendly, low cost and time effective alternative to other decontamination technologies. Lipid oxidation could produce of irradiated meat. This study aimed at evaluating the state of lipid oxidation of irradiated sausages. Its findings could help the control, improve food safety and quality properties to food industries. Methods: Sausages were purchased in a local supermarket, minced sausages blended for thiobarbituric acid reactive substances (TBARS analysis and divided into 25 g pieces. The samples including one control group and four case groups. Packaged sausage were exposed at doses of 0 (control, 1, 2, 3 and 5 kGy and analyzed on various days 0, 5, 10 and 30. Results: Thiobarbituric acid reactive substances (TBARS has increased as time goes on (P<0.05. A significant relationship was observed on different Doses. But, the maximum of TBARS was observed in 3 kGy. Conclusion: Utilizing of Electron-beam irradiation in low doses does not have significant difference on lipid oxidation. Irradiating of meat products by addition of antioxidants can minimize or avoid the development of rancidity.

Transmission electron microscopy and Raman characterization of copper (I) oxide microspheres composed of nanoparticles

International Nuclear Information System (INIS)

Wang Wenzhong; Tu Ya; Wang Lijuan; Liang Yujie; Shi Honglong

2013-01-01

Highlights: ► Raman spectroscopy of copper (I) oxide microspheres were investigated. ► Infrared active mode is greatly activated in Raman scattering spectrum. ► Infrared active mode shows up in Raman spectrum of copper (I) oxide microspheres. ► The defects existed in spheres could be responsible for the observed Raman property. - Abstract: The high-resolution transmission electron microscope and Raman spectroscopy were used to investigate the microstructures and Raman scattering property of copper (I) oxide microspheres composed of nanoparticles. High-resolution transmission electron microscope images indicate that the copper (I) oxide microspheres are composed of nanoparticles with random growth direction, indicating that there are many defects in microspheres. The Raman spectrum shows that infrared active mode, which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is activated and shows up in Raman scattering spectrum. On the basis of investigations of the microstructure features of copper (I) oxide microspheres, we attribute the appearance of IR active mode in Raman scattering spectrum to the breakdown of the symmetry of the lattice due to the presence of defects in the prepared copper (I) oxide microspheres as observed in HRTEM images.

Silica-Supported Co3O4 Nanoparticles as a Recyclable Catalyst for Rapid Degradation of Azodye

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Ali Baghban

2016-10-01

Full Text Available In this paper, silica nanoparticles with particle size of ~ 10-20 nm were selected as a support for the synthesis of Co3O4 nanoparticles by impregnation of silica nanoparticles in solution of Co(II in a specific concentrations and then calcination to 800 oC. This nanocomposite was then, used as a catalyst for oxidative degradation of methyl orange (MO with ammonium persulfate in aqueous media. Effect of pH, temperature, contact time, amount of oxidant and catalyst were studied in the presence of manuscript. Scanning electron microscope (SEM, electron dispersive spectroscopy (EDS, FT-IR, and ICP-AES analyses were used for analysis of silica-supported Co3O4 (Co3O4/SiO2. Treating MO with ammonium persulfate in the presence of Co3O4/SiO2 led to complete degradation of MO under the optimized conditions. Also, the catalyst exhibited recyclability at least over 10 consecutive runs. Copyright © 2016 BCREC GROUP. All rights reserved Received: 12nd December 2015; Revised: 27th January 2016; Accepted: 27th January 2016 How to Cite: Baghban, A., Doustkhah, E., Rostamnia, S., Aghbash, K.O. (2016. Silica-Supported Co3O4 Nanoparticles as a Recyclable Catalyst for Rapid Degradation of Azodye. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 284-291 (doi:10.9767/bcrec.11.3.568.284-291 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.568.284-291

Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

Science.gov (United States)

Grove, C. A.; Judd, G.; Ansell, G. S.

1972-01-01

Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

Preparation process and properties of LiCoO2/PANI/dodecylbenzenesulfonate composite electrode materials

International Nuclear Information System (INIS)

Ferchichi, Karima; Hbaieb, Souhaira; Amdouni, Noureddine; Kalfat, Rafik; Chevalier, Yves

2013-01-01

Composite materials that combine the lithium exchanging material LiCoO 2 and the conductive polymer poly(aniline) (PANI) have been investigated regarding their possible application to electrode materials of lithium batteries. Such composite materials have been prepared by means of polymerization of aniline in acidic suspensions of LiCoO 2 particles. PANI was synthesized by oxidative polymerization of aniline by ammonium persulfate in the presence of sodium dodecylbenzenesulfonate (SDBS) as a micellar template and dopant. The composite material consisted in LiCoO 2 particles dispersed in a continuous matrix of PANI. The ribbon-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The conductive material had conductivity close to that of PANI because the LiCoO 2 content of the composite material was low. The presence of the poorly conductive inorganic phase caused a significant loss of conductivity, showing that LiCoO 2 blocked electronic transfers between PANI crystallites. Ammonium persulfate caused the loss of lithium from LiCoO 2 when it was used at high concentration in the polymerization recipe. In this case a new phase made of Co 3 O 4 formed by chemical decomposition of Li x CoO 2 . Thin films prepared from stable suspensions of composite materials in water show comparable electrical performance to that measured for bulk materials. - Highlights: • LiCoO 2 was incorporated in a conductive polymer matrix made of PANI. • The hybrid material retained the high conductive properties of PANI. • Loss of lithium by persulfate oxidation caused conversion of LiCoO 2 into Co 3 O 4

Facile synthesis of highly reactive and stable Fe-doped g-C3N4 composites for peroxymonosulfate activation: A novel nonradical oxidation process.

Science.gov (United States)

Feng, Yong; Liao, Changzhong; Kong, Lingjun; Wu, Deli; Liu, Yiming; Lee, Po-Heng; Shih, Kaimin

2018-07-15

Ferrous ions (Fe 2+ ) are environmentally friendly materials but show extremely inefficient persulfate activation. Polymeric graphitic carbon nitride (g-C 3 N 4 ) has recently shown potential to activate persulfates, but the process requires intense light irradiation. To overcome these drawbacks, we designed an innovative heterogeneous iron catalyst by doping Fe into g-C 3 N 4 (Fe-g-C 3 N 4 ) and used it to activate peroxymonosulfate (PMS) for degradation of pollutant phenol. The catalysts synthesized were fully characterized with various techniques, such as X-ray diffraction, Mössbauer spectroscopy, and X-ray photoelectron spectroscopy. Fe was found to be coordinated with the framework of g-C 3 N 4 . Approximately 100% degradation of phenol was achieved with Fe-g-C 3 N 4 after 20 min of reaction, whereas less than 5% degradation of phenol was achieved with Fe 2+ . Fe-g-C 3 N 4 -PMS had a wide effective pH range, and its reactivity was nearly independent of natural illumination. In contrast to the previously proposed radical mechanisms, quenching experiments revealed that nonradical oxidation contributed to the observed degradation. The OO bond in the activated PMS likely underwent heterolysis, producing high-valence iron species (Fe IV O) as the primary active species. These findings have important implications for the development of a selective heterogeneous nonradical-oxidation process. Copyright © 2018 Elsevier B.V. All rights reserved.

Surface and Core Electronic Structure of Oxidized Silicon Nanocrystals

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Noor A. Nama

2010-01-01

Full Text Available Ab initio restricted Hartree-Fock method within the framework of large unit cell formalism is used to simulate silicon nanocrystals between 216 and 1000 atoms (1.6–2.65 nm in diameter that include Bravais and primitive cell multiples. The investigated properties include core and oxidized surface properties. Results revealed that electronic properties converge to some limit as the size of the nanocrystal increases. Increasing the size of the core of a nanocrystal resulted in an increase of the energy gap, valence band width, and cohesive energy. The lattice constant of the core and oxidized surface parts shows a decreasing trend as the nanocrystal increases in a size that converges to 5.28 Ǻ in a good agreement with the experiment. Surface and core convergence to the same lattice constant reflects good adherence of oxide layer at the surface. The core density of states shows highly degenerate states that split at the oxygenated (001-(1×1 surface due to symmetry breaking. The nanocrystal surface shows smaller gap and higher valence and conduction bands when compared to the core part, due to oxygen surface atoms and reduced structural symmetry. The smaller surface energy gap shows that energy gap of the nanocrystal is controlled by the surface part. Unlike the core part, the surface part shows a descending energy gap that proves its obedience to quantum confinement effects. Nanocrystal geometry proved to have some influence on all electronic properties including the energy gap.

Phosphorene oxide: stability and electronic properties of a novel two-dimensional material.

Science.gov (United States)

Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P

2015-01-14

Phosphorene, the monolayer form of (black) phosphorus, was recently exfoliated from its bulk counterpart. Phosphorene oxide, by analogy to graphene oxide, is expected to have novel chemical and electronic properties, and may provide an alternative route to the synthesis of phosphorene. In this research, the physical and chemical properties of phosphorene oxide including its formation by oxygen adsorption on the bare phosphorene was investigated. Analysis of the phonon dispersion curves finds stoichiometric and non-stoichiometric oxide configurations to be stable at ambient conditions, thus suggesting that the oxygen adsorption may not degrade the phosphorene. The nature of the band gap of the oxides depends on the degree of functionalization of phosphorene; an indirect gap is predicted for the non-stoichiometric configurations, whereas a direct gap is predicted for the stoichiometric oxide. Application of mechanical strain or an external electric field leads to tunability of the band gap of the phosphorene oxide. In contrast to the case of the bare phosphorene, dependence of the diode-like asymmetric current-voltage response on the degree of stoichiometry is predicted for the phosphorene oxide.

Study of the electronic structure of pure aluminium, aluminium oxide and nitride by spectroscopy of electrons excited under electronic and photonic bombardment (X and UV)

International Nuclear Information System (INIS)

Gautier-Soyer, Martine

1985-01-01

This research thesis reports the use of electron spectroscopy with electrons excited under electronic or photonic (X or UV) bombardment for the study of electronic state density of aluminium, aluminium oxide (Al 2 O 3 ) and aluminium nitride (AlN). The objective is to get an insight into phenomena related to technological problems of adherence, wear, lubrication, corrosion or breakdown met in metals, insulators and semiconductors. The author highlighted the presence of occupied surface states on Al(111) and Al(100), and electronic levels localised in the forbidden band of Al 2 O 3 and AlN, induced by structural defects which promote surface reactivity [fr

First-principles analysis of structural and opto-electronic properties of indium tin oxide

Science.gov (United States)

Tripathi, Madhvendra Nath; Shida, Kazuhito; Sahara, Ryoji; Mizuseki, Hiroshi; Kawazoe, Yoshiyuki

2012-05-01

Density functional theory (DFT) and DFT + U (DFT with on-site Coulomb repulsion corrections) calculations have been carried out to study the structural and opto-electronic properties of indium tin oxide (ITO) for both the oxidized and reduced environment conditions. Some of the results obtained by DFT calculations differ from the experimental observations, such as uncertain indication for the site preference of tin atom to replace indium atom at b-site or d-site, underestimation of local inward relaxation in the first oxygen polyhedra around tin atom, and also the improper estimation of electronic density of states and hence resulting in an inappropriate optical spectra of ITO. These discrepancies of theoretical outcomes with experimental observations in ITO arise mainly due to the underestimation of the cationic 4d levels within standard DFT calculations. Henceforth, the inclusion of on-site corrections within DFT + U framework significantly modifies the theoretical results in better agreement to the experimental observations. Within this framework, our calculations show that the indium b-site is preferential site over d-site for tin atom substitution in indium oxide under both the oxidized and reduced conditions. Moreover, the calculated average inward relaxation value of 0.16 Å around tin atom is in good agreement with the experimental value of 0.18 Å. Furthermore, DFT + U significantly modify the electronic structure and consequently induce modifications in the calculated optical spectra of ITO.

Electrochemical One-Electron Oxidation of Low-Generation Polyamidoamine-Type Dendrimers with a 1,4-Phenylenediamine Core

DEFF Research Database (Denmark)

Hammerich, Ole; Hansen, Thomas; Thorvildsen, Asbjørn

2009-01-01

voltammetry (DPV) in methanol, acetonitrile, dichloromethane, and dimethyl sulfoxide. The dendrimers are more difficult to oxidize than N,N,N',N'-tetramethyl-p-phenylenediamine (TMePD). The oxidation potentials decrease with increasing dendrimer generation up to G0.5, after which the potential is essentially......A series of polyamidoamine (PAMAM)-type dendrimers with a 1,4-phenylenediamine (PD) core is prepared from PD by procedures including Michael addition of methyl acrylate followed by aminolysis with 1,2-ethanediamine. Their one-electron oxidation potentials are determined by differential pulse......,N,N',N'-tetra-n-alkyl-p-phenylenediamines, including a planar arrangement of the atoms linked to the two PD nitrogen atoms. Thus, the effect of chain size on the oxidation potential appears to be caused primarily by a simple electronic effect. The calculations indicate considerable reorientation of the dendrimer side chains on oxidation, presumably...

One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

Science.gov (United States)

Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

2014-06-01

The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

Electron Band Alignment at Interfaces of Semiconductors with Insulating Oxides: An Internal Photoemission Study

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Valeri V. Afanas'ev

2014-01-01

Full Text Available Evolution of the electron energy band alignment at interfaces between different semiconductors and wide-gap oxide insulators is examined using the internal photoemission spectroscopy, which is based on observations of optically-induced electron (or hole transitions across the semiconductor/insulator barrier. Interfaces of various semiconductors ranging from the conventional silicon to the high-mobility Ge-based (Ge, Si1-xGex, Ge1-xSnx and AIIIBV group (GaAs, InxGa1-xAs, InAs, GaP, InP, GaSb, InSb materials were studied revealing several general trends in the evolution of band offsets. It is found that in the oxides of metals with cation radii larger than ≈0.7 Å, the oxide valence band top remains nearly at the same energy (±0.2 eV irrespective of the cation sort. Using this result, it becomes possible to predict the interface band alignment between oxides and semiconductors as well as between dissimilar insulating oxides on the basis of the oxide bandgap width which are also affected by crystallization. By contrast, oxides of light elements, for example, Be, Mg, Al, Si, and Sc exhibit significant shifts of the valence band top. General trends in band lineup variations caused by a change in the composition of semiconductor photoemission material are also revealed.

In situ studies of oxide nucleation, growth, and transformation using slow electrons

Science.gov (United States)

Flege, Jan Ingo; Grinter, David C.

2018-05-01

Surface processes such as metal oxidation and metal oxide growth invariably influence the physical and chemical properties of materials and determine their interaction with their surroundings and hence their functionality in many technical applications. On a fundamental level, these processes are found to be governed by a complex interplay of thermodynamic variables and kinetic constraints, resulting in a rich variety of material-specific phenomena. In this review article, we discuss recent results and insights on transition metal oxidation and rare-earth oxide growth acquired by low-energy electron microscopy and related techniques. We demonstrate that the use of in situ surface sensitive methods is a prerequisite to gaining a deeper understanding of the underlying concepts and the mechanisms responsible for the emerging oxide structure and morphology. Furthermore, examples will be provided on how structural and chemical modifications of the oxide films and nanostructures can be followed in real-time and analyzed in terms of local reactivity and cooperative effects relevant for heterogeneous model catalysis.

Remediation of TCE-contaminated groundwater using acid/BOF slag enhanced chemical oxidation.

Science.gov (United States)

Tsai, T T; Kao, C M; Wang, J Y

2011-04-01

The objective of this study was to evaluate the potential of applying acid/H(2)O(2)/basic oxygen furnace slag (BOF slag) and acid/S(2)O(8)(2-)/BOF slag systems to enhance the chemical oxidation of trichloroethylene (TCE)-contaminated groundwater. Results from the bench-scale study indicate that TCE oxidation via the Fenton-like oxidation process can be enhanced with the addition of BOF slag at low pH (pH=2-5.2) and neutral (pH=7.1) conditions. Because the BOF slag has iron abundant properties (14% of FeO and 6% of Fe(2)O(3)), it can be sustainably reused for the supplement of iron minerals during the Fenton-like or persulfate oxidation processes. Results indicate that higher TCE removal efficiency (84%) was obtained with the addition of inorganic acid for the activation of Fenton-like reaction compared with the experiments with organic acids addition (with efficiency of 10-15% lower) (BOF slag=10gL(-1); initial pH=5.2). This could be due to the fact that organic acids would compete with TCE for available oxidants. Results also indicate that the pH value had a linear correlation with the observed first-order decay constant of TCE, and thus, lower pH caused a higher TCE oxidation rate. Copyright © 2011 Elsevier Ltd. All rights reserved.

A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

CERN Document Server

An, X; Rainforth, W M; Chen, L

2003-01-01

The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 mu m). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 mu m), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). G...

Conversion of sulfur and nitrogen oxides in air under exposure to microsecond electron beams

International Nuclear Information System (INIS)

Denisov, G.V.; Kuznetsov, D.L.; Novoselov, Yu.N.; Tkachenko, R.M.

2002-01-01

Flue gases of power plants realizing sulfur and nitrogen oxides into the atmosphere represent one of the environmental pollution sources. Paper presents the results of experimental investigations of conversion of sulfur and nitrogen oxides in the ionized gas mixture simulating composition of off-gases of thermal power stations. Pulse beam of microsecond duration electrons was used as a source of ionization. Mutual influence of both types of oxides on process of their conversion is shown. One studied possible kinetic mechanisms to remove sulfur and nitrogen oxides from gaseous mixture [ru

Electronic, vibrational and related properties of group IV metal oxides by ab initio calculations

International Nuclear Information System (INIS)

Leite Alves, H.W.; Silva, C.C.; Lino, A.T.; Borges, P.D.; Scolfaro, L.M.R.; Silva, E.F. da

2008-01-01

We present our theoretical results for the structural, electronic, vibrational and optical properties of MO 2 (M = Sn, Zr, Hf and Ti) obtained by first-principles calculations. Relativistic effects are demonstrated to be important for a realistic description of the detailed structure of the electronic frequency-dependent dielectric function, as well as of the carrier effective masses. Based on our results, we found that the main contribution of the high values calculated for the oxides dielectric constants arises from the vibrational properties of these oxides, and the vibrational static dielectric constant values diminish with increasing pressure

Radioprotective efficacy of bisarylidene cyclopentanone on electron beam radiation induced oxidative stress in Drosophila melanogaster

International Nuclear Information System (INIS)

Darshan Raj, C.G.; Sarojini, B.K.; Musthafa Khaleel, V.; Ramesh, S.R.; Ramakrishna, M.K.; Narayana, B.; Sanjeev, Ganesh

2010-01-01

Present study was carried out for evaluating the radioprotective effect of bischalcone (2E, 5E) - 2,5-bis (3-methoxy-4-hydroxy-benzylidene) cyclopentanone (curcumin analog (CA)), on electron beam radiation induced oxidative stress in Drosophila melanogaster adults. The oxidative stress markers and antioxidants included superoxide dismutase (SOD) and catalase (CAT). The oxidative stress was induced at 1.5 Gy. (author)

Potential for chlorate interference in ion chromatographic determination of total nitrogen in natural waters following alkaline persulfate digestion.

Science.gov (United States)

Halstead, J A; Edwards, J; Soracco, R J; Armstrong, R W

1999-10-01

Determination of total nitrogen in aqueous samples after thermal potassium peroxydisulfate (persulfate) digestion is a commonly used alternative to the tedious Kjeldahl procedure. When ion chromatography is used to quantify the nitrate formed during digestion, there is a potential for interference from a chlorate peak if the digested sample initially contained chloride in concentrations close to or greater than the concentration of nitrogen. It was determined that this interference can be avoided either by using chromatographic conditions which cleanly resolve the nitrate and chlorate peaks (e.g., the Dionex AG9-HG column) or by using digestion reagent concentrations chosen to maintain a high pH throughout the digestion. The second alternative is not a viable option for investigators using a single digestion for both total nitrogen (TN) and total phosphorus (TP) analysis.

The effect of energetic electron precipitation on the nitric oxide density in the lower thermosphere

International Nuclear Information System (INIS)

Saetre, Camilla

2006-12-01

The objective of this thesis has been the study of the chemical effects of the electron precipitation in the upper atmosphere, and mainly the increase of thermospheric nitric oxide (NO). NO plays an important role in the temperature balance for the mesosphere and thermosphere.In this project auroral electron precipitation data, derived from the Polar Ionospheric X-ray Imaging Experiment (PIXIE) and the Ultraviolet Imager (UVI) on board the Polar satellite, have been used together with NO density measurements from the Student Nitric Oxide Explorer (SNOE)

The one-electron oxidation of a dithiolate molecule: the importance of chemical intuition.

Science.gov (United States)

Bushnell, Eric A C; Burns, Thomas D; Boyd, Russell J

2014-05-14

A series of nine commonly used density functional methods were assessed to accurately predict the oxidation potential of the (C2H2S2(-2)/C2H2S2(•-)) redox couple. It was found that due to their greater tendency for charge delocalization the GGA functionals predict a structure where the radical electron is delocalized within the alkene backbone of C2H2S2(•-), whereas the hybrid functionals and the reference QCISD/cc-pVTZ predict that the radical electron remains localized on the sulfurs. However, chemical intuition suggests that the results obtained with the GGA functionals should be correct. Indeed, with the use of the geometries obtained at the HCTH/6-311++G(3df,3pd) level of theory both the QCISD and hybrid DFT methods yield a molecule with a delocalized electron. Notably, this new molecule lies at least 53 kJ mol(-1) lower in energy than the previously optimized one that had a localized radical. Using these new structures the calculated oxidation potential was found to be 2.71-2.97 V for the nine DFT functionals tested. The M06-L functional provided the best agreement with the QCISD/cc-pVTZ reference oxidation potential of 3.28 V.

Atmospheric nitrous oxide produced by solar protons and relativistic electrons

International Nuclear Information System (INIS)

Prasad, S.S.; Zipf, E.C.

1981-01-01

An alternative means of nitric oxide production in the stratosphere to that of direct formation in the upper atmosphere by solar proton (SP) events and by relativistic electron precipitation (REP) events from the Earth's radiation belt, is described. It is suggested that nitrous oxide is produced in the mesosphere and then migrates downward and is converted in the stratosphere to NO by the reaction N 2 O + O( 1 D) → 2 NO. Such a process could amplify the direct NO production by >10%. Mesospheric nitrous oxide mixing ratios increase to values as high as 6 x 10 -7 due to REP- and SP- related production. Lateral transport will reduce these high values but mesospheric mixing ratios of N 2 O in the high latitudes would approach 10 -7 , considerably greater than those expected on the basis of theories which neglect REP- and SP-related production of this species. (U.K.)

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics.

Science.gov (United States)

Park, Minjoon; Do, Kyungsik; Kim, Jaemin; Son, Donghee; Koo, Ja Hoon; Park, Jinkyung; Song, Jun-Kyul; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

2015-05-01

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics are developed. The use of nanomaterials (single wall nanotubes and silver nanoparticles) embedded in the oxide nanomembranes significantly enhances mechanical and thermal sensitivities. These mechanical and thermal sensors are utilized in wheelchair control and hypothermia detection, which are useful for patients with strokes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electronic structure and charge transport in nonstoichiometric tantalum oxide

Science.gov (United States)

Perevalov, T. V.; Gritsenko, V. A.; Gismatulin, A. A.; Voronkovskii, V. A.; Gerasimova, A. K.; Aliev, V. Sh; Prosvirin, I. A.

2018-06-01

The atomic and electronic structure of nonstoichiometric oxygen-deficient tantalum oxide TaO x<2.5 grown by ion beam sputtering deposition was studied. The TaO x film content was analyzed by x-ray photoelectron spectroscopy and by quantum-chemistry simulation. TaO x is composed of Ta2O5, metallic tantalum clusters and tantalum suboxides. A method for evaluating the stoichiometry parameter of TaO x from the comparison of experimental and theoretical photoelectron valence band spectra is proposed. The charge transport properties of TaO x were experimentally studied and the transport mechanism was quantitatively analyzed with four theoretical dielectric conductivity models. It was found that the charge transport in almost stoichiometric and nonstoichiometric tantalum oxide can be consistently described by the phonon-assisted tunneling between traps.

The electronic structure and metal-insulator transitions in vanadium oxides

International Nuclear Information System (INIS)

Mossanek, Rodrigo Jose Ochekoski

2010-01-01

The electronic structure and metal-insulator transitions in vanadium oxides (SrVO_3, CaVO_3, LaVO_3 and YVO_3) are studied here. The purpose is to show a new interpretation to the spectra which is coherent with the changes across the metal-insulator transition. The main experimental techniques are the X-ray photoemission (PES) and X-ray absorption (XAS) spectroscopies. The spectra are interpreted with cluster model, band structure and atomic multiplet calculations. The presence of charge-transfer satellites in the core-level PES spectra showed that these vanadium oxides cannot be classified in the Mott-Hubbard regime. Further, the valence band and core-level spectra presented a similar behavior across the metal insulator transition. In fact, the structures in the spectra and their changes are determined by the different screening channels present in the metallic or insulating phases. The calculated spectral weight showed that the coherent fluctuations dominate the spectra at the Fermi level and give the metallic character to the SrVO_3 and CaVO_3 compounds. The vanishing of this charge fluctuation and the replacement by the Mott-Hubbard screening in the LaVO_3 and YVO_3 systems is ultimately responsible for the opening of a band gap and the insulating character. Further, the correlation effects are, indeed, important to the occupied electronic structure (coherent and incoherent peaks). On the other hand, the unoccupied electronic structure is dominated by exchange and crystal field effects (t2g and eg sub-bands of majority and minority spins). The optical conductivity spectrum was obtained by convoluting the removal and addition states. It showed that the oxygen states, as well as the crystal field and exchange effects are necessary to correctly compare and interpret the experimental results. Further, a correlation at the charge-transfer region of the core-level and valence band optical spectra was observed, which could be extended to other transition metal oxides

Spectroscopy study of electron spin resonance of coal oxidation of different rank

International Nuclear Information System (INIS)

Enciso Prieto, Hector Manuel

1992-01-01

The present work constitutes an initial step for the knowledge of the coal oxidation, with the purpose of preventing the adverse influences caused by this phenomenon in the physical-chemical characteristics and in the tendency to the spontaneous combustion. Since the knowledge the influence of the free radicals in this process, their relative concentration was measured by means of the use of the technique of resonance spin electron. This technique measures the absorption of electromagnetic radiation, generally in the microwaves region, for the materials that not have electrons matched up in a strong magnetic field. In the essays of oxidation three coal of different range and different characteristics of mass were used and it was studied the influence of the temperature, particle size and the range. The results showed that the coal of Guacheta (bituminous low in volatile) it presents bigger concentration of free radicals, after the reaction with the atmospheric oxygen, with regard to the coal of the Cerrejon (bituminous high in volatile B) and Amaga (bituminous high in volatile C). Although this doesn't indicate that the coal of Guacheta is that more easily is oxidized, but rather it possibly presents stabilization of radicals for resonance. It concluded that there are differences in the oxidation mechanism between coal of different rank and different agglomeration properties

Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

KAUST Repository

Li, Jingrui

2015-07-29

The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

Electronic Structure of the Perylene / Zinc Oxide Interface: A Computational Study of Photoinduced Electron Transfer and Impact of Surface Defects

KAUST Repository

Li, Jingrui; Li, Hong; Winget, Paul; Bredas, Jean-Luc

2015-01-01

The electronic properties of dye-sensitized semiconductor surfaces consisting of pery- lene chromophores chemisorbed on zinc oxide via different spacer-anchor groups, have been studied at the density-functional-theory level. The energy distributions of the donor states and the rates of photoinduced electron transfer from dye to surface are predicted. We evaluate in particular the impact of saturated versus unsaturated aliphatic spacer groups inserted between the perylene chromophore and the semiconductor as well as the influence of surface defects on the electron-injection rates.

Epitaxial Lift-Off of Centimeter-Scaled Spinel Ferrite Oxide Thin Films for Flexible Electronics.

Science.gov (United States)

Shen, Lvkang; Wu, Liang; Sheng, Quan; Ma, Chunrui; Zhang, Yong; Lu, Lu; Ma, Ji; Ma, Jing; Bian, Jihong; Yang, Yaodong; Chen, Aiping; Lu, Xiaoli; Liu, Ming; Wang, Hong; Jia, Chun-Lin

2017-09-01

Mechanical flexibility of electronic devices has attracted much attention from research due to the great demand in practical applications and rich commercial value. Integration of functional oxide materials in flexible polymer materials has proven an effective way to achieve flexibility of functional electronic devices. However, the chemical and mechanical incompatibilities at the interfaces of dissimilar materials make it still a big challenge to synthesize high-quality single-crystalline oxide thin film directly on flexible polymer substrates. This study reports an improved method that is employed to successfully transfer a centimeter-scaled single-crystalline LiFe 5 O 8 thin film on polyimide substrate. Structural characterizations show that the transferred films have essentially no difference in comparison with the as-grown films with respect to the microstructure. In particular, the transferred LiFe 5 O 8 films exhibit excellent magnetic properties under various mechanical bending statuses and show excellent fatigue properties during the bending cycle tests. These results demonstrate that the improved transfer method provides an effective way to compose single-crystalline functional oxide thin films onto flexible substrates for applications in flexible and wearable electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Topotactic reduction yielding black titanium oxide nanostructures as metallic electronic conductors.

Science.gov (United States)

Tominaka, Satoshi

2012-10-01

Detailed analyses of reduced, single crystal, rutile-type TiO(2) via high-resolution transmission electron microscopy (TEM) are reported which reveal that the reduction proceeds topotactically via interstitial diffusion of Ti ions at low temperature, around 350 °C. This important finding encouraged the production of various nanostructured reduced titanium oxides from TiO(2) precursors with morphology retention, and in the process, the synthesis of black titanium oxide nanorods using TiO(2) nanorods was demonstrated. Interestingly, as opposed to the semiconductive behavior of Ti(2)O(3) synthesized at high temperature, topotactically synthesized Ti(2)O(3) exhibits metallic electrical resistance, and the value at room temperature is quite low (topotactically synthesized Ti(2)O(3). This work shows that topotactically reduced titanium oxides can have fascinating properties as well as nanostructures.

Transmission electron microscopy characterization of Zircaloy-4 and ZIRLO™ oxide layers

International Nuclear Information System (INIS)

Gabory, Benoit de; Motta, Arthur T.; Wang, Ke

2015-01-01

Waterside corrosion of zirconium alloy nuclear fuel cladding varies markedly from one alloy to another. In addition, for a given alloy, the corrosion rate evolves during the corrosion process, most notably when the oxide loses its stability at the oxide transition. In an effort to understand the mechanism resulting in the variations of corrosion rate observed at the oxide transition, oxide layers formed on Zircaloy-4 and ZIRLO™ in high temperature water autoclave environments, and archived before and after the transition, are characterized using transmission electron microscopy. The study characterizes and compares the oxide morphology in both alloys at different times during the corrosion process, in an effort to understand the oxide growth mechanism for these alloys. Results show that the oxide is mainly composed of monoclinic ZrO 2 , with a preponderance of columnar oxide grains which extend to the oxide/metal interface. The oxide formed right after the transition has occurred, exhibits a 150 nm-wide layer of small equiaxed grains with high tetragonal oxide fraction. This layer has a similar morphology and structure as the first oxide layer formed (observed near the oxide/water interface). A study of the oxygen-rich region near the oxide/metal interface reveals a complex structure of different phases at different stages of corrosion. The interface exhibits an intermediate layer, identified as ZrO, a discontinuous layer of “blocky” Zr 3 O grains embedded in the ZrO layer, and a suboxide layer corresponding to an oxygen saturated solid solution in the metal matrix side. The thickness of this interfacial layer decreased markedly at the transition. Hydrides are also observed in that region, with a definite orientation relationship with the matrix. The observations of the oxide/metal interface are qualitatively similar for the two alloys but quantitatively different. The incorporation of intermetallic precipitates into the oxide layer is also studied, and

Effect of oxygen deficiency on electronic properties and local structure of amorphous tantalum oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Denny, Yus Rama [Department of Physics Education, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Firmansyah, Teguh [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Oh, Suhk Kun [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Yang, Dong-Seok [Department of Physics Education, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Heo, Sung; Chung, JaeGwan; Lee, Jae Cheol [Analytical Engineering Center, Samsung Advanced Institute of Technology, Suwon 16678 (Korea, Republic of)

2016-10-15

Highlights: • The effect of oxygen flow rate on electronic properties and local structure of tantalum oxide thin films was studied. • The oxygen deficiency induced the nonstoichiometric state a-TaOx. • A small peak at 1.97 eV above the valence band side appeared on nonstoichiometric Ta{sub 2}O{sub 5} thin films. • The oxygen flow rate can change the local electronic structure of tantalum oxide thin films. - Abstract: The dependence of electronic properties and local structure of tantalum oxide thin film on oxygen deficiency have been investigated by means of X-ray photoelectron spectroscopy (XPS), Reflection Electron Energy Loss Spectroscopy (REELS), and X-ray absorption spectroscopy (XAS). The XPS results showed that the oxygen flow rate change results in the appearance of features in the Ta 4f at the binding energies of 23.2 eV, 24.4 eV, 25.8, and 27.3 eV whose peaks are attributed to Ta{sup 1+}, Ta{sup 2+}, Ta{sup 3+}/Ta{sup 4+}, and Ta{sup 5+}, respectively. The presence of nonstoichiometric state from tantalum oxide (TaOx) thin films could be generated by the oxygen vacancies. In addition, XAS spectra manifested both the increase of coordination number of the first Ta-O shell and a considerable reduction of the Ta-O bond distance with the decrease of oxygen deficiency.

Ratiometric Signaling of Hypochlorite by the Oxidative Cleavage of Sulfonhydrazide-Based Rhodamine-Dansyl Dyad.

Science.gov (United States)

Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

2015-09-08

A reaction-based probe 1 for hypochlorite signaling was designed by the conjugation of two fluorophores, rhodamine and dansyl moieties, by the reaction of rhodamine B base with dansylhydrazine. Probe 1 exhibited pronounced hypochlorite-selective chromogenic and fluorescent signaling behavior over other oxidants used in practical applications, such as hydrogen peroxide, peracetic acid, and ammonium persulfate, as well as commonly encountered metal ions and anions. Signaling was attributed to the hypochlorite-induced oxidative cleavage of the sulfonhydrazide linkage of the probe. In particular, favorable ratiometric fluorescence signaling was possible by utilizing the emissions of the two fluorophores. A detection limit of 1.13 × 10(-6) M (0.058 ppm) was estimated for the determination of hypochlorite. A paper-based test strip was prepared and was used as a semiquantitative indicator for the presence of hypochlorite in aqueous solutions. The probe was also successfully applied for the determination of hypochlorite in practical tap water samples.

A study of internal oxidation in carburized steels by glow discharge optical emission spectroscopy and scanning electron microscopy

International Nuclear Information System (INIS)

An, X; Cawley, J.; Rainforth, W.M.; Chen, L.

2003-01-01

The internal oxidation of Cr-Mn carburizing steel was studied. Internal oxidation was induced using a commercial carburizing process. Sputter erosion coupled with glow discharge optical emission spectroscopy (GDOES) was used to determine the depth profile elemental distribution within the internal oxidation layer (<10 μm). In addition, scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) studies were carried out on selected sputter eroded surfaces. Oxide type was identified primarily by transmission electron microscopy (TEM). The carburized surface was found to consist of a continuous oxide layer, followed by a complex internal oxidation layer, where Cr and Mn oxides were found to populate grain boundaries in a globular form in the near surface region. At greater depths (5-10 μm), Si oxides formed as a grain boundary network. The internal oxides (mainly complex oxides) grew quickly during the initial stages of the carburizing process (2 h, 800 deg. C+3 h, 930 deg. C). GDOES proved to be an excellent tool for the quantification of oxidation and element distribution as a function of depth, particularly when combined with SEM and TEM to identify oxide type and morphology

Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

Energy Technology Data Exchange (ETDEWEB)

Leduc, Jennifer; Mathur, Sanjay [Institute of Inorganic Chemistry, University of Cologne (Germany); Pacold, Joseph I.; Shuh, David K. [Chemical Sciences Division, The Glenn T. Seaborg Center, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Dong, Chung-Li [Department of Physics, Tamkang University, Tamsui, Taiwan (China)

2018-01-17

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO{sub 2} nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Uranium oxide nanocrystals by microwave-assisted thermal decomposition. Electronic and structural properties

International Nuclear Information System (INIS)

Leduc, Jennifer; Mathur, Sanjay; Pacold, Joseph I.; Shuh, David K.; Dong, Chung-Li

2018-01-01

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase-pure, crystalline UO 2 nanoparticles via microwave-assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Reduced coupling of oxidative phosphorylation in vivo precedes electron transport chain defects due to mild oxidative stress in mice.

Directory of Open Access Journals (Sweden)

Michael P Siegel

Full Text Available Oxidative stress and mitochondrial function are at the core of many degenerative conditions. However, the interaction between oxidative stress and in vivo mitochondrial function is unclear. We used both pharmacological (2 week paraquat (PQ treatment of wild type mice and transgenic (mice lacking Cu, Zn-superoxide dismutase (SOD1(-/- models to test the effect of oxidative stress on in vivo mitochondrial function in skeletal muscle. Magnetic resonance and optical spectroscopy were used to measure mitochondrial ATP and oxygen fluxes and cell energetic state. In both models of oxidative stress, coupling of oxidative phosphorylation was significantly lower (lower P/O at rest in vivo in skeletal muscle and was dose-dependent in the PQ model. Despite this reduction in efficiency, in vivo mitochondrial phosphorylation capacity (ATPmax was maintained in both models, and ex vivo mitochondrial respiration in permeabilized muscle fibers was unchanged following PQ treatment. In association with the reduced P/O, PQ treatment led to a dose-dependent reduction in PCr/ATP ratio and increased phosphorylation of AMPK. These results indicate that oxidative stress uncouples oxidative phosphorylation in vivo and results in energetic stress in the absence of defects in the mitochondrial electron transport chain.

The one-electron oxidation of a dithiolate molecule: The importance of chemical intuition

International Nuclear Information System (INIS)

Bushnell, Eric A. C.; Burns, Thomas D.; Boyd, Russell J.

2014-01-01

A series of nine commonly used density functional methods were assessed to accurately predict the oxidation potential of the (C 2 H 2 S 2 −2 /C 2 H 2 S 2 •− ) redox couple. It was found that due to their greater tendency for charge delocalization the GGA functionals predict a structure where the radical electron is delocalized within the alkene backbone of C 2 H 2 S 2 •− , whereas the hybrid functionals and the reference QCISD/cc-pVTZ predict that the radical electron remains localized on the sulfurs. However, chemical intuition suggests that the results obtained with the GGA functionals should be correct. Indeed, with the use of the geometries obtained at the HCTH/6-311++G(3df,3pd) level of theory both the QCISD and hybrid DFT methods yield a molecule with a delocalized electron. Notably, this new molecule lies at least 53 kJ mol −1 lower in energy than the previously optimized one that had a localized radical. Using these new structures the calculated oxidation potential was found to be 2.71–2.97 V for the nine DFT functionals tested. The M06-L functional provided the best agreement with the QCISD/cc-pVTZ reference oxidation potential of 3.28 V

The one-electron oxidation of a dithiolate molecule: The importance of chemical intuition

Energy Technology Data Exchange (ETDEWEB)

Bushnell, Eric A. C.; Burns, Thomas D.; Boyd, Russell J., E-mail: russell.boyd@dal.ca [Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4R2 (Canada)

2014-05-14

A series of nine commonly used density functional methods were assessed to accurately predict the oxidation potential of the (C{sub 2}H{sub 2}S{sub 2}{sup −2}/C{sub 2}H{sub 2}S{sub 2}{sup •−}) redox couple. It was found that due to their greater tendency for charge delocalization the GGA functionals predict a structure where the radical electron is delocalized within the alkene backbone of C{sub 2}H{sub 2}S{sub 2}{sup •−}, whereas the hybrid functionals and the reference QCISD/cc-pVTZ predict that the radical electron remains localized on the sulfurs. However, chemical intuition suggests that the results obtained with the GGA functionals should be correct. Indeed, with the use of the geometries obtained at the HCTH/6-311++G(3df,3pd) level of theory both the QCISD and hybrid DFT methods yield a molecule with a delocalized electron. Notably, this new molecule lies at least 53 kJ mol{sup −1} lower in energy than the previously optimized one that had a localized radical. Using these new structures the calculated oxidation potential was found to be 2.71–2.97 V for the nine DFT functionals tested. The M06-L functional provided the best agreement with the QCISD/cc-pVTZ reference oxidation potential of 3.28 V.

Recovery of microbial diversity and activity during bioremediation following chemical oxidation of diesel contaminated soils.

Science.gov (United States)

Sutton, Nora B; Langenhoff, Alette A M; Lasso, Daniel Hidalgo; van der Zaan, Bas; van Gaans, Pauline; Maphosa, Farai; Smidt, Hauke; Grotenhuis, Tim; Rijnaarts, Huub H M

2014-03-01

To improve the coupling of in situ chemical oxidation and in situ bioremediation, a systematic analysis was performed of the effect of chemical oxidation with Fenton's reagent, modified Fenton's reagent, permanganate, or persulfate, on microbial diversity and activity during 8 weeks of incubation in two diesel-contaminated soils (peat and fill). Chemical oxidant and soil type affected the microbial community diversity and biodegradation activity; however, this was only observed following treatment with Fenton's reagent and modified Fenton's reagent, and in the biotic control without oxidation. Differences in the highest overall removal efficiencies of 69 % for peat (biotic control) and 59 % for fill (Fenton's reagent) were partially explained by changes in contaminant soil properties upon oxidation. Molecular analysis of 16S rRNA and alkane monooxygenase (alkB) gene abundances indicated that oxidation with Fenton's reagent and modified Fenton's reagent negatively affected microbial abundance. However, regeneration occurred, and final relative alkB abundances were 1-2 orders of magnitude higher in chemically treated microcosms than in the biotic control. 16S rRNA gene fragment fingerprinting with DGGE and prominent band sequencing illuminated microbial community composition and diversity differences between treatments and identified a variety of phylotypes within Alpha-, Beta-, and Gammaproteobacteria. Understanding microbial community dynamics during coupled chemical oxidation and bioremediation is integral to improved biphasic field application.

Oxide Thin-Film Electronics using All-MXene Electrical Contacts

KAUST Repository

Wang, Zhenwei

2018-02-23

2D MXenes have shown great promise in electrochemical and electromagnetic shielding applications. However, their potential use in electronic devices is significantly less explored. The unique combination of metallic conductivity and hydrophilic surface suggests that MXenes can also be promising in electronics and sensing applications. Here, it is shown that metallic Ti3C2 MXene with work function of 4.60 eV can make good electrical contact with both zinc oxide (ZnO) and tin monoxide (SnO) semiconductors, with negligible band offsets. Consequently, both n-type ZnO and p-type SnO thin-film transistors (TFTs) have been fabricated entirely using large-area MXene (Ti3C2) electrical contacts, including gate, source, and drain. The n- and p-type TFTs show balanced performance, including field-effect mobilities of 2.61 and 2.01 cm2 V−1 s−1 and switching ratios of 3.6 × 106 and 1.1 × 103, respectively. Further, complementary metal oxide semiconductor (CMOS) inverters are demonstrated. The CMOS inverters show large voltage gain of 80 and excellent noise margin of 3.54 V, which is 70.8% of the ideal value. Moreover, the operation of CMOS inverters is shown to be very stable under a 100 Hz square waveform input. The current results suggest that MXene (Ti3C2) can play an important role as contact material in nanoelectronics.

Ferrocene-Functionalized Graphene Oxide Nanosheets: Efficient Electronic Communication between Ferrocene Centers across Graphene Nanosheets

International Nuclear Information System (INIS)

Lu, Yizhong; Jiang, Yuanyuan; Wu, Haibin; Chen, Wei

2015-01-01

Highlights: • Graphene oxide (GO) nanosheets functionalized with ferrocenyl moieties (GO-Fc) are fabricated. • GO-Fc shows efficient electronic communication between ferrocene centers. • GO-Fc exhibits two pairs of voltammetric peaks with a large potential spacing of 0.515 V. • GO-Fc shows a broad absorption peak in the near-infrared range (∼ 1428 nm) at mixed valence. - Abstract: Graphene oxide (GO) nanosheets functionalized with ferrocenyl moieties (GO-Fc) were fabricated through strong covalent C−C bonds. The resulting hybrid showed efficient electronic communication between ferrocene centers due to the strong electron delocalization facilitated by the large pi-pi conjugated structure of graphene sheets. The obtained hybrid exhibited two pairs of voltammetric peaks with a large potential spacing of 0.515 V and a broad absorption peak in the near-infrared range (∼ 1428 nm) at mixed valence. The electrochemical and near IR spectroscopic features suggested a Class II/III behavior of the intervalence charge transfer. This work indicates clearly that strong electronic coupling between ferrocene centers can be easily realized across graphene nanosheets with sp 2 -hybridized carbon

Tuning of electronic properties and dynamical stability of graphene oxide with different functional groups

Science.gov (United States)

Dabhi, Shweta D.; Jha, Prafulla K.

2017-09-01

The structural, electronic and vibrational properties of graphene oxide (GO) with varying proportion of epoxy and hydroxyl functional groups have been studied using density functional theory. The functional groups and oxygen density have an obvious influence on the electronic and vibrational properties. The dependence of band gap on associated functional groups and oxygen density shows a possibility of tuning the band gap of graphene by varying the functional groups as well as oxidation level. The absorption of high oxygen content in graphene leads to the gap opening and resulting in a transition from semimetal to semiconductor. Phonon dispersion curves show no imaginary frequency or no softening of any phonon mode throughout the Brillouin zone which confirms the dynamical stability of all considered GO models. Different groups and different oxygen density result into the varying characteristics of phonon modes. The computed results show good agreement with the experimental observations. Our results present interesting possibilities for engineering the electronic properties of graphene and GO and impact the fabrication of new electronics.

Preparation process and properties of LiCoO{sub 2}/PANI/dodecylbenzenesulfonate composite electrode materials

Energy Technology Data Exchange (ETDEWEB)

Ferchichi, Karima, E-mail: ferchichikarima1@gmail.com [UR Physico-Chimie des Matériaux Solides, Faculté des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia); Hbaieb, Souhaira, E-mail: souhaira.bouchaira@gmail.com [UR Physico-Chimie des Matériaux Solides, Faculté des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia); Amdouni, Noureddine, E-mail: nouredin.amdouni@fst.rnu.tn [UR Physico-Chimie des Matériaux Solides, Faculté des Sciences de Tunis, Manar II, 2092 Tunis (Tunisia); Kalfat, Rafik, E-mail: rafik.kalfat@gmail.com [Institut National de Recherche et d' Analyse Physico-Chimique, 2020 Sidi Thabet (Tunisia); Chevalier, Yves, E-mail: chevalier@lagep.univ-lyon1.fr [Laboratoire d' Automatique et de Génie des Procédés (LAGEP), CNRS UMR 5007, Université Claude Bernard Lyon 1, 69622 Villeurbanne (France)

2013-10-01

Composite materials that combine the lithium exchanging material LiCoO{sub 2} and the conductive polymer poly(aniline) (PANI) have been investigated regarding their possible application to electrode materials of lithium batteries. Such composite materials have been prepared by means of polymerization of aniline in acidic suspensions of LiCoO{sub 2} particles. PANI was synthesized by oxidative polymerization of aniline by ammonium persulfate in the presence of sodium dodecylbenzenesulfonate (SDBS) as a micellar template and dopant. The composite material consisted in LiCoO{sub 2} particles dispersed in a continuous matrix of PANI. The ribbon-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The conductive material had conductivity close to that of PANI because the LiCoO{sub 2} content of the composite material was low. The presence of the poorly conductive inorganic phase caused a significant loss of conductivity, showing that LiCoO{sub 2} blocked electronic transfers between PANI crystallites. Ammonium persulfate caused the loss of lithium from LiCoO{sub 2} when it was used at high concentration in the polymerization recipe. In this case a new phase made of Co{sub 3}O{sub 4} formed by chemical decomposition of Li{sub x}CoO{sub 2}. Thin films prepared from stable suspensions of composite materials in water show comparable electrical performance to that measured for bulk materials. - Highlights: • LiCoO{sub 2} was incorporated in a conductive polymer matrix made of PANI. • The hybrid material retained the high conductive properties of PANI. • Loss of lithium by persulfate oxidation caused conversion of LiCoO{sub 2} into Co{sub 3}O{sub 4}.

From chemolithoautotrophs to electrolithoautotrophs: CO2 fixation by Fe(II)-oxidizing bacteria coupled with direct uptake of electrons from solid electron sources.

Science.gov (United States)

Ishii, Takumi; Kawaichi, Satoshi; Nakagawa, Hirotaka; Hashimoto, Kazuhito; Nakamura, Ryuhei

2015-01-01

At deep-sea vent systems, hydrothermal emissions rich in reductive chemicals replace solar energy as fuels to support microbial carbon assimilation. Until recently, all the microbial components at vent systems have been assumed to be fostered by the primary production of chemolithoautotrophs; however, both the laboratory and on-site studies demonstrated electrical current generation at vent systems and have suggested that a portion of microbial carbon assimilation is stimulated by the direct uptake of electrons from electrically conductive minerals. Here we show that chemolithoautotrophic Fe(II)-oxidizing bacterium, Acidithiobacillus ferrooxidans, switches the electron source for carbon assimilation from diffusible Fe(2+) ions to an electrode under the condition that electrical current is the only source of energy and electrons. Site-specific marking of a cytochrome aa3 complex (aa3 complex) and a cytochrome bc1 complex (bc1 complex) in viable cells demonstrated that the electrons taken directly from an electrode are used for O2 reduction via a down-hill pathway, which generates proton motive force that is used for pushing the electrons to NAD(+) through a bc1 complex. Activation of carbon dioxide fixation by a direct electron uptake was also confirmed by the clear potential dependency of cell growth. These results reveal a previously unknown bioenergetic versatility of Fe(II)-oxidizing bacteria to use solid electron sources and will help with understanding carbon assimilation of microbial components living in electronically conductive chimney habitats.

Magnetic, thermal and luminescence properties in room-temperature nanosecond electron-irradiated various metal oxide nanopowders

Science.gov (United States)

Sokovnin, S. Yu; Balezin, M. E.; Il’ves, V. G.

2018-03-01

By means of pulsed electron beam evaporation in vacuum of targets non-magnetic, in bulk state, Al2O3 and YSZ (ZrO2-8% Y2O3) oxides, magnetic nanopowders (NPs) with a high specific surface were produced. The NPs were subsequently irradiated in air by electrons with energy of 700 keV, using a URT-1 accelerator for 15 and 30 minutes. The magnetic, thermal, and pulsed cathodoluminescence (PCL) characteristics of NPs were measured before and after irradiation. It was established that the electron irradiation non-monotonically changes the magnetization of the pristine samples. To the contrary, a clear correlation between the intensity of PCL and the irradiation doses is found in the oxides. There was a decrease in the intensity of PCL after irradiation. Luminescent and thermal properties reflect the transformation of structural defects in NPs more strongly after the exposure to a pulsed electron beam in comparison with corresponding changes of the NPs magnetic response.

On the nature of organic and inorganic centers that bifurcate electrons, coupling exergonic and endergonic oxidation-reduction reactions.

Science.gov (United States)

Peters, John W; Beratan, David N; Schut, Gerrit J; Adams, Michael W W

2018-04-19

Bifurcating electrons to couple endergonic and exergonic electron-transfer reactions has been shown to have a key role in energy conserving redox enzymes. Bifurcating enzymes require a redox center that is capable of directing electron transport along two spatially separate pathways. Research into the nature of electron bifurcating sites indicates that one of the keys is the formation of a low potential oxidation state to satisfy the energetics required of the endergonic half reaction, indicating that any redox center (organic or inorganic) that can exist in multiple oxidation states with sufficiently separated redox potentials should be capable of electron bifurcation. In this Feature Article, we explore a paradigm for bifurcating electrons down independent high and low potential pathways, and describe redox cofactors that have been demonstrated or implicated in driving this unique biochemistry.

A novel method for qualitative analysis of edible oil oxidation using an electronic nose.

Science.gov (United States)

Xu, Lirong; Yu, Xiuzhu; Liu, Lei; Zhang, Rui

2016-07-01

An electronic nose (E-nose) was used for rapid assessment of the degree of oxidation in edible oils. Peroxide and acid values of edible oil samples were analyzed using data obtained by the American Oil Chemists' Society (AOCS) Official Method for reference. Qualitative discrimination between non-oxidized and oxidized oils was conducted using the E-nose technique developed in combination with cluster analysis (CA), principal component analysis (PCA), and linear discriminant analysis (LDA). The results from CA, PCA and LDA indicated that the E-nose technique could be used for differentiation of non-oxidized and oxidized oils. LDA produced slightly better results than CA and PCA. The proposed approach can be used as an alternative to AOCS Official Method as an innovative tool for rapid detection of edible oil oxidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microfabrication of passive electronic components with printed graphene-oxide deposition

Science.gov (United States)

Sinar, Dogan; Knopf, George K.; Nikumb, Suwas

2014-03-01

Flexible electronic circuitry is an emerging technology that will significantly impact the future of healthcare and medicine, food safety inspection, environmental monitoring, and public security. Recent advances in drop-on-demand printing technology and electrically conductive inks have enabled simple electronic circuits to be fabricated on mechanically flexible polymers, paper, and bioresorbable silk. Research has shown that graphene, and its derivative formulations, can be used to create low-cost electrically conductive inks. Graphene is a one atom thick two-dimensional layer composed of carbon atoms arranged in a hexagonal lattice forming a material with very high fracture strength, high Young's Modulus, and low electrical resistance. Non-conductive graphene-oxide (GO) inks can also be synthesized from inexpensive graphite powders. Once deposited on the flexible substrate the electrical conductivity of the printed GO microcircuit traces can be restored through thermal reduction. In this paper, a femtosecond laser with a wavelength of 775nm and pulse width of 120fs is used to transform the non-conductive printed GO film into electrically conductive oxygen reduced graphene-oxide (rGO) passive electronic components by the process of laser assisted thermal reduction. The heat affected zone produced during the process was minimized because of the femtosecond pulsed laser. The degree of conductivity exhibited by the microstructure is directly related to the laser power level and exposure time. Although rGO films have higher resistances than pristine graphene, the ability to inkjet print capacitive elements and modify local resistive properties provides for a new method of fabricating sensor microcircuits on a variety of substrate surfaces.

Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

KAUST Repository

Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A.; Anthopoulos, Thomas D.

2017-01-01

with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors

Degradation of atenolol via heterogeneous activation of persulfate by using BiOCl@Fe3O4 catalyst under simulated solar light irradiation.

Science.gov (United States)

Shi, Yahong; Chen, Hongche; Wu, Yanlin; Dong, Wenbo

2018-01-01

Efficient oxidative degradation of pharmaceutical pollutants in aquatic environments is of great importance. This study used magnetic BiOCl@Fe 3 O 4 catalyst to activate persulfate (PS) under simulated solar light irradiation. This degradation system was evaluated using atenolol (ATL) as target pollutant. Four reactive species were identified in the sunlight/BiOCl@Fe 3 O 4 /PS system. The decreasing order of the contribution of each reactive species on ATL degradation was as follows: h +  ≈ HO ·  > O 2 ·-  > SO 4 ·- . pH significantly influenced ATL degradation, and an acidic condition favored the reaction. High degradation efficiencies were obtained at pH 2.3-5.5. ATL degradation rate increased with increased catalyst and PS contents. Moreover, ATL mineralization was higher in the sunlight/BiOCl@Fe 3 O 4 /PS system than in the sunlight/BiOCl@Fe 3 O 4 or sunlight/PS system. Nine possible intermediate products were identified through LC-MS analysis, and a degradation pathway for ATL was proposed. The BiOCl@Fe 3 O 4 nanomagnetic composite catalyst was synthesized in this work. This catalyst was easily separated and recovered from a treated solution by using a magnet, and it demonstrated a high catalytic activity. Increased amount of the BiOCl@Fe 3 O 4 catalyst obviously accelerated the efficiency of ATL degradation, and the reusability of the catalyst allowed the addition of a large dosage of BiOCl@Fe 3 O 4 to improve the degradation efficiency.

Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

KAUST Repository

Ali, Haider

2017-08-15

In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21.6% obtained on n-type cells, featuring SiO2/TiO2/Al rear contacts and after forming gas annealing (FGA) at 350°C, is due to strong surface passivation of SiO2/TiO2 stack as well as low contact resistivity at the Si/SiO2/TiO2 heterojunction. This can be attributed to the transformation of amorphous TiO2 to a conducting TiO2-x phase. Conversely, the low efficiency (9.8%) obtained on cells featuring an a-Si:H/TiO2/Al rear contact is due to severe degradation of passivation of the a-Si:H upon FGA.

Two nitro derivatives of azabenzo[a]pyrene N-oxide: Electronic properties and their relation to mutagenic activity

Energy Technology Data Exchange (ETDEWEB)

Ostojić, Bojana D., E-mail: bostojic@chem.bg.ac.rs; Đorđević, Dragana S.

2015-03-21

Highlights: • Molecular properties of nitro isomers of azabenzo[a]pyrene N-oxide are investigated. • Stability, ionization potential, electron affinity, and polarizability are determined. • High quality DFT methods are employed. • Nitroreduction, oxidation, and polarizability are not crucial for mutagenicity. • Dipole moment and electronic charge distribution are important for characterization. - Abstract: The equilibrium geometries, relative energies, IR and Raman spectra, vertical ionization potentials (IP), vertical electron affinities (EA), dipole moments (μ), electronic dipole polarizabilities (α), and molecular electrostatic potentials (MEP) of two species that show very high mutagenicity, 1-nitro-6-azabenzo[a]pyrene N-oxide (1-N-6-ABPO) and 3-nitro-6-azabenzo[a]pyrene N-oxide (3-N-6-ABPO), are investigated by means of Density Functional Theory (DFT) using B3LYP functional with different basis sets. The 3-N-6-ABPO isomer was estimated to be much more mutagenic in Salmonella typhimurium tester strain TA98 (396 000 revertants/nmol) than 1-N-6-ABPO (36 100 revertants/nmol) (Fukuhara et al., 1992). The results show that for both isomers the structural, energetic, and vibrational properties are similar. The orientation of the nitro group with respect to the plane of the aromatic system as well as the nitroreduction and oxidation reaction and polarizability seem not be important for the determination of different mutagenic behavior of these isomers. However, the dipole moment of 3-N-6-ABPO is about 3 times that of 1-N-6-ABPO. The larger dipole moment and the different electronic charge distribution of 3-N-6-ABPO compared to 1-N-6-ABPO imply stronger electrostatic and inductive molecular interactions so that the active site of the enzyme involved in the mutagenic activation can more effectively bind 3-N-6-ABPO compared to 1-N-6-ABPO.

Tuning the Electronic Structure of Titanium Oxide Support to Enhance the Electrochemical Activity of Platinum Nanoparticles

KAUST Repository

Shi, Feifei

2013-09-11

Two times higher activity and three times higher stability in methanol oxidation reaction, a 0.12 V negative shift of the CO oxidation peak potential, and a 0.07 V positive shift of the oxygen reaction potential compared to Pt nanoparticles on pristine TiO2 support were achieved by tuning the electronic structure of the titanium oxide support of Pt nanoparticle catalysts. This was accomplished by adding oxygen vacancies or doping with fluorine. Experimental trends are interpreted in the context of an electronic structure model, showing an improvement in electrochemical activity when the Fermi level of the support material in Pt/TiOx systems is close to the Pt Fermi level and the redox potential of the reaction. The present approach provides guidance for the selection of the support material of Pt/TiOx systems and may be applied to other metal-oxide support materials, thus having direct implications in the design and optimization of fuel cell catalyst supports. © 2013 American Chemical Society.

Localized and collectivized behaviour of d-electrons in complicated titanium, vanadium and niobium oxides

International Nuclear Information System (INIS)

Bazuev, G.V.; Shvejkin, G.P.

1980-01-01

On the basis of investigation of electric and magnetic properties of oxide compounds of transition metals made are the conclusions on the degree of localization and delocalization of d-electrons in them. Generalized are the investigation results of complicated titanium, vanadium, niobium oxide compounds in low degrees of oxidation with rare earth and alkaline earth elements belonging to the two structural types: perovskite and pyrochlore. Presented are the results of investigations of perovskite-like solid solutions and of variable-content phases containing cations of transition metals in two different oxidation degrees: oxide niobium bronzes of two-valent europium and titanium bronzes of rare-earth elements, as well as Lnsub(1-x)Msub(x)Vsub(1-x)sup(3+)Vsub(x)sup(4+)Osub(3), where M is an alkaline earth element

Graphene Oxide-TiO2 Nanocomposite Films for Electron Transport Applications

Science.gov (United States)

Saleem, Abida; Ullah, Naveed; Khursheed, Kamran; Iqbal, Tahir; Shah, Saqlain A.; Asjad, Muhammad; Sarwar, Nazim; Saleem, Murtaza; Arshad, Muhammad

2018-03-01

Graphene oxide-titanium dioxide (GO-TiO2) nanocomposite thin films were prepared for application as the window layer of perovskite solar cells. Graphene oxide (GO) was prepared by a modified Hummer's method, and titanium dioxide (TiO2) nanoparticles were synthesized by hydrothermal solution method. Thin films of GO-TiO2 nanocomposite were prepared with different wt.% of GO by spin coating on indium tin oxide (ITO) substrate followed by annealing at 150°C. X-ray diffraction analysis revealed rutile phase of TiO2 nanostructures. The bandgap of the pure TiO2 thin film was found to be 3.5 eV, reducing to 2.9 eV for the GO-TiO2 nanocomposites with a red-shift towards higher wavelength. Furthermore, thermal postannealing at 400°C improved the transparency in the visible region and decreased the sheet resistance. Morphological and elemental analysis was performed by scanning electron microscopy and energy-dispersive x-ray spectroscopy, respectively. The current-voltage characteristic of the GO-TiO2 nanocomposites indicated Ohmic contact with the ITO substrate. The chemical composition of the as-synthesized GO-TiO2 nanocomposites was investigated by x-ray photoelectron spectroscopy (XPS). The results presented herein demonstrate a new, low-temperature solution-processing approach to obtain rGO-TiO2 composite material for use as the electron transport layer of perovskite solar cells.

Low-voltage protonic/electronic hybrid indium zinc oxide synaptic transistors on paper substrates

International Nuclear Information System (INIS)

Wu, Guodong; Wan, Changjin; Wan, Qing; Zhou, Jumei; Zhu, Liqiang

2014-01-01

Low-voltage (1.5 V) indium zinc oxide (IZO)-based electric-double-layer (EDL) thin-film transistors (TFTs) gated by nanogranular proton conducting SiO 2 electrolyte films are fabricated on paper substrates. Both enhancement-mode and depletion-mode operation are obtained by tuning the thickness of the IZO channel layer. Furthermore, such flexible IZO protonic/electronic hybrid EDL TFTs can be used as artificial synapses, and synaptic stimulation response and short-term synaptic plasticity function are demonstrated. The protonic/electronic hybrid EDL TFTs on paper substrates proposed here are promising for low-power flexible paper electronics, artificial synapses and bioelectronics. (paper)

Electronic devices containing switchably conductive silicon oxides as a switching element and methods for production and use thereof

Science.gov (United States)

Tour, James M; Yao, Jun; Natelson, Douglas; Zhong, Lin; He, Tao

2013-11-26

In various embodiments, electronic devices containing switchably conductive silicon oxide as a switching element are described herein. The electronic devices are two-terminal devices containing a first electrical contact and a second electrical contact in which at least one of the first electrical contact or the second electrical contact is deposed on a substrate to define a gap region therebetween. A switching layer containing a switchably conductive silicon oxide resides in the the gap region between the first electical contact and the second electrical contact. The electronic devices exhibit hysteretic current versus voltage properties, enabling their use in switching and memory applications. Methods for configuring, operating and constructing the electronic devices are also presented herein.

Effects of soluble flavin on heterogeneous electron transfer between surface-exposed bacterial cytochromes and iron oxides

Energy Technology Data Exchange (ETDEWEB)

Wang, Zheming; Shi, Zhi; Shi, Liang; White, Gaye F.; Richardson, David J.; Clarke, Thomas A.; Fredrickson, Jim K.; Zachara, John M.

2015-08-25

Dissimilatory iron-reducing bacteria can utilize insoluble Fe(Mn)-oxides as a terminal electron acceptor under anaerobic conditions. For Shewanella species specifically, some evidence suggests that iron reduction is associated with the secretion of flavin mononucleotide (FMN) and riboflavin that are proposed to mediate electron transfer (Marsili et al., 2008). In this work, we used methyl viologen (MV•+)-encapsulated, porin-cytochrome complex (MtrCAB) embedded liposomes (MELs) as a synthetic model of the Shewanella outer membrane to investigate the proposed mediating behavior of secreted flavins. The reduction kinetics of goethite, hematite and lepidocrocite (200 µM) by MELs ([MV•+] ~ 42 µM and MtrABC ≤ 1 nM) were determined in the presence FMN at pH 7.0 in N2 atmosphere by monitoring the concentrations of MV•+ and FMN through their characteristic UV-visible absorption spectra. Experiments were performed where i) FMN and Fe(III)-oxide were mixed and then reacted with the reduced MELs and ii) FMN was reacted with the reduced MELs followed by addition of Fe(III)-oxide. The redox reactions proceeded in two steps: a fast step that was completed in a few seconds, and a slower one lasting over 400 seconds. For all three Fe(III)-oxides, the initial reaction rate in the presence of a low concentration of FMN (≤ 1 µM) was at least a factor of five faster than those with MELs alone, and orders of magnitude faster than those by FMNH2, suggesting that FMN may serve as a co-factor that enhances electron transfer from outer-membrane c-cytochromes to Fe(III)-oxides. The rate and extent of the initial reaction followed the order of lepidocrocite > hematite > goethite, the same as their reduction potentials, implying thermodynamic control on reaction rate. However, at higher FMN concentrations (> 1 µM), the reaction rates for both steps decreased and varied inversely with FMN concentration, indicating that FMN inhibited the MEL to Fe(III)-oxide electron transfer

A comprehensible need of zinc oxide varistors in electronics technology

International Nuclear Information System (INIS)

Mehmood, F.S.

2007-01-01

A range of varistors, in terms of break down voltage, is required to protect integrated circuits, automotive systems and other modern electronics against transient over-voltages. There is a progressing need for the development and advancement of rugged and reliable varistor capable and proficient of working in harsh and callous environment like automotive Industry where greater than before use of electronics technology has led to improvements in equipment performance and presentation. There is a comprehensible need to combine triumphant and successable models developed at different length scales into an integrated framework that can be used to drive new research and guide experimental efforts and device development. The review of ZnO varistor in particular and metal-oxide varistors (MOVs) in general is presented In this article. (author)

METAL OXIDE DOPED ANTIBACTERIAL POLYMERIC COATED TEXTILE MATERIALS AND ASSESSEMENT OF ANTIBACTERIAL ACTIVITY WITH ELECTRON SPIN RESONANCE

Directory of Open Access Journals (Sweden)

GEDIK Gorkem

2017-05-01

Full Text Available Antibacterial activity of a food conveyor belt is an essential property in some cases. However, every antibacterial chemical is not suitable to contact with food materials. Many metal oxides are suitable option for this purpose. The aim of this study was to investigate antibacterial properties of zinc oxide doped PVC polymer coated with electron spin resonance technique. Therefore, optimum zinc oxide containing PVC paste was prepared and applied to textile surface. Coating construction was designed as double layered, first layer did not contain antibacterial agent, thin second layer contained zinc oxide at 10-35% concentration. Oxygen radicals released from zinc oxide containing polymeric coated surface were spin trapped with DMPO (dimethylpyrroline-N-oxide spin trap and measured with Electron Spin Resonance (ESR. Besides conveyor belt samples, oxygen radical release from zinc oxide surface was measured with ESR under UV light and dark conditions. Oxygen radical release was determined even at dark conditions. Antibacterial properties were tested with ISO 22196 standard using Listeria innocua species. Measured antibacterial properties were related with ESR results. Higher concentration of zinc oxide resulted in higher antibacterial efficiency. DCFH-DA flourometric assay was carried out to determine oxidative stress insidebacteria. It is tought that, this technique will lead to decrease on the labour and time needed for conventional antibacterial tests.

Pulse radiolysis study of one electron oxidation of riboflavin

International Nuclear Information System (INIS)

Kishore, K.; Moorthy, P.N.; Guha, S.N.

1991-01-01

One electron oxidation of riboflavin (Rf) has been studied using various oxidising species such as Cl 2 -. , SO 4 -. and OH radicals. The transient species produced by the reaction of SO 4 -. with riboflavin gave spectra with λ m at 680 and 640 nm at pHs 4 and 7.1 respectively with a pK a at ∼ 6. Cl 2 -. radicals reacted with riboflavin to give a transient spectrum with λ m at 570 nm. The possibility of two sites viz. C-8 methyl group and the extended π-ring system of the molecule for oxidation reaction are discussed. The reaction of Cl 2 -. with riboflavin is an equilibrium from which the redox potential for the Rf +. /Rf couple has been evaluated to be 2.28 V vs NHE. OH radicals reacted with riboflavin to give a transient spectrum attributable to a mixture of species produced by addition or abstraction reactions. (author)

Highly Confined Electronic and Ionic Conduction in Oxide Heterostructures

DEFF Research Database (Denmark)

Pryds, Nini

2015-01-01

The conductance confined at the interface of complex oxide heterostructures provides new opportunities to explore nanoelectronic as well as nanoionic devices. In this talk I will present our recent results both on ionic and electronic conductivity at different heterostructures systems. In the first...... unattainable for Bi2O3-based materials, is achieved[1]. These confined heterostructures provide a playground not only for new high ionic conductivity phenomena that are sufficiently stable but also uncover a large variety of possible technological perspectives. At the second part, I will discuss and show our...

Inverse electron-demand 1,3-dipolar cycloaddition of nitrile oxide with common nitriles leading to 3-functionalized 1,2,4-oxadiazoles.

Science.gov (United States)

Nishiwaki, Nagatoshi; Kobiro, Kazuya; Hirao, Shotaro; Sawayama, Jun; Saigo, Kazuhiko; Ise, Yumiko; Okajima, Yoshikazu; Ariga, Masahiro

2011-10-07

A carbamoyl-substituted nitrile oxide was generated upon treatment of easily available 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with THF (not dried); the reaction proceeded efficiently even in the absence of any special reagents and reaction conditions. The nitrile oxide caused 1,3-dipolar cycloaddition with common aliphatic nitriles or electron-rich aromatic nitriles to afford 3-functionalized 1,2,4-oxadiazoles, which are expected to serve as precursors for the preparation of a variety of functional materials by the chemical transformation of the carbamoyl group. While conventional preparative methods for 1,2,4-oxadiazoles involve the cycloaddition of an electron-rich nitrile oxide with an electron-deficient nitrile or a nitrile activated by a Lewis acid, our method employs the complementary combination of an electron-rich nitrile and an electron-deficient nitrile oxide- the inverse electron-demand 1,3-cycloaddition. The DFT calculations using B3LYP 6-31G* supported the abovementioned inverse reactivity, and also suggested the presence of an accelerating effect by the carbamoyl group as a result of hydrogen bond formation with a dipolarophilic nitrile.

Influence of oxidation treatment on ballistic electron surface-emitting display of porous silicon

International Nuclear Information System (INIS)

Du, Wentao; Zhang, Xiaoning; Zhang, Yujuan; Wang, Wenjiang; Duan, Xiaotao

2012-01-01

Two groups of porous silicon (PS) samples are treated by rapid thermal oxidation (RTO) and electrochemical oxidation (ECO), respectively. Scanning electron microscopy images show that PS samples are segmented into two layers. Oxidized film layer is formed on the top surface of PS samples treated by RTO while at the bottom of PS samples treated by ECO. Both ECO and RTO treatment can make emission current density, diode current density, and emission efficiency of PS increase with the bias voltage increasing. The emission current density and the field emission enhancement factor β of PS sample treated by RTO are larger than that treated by ECO. The Fowler–Nordheim curves of RTO and ECO samples are linear which indicates that high electric field exists on the oxidized layer and field emission occurs whether PS is treated by RTO or ECO.

Electronic States of High-k Oxides in Gate Stack Structures

Science.gov (United States)

Zhu, Chiyu

In this dissertation, in-situ X-ray and ultraviolet photoemission spectroscopy have been employed to study the interface chemistry and electronic structure of potential high-k gate stack materials. In these gate stack materials, HfO2 and La2O3 are selected as high-k dielectrics, VO2 and ZnO serve as potential channel layer materials. The gate stack structures have been prepared using a reactive electron beam system and a plasma enhanced atomic layer deposition system. Three interrelated issues represent the central themes of the research: 1) the interface band alignment, 2) candidate high-k materials, and 3) band bending, internal electric fields, and charge transfer. 1) The most highlighted issue is the band alignment of specific high-k structures. Band alignment relationships were deduced by analysis of XPS and UPS spectra for three different structures: a) HfO2/VO2/SiO2/Si, b) HfO 2-La2O3/ZnO/SiO2/Si, and c) HfO 2/VO2/ HfO2/SiO2/Si. The valence band offset of HfO2/VO2, ZnO/SiO2 and HfO 2/SiO2 are determined to be 3.4 +/- 0.1, 1.5 +/- 0.1, and 0.7 +/- 0.1 eV. The valence band offset between HfO2-La2O3 and ZnO was almost negligible. Two band alignment models, the electron affinity model and the charge neutrality level model, are discussed. The results show the charge neutrality model is preferred to describe these structures. 2) High-k candidate materials were studied through comparison of pure Hf oxide, pure La oxide, and alloyed Hf-La oxide films. An issue with the application of pure HfO2 is crystallization which may increase the leakage current in gate stack structures. An issue with the application of pure La2O3 is the presence of carbon contamination in the film. Our study shows that the alloyed Hf-La oxide films exhibit an amorphous structure along with reduced carbon contamination. 3) Band bending and internal electric fields in the gate stack structure were observed by XPS and UPS and indicate the charge transfer during the growth and process. The oxygen

Investigations of the electronic, magnetic and crystalline structure of perovskite oxides and an oxide-oxide interface

International Nuclear Information System (INIS)

Raisch, Christoph Werner

2013-01-01

Strontium doped LSMO, Calcium doped LCMO and undoped LMO are discussed in chapter 7. The focus lies on a multi-technique approach to correlate changes of one parameter to its effects on others. The characterization of a YBCO / LCMO heterostructure on STO concludes this work (chapter 8). Again it is the electronic, magnetic and crystalline structure at the interface that proves crucial for the properties of this unusual system which artificially combines a superconductor (SC) and a ferromagnet (FM). This structure makes two antagonistic effects meet, the tendency of a superconductor to pair two electrons with different spin into Cooper pairs and the tendency of a ferromagnet to align all spin moments. This fascinating competition shows the wide range of properties that the perovskite oxides offer when they are used accordingly and combined usefully. The above mentioned polar discontinuity at the interface between a manganite and a cuprate is examined. The thesis is completed by a summary and an outlook.

Two-Dimensional Electron Gas at SrTiO3-Based Oxide Heterostructures via Atomic Layer Deposition

Directory of Open Access Journals (Sweden)

Sang Woon Lee

2016-01-01

Full Text Available Two-dimensional electron gas (2DEG at an oxide interface has been attracting considerable attention for physics research and nanoelectronic applications. Early studies reported the formation of 2DEG at semiconductor interfaces (e.g., AlGaAs/GaAs heterostructures with interesting electrical properties such as high electron mobility. Besides 2DEG formation at semiconductor junctions, 2DEG was realized at the interface of an oxide heterostructure such as the LaAlO3/SrTiO3 (LAO/STO heterojunction. The origin of 2DEG was attributed to the well-known “polar catastrophe” mechanism in oxide heterostructures, which consist of an epitaxial LAO layer on a single crystalline STO substrate among proposed mechanisms. Recently, it was reported that the creation of 2DEG was achieved using the atomic layer deposition (ALD technique, which opens new functionality of ALD in emerging nanoelectronics. This review is focused on the origin of 2DEG at oxide heterostructures using the ALD process. In particular, it addresses the origin of 2DEG at oxide interfaces based on an alternative mechanism (i.e., oxygen vacancies.

Structural, electronic structure and antibacterial properties of graphene-oxide nano-sheets

Science.gov (United States)

Sharma, Aditya; Varshney, Mayora; Nanda, Sitansu Sekhar; Shin, Hyun Joon; Kim, Namdong; Yi, Dong Kee; Chae, Keun-Hwa; Ok Won, Sung

2018-04-01

Correlation between the structural/electronic structure properties and bio-activity of graphene-based materials need to be thoroughly evaluated before their commercial implementation in the health and environment precincts. To better investigate the local hybridization of sp2/sp3 orbitals of the functional groups of graphene-oxide (GO) and their execution in the antimicrobial mechanism, we exemplify the antibacterial activity of GO sheets towards the Escherichia coli bacteria (E. coli) by applying the field-emission scanning electron microscopy (FESEM), near edge X-ray absorption fine structure (NEXAFS) and scanning transmission X-ray microscope (STXM) techniques. C K-edge and O K-edge NEXAFS spectra have revealed lesser sp2 carbon atoms in the aromatic ring and attachment of functional oxygen groups at GO sheets. Entrapment of E. coli bacteria by GO sheets is evidenced by FESEM investigations and has also been corroborated by nano-scale imaging of bacteria using the STXM. Spectroscopy evidence of functional oxygen moieties with GO sheets and physiochemical entrapment of E. coli bacteria have assisted us to elaborate the mechanism of cellular oxidative stress-induced disruption of bacterial membrane.

Electron spin resonance characterization of trapping centers in Unibond reg-sign buried oxides

International Nuclear Information System (INIS)

Conley, J.F. Jr.; Lenahan, P.M.; Wallace, B.D.

1996-01-01

Electron spin resonance and capacitance vs. voltage measurements are used to evaluate the radiation response of Unibond buried oxides. When damaged by hole injection, it is found that Unibond reg-sign buried oxides exhibit a rough correspondence between E' centers and positive charge as well as generation of P b centers at the Unibond buried oxide/Si interface. In these respects, Unibond buried oxides qualitatively resemble thermal SiO 2 . However, a hydrogen complexed E' center known as the 74 G doublet is also detected in the Unibond buried oxides. This defect is not detectable in thermal SiO 2 under similar circumstances. Since the presence of 74 G doublet center is generally indicative of very high hydrogen content and since hydrogen is clearly a significant participant in radiation damage, this result suggests a qualitative difference between the radiation response of Unibond and thermal SiO 2 . Unibond results are also compared and contrasted with similar investigations on separation-by-implanted-oxygen (SIMOX) buried oxides. Although the charge trapping response of Unibond buried oxides may be inferior to that of radiation hardened thermal SiO 2 , it appears to be more simple and superior to that of SIMOX buried oxides

Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks

International Nuclear Information System (INIS)

Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Ho, Szu-Han; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Lu, Ching-Sen

2014-01-01

This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO 2 interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks.

A specific 2,4-disubstituted-adamantane interaction with plasma-grown aluminum oxide. Inelastic-electron-tunneling spectroscopy study

NARCIS (Netherlands)

Meijer, E.W.; Raas, M.C.; Velzen, van P.N.T.

1987-01-01

The interaction of several mono- and disubstituted adamantanes with plasma-grown aluminum oxide has been studied using inelastic-electron-tunneling (IET) spectroscopy. The IET spectra evidence the chemisorption of 2,4-adamantanedione onto the aluminum oxide surface as the carboxylate anion of

Hard electronics; Hard electronics

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

Electronic structure of indium-tungsten-oxide alloys and their energy band alignment at the heterojunction to crystalline silicon

Science.gov (United States)

Menzel, Dorothee; Mews, Mathias; Rech, Bernd; Korte, Lars

2018-01-01

The electronic structure of thermally co-evaporated indium-tungsten-oxide films is investigated. The stoichiometry is varied from pure tungsten oxide to pure indium oxide, and the band alignment at the indium-tungsten-oxide/crystalline silicon heterointerface is monitored. Using in-system photoelectron spectroscopy, optical spectroscopy, and surface photovoltage measurements, we show that the work function of indium-tungsten-oxide continuously decreases from 6.3 eV for tungsten oxide to 4.3 eV for indium oxide, with a concomitant decrease in the band bending at the hetero interface to crystalline silicon than indium oxide.

Electrochemical oxidation of amoxicillin in its pharmaceutical formulation at boron doped diamond (BDD electrode

Directory of Open Access Journals (Sweden)

Corneil Quand-Meme Gnamba

2015-08-01

Full Text Available In this work, voltammetric andelectrolysis experiments have been carried out on a conductive boron dopeddiamond (BDD electrode in solution containing amoxicillin in itspharmaceutical formulation. The physical characterization of the BDD surface byscanning electron microscopy (SEM reveals a polycrystalline structure withgrain sizes ranging between 0.3 and 0.6 µm. With Raman spectroscopy, BDDsurface is composed of diamons (Csp3 type carbon (Csp3and graphitic type carbon (Csp2. The electrochemical characterization of the BDD electrode in sulfuric acid electrolyte showed a wide potential window worthing 2.74 V. The oxidation of Amoxicillin showed an irreversible anodic wave on the voltammogram in the domain of water stability indicating a direct oxidation of amoxicillin at BDD surface. The treatment of Amoxicillin in the synthetic wastewaters under various constant current densities 20, 50, 100, 135 mA cm-2 on BDD showed that Amoxicillin is highly reducedunder 100 mA cm-2 reaching 92% of the Chemical Oxygen Demand (CODremoval after 5 h of electrolysis. Investigation performed in perchloric acidas supporting electrolyte led to 87% of COD removal after 5 h of electrolysis.Mineralization of amoxicillin occurs on BDD and the chemical oxygen demandremoval was higher in sulfuric acid than in perchloric acid owing to theinvolvement of the in-situ formed persulfate and perchlorate  to the degradation process mainly in the bulkof the solution. The instantaneous current efficiency (ICE presents anexponential decay indicating that the process was limited by diffusion. Thespecific energy consumed after 5h of the amoxicillin electrolysis was 0.096 kWh COD-1and 0.035 kWh COD-1 in sulfuric acid and in perchloric acidrespectively.

Electron microscopy and EXAFS studies on oxide-supported gold-silver nanoparticles prepared by flame spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Hannemann, Stefan [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland); Grunwaldt, Jan-Dierk [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland)]. E-mail: grunwaldt@chem.ethz.ch; Krumeich, Frank [Laboratory of Inorganic Chemistry, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland); Kappen, Peter [Department of Physics, La Trobe University, Victoria 3086 (Australia); Baiker, Alfons [Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hoenggerberg, CH-8093 Zurich (Switzerland)

2006-09-15

Gold and gold-silver nanoparticles prepared by flame spray pyrolysis (FSP) were characterized by electron microscopy, in situ X-ray absorption spectroscopy (XANES and EXAFS), X-ray diffraction (XRD) and their catalytic activity in CO oxidation. Within this one-step flame-synthesis procedure, precursor solutions of dimethyl gold(III) acetylacetonate and silver(I) benzoate together with the corresponding precursor of the silica, iron oxide or titania support, were sprayed and combusted. In order to prepare small metal particles, a low noble metal loading was required. A loading of 0.1-1 wt.% of Au and Ag resulted in 1-6 nm particles. The size of the noble metal particles increased with higher loadings of gold and particularly silver. Both scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDXS) and X-ray absorption spectroscopy (XAS) studies proved the formation of mixed Au-Ag particles. In case of 1% Au-1% Ag/SiO{sub 2}, TEM combined with electron spectroscopic imaging (ESI) using an imaging filter could be used in addition to prove the presence of silver and gold in the same noble metal particle. CO oxidation in the presence of hydrogen was chosen as a test reaction sensitive to small gold particles. Both the influence of the particle size and the alloying of gold and silver were reflected in the CO oxidation activity.

Electron microscopy and EXAFS studies on oxide-supported gold-silver nanoparticles prepared by flame spray pyrolysis

International Nuclear Information System (INIS)

Hannemann, Stefan; Grunwaldt, Jan-Dierk; Krumeich, Frank; Kappen, Peter; Baiker, Alfons

2006-01-01

Gold and gold-silver nanoparticles prepared by flame spray pyrolysis (FSP) were characterized by electron microscopy, in situ X-ray absorption spectroscopy (XANES and EXAFS), X-ray diffraction (XRD) and their catalytic activity in CO oxidation. Within this one-step flame-synthesis procedure, precursor solutions of dimethyl gold(III) acetylacetonate and silver(I) benzoate together with the corresponding precursor of the silica, iron oxide or titania support, were sprayed and combusted. In order to prepare small metal particles, a low noble metal loading was required. A loading of 0.1-1 wt.% of Au and Ag resulted in 1-6 nm particles. The size of the noble metal particles increased with higher loadings of gold and particularly silver. Both scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDXS) and X-ray absorption spectroscopy (XAS) studies proved the formation of mixed Au-Ag particles. In case of 1% Au-1% Ag/SiO 2 , TEM combined with electron spectroscopic imaging (ESI) using an imaging filter could be used in addition to prove the presence of silver and gold in the same noble metal particle. CO oxidation in the presence of hydrogen was chosen as a test reaction sensitive to small gold particles. Both the influence of the particle size and the alloying of gold and silver were reflected in the CO oxidation activity

Activation of persulfate/copper by hydroxylamine via accelerating the cupric/cuprous redox couple.

Science.gov (United States)

Zhou, Peng; Zhang, Jing; Liang, Juan; Zhang, Yongli; Liu, Ya; Liu, Bei

2016-01-01

Cuprous copper [Cu(I)] reacts with sodium persulfate (PDS) to generate sulfate radical SO4(-)•, but it has been seldom investigated owing to its instability and difficulty in dissolving it. This study proposes a new method to regenerate Cu(I) from cupric copper [Cu(II)] by addition of hydroxylamine (HA) to induce the continuous production of radicals through active PDS, and investigates the resulting enhanced methyl orange (MO) degradation efficiency and mechanism in the new system. HA accelerated the degradation of MO markedly in the pH range from 6.0 to 8.0 in the HA/Cu(II)/PDS process. Both SO4(-)• and hydroxyl radicals (•OH) were considered as the primary reactive radicals in the process. The MO degradation in the HA/Cu(II)/PDS process can be divided into three stages: the fast stage, the transitory stage, and the low stage. MO degradation was enhanced with increased dosage of PDS. Although high dosage of HA could accelerate the transformation of the Cu(II)/Cu(I) cycle to produce more reactive radicals, excess HA can quench the reactive radicals. This study indicates that through a copper-redox cycling mechanism by HA, the production of SO4(-)• and •OH can be strongly enhanced, and the effective pH range can be expanded to neutral conditions.

Correlation between donating or accepting electron behavior of the adsorbed CO or H_2 and its oxidation over TiO_2 under ultraviolet light irradiation

International Nuclear Information System (INIS)

Peng, Xiaoying; He, Zhoujun; Yang, Kai; Chen, Xun; Wang, Xuxu; Dai, Wenxin; Fu, Xianzhi

2016-01-01

Graphical abstract: Although both H_2 and CO can be thermodynamically oxidized by O_2 over TiO_2 under UV irradiation, only CO was oxidized by O_2 over TiO_2 due to its donating electrons to TiO_2, while H_2 was not oxidized by O_2 under the same condition due to its accepting electrons from TiO_2. - Highlights: • CO could but H_2 could not be oxidized over TiO_2 under UV irradiation. • Electron transfer behaviors of species adsorbed at TiO_2 were characterized by gas sensing testing. • Adsorbed CO donated electrons to TiO_2 but adsorbed H_2 accepted electrons from TiO_2 under UV irradiation. • Photocatalytic oxidation of species over TiO_2 maybe depends on the electron transfer direction between species and TiO_2. - Abstract: Although both H_2 and CO can be thermodynamically oxidized by O_2 over TiO_2 under ultraviolet light (UV) irradiation, it was found that CO not H_2 could be oxidized over an anatase TiO_2 in this work. The chemisorption results of CO and H_2 at TiO_2 surface under UV irradiation, investigated by a gas sensing testing, showed that CO adsorption at TiO_2 would cause the decrease of TiO_2 surface impedance, whereas H_2 adsorption would cause its increase. It is proposed that the CO adsorbed at TiO_2 donate electrons to TiO_2 (as a process of CO pre-oxidation), resulting in its oxidation. In contrast, the H_2 adsorbed at TiO_2 accept electrons from TiO_2 (as a process of H_2 pre-reduction), which makes it difficult to be oxidized. This result indicates that the photocatalytic oxidation of a reactant over TiO_2 not only depends on the formation of the photo-generated carriers and the subsequent activated oxidizing species, but maybe also depends on the electron transfer behavior at the interface of the adsorbed reactant and TiO_2.

The electronic and optical properties of warm dense nitrous oxide using quantum molecular dynamics simulations

International Nuclear Information System (INIS)

Zhang Yujuan; Wang Cong; Zhang Ping

2012-01-01

First-principles molecular-dynamics simulations based on density-functional theory have been used to study the electronic and optical properties of fluid nitrous oxide under extreme conditions. Systematic descriptions of pair-correlation function, atomic structure, and the charge density distribution are used to investigate the dissociation of fluid nitrous oxide. The electrical and optical properties are derived from the Kubo-Greenwood formula. It is found that the nonmetal-metal transition for fluid nitrous oxide can be directly associated to the dissociation and has significant influence on the optical properties of the fluid.

A Nanocellulose Polypyrrole Composite Based on Tunicate Cellulose

Directory of Open Access Journals (Sweden)

Dawei Zhang

2013-01-01

Full Text Available The water-dispersed conductive polypyrrole (PPy was prepared via the in situ oxidative chemical polymerization by using ammonium persulfate (APS as oxidant and tunicate cellulose nanocrystals (T-CNs as a dopant and template for tuning the morphologies of PPy nanoparticles. Highly flexible paper-like materials of PPy/T-CNs nanocomposites with high electrical conductivity values and good mechanical properties were prepared. The structure of nanocomposites of PPy/T-CNs was investigated by using Fourier transform infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy analyses of the composites revealed that PPy consisted of nanoparticles about 2.5 nm in mean size to form a continuous coating covered on the T-CNs. The diameters of the PPy nanoparticles increased from 10 to 100 nm with the increasing pyrrole amount. Moreover, electrical properties of the obtained PPy/T-CNs films were studied using standard four-probe technique and the electrical conductivity could be as high as 10−3 S/cm.

Complexes of uranyl with N-oxides of heterocyclic amines. Electron-vibrational absorption spectra

International Nuclear Information System (INIS)

Jezowska-Trzebiatowska, B.; Wieczorek, M.

1977-01-01

A number of coordination compounds formed by uranyl chloride and nitrate with N-oxides of heterocyclic amines have been prepared and characterized by spectral measurements in the absorption region 20000-50000 cm -1 . The electrons and vibronic transitions have been determined and discussed. (author)

Detection of beryllium in oxides and silicates by electron-probe microanalysis

Directory of Open Access Journals (Sweden)

V. V. Khiller

2017-12-01

Full Text Available The author developed the technique of electron-probe microanalysis for quantitative determination of beryllium content, providing the example of studying natural minerals (aluminosilicates and oxides. This technique allowed to obtain a quantitative content of beryllium (in combination with other elements in the emeralds of the Mariinsky beryllium deposit and in zonal mariinskite-chrysoberyl from the chromitites of the Bazhenov ophiolite complex. All analyzes of minerals were performed on a CAMECA SX 100 electron probe microanalyzer with five wave spectrometers (IGG UB RAS. The pressure in the sample chamber was 2 × 10–4 Pa, in the electron gun region – 4 × 10–6 Pa, in wave spectrometers – 7 Pa. Accelerating voltage was 10 kV, the current of absorbed electrons on the Faraday cylinder (beam current was 100–150 nA. Diameter of the electron beam focused on the sample was 2 μm, the angle of x-ray extraction was 40°. The spectra were obtained on wave spectrometers with TAP crystal analyzers (2d = 25.745 Å, LPET (2d = 8.75 Å, LiF (2d = 4.0226 Å, and PC3 (2d = 211.4 Å, a specialized crystal for determining the content of beryllium and boron; the author carried out all the elements measurements along the Kα-lines. To determine position of the analytical peak and the background from two sides with the minimum possible spectral overlap, the author preliminarily recorded spectra on wave spectrometers. The obtained microprobe analyzes of minerals with quantitative determination of beryllium converge well with the available theoretical compositions of beryl and chrysoberyl, which indicates the high efficiency of the developed technique. By using this technique, we can relatively quickly and reliably determine the quantitative content of beryllium in natural silicates and oxides, which is an acute need for geological researchers studying the mineralogy of beryllium deposits.

Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

International Nuclear Information System (INIS)

Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

2016-01-01

Graphical abstract: - Highlights: • Bulk-surface relationship was predicted by the ligand field nature of metal oxides. • Antibonding and bonding d-bands occupancy clarified the bulk-surface relationship. • Different surface relaxations were explained by the bulk electronic structures. • Transition from the bulk to the surface state was simulated by oxygen adsorption. - Abstract: Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO_3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (n_B_u_l_k and n_S_u_r_f) and the adsorption energy of an oxygen atom (E_a_d_s) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the n_B_u_l_k and n_S_u_r_f with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the E_a_d_s on the surfaces was highly correlated with the n_B_u_l_k with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO_3 vs. LaTiO_3). These results suggest that a bulk-derived descriptor such as n_B_u_l_k can be used to screen metal-oxide catalysts.

The effects of electron-hole separation on the photoconductivity of individual metal oxide nanowires

International Nuclear Information System (INIS)

Prades, J D; Hernandez-Ramirez, F; Jimenez-Diaz, R; Manzanares, M; Andreu, T; Cirera, A; Romano-Rodriguez, A; Morante, J R

2008-01-01

The responses of individual ZnO nanowires to UV light demonstrate that the persistent photoconductivity (PPC) state is directly related to the electron-hole separation near the surface. Our results demonstrate that the electrical transport in these nanomaterials is influenced by the surface in two different ways. On the one hand, the effective mobility and the density of free carriers are determined by recombination mechanisms assisted by the oxidizing molecules in air. This phenomenon can also be blocked by surface passivation. On the other hand, the surface built-in potential separates the photogenerated electron-hole pairs and accumulates holes at the surface. After illumination, the charge separation makes the electron-hole recombination difficult and originates PPC. This effect is quickly reverted after increasing either the probing current (self-heating by Joule dissipation) or the oxygen content in air (favouring the surface recombination mechanisms). The model for PPC in individual nanowires presented here illustrates the intrinsic potential of metal oxide nanowires to develop optoelectronic devices or optochemical sensors with better and new performances.

Modification of graphite structure by irradiation, revealed by thermal oxidation. Examination by electronic microscopy

International Nuclear Information System (INIS)

Rouaud, Michel

1969-01-01

Based on the analysis of images obtained by electronic microscopy, this document reports the comparative study of the action of neutrons on three different graphites: a natural one (Ticonderoga) and two pyrolytic ones (Carbone-Lorraine and Raytheon). The approach is based on the modification of features of thermal oxidation of graphites by dry air after irradiation. Different corrosion features are identified. The author states that there seems to be a relationship between the number and shape of these features, and defects existing on the irradiated graphite before oxidation. For low doses, the feature aspect varies with depth at which oxidation occurs. For higher doses, the aspect remains the same [fr

Electrochemical and Electron Paramagnetic Resonance Study of the Mechanism of Oxidation of Phenazine-di-N-oxide in the Presence of Isopropyl alcohol at Glassy Carbon and Single-Walled Carbon Nanotube Electrodes

International Nuclear Information System (INIS)

Kulakovskaya, S.I.; Kulikov, A.V.; Sviridova, L.N.; Stenina, E.V.

2014-01-01

Graphical abstract: - Highlights: • The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied. • The results are explained in terms of the E 1 C 1 E 2 C 2 mechanism of the two-stage electrode process. • The total two-electron catalytic oxidation of i-PrOH in the complex with the phenazine-di-N-oxide radical cation was assumed to occur. - Abstract: The mechanism of oxidation of phenazine-di-N-oxide in the presence of isopropyl alcohol was studied by cyclic voltammetry at glassy carbon (GC) and single-walled carbon nanotubes (SWCNT) electrodes in 0.1 M LiClO 4 solutions in acetonitrile. The adsorption of phenazine-di-N-oxide at SWCNT electrode in 0.1 M LiClO 4 solution in acetonitrile was investigated by measurement of the dependence of the differential double layer capacitance of the electrode C on potential E. The effect of isopropyl alcohol on the shape of cyclic voltammograms (CVs) of phenazine-di-N-oxide and the intensity of Electron Paramagnetic Resonance (EPR) signal of its radical cation was investigated. The catalytic currents were recorded at the oxidation of phenazine-di-N-oxide at SWCNT and GC electrodes in the presence of isopropyl alcohol. The results were explained in terms of the E 1 C 1 E 2 C 2 mechanism of two-stage electrode process characterized by catalytic current recorded at the second electrode stage. The overall two-electron catalytic oxidation of isopropyl alcohol in complex with the phenazine-di-N-oxide radical cation was assumed to occur. It was shown that SWCNT electrodes can be used in the electrocatalytic oxidation of organic compounds in the presence of electrochemically generated phenazine-di-N-oxide radical cation

Studies Of Oxidation And Thermal Reduction Of The Cu(100) Surface Using Positron Annihilation Induced Auger Electron Spectroscopy

Science.gov (United States)

Fazleev, N. G.; Nadesalingam, M. P.; Maddox, W.; Weiss, A. H.

2011-06-01

Positron annihilation induced Auger electron spectroscopy (PAES) measurements from the surface of an oxidized Cu(100) single crystal show a large increase in the intensity of the annihilation induced Cu M2,3VV Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 °C. The PAES intensity then decreases monotonically as the annealing temperature is increased to ˜550 °C. Experimental positron annihilation probabilities with Cu 3p and O 1s core electrons are estimated from the measured intensities of the positron annihilation induced Cu M2,3VV and O KLL Auger transitions. PAES results are analyzed by performing calculations of positron surface states and annihilation probabilities of the surface-trapped positrons with relevant core electrons taking into account the charge redistribution at the surface and various surface structures associated with low and high oxygen coverages. The variations in atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface are found to affect localization and spatial extent of the positron surface state wave function. The computed positron binding energy and annihilation characteristics reveal their sensitivity to charge transfer effects, atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface. Theoretical positron annihilation probabilities with Cu 3p and O 1s core electrons computed for the oxidized Cu(100) surface are compared with experimental ones. The obtained results provide a demonstration of thermal reduction of the copper oxide surface after annealing at 300 °C followed by re-oxidation of the Cu(100) surface at higher annealing temperatures presumably due to diffusion of subsurface oxygen to the surface.

Studies Of Oxidation And Thermal Reduction Of The Cu(100) Surface Using Positron Annihilation Induced Auger Electron Spectroscopy

International Nuclear Information System (INIS)

Fazleev, N. G.; Nadesalingam, M. P.; Maddox, W.; Weiss, A. H.

2011-01-01

Positron annihilation induced Auger electron spectroscopy (PAES) measurements from the surface of an oxidized Cu(100) single crystal show a large increase in the intensity of the annihilation induced Cu M2,3VV Auger peak as the sample is subjected to a series of isochronal anneals in vacuum up to annealing temperature 300 deg. C. The PAES intensity then decreases monotonically as the annealing temperature is increased to ∼550 deg. C. Experimental positron annihilation probabilities with Cu 3p and O 1s core electrons are estimated from the measured intensities of the positron annihilation induced Cu M 2,3 VV and O KLL Auger transitions. PAES results are analyzed by performing calculations of positron surface states and annihilation probabilities of the surface-trapped positrons with relevant core electrons taking into account the charge redistribution at the surface and various surface structures associated with low and high oxygen coverages. The variations in atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface are found to affect localization and spatial extent of the positron surface state wave function. The computed positron binding energy and annihilation characteristics reveal their sensitivity to charge transfer effects, atomic structure and chemical composition of the topmost layers of the oxidized Cu(100) surface. Theoretical positron annihilation probabilities with Cu 3p and O 1s core electrons computed for the oxidized Cu(100) surface are compared with experimental ones. The obtained results provide a demonstration of thermal reduction of the copper oxide surface after annealing at 300 deg. C followed by re-oxidation of the Cu(100) surface at higher annealing temperatures presumably due to diffusion of subsurface oxygen to the surface.

Deep electron traps in HfO_2-based metal-oxide-semiconductor capacitors

International Nuclear Information System (INIS)

Salomone, L. Sambuco; Lipovetzky, J.; Carbonetto, S.H.; García Inza, M.A.; Redin, E.G.; Campabadal, F.

2016-01-01

Hafnium oxide (HfO_2) is currently considered to be a good candidate to take part as a component in charge-trapping nonvolatile memories. In this work, the electric field and time dependences of the electron trapping/detrapping processes are studied through a constant capacitance voltage transient technique on metal-oxide-semiconductor capacitors with atomic layer deposited HfO_2 as insulating layer. A tunneling-based model is proposed to reproduce the experimental results, obtaining fair agreement between experiments and simulations. From the fitting procedure, a band of defects is identified, located in the first 1.7 nm from the Si/HfO_2 interface at an energy level E_t = 1.59 eV below the HfO_2 conduction band edge with density N_t = 1.36 × 10"1"9 cm"−"3. A simplified analytical version of the model is proposed in order to ease the fitting procedure for the low applied voltage case considered in this work. - Highlights: • We characterized deep electron trapping/detrapping in HfO_2 structures. • We modeled the experimental results through a tunneling-based model. • We obtained an electron trap energy level of 1.59 eV below conduction band edge. • We obtained a spatial trap distribution extending 1.7 nm within the insulator. • A simplified tunneling front model is able to reproduce the experimental results.

David Adler Lectureship Award in the Field of Materials Physics Talk: Novel Nitride and Oxide Electronics

Science.gov (United States)

Pearton, Stephen

2011-03-01

Recent progress in development of GaN-based transistors for gas and bio-sensing applications and amorphous IGZO layers for use thin film transistors (TFTs)on flexible substrates, including paper,will be presented. For the detection of gases such as hydrogen, the gateless GaN transistors are typically coated with a catalyst metal such as Pd or Pt to increase the detection sensitivity at room temperature. Functionalizing the surface with oxides, polymers and nitrides is also useful in enhancing the detection sensitivity for gases and ionic solutions.The use of enzymes or adsorbed antibody layers on the semiconductor surface leads to highly specific detection of a broad range of antigens of interest in the medical and security fields. We give examples of recent work showing sensitive detection of glucose, lactic acid, prostate cancer and breast cancer markers and the integration of the sensors with wireless data transmission systems to achieve robust, portable sensors. The amorphous transparent conducting oxide InZnGaO4 (IGZO) is attracting attention because of its high electron mobility (10-50 cm2.V-1.sec-1), high transparency in the visible region of the spectrum and its ability to be deposited with a wide range of conductivities.This raises the possibility of making low-cost electronics on a very wide range of arbitrary surfaces, including paper and plastics. N-type oxides such as zinc oxide, zinc tin oxide, indium gallium oxide, and indium gallium zinc tin oxide (IGZO) exhibit surprisingly high carrier mobilities even for amorphous films deposited at 300K. This has been explained by the fact that the conduction in these materials is predominantly through non-directional s orbitals which are less affected by disorder than the directional sp3 orbitals which control electron transport in Si. Examples of progress and discussion of remaining obstacles to use of IGZO TFTs will be presented Work performed in collaboration with Fan Ren.

Tyrosine oxidation in heme oxygenase: examination of long-range proton-coupled electron transfer.

Science.gov (United States)

Smirnov, Valeriy V; Roth, Justine P

2014-10-01

Heme oxygenase is responsible for the degradation of a histidine-ligated ferric protoporphyrin IX (Por) to biliverdin, CO, and the free ferrous ion. Described here are studies of tyrosyl radical formation reactions that occur after oxidizing Fe(III)(Por) to Fe(IV)=O(Por(·+)) in human heme oxygenase isoform-1 (hHO-1) and the structurally homologous protein from Corynebacterium diphtheriae (cdHO). Site-directed mutagenesis on hHO-1 probes the reduction of Fe(IV)=O(Por(·+)) by tyrosine residues within 11 Å of the prosthetic group. In hHO-1, Y58· is implicated as the most likely site of oxidation, based on the pH and pD dependent kinetics. The absence of solvent deuterium isotope effects in basic solutions of hHO-1 and cdHO contrasts with the behavior of these proteins in the acidic solution, suggesting that long-range proton-coupled electron transfer predominates over electron transfer.

In situ Charge Density Imaging of Metamaterials made with Switchable Two dimensionalElectron Gas at Oxide Heterointerfaces

Science.gov (United States)

2017-11-28

engineering of complex oxide systems. This work has been accepted for publication in Nature Nanotechnology (“Direct Imaging of the Electron Liquid at Oxide...mail address: eom@engr.wisc.edu - Institution: University of Wisconsin-Madison - Mailing Address: 2166 ECB, 1550 Engineering Drive, Madison, WI 53706...Interfaces” K. Song et al., in press, Nature Nanotechnology (2018)) Figure 1. Direct imaging of the 2DELs at oxide interfaces. a, b, 2-D surface

Surface electronic and structural properties of nanostructured titanium oxide grown by pulsed laser deposition

NARCIS (Netherlands)

Fusi, M.; Maccallini, E.; Caruso, T.; Casari, C. S.; Bassi, A. Li; Bottani, C. E.; Rudolf, P.; Prince, K. C.; Agostino, R. G.

Titanium oxide nanostructured thin films synthesized by pulsed laser deposition (PLD) were here characterized with a multi-technique approach to investigate the relation between surface electronic, structural and morphological properties. Depending on the growth parameters, these films present

Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

Science.gov (United States)

Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

2016-06-01

Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

Mathematical modelling of the kinetics of aerosol oxidation of sulfur dioxide upon electron-beam purification of power-plant flue gases from nitrogen and sulfur oxides

International Nuclear Information System (INIS)

Gerasimov, G.Ya.; Gerasimova, T.S.; Fadeev, S.A.

1996-01-01

A kinetic model of SO 2 oxidation in flue gases, irradiated with accelerated electron flux is proposed. The model comprises an optimized mechanism of gas phase radiation chemical oxidation of NO and SO 2 , kinetics circuit of SO 2 and NH 3 thermal interaction, kinetic models of volumetric condensation of water and sulfuric acid vapors and liquid-phase oxidation of SO 2 in aerosol drops, produced in the course of volumetric condensation. Calculation results are in a satisfactory agreement with experimental data. (author)

Highly efficient one-step synthesis of carbon encapsulated nanocrystals by the oxidation of metal π-complexes

Science.gov (United States)

Liu, Boyang; Shao, Yingfeng; Xiang, Xin; Zhang, Fuhua; Yan, Shengchang; Li, Wenge

2017-08-01

Various carbon encapsulated nanocrystals, including MnS and MnO, Cr2O3, MoO2, Fe7S8 and Fe3O4, and ZrO2, are prepared in one step and in situ by a simple and highly efficient synthesis approach. The nanocrystals have an equiaxed morphology and a median size smaller than 30 nm. Tens and hundreds of these nanocrystals are entirely encapsulated by a wormlike amorphous carbon shell. The formation of a core-shell structure depends on the strongly exothermic reaction of metal π-complexes with ammonium persulfate in an autoclave at below 200 °C. During the oxidation process, the generated significant amounts of heat will destroy the molecular structure of the metal π-complex and cleave the ligands into small carbon fragments, which further transform into an amorphous carbon shell. The central metal atoms are oxidized to metal oxide/sulfide nanocrystals. The formation of a core-shell structure is independent of the numbers of ligands and carbon atoms as well as the metal types, implying that any metal π-complex can serve as a precursor and that various carbon encapsulated nanocrystals can be synthesized by this method.

Correlative scanning electron and confocal microscopy imaging of labeled cells coated by indium-tin-oxide

KAUST Repository

Rodighiero, Simona

2015-03-22

Confocal microscopy imaging of cells allows to visualize the presence of specific antigens by using fluorescent tags or fluorescent proteins, with resolution of few hundreds of nanometers, providing their localization in a large field-of-view and the understanding of their cellular function. Conversely, in scanning electron microscopy (SEM), the surface morphology of cells is imaged down to nanometer scale using secondary electrons. Combining both imaging techniques have brought to the correlative light and electron microscopy, contributing to investigate the existing relationships between biological surface structures and functions. Furthermore, in SEM, backscattered electrons (BSE) can image local compositional differences, like those due to nanosized gold particles labeling cellular surface antigens. To perform SEM imaging of cells, they could be grown on conducting substrates, but obtaining images of limited quality. Alternatively, they could be rendered electrically conductive, coating them with a thin metal layer. However, when BSE are collected to detect gold-labeled surface antigens, heavy metals cannot be used as coating material, as they would mask the BSE signal produced by the markers. Cell surface could be then coated with a thin layer of chromium, but this results in a loss of conductivity due to the fast chromium oxidation, if the samples come in contact with air. In order to overcome these major limitations, a thin layer of indium-tin-oxide was deposited by ion-sputtering on gold-decorated HeLa cells and neurons. Indium-tin-oxide was able to provide stable electrical conductivity and preservation of the BSE signal coming from the gold-conjugated markers. © 2015 Wiley Periodicals, Inc.

Chemical dosimetry of linac electron pulse with nitrous oxide

International Nuclear Information System (INIS)

Nanba, Hideki; Shinsaka, Kyoji; Hatano, Yoshihiko; Yagi, Masuo; Shiokawa, Takanobu.

1975-01-01

Absorption dose, dose rate and the reproducibility of intensity in each pulse of the electron beam pulses from a Linac (42 MeV, 3μsec) have been determined by applying nitrous oxide chemical dosimetry, in order to obtain the fundamental data required for radiation chemistry researches with the Linac. Nitrous oxide is used as a chemical dosimeter because it is known that it decomposed through radiation ensures easy detection and the determination of quantity of the decomposed product, nitrogen, which is stable, and presents linear relationship between absorption dose and produced quantity over the wide dose-rate range. Irradiation cells used for the experiment were cylindrical ones made of hard molybdenum glass. Irradiated samples were fractionated with liquid nitrogen, and separated and determined with a gas chromatograph. Details on the experimental results and their examination are described at the end. They include absorption dose of 1x10 16 eV/g per pulse, dose rate of 3x10 21 eV/g, sec and intensity reproducibility of +- 20%. (Wakatsuki, Y.)

Immobilization, hybridization, and oxidation of synthetic DNA on gold surface: Electron transfer investigated by electrochemistry and scanning tunneling microscopy

Energy Technology Data Exchange (ETDEWEB)

McEwen, Gerald D.; Chen Fan [Biological Engineering Program, Department of Biological and Irrigation Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 (United States); Zhou Anhong, E-mail: Anhong.Zhou@usu.edu [Biological Engineering Program, Department of Biological and Irrigation Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322-4105 (United States)

2009-06-08

Fundamental understanding of interfacial electron transfer (ET) among electrolyte/DNA/solid-surface will facilitate the design for electrical detection of DNA molecules. In this report, the electron transfer characteristics of synthetic DNA (sequence from pathogenic Cryptosporidium parvum) self-assembled on a gold surface was electrochemically studied. The effects of immobilization order on the interface ET related parameters such as diffusion coefficient (D{sub 0}), surface coverage ({theta}{sub R}), and monolayer thickness (d{sub i}) were determined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DNA surface density ({Gamma}{sub DNA}) was determined by the integration of the charge of the electro-oxidation current peaks during the initial cyclic voltammetry scans. It was found that the DNA surface densities at different modifications followed the order: {Gamma}{sub DNA} (dsS-DNA/Au) > {Gamma}{sub DNA} (MCH/dsS-DNA/Au) > {Gamma}{sub DNA} (dsS-DNA/MCH/Au). It was also revealed that the electro-oxidation of the DNA modified gold surface would involve the oxidation of nucleotides (guanine and adenine) with a 5.51 electron transfer mechanism and the oxidative desorption of DNA and MCH molecules by a 3 electron transfer mechanism. STM topography and current image analysis indicated that the surface conductivity after each surface modification followed the order: dsS-DNA/Au < MCH/dsS-DNA/Au < oxidized MCH/dsS-DNA/Au < Hoechst/oxidized MCH/dsS-DNA/Au. The results from this study suggested a combination of variations in immobilization order may provide an alternative approach for the optimization of DNA hybridization and the further development for electrical detection of DNA.

Tuning the Electron Gas at an Oxide Heterointerface via Free Surface Charges

Energy Technology Data Exchange (ETDEWEB)

Bell, Christopher

2011-08-11

Oxide heterointerfaces are emerging as one of the most exciting materials systems in condensed matter science. One remarkable example is the LaAlO{sub 3}/SrTiO{sub 3} (LAO/STO) interface, a model system in which a highly mobile electron gas forms between two band insulators, exhibiting two dimensional superconductivity and unusual magnetotransport properties. An ideal tool to tune such an electron gas is the electrostatic field effect. In principle, the electrostatic field can be generated by bound charges due to polarization (as in the normal and ferroelectric field effects) or by adding excess free charge. In previous studies, a large modulation of the carrier density and mobility of the LAO/STO interface has been achieved using the normal field effect. However, little attention has been paid to the field effect generated by free charges. This issue is scarcely addressed, even in conventional semiconductor devices, since the free charges are typically not stable. Here, we demonstrate an unambiguous tuning of the LAO/STO interface conductivity via free surface charges written using conducting atomic force microscopy (AFM). The modulation of the carrier density was found to be reversible, nonvolatile and surprisingly large, {approx}3 x 10{sup 13} cm{sup -2}, comparable to the maximum modulation by the normal field effect. Our finding reveal the efficiency of free charges in controlling the conductivity of this oxide interface, and suggest that this technique may be extended more generally to other oxide systems.

Anaerobic arsenite oxidation with an electrode serving as the sole electron acceptor: A novel approach to the bioremediation of arsenic-polluted groundwater

Energy Technology Data Exchange (ETDEWEB)

Pous, Narcis [Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, C/Maria Aurèlia Capmany, 69 E-17071 Girona (Spain); Casentini, Barbara; Rossetti, Simona; Fazi, Stefano [Water Research Institute (IRSA-CNR), National Research Council, Via Salaria Km 29.300, 00015 Monterotondo (Italy); Puig, Sebastià [Laboratory of Chemical and Environmental Engineering (LEQUiA), Institute of the Environment, University of Girona, C/Maria Aurèlia Capmany, 69 E-17071 Girona (Spain); Aulenta, Federico, E-mail: aulenta@irsa.cnr.it [Water Research Institute (IRSA-CNR), National Research Council, Via Salaria Km 29.300, 00015 Monterotondo (Italy)

2015-02-11

Highlights: • As(III) was oxidized to As(V) in a bioelectrochemical system. • A polarized graphite electrode served as electron acceptor. • Gammaproteobacteria were the dominating organisms at the electrode. - Abstract: Arsenic contamination of soil and groundwater is a serious problem worldwide. Here we show that anaerobic oxidation of As(III) to As(V), a form which is more extensively and stably adsorbed onto metal-oxides, can be achieved by using a polarized (+497 mV vs. SHE) graphite anode serving as terminal electron acceptor in the microbial metabolism. The characterization of the microbial populations at the electrode, by using in situ detection methods, revealed the predominance of gammaproteobacteria. In principle, the proposed bioelectrochemical oxidation process would make it possible to provide As(III)-oxidizing microorganisms with a virtually unlimited, low-cost and low-maintenance electron acceptor as well as with a physical support for microbial attachment.

Anaerobic arsenite oxidation with an electrode serving as the sole electron acceptor: A novel approach to the bioremediation of arsenic-polluted groundwater

International Nuclear Information System (INIS)

Pous, Narcis; Casentini, Barbara; Rossetti, Simona; Fazi, Stefano; Puig, Sebastià; Aulenta, Federico

2015-01-01

Highlights: • As(III) was oxidized to As(V) in a bioelectrochemical system. • A polarized graphite electrode served as electron acceptor. • Gammaproteobacteria were the dominating organisms at the electrode. - Abstract: Arsenic contamination of soil and groundwater is a serious problem worldwide. Here we show that anaerobic oxidation of As(III) to As(V), a form which is more extensively and stably adsorbed onto metal-oxides, can be achieved by using a polarized (+497 mV vs. SHE) graphite anode serving as terminal electron acceptor in the microbial metabolism. The characterization of the microbial populations at the electrode, by using in situ detection methods, revealed the predominance of gammaproteobacteria. In principle, the proposed bioelectrochemical oxidation process would make it possible to provide As(III)-oxidizing microorganisms with a virtually unlimited, low-cost and low-maintenance electron acceptor as well as with a physical support for microbial attachment

Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

Energy Technology Data Exchange (ETDEWEB)

Angermann, Heike, E-mail: angermann@helmholtz-berlin.de

2014-09-01

Highlights: • Determination of electronic interface properties by contact-less surface photovoltage (SPV) technique. • Systematic correlations of substrate morphology and surface electronic properties. • Optimization of surface pre-treatment for flat, saw damage etched, and textured Si solar cell substrates. • Ultra-thin passivating Si oxide layers with low densities of rechargeable states by wet-chemical oxidation and subsequent annealing. • Environmentally acceptable processes, utilizing hot water, diluted HCl, or ozone low cost alternative to current approaches with concentrated chemicals. • The effect of optimized wet-chemical pre-treatments can be preserved during subsequent layer deposition. - Abstract: The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution D{sub it}(E), and density D{sub it,min} of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly

Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

International Nuclear Information System (INIS)

Angermann, Heike

2014-01-01

Highlights: • Determination of electronic interface properties by contact-less surface photovoltage (SPV) technique. • Systematic correlations of substrate morphology and surface electronic properties. • Optimization of surface pre-treatment for flat, saw damage etched, and textured Si solar cell substrates. • Ultra-thin passivating Si oxide layers with low densities of rechargeable states by wet-chemical oxidation and subsequent annealing. • Environmentally acceptable processes, utilizing hot water, diluted HCl, or ozone low cost alternative to current approaches with concentrated chemicals. • The effect of optimized wet-chemical pre-treatments can be preserved during subsequent layer deposition. - Abstract: The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution D it (E), and density D it,min of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly based on

Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide

International Nuclear Information System (INIS)

Marini, Sara; Buonanno, Giorgio; Stabile, Luca; Ficco, Giorgio

2014-01-01

The objective of this study was to compare the short-term respiratory effects due to the inhalation of electronic and conventional tobacco cigarette-generated mainstream aerosols through the measurement of the exhaled nitric oxide (eNO). To this purpose, twenty-five smokers were asked to smoke a conventional cigarette and to vape an electronic cigarette (with and without nicotine), and an electronic cigarette without liquid (control session). Electronic and tobacco cigarette mainstream aerosols were characterized in terms of total particle number concentrations and size distributions. On the basis of the measured total particle number concentrations and size distributions, the average particle doses deposited in alveolar and tracheobronchial regions of the lungs for a single 2-s puff were also estimated considering a subject performing resting (sitting) activity. Total particle number concentrations in the mainstream resulted equal to 3.5 ± 0.4 × 10 9 , 5.1 ± 0.1 × 10 9 , and 3.1 ± 0.6 × 10 9 part. cm −3 for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively. The corresponding alveolar doses for a resting subject were estimated equal to 3.8 × 10 10 , 5.2 × 10 10 and 2.3 × 10 10 particles. The mean eNO variations measured after each smoking/vaping session were equal to 3.2 ppb, 2.7 ppb and 2.8 ppb for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively; whereas, negligible eNO changes were measured in the control session. Statistical tests performed on eNO data showed statistically significant differences between smoking/vaping sessions and the control session, thus confirming a similar effect on human airways whatever the cigarette smoked/vaped, the nicotine content, and the particle dose received. - Highlights: • Electronic cigarettes (with and without nicotine) mainstream aerosols were analyzed; • Particle number concentrations and size distributions

Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide

Energy Technology Data Exchange (ETDEWEB)

Marini, Sara, E-mail: s.marini@unicas.it [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy); Buonanno, Giorgio [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy); Queensland University of Technology, Brisbane (Australia); Stabile, Luca; Ficco, Giorgio [Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino (Italy)

2014-07-01

The objective of this study was to compare the short-term respiratory effects due to the inhalation of electronic and conventional tobacco cigarette-generated mainstream aerosols through the measurement of the exhaled nitric oxide (eNO). To this purpose, twenty-five smokers were asked to smoke a conventional cigarette and to vape an electronic cigarette (with and without nicotine), and an electronic cigarette without liquid (control session). Electronic and tobacco cigarette mainstream aerosols were characterized in terms of total particle number concentrations and size distributions. On the basis of the measured total particle number concentrations and size distributions, the average particle doses deposited in alveolar and tracheobronchial regions of the lungs for a single 2-s puff were also estimated considering a subject performing resting (sitting) activity. Total particle number concentrations in the mainstream resulted equal to 3.5 ± 0.4 × 10{sup 9}, 5.1 ± 0.1 × 10{sup 9}, and 3.1 ± 0.6 × 10{sup 9} part. cm{sup −3} for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively. The corresponding alveolar doses for a resting subject were estimated equal to 3.8 × 10{sup 10}, 5.2 × 10{sup 10} and 2.3 × 10{sup 10} particles. The mean eNO variations measured after each smoking/vaping session were equal to 3.2 ppb, 2.7 ppb and 2.8 ppb for electronic cigarettes without nicotine, with nicotine, and for conventional cigarettes, respectively; whereas, negligible eNO changes were measured in the control session. Statistical tests performed on eNO data showed statistically significant differences between smoking/vaping sessions and the control session, thus confirming a similar effect on human airways whatever the cigarette smoked/vaped, the nicotine content, and the particle dose received. - Highlights: • Electronic cigarettes (with and without nicotine) mainstream aerosols were analyzed; • Particle number

Inductive crystal field control in layered metal oxides with correlated electrons

International Nuclear Information System (INIS)

Balachandran, P. V.; Cammarata, A.; Rondinelli, J. M.; Nelson-Cheeseman, B. B.; Bhattacharya, A.

2014-01-01

We show that the NiO 6 crystal field energies can be tailored indirectly via heterovalent A cation ordering in layered (La,A)NiO 4 Ruddlesden–Popper (RP) oxides, where A = Sr, Ca, or Ba, using density functional calculations. We leverage as a driving force the electrostatic interactions between charged [LaO] 1+ and neutral [AO] 0 planes to inductively tune the Ni–O bond distortions, without intentional doping or epitaxial strain, altering the correlated d-orbital energies. We use this strategy to design cation ordered LaCaNiO 4 and LaBaNiO 4 with distortions favoring enhanced Ni e g orbital polarization, and find local electronic structure signatures analogous to those in RP La-cuprates, i.e., parent phases of the high-temperature superconducting oxides

Design of nanophotonic, hot-electron solar-blind ultraviolet detectors with a metal-oxide-semiconductor structure

International Nuclear Information System (INIS)

Wang, Zhiyuan; Wang, Xiaoxin; Liu, Jifeng

2014-01-01

Solar-blind ultraviolet (UV) detection refers to photon detection specifically in the wavelength range of 200 nm–320 nm. Without background noises from solar radiation, it has broad applications from homeland security to environmental monitoring. The most commonly used solid state devices for this application are wide band gap (WBG) semiconductor photodetectors (Eg > 3.5 eV). However, WBG semiconductors are difficult to grow and integrate with Si readout integrated circuits (ROICs). In this paper, we design a nanophotonic metal-oxide-semiconductor structure on Si for solar-blind UV detectors. Instead of using semiconductors as the active absorber, we use Sn nano-grating structures to absorb UV photons and generate hot electrons for internal photoemission across the Sn/SiO 2 interfacial barrier, thereby generating photocurrent between the metal and the n-type Si region upon UV excitation. Moreover, the transported hot electron has an excess kinetic energy >3 eV, large enough to induce impact ionization and generate another free electron in the conduction band of n-Si. This process doubles the quantum efficiency. On the other hand, the large metal/oxide interfacial energy barrier (>3.5 eV) also enables solar-blind UV detection by blocking the less energetic electrons excited by visible photons. With optimized design, ∼75% UV absorption and hot electron excitation can be achieved within the mean free path of ∼20 nm from the metal/oxide interface. This feature greatly enhances hot electron transport across the interfacial barrier to generate photocurrent. The simple geometry of the Sn nano-gratings and the MOS structure make it easy to fabricate and integrate with Si ROICs compared to existing solar-blind UV detection schemes. The presented device structure also breaks through the conventional notion that photon absorption by metal is always a loss in solid-state photodetectors, and it can potentially be extended to other active metal photonic devices. (paper)

Direct exchange between silicon nanocrystals and tunnel oxide traps under illumination on single electron photodetector

Energy Technology Data Exchange (ETDEWEB)

Chatbouri, S., E-mail: Samir.chatbouri@yahoo.com; Troudi, M.; Sghaier, N.; Kalboussi, A. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Aimez, V. [Université de Sherbrooke, Laboratoire Nanotechnologies et Nanosystémes (UMI-LN2 3463), Université de Sherbrooke—CNRS—INSA de Lyon-ECL-UJF-CPE Lyon, Institut Interdisciplinaire d’Innovation Technologique (Canada); Drouin, D. [Avenue de I’environnement, Université de Monastir, Laboratoire de Micro électronique et Instrumentation (LR13ES12), Faculté des Sciences de Monastir (Tunisia); Souifi, A. [Institut des Nanotechnologies de Lyon—site INSA de Lyon, UMR CNRS 5270 (France)

2016-09-15

In this paper we present the trapping of photogenerated charge carriers for 300 s resulted by their direct exchange under illumination between a few silicon nanocrystals (ncs-Si) embedded in an oxide tunnel layer (SiO{sub x} = 1.5) and the tunnel oxide traps levels for a single electron photodetector (photo-SET or nanopixel). At first place, the presence of a photocurrent limited in the inversion zone under illumination in the I–V curves confirms the creation of a pair electron/hole (e–h) at high energy. This photogenerated charge carriers can be trapped in the oxide. Using the capacitance-voltage under illumination (the photo-CV measurements) we show a hysteresis chargement limited in the inversion area, indicating that the photo-generated charge carriers are stored at traps levels at the interface and within ncs-Si. The direct exchange of the photogenerated charge carriers between the interface traps levels and the ncs-Si contributed on the photomemory effect for 300 s for our nanopixel at room temperature.

Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

International Nuclear Information System (INIS)

Jodon de Villeroche, Suzanne

1968-01-01

The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

High-performance all-printed amorphous oxide FETs and logics with electronically compatible electrode/ channel interface.

Science.gov (United States)

Sharma, Bhupendra Kumar; Stoesser, Anna; Mondal, Sandeep Kumar; Garlapati, Suresh K; Fawey, Mohammed H; Chakravadhanula, Venkata Sai Kiran; Kruk, Robert; Hahn, Horst; Dasgupta, Subho

2018-06-12

Oxide semiconductors typically show superior device performance compared to amorphous silicon or organic counterparts, especially, when they are physical vapor deposited. However, it is not easy to reproduce identical device characteristics when the oxide field-effect transistors (FETs) are solution-processed/ printed; the level of complexity further intensifies with the need to print the passive elements as well. Here, we developed a protocol for designing the most electronically compatible electrode/ channel interface based on the judicious material selection. Exploiting this newly developed fabrication schemes, we are now able to demonstrate high-performance all-printed FETs and logic circuits using amorphous indium-gallium-zinc oxide (a-IGZO) semiconductor, indium tin oxide (ITO) as electrodes and composite solid polymer electrolyte as the gate insulator. Interestingly, all-printed FETs demonstrate an optimal electrical performance in terms of threshold voltages and device mobility and may very well be compared with devices fabricated using sputtered ITO electrodes. This observation originates from the selection of electrode/ channel materials from the same transparent semiconductor oxide family, resulting in the formation of In-Sn-Zn-O (ITZO) based diffused a-IGZO/ ITO interface that controls doping density while ensuring high electrical performance. Compressive spectroscopic studies reveal that Sn doping mediated excellent band alignment of IGZO with ITO electrodes is responsible for the excellent device performance observed. All-printed n-MOS based logic circuits have also been demonstrated towards new-generation portable electronics.

Towards a Mechanistic Understanding of Anaerobic Nitrate Dependent Iron Oxidation: Balancing Electron Uptake and Detoxification

Directory of Open Access Journals (Sweden)

Hans Karl Carlson

2012-02-01

Full Text Available The anaerobic oxidation of Fe(II by subsurface microorganisms is an important part of biogeochemical cycling in the environment, but the biochemical mechanisms used to couple iron oxidation to nitrate respiration are not well understood. Based on our own work and the evidence available in the literature, we propose a mechanistic model for anaerobic nitrate dependent iron oxidation. We suggest that anaerobic iron oxidizing microorganisms likely exist along a continuum including: 1 bacteria that inadvertently oxidize Fe(II by abiotic or biotic reactions with enzymes or chemical intermediates in their metabolic pathways (e.g. denitrification and suffer from toxicity or energetic penalty, 2 Fe(II tolerant bacteria that gain little or no growth benefit from iron oxidation but can manage the toxic reactions, and 3 bacteria that efficiently accept electrons from Fe(II to gain a growth advantage while preventing or mitigating the toxic reactions. Predictions of the proposed model are highlighted and experimental approaches are discussed.

The InP - SiO2 interface: Electron tunneling into oxide traps

International Nuclear Information System (INIS)

Prasad, S.J.; Owen, S.J.T.

1985-01-01

Indium Phosphide is an attractive material for high-speed devices. Though many successful devices have been built and demonstrated, InP MISFET's still suffer from drain current drift. From the data current drift measurements, the shift in the threshold voltage ΔV was computed for different times. It was found that a linear relationship exists between √ΔV and log(t). When a positive bias-stress was applied to the gate of an MIS capacitor for a time t, the C-V cure shifted by an amount ΔV and again, a linear relationship was observed between √ΔV and log(t). This was verified on four different gate insulators: pyrolytic SiO 2 at 320 0 C and 360 0 C, plasma oxide at 300 0 C and photo CVD oxide at 225 0 C. These results can only be explained by a model in which electrons tunnel from the substrate into oxide traps

Cu-Ag core–shell nanoparticles with enhanced oxidation stability for printed electronics

International Nuclear Information System (INIS)

Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Lee, Yung Jong; Lee, Hyuck Mo

2015-01-01

In this work, we synthesized uniform Cu–Ag core–shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core–shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu–Ag core–shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu–Ag core–shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu–Ag core–shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu–Ag core–shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties. (paper)

Large-Area Chemical Vapor Deposited MoS2 with Transparent Conducting Oxide Contacts toward Fully Transparent 2D Electronics

KAUST Repository

Dai, Zhenyu

2017-09-08

2D semiconductors are poised to revolutionize the future of electronics and photonics, much like transparent oxide conductors and semiconductors have revolutionized the display industry. Herein, these two types of materials are combined to realize fully transparent 2D electronic devices and circuits. Specifically, a large-area chemical vapor deposition process is developed to grow monolayer MoS2 continuous films, which are, for the first time, combined with transparent conducting oxide (TCO) contacts. Transparent conducting aluminum doped zinc oxide contacts are deposited by atomic layer deposition, with composition tuning to achieve optimal conductivity and band-offsets with MoS2. The optimized process gives fully transparent TCO/MoS2 2D electronics with average visible-range transmittance of 85%. The transistors show high mobility (4.2 cm2 V−1 s−1), fast switching speed (0.114 V dec−1), very low threshold voltage (0.69 V), and large switching ratio (4 × 108). To our knowledge, these are the lowest threshold voltage and subthreshold swing values reported for monolayer chemical vapor deposition MoS2 transistors. The transparent inverters show fast switching properties with a gain of 155 at a supply voltage of 10 V. The results demonstrate that transparent conducting oxides can be used as contact materials for 2D semiconductors, which opens new possibilities in 2D electronic and photonic applications.

Green Synthesis of Novel Polyaniline Nanofibers: Application in pH Sensing

Directory of Open Access Journals (Sweden)

Shivani Tanwar

2015-10-01

Full Text Available An optically active polyaniline nanomaterial (PANI-Nap, doped with (S-naproxen, was developed and evaluated as a potent pH sensor. We synthesized the material in one pot by the addition of the dopant, (S-naproxen, prior to polymerization, followed by the addition of the oxidizing agent (ammonium persulfate that causes polymerization of the aniline. This green chemistry approach allowed us to take only 1 h to produce a water-soluble and stable nanomaterial. UV-visible spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and X-ray photoelectron spectroscopy (XPS were used to characterize the designed nanomaterial. This nanomaterial exhibited excellent pH sensing properties and showed long term stability (up to one month without loss of sensor performance.

High Electron Mobility Thin-Film Transistors Based on Solution-Processed Semiconducting Metal Oxide Heterojunctions and Quasi-Superlattices

KAUST Repository

Lin, Yen-Hung; Faber, Hendrik; Labram, John G.; Stratakis, Emmanuel; Sygellou, Labrini; Kymakis, Emmanuel; Hastas, Nikolaos A.; Li, Ruipeng; Zhao, Kui; Amassian, Aram; Treat, Neil D.; McLachlan, Martyn; Anthopoulos, Thomas D.

2015-01-01

High mobility thin-film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin-film transistors is reported that exploits the enhanced electron transport properties of low-dimensional polycrystalline heterojunctions and quasi-superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band-like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature-dependent electron transport and capacitance-voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas-like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll-to-roll, etc.) and can be seen as an extremely promising technology for application in next-generation large area optoelectronics such as ultrahigh definition optical displays and large-area microelectronics where high performance is a key requirement.

High Electron Mobility Thin-Film Transistors Based on Solution-Processed Semiconducting Metal Oxide Heterojunctions and Quasi-Superlattices

KAUST Repository

Lin, Yen-Hung

2015-05-26

High mobility thin-film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin-film transistors is reported that exploits the enhanced electron transport properties of low-dimensional polycrystalline heterojunctions and quasi-superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band-like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature-dependent electron transport and capacitance-voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas-like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll-to-roll, etc.) and can be seen as an extremely promising technology for application in next-generation large area optoelectronics such as ultrahigh definition optical displays and large-area microelectronics where high performance is a key requirement.

Exploring the electron transfer pathway in the oxidation of avermectin by CYP107Z13 in Streptomyces ahygroscopicus ZB01.

Directory of Open Access Journals (Sweden)

Mei Li

Full Text Available Streptomyces ahygroscopicus ZB01 can effectively oxidize 4″-OH of avermectin to form 4″-oxo-avermectin. CYP107Z13 is responsible for this site-specific oxidation in ZB01. In the present study, we explored the electron transfer pathway in oxidation of avermectin by CYP107Z13 in ZB01. A putative [3Fe-4S] ferredoxin gene fd68 and two possible NADH-dependent ferredoxin reductase genes fdr18 and fdr28 were cloned from the genomic DNA of ZB01. fd68 gene disruption mutants showed no catalytic activity in oxidation of avermectin to form 4″-oxo-avermectin. To clarify whether FdR18 and FdR28 participate in the electron transfer during avermectin oxidation by CYP107Z13, two whole-cell biocatalytic systems were designed in E. coli BL21 (DE3, with one co-expressing CYP107Z13, Fd68 and FdR18 and the other co-expressing CYP107Z13, Fd68 and FdR28. Both of the two biocatalytic systems were found to be able to mediate the oxidation of avermectin to form 4″-oxo-avermectin. Thus, we propose an electron transfer pathway NADH→FdR18/FdR28→Fd68→CYP107Z13 for oxidation of avermectin to form 4″-oxo-avermectin in ZB01.

The molecular structure of 4-methylpyridine-N-oxide: Gas-phase electron diffraction and quantum chemical calculations

Science.gov (United States)

Belova, Natalya V.; Girichev, Georgiy V.; Kotova, Vitaliya E.; Korolkova, Kseniya A.; Trang, Nguyen Hoang

2018-03-01

The molecular structure of 4-methylpiridine-N-oxide, 4-MePyO, has been studied by gas-phase electron diffraction monitored by mass spectrometry (GED/MS) and quantum chemical (DFT) calculations. Both, quantum chemistry and GED analyses resulted in CS molecular symmetry with the planar pyridine ring. Obtained molecular parameters confirm the hyperconjugation in the pyridine ring and the sp2 hybridization concept of the nitrogen and carbon atoms in the ring. The experimental geometric parameters are in a good agreement with the parameters for non-substituted N-oxide and reproduced very closely by DFT calculations. The presence of the electron-donating CH3 substituent in 4-MePyO leads to a decrease of the ipso-angle and to an increase of r(N→O) in comparison with the non-substituted PyO. Electron density distribution analysis has been performed in terms of natural bond orbitals (NBO) scheme. The nature of the semipolar N→O bond is discussed.

Monitoring non-pseudomorphic epitaxial growth of spinel/perovskite oxide heterostructures by reflection high-energy electron diffraction

Energy Technology Data Exchange (ETDEWEB)

Schütz, P.; Pfaff, F.; Scheiderer, P.; Sing, M.; Claessen, R. [Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany)

2015-02-09

Pulsed laser deposition of spinel γ-Al{sub 2}O{sub 3} thin films on bulk perovskite SrTiO{sub 3} is monitored by high-pressure reflection high-energy electron diffraction (RHEED). The heteroepitaxial combination of two materials with different crystal structures is found to be inherently accompanied by a strong intensity modulation of bulk diffraction patterns from inelastically scattered electrons, which impedes the observation of RHEED intensity oscillations. Avoiding such electron surface-wave resonance enhancement by de-tuning the RHEED geometry allows for the separate observation of the surface-diffracted specular RHEED signal and thus the real-time monitoring of sub-unit cell two-dimensional layer-by-layer growth. Since these challenges are essentially rooted in the difference between film and substrate crystal structure, our findings are of relevance for the growth of any heterostructure combining oxides with different crystal symmetry and may thus facilitate the search for novel oxide heterointerfaces.

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

International Nuclear Information System (INIS)

Bee, Soo-Tueen; Sin, Lee Tin; Ratnam, C.T.; Haraveen, K.J.S.; Tee, Tiam-Ting; Rahmat, A.R.

2015-01-01

In this study, the effects of electron beam irradiation on the properties of copper(II) oxide when added to low-density polyethylene (LDPE) blends were investigated. It was found that the addition of low loading level of copper(II) oxide (⩽2 phr) to LDPE results in significantly poorer gel content and hot set results. However, the incorporation of higher loading level of copper(II) oxide (⩾3 phr) could slightly increase the degree of crosslinking in all irradiated LDPE composites. This is due to the fact that higher amounts of copper(II) oxide could slightly induce the formation of free radicals in LDPE matrix. Besides, increasing irradiation doses was also found to gradually increase the gel content of LDPE composites by generating higher amounts of free radicals. As a consequence, these higher amounts of free radicals released in the LDPE matrix could significantly increase the degree of crosslinking. The addition of copper(II) oxide could reduce the tensile strength and fracture strain (elongation at break) of LDPE composites because of poorer interfacial adhesion effect between copper(II) oxide particles and LDPE matrix. Meanwhile, increasing irradiation doses on all copper(II) oxide added LDPE composites could marginally increase the tensile strength. In addition, increasing irradiation dose could enhance the thermal stability of LDPE composites by increasing the decomposition temperature. The oxidation induction time (OIT) analysis showed that, because of the crosslinking network in the copper(II) oxide added LDPE composites, oxidation reaction is much delayed.

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

Energy Technology Data Exchange (ETDEWEB)

Bee, Soo-Tueen, E-mail: direct.beest@gmail.com [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Sin, Lee Tin, E-mail: direct.tinsin@gmail.com [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Ratnam, C.T. [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Haraveen, K.J.S.; Tee, Tiam-Ting [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Rahmat, A.R. [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

2015-10-01

In this study, the effects of electron beam irradiation on the properties of copper(II) oxide when added to low-density polyethylene (LDPE) blends were investigated. It was found that the addition of low loading level of copper(II) oxide (⩽2 phr) to LDPE results in significantly poorer gel content and hot set results. However, the incorporation of higher loading level of copper(II) oxide (⩾3 phr) could slightly increase the degree of crosslinking in all irradiated LDPE composites. This is due to the fact that higher amounts of copper(II) oxide could slightly induce the formation of free radicals in LDPE matrix. Besides, increasing irradiation doses was also found to gradually increase the gel content of LDPE composites by generating higher amounts of free radicals. As a consequence, these higher amounts of free radicals released in the LDPE matrix could significantly increase the degree of crosslinking. The addition of copper(II) oxide could reduce the tensile strength and fracture strain (elongation at break) of LDPE composites because of poorer interfacial adhesion effect between copper(II) oxide particles and LDPE matrix. Meanwhile, increasing irradiation doses on all copper(II) oxide added LDPE composites could marginally increase the tensile strength. In addition, increasing irradiation dose could enhance the thermal stability of LDPE composites by increasing the decomposition temperature. The oxidation induction time (OIT) analysis showed that, because of the crosslinking network in the copper(II) oxide added LDPE composites, oxidation reaction is much delayed.

Oxidative decomposition of aromatic hydrocarbons by electron beam irradiation

Science.gov (United States)

Han, Do-Hung; Stuchinskaya, Tatiana; Won, Yang-Soo; Park, Wan-Sik; Lim, Jae-Kyong

2003-05-01

Decomposition of aromatic volatile organic compounds (VOCs) under electron beam irradiation was studied in order to examine the kinetics of the process, to characterize the reaction product distribution and to develop a process of waste gas control technology. Toluene, ethylbenzene, o-, m-, p-xylenes and chlorobenzene were used as target materials. The experiments were carried out at doses ranging from 0.5 to 10 kGy, using a flow reactor utilized under electron beam irradiation. Maximum degrees of decomposition carried out at 10 kGy in air environment were 55-65% for “non-chlorinated” aromatic VOC and 85% for chlorobenzene. It was found that a combination of aromatic pollutants with chlorobenzene would considerably increase the degradation value up to nearly 50% compared to the same compounds in the absence of chlorine groups. Based on our experimental observation, the degradation mechanism of the aromatic compounds combined with chloro-compound suggests that a chlorine radical, formed from EB irradiation, induces a chain reaction, resulting in an accelerating oxidative destruction of aromatic VOCs.

Inductive crystal field control in layered metal oxides with correlated electrons

Energy Technology Data Exchange (ETDEWEB)

Balachandran, P. V.; Cammarata, A.; Rondinelli, J. M., E-mail: jrondinelli@nortwestern.edu [Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Nelson-Cheeseman, B. B. [School of Engineering, University of St. Thomas, St. Paul, Minnesota 55105 (United States); Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Bhattacharya, A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-07-01

We show that the NiO{sub 6} crystal field energies can be tailored indirectly via heterovalent A cation ordering in layered (La,A)NiO{sub 4} Ruddlesden–Popper (RP) oxides, where A = Sr, Ca, or Ba, using density functional calculations. We leverage as a driving force the electrostatic interactions between charged [LaO]{sup 1+} and neutral [AO]{sup 0} planes to inductively tune the Ni–O bond distortions, without intentional doping or epitaxial strain, altering the correlated d-orbital energies. We use this strategy to design cation ordered LaCaNiO{sub 4} and LaBaNiO{sub 4} with distortions favoring enhanced Ni e{sub g} orbital polarization, and find local electronic structure signatures analogous to those in RP La-cuprates, i.e., parent phases of the high-temperature superconducting oxides.

Visible-light-induced instability in amorphous metal-oxide based TFTs for transparent electronics

Directory of Open Access Journals (Sweden)

Tae-Jun Ha

2014-10-01

Full Text Available We investigate the origin of visible-light-induced instability in amorphous metal-oxide based thin film transistors (oxide-TFTs for transparent electronics by exploring the shift in threshold voltage (Vth. A large hysteresis window in amorphous indium-gallium-zinc-oxide (a-IGZO TFTs possessing large optical band-gap (≈3 eV was observed in a visible-light illuminated condition whereas no hysteresis window was shown in a dark measuring condition. We also report the instability caused by photo irradiation and prolonged gate bias stress in oxide-TFTs. Larger Vth shift was observed after photo-induced stress combined with a negative gate bias than the sum of that after only illumination stress and only negative gate bias stress. Such results can be explained by trapped charges at the interface of semiconductor/dielectric and/or in the gate dielectric which play a role in a screen effect on the electric field applied by gate voltage, for which we propose that the localized-states-assisted transitions by visible-light absorption can be responsible.

Visible-light-induced instability in amorphous metal-oxide based TFTs for transparent electronics

Energy Technology Data Exchange (ETDEWEB)

Ha, Tae-Jun [Department of Electronic Materials Engineering, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2014-10-15

We investigate the origin of visible-light-induced instability in amorphous metal-oxide based thin film transistors (oxide-TFTs) for transparent electronics by exploring the shift in threshold voltage (V{sub th}). A large hysteresis window in amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs possessing large optical band-gap (≈3 eV) was observed in a visible-light illuminated condition whereas no hysteresis window was shown in a dark measuring condition. We also report the instability caused by photo irradiation and prolonged gate bias stress in oxide-TFTs. Larger V{sub th} shift was observed after photo-induced stress combined with a negative gate bias than the sum of that after only illumination stress and only negative gate bias stress. Such results can be explained by trapped charges at the interface of semiconductor/dielectric and/or in the gate dielectric which play a role in a screen effect on the electric field applied by gate voltage, for which we propose that the localized-states-assisted transitions by visible-light absorption can be responsible.

Tuning the two-dimensional electron liquid at oxide interfaces by buffer-layer-engineered redox reactions

DEFF Research Database (Denmark)

Chen, Yunzhong; Green, Robert J.; Sutarto, Ronny

2017-01-01

Polar discontinuities and redox reactions provide alternative paths to create two-dimensional electron liquids (2DELs) at oxide interfaces. Herein, we report high mobility 2DELs at interfaces involving SrTiO3 (STO) achieved using polar La7/8Sr1/8MnO3 (LSMO) buffer layers to manipulate both...... polarities and redox reactions from disordered overlayers grown at room temperature. Using resonant x-ray reflectometry experiments, we quantify redox reactions from oxide overlayers on STO as well as polarity induced electronic reconstruction at epitaxial LSMO/STO interfaces. The analysis reveals how...... these effects can be combined in a STO/LSMO/disordered film trilayer system to yield high mobility modulation doped 2DELs, where the buffer layer undergoes a partial transformation from perovskite to brownmillerite structure. This uncovered interplay between polar discontinuities and redox reactions via buffer...

Electronic and atomic structure at metal-oxide heterointerfaces

International Nuclear Information System (INIS)

Schlueter, Christoph Friedrich

2013-01-01

The results of a series of investigations on modern oxide materials using hard X-ray photoelectron spectroscopy (HAXPES) combined with the X-ray standing wave (XSW) method are described in this thesis. The combination of hard X-ray photoelectron spectroscopy and X-ray standing waves enables the electronic structure to be measured with a spatial resolution in the picometer range. Under suitable preparation conditions, a quasi two-dimensional electron gas (2DEG) is formed at the heterointerfaces of strontium titanate (SrTiO 3 ) with polar oxides, such as lanthanum aluminate (LaAlO 3 ) or lanthanum gallate (LaGaO 3 ). Samples were grown at the ESRF and in Naples and surface X-ray diffraction confirmed the excellent epitaxial quality of the films. The XSW-method was used to reconstruct images of the structure of LaAlO 3 layers in real space. These images give evidence of distortions in the LaAlO 3 structure which facilitate the compensation of the potential differences. Furthermore, XSW/HAXPES measurements permit the Ti and Sr,O contributions to the 2DEG close to the Fermi level to be identified unambiguously. The analysis shows that the 3d band crosses the Fermi level and that some density of states is associated with oxygen vacancies. Superlattices of SrTiO 3 with polar calcium cuprate (CaCuO 2 ) were investigated by HAXPES. Similar to the case of SrTiO 3 /LaAlO 3 , the polarity of CaCuO 2 should lead to a diverging surface potential. The core level spectra from Ca, Sr, and Ti show that there is a redistribution mechanism for oxygen which compensates the potential differences. When the oxygen concentration is enhanced these superstructures become superconducting (T C = 40 K). The increased oxidation of the superconducting material is revealed by the additional components in the core level spectra of the metal atoms and in the appearance of a new screening channel in Cu 2p core level spectra, which signals the hole doping of the CaCuO 2 blocks. Magnetoresistive

Determination of vanadium in Syrian commercial and raffinate phosphoric acid

International Nuclear Information System (INIS)

Al-Merey, R.

2002-04-01

This study presents two methods for vanadium determination in Syrian commercial phosphoric acid. The vanadium (V) in the oxidized commercial phosphoric acid by ammonium persulfate solution is extracted from 5-M hydrochloride acid medium using N-benzoyl-N-phenyl hydroxyl amine (BPHA) in chloroform as an extracting solution. The first method, the extract vanadium as VOL 2 Cl is changed to V 2 O 3 L 4 complex by the addition of benzimidazole in 1-butanol to the violet organic layer. The absorbance is then measured at 440 nm (the molar absorptivity was found to be 3865 M -1 cm -1 ), where Beer law is applicable up to 36-μg ml -1 . the accuracy, precision and detection limit were found to be 3.7%, 77 ppb and 37 ppb, respectively. the second method, the organic layer is heated to evaporate chloroform, the residue is digested using 20% ammonium persulfate and 2-M sulfuric acid solutions. The vanadium concentration is measured spectrophotometrically by oxidizing gallic acid with persulfate (S 2 O 8 2- ) anion in phosphoric acid medium, where the vanadium (V) acts as a catalyst in the oxidation reaction. This method has a high sensitivity (∼10 -12 ) with accuracy and precision 5% and 0.621 ppb, respectively. Also Beer law at λ m ax=415 nm (ε=∼2 x 10 6 M -1 ) is applicable in the range 2.58-33.3 ppb. (author)

Lateral protonic/electronic hybrid oxide thin-film transistor gated by SiO2 nanogranular films

International Nuclear Information System (INIS)

Zhu, Li Qiang; Chao, Jin Yu; Xiao, Hui

2014-01-01

Ionic/electronic interaction offers an additional dimension in the recent advancements of condensed materials. Here, lateral gate control of conductivities of indium-zinc-oxide (IZO) films is reported. An electric-double-layer (EDL) transistor configuration was utilized with a phosphorous-doped SiO 2 nanogranular film to provide a strong lateral electric field. Due to the strong lateral protonic/electronic interfacial coupling effect, the IZO EDL transistor could operate at a low-voltage of 1 V. A resistor-loaded inverter is built, showing a high voltage gain of ∼8 at a low supply voltage of 1 V. The lateral ionic/electronic coupling effects are interesting for bioelectronics and portable electronics

Polycrystalline intrinsic zinc oxide to be used in transparent electronic devices

International Nuclear Information System (INIS)

Pimentel, A.; Fortunato, E.; Goncalves, A.; Marques, A.; Aguas, H.; Pereira, L.; Ferreira, I.; Martins, R.

2005-01-01

In this paper we present results of intrinsic/non-doped zinc oxide deposited at room temperature by radio frequency magnetron sputtering able to be used as a semiconductor material on electronic devices, like for example ozone gas sensors, ultra-violet detectors and thin film transistors. These films present a resistivity as high as 2.5x10 8 Ω cm with an optical transmittance of 90%. Concerning the structural properties, these films are polycrystalline presenting a uniform and very smooth surface

Electronic structure and dynamics of ordered clusters with ME or RE ions on oxide surface

Energy Technology Data Exchange (ETDEWEB)

Kulagin, N.A., E-mail: nkulagin@bestnet.kharkov.u [Kharkiv National University for Radio Electronics, Avenue Shakespeare 6-48, 61045 Kharkiv (Ukraine)

2011-03-15

Selected data of ab initio simulation of the electronic structure and spectral properties of either cluster with ions of iron, rare earth or actinium group elements have been presented here. Appearance of doped Cr{sup +4} ions in oxides, Cu{sup +2} in HTSC, Nd{sup +2} in solids has been discussed. Analysis of experimental data for plasma created ordered structures of crystallites with size of about 10{sup -9} m on surface of separate oxides are given, too. Change in the spectroscopic properties of clusters and nano-structures on surface of strontium titanate crystals discussed shortly using the X-ray line spectroscopy experimental results. - Research highlights: External influence and variation of technology induce changes in valence of nl ions in compounds. Wave function of cluster presented as anti-symmetrical set of ions wave functions. The main equation describes the self-consistent field depending on state of all electrons of cluster. Level scheme of Cr{sup 4+} ions in octo- and tetra-site corresponds to doped oxides spectra after treatment. Plasma treatment effects in appearance of systems of unit crystallites with size of about 10{sup -6}-10{sup -9} m.

Electronic structure and dynamics of ordered clusters with ME or RE ions on oxide surface

International Nuclear Information System (INIS)

Kulagin, N.A.

2011-01-01

Selected data of ab initio simulation of the electronic structure and spectral properties of either cluster with ions of iron, rare earth or actinium group elements have been presented here. Appearance of doped Cr +4 ions in oxides, Cu +2 in HTSC, Nd +2 in solids has been discussed. Analysis of experimental data for plasma created ordered structures of crystallites with size of about 10 -9 m on surface of separate oxides are given, too. Change in the spectroscopic properties of clusters and nano-structures on surface of strontium titanate crystals discussed shortly using the X-ray line spectroscopy experimental results. - Research highlights: → External influence and variation of technology induce changes in valence of nl ions in compounds. → Wave function of cluster presented as anti-symmetrical set of ions wave functions. → The main equation describes the self-consistent field depending on state of all electrons of cluster. → Level scheme of Cr 4+ ions in octo- and tetra-site corresponds to doped oxides spectra after treatment. → Plasma treatment effects in appearance of systems of unit crystallites with size of about 10 -6 -10 -9 m.

Application of AOPs for Removal of Stable Cyanide Compounds

Science.gov (United States)

Tsybikova, B.

2017-11-01

The main kinetic regularities of the photochemical oxidation of stable cyanide compounds (exemplified by hexacyanoferrates) by combined treatments involving direct photolysis and persulfate (oxidative system UV/S2O8 2-) and direct photolysis and hydrogen peroxide (oxidative system UV/H2O2) were studied. The possibility to perform oxidation processes within a wide pH range was shown. Based on to the energy efficiency, the rate of reaction and duration of the treatment, the considered oxidative systems can be arranged in the following order: {UV/S2O8 2-}>{UV/H2O2}>{UV}. The enhanced efficiency of hexacyanoferrates’ degradation by the combined system {UV/S2O8 2-} is due to the high oxidative capacity of sulfate anion radicals SO4 -· formed as a result of persulfate photolysis and its further disproportionation by Fe3+ and Fe2+ released through the decomposition of [Fe(CN)6]3-. Furthermore, the formation of ·OH radicals as a result of SO4 -· reacting with water also contributes to the enhanced oxidation efficiency. The combined method of {UV/S2O8 2-} treatment could be applied for the treatment of cyanide-containing wastewater and recycled water of different industries.

Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

KAUST Repository

Haslinger, Stefan

2014-11-03

This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

Making oxidation potentials predictable: Coordination of additives applied to the electronic fine tuning of an iron(II) complex

KAUST Repository

Haslinger, Stefan; Kü ck, Jens W.; Hahn, Eva M.; Cokoja, Mirza; Pö thig, Alexander; Basset, Jean-Marie; Kü hn, Fritz

2014-01-01

This work examines the impact of axially coordinating additives on the electronic structure of a bioinspired octahedral low-spin iron(II) N-heterocyclic carbene (Fe-NHC) complex. Bearing two labile trans-acetonitrile ligands, the Fe-NHC complex, which is also an excellent oxidation catalyst, is prone to axial ligand exchange. Phosphine- and pyridine-based additives are used for substitution of the acetonitrile ligands. On the basis of the resulting defined complexes, predictability of the oxidation potentials is demonstrated, based on a correlation between cyclic voltammetry experiments and density functional theory calculated molecular orbital energies. Fundamental insights into changes of the electronic properties upon axial ligand exchange and the impact on related attributes will finally lead to target-oriented manipulation of the electronic properties and consequently to the effective tuning of the reactivity of bioinspired systems.

Structural, electronic, mechanical, and dynamical properties of graphene oxides: A first principles study

International Nuclear Information System (INIS)

Dabhi, Shweta D.; Gupta, Sanjay D.; Jha, Prafulla K.

2014-01-01

We report the results of a theoretical study on the structural, electronic, mechanical, and vibrational properties of some graphene oxide models (GDO, a-GMO, z-GMO, ep-GMO and mix-GMO) at ambient pressure. The calculations are based on the ab-initio plane-wave pseudo potential density functional theory, within the generalized gradient approximations for the exchange and correlation functional. The calculated values of lattice parameters, bulk modulus, and its first order pressure derivative are in good agreement with other reports. A linear response approach to the density functional theory is used to derive the phonon frequencies. We discuss the contribution of the phonons in the dynamical stability of graphene oxides and detailed analysis of zone centre phonon modes in all the above mentioned models. Our study demonstrates a wide range of energy gap available in the considered models of graphene oxide and hence the possibility of their use in nanodevices.

Structural, electronic, mechanical, and dynamical properties of graphene oxides: A first principles study

Energy Technology Data Exchange (ETDEWEB)

Dabhi, Shweta D. [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364001 (India); Gupta, Sanjay D. [V. B. Institute of Science, Department of Physics, C. U. Shah University, Wadhwan City - 363030, Surendranagar (India); Jha, Prafulla K., E-mail: prafullaj@yahoo.com [Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002 (India)

2014-05-28

We report the results of a theoretical study on the structural, electronic, mechanical, and vibrational properties of some graphene oxide models (GDO, a-GMO, z-GMO, ep-GMO and mix-GMO) at ambient pressure. The calculations are based on the ab-initio plane-wave pseudo potential density functional theory, within the generalized gradient approximations for the exchange and correlation functional. The calculated values of lattice parameters, bulk modulus, and its first order pressure derivative are in good agreement with other reports. A linear response approach to the density functional theory is used to derive the phonon frequencies. We discuss the contribution of the phonons in the dynamical stability of graphene oxides and detailed analysis of zone centre phonon modes in all the above mentioned models. Our study demonstrates a wide range of energy gap available in the considered models of graphene oxide and hence the possibility of their use in nanodevices.

Structural and interfacial characteristics of thin (2 films grown by electron cyclotron resonance plasma oxidation on [100] Si substrates

International Nuclear Information System (INIS)

Nguyen, T.D.; Carl, D.A.; Hess, D.W.; Lieberman, M.A.; Gronsky, R.

1991-04-01

The feasibility of fabricating ultra-thin SiO 2 films on the order of a few nanometer thickness has been demonstrated. SiO 2 thin films of approximately 7 nm thickness have been produced by ion flux-controlled Electron Cyclotron Resonance plasma oxidation at low temperature on [100] Si substrates, in reproducible fashion. Electrical measurements of these films indicate that they have characteristics comparable to those of thermally grown oxides. The thickness of the films was determined by ellipsometry, and further confirmed by cross-sectional High-Resolution Transmission Electron Microscopy. Comparison between the ECR and the thermal oxide films shows that the ECR films are uniform and continuous over at least a few microns in lateral direction, similar to the thermal oxide films grown at comparable thickness. In addition, HRTEM images reveal a thin (1--1.5 nm) crystalline interfacial layer between the ECR film and the [100] substrate. Thinner oxide films of approximately 5 nm thickness have also been attempted, but so far have resulted in nonuniform coverage. Reproducibility at this thickness is difficult to achieve

Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

International Nuclear Information System (INIS)

Criquet, Justine; Leitner, Nathalie Karpel Vel

2015-01-01

The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent. - Highlights: • p-Hydroxybenzoic acid (HBA) is easily removed by e-beam irradiation. • The sulfate radicals formed from persulfate induce loss of the benzoic acid skeleton. • The dissolved oxygen concentration is a limiting parameter of the HBA degradation. • The effect of pH is minimized in presence of persulfate

Amorphous Tin Oxide as a Low-Temperature-Processed Electron-Transport Layer for Organic and Hybrid Perovskite Solar Cells

KAUST Repository

Barbe, Jeremy

2017-02-08

Chemical bath deposition (CBD) of tin oxide (SnO) thin films as an electron-transport layer (ETL) in a planar-heterojunction n-i-p organohalide lead perovskite and organic bulk-heterojunction (BHJ) solar cells is reported. The amorphous SnO (a-SnO) films are grown from a nontoxic aqueous bath of tin chloride at a very low temperature (55 °C) and do not require postannealing treatment to work very effectively as an ETL in a planar-heterojunction n-i-p organohalide lead perovskite or organic BHJ solar cells, in lieu of the commonly used ETL materials titanium oxide (TiO) and zinc oxide (ZnO), respectively. Ultraviolet photoelectron spectroscopy measurements on the glass/indium-tin oxide (ITO)/SnO/methylammonium lead iodide (MAPbI)/2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene device stack indicate that extraction of photogenerated electrons is facilitated by a perfect alignment of the conduction bands at the SnO/MAPbI interface, while the deep valence band of SnO ensures strong hole-blocking properties. Despite exhibiting very low electron mobility, the excellent interfacial energetics combined with high transparency (E > 4 eV) and uniform substrate coverage make the a-SnO ETL prepared by CBD an excellent candidate for the potentially low-cost and large-scale fabrication of organohalide lead perovskite and organic photovoltaics.

Improved cyclic oxidation resistance of electron beam physical vapor deposited nano-oxide dispersed {beta}-NiAl coatings for Hf-containing superalloy

Energy Technology Data Exchange (ETDEWEB)

Guo Hongbo [School of Materials Science and Engineering, Beihang University, No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, No. 37, Xueyuan Road, Beijing 100191 (China)], E-mail: Guo.hongbo@buaa.edu.cn; Cui Yongjing; Peng Hui; Gong Shengkai [School of Materials Science and Engineering, Beihang University, No. 37, Xueyuan Road, Beijing 100191 (China); Beijing Key Laboratory for Advanced Functional Materials and Thin Film Technology, Beihang University, No. 37, Xueyuan Road, Beijing 100191 (China)

2010-04-15

Oxide dispersed (OD) {beta}-NiAl coatings and OD-free {beta}-NiAl coatings were deposited onto a Hf-containing Ni-based superalloy by electron beam physical vapor deposition (EB-PVD). Excessive enrichment of Hf was found in the TGO on the OD-free coating due to outward diffusion of Hf from the superalloy, causing accelerated TGO thickening and spalling. The OD-coating effectively prevented Hf from outward diffusion. Only small amount of Hf diffused to the coating surface and improved the TGO adherence by virtue of the reactive element effect. The OD-coating exhibited an improved oxidation resistance as compared to the OD-free coating.

High Electron Mobility Thin‐Film Transistors Based on Solution‐Processed Semiconducting Metal Oxide Heterojunctions and Quasi‐Superlattices

Science.gov (United States)

Lin, Yen‐Hung; Faber, Hendrik; Labram, John G.; Stratakis, Emmanuel; Sygellou, Labrini; Kymakis, Emmanuel; Hastas, Nikolaos A.; Li, Ruipeng; Zhao, Kui; Amassian, Aram; Treat, Neil D.; McLachlan, Martyn

2015-01-01

High mobility thin‐film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin‐film transistors is reported that exploits the enhanced electron transport properties of low‐dimensional polycrystalline heterojunctions and quasi‐superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band‐like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature‐dependent electron transport and capacitance‐voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas‐like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll‐to‐roll, etc.) and can be seen as an extremely promising technology for application in next‐generation large area optoelectronics such as ultrahigh definition optical displays and large‐area microelectronics where high performance is a key requirement. PMID:27660741

Charge dynamics in aluminum oxide thin film studied by ultrafast scanning electron microscopy.

Science.gov (United States)

Zani, Maurizio; Sala, Vittorio; Irde, Gabriele; Pietralunga, Silvia Maria; Manzoni, Cristian; Cerullo, Giulio; Lanzani, Guglielmo; Tagliaferri, Alberto

2018-04-01

The excitation dynamics of defects in insulators plays a central role in a variety of fields from Electronics and Photonics to Quantum computing. We report here a time-resolved measurement of electron dynamics in 100 nm film of aluminum oxide on silicon by Ultrafast Scanning Electron Microscopy (USEM). In our pump-probe setup, an UV femtosecond laser excitation pulse and a delayed picosecond electron probe pulse are spatially overlapped on the sample, triggering Secondary Electrons (SE) emission to the detector. The zero of the pump-probe delay and the time resolution were determined by measuring the dynamics of laser-induced SE contrast on silicon. We observed fast dynamics with components ranging from tens of picoseconds to few nanoseconds, that fits within the timescales typical of the UV color center evolution. The surface sensitivity of SE detection gives to the USEM the potential of applying pump-probe investigations to charge dynamics at surfaces and interfaces of current nano-devices. The present work demonstrates this approach on large gap insulator surfaces. Copyright © 2018 Elsevier B.V. All rights reserved.

Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

Energy Technology Data Exchange (ETDEWEB)

Zhang Long [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang Tingmei [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu Peng [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)], E-mail: pliu@lzu.edu.cn

2008-12-30

Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

International Nuclear Information System (INIS)

Zhang Long; Wang Tingmei; Liu Peng

2008-01-01

Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

Achieving synergy between chemical oxidation and stabilization in a contaminated soil.

Science.gov (United States)

Srivastava, Vipul J; Hudson, Jeffrey Michael; Cassidy, Daniel P

2016-07-01

Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stable Organic Monolayers on Oxide-Free Silicon/Germanium in a Supercritical Medium: A New Route to Molecular Electronics.

Science.gov (United States)

Puniredd, Sreenivasa Reddy; Jayaraman, Sundaramurthy; Yeong, Sai Hooi; Troadec, Cedric; Srinivasan, M P

2013-05-02

Oxide-free Si and Ge surfaces have been passivated and modified with organic molecules by forming covalent bonds between the surfaces and reactive end groups of linear alkanes and aromatic species using single-step deposition in supercritical carbon dioxide (SCCO2). The process is suitable for large-scale manufacturing due to short processing times, simplicity, and high resistance to oxidation. It also allows the formation of monolayers with varying reactive terminal groups, thus enabling formation of nanostructures engineered at the molecular level. Ballistic electron emission microscopy (BEEM) spectra performed on the organic monolayer on oxide-free silicon capped by a thin gold layer reveals for the first time an increase in transmission of the ballistic current through the interface of up to three times compared to a control device, in contrast to similar studies reported in the literature suggestive of oxide-free passivation in SCCO2. The SCCO2 process combined with the preliminary BEEM results opens up new avenues for interface engineering, leading to molecular electronic devices.

The electronic structure of co-sputtered zinc indium tin oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Carreras, Paz; Antony, Aldrin; Bertomeu, Joan [Departament de Fisica Aplicada i Optica, Universitat de Barcelona, 08028 Barcelona (Spain); Gutmann, Sebastian [Department of Chemistry, University of South Florida, Tampa, Florida 33620 (United States); Schlaf, Rudy [Department of Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States)

2011-10-01

Zinc indium tin oxide (ZITO) transparent conductive oxide layers were deposited via radio frequency (RF) magnetron co-sputtering at room temperature. A series of samples with gradually varying zinc content was investigated. The samples were characterized with x-ray and ultraviolet photoemission spectroscopy (XPS, UPS) to determine the electronic structure of the surface. Valence and conduction bands maxima (VBM, CBM), and work function were determined. The experiments indicate that increasing Zn content results in films with a higher defect rate at the surface leading to the formation of a degenerately doped surface layer if the Zn content surpasses {approx}50%. Furthermore, the experiments demonstrate that ZITO is susceptible to ultraviolet light induced work function reduction, similar to what was earlier observed on ITO and TiO{sub 2} films.

Electron-induced desorption of europium atoms from oxidized tungsten surface: concentration dependence of low-energy peak

CERN Document Server

Davydov, S Y

2002-01-01

One discusses nature of electron induced desorption of Eu sup 0 europium atoms under E sub e irradiating electron low-energies (approx 30 eV) and peculiarities of yield dependence of Eu sup 0 atoms on their concentration at oxidized tungsten surface. Primary act of vacancy origination in europium adatom inner 5p-shell turned to be the determining stage. Evaluations have shown that just the first of two possible scenarios of ionization (electron intra-atomic to Eu adatom external quasi-level or realise of knocked out electron into vacuum) leads to Eu sup 0 desorption. One determined concentration threshold for yield of Eu sup 0 atoms

Oxidation of the FAD cofactor to the 8-formyl-derivative in human electron-transferring flavoprotein

Science.gov (United States)

Augustin, Peter; Toplak, Marina; Fuchs, Katharina; Gerstmann, Eva Christine; Prassl, Ruth; Winkler, Andreas; Macheroux, Peter

2018-01-01

The heterodimeric human (h) electron-transferring flavoprotein (ETF) transfers electrons from at least 13 different flavin dehydrogenases to the mitochondrial respiratory chain through a non-covalently bound FAD cofactor. Here, we describe the discovery of an irreversible and pH-dependent oxidation of the 8α-methyl group to 8-formyl-FAD (8f-FAD), which represents a unique chemical modification of a flavin cofactor in the human flavoproteome. Furthermore, a set of hETF variants revealed that several conserved amino acid residues in the FAD-binding pocket of electron-transferring flavoproteins are required for the conversion to the formyl group. Two of the variants generated in our study, namely αR249C and αT266M, cause glutaric aciduria type II, a severe inherited disease. Both of the variants showed impaired formation of 8f-FAD shedding new light on the potential molecular cause of disease development. Interestingly, the conversion of FAD to 8f-FAD yields a very stable flavin semiquinone that exhibited slightly lower rates of electron transfer in an artificial assay system than hETF containing FAD. In contrast, the formation of 8f-FAD enhanced the affinity to human dimethylglycine dehydrogenase 5-fold, indicating that formation of 8f-FAD modulates the interaction of hETF with client enzymes in the mitochondrial matrix. Thus, we hypothesize that the FAD cofactor bound to hETF is subject to oxidation in the alkaline (pH 8) environment of the mitochondrial matrix, which may modulate electron transport between client dehydrogenases and the respiratory chain. This discovery challenges the current concepts of electron transfer processes in mitochondria. PMID:29301933

Microstructural characterization of the cycling behavior of electrodeposited manganese oxide supercapacitors using 3D electron tomography

Science.gov (United States)

Dalili, N.; Clark, M. P.; Davari, E.; Ivey, D. G.

2016-10-01

Manganese oxide has been investigated extensively as an electrochemical capacitor or supercapacitor electrode material. Manganese oxide is inexpensive to fabricate and exhibits relatively high capacitance values, i.e., in excess of 200 F g-1 in many cases; the actual value depends very much on the fabrication method and test conditions. The cycling behavior of Mn oxide, fabricated using anodic electrodeposition, is investigated using slice and view techniques, via a dual scanning electron microscope (SEM) and focused ion beam (FIB) instrument to generate three-dimensional (3D) images, coupled with electrochemical characterization. The initial as-fabricated electrode has a rod-like appearance, with a fine-scale, sheet-like morphology within the rods. The rod-like structure remains after cycling, but there are significant morphological changes. These include partial dissolution of Mn oxide followed by redeposition of Mn oxide in regions close to the substrate. The redeposited material has a finer morphology than the original as-fabricated Mn oxide. The Mn oxide coverage is also better near the substrate. These effects result in an increase in the specific capacitance.

Silicon oxide: a non-innocent surface for molecular electronics and nanoelectronics studies.

Science.gov (United States)

Yao, Jun; Zhong, Lin; Natelson, Douglas; Tour, James M

2011-02-02

Silicon oxide (SiO(x)) has been widely used in many electronic systems as a supportive and insulating medium. Here, we demonstrate various electrical phenomena such as resistive switching and related nonlinear conduction, current hysteresis, and negative differential resistance intrinsic to a thin layer of SiO(x). These behaviors can largely mimic numerous electrical phenomena observed in molecules and other nanomaterials, suggesting that substantial caution should be paid when studying conduction in electronic systems with SiO(x) as a component. The actual electrical phenomena can be the result of conduction from SiO(x) at a post soft-breakdown state and not the presumed molecular or nanomaterial component. These electrical properties and the underlying mechanisms are discussed in detail.

Correlation between resistance-change effect in transition-metal oxides and secondary-electron contrast of scanning electron microscope images

International Nuclear Information System (INIS)

Kinoshita, K.; Kishida, S.; Yoda, T.

2011-01-01

Conductive atomic-force microscopy (C-AFM) writing is attracting attention as a technique for clarifying the switching mechanism of resistive random-access memory by providing a wide area filled with filaments, which can be regarded as one filament with large radius. The writing area on a nickel-oxide (NiO) film formed by conductive atomic-force microscopy was observed by scanning electron microscope, and a correlation between the contrast in a secondary-electron image (SEI) and the resistance written by C-AFM was revealed. In addition, the dependence of the SEI contrast on the beam accelerating voltage (V accel ) suggests that the resistance-change effect occurs near the surface of the NiO film. As for the effects of electron irradiation and vacuum annealing on the C-AFM writing area, it was shown that the resistance-change effect is caused by exchange of oxygen with the atmosphere at the surface of the NiO film. This result suggests that the low-resistance and high-resistance areas are, respectively, p-type Ni 1+δ O (δ 1+δ O (δ≥ 0).

Number of outer electrons as descriptor for adsorption processes on transition metals and their oxides

DEFF Research Database (Denmark)

Calle-Vallejo, Federico; Inoglu, Nilay G.; Su, Hai-Yan

2013-01-01

The trends in adsorption energies of the intermediates of the oxygen reduction and evolution reactions on transition metals and their oxides are smoothly captured by the number of outer electrons. This unique descriptor permits the construction of predictive adsorption-energy grids and explains t...

Transmission electron microscopy of oxide dispersion strengthened (ODS) molybdenum: effects of irradiation on material microstructure

International Nuclear Information System (INIS)

Baranwal, R.; Burke, M.G.

2003-01-01

Oxide dispersion strengthened (ODS) molybdenum has been characterized using transmission electron microscopy (TEM) to determine the effects of irradiation on material microstructure. This work describes the results-to-date from TEM characterization of unirradiated and irradiated ODS molybdenum. The general microstructure of the unirradiated material consists of fine molybdenum grains (< 5 (micro)m average grain size) with numerous low angle boundaries and isolated dislocation networks. 'Ribbon'-like lanthanum oxides are aligned along the working direction of the product form and are frequently associated with grain boundaries, serving to inhibit grain boundary and dislocation movement. In addition to the 'ribbons', discrete lanthanum oxide particles have also been detected. After irradiation, the material is characterized by the presence of nonuniformly distributed large (∼ 20 to 100 nm in diameter), multi-faceted voids, while the molybdenum grain size and oxide morphology appear to be unaffected by irradiation

Chemical decontamination method

Energy Technology Data Exchange (ETDEWEB)

Inoue, Susumu; Ikehara, Fumiaki; Miyazaki, Atsuo

1994-04-12

Pipelines and equipments deposited with cruds undergo an oxidative dissolving treatment by a cleaning liquid using persulfuric acid and persulfate. Then a reducing agent is added to cleaning liquid wastes by an excess amount than required for decomposing and reducing the remaining persulfuric acid and persulfate. As the reducing agent, one or more of materials selected from ascorbic acid, erythorbic acid, oxalic acid, salts and derivatives thereof are used. Further, if required, sulfuric acid or sulfuric acid is also added. This can effectively dissolve even less soluble cruds to shorten the processing time, thereby reducing the operators' exposure dose and attaining devoluming of the wastes. (T.M.).

Chemical decontamination method

International Nuclear Information System (INIS)

Inoue, Susumu; Ikehara, Fumiaki; Miyazaki, Atsuo.

1994-01-01

Pipelines and equipments deposited with cruds undergo an oxidative dissolving treatment by a cleaning liquid using persulfuric acid and persulfate. Then a reducing agent is added to cleaning liquid wastes by an excess amount than required for decomposing and reducing the remaining persulfuric acid and persulfate. As the reducing agent, one or more of materials selected from ascorbic acid, erythorbic acid, oxalic acid, salts and derivatives thereof are used. Further, if required, sulfuric acid or sulfuric acid is also added. This can effectively dissolve even less soluble cruds to shorten the processing time, thereby reducing the operators' exposure dose and attaining devoluming of the wastes. (T.M.)

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

Science.gov (United States)

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

Rapid synthesis of an electron-deficient t-BuPHOX ligand: cross-coupling of aryl bromides with secondary phosphine oxides

KAUST Repository

McDougal, Nolan T.

2010-10-01

Herein an efficient and direct copper-catalyzed coupling of oxazoline-containing aryl bromides with electron-deficient secondary phosphine oxides is reported. The resulting tertiary phosphine oxides can be reduced to prepare a range of PHOX ligands. The presented strategy is a useful alternative to known methods for constructing PHOX derivatives.

Rapid synthesis of an electron-deficient t-BuPHOX ligand: cross-coupling of aryl bromides with secondary phosphine oxides

KAUST Repository

McDougal, Nolan T.; Streuff, Jan; Mukherjee, Herschel; Virgil, Scott C.; Stoltz, Brian M.

2010-01-01

Herein an efficient and direct copper-catalyzed coupling of oxazoline-containing aryl bromides with electron-deficient secondary phosphine oxides is reported. The resulting tertiary phosphine oxides can be reduced to prepare a range of PHOX ligands. The presented strategy is a useful alternative to known methods for constructing PHOX derivatives.

Electron impact ionisation cross sections of iron oxides

Science.gov (United States)

Huber, Stefan E.; Mauracher, Andreas; Sukuba, Ivan; Urban, Jan; Maihom, Thana; Probst, Michael

2017-12-01

We report electron impact ionisation cross sections (EICSs) of iron oxide molecules, FexOx and FexOx+1 with x = 1, 2, 3, from the ionisation threshold to 10 keV, obtained with the Deutsch-Märk (DM) and binary-encounter-Bethe (BEB) methods. The maxima of the EICSs range from 3.10 to 9 . 96 × 10-16 cm2 located at 59-72 eV and 5.06 to 14.32 × 10-16 cm2 located at 85-108 eV for the DM and BEB approaches, respectively. The orbital and kinetic energies required for the BEB method are obtained by employing effective core potentials for the inner core electrons in the quantum chemical calculations. The BEB cross sections are 1.4-1.7 times larger than the DM cross sections which can be related to the decreasing population of the Fe 4s orbitals upon addition of oxygen atoms, together with the different methodological foundations of the two methods. Both the DM and BEB cross sections can be fitted excellently to a simple analytical expression used in modelling and simulation codes employed in the framework of nuclear fusion research. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80308-2.

Electronic structure, charge transfer, and intrinsic luminescence of gadolinium oxide nanoparticles: Experiment and theory

Science.gov (United States)

Zatsepin, D. A.; Boukhvalov, D. W.; Zatsepin, A. F.; Kuznetsova, Yu. A.; Mashkovtsev, M. A.; Rychkov, V. N.; Shur, V. Ya.; Esin, A. A.; Kurmaev, E. Z.

2018-04-01

The cubic (c) and monoclinic (m) polymorphs of Gd2O3 were studied using the combined analysis of several materials science techniques - X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. Density functional theory (DFT) based calculations for the samples under study were performed as well. The cubic phase of gadolinium oxide (c-Gd2O3) synthesized using a precipitation method exhibits spheroidal-like nanoclusters with well-defined edges assembled from primary nanoparticles with an average size of 50 nm, whereas the monoclinic phase of gadolinium oxide (m-Gd2O3) deposited using explosive pyrolysis has a denser structure compared with natural gadolinia. This phase also has a structure composed of three-dimensional complex agglomerates without clear-edged boundaries that are ∼21 nm in size plus a cubic phase admixture of only 2 at.% composed of primary edge-boundary nanoparticles ∼15 nm in size. These atomic features appear in the electronic structure as different defects ([Gd…Osbnd OH] and [Gd…Osbnd O]) and have dissimilar contributions to the charge-transfer processes among the appropriate electronic states with ambiguous contributions in the Gd 5р - O 2s core-like levels in the valence band structures. The origin of [Gd…Osbnd OH] defects found by XPS was well-supported by PL analysis. The electronic and atomic structures of the synthesized gadolinias calculated using DFT were compared and discussed on the basis of the well-known joint OKT-van der Laan model, and good agreement was established.

Electronic and atomic structure at metal-oxide heterointerfaces

Energy Technology Data Exchange (ETDEWEB)

Schlueter, Christoph Friedrich

2013-07-01

The results of a series of investigations on modern oxide materials using hard X-ray photoelectron spectroscopy (HAXPES) combined with the X-ray standing wave (XSW) method are described in this thesis. The combination of hard X-ray photoelectron spectroscopy and X-ray standing waves enables the electronic structure to be measured with a spatial resolution in the picometer range. Under suitable preparation conditions, a quasi two-dimensional electron gas (2DEG) is formed at the heterointerfaces of strontium titanate (SrTiO{sub 3}) with polar oxides, such as lanthanum aluminate (LaAlO{sub 3}) or lanthanum gallate (LaGaO{sub 3}). Samples were grown at the ESRF and in Naples and surface X-ray diffraction confirmed the excellent epitaxial quality of the films. The XSW-method was used to reconstruct images of the structure of LaAlO{sub 3} layers in real space. These images give evidence of distortions in the LaAlO{sub 3} structure which facilitate the compensation of the potential differences. Furthermore, XSW/HAXPES measurements permit the Ti and Sr,O contributions to the 2DEG close to the Fermi level to be identified unambiguously. The analysis shows that the 3d band crosses the Fermi level and that some density of states is associated with oxygen vacancies. Superlattices of SrTiO{sub 3} with polar calcium cuprate (CaCuO{sub 2}) were investigated by HAXPES. Similar to the case of SrTiO{sub 3}/LaAlO{sub 3}, the polarity of CaCuO{sub 2} should lead to a diverging surface potential. The core level spectra from Ca, Sr, and Ti show that there is a redistribution mechanism for oxygen which compensates the potential differences. When the oxygen concentration is enhanced these superstructures become superconducting (T{sub C} = 40 K). The increased oxidation of the superconducting material is revealed by the additional components in the core level spectra of the metal atoms and in the appearance of a new screening channel in Cu 2p core level spectra, which signals the hole

Lateral protonic/electronic hybrid oxide thin-film transistor gated by SiO{sub 2} nanogranular films

Energy Technology Data Exchange (ETDEWEB)

Zhu, Li Qiang, E-mail: lqzhu@nimte.ac.cn; Chao, Jin Yu; Xiao, Hui [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2014-12-15

Ionic/electronic interaction offers an additional dimension in the recent advancements of condensed materials. Here, lateral gate control of conductivities of indium-zinc-oxide (IZO) films is reported. An electric-double-layer (EDL) transistor configuration was utilized with a phosphorous-doped SiO{sub 2} nanogranular film to provide a strong lateral electric field. Due to the strong lateral protonic/electronic interfacial coupling effect, the IZO EDL transistor could operate at a low-voltage of 1 V. A resistor-loaded inverter is built, showing a high voltage gain of ∼8 at a low supply voltage of 1 V. The lateral ionic/electronic coupling effects are interesting for bioelectronics and portable electronics.

Prediction of Petroleum Hydrocarbon Bioavailability in Contaminated Soils and Sediments