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1

Oxidation of chlorinated ethenes by heat-activated persulfate: kinetics and products.  

PubMed

In situ chemical oxidation (ISCO) and in situ thermal remediation (ISTR) are applicable to treatment of groundwater contaminated with chlorinated ethenes. ISCO with persulfate (S2O8(2-)) requires activation, and this can be achieved with the heat from ISTR, so there may be advantages to combining these technologies. To explore this possibility, we determined the kinetics and products of chlorinated ethene oxidation with heat-activated persulfate and compared them to the temperature dependence of other degradation pathways. The kinetics of chlorinated ethene disappearance were pseudo-first-order for 1-2 half-lives, and the resulting rate constants-measured from 30 to 70 degrees C--fit the Arrhenius equation, yielding apparent activation energies of 101 +/- 4 kJ mol(-1) for tetrachloroethene (PCE), 108 +/- 3 kJ mol(-1) for trichloroethene (TCE), 144 +/- 5 kJ mol(-1) for cis-1,2-dichloroethene (cis-DCE), and 141 +/- 2 kJ mol(-1) for trans-1,2-dichloroethene (trans-DCE). Chlorinated byproducts were observed, but most of the parent material was completely dechlorinated. Arrhenius parameters for hydrolysis and oxidation by persulfate or permanganate were used to calculate rates of chlorinated ethene degradation by these processes over the range of temperatures relevant to ISTR and the range of oxidant concentrations and pH relevant to ISCO. PMID:17328217

Waldemer, Rachel H; Tratnyek, Paul G; Johnson, Richard L; Nurmi, James T

2007-02-01

2

Impact of activation methods on persulfate oxidation of methyl tert-butyl ether.  

PubMed

To provide guidance on the selection of proper persulfate processes for the remediation of MTBE contaminated groundwater, MTBE aqueous solutions were treated with three common field persulfate processes including heat activated persulfate, Fe(III)-EDTA activated persulfate and alkaline persulfate, respectively. The results were compared with MTBE oxidation by Fenton's reagent and persulfate alone at 25°C. The impact of the activating conditions on the fate of MTBE and its daughter products was investigated. Heat activation at 40°C offered the most rapid removal of MTBE and its daughter products, while Fe(III)-EDTA activation showed higher efficiency of MTBE removal but low removal efficiency of its daughter products. On the other hand, alkaline persulfate showed slower kinetics for the removal of MTBE and less accumulation of the daughter products. Furthermore, tert-butyl alcohol and acetone were observed as the main purgeable daughter products along with a small amount of tert-butyl formate in persulfate oxidation of MTBE, while tert-butyl formate, tert-butyl alcohol and acetone were the main products in Fenton oxidation. Mechanistic analysis suggests that degradation of MTBE by persulfate most likely happens via non-oxygen demand pathways, different from the dominant oxygen demand degradation pathways observed in Fenton oxidation. PMID:24246442

Deng, Dayi; Peng, Libin; Guan, Mengyun; Kang, Yuan

2014-01-15

3

Ultrasonically enhanced persulfate oxidation of polyethylene surfaces  

Microsoft Academic Search

The ultrasonically enhanced oxidation of polyethylene surfaces by potassium and ammonium persulfates is described. The use of ultrasound allows significant levels of surface modification to be achieved using these oxidizing agents under mild conditions. Changes in the water contact angle and attenuated total reflection infra-red spectra were used to follow the changes in surface chemistry. Variation of conditions such as

Fiona Keen

1996-01-01

4

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

Microsoft Academic Search

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to

Chiel Cuypers; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

2000-01-01

5

Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments  

SciTech Connect

Persulfate oxidation was validated as a method to predict polycyclic aromatic hydrocarbon (PAH) bioavailability in soils and sediments. It was demonstrated for 14 field contaminated soils and sediments that residual PAH concentrations after a short (3 h) persulfate oxidation correspond well to residual PAH concentrations after 21 days of biodegradation. Persulfate oxidation of samples that had first been subjected to biodegradation yielded only limited additional PAH oxidation. This implies that oxidation and biodegradation removed approximately the same PAH fraction. Persulfate oxidation thus provides a good and rapid method for the prediction of PAH bioavailability. Thermogravimetric analysis of oxidized and untreated samples showed that persulfate oxidation primarily affected expanded organic matter. The results indicate that this expanded organic matter contained mainly readily bioavailable PAHs.

Cuypers, C.; Grotenhuis, T.; Joziasse, J.; Rulkens, W.

2000-05-15

6

Liquid-phase catalytic oxidation of CO by ammonium persulfate  

SciTech Connect

The catalytic oxidation of carbon monoxide in aqueous solutions is investigated. The abilities of ammonium persulfate, palladium hydroxide, and silver oxide to force the oxidation are discussed. The rates for these reactions are displayed graphically. The reaction rates as a function of the concentrations of the above-mentioned reactants are determined. An excess of persulfate is found to oxidize Pd(II) to Pd(IV), and this produces a reduction in the rate of CO oxidation. The oxidation of CO is preceeded in the reaction by the interaction of the persulfate with the metal catalyst.

Golodov, V.A.; Abilov, M.T.; Sokol'skii, D.V.

1984-01-01

7

Degradation of volatile organic compounds with thermally activated persulfate oxidation.  

PubMed

This study investigated the extent and treatability of the degradation of 59 volatile organic compounds (VOCs) listed in the EPA SW-846 Method 8260B with thermally activated persulfate oxidation. Data on the degradation of the 59 VOCs (in mixture) reacted with sodium persulfate in concentrations of 1 g l(-1) and 5 g l(-1) and at temperatures of 20 degrees C, 30 degrees C, and 40 degrees C were obtained. The results indicate that persulfate oxidation mechanisms are effective in degrading many VOCs including chlorinated ethenes (CEs), BTEXs and trichloroethanes that are frequently detected in the subsurface at contaminated sites. Most of the targeted VOCs were rapidly degraded under the experimental conditions while some showed persistence to the persulfate oxidation. Compounds with "CC" bonds or with benzene rings bonded to reactive functional groups were readily degraded. Saturated hydrocarbons and halogenated alkanes were much more stable and difficult to degrade. For those highly persulfate-degradable VOCs, degradation was well fitted with a pseudo first-order decay model. Activation energies of reactions of CEs and BTEXs with persulfate were determined. The degradation rates increased with increasing reaction temperature and oxidant concentration. Nevertheless, to achieve complete degradation of persulfate-degradable compounds, the systems required sufficient amounts of persulfate to sustain the degradation reaction. PMID:16202809

Huang, Kun-Chang; Zhao, Zhiqiang; Hoag, George E; Dahmani, Amine; Block, Philip A

2005-10-01

8

Degradation of volatile organic compounds with thermally activated persulfate oxidation  

Microsoft Academic Search

This study investigated the extent and treatability of the degradation of 59 volatile organic compounds (VOCs) listed in the EPA SW-846 Method 8260B with thermally activated persulfate oxidation. Data on the degradation of the 59 VOCs (in mixture) reacted with sodium persulfate in concentrations of 1gl?1 and 5gl?1 and at temperatures of 20°C, 30°C, and 40°C were obtained. The results

Kun-Chang Huang; Zhiqiang Zhao; George E. Hoag; Amine Dahmani; Philip A. Block

2005-01-01

9

Release of chromium from soils with persulfate chemical oxidation.  

PubMed

An important part of the evaluation of the effectiveness of persulfate in situ chemical oxidation (ISCO) for treating organic contaminants is to identify and understand its potential impact on metal co-contaminants in the subsurface. Chromium is a redox-sensitive and toxic metal the release of which poses considerable risk to human health. The objective of this study was to investigate the impact of persulfate chemical oxidation on the release of chromium from three soils varying in physical-chemical properties. Soils were treated with unactivated and activated persulfate [activated with Fe(II), Fe(II)-EDTA, and alkaline pH] at two different concentrations (i.e., 41 mM and 2.1 mM persulfate) for 48 h and 6 months and were analyzed for release of chromium. Results show that release of chromium with persulfate chemical oxidation depends on the soil type and the activation method. Sandy soil with low oxidant demand released more chromium compared to soils with high oxidant demand. More chromium was released with alkaline pH activation. Alkaline pH and high Eh conditions favor oxidation of Cr(III) to Cr(VI), which is the main mechanism of release of chromium with persulfate chemical oxidation. Unactivated and Fe(II)-activated persulfate decreased pH and at low pH in absence of EDTA chromium release is not a concern. These results indicate that chromium release can be anticipated based on the given site and treatment conditions, and ISCO system can be designed to minimize potential chromium release when treating soils and groundwater contaminated with both organic and metal contaminants. PMID:24028318

Kaur, Kawalpreet; Crimi, Michelle

2014-01-01

10

Microwave-enhanced persulfate oxidation to treat mature landfill leachate.  

PubMed

Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. Kinetics of persulfate oxidation in MOP, effects of pH and persulfate doses on fates of derivative organic acids, and the energy cost of MOP were evaluated. The results showed that total organic carbon (TOC) removal of 79.4%, color removal of 88.4%, and UV254 removal of 77.1% were reached at MOP 550 W/85 °C within 30 min. The kinetics of oxidation by MOP followed the first-order reaction. For a given persulfate dose, the reaction rate increased with the microwave power setting (775 W>550 W>325 W>128 W) with reaction rate constants ranging from 10(-5) to 10(-2) min(-1). The adverse effects on reaction rates under higher microwave power settings and high persulfate doses are plausibly caused by excessive persulfate oxidation and self-scavenging termination of free radicals. During the MOP treatment, TOC/COD ratio dropped with time and an 86.7% reduction in TOC/COD ratio after 120 min at pH 7. Oxalic acid was the major derivative and its concentrations were higher under acidic conditions. Malic, lactic, and acetic acids were formed and soon degraded, and the solution pH has an insignificant effect on their fates. The energy cost of MOP (USD$6.03/m(3)) is essentially similar to that of conventional heating oxidation (CHO) (USD$6.10/m(3)). PMID:25463221

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

2015-03-01

11

Effect of sorption on contaminant oxidation in activated persulfate systems.  

PubMed

Sorption of hydrophobic contaminants to soils and subsurface solids is a significant limitation for the in situ chemical oxidation (ISCO) remediation of contaminated sites. A recently developed ISCO reagent, activated persulfate, was investigated for its potential to provide enhanced treatment of sorbed contaminants, a phenomenon that has previously been observed in catalyzed H(2)O(2) propagations (CHP; modified Fenton's reagent). Perchloroethylene (PCE) and hexachlorocyclopentadiene (HCCP) were sorbed to diatomaceous earth and treated with CHP, iron (II)-citrate-activated persulfate, and base-activated persulfate. Gas-purge desorption was used to measure the maximum natural rate of desorption of the compounds. Enhanced treatment of both sorbed probe compounds was observed in CHP reactions, with PCE and HCCP destruction occurring more rapidly than their respective rates of gas-purge desorption. However, probe compound loss in both formulations of activated persulfate was equal or less than the rates of gas-purge desorption, indicating that enhanced treatment of the sorbed contaminants did not occur in the persulfate reactions. Activated persulfate treatment is likely ineffective for hydrophobic compounds that are sorbed to soils and subsurface solids, and is probably more effective for compounds that are not limited by desorption. PMID:19847699

Teel, Amy L; Cutler, Lynn M; Watts, Richard J

2009-09-01

12

Degradation of 1,4-dioxane in water with heat- and Fe(2+)-activated persulfate oxidation.  

PubMed

This research investigated the 1,4-dioxane (1,4-D) degradation efficiency and rate during persulfate oxidation at different temperatures, with and without Fe(2+) addition, also considering the effect of pH and persulfate concentration on the oxidation of 1,4-D. Degradation pathways for 1,4-D have also been proposed based on the decomposition intermediates and by-products. The results indicate that 1,4-D was completely degraded with heat-activated persulfate oxidation within 3-80 h. The kinetics of the 1,4-D degradation process fitted well to a pseudo-first-order reaction model. Temperature was identified as the most important factor influencing the 1,4-D degradation rate during the oxidation process. As the temperature increased from 40 to 60 °C, the degradation rate improved significantly. At 40 °C, the addition of Fe(2+) also increased the 1,4-D degradation rate. Interestingly, at 50 and 60 °C, the 1,4-D degradation rate decreased slightly with the addition of Fe(2+). This reduced degradation rate may be attributed to the rapid conversion of Fe(2+) to Fe(3+) and the production of an Fe(OH)3 precipitate which limited the ultimate oxidizing capability of persulfate with Fe(2+) under higher temperatures. Higher persulfate concentrations led to higher 1,4-D degradation rates, but pH adjustment had no significant effect on the 1,4-D degradation rate. The identification of intermediates and by-products in the aqueous and gas phases showed that acetaldehyde, acetic acid, glycolaldehyde, glycolic acid, carbon dioxide, and hydrogen ion were generated during the persulfate oxidation process. A carbon balance analysis showed that 96 and 93% of the carbon from the 1,4-D degradation were recovered as by-products with and without Fe(2+) addition, respectively. Overall, persulfate oxidation of 1,4-D is promising as an economical and highly efficient technology for treatment of 1,4-D-contaminated water. PMID:24590601

Zhao, Long; Hou, Hong; Fujii, Ayuko; Hosomi, Masaaki; Li, Fasheng

2014-06-01

13

Evaluation of persulfate oxidative wet scrubber for removing BTEX gases.  

PubMed

Soil vapor extraction (SVE) coupled with air sparging of groundwater is a method commonly used to remediate soil and groundwater contaminated with volatile organic petroleum contaminants such as gasoline. These hazardous contaminants are mainly attributable to the compounds-benzene, toluene, ethylbenzene, and xylenes (known collectively as BTEX). Exhaust gas from SVE may contain BTEX, and therefore must be treated before being discharged. This study evaluated the use of iron-activated persulfate chemical oxidation in conjunction with a wet scrubbing system, i.e., a persulfate oxidative scrubber (POS) system, to destroy BTEX gases. The persulfate anions can be activated by citric acid (CA) chelated Fe(2+) to generate sulfate radicals (SO(4)(*-), E degrees =2.4V), which may rapidly degrade BTEX in the aqueous phase and result in continuous destruction of the BTEX gases. The results show that persulfate activation occurred as a result of continuous addition of the citric acid chelated Fe(2+) activator, which readily oxidized the dissolved BTEX. Based on initial results from the aqueous phase, a suitable Fe(2+)/CA molar ratio of 5/3 was determined and used to initiate activation in the subsequent POS system tests. In the POS system, using persulfate as a scrubber solution and with activation by injecting Fe(2+)/CA activators under two testing conditions, varying iron concentrations and pumping rates, resulted in an approximate 50% removal of BTEX gases. During the course of the tests which in corporate activation, a complete destruction of BTEX was achieved in the aqueous phase. It is noted that no removal of BTEX occurred in the control tests which did not include activation. The results of this study would serve as a reference for future studies into the practical chemical oxidation of waste gas streams. PMID:18829165

Liang, Chenju; Chen, Yan-Jyun; Chang, Keng-Jung

2009-05-30

14

Effect of persulfate on the oxidation of benzotriazole and humic acid by e-beam irradiation  

Microsoft Academic Search

These days, the use of persulfate in advanced oxidation processes (AOPs) has gained more attention as an emerging clean and efficient technology to degrade the organic pollutants. The objective of this study was to investigate the effect of the addition of persulfate on the oxidation of benzotriazole (BT) and humic acids (HAs) by irradiation. The degradation of BT (3.7?M) was

Babak Roshani; Nathalie Karpel Vel Leitner

2011-01-01

15

Identification of persulfate oxidation products of polycyclic aromatic hydrocarbon during remediation of contaminated soil.  

PubMed

The extent of PAH transformation, the formation and transformation of reaction byproducts during persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) in coking plant soil was investigated. Pre-oxidation analyses indicated that oxygen-containing PAHs (oxy-PAHs) existed in the soil. Oxy-PAHs including 1H-phenalen-1-one, 9H-fluoren-9-one, and 1,8-naphthalic anhydride were also produced during persulfate oxidation of PAHs. Concentration of 1,8-naphthalic anhydride at 4h in thermally activated (50°C) persulfate oxidation (TAPO) treatment increased 12.7 times relative to the oxidant-free control. Additionally, the oxy-PAHs originally present and those generated during oxidation can be oxidized by unactivated or thermally activated persulfate oxidation. For example, 9H-fluoren-9-one concentration decreased 99% at 4h in TAPO treatment relative to the control. Thermally activated persulfate resulted in greater oxy-PAHs removal than unactivated persulfate. Overall, both unactivated and thermally activated persulfate oxidation of PAH-contaminated soil reduced PAH mass, and oxidized most of the reaction byproducts. Consequently, this treatment process could limit environmental risk related to the parent compound and associated reaction byproducts. PMID:24862467

Liao, Xiaoyong; Zhao, Dan; Yan, Xiulan; Huling, Scott G

2014-07-15

16

UV-activated persulfate oxidation and regeneration of NOM-Saturated granular activated carbon.  

PubMed

A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 10(4) mJ/cm(2). The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC. PMID:25697692

An, Dong; Westerhoff, Paul; Zheng, Mengxin; Wu, Mengyuan; Yang, Yu; Chiu, Chao-An

2015-04-15

17

Persulfate oxidation of trichloroethylene with and without iron activation in porous media  

Microsoft Academic Search

In situ chemical oxidation with persulfate anion (S2O82-) is a viable technique for remediation of groundwater contaminants such as trichloroethylene (TCE). An accelerated reaction using S2O82- to destroy TCE can be achieved via chemical activation with ferrous ion to generate sulfate radicals (SO4-·)(E°=2.6V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a

Chenju Liang; I-Ling Lee; I-Yuang Hsu; Ching-Ping Liang; Yu-Ling Lin

2008-01-01

18

Defluorination of Aqueous Perfluorooctanesulfonate by Activated Persulfate Oxidation  

PubMed Central

Activated persulfate oxidation technologies based on sulfate radicals were first evaluated for defluorination of aqueous perfluorooctanesulfonate (PFOS). The influences of catalytic method, time, pH and K2S2O8 amounts on PFOS defluorination were investigated. The intermediate products during PFOS defluorination were detected by using LC/MS/MS. The results showed that the S2O82? had weak effect on the defluorination of PFOS, while the PFOS was oxidatively defluorinated by sulfate radicals in water. The defluorination efficiency of PFOS under various treatment was followed the order: HT (hydrothermal)/K2S2O8 > UV (ultraviolet)/K2S2O8 > Fe2+/K2S2O8 > US (ultrasound)/K2S2O8. Low pH was favorable for the PFOS defluorination with sulfate radicals. Increase in the amount of S2O82? had positive effect on PFOS defluorination. However, further increase in amounts of S2O82? caused insignificant improvement in PFOS defluorination due to elimination of sulfate radicals under high concentration of S2O82?. CF3(CF2)nCOOH (n?=?0–6) were detected as intermediates during PFOS defluorination. Sulfate radicals oxidation and hydrolysis were the main mechanisms involved in defluorination process of PFOS. PMID:24116016

Yang, Shewei; Cheng, Jianhua; Sun, Jian; Hu, Yongyou; Liang, Xiaoyan

2013-01-01

19

Oxidative degradation of propachlor by ferrous and copper ion activated persulfate.  

PubMed

The process of in situ chemical oxidation (ISCO) by persulfate (S(2)O(8)(2-)) can be accelerated by metal ion activation, which more effectively degrades subsurface pollutants by enhancing sulfate radical (SO(4)(-)) generation. This study compared the results of propachlor degradation by Cu(2+) and Fe(2+) activated persulfate and revealed differing degradation kinetics and mechanisms between the two types of activation system. The activation of persulfate by Fe(2+) ions generally resulted in rapid degradation in the early stage, but was accompanied by a dramatic decrease in efficiency due to the rapid depletion of Fe(2+) by the sulfate radicals generated. In contrast, the Cu(2+) activated persulfate had a longer lasting degradation effect and a proportionally greater degradation enhancement at elevated Cu(2+) concentrations. An optimal Fe(2+) concentration should be sought to activate the persulfate, as a high Fe(2+) concentration of 2.5mM or above, as was used in this study, may inhibit propachlor degradation due to the competitive consumption of sulfate radicals by the excess Fe(2+) ions. Higher temperatures (55°C compared with 30°C) resulted in enhanced metal activation, particularly with the Cu(2+) activated system. Furthermore, acidic conditions were found to be more favorable for propachlor degradation by metal activated persulfate. The ecotoxicity of degraded propachlor samples, which was indicated by average well color development (AWCD) for its microbial community activity, was confirmed to be decreased during the degradation processes with these two ions activated persulfate. PMID:22226398

Liu, C S; Shih, K; Sun, C X; Wang, F

2012-02-01

20

Modeling the oxidation kinetics of sono-activated persulfate's process on the degradation of humic acid.  

PubMed

Ultrasound degradation of humic acid has been investigated in the presence of persulfate anions at ultrasonic frequency of 40 kHz. The effects of persulfate anion concentration, ultrasonic power input, humic acid concentration, reaction time, solution pH and temperature on humic acid removal efficiency were studied. It is found that up to 90% humic acid removal efficiency was achieved after 2 h reaction. In this system, sulfate radicals (SO??·) were considered to be the mainly oxidant to mineralize humic acid while persulfate anion can hardly react with humic acid directly. A novel kinetic model based on sulfate radicals (SO??·) oxidation was established to describe the humic acid mineralization process mathematically and chemically in sono-activated persulfate system. According to the new model, ultrasound power, persulfate dosage, solution pH and reaction temperature have great influence on humic acid degradation. Different initial concentration of persulfate anions and humic acid, ultrasonic power, initial pH and reaction temperature have been discussed to valid the effectiveness of the model, and the simulated data showed new model had good agreement with the experiments data. PMID:25465096

Songlin, Wang; Ning, Zhou; Si, Wu; Qi, Zhang; Zhi, Yang

2015-03-01

21

Methyl tert-butyl ether (MTBE) degradation by ferrous ion-activated persulfate oxidation: feasibility and kinetics studies.  

PubMed

The objective of this study was to evaluate the feasibility of using ferrous ion-activated persulfate oxidation to remediate groundwater contaminated with methyl tert-butyl ether (MTBE). In this study, batch experiments were conducted to evaluate the effects of various factors on the efficiency of MTBE degradation including persulfate concentrations, ferrous ion concentrations, and persulfate coupled with hydrogen peroxide. Results show that ferrous ion-activated persulfate oxidation was capable of degrading MTBE efficiently. Persulfate and ferrous ion concentrations correlated with MTBE degradation rates. However, excess addition of ferrous ion resulted in decreased MTBE degrading rates most likely because of competition for sulfate free radicals between ferrous ion and MTBE. Two main byproducts of MTBE degradation, tert-butyl formate and tert-butyl alcohol, were detected in the experiments; both were, however, subsequently degraded. Results of sulfate analysis show that proper addition of ferrous ion could prevent unnecessary persulfate decomposition. PMID:19691249

Chen, K F; Kao, C M; Wu, L C; Surampalli, R Y; Liang, S H

2009-07-01

22

Measurement of dissolved organic carbon by wet chemical oxidation with persulfate: influence of chloride concentration and reagent volume  

Microsoft Academic Search

The influence of chloride content and reagent volume on the analysis of dissolved organic carbon by wet chemical oxidation with persulfate was evaluated. A strong hyperbolic relationship was found between measured DOC concentration and volume of persulfate added for oxidation in both marine and artificially chlorinated (NaCl) freshwater samples. Freshwater samples showed no such relationship. Precision of measured DOC concentrations

James H. McKenna; Peter H. Doering

1995-01-01

23

Total dissolved nitrogen analysis: comparisons between the persulfate, UV and high temperature oxidation methods  

Microsoft Academic Search

We compared the persulfate (PO), ultraviolet (UV), and high temperature oxidation (HTO) methods used to analyze total dissolved nitrogen (TDN) concentrations in aquatic samples to determine whether the three methods differed in terms of standard parameters (blanks, limits of detection and linearity, and precision) or in oxidation efficiency of standard compounds and field samples of varying salinity. The TDN concentrations

Deborah A. Bronk; Michael W. Lomas; Patricia M. Glibert; Karyn J. Schukert; Marta P. Sanderson

2000-01-01

24

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

EPA Science Inventory

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 ...

25

Kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE)  

Microsoft Academic Search

The kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE) in aqueous solutions at various pH, temperature, oxidant concentration and ionic strength levels was studied. The MTBE degradation was found to follow a pseudo-first-order decay model. The pseudo-first-order rate constants of MTBE degradation by persulfate (31.5 mM) at pH 7.0 and ionic strength 0.11 M are ?0.13×10?4, 0.48×10?4, 2.4×10?4

Kun-Chang Huang; Richard A Couttenye; George E Hoag

2002-01-01

26

Persulfate oxidation regeneration of granular activated carbon: reversible impacts on sorption behavior.  

PubMed

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 of sodium persulfate residuals in the GAC. In this study, we investigated the impact of chemical oxidation on the sorption characteristics of methyl-tert butyl ether (MTBE) in GAC. Loss of MTBE sorption was measured in thermally-activated persulfate regenerated GAC. The accumulation of sulfur was partially responsible for the blockage of sorption sites, but sorption loss was amplified under oxidizing and acidic conditions and attributed to the formation of acidic surface oxides and enhanced electrostatic attraction and accumulation of SO(4)(2-) in GAC. Raising the pH in the GAC slurry resulted in the removal of the residual sulfate and improved MTBE sorption indicating that the mechanisms responsible for MTBE sorption loss were reversible. These results establish baseline conditions and parameters that can be used to optimize pilot- and full-scale deployment of thermally-activated persulfate regeneration of GAC. PMID:22921651

Hutson, Andy; Ko, Saebom; Huling, Scott G

2012-11-01

27

Comparative Study on Oxidative Treatments of NAPL Containing Chlorinated Ethanes and Ethenes using Hydrogen Peroxide and Persulfate in Soils  

EPA Science Inventory

The goal of this study was to assess the oxidation of NAPL in soil, 30% of which were composed of chlorinated ethanes and ethenes, using catalyzed hydrogen peroxide (CHP), activated persulfate (AP), and H2O2?persulfate (HP) co-amendment systems. Citrate, a buffer and iron ligand,...

28

Influence of pH on persulfate oxidation of TCE at ambient temperatures  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technology used for groundwater remediation. This laboratory study investigated the use of the oxidant sodium persulfate for the chemical oxidation of trichloroethylene (TCE) at near ambient temperatures (10, 20 and 30°C) to determine the influence of pH (pH=4, 7 and 9) on the reaction rate (i.e., pseudo-first-order rate constants) over the range of

Chenju Liang; Zih-Sin Wang; Clifford J. Bruell

2007-01-01

29

Influences of carbonate and chloride ions on persulfate oxidation of trichloroethylene at 20 degrees C.  

PubMed

Application of in situ chemical oxidation (ISCO) involves application of oxidants to contaminants such as trichloroethylene (TCE) in soil or groundwater in place. Successful application of ISCO at a hazardous waste site requires understanding the scavenging reactions that could take place at the site to better optimize the oxidation of target contaminants and identification of site conditions where ISCO using persulfate may not be applicable. Additionally, estimation of the oxidant dose at a site would need identification of groundwater constituents such as alkalinity and chlorides that may scavenge radicals and therefore use up the oxidant that is targeted for the contaminant(s). The objective of this study was to investigate the influence of various levels of chloride and carbonates on persulfate oxidation of TCE at 20 degrees C under controlled conditions in a laboratory. Based on the results of the laboratory experiments, both chloride and alkalinity were shown to have scavenging effects on the rate of oxidation of TCE. It was found that at a neutral pH, persulfate oxidation of TCE was not affected by the presence of bicarbonate/carbonate concentrations within the range of 0-9.20 mM. However, the TCE degradation rate was seen to reduce with an increase in the level of carbonate species and at elevated pHs. TCE degradation in the presence of chlorides revealed no effect on the degradation rate especially at chloride levels below 0.2 M. However, at chloride levels greater than 0.2 M, TCE degradation rate was seen to reduce with an increase in the chloride ion concentration. Prior to application of persulfate as an oxidant, a site should be screened for the presence of scavengers to evaluate the potential of meeting target cleanup goals within a desirable timeframe at the site. PMID:17014891

Liang, Chenju; Wang, Zih-Sin; Mohanty, Nihar

2006-11-01

30

Persulfate oxidation for in situ remediation of TCE. II. Activated by chelated ferrous ion  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technique used to remediate contaminated soil and groundwater systems. It has been postulated that sodium persulfate (Na2S2O8) can be activated by transition metal ions such as ferrous ion (Fe2+) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a redox potential of 2.6 V, which can potentially destroy organic

Chenju Liang; Clifford J Bruell; Michael C Marley; Kenneth L Sperry

2004-01-01

31

kinetics and mechanism of the oxidation of uranium(iv) by persulfate ions in perchloric acid solutions  

SciTech Connect

The kinetics of the oxidation of uranium(IV) by persulfate ions in perchloric acid solutions was studied by a spectrophotometric method. It was established that the oxidation of uranium(IV) ions occurs along three pathways: directly by S/sub 2/O /SUP 2/8/ /sup -/ ions, by products of their thermal decomposition, and intramolecularly in a persulfate complex. It was shown that the contribution of each of the three pathways to the overall rate of oxidation of uranium(IV) depends on the initial reagent concentrations, the hydrogen ion concentration, and the temperature. The activation energies of the oxidation of uranium(IV) directly by persulfate ions, by products of their thermal decomposition, as well as in a persulfate complex, were determined.

Ermakov, V.A.

1986-07-01

32

Molecular Structure of Sodium persulfate  

NSDL National Science Digital Library

Sodium persulfate is an etchant and oxidizer. Oxidizers are highly reactive chemicals that can be used to clean or to render a metal surface free from corrosion. It is a crystalline or powdery solid at room temperature. Sodium persulfate is commonly used today as a replacement for ammonium persulfate in the etching of metal and semi-conductor surfaces.

2002-10-01

33

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate–thiosulfate redox couple  

Microsoft Academic Search

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82?) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a standard redox potential of 2.6 V. The SO4? is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE).

Chenju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2004-01-01

34

In situ chemical oxidation of contaminated groundwater by persulfate: decomposition by Fe(III)- and Mn(IV)-containing oxides and aquifer materials.  

PubMed

Persulfate (S2O8(2-)) is being used increasingly for in situ chemical oxidation (ISCO) of organic contaminants in groundwater, despite an incomplete understanding of the mechanism through which it is converted into reactive species. In particular, the decomposition of persulfate by naturally occurring mineral surfaces has not been studied in detail. To gain insight into the reaction rates and mechanism of persulfate decomposition in the subsurface, and to identify possible approaches for improving its efficacy, the decomposition of persulfate was investigated in the presence of pure metal oxides, clays, and representative aquifer solids collected from field sites in the presence and absence of benzene. Under conditions typical of groundwater, Fe(III)- and Mn(IV)-oxides catalytically converted persulfate into sulfate radical (SO4(•-)) and hydroxyl radical (HO(•)) over time scales of several weeks at rates that were 2-20 times faster than those observed in metal-free systems. Amorphous ferrihydrite was the most reactive iron mineral with respect to persulfate decomposition, with reaction rates proportional to solid mass and surface area. As a result of radical chain reactions, the rate of persulfate decomposition increased by as much as 100 times when benzene concentrations exceeded 0.1 mM. Due to its relatively slow rate of decomposition in the subsurface, it can be advantageous to inject persulfate into groundwater, allowing it to migrate to zones of low hydraulic conductivity where clays, metal oxides, and contaminants will accelerate its conversion into reactive oxidants. PMID:25133603

Liu, Haizhou; Bruton, Thomas A; Doyle, Fiona M; Sedlak, David L

2014-09-01

35

The Persulfate Process for the Mediated Oxidation of Organic Pollutants  

NASA Astrophysics Data System (ADS)

The electrochemical treatment of effluents with conventional anodic materials is not very efficient in terms of organic pollutant oxidation and produces a large amount of oxygen. These results can be enhanced by mediated oxidation that produces stronger oxidants than oxygen which oxidize the organic pollutants. New electrode materials like, boron-doped diamond (BDD) shows a high selectivity toward organic pollutants and the oxygen is not easily produced. Consequently the contribution of mediated oxidation cannot be excluded, but probably occurs in a different way. This chapter re-examines at the light of the present knowledge the mediated oxidation with the BDD anode, tests the used mediated oxidation method, and proposes an alternative method to increase the positive contribution of this oxidation during electrochemical treatment with BDD anodes.

Vatistas, N.; Comninellis, Ch.

36

Chemical Oxidation of Complex PAH Mixtures by Base-activated Sodium Persulfate  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) is an attractive approach for the remediation of recalcitrant soil and groundwater contaminants. One oxidant that has received significant recent attention is sodium persulfate, which has several advantages, including a relatively long lifetime in porous media, the ability to destroy a wide-range of chemical contaminants, and a high oxidation potential. In this study, we investigated the chemical mechanisms associated with base-activated persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) and assessed the applicability of persulfate to the remediation of porous media contaminated with non-aqueous phase liquid (NAPL) PAH mixtures. Batch experiments were conducted to determine the oxidation kinetics for individual PAH compounds, synthetic PAH mixtures, and manufactured gas plant (MGP) tars. Additional experiments were conducted with added surfactants (Triton X-100, Triton X-45, and Tween 80) to increase PAH mass transfer from the NAPL to the aqueous phase, and with radical scavengers (ethanol and tert-butyl alcohol) to identify the reactive species responsible for degradation. Degradation of total PAHs in the NAPL experiments was as high as 70%. The addition of surfactant increased initial PAH degradation rates, but also greatly increased the rate of base consumption, thereby reducing the overall fraction degraded. The degradation of individual PAHs within the NAPLs varied significantly, with the masses of some compounds remaining largely unchanged. The results of the radical scavenger and single PAH experiments suggest that the observed pattern of degradation in PAH mixtures is the result of a combination of mass transfer considerations and competition for radical species.

Hauswirth, S.; Miller, C. T.

2013-12-01

37

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

SciTech Connect

Highlights: ? Ozone and persulfate reagent (O{sub 3}/S{sub 2}O{sub 8}{sup 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{sub 3}–N was 72%, 96%, and 76%, respectively. ? A good value of ozone consumption (OC) obtained with 0.60 (kg O{sub 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 (<0.0001): COD, color, NH{sub 3}–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m{sup 3} ozone, 1 g/1 g COD{sub 0}/S{sub 2}O{sub 8}{sup 2-} ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH{sub 3}–N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O{sub 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{sub 2}O{sub 8}{sup 2-} only, to evaluate its effectiveness. The combined method (i.e., O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) achieved higher removal efficiencies for COD, color, and NH{sub 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.

Abu Amr, Salem S. [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Aziz, Hamidi Abdul, E-mail: cehamidi@eng.usm.my [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Adlan, Mohd Nordin [School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

2013-06-15

38

Ultrasonic-assisted chemical oxidative cutting of multiwalled carbon nanotubes with ammonium persulfate in neutral media  

NASA Astrophysics Data System (ADS)

A new, facile, and mild approach was developed to cut the conventional long and entangled multiwalled carbon nanotubes (MWCNTs) to short and dispersed ones with length of less than 1 ?m by ultrasonic-assisted chemical oxidation with ammonium persulfate (APS) in neutral aqueous solution at room temperature. The resulting products were characterized with Fourier transform infrared (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscope (TEM) techniques. The shortened MWCNTs formed stable dispersion state in water without the help of surfactants that provided possibility for further functionalizations and applications.

Liu, Peng; Wang, Tingmei

2009-12-01

39

One-pot synthesis of conducting polymer-coated latex particles: ammonium persulfate as free radical initiator and chemical oxidant.  

PubMed

Conducting polymer-coated polystyrene latex particles were synthesized in one pot using ammonium persulfate as an initiator for free radical polymerization of styrene and a chemical oxidant for chemical oxidative polymerization. Pressed pellets of the core-shell particles showed an efficient electrical conduction. PMID:20820522

Fujii, Syuji; Matsuzawa, Soichiro; Nakamura, Yoshinobu

2010-10-14

40

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.  

PubMed

In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. PMID:24220194

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-12-15

41

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

EPA Science Inventory

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...

42

Influence of pH on persulfate oxidation of TCE at ambient temperatures.  

PubMed

In situ chemical oxidation (ISCO) is a technology used for groundwater remediation. This laboratory study investigated the use of the oxidant sodium persulfate for the chemical oxidation of trichloroethylene (TCE) at near ambient temperatures (10, 20 and 30 degrees C) to determine the influence of pH (pH=4, 7 and 9) on the reaction rate (i.e., pseudo-first-order rate constants) over the range of temperatures utilized. TCE solutions (60 mg l(-1); 0.46 mM) were prepared in phosphate buffered RO water and a fixed persulfate/TCE molar ratio of 50/1 was employed in all tests. Half-lives of TCE degradation at 10, 20 and 30 degrees C (pH 7) were 115.5, 35.0 and 5.5h, respectively. Maximum TCE degradation occurred at pH 7. Lowering system pH resulted in a greater decrease in TCE degradation rates than increasing system pH. Radical scavenging tests used to identify predominant radical species suggested that the sulfate radical (SO(4)(.-)) predominates under acidic conditions and the hydroxyl radical (.OH) predominates under basic conditions. In a side by side comparison of TCE degradation in a groundwater vs. unbuffered RO water it was demonstrated that when the system pH is buffered to near neutral pH conditions due to the presence of natural occurring groundwater constituents that the TCE degradation rate is higher than in unbuffered RO water where the system pH dropped from 5.9 to 2.8. The results of this study suggest that in a field application of ISCO, pH should be monitored and adjusted to near neutral if necessary. PMID:16814844

Liang, Chenju; Wang, Zih-Sin; Bruell, Clifford J

2007-01-01

43

Mechanism of base activation of persulfate.  

PubMed

Base is the most commonly used activator of persulfate for the treatment of contaminated groundwater by in situ chemical oxidation (ISCO). A mechanism for the base activation of persulfate is proposed involving the base-catalyzed hydrolysis of persulfate to hydroperoxide anion and sulfate followed by the reduction of another persulfate molecule by hydroperoxide. Reduction by hydroperoxide decomposes persulfate into sulfate radical and sulfate anion, and hydroperoxide is oxidized to superoxide. The base-catalyzed hydrolysis of persulfate was supported by kinetic analyses of persulfate decomposition at various base:persulfate molar ratios and an increased rate of persulfate decomposition in D(2)O vs H(2)O. Stoichiometric analyses confirmed that hydroperoxide reacts with persulfate in a 1:1 molar ratio. Addition of hydroperoxide to basic persulfate systems resulted in rapid decomposition of the hydroperoxide and persulfate and decomposition of the superoxide probe hexachloroethane. The presence of superoxide was confirmed with scavenging by Cu(II). Electron spin resonance spectroscopy confirmed the generation of sulfate radical, hydroxyl radical, and superoxide. The results of this research are consistent with the widespread reactivity reported for base-activated persulfate when it is used for ISCO. PMID:20704244

Furman, Olha S; Teel, Amy L; Watts, Richard J

2010-08-15

44

Thermally Activated Persulfate Oxidation of Trichloroethylene (TCE) and 1,1,1Trichloroethane (TCA) in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Under thermally activated conditions (i.e., temperature of 40?99°C), there is considerable evidence that the persulfate anion () can be converted to a powerful oxidant known as the sulfate free radical (), which could be used in situ to destroy groundwater contaminants. In this laboratory study only limited trichloroethylene (TCE) degradation and no 1,1,1-trichloroethane (TCA) degradation was observed at 20°C. However,

Chen Ju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2003-01-01

45

Amorphous and condensed organic matter domains: the effect of persulfate oxidation on the composition of soil\\/sediment organic matter  

Microsoft Academic Search

The composition of amorphous and condensed soil\\/sediment organic matter (SOM) domains was investigated for one soil sample and four sediment samples. These samples were oxidized with persulfate to remove amorphous SOM, before and after which the composition of SOM was studied by thermogravimetric analysis, pyrolysis-GC\\/MS, and cross polarization magic angle spinning 13C-NMR. Comparison of the SOM composition before and after

Chiel Cuypers; Tim Grotenhuis; Klaas G. J. Nierop; Elena Maneiro Franco; Adrie de Jager; Wim Rulkens

2002-01-01

46

Novel insights into enhanced dewaterability of waste activated sludge by Fe(II)-activated persulfate oxidation.  

PubMed

The potential of Fe(II)-activated persulfate (S(2)O(8)(2-)) oxidation on enhancing the dewaterability of sludge flocs from 3-full scale wastewater treatment plants (WWTPs) were investigated. Normalized capillary suction time (CST) was applied to evaluate sludge dewaterability. Both extracellular polymeric substances (EPS) and metabolic activity of microorganisms were determined to explore the responsible mechanism. Fe(II)-S(2)O(8)(2-) oxidation effectively improved sludge dewaterability. The most important mechanisms were proposed to be the degradation of EPS incorporated in sludge flocs and rupture of microbial cells. Three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy confirmed that the powerful SO(4)(-) from Fe(II)-S(2)O(8)(2-) system destroyed the particular functional groups of fluorescing substances (i.e., aromatic protein-, tryptophan protein-, humic- and fulvic-like substances) in EPS and caused cleavage of linkages in the polymeric backbone and simultaneous destruction of microbial cells, resulting in the release of EPS-bound water, intracellular materials and water of hydration inside cells, and subsequent enhancement of dewaterability. PMID:22728175

Zhen, Guangyin; Lu, Xueqin; Li, Yuyou; Zhao, Youcai; Wang, Baoying; Song, Yu; Chai, Xiaoli; Niu, Dongjie; Cao, Xianyan

2012-09-01

47

Persulfate activation by subsurface minerals  

NASA Astrophysics Data System (ADS)

Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (< 7) and high pH (> 12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems.

Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

2010-06-01

48

Persulfate activation by subsurface minerals.  

PubMed

Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (<7) and high pH (>12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems. PMID:20439128

Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2010-06-25

49

Studies on oxidative radiolysis of ibuprofen in presence of potassium persulfate  

NASA Astrophysics Data System (ADS)

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 (K2S2O8). 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 K2S2O8, required much lesser dose compared to in the absence of K2S2O8 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 K2S2O8. It was found that unlike OH radical, SO4- 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 K2S2O8 could be one of the efficient advanced oxidation processes for degradation of pharmaceutical compounds present in the aqueous solution.

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

2014-07-01

50

Mechanism of persulfate activation by phenols.  

PubMed

The activation of persulfate by phenols was investigated to further the understanding of persulfate chemistry for in situ chemical oxidation (ISCO). Phenol (pKa = 10.0) activated persulfate at pH 12 but not at pH 8, suggesting activation occurred only via the phenoxide form. Evaluation of the phenoxide activation mechanism was complicated by the concurrent activation of persulfate by hydroperoxide anion, which is generated by the base catalyzed hydrolysis of persulfate. Therefore, phenoxide activation was investigated using pentachlorophenoxide at pH 8.3, midway between the pKa of pentachlorophenol (pKa = 4.8) and that of hydrogen peroxide (pKa = 11.8). Of the two possible mechanisms for phenoxide activation of persulfate (reduction or nucleophilic attack) the results were consistent with reduction of persulfate by phenoxide with oxidation of the phenoxide. The concentration of phenoxide required for maximum persulfate activation was low (1 mM). The results of this research document that phenoxides activate persulfate via reduction; phenolic moieties ubiquitous to soil organic matter in the subsurface may have a significant role in the activation of persulfate during its injection into the subsurface for ISCO. Furthermore, the results provide the foundation for activation of persulfate by other organic anions without the toxicity of phenols, such as keto acids. PMID:23663058

Ahmad, Mushtaque; Teel, Amy L; Watts, Richard J

2013-06-01

51

Ammonium persulfate: a safe alternative oxidizing reagent for measuring urinary iodine  

Microsoft Academic Search

The chioric acid method is most commonly used to obtain accurate and reproducible measurements of iodine and remove interfering substances. Unfortunately, chioric acid is a potential hazard, requiring an explosion-proof hood, among other precautions. We have developed a simple, convenient, and economic method for measuring urinary iodine by using 1 mol\\/L anunonium persulfate, a nonexplo- sive, nonhazardous chemical, as the

SAM PINO; SHIH-LIEH FANG; E. BRAVERMAN

52

Catalytic effects of copper(II) oxide and zinc(II) oxide on the thermal transitions of sodium and potassium persulfates  

Microsoft Academic Search

The thermal transitions of Na2S2O8 and K2S2O8 have been studied by means of a derivatograph in the presence of CuO or ZnO at various molar mixtures. A slight shift in the DTG peak of the first decomposition stage (persulfate into pyrosulfate) to higher temperature was noticed as the amount of oxide increases.

M. M. Barbooti; F. Jasim

1978-01-01

53

Remediation of phenanthrene-contaminated soil by simultaneous persulfate chemical oxidation and biodegradation processes.  

PubMed

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds with carcinogenic and/or mutagenic potential. To address the limitations of individual remediation techniques and to achieve better PAH removal efficiencies, the combination of chemical and biological treatments can be used. The degradation of phenanthrene (chosen as a model of PAH) by persulfate in freshly contaminated soil microcosms was studied to assess its impact on the biodegradation process and on soil properties. Soil microcosms contaminated with 140 mg/kgDRY SOIL of phenanthrene were treated with different persulfate (PS) concentrations 0.86-41.7 g/kgDRY SOIL and incubated for 28 days. Analyses of phenanthrene and persulfate concentrations and soil pH were performed. Cultivable heterotrophic bacterial count was carried out after 28 days of treatment. Genetic diversity analysis of the soil microcosm bacterial community was performed by PCR amplification of bacterial 16S rDNA fragments followed by denaturing gradient gel electrophoresis (DGGE). The addition of PS in low concentrations could be an interesting biostimulatory strategy that managed to shorten the lag phase of the phenanthrene biological elimination, without negative effects on the physicochemical and biological soil properties, improving the remediation treatment. PMID:24595755

Mora, Verónica C; Madueño, Laura; Peluffo, Marina; Rosso, Janina A; Del Panno, María T; Morelli, Irma S

2014-06-01

54

Treatment of tetrachloroethylene-contaminated groundwater by surfactant-enhanced persulfate/BOF slag oxidation--a laboratory feasibility study.  

PubMed

The main objective of this study was to evaluate the feasibility of remediating tetrachloroethylene (PCE)-contaminated groundwater (with initial PCE concentration of approximately 20 mg L(-1)) via persulfate oxidation activated by basic oxygen furnace slag (S(2)O(8)(2-)/BOF slag) with the addition of biodegradable surfactant (Tween 80). Results indicate that only 15% of PCE can be removed in experiment with the addition of S(2)O(8)(2-) only (S(2)O(8)(2-)/PCE=30/1). PCE removal can be increased to 31% while both S(2)O(8)(2-) and BOF slag (10 g L(-1)) were added. This indicates that BOF slag was able to activate the persulfate oxidation mechanism, and cause the decrease in PCE concentration via oxidation process. Results also reveal that PCE degradation rates increased to 92% with the presence of Tween 80 (S(2)O(8)(2-)/Tween 80/PCE=30/2/1). In the presence of 10 g L(-1) BOF slag, the reaction rate constant (k(obs)) values were found to be 3.1 x 10(-3), 8.7 x 10(-3), 1.6 x 10(-2), and 5.8 x 10(-2)h(-1), as the S(2)O(8)(2-)/Tween 80/PCE molar ratios were 30/0/1, 30/0.5/1, 30/1/1, and 30/2/1, respectively. The reaction rate constant increased as the Tween 80 concentration increased. The significantly increased k(obs) could be caused by the enhanced solubilization of PCE by Tween 80. The increase in initial surfactant concentration would cause the increase in the solubilization of PCE, and thus, enhance the oxidation rate. This was confirmed by the total amount of chloride ions produced after the reaction. Results from this study indicate that BOF slag-activated persulfate oxidation enhanced by surfactant addition is a potential method to efficiently and effectively remediate chlorinated solvents contaminated groundwater. PMID:19586715

Tsai, T T; Kao, C M; Hong, A

2009-11-15

55

Ultraviolet-activated persulfate oxidation of methyl orange: a comparison between artificial neural networks and factorial design for process modelling.  

PubMed

In this work, the degradation of the azo dye methyl orange in model aqueous solutions by UVC light-induced persulfate oxidation was studied. Five operating parameters that may influence the decolorization kinetics were evaluated, namely, methyl orange (MO) (5-50 mg L(-1)) and sodium persulfate (SPS) (50-150 mg L(-1)) concentration, reaction time (up to 60 min), (un-buffered) solution pH (3-9) and the addition of NaCl (0-500 mg L(-1)). The process was simulated, applying and comparing two methodologies, namely two-level factorial design and an artificial neural network (ANN). It was found that MO concentration is the most influential parameter, followed by the reaction time and SPS concentration, while the effects of solution pH and the addition of sodium chloride are statistically less significant; this order of significance was predicted by both methodologies. The ANN can simulate the process more accurately (i.e. in terms of R(2), mean square error (MSE) and residuals) than factorial design, although it needs significantly larger sets of data and longer computational time. PMID:25338014

Frontistis, Zacharias; Hapeshi, Evroula; Fatta-Kassinos, Despo; Mantzavinos, Dionissios

2015-03-01

56

Persulfate persistence under thermal activation conditions.  

PubMed

Contaminant destruction with in situ chemical oxidation (ISCO) using persulfate (peroxydisulfate, S2O8(2-)) can be enhanced by activation, which increases the rate of persulfate decomposition to sulfate radicals (SO4*-). This step initiates a chain of radical reactions involving species (including SO4*- and OH*) that oxidize contaminants more rapidly than persulfate does directly. Among current activation methods, thermal activation is the least well studied. Combining new data for environmentally relevant conditions with previously published data, we have computed three sets of Arrhenius parameters (In A and Eact) that describe the rate of persulfate decomposition in homogeneous solutions over a wide range of temperature and pH. The addition of soil increases the decomposition rate of persulfate due to reactions with organic matter and possibly mineral surfaces, but the kinetics are still pseudo-first-order in persulfate and conform to the Arrhenius model. A series of respike experiments with soil at 70 degrees C demonstrate that once the oxidant demand is met, reaction rates return to values near those observed in the homogeneous solution case. However, even after the oxidant demand is met, the relatively short lifetime of the persulfate at elevated temperatures (e.g., >50 degrees C) will limit the delivery time over which persulfate can be effective. PMID:19174915

Johnson, Richard L; Tratnyek, Paul G; Johnson, Reid O'Brien

2008-12-15

57

Evaluation of lead and COD removal from lead octoate drier effluent by chemical precipitation, coagulation–flocculation, and potassium persulfate oxidation processes  

Microsoft Academic Search

A range of treatment processes for the removal of mineral and organic pollutants from industrial wastewater have been investigated. This study was aimed to remove lead, turbidity, and chemical oxygen demand (COD) from lead octoate drier wastewater via potassium persulfate oxidation in the presence of UV and heat, chemical precipitation by sulfuric acid, and coagulation–flocculation processes. Al2(SO4)3, poly-aluminum chloride (PAC),

Anahita Rabii; Gholamreza Nabi Bidhendi; Naser Mehrdadi

2012-01-01

58

Persulfate activation by naturally occurring trace minerals.  

PubMed

The potential for 13 naturally occurring minerals to mediate the decomposition of persulfate and generate a range of reactive oxygen species was investigated to provide fundamental information on activation mechanisms when persulfate is used for in situ chemical oxidation (ISCO). Only four of the minerals (cobaltite, ilmenite, pyrite, and siderite) promoted the decomposition of persulfate more rapidly than persulfate-deionized water control systems. The other nine minerals decomposed persulfate at the same rate or more slowly than the control systems. Mineral-mediated persulfate activation was conducted with the addition of one of three probe compounds to detect the generation of reactive oxygen species: anisole (sulfate+hydroxyl radical), nitrobenzene (hydroxyl radical), and hexachloroethane (reductants and nucleophiles). The reduced mineral pyrite promoted rapid generation of sulfate+hydroxyl radical. However, the remainder of the minerals provided minimal potential for the generation of reactive oxygen species. The results of this research demonstrate that the majority of naturally occurring trace minerals do not activate persulfate to generate reactive oxygen species, and other mechanisms of activation are necessary to promote contaminant destruction in the subsurface during persulfate ISCO. PMID:21968122

Teel, Amy L; Ahmad, Mushtaque; Watts, Richard J

2011-11-30

59

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

PubMed

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. PMID:18649972

Liang, Chenju; Lee, I-Ling

2008-09-10

60

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

EPA Science Inventory

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...

61

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

EPA Science Inventory

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...

62

Persulfate Digestion and Simultaneous Colorimetric Analysis of Carbon and Nitrogen in Soil Extracts  

Microsoft Academic Search

Doyle and Schimel, 1998). Persulfate oxidation has been developed for soil extract DON (Cabrera and Persulfate digestions have been used for analyzing dissolved or- Beare, 1993) and for fresh water DOC (McDowell et ganic carbon (DOC) and nitrogen (DON), but most existing methods do not simultaneously analyze the same digest. Persulfate oxidizes al., 1987). It is conveniently run in an

Allen Doyle; Michael N. Weintraub; Joshua P. Schimel

2004-01-01

63

Transition-metal-free C-H oxidative activation: persulfate-promoted selective benzylic mono- and difluorination.  

PubMed

An operationally simple and selective method for the direct conversion of benzylic C-H to C-F to obtain mono- and difluoromethylated arenes using Selectfluor™ as a fluorine source is developed. Persulfate can be used to selectively activate benzylic hydrogen atoms toward C-F bond formation without the aid of transition metal catalysts. PMID:25645405

Ma, Jing-Jing; Yi, Wen-Bin; Lu, Guo-Ping; Cai, Chun

2015-02-24

64

Application of persulfate-releasing barrier to remediate MTBE and benzene contaminated groundwater.  

PubMed

The objective of this study was to assess the potential of using an in situ oxidation barrier system to remediate gasoline-contaminated groundwater. The passive remedial system included a persulfate-releasing barrier containing persulfate-releasing materials to release persulfate for contaminant oxidation. Bench experiments were performed to determine the components and persulfate-releasing rate of the persulfate-releasing materials. Column experiments were conducted to evaluate the effectiveness of the designed persulfate-releasing materials on the control of petroleum-hydrocarbon plume. In this study, methyl tert-butyl ether (MTBE) and benzene were used as the target compounds. The optimal persulfate releasing rate was obtained when the mass ratio of persulfate/cement/sand/water was 1/1/0.16/0.5, and the rate varied from 31 to 8 mg persulfate per day per g of material. Significant amounts of MTBE and benzene were removed through the oxidation process due to the release of persulfate, and the produced tert-butyl formate (TBF) and tert-butyl alcohol (TBA), byproducts of MTBE, were further oxidized in the system. Results suggest that the oxidation rate would be affected by the oxidant reduction potential and concentrations of ferrous iron and persulfate. PMID:21044818

Liang, S H; Kao, C M; Kuo, Y C; Chen, K F

2011-01-30

65

A rapid spectrophotometric determination of persulfate anion in ISCO.  

PubMed

Due to a gradual increase in the use of persulfate as an in situ chemical oxidation (ISCO) oxidant, a simple measurement of persulfate concentration is desirable to analyze persulfate distribution at designated time intervals on/off a site. Such a distribution helps evaluate efficacy of ISCO treatment at a site. This work proposes a spectrophotometric determination of persulfate based on modification of the iodometric titration method. The analysis of absorption spectra of a yellow color solution resulting from the reaction of persulfate and iodide in the presence of sodium bicarbonate reveals an absorbance at 352 nm, without significant interferences from the reagent matrix. The calibration graph was linear in the range of persulfate solution concentration of 0-70 mM at 352 nm. The proposed method is validated by the iodometric titration method. The solution pH was at near neutral and the presence of iron activator does not interfere with the absorption measurement. Also, analysis of persulfate in a groundwater sample using the proposed method indicates a good agreement with measurements by the titration method. This proposed spectrophotometric quantification of persulfate provides a simple and rapid method for evaluation of ISCO effectiveness at a remediation site. PMID:18922560

Liang, Chenju; Huang, Chiu-Fen; Mohanty, Nihar; Kurakalva, Rama Mohan

2008-11-01

66

Kinetics of the oxidation of iodide ion by persulfate ion in the critical water/bis(2-ethylhexyl) sodium sulfosuccinate/n-decane microemulsions.  

PubMed

In this work, we studied the kinetics of the oxidation of iodide ion by persulfate ion in the critical water/bis(2-ethylhexyl) sodium sulfosuccinate (AOT)/n-decane microemulsions with the molar ratios of water to AOT being 35.0 and 40.8 via the microcalorimetry at various temperatures. It was found that the Arrhenius equation was valid for correlating experimental measurements in the noncritical region, but the slowing down effect existed significantly in the near critical region. We determined the values of the critical slowing down exponent and found it to be 0.187 ± 0.023 and 0.193 ± 0.032, respectively, which agreed well with the theoretical value of 0.207 predicted by the Griffiths-Wheeler rule for the singularity of the dimer/monomer droplet equilibrium in the critical AOT/water/n-decane microemulsions. PMID:25348218

Yin, Handi; Du, Zhongyu; Zhao, Jihua; Shen, Weiguo

2014-11-13

67

Persulfate injection into a gasoline source zone  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

68

Persulfate injection into a gasoline source zone.  

PubMed

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. PMID:23660235

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

2013-07-01

69

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

PubMed

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. PMID:25193794

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

2014-12-01

70

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

EPA Science Inventory

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...

71

pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene  

NASA Astrophysics Data System (ADS)

The ability of free ferrous ion activated persulfate (S 2O 82-) to generate sulfate radicals (SO 4- rad ) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO 4- rad with excess Fe 2+ and a quick conversion of Fe 2+ to Fe 3+. This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe 3+ in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe 3+ and EDTA alone did not appreciably degrade persulfate. The presence of TCE in the EDTA/Fe 3+ activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S 2O 82- and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe 3+ molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe 3+ molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption.

Liang, Chenju; Liang, Ching-Ping; Chen, Chi-Chin

2009-05-01

72

Mineralization of aniline in aqueous solution by electrochemical activation of persulfate.  

PubMed

Oxidative degradation of aniline in aqueous solution was carried out by coupling electrolysis with persulfate oxidation, in which a synergistic effect occurred. Experiments were performed under a batch-wise mode to evaluate the influence of various operation parameters on the electrolytic behavior, such as acidity of aqueous solution, temperature, electrode potential, persulfate anion concentration and nitrogen/oxygen gas dosage. The aniline pollutants could be almost entirely mineralized by means of electro-activated persulfate oxidation, wherein sulfate radicals were presumed to be principal oxidizing agents. Besides, electrogenerated hydrogen peroxide originated from cathodic reduction of oxygen, supplied chiefly by anodic oxidation of water, would contribute partially for decomposition of aniline. On the whole, the electro-activated persulfate process is a very promising method for treatment of aniline in wastewater. PMID:25576128

Chen, Wen-Shing; Huang, Chi-Pin

2015-04-01

73

Sonochemical acceleration of persulfate decomposition  

Microsoft Academic Search

The decomposition kinetics of potassium persulfate in aqueous solution have been investigated using a radical trapping method. The use of ultrasound was found to markedly accelerate the decomposition so that the sonochemical process at 25°C occurs at the same rate as the purely thermal reaction at 55°C. The effect of ultrasound intensity has also been studied and can be used

Gareth J. Price; Andrew A. Clifton

1996-01-01

74

Potential for activated persulfate degradation of BTEX contamination  

Microsoft Academic Search

The present study focused on evaluation of activated persulfate (PS) anion (S2O82?) oxidative degradation of benzene, toluene, ethylbenzene, and xylene (constituents of gasoline and known collectively as BTEX) contamination. The results indicated that BTEX were effectively oxidized by PS in aqueous and soil slurry systems at 20°C. PS can be activated thermally, or chemically activated with Fe2+ to form the

Chenju Liang; Chiu-Fen Huang; Yan-Jyun Chen

2008-01-01

75

Agent neutralization studies III. Detoxification of VX in aqueous persulfate. Final report, May-August 1993  

SciTech Connect

Aqueous solutions of persulfate salts are frequently used to mineralize organic substrates in the course of total organic carbon analyses. A study has been conducted at the U.S. Army Edgewood Research, Development and Engineering Center to determine whether this approach may be useful to neutralize the nerve agent VX. VX was reacted with aqueous ammonium persulfate at 90 deg C and 70 deg C. The concentration of agent and the acidity of the mixture were varied. 31P-NMR was used to monitor the destruction of VX as well as the formation and degradation of the phosphorus-containing products. A titration procedure using ferrous sulfate and ceric ammonium nitrate was used to monitor the consumption of persulfate. The products formed and their stabilities were found to vary significantly with the acidity of the solution. Nuclear magnetic resonance, Oxidation, VX, Ammonium persulfate, Mineralization, Temperature effects, Chemical agent disposal.

Hovanec, J.W.; Albizo, J.M.; Henderson, V.D.; Szafraniec, L.L.; Beaudry, W.T.

1994-06-01

76

Solid State Cleavage of Semicarbazones and Phenylhydrazones with Ammonium Persulfate-Clay using Microwave or Ultrasonic Irradiation  

Microsoft Academic Search

Adsorbed on clay, semicarbazone and phenylhydrazone derivatives are oxidatively cleaved in solid state to generate the corresponding ketones by ammonium persulfate using microwave or ultrasonic irradiation. © 1997 Elsevier Science Ltd.

Rajender S Varma; Harshadas M Meshram

1997-01-01

77

Targeted proteomic analyses of nasal lavage fluid in persulfate-challenged hairdressers with bleaching powder-associated rhinitis.  

PubMed

Hairdressers have an increased risk for developing airway symptoms, for example, asthma and rhinitis. Persulfates, which are oxidizing agents in bleaching powder, are considered important causal agents for these symptoms. However, the underlying mechanisms are unclear. The aim was therefore to measure proteomic changes in nasal lavage fluid from persulfate-challenged subjects to identify proteins potentially involved in the pathogenesis of bleaching powder-associated rhinitis or candidate effect biomarkers for persulfate. Also, oxidized peptides were measured to evaluate their usefulness as biomarkers for persulfate exposure or effect, for example, oxidative stress. Samples from hairdressers with and without bleaching powder-associated rhinitis were analyzed with liquid chromatography tandem mass spectrometry using selected reaction monitoring to target 246 proteins and five oxidized peptides. Pathway analysis was applied to obtain a functional overview of the proteins. Several proteins involved in biologically meaningful pathways, functions, or disorders, for example, inflammatory responses, oxidative stress, epithelium integrity, and dermatological disorders, changed after the persulfate challenge. A list with nine proteins that appeared to be affected by the persulfate challenge and should be followed up was defined. An albumin peptide containing oxidized tryptophan increased 2 h and 5 h after the challenge but not after 20 min, which indicates that such peptides may be useful as oxidative stress biomarkers. PMID:25546367

Mörtstedt, Harriet; Ali, Neserin; Kåredal, Monica; Jacobsson, Helene; Rietz, Emelie; Kronholm Diab, Kerstin; Nielsen, Jörn; Jönsson, Bo A G; Lindh, Christian H

2015-02-01

78

Degradation of dimethyl phthalate in solutions and soil slurries by persulfate at ambient temperature.  

PubMed

The degradation of dimethyl phthalate (DMP) by persulfate at ambient temperature (T=20-40°C) was investigated in aqueous solutions and soil slurries to assess the feasibility of using persulfate to remediate DMP contaminated soil and groundwater. First, the effects of temperature, initial oxidant concentration, initial DMP concentration and initial solution pH on the removal of DMP and TOC were studied in aqueous solutions. The results show that persulfate at 40°C can effectively mineralize DMP. Furthermore, dimethyl 4-hydroxyl phthalate, maleic acid and oxalic acid were identified as the degradation intermediates, and degradation pathways were proposed. Lastly, persulfate at 40°C was applied to remediate soil spiked with DMP at ? 600 mg/kg. The results show that persulfate at 40°C is highly effective for the remediation of DMP contaminated soil. Overall, this study provides fundamental and practical knowledge for the treatment of emerging phthalate esters (PAEs) contaminated soil and groundwater, as well as PAEs contaminated industrial wastewater, with persulfate at ambient temperature. PMID:24637446

Wang, Zhen; Deng, Dayi; Yang, Liling

2014-04-30

79

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

PubMed Central

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

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

2014-01-01

80

Electrolysis cell for the manufacture of persulfates  

NASA Technical Reports Server (NTRS)

A cell for the electrolytic generation of persulfates, characterized by the fact that a housing acts as cathode, is made of metal, and consists of a lower electrolytically active section and an upper electrolytically inactive section. It is designed so that there is produced the greatest possible current density suited to produce the desired electrolysis effect. This invention, compared to the devices used until now, exhibits considerable advantages whereby it is particularly suited for the production of potassium persulfate.

Cueto, J. M.

1986-01-01

81

Leaching of Calcareous Bornite Ore in Ammoniacal Solution Containing Ammonium Persulfate  

NASA Astrophysics Data System (ADS)

The leaching process of copper from calcareous bornite ore using ammonium persulfate as an oxidant in ammoniacal solution was investigated. The effects of stirring speed, temperature, initial concentration of ammonia and ammonium persulfate, and liquid-to-solid (L/S) ratio on the extraction percentage of copper from bornite ore were studied. The results show that the optimum leaching conditions for bornite ore with a maximum extraction of copper 88.9 pct are temperature 313.15 K (40 °C), reaction time 4 hours, stirring speed 600 r /min, L/S ratio 7/1 cm3/g, initial concentration of ammonia 2.0 mol/dm3, and ammonium persulfate 3.0 mol/dm3.

Liu, Zhi-xiong; Yin, Zhou-lan; Chen, Yi-guang; Xiong, Li-zhi

2014-12-01

82

Advanced oxidation of the commercial nonionic surfactant octylphenol polyethoxylate TritonTM X-45 by the persulfate/UV-C process: effect of operating parameters and kinetic evaluation  

NASA Astrophysics Data System (ADS)

This study explored the potential use of a sulfate radical (SO4?-)-based photochemical oxidation process to treat the commercial nonionic surfactant octylphenol polyethoxylate (OPPE) TritonTMX-45. For this purpose, the effect of initial S2O82- (0-5.0 mM) and OPPE (10-100 mg/L) concentrations on OPPE and its organic carbon content (TOC) removal were investigated at an initial reaction pH of 6.5. Results indicated that very fast OPPE degradation (100%) accompanied with high TOC abatement rates (90%) could be achieved for 10 and 20 mg/L aqueous OPPE at elevated S2O82- concentrations (>2.5 mM). S2O82-/UV-C treatment was still capable of complete OPPE removal up to an initial concentration of 40 mg/L in the presence of 2.5 mM S2O82-. On the other hand, TOC removal efficiencies dropped down to only 40% under the same reaction conditions. S2O82-/UV-C oxidation of OPPE was also compared with the relatively well-known and established H2O2/UV-C oxidation process. Treatment results showed that the performance of S2O82-/UV-C was comparable to that of H2O2/UV-C oxidation for the degradation and mineralization of OPPE. In order to elucidate the relative reactivity and selectivity of SO4?- and HO?, bimolecular reaction rate coefficients of OPPE with SO4?- and HO? were determined by employing competition kinetics with aqueous phenol (47 ?M) selected as the reference compound. The first-order abatement rate coefficient obtained for OPPE during S2O82-/UV-C oxidation (0.044 min-1) was found to be significantly lower than that calculated for phenol (0.397 min-1). In the case of H2O2/UV-C oxidation however, similar first-order abatement rate coefficients were obtained for both OPPE (0.087 min-1) and phenol (0.140 min-1). Second-order reaction rate coefficients for OPPE with SO4?- and HO? were determined as 9.8?108 M-1s-1 and 4.1?109 M-1s-1, respectively. The kinetic study also revealed that the selectivity of SO4?- was found to be significantly higher than that of HO?.

Arslan-Alaton, Idil; Olmez-Hanci, Tugba; Genc, Bora; Dursun, Duygu

2013-03-01

83

Degradation of ciprofloxacin and sulfamethoxazole by ferrous-activated persulfate: implications for remediation of groundwater contaminated by antibiotics.  

PubMed

The wide occurrence of antibiotics in groundwater raised great scientific interest as well as public awareness in recent years due to their potential ability to spread antibiotic resistant gene and pose risk to humans. The present study investigated the ferrous ion (Fe(II)) activated decomposition of persulfate (S2O8(2-)), as a potential in situ chemical oxidation (ISCO) approach, for remediation of groundwater contaminated by antibiotics. Fe(II)-persulfate mediated ciprofloxacin (CIP) degradation was found to be more efficient than sulfamethoxazole (SMX) at near neutral pH (pH6.0), probably due to the higher electric density in CIP molecule and its ability to form complex with Fe(II) as a ligand. Hydroxyl (HO) and sulfate radical (SO4(-)) were determined to be responsible for the degradation of CIP and SMX in Fe(II)-persulfate system by molecular probes. No enhancement in the degradation of CIP was observed when citrate (CA), ethylenediaminetetraacetate (EDTA) and (S,S)-ethylenediamine-N,N'-disuccinate (EDDS) were used as Fe(II) chelating agents in Fe(II)-persulfate system. For SMX, CA and EDTA accelerated the degradation by Fe(II)-persulfate. Degradation of antibiotics in river water matrix was nearly the same as that in Milli-Q water, implying the possibility of using Fe(II)-persulfate for antibiotics depletion under environmentally relevant condition. A comparison of the degradation efficiency of SMX with other sulfonamides and sulfanilic acid indicated that the heterocyclic ring has a large impact on the degradation of sulfonamides. Transformation products of CIP and SMX by Fe(II)-persulfate were analyzed by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) technique. Based on the intermediate products, Fe(II)-persulfate mediated CIP degradation pathways were tentatively proposed. PMID:24342085

Ji, Yuefei; Ferronato, Corinne; Salvador, Arnaud; Yang, Xi; Chovelon, Jean-Marc

2014-02-15

84

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

E-print Network

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 21 soil) and low (9.3 g kg 21 soil) additions of sodium persulfate to a petroleum hydrocarbon-contaminated soil, as well as sand spiked with diesel. Recoveries of 9561 % and 96610 % were observed with the higher application rate in the contaminated soil and spiked sand, respectively. Corresponding recoveries of 8665 % and 117619 % 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.

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

2013-01-01

85

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

PubMed Central

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

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

2013-01-01

86

Developing slow-release persulfate candles to treat BTEX contaminated groundwater.  

PubMed

The development of slow-release chemical oxidants for sub-surface remediation is a relatively new technology. Our objective was to develop slow-release persulfate-paraffin candles to treat BTEX-contaminated groundwater. Laboratory-scale candles were prepared by heating and mixing Na(2)S(2)O(8) with paraffin in a 2.25 to 1 ratio (w/w), and then pouring the heated mixture into circular molds that were 2.38 cm long and either 0.71 or 1.27 cm in diameter. Activator candles were prepared with FeSO(4) or zerovalent iron (ZVI) and wax. By treating benzoic acid and BTEX compounds with slow-release persulfate and ZVI candles, we observed rapid transformation of all contaminants. By using (14)C-labeled benzoic acid and benzene, we also confirmed mineralization (conversion to CO2) upon exposure to the candles. As the candles aged and were repeatedly exposed to fresh solutions, contaminant transformation rates slowed and removal rates became more linear (zero-order); this change in transformation kinetics mimicked the observed dissolution rates of the candles. By stacking persulfate and ZVI candles on top of each other in a saturated sand tank (14×14×2.5 cm) and spatially sampling around the candles with time, the dissolution patterns of the candles and zone of influence were determined. Results showed that as the candles dissolved and persulfate and iron diffused out into the sand matrix, benzoic acid or benzene concentrations (C(o)=1 mM) decreased by >90% within 7 d. These results support the use of slow-release persulfate and ZVI candles as a means of treating BTEX compounds in contaminated groundwater. PMID:22776257

Kambhu, Ann; Comfort, Steve; Chokejaroenrat, Chanat; Sakulthaew, Chainarong

2012-10-01

87

Decolorization of an azo dye Orange G in microbial fuel cells using Fe(II)-EDTA catalyzed persulfate.  

PubMed

This study constructed a microbial fuel cell (MFC) using Fe(II)-EDTA catalyzed persulfate as the cathode solutions to decolorize Orange G (OG) and harvest electricity simultaneously. Chelated Fe(2+) could activate persulfate to generate sulfate free radicals (SO(4)(-)) which with high oxidation potential (E(0)=2.6 V) can degrade azo dyes. The influence of some important factors such as pH value of cathode solutions, dosages of K(2)S(2)O(8), Fe(2+) and EDTA were investigated in a two-chamber microbial fuel cell. Under an optimal condition, the maximum power density achieved 91.1 mW m(-2), the OG removal rate was 97.4% and the K(2)S(2)O(8) remaining rate was 47.3% after 12 h. The OG degradation by Fe(II)-EDTA catalyzed persulfate was found to follow the second-order kinetic model. PMID:23073095

Niu, Cheng-Gang; Wang, Ying; Zhang, Xue-Gang; Zeng, Guang-Ming; Huang, Da-Wei; Ruan, Min; Li, Xiang-Wei

2012-12-01

88

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

PubMed

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. PMID:25804531

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

2015-06-01

89

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...FMC''), a domestic producer of persulfates, requested that the Department...

2010-01-14

90

Polymer\\/silicate nanocomposites synthesized with potassium persulfate at room temperature: polymerization mechanism, characterization, and mechanical properties of the nanocomposites  

Microsoft Academic Search

Polymer\\/silicate nanocomposites were synthesized using potassium persulfate (KPS) in the presence of silicate and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) without exterior redox co-catalysts at a room temperature. A mechanism for the room temperature polymerization in the presence of silicate was suggested: AMPS attached on the surface of silicate layers would oxidize Fe+2 in silicate lattice to become Fe+3 and the Fe+3 would

Yeong Suk Choi; Hyeong Taek Ham; In Jae Chung

2003-01-01

91

78 FR 14591 - Persulfates From China; Correction to Notice of institution  

Federal Register 2010, 2011, 2012, 2013, 2014

...COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Correction to Notice of institution AGENCY...five-year review concerning the antidumping duty order on persulfates from China with an incorrect effective date....

2013-03-06

92

Free radical degradation of chitosan with potassium persulfate  

Microsoft Academic Search

A thermal dissociation initiator, potassium persulfate (KPS), is added to the chitosan solution at 70 °C; immediately, the solution viscosity and the molecular weight of chitosan decrease in a very short time. Size exclusion chromatography, nuclear magnetic resonance and electron spin resonance were used to study the degradation mechanism. A free radical degradation mechanism of chitosan by KPS is then proposed.

Shih-Chang Hsu; Trong-Ming Don; Wen-Yen Chiu

2002-01-01

93

Cocatalyst effect in potassium persulfate initiated grafting onto chitosan  

Microsoft Academic Search

Methyl methacrylate and methyl acrylate were grafted onto chitosan by using potassium persulfate alone as redox initiator and in combination with MnCl2 and CuCl2, as inorganic, and both ammonium tartrate and oxalate as organic cocatalysts. The extent of grafting was found to depend mainly on the nature of the cocatalysts used.

J. Retuert; M. Yazdani-Pedram

1993-01-01

94

Assessing acute toxicity potential of persulfate ISCO treated water.  

PubMed

Persulfate anion (S2O8(2-)), a widely used in situ chemical oxidation agent, is increasingly applied for environmental remediation. However, limited information on environmental and toxicological effects is available for the evaluation of the environmental risk of exposure to S2O8(2-), particularly after its application. In this study, the acute toxic effects on the common carp (Cyprinus carpio) were employed as a model to investigate S2O8(2-), sulfate ion (decomposition product of S2O8(2-)), hydrogen/hydroxide ions and also the mixtures of these ion species. Acute toxicity test results showed 96h median lethal concentrations (LC50) of 540±23mgL(-1) for S2O8(2-) and 4100±110mgL(-1) for SO4(2-). S2O8(2-) was considerably more toxic than its decomposition product SO4(2-). Additionally, solution pH was also an important factor influencing toxicity, and S2O8(2-) posed reduced acute toxicity when pH was in the range of 6-10. Water conductivity up to approximately 8000?Scm(-1) did not appear to significantly increase fish mortality. In the mixture toxicity test (i.e., S2O8(2-)/OH(-)), LC50 values of 130±10mgL(-1) for S2O8(2-) and 23±2mgL(-1) for OH(-) were lower than those obtained from the individual toxicity tests and therefore exhibited higher toxicity to fish. However, upon complete decomposition of S2O8(2-) in the mixture, a reduction in acute toxicity may be expected. The results of this study revealed that it may be necessary and/or desirable to control the residual S2O8(2-)and pH after S2O8(2-) addition when potential exposure to an aquatic system is a concern. PMID:24099898

Liang, Chenju; Wang, Chi-Wei

2013-11-01

95

Voltammetric determination of persulfate anions using an electrode modified with a Prussian blue film  

Microsoft Academic Search

Prussian blue [PB, iron(III) hexacyanoferrate(II)] films are effective for the electrocatalysis of the persulfate (peroxodisulfate)\\/sulfate redox system. This has been exploited in the voltammetric determination of persulfate anions using a PB-modified platinum disc electrode. A linear correlation between electrocatalytic current and persulfate concentration was found for the range 5×10?5 to 3×10?3 mol dm?3, using 0.100 mol dm?3 potassium chloride as

Marcelo F. de Oliveira; Roger J. Mortimer; Nelson R. Stradiotto

2000-01-01

96

Kinetics of radical-chain decomposition of persulfate in aqueous solutions of organic compounds  

SciTech Connect

The mechanism of the radical-chain decomposition of persulfate in an aqueous medium in the presence of organic compounds was analyzed in an inert atmosphere. It was found that with variation in the substrate or persulfate concentration over wide limits, there is a regular change in the partial orders of the reaction: The reaction order with respect to persulfate varies from 3/2 to 1, and that with respect to the substrate from 0 to 1.

Berlin, A.A

1986-07-01

97

Preparation of Mg-vermiculite nanoparticles using potassium persulfate treatment.  

PubMed

Delamination/exfoliation process of the Mg-vermiculite (Letovice, Czech Republic), particles with size less than 5 microm, was studied after potassium persulfate treatment and compared with known method utilized hydrogen peroxide treatment. X-ray powder diffraction (XRPD) patterns showed that treatment of Mg-vermiculite with different molar concentration of potassium persulfate: c = 0.02, 0.04, and 0.08 mol x dm(-3) at the temperature 60 degrees C for 2 hr caused reduction of relative intensity (I(rel.)) of the basal 001 diffraction to the 15%, 9%, and 4%, respectively, compared to intensity of 001 diffraction of untreated Mg-vermiculite (I(rel.) = 100%). On the other hand I(rel.) of the 001 diffraction of Mg-vermiculite after treatment with 30% and 50% (c = 9.8 and 17.4 mol x dm(-3)) hydrogen peroxide at the 60 degrees C for 2 hr decreased only to I(rel.) = 36% and 32%, respectively. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) verified effect of potassium persulfate treatment on structure degradation which is connected with higher degree of delamination/exfoliation of the particles and their cracking into nano-sized particles. PMID:17037860

Mat?jka, Vlastimil; Supová-Krístková, Monika; Kratosvá, Gabriela; Valásková, Marta

2006-08-01

98

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

NASA Astrophysics Data System (ADS)

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.

Deniz Turan, M.; Soner Altundo?an, H.

2014-09-01

99

78 FR 64244 - Persulfates From China; Revised Schedule for the Subject Investigation  

Federal Register 2010, 2011, 2012, 2013, 2014

...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Revised Schedule for the Subject Investigation AGENCY: United States International Trade Commission....

2013-10-28

100

78 FR 35314 - Persulfates From China; Notice of Commission Determination To Conduct a Full Five-Year Review  

Federal Register 2010, 2011, 2012, 2013, 2014

...COMMISSION [Investigation No. 731-TA-749 (Third Review)] Persulfates From China; Notice of Commission Determination To Conduct...determine whether revocation of the antidumping duty order on persulfates from China would be likely to lead to continuation or...

2013-06-12

101

Evaluation of persulfate oxidative wet scrubber for removing BTEX gases  

Microsoft Academic Search

Soil vapor extraction (SVE) coupled with air sparging of groundwater is a method commonly used to remediate soil and groundwater contaminated with volatile organic petroleum contaminants such as gasoline. These hazardous contaminants are mainly attributable to the compounds—benzene, toluene, ethylbenzene, and xylenes (known collectively as BTEX). Exhaust gas from SVE may contain BTEX, and therefore must be treated before being

Chenju Liang; Yan-Jyun Chen; Keng-Jung Chang

2009-01-01

102

78 FR 13891 - Persulfates From China; Institution of a Five-Year Review Concerning the Antidumping Duty Order...  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-749 (Third Review)] Persulfates From China; Institution of a Five-Year...Concerning the Antidumping Duty Order on Persulfates From China AGENCY: United States International...revocation of the antidumping duty order on persulfates from China would be likely to lead...

2013-03-01

103

78 FR 40695 - Persulfates From the People's Republic of China: Final Results of Expedited Third Sunset Review...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...review of the antidumping duty order on persulfates from the PRC pursuant to section...

2013-07-08

104

76 FR 28419 - Persulfates From the People's Republic of China: Final Results of the 2009-2010 Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-878] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...FMC''), a domestic producer of persulfates and an interested party in this...

2011-05-17

105

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...incorrect case number associated with persulfates from the PRC (i.e., case...

2011-06-17

106

78 FR 52969 - Persulfates From China; Scheduling of a Full Five-Year Review Concerning the Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-749 (Third Review)] Persulfates From China; Scheduling of a Full Five-Year...Concerning the Antidumping Duty Order on Persulfates from China AGENCY: United States International...revocation of the antidumping duty order on persulfates from China would be likely to lead...

2013-08-27

107

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Trade Administration [A-570-847] Persulfates From the People's Republic of China...review of the antidumping duty order on persulfates from the People's Republic of China...Register the antidumping duty order on persulfates from the PRC.\\1\\ On July 1,...

2011-03-11

108

The control of emerging haloacetamide DBP precursors with UV/persulfate treatment.  

PubMed

Haloacetamides (HAcAms), an emerging class of nitrogen-containing disinfection byproducts (N-DBPs) of health concern in drinking water, have been reported to occur in treated drinking waters at low ?g/L levels typically. The objective of this study was to examine the potential of an ultraviolet light/persulfate (UV/PS) oxidation technology to reduce the precursors of HAcAms and also minimize the formation of other N-DBPs upon subsequent chlorination. Low-pressure UV photolysis alone and PS pre-oxidation alone did not significantly affect HAcAm formation, however UV/PS pre-oxidation achieved a statistically significant reduction in HAcAm formation and also reduced bromine incorporation into the HAcAms. UV/PS also showed a good performance in removing the precursors of haloacetonitriles and halonitromethanes prior to chlorination. Therefore, UV/PS has the potential to minimize the formation of a range of N-DBPs in organic nitrogen-rich waters where N-DBP precursors are prevalent. However, these benefits should be weighed against the potential drawbacks of increased bromate and sulfate formation, particularly in high-bromide waters. PMID:25267364

Chu, Wenhai; Li, Dongmei; Gao, Naiyun; Templeton, Michael R; Tan, Chaoqun; Gao, Yuqiong

2014-09-22

109

Degradation and dechlorination of pentachlorophenol by microwave-activated persulfate.  

PubMed

The degradation performance of pentachlorophenol (PCP) by the microwave-activated persulfate (MW/PS) process was investigated in this study. The results indicated that degradation efficiency of PCP in the MW/PS process followed pseudo-first-order kinetics, and compared with conventional heating, microwave heating has a special effect of increasing the reaction rate and reducing the process time. A higher persulfate concentration and reaction temperature accelerated the PCP degradation rate. Meanwhile, increasing the pH value and ionic strength of the phosphate buffer slowed down the degradation rate. The addition of ethanol and tert-butyl alcohol as hydroxyl radical and sulfate radical scavengers proved that the sulfate radicals were the dominant active species in the MW/PS process. Gas chromatography-mass spectrometry (GC-MS) was employed to identify the intermediate products, and then a plausible degradation pathway involving dechlorination, hydrolysis, and mineralization was proposed. The acute toxicity of PCP, as tested with Photobacterium phosphoreum, Vibrio fischeri, and Vibrio qinghaiensis, was negated quickly during the MW/PS process, which was in agreement with the nearly complete mineralization of PCP. These results showed that the MW/PS process could achieve a high mineralization level in a short time, which provided an efficient way for PCP elimination from wastewater. PMID:25328098

Qi, Chengdu; Liu, Xitao; Zhao, Wei; Lin, Chunye; Ma, Jun; Shi, Wenxiao; Sun, Qu; Xiao, Hao

2015-03-01

110

Heating activated carbon by electromagnetic induction  

Microsoft Academic Search

The purpose of this study is the use of electromagnetic induction to heat activated carbon. The ultimate goal is to get an original process to regenerate adsorbants loaded with the volatile organic compounds present in air or water.The first step was to explore the possibilities of heating granular activated carbon with this technology. In order to get the best operating

P. Mocho; J. Ch. Bourhis; P. Le Cloirec

1996-01-01

111

Degradation of carbon tetrachloride in aqueous solution in the thermally activated persulfate system.  

PubMed

Thermal activation of persulfate (PS) has been identified to be effective in the destruction of organic pollutants. The feasibility of carbon tetrachloride (CT) degradation in the thermally activated PS system was evaluated. The experimental results showed that CT could be readily degraded at 50°C with a PS concentration of 0.5M, and CT degradation and PS consumption followed the pseudo-first order kinetic model. Superoxide radical anion (O2(-)) was the predominant radical species responsible for CT degradation and the split of CCl was proposed as the possible reaction pathways for CT degradation. The process of CT degradation was accelerated by higher PS dose and lower initial CT concentration. No obvious effect of the initial pH on the degradation of CT was observed in the thermally activated PS system. Cl(-), HCO3(-), and humic acid (HA) had negative effects on CT degradation. In addition, the degradation of CT in the thermally activated PS system could be significantly promoted by the solvents addition to the solution. In conclusion, the thermally activated PS process is a promising option in in-situ chemical oxidation/reduction remediation for degrading highly oxidized organic contaminants such as CT that is widely detected in contaminated sites. PMID:25544995

Xu, Minhui; Gu, Xiaogang; Lu, Shuguang; Qiu, Zhaofu; Sui, Qian; Miao, Zhouwei; Zang, Xueke; Wu, Xiaoliang

2015-04-01

112

Degradation of TCE using Persulfate (PS) and Peroxymonosulfate (PMS): Effect of Inorganic Ions in Groundwater  

E-print Network

Abstract — The objective of this study was to investigate the effects of inorganic ions on persulfate (PS) and peroxymonosulfate (PMS) oxidation to degrade trichloroethylene (TCE) in groundwater. First, the groundwater samples, which was taken from Wonju, Korea, were analyzed, and the highest concentration of target ions (Mg 2+, Ca 2+, Fe 2+, Mn 2+, Cl-, HCO 3) in those samples were used for the batch experiment. Based on batch test, all of target ions did not neither increase nor decrease the reactivity of both PS and PMS. Because of the fluctuation of groundwater compositions, it could be worthwhile to evaluate which ions increase or decrease the reactivity of oxidants. Therefore, a batch system with an excess of target ion was tested. The results showed that ferrous ion increased the reactivity of both PS and PMS. However, chloride ion increased the reactivity of PMS, but it inhibited the reactivity of PS. Moreover, residual concentration of PMS and PS were remained approximately 97~98%, and the pH of system was dramatically reduced when PMS was used. The last of target ions (Mg 2+, Ca 2+, Mn 2+, HCO 3) will be also tested with the condition of an excess.

Ki-man Park; Hong-kyun Lee; Si-hyun Do; Sung-ho Kong

113

Silver-catalyzed PuO sub 2 dissolution with persulfate  

SciTech Connect

This report consists of 14 slides and associated narrative for a presentation to be given at the 15th Annual Actinide Separations Conference on silver-catalyzed PuO{sub 2} dissolution with persulfate. (JL)

Fisher, F D; Barney, G S; Cooper, T D; Duchsherer, M J

1991-06-01

114

Bidentate Dicarboxylate Capping Groups and Photosensitizers Control the Size of IrO2 Nanoparticle Catalysts for Water Oxidation  

E-print Network

are good catalysts for water photo-oxidation in persulfate/sensitizer solutions. Ruthenium tris(2(IV). In 1 M persulfate solutions in pH 5.8 Na2SiF6/NaHCO3 buffer solutions, the excited- state of the bound

115

Disinfection of ballast water with iron activated persulfate.  

PubMed

The treatment of ballast water carried onboard ships is critical to reduce the spread of nonindigenous aquatic organisms that potentially include noxious and harmful taxa. We tested the efficacy of persulfate (peroxydisulfate, S2O8(2-), PS) activated with zerovalent iron (Fe(0)) as a chemical biocide against two taxa of marine phytoplankton grown in bench-scale, batch cultures: the diatom, Pseudonitzshia delicatissima and the green alga, Dunaliella tertiolecta . After testing a range of PS concentrations (0-4 mM activated PS) and exposure times (1-7 days), we determined that a dosage of 4 mM of activated PS was required to inactivate cells from both species, as indicated by reduced or halted growth and a reduction in photosynthetic performance. Longer exposure times were required to fully inactivate D. tertiolecta (7 days) compared to P. delicatissima (5 days). Under these conditions, no recovery was observed upon placing cells from the exposed cultures into fresh media lacking biocide. The results demonstrate that activated PS is an effective chemical biocide against species of marine phytoplankton. The lack of harmful byproducts produced during application makes PS an attractive alternative to other biocides currently in use for ballast water treatments and merits further testing at a larger scale. PMID:24024829

Ahn, Samyoung; Peterson, Tawnya D; Righter, Jason; Miles, Danielle M; Tratnyek, Paul G

2013-10-15

116

Synthesis of per-sulfated flavonoids using 2,2,2-trichloro ethyl protecting group and their factor Xa inhibition potential  

E-print Network

Synthesis of per-sulfated flavonoids using 2,2,2-trichloro ethyl protecting group and their factor November 2004; accepted 30 November 2004 Available online 28 December 2004 Abstract--The synthesis of per-sulfated as a protecting group. The two-step synthesis results in exclusive formation of the per-sulfated product

Desai, Umesh R

117

Is it possible to remediate a BTEX contaminated chalky aquifer by in situ chemical oxidation?  

PubMed

An industrial coating site in activity located on a chalky plateau, contaminated by BTEX (mainly xylenes, no benzene), is currently remediated by in situ chemical oxidation (ISCO). We present the bench scale study that was conducted to select the most appropriate oxidant. Ozone and catalyzed hydrogen peroxide (Fenton's reaction) were discarded since they were incompatible with plant activity. Permanganate, activated percarbonate and activated persulfate were tested. Batch experiments were run with groundwater and groundwater-chalk slurries with these three oxidants. Total BTEX degradation in groundwater was reached with all the oxidants. The molar ratios [oxidant]:[Fe(2+)]:[BTEX] were 100:0:1 with permanganate, 100:100:1 with persulfate and 25:100:1 with percarbonate. Precipitation of either manganese dioxide or iron carbonate (siderite) occurred. The best results with chalk slurries were obtained with permanganate at the molar ratio 110:0:1 and activated persulfate at the molar ratio 110:110:1. To avoid precipitation, persulfate was also used without activation at the molar ratio 140:1. Natural Oxidant Demand measured with both oxidants was lower than 5% of initial oxidant contents. Activated percarbonate was not appropriate because of radical scavenging by carbonated media. Permanganate and persulfate were both effective at oxidant concentrations of ca 1 g kg(-1) with permanganate and 1.8 g kg(-1) with persulfate and adapted to site conditions. Activation of persulfate was not mandatory. This bench scale study proved that ISCO remediation of a chalky aquifer contaminated by mainly xylenes was possible with permanganate and activated or unactivated persulfate. PMID:21733544

Lemaire, Julien; Croze, Véronique; Maier, Joachim; Simonnot, Marie-Odile

2011-08-01

118

On the Efect of the Oxidative Reagents on the Conductivity of Polyaniline/MMT Nanocomposites  

NASA Astrophysics Data System (ADS)

The synthesis of polyaniline has been reported using three different oxidative reagents: ammonium persulfate, potassium iodate and potassium iodate+sodium hypochlorite. This polyaniline has been used to prepare several nanocomposites with different percentage of Montmorillonite. The DC conductivity of the nanocomposites was determined by impedance spectroscopy. The oxidative reagent that gives higher conductivity is ammonium persulfate. The temperature dependence of the conductivity was studied.

Garcia-Bernabé, A.; Gil-Agustí, M.; Ortega, G.; Llovera, P.; Almarza, A.; Vázquez, S.; Amantia, D.; Aubouy, L.

2010-06-01

119

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

PubMed

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. PMID:25459832

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

2014-10-25

120

Tight gas sands research program: Field operations and analysis. Degradation of hydroxypropyl guar fracturing fluids by enzyme, oxidative, and catalyzed oxidative breakers. Part 1. Linear hydroxypropyl guar solutions. Topical report, February 1991-December 1991  

SciTech Connect

The research was designed to accomplish the following objectives: Determine the effects of pH, temperature, and polymer concentration on HPG solution degradation by enzyme, oxidative (ammonium persulfate), and catalyzed oxidative breakers (ammonium persulfate with triethanolamine); Identify the appropriate breaker system for HPG solutions in the temperature range of 120 deg F - 140 deg F; and Determine the temperature range for HPG solutions where chemical breakers are not necessary to degrade the fluid.

Craig, D.; Holditch, S.A.

1993-12-01

121

Oxidation of Aromatic Aldehydes Using Oxone  

ERIC Educational Resources Information Center

The experiment demonstrating the feasibility of using water as a solvent for organic reactions which highlights the cost and environmental benefits of its use is presented. The experiment encourages students to think in terms of the reaction mechanism of the oxidation of aldehydes knowing that potassium persulfate is the active oxidant in Oxone…

Gandhari, Rajani; Maddukuri, Padma P.; Thottumkara, Vinod K.

2007-01-01

122

Heat-activated cooling devices: A guidebook for general audiences  

SciTech Connect

Heat-activated cooling is refrigeration or air conditioning driven by heat instead of electricity. A mill or processing facility can us its waste fuel to air condition its offices or plant; using waste fuel in this way can save money. The four basic types of heat-activated cooling systems available today are absorption cycle, desiccant system, steam jet ejector, and steam turbine drive. Each is discussed, along with cool storage and biomass boilers. Steps in determining the feasibility of heat-activated cooling are discussed, as are biomass conversion, system cost and integration, permits, and contractor selection. Case studies are given.

Wiltsee, G.

1994-02-01

123

The synthesized and thermally modified Mn-Ca-FeOOH composite in persulfate system: Its role to discolor methylene blue  

NASA Astrophysics Data System (ADS)

Methylene blue (MB) discoloration was performed using persulfate (PS) activated with the synthesized composites. Four types of composites, which were synthesized by the immobilization of Mn on iron oxides (hematite and goethite) using either NaOH or Ca(OH)2, were evaluated as PS activator. The synthesized Mn-Ca-FeOOH composite was selected and it was thermally modified at 300 and 700 °C (denoted Mn-Ca-FeOOH_300 and Mn-Ca-FeOOH_700). The BET surface area of Mn-Ca-FeOOH_300 was similar to that of Mn-Ca-FeOOH while that of Mn-Ca-FeOOH_700 was dramatically lower. XRD and XPS analysis indicated that the thermal modification transformed iron oxides from goethite to hematite and changed amorphous manganese oxide to crystalline. MB discoloration at pH 3 indicated that Mn-Ca-FeOOH acted as an oxidant to degrade MB, and the thermally modified composites (i.e. Mn-Ca-FeOOH_300 and Mn-Ca-FeOOH_700) acted as a catalyst to activate PS. Moreover, incomplete MB discoloration was observed in PS/composite system at pH 3. However, a whole tested wavelength of MB was reduced when MB discoloration was tested in PS/composite system above pH 7. Moreover, the increasing pH of solution increased MB discoloration. The higher MB discoloration in heterogeneous system at pH 12 could suggest that superoxide anion (O2•-) was dominant reactive oxygen species.

Jo, Young-Hoon; Hong, Seong-Ho; Park, Tae-Jin; Do, Si-Hyun

2014-05-01

124

Nitroxide mediated living radical polymerization of styrene in miniemulsion—modelling persulfate-initiated systems  

Microsoft Academic Search

Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion polymerization (NMMP) of styrene at 135°C, using alkoxyamine initiators to control polymer growth (Nitroxide-Mediated Polymerization of Styrene in Miniemulsion. Modeling Studies of Alkoxyamine-Initiated Systems, 2001b). The model has since been expanded to describe styrene NMMP at 135°C using TEMPO and the free radical initiator, potassium persulfate (KPS). The

John W. Ma; Michael F. Cunningham; Kim B. McAuley; Barkev Keoshkerian; Michael Georges

2003-01-01

125

Paramagnetic centers in products of the mechanical treatment of potassium persulfate  

SciTech Connect

It was shown that the mechanical breakdown of potassium persulfate at 77/sup 0/K is accompanied by the formation of paramagnetic centers of the types of SO/sub 4//sup -/, SO/sub 5//sup -/, and radical pairs. It was established that heating a mechanically activated sample to 375/sup 0/K leads to an increase in the concentration of paramagnetic centers by more than an order of magnitude. This process is due to breakdown of the (S/sub 2/O/sub 8/)/sup 2 -/ anions and randomization of the structure of the persulfate as a result of mechanical influences. The effects of randomization of the structure of the solid are also manifested in the changes in the form of the ESR spectra of the paramagnetic centers and the increase in the rate of the chemical conversions of the radicals. The direction of the reactions of paramagnetic centers of different structures in potassium persulfate was established, and a radical-chain scheme of thermal decomposition of the substance was proposed on this basis.

Radstig, V.A.; Politov, A.A.

1985-07-01

126

Reduction of diffusive contaminant emissions from a dissolved source in a lower permeability layer by sodium persulfate treatment.  

PubMed

Residual contamination contained in lower permeability zones is difficult to remediate and can, through diffusive emissions to adjacent higher permeability zones, result in long-term impacts to groundwater. This work investigated the effectiveness of oxidant delivery for reducing diffusive emissions from lower permeability zones. The experiment was conducted in a 1.2 m tall × 1.2 m wide × 6 cm thick tank containing two soil layers having 3 orders of magnitude contrast in hydraulic conductivity. The lower permeability layer initially contained dissolved methyl tert-butyl ether (MTBE) and benzene, toluene, ethylbenzene, and p-xylenes (BTEX). The treatment involved delivery of 10% w/w nonactivated sodium persulfate (Na2S2O8) solution to the high permeability layer for 14 days. The subsequent diffusion into the lower permeability layer and contaminant emission response were monitored for about 240 days. The S2O8(2-) diffused about 14 cm at 1% w/w into the lower permeability layer during the 14 day delivery and continued diffusing deeper into the layer as well as back toward the higher-lower permeability interface after delivery ceased. Over 209 days, the S2O8(2-) diffused 60 cm into the lower permeability layer, the BTEX mass and emission rate were reduced by 95-99%, and the MTBE emission rate was reduced by 63%. The overall treatment efficiency was about 60-110 g-S2O8(2-)delivered/g-hydrocarbon oxidized, with a significant fraction of the oxidant delivered likely lost by back-diffusion and not involved in hydrocarbon destruction. PMID:25386986

Cavanagh, Bridget A; Johnson, Paul C; Daniels, Eric J

2014-12-16

127

Plutonium oxide dissolution  

SciTech Connect

Several processing options for dissolving plutonium oxide (PuO{sub 2}) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO{sub 2} typically generated by burning plutonium metal and PuO{sub 2} produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO{sub 2} in canyon dissolvers. The options involve solid solution formation of PuO{sub 2} With uranium oxide (UO{sub 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{sub 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{sub 2} materials may warrant further study.

Gray, J.H.

1992-09-30

128

Plutonium oxide dissolution  

SciTech Connect

Several processing options for dissolving plutonium oxide (PuO[sub 2]) from high-fired materials have been studied. The scoping studies performed on these options were focused on PuO[sub 2] typically generated by burning plutonium metal and PuO[sub 2] produced during incineration of alpha contaminated waste. At least two processing options remain applicable for dissolving high-fired PuO[sub 2] in canyon dissolvers. The options involve solid solution formation of PuO[sub 2] With uranium oxide (UO[sub 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[sub 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[sub 2] materials may warrant further study.

Gray, J.H.

1992-09-30

129

PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP  

E-print Network

PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP W. D. C. Richards and W. L. Auxer) which employs a natural gas fired Stirling engine to drive a Rankine cycle vapor compressor is presently by the heat pump effect. The Stirling engine/Rankine cycle refrigeration loop heat pump being developed would

Oak Ridge National Laboratory

130

Removal of 2-MIB and geosmin using UV/persulfate: contributions of hydroxyl and sulfate radicals.  

PubMed

2-methylisoborneol (2-MIB) and geosmin are two odor-causing compounds that are difficult to remove and the cause of many consumer complaints. In this study, we assessed the degradation of 2-MIB and geosmin using a UV/persulfate process for the first time. The results showed that both 2-MIB and geosmin could be degraded effectively using this process. The process was modeled based on steady-state assumption with respect to the odor-causing compounds and either hydroxyl or sulfate radicals. The second order rate constants for 2-MIB and geosmin reacting with the sulfate radical (SO4(-)) were estimated to be (4.2 ± 0.6) × 10(8) M(-1)s(-1) and (7.6 ± 0.6) × 10(8) M(-1)s(-1) respectively at a pH of 7.0. The contributions of the hydroxyl radical (OH) to 2-MIB and geosmin degradation were 3.5 times and 2.0 times higher, respectively, than the contribution from SO4(-) in Milli-Q water with 2 mM phosphate buffer at pH 7.0. The pseudo-first-order rate constants (ko(s)) of both 2-MIB and geosmin increased with increasing dosages of persulfate. Although pH did not affect the degradation of 2-MIB and geosmin directly, different scavenging effects of hydrogen phosphate and dihydrogen phosphate resulted in higher values of ko(s) for both 2-MIB and geosmin in acidic condition. Bicarbonate and natural organic matter (NOM) inhibited the degradation of both 2-MIB and geosmin dramatically through consuming OH and SO4(-) and were likely to be the main radical scavengers in natural waters when using UV/persulfate process to control 2-MIB and geosmin. PMID:25486622

Xie, Pengchao; Ma, Jun; Liu, Wei; Zou, Jing; Yue, Siyang; Li, Xuchun; Wiesner, Mark R; Fang, Jingyun

2015-02-01

131

Removal of elemental mercury from flue gas by thermally activated ammonium persulfate in a bubble column reactor.  

PubMed

In this article, a novel technique on removal of elemental mercury (Hg(0)) from flue gas by thermally activated ammonium persulfate ((NH4)(2)S(2)O(8)) has been developed for the first time. Some experiments were carried out in a bubble column reactor to evaluate the effects of process parameters on Hg(0) removal. The mechanism and kinetics of Hg(0) removal are also studied. The results show that the parameters, (NH4)(2)S(2)O(8) concentration, activation temperature and solution pH, have significant impacts on Hg(0) removal. The parameters, Hg(0), SO2 and NO concentration, only have small effects on Hg(0) removal. Hg(0) is removed by oxidations of (NH4)(2)S(2)O(8), sulfate and hydroxyl free radicals. When (NH4)(2)S(2)O(8) concentration is more than 0.1 mol/L and solution pH is lower than 9.71, Hg(0) removal by thermally activated (NH4)(2)S(2)O(8) meets a pseudo-first-order fast reaction with respect to Hg(0). However, when (NH4)(2)S(2)O(8) concentration is less than 0.1 mol/L or solution pH is higher than 9.71, the removal process meets a moderate speed reaction with respect to Hg(0). The above results indicate that this technique is a feasible method for emission control of Hg(0) from flue gas. PMID:25251199

Liu, Yangxian; Wang, Qian

2014-10-21

132

Study on the polarographic catalytic wave of vitamin P in the presence of persulfate and its application.  

PubMed

The polarographic catalytic wave of vitamin P in the presence of persulfate was studied by linear potential scan polarography and cyclic voltammetry. Vitamin P yielded a single reduction wave in acidic aqueous solution, which was ascribed to a 2e(-), 2H(+) reduction of the carbonyl group in the C-4 position. Actually, the carbonyl group C=O first underwent a 1e(-), 1H(+) reduction to form a neutral free radical, and the further 1e(-), 1H(+) reduction of the free radical was simultaneous with its following chemical reactions. When S(2)O(2-)(8) was present, the free radical of vitamin P was oxidized by both S(2)O(2-)(8) and its reduction intermediate, the sulfate radical anion SO(*-)(4), to regenerate the original, which resulted in the production of a polarographic catalytic wave of vitamin P. Based on this catalytic wave, a novel method for the determination of vitamin P was proposed. In 0.02 M tartaric acid-sodium tartrate (pH 3.3) buffer containing 5.0 x 10(-3) M K(2)S(2)O(8), the peak potential of the catalytic wave was -1.42 V (vs SCE) and the peak current was rectilinear to the vitamin P concentration in the range of 8.0 x 10(-9)-1.0 x 10(-6) M (r = 0.9994, n = 13). The catalytic wave of 2.0 x 10(-7) M vitamin P enhanced the polarographic current 70 times compared with the corresponding reduction wave. The detection limit was 2.0 x 10(-9) M, and the relative standard deviation at the 2.0 x 10(-7) M level was 0.7% (n = 15). The proposed method was used for the determination of vitamin P content in the pharmaceutical preparation of tablets and the medicinal plant Sophora japonica L. without previous separation. PMID:12009698

Song, Jun Feng; He, Ping; Guo, Wei

2002-05-15

133

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

PubMed

The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S?O?(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?O?(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?O?(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?O?(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. PMID:23747463

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

2013-09-15

134

Heat-activated liposome targeting to streptavidin-coated surfaces.  

PubMed

There is a great need of improved anticancer drugs and corresponding drug carriers. In particular, liposomal drug carriers with heat-activated release and targeting functions are being developed for combined hyperthermia and chemotherapy treatments of tumors. The aim of this study is to demonstrate the heat-activation of liposome targeting to biotinylated surfaces, in model experiments where streptavidin is used as a pretargeting protein. The design of the heat-activated liposomes is based on liposomes assembled in an asymmetric structure and with a defined phase transition temperature. Asymmetry between the inside and the outside of the liposome membrane was generated through the enzymatic action of phospholipase D, where lipid head groups in the outer membrane leaflet, i.e. exposed to the enzyme, were hydrolyzed. The enzymatically treated and purified liposomes did not bind to streptavidin-modified surfaces. When activation heat was applied, starting from 22°C, binding of the liposomes occurred once the temperature approached 33±0.5°C. Moreover, it was observed that the asymmetric structure remained stable for at least 2weeks. These results show the potential of asymmetric liposomes for the targeted binding to cell membranes in response to (external) temperature stimulus. By using pretargeting proteins, this approach can be further developed for personalized medicine, where tumor-specific antibodies can be selected for the conjugation of pretargeting agents. PMID:25732026

Jing, Yujia; Trefná, Hana Dobší?ek; Persson, Mikael; Svedhem, Sofia

2015-06-01

135

In situ oxidation of petroleum-hydrocarbon contaminated groundwater using passive ISCO system.  

PubMed

Groundwater contamination by gasoline spill is a worldwide environmental problem. Gasoline contains methyl tertiary-butyl ether (MTBE) (a fuel oxygenates) and benzene, which are the chemicals of concerns among the gasoline components. In this study, an in situ chemical oxidation (ISCO) barrier system was developed to evaluate the feasibility of applying this passive system on the control of MTBE and benzene plume in aquifer. The developed ISCO barrier contained oxidant-releasing materials, which could release oxidants (e.g., persulfate) when contact with water for the contaminants' oxidation in groundwater. In this study, laboratory-scale fill-and-draw experiments were conducted to determine the component ratios of the oxidant-releasing materials and evaluate the persulfate release rates. Results indicate that the average persulfate-releasing rate of 7.26 mg S(2)O(8)(2-)/d/g was obtained when the mass ratio of sodium persulfate/cement/sand/water was 1/1.4/0.24/0.7. The column study was conducted to evaluate the efficiency of in situ application of the developed ISCO barrier system on MTBE and benzene oxidation. Results from the column study indicate that approximately 86-92% of MTBE and 95-99% of benzene could be removed during the early persulfate-releasing stage (before 48 pore volumes of groundwater pumping). The removal efficiencies for MTBE and benzene dropped to approximately 40-56% and 85-93%, respectively, during the latter part of the releasing period due to the decreased persulfate-releasing rate. Results reveal that acetone, byproduct of MTBE, was observed and then further oxidized completely. Results suggest that the addition of ferrous ion would activate the persulfate oxidation. However, excess ferrous ion would compete with organic contaminants for persulfate, and thus, cause the decrease in contaminant oxidation rates. The proposed treatment scheme would be expected to provide a more cost-effective alternative to remediate MTBE, benzene, and other petroleum-hydrocarbon contaminated aquifers. Results from this study will be useful in designing a scale-up system for field application. PMID:21396673

Liang, S H; Kao, C M; Kuo, Y C; Chen, K F; Yang, B M

2011-04-01

136

Determination of dissolved organic nitrogen using persulfate oxidation and conductimetric quantification of nitrate?nitrogen  

Microsoft Academic Search

Nitrogen (N) in forest soil extracts and surface waters may be dominantly in organic compounds as dissolved organic nitrogen (DON). Due to various difficulties associated with measuring total N (as TKN) by the Rjeldahl digest, this important vehicle for nutrient movement is rarely monitored. By coupling two relatively new methods and optimizing them for use in soil studies, we developed

Z. S. Yu; R. R. Northup; R. A. Dahlgren

1994-01-01

137

Water-soluble organic nitrogen in atmospheric aerosol: a comparison of UV and persulfate oxidation methods  

Microsoft Academic Search

Two well established methods that are widely applied in the determination of marine dissolved organic nitrogen (DON) have been investigated in their application to the determination of rainwater DON and the water-soluble organic nitrogen component of atmospheric aerosol. Empirical observation highlighted some difficulties in the analysis of DON in these non-marine matrices, so some practical suggestions for the extension of

S. E Cornell; T. D Jickells

1999-01-01

138

Diffusion and polymerization of styrene in an aqueous solution of potassium persulfate under static conditions  

SciTech Connect

The potassium persulfate-initiated polymerization of styrene in a mechanically agitated mixture of water and monomer leads to the formation of a stable, monodisperse latex. In order to explain the mechanism of the stabilization of the latex particles in this system, the authors present a detailed investigation of the polymerization of styrene in a specially constructed electrochemical cell under static conditions. A schematic of the cell is shown. Results show that the capacity of the electrical double layer on the platinum electrode remains constant with time in a system containing only a solution of electrolyte, either K/sub 2/SO/sub 4/ or K/sub 2/S/sub 2/O/sub 8/.

Oganesyan, A.A.; Boyadzhyan, V.G.; Gritskova, I.A.; Gukasyan, A.V.; Matsoyan, S.G.; Pravednikov, A.N.

1985-10-01

139

Persistence of Asthmatic Response after Ammonium Persulfate-Induced Occupational Asthma in Mice  

PubMed Central

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. PMID:25303285

Ollé-Monge, Marta; Muñoz, Xavier; Vanoirbeek, Jeroen A. J.; Gómez-Ollés, Susana; Morell, Ferran; Cruz, María-Jesus

2014-01-01

140

Photocatalytic water oxidation by Nafion-stabilized iridium oxide colloids Michikazu Hara and Thomas E. Mallouk*  

E-print Network

Photocatalytic water oxidation by Nafion-stabilized iridium oxide colloids Michikazu Hara IrO2·xH2O stabilized by soluble Nafion, tris(2,2A-bipyridyl)ruthenium(II), and persulfate efficiently conventional catalysts. In this paper, we report O2 evolution from a [Ru(bpy)3]2+­Nafion- stabilized IrO2·xH2O

141

Solution polymerization of acrylamide using potassium persulfate as an initiator: kinetic studies, temperature and pH dependence  

Microsoft Academic Search

The kinetics of the radical polymerization of acrylamide in aqueous solution using potassium persulfate as initiator has been investigated by the gravimetric technique. Up to 94% conversion was obtained. The rate of polymerization was governed by the expression at 55°CRpo=k[K2S2O8]0.5[M]01.26The order with respect to initiator was consistent with the classical kinetic rate equation, while the order with respect to monomer

Hong-Ru Lin

2001-01-01

142

Investigation of the toxicity of common oxidants used in advanced oxidation processes and their quenching agents.  

PubMed

The inhibitory effect of commonly known oxidants and their quenching agents was investigated by employing a battery of toxicity tests. Hydrogen peroxide toxicity could be effectively eliminated by the enzyme catalase, whereas sodium thiosulfate and ascorbic acid were recommended as suitable quenching agents for the removal of the oxidants persulfate and peroxymonosulfate in the Vibrio fischeri bioassays. None of the studied quenching agents was found to be suitable for persulfate and peroxymonosulfate in the Daphnia magna bioassays since high inhibitory effects were obtained for both oxidants. In the case of Pseudokirchneriella subcapitata, manganese dioxide powder should be used as an alternative quenching agent to catalase, since this enzyme exhibited a highly toxic effect towards these microalgae. Sodium sulfite, which is extensively used as a quenching agent, was not appropriate for quenching peroxymonosulfate in all studied bioassays. PMID:24996151

Olmez-Hanci, Tugba; Arslan-Alaton, Idil; Dursun, Duygu

2014-08-15

143

Photocatalytic synthesis of dihydrobenzofurans by oxidative [3+2] cycloaddition of phenols.  

PubMed

We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible-light-activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled, benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations. PMID:25155300

Blum, Travis R; Zhu, Ye; Nordeen, Sarah A; Yoon, Tehshik P

2014-10-01

144

Polarographic determination of diazepam with its parallel catalytic wave in the presence of persulfate.  

PubMed

A new method for the determination of diazepam was proposed based on its polarographic catalytic wave in the presence of persulfate. In 0.20 M NaAc-HAc (pH 4.7)-1.0 x 10(-2) M K(2)S(2)O(8) supporting electrolyte, the reduction wave of diazepam with peak potential -0.89 V (versus SCE) was catalyzed, producing a parallel catalytic wave. The peak current of the catalytic wave was 15 times higher than that of the corresponding reduction wave for 4.0 x 10(-6) M diazepam, and was rectilinear to diazepam concentration in the range of 5.6 x 10(-8) to 8.9 x 10(-6) and 8.8 x 10(-6) to 2.0 x 10(-4) M. The detection limit was 9.6 x 10(-9) M. The mechanism of the parallel catalytic wave of diazepam was discussed. PMID:15019049

Guo, Wei; Lin, Hong; Liu, Limin; Song, Junfeng

2004-03-10

145

In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies  

NASA Technical Reports Server (NTRS)

This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

Keith, Amy; Glasgow, Jason; McCaleh, Rececca C. (Technical Monitor)

2001-01-01

146

Chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soils.  

PubMed

Chemical oxidation of hexachlorocyclohexanes (HCHs) was evaluated in (i) artificially spiked sand with HCH isomers (?, ?, ? and ?) and (ii) contaminated soil sampled from a former gravel pit backfilled with wastes of lindane (?-HCH). Following oxidation treatments were employed: hydrogen peroxide alone (HP), hydrogen peroxide with soluble Fe(II) (Fenton-F), sodium persulfate alone (PS), Fe(II) activated persulfate (AP) and permanganate (PM). GC-MS results revealed a significant degradation of all isomers in spiked soil in the order: F>PS>AP>HP>PM. Soluble Fe(II) enhanced the efficiency of H2O2 but decreased the reactivity of persulfate. Similar trend was observed in contaminated soil, but with less degradation probably caused by scavenging effect of organic matter and soil minerals and/or pollutant unavailability. No significant increase in oxidation efficiency was observed after using availability-enhancement agents in contaminated soil. Other limitation factors (oxidant dose, pH, catalyst type etc.) were also addressed. Among all the isomers tested, ?-HCH was the most recalcitrant one which could be explained by higher metabolic and chemical stability. No by-products were observed by GC-MS regardless of the oxidant used. For being the premier study reporting chemical oxidation of HCH isomers in contaminated soils, it will serve as a base for in-situ treatments of sites contaminated by HCH isomers and other persistent organic pollutants. PMID:24486498

Usman, M; Tascone, O; Faure, P; Hanna, K

2014-04-01

147

[Influences of pH and complexing agents on degradation of reactive brilliant blue KN-R by ferrous activated persulfate].  

PubMed

The influences of pH and complexing agents on degradation of reactive brilliant blue KN-R by ferrous activated persulfate were investigated, and finally the complexed and the uncomplexed system were compared. Because the lower the pH the more quickly will be the dissociation of S2O8(2-) to the SO4(-*) and the ORP of the dominant radical SO4(-*) in the acidic condition is higher than the dominant radical *OH in the alkaline condition, KN-R degradation rates in acidic condition are far outweigh in the neutral and alkaline conditions. When pH value was 3, the residual rate of KN-R was 17.0% within 3 hours by EDTA system with the lowest PS consumption rate 32.3%, so EDTA was the best complexing agent choice in acidic condition. When pH value was 7, the residual rates of KN-R were 11.3%, 12.4% within 3 days by EDTA, citric acid system with the PS residual rates 28.9%, 28.0% respectively, so EDTA, citric acid were the better choices in the neutral condition. When pH value was 10, glucose acid, citric acid, EDTA and tartaric acid systems all had the similar KN-R degradation rates and PS residual rates, so all could acted as the complexing agents, when the system contained trace amounts of ferrous, the addition of complexing agent would greatly improve the degradation rate of pollutant, from original 52.5% to 79.3% of 3 d, so PS is suitable for in situ chemical oxidation (ISCO). PMID:22624381

Zhang, Cheng; Wan, Jin-Quan; Ma, Yong-Wen; Wang, Yan; Huang, Ming-Zhi; Lan, Ming

2012-03-01

148

Oxidation of trace amounts of transplutonium elements to the tetravalent state in solutions of mineral acids and their stabilities  

SciTech Connect

The behavior of trace amounts of americium(IV) in sulfuric and nitric acid solutions as a function of the mineral acid, potassium phosphotungstate, and ammonium persulfate concentrations was investigated. The stability of americium(IV) was studied. The optimal conditions and time of oxidation of trace amounts of americium to the tetravalent state were found on the basis of the experimental data obtained.

Milyukova, M.S.; Varezhkina, N.S.; Kuzovkina, E.V.; Malikov, D.A.; Myasoedov, B.F.

1989-01-01

149

Oxygen-18 study of the mechanism of promoter action of thiocyanate ions in the electrosynthesis of persulfuric acid and ammonium persulfate at platinum anodes  

SciTech Connect

The authors use labelled oxygen to study the involvement of water and sulfate ions in molecular oxygen evolution during the anodic synthesis of persulfuric acid and ammonium persulfate at a platinum anode in an electrolytic cell with and without thiocyanate as a promoter for the electrocatalytic reaction.

Kasatkin, E.V.; Larchenko, L.I.; Potapova, G.F.

1987-02-01

150

Groundwater Sampling at ISCO Sites: Binary Mixtures of Volatile Organic Compounds and Persulfate  

EPA Science Inventory

In-situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming ground-water contaminants into less harmful byproducts. Due to oxidant persistence, ground water samples collected at hazardous waste sites may contain o...

151

Microbial dynamics during and after in situ chemical oxidation of chlorinated solvents.  

PubMed

In situ chemical oxidation (ISCO) followed by a bioremediation step is increasingly being considered as an effective biphasic technology. Information on the impact of chemical oxidants on organohalide respiring bacteria (OHRB), however, is largely lacking. Therefore, we used quantitative PCR (qPCR) to monitor the abundance of OHRB (Dehalococcoides mccartyi, Dehalobacter, Geobacter, and Desulfitobacterium) and reductive dehalogenase genes (rdh; tceA, vcrA, and bvcA) at a field location contaminated with chlorinated solvents prior to and following treatment with sodium persulfate. Natural attenuation of the contaminants tetrachloroethene (PCE) and trichloroethene (TCE) observed prior to ISCO was confirmed by the distribution of OHRB and rdh genes. In wells impacted by persulfate treatment, a 1 to 3 order of magnitude reduction in the abundances of OHRB and complete absence of rdh genes was observed 21 days after ISCO. Groundwater acidification (pH<3) and increase in the oxidation reduction potential (>500 mV) due to persulfate treatment were significant and contributed to disruption of the microbial community. In wells only mildly impacted by persulfate, a slight stimulation of the microbial community was observed, with more than 1 order of magnitude increase in the abundance of Geobacter and Desulfitobacterium 36 days after ISCO. After six months, regeneration of the OHRB community occurred, however, neither D. mccartyi nor any rdh genes were observed, indicating extended disruption of biological natural attenuation (NA) capacity following persulfate treatment. For full restoration of biological NA activity, additional time may prove sufficient; otherwise addition electron donor amendment or bioaugmentation may be required. PMID:24898385

Sutton, Nora B; Atashgahi, Siavash; van der Wal, Jurgen; Wijn, Geert; Grotenhuis, Tim; Smidt, Hauke; Rijnaarts, Huub H M

2015-03-01

152

Adiabatic polymerization of acrylamide in water under the effect of the potassium persulfate-sodium metabisulfite-copper sulfate system  

SciTech Connect

Since adiabatic polymerization of acrylamide (AA) has been studied very little and the information on the effect of copper ions on polymerization of AA prepared in dilute aqueous solutions is very limited, the features of adiabatic polymerization of AA in concentrated aqueous solutions in the presence of the potassium persulfate-sodium metabisulfite-copper sulfate redox initiating system were investigated in this study. The empirical equation for the overall rate of adiabatic polymerization of acrylamide in concentrated aqueous solutions was found, and the effective total activation energy, which decreases with an increase in the concentration of CuSO/sub 4/, was determined. An increase in the molecular weight of the polymer with an increase in the concentration of the monomer and a decrease in the concentration of the components of the initiating system was demonstrated.

Kurenkov, V.F.; Baiburdov, T.A.; Stupen'kova, L.L.

1988-04-10

153

Simultaneous determination of total nitrogen and total phosphorus in environmental waters using alkaline persulfate digestion and ion chromatography.  

PubMed

An ion chromatography (IC) method was developed for the simultaneous determination of total nitrogen and total phosphorus after alkaline persulfate digestion. This study takes advantage of advances in construction of high-resolution, high-capacity anion-exchange columns that can better tolerate the matrices typically encountered when a determination of total nitrogen and total phosphorous is required. Here, we used an electrolytically generated hydroxide eluent combined with a high-capacity, hydroxide-selective, anion-exchange column for the determination of total nitrogen (as nitrate-N) and total phosphorus (as phosphate-P) in environmental samples by IC. This method yielded LODs for nitrate-N and phosphate-P of 1.0 and 1.3 ?g/L, respectively. The LOQs determined for these analytes were 3.4 and 4.2 ?g/L, respectively. Due to the dilution factor required and the blank nitrate-N concentration after the persulfate digestion, the quantification limits increased for nitrate-N and phosphate-P to 171 and 63 ?g/L, respectively. The suitability of the method was evaluated by determining the nitrogen and phosphorus concentrations from known concentrations of organic-containing nitrogen and phosphorus compounds. In addition, environmental samples consisting of six different wastewaters and 48 reservoir samples were evaluated for total nitrogen and phosphorus. The recoveries of nitrogen and phosphorus from the organic-containing compounds ranged from 93.1 to 100.1% and 85.2 to 97.1%, respectively. In addition, good correlation between results obtained by the colorimetric method and IC was also observed. The linearity, accuracy, and evaluation of potential interferences for determining TN and TP will be discussed. PMID:25441080

De Borba, Brian M; Jack, Richard F; Rohrer, Jeffrey S; Wirt, Joan; Wang, Dongmei

2014-11-21

154

40 CFR 141.131 - Analytical requirements.  

Code of Federal Regulations, 2010 CFR

...Persulfate-Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method...Persulfate-Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method...or 5910 B-00 (Ultraviolet Absorption Method) or EPA...

2010-07-01

155

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

PubMed

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. PMID:24450862

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

156

ERDC/ELTR-11-3 Innovative Technology Advocate Formerly Used Defense Sites  

E-print Network

to investigate the use of persulfate to treat PCBs in solution. Heat-activated (50°C) sodium persulfate (Na2S2O8) removed >90% of the PCBs (Aroclor 1254), but lime-activated persulfate was ineffective. A final study of the subject Alaska soils. Some promise might be found for heat-activated persulfate treatment, although

US Army Corps of Engineers

157

Adsorption of chromium(VI) and nickel(II) ions on acid- and heat-activated deoiled spent bleaching clay  

Microsoft Academic Search

De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone\\u000a at temperatures between 200 and 800C. The surface area of the heat-activated clay attained a maximal value of ?120 m2 g?1 at temperatures between 400 and 500C while the acid-heat-treated clay attained maximal surface area of ?140 m2 g?1. The adsorption

C. E. Seng; C. G. Lee; K. Y. Liew

2001-01-01

158

Styrene\\/potassium persulfate\\/water systems: effects of hydrophilic comonomers and solvent additives on the nucleation mechanism and the particle size  

Microsoft Academic Search

Emulsifier-free emulsion polymerizations based on styrene\\/potassium persulfate\\/water (St\\/kps\\/H2O) in the presence of a relatively hydrophilic comonomer, such as vinyl acetate (VAc) or methyl methacrylate (MMA), or the nonpolar solvent, such as ethyl acetate (EAc) or methyl isobutyrate (MIB) having structural similarity with VAc and MMA respectively, or the polar solvent such as glycerin or acetone etc., have been carried out.

Jinn-Luh Ou; Jia-Kuen Yang; Hui Chen

2001-01-01

159

SYSTEM PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP  

E-print Network

AUG 1979 SYSTEM PERFORMANCE OF A STIRLING ENGINE POWERED HEAT ACTIVATED HEAT PUMP W. D. Richards W of the subsystem compo- nents, especially between the free piston Stirling engine and the free piston linear),* and a decision was made to proceed with the Prototype Development. Superiority of a Stirling engine over other

Oak Ridge National Laboratory

160

Oxidative Alkaline leaching of Americium from simulated high-level nuclear waste sludges  

SciTech Connect

Oxidative alkaline leaching has been proposed to pre-treat the high-level nuclear waste sludges to remove some of the problematic (e.g., Cr) and/or non-radioactive (e.g., Na, Al) constituents before vitrification. It is critical to understand the behavior of actinides, americium and plutonium in particular, in oxidative alkaline leaching. We have studied the leaching behavior of americium from four different sludge simulants (BiPO{sub 4}, BiPO{sub 4 modified}, Redox, PUREX) using potassium permanganate and potassium persulfate in alkaline solutions. Up to 60% of americium sorbed onto the simulants is leached from the sludges by alkaline persulfate and permanganate. The percentage of americium leached increases with [NaOH] (between 1.0 and 5.0 M). The initial rate of americium leaching by potassium persulfate increases in the order BiPO{sub 4} sludge < Redox sludge < PUREX sludge. The data are most consistent with oxidation of Am{sup 3+} in the sludge to either AmO{sub 2}{sup +} or AmO{sub 2}{sup 2+} in solution. Though neither of these species is expected to exhibit long-term stability in solution, the potential for mobilization of americium from sludge samples would have to be accommodated in the design of any oxidative leaching process for real sludge samples.

Reed, Wendy A.; Garnov, Alexander Yu.; Rao, Linfeng; Nash, Kenneth L.; Bond, Andrew H.

2004-01-23

161

[Chemical oxidants for remediation of BTEX-contaminated soils at coking sites].  

PubMed

An enclosed reactor was used to evaluate Fenton reagent, modified Fenton reagent, potassium permanganate and activated persulfate for removal of benzene, toluene, ethyl benzene, and xylene (BTEX) from soil at contaminated industrial coking sites. The results showed that Fenton reagent and modified Fenton reagent were the optimum oxidants for removing BTEX, and these oxidants decreased the concentration of BTEX in soils by 83% and 73%, respectively. The proportion of BTEX volatilized from the soil was < 4% in both cases, and the rates of BTEX removal from the whole system were 80% and 71%. More than 65% of xylene was removed after treatment with Fenton reagent and modified Fenton reagent. In contrast, benzene, toluene were more resistant to oxidation, and ethyl benzene was the most resistant of these compounds. The concentration of BTEX decreased to some extent when permanganate and activated persulfate were used as oxidants. However, the proportions of volatilized BTEX were 83% and 77% for permanganate and activated persulfate, respectively. This indicates that they could stimulate the desorption and volatilization of BTEX, while they were ineffective for removing BTEX from the environment. PMID:21634187

Zhao, Dan; Yan, Xiu-Lan; Liao, Xiao-Yong; Tu, Shu-Xin; Shi, Qi-Wen

2011-03-01

162

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  

USGS Publications Warehouse

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 suggests, however, that this apparent low bias resulted from nitrate interference in the Kjeldahl digestion method rather than low nitrogen recovery by the alkaline persulfate digestion method. Typically, differences between means of Kjeldahl nitrogen and nitrate-corrected alkaline persulfate nitrogen in low-nitrate concentration (< 0.1 milligram nitrate nitrogen per liter) subsets of filtered surface- and ground-water samples were statistically equivalent to zero at the p =level.Paired analytical results for dissolved and total phosphorus in Kjeldahl and alkaline persulfate digests were directly comparable because both digestion methods convert all forms of phosphorus in water samples to orthophosphate. On the basis of two-population paired t-test statistics, the means of all Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations (2,093 paired results) were not significantly different from zero at the p = 0.05 level. For some subsets of these data, which were grouped according to water type and flow conditions at the time of sample collection, differences between means of Kjeldahl phosphorus and alkaline persulfate phosphorus concentrations were not equivalent to zero at the p = 0.05 level. Differences between means of these subsets, however, were less than the method detection limit for phosphorus (0.007 milligram phosphorus per liter) by the alkaline persulfate digestion method, and were therefore analytically insignificant.This report provides details of the alkaline persulfate digestion procedure, interference studies, recovery of various nitrogen- and phosphorus-containing compounds, and other analytical figures of merit. The automated air-segmented continuous flow methods developed to determine nitrate and orthophosphate in the alkaline persulfate digests also are described. About 125 microliters of digested sample are required to determine nitrogen and phosphorus in parallel at a rate of about 100 samples per hour with less than 1-percent sample in

Patton, Charles J.; Kryskalla, Jennifer R.

2003-01-01

163

Experimental Evaluation of Catalyzed Hydrogen Peroxide and Sodium Persulfate for Destruction of BTEX Contaminants  

Microsoft Academic Search

Due to the toxicity and prevalence of BTEX contaminants (benzene, toluene, ethylbenzene, and xylenes) at hazardous waste sites, approaches for their remediation are of interest, especially those that particularly address benzene, which is often the limiting factor for achieving regulatory cleanup at these contaminated sites. In situ chemical oxidation (ISCO) is a viable technology for BTEX destruction, and hydrogen peroxide

Michelle L. Crimi; Jesse Taylor

2007-01-01

164

Oxidation of trivalent americium, curium, and terbium in solutions of sodium paratungstate  

SciTech Connect

In the further study of the behavior of the actinides and lanthanides in solutions of heteropoly-compounds, the authors succeed in finding conditions under which the formation of americium (IV), curium (IV), and terbium (IV) decatungstates is observed. The results of experiments along this line are brieflyoutlined. It is shown that trivalent americium, curium, and terbium are oxidzed by heating with persulfate not only in solutions ofunsaturated heteropolytungstates but also in solutions of isopoly-compounds of tungsten. However, the degree of oxidation of curium and terbium (III) in the latter case is appreciably lover. In addition to persulfate ions, ozone can be used for the oxidation of americium (III) in solutions of sodium paratungstate.

Fedoseev, A.M.; Krot, N.N.; Spitsyn, V.I.

1986-09-01

165

Tissue Engineering: Fabrication of Anisotropic Neurodurable Scaffold via Molecular Disposition of Persulfate-Mediated Polymer Slicing and Complexation  

E-print Network

Abstract: 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 × 10 6 Da) compared with known acrylamide that has a GE = 83%, GR = 178%, IV = 3.901 dL/g and MW = 1.22 × 10 6 Da. Image processing analysis of SEM images of the newly graftedInt. J. Mol. Sci. 2012, 13 13967 neurodurable scaffold was undertaken based on the polymer-pore threshold. Attenuated Total Reflectance-FTIR spectral analyses in conjugation with DSC were used for the

Pradeep Kumar; Yahya E. Choonara; Lisa C. Du Toit; Girish Modi; Dinesh Naidoo; Viness Pillay

2012-01-01

166

Pentachlorophenol removal from aqueous solutions by microwave/persulfate and microwave/H2O2: a comparative kinetic study  

PubMed Central

Pentachlorophenol (PCP) is one of the most fungicides and pesticides used in wood protection. Poisoning from PCP may be happened in dermal absorption, and respiration or ingestion. With regard to health and environmental effects of PCP, many methods were studied for its removal. Microwave assisted other methods are environmental friendly, safety, and economical method, therefore, in this study; a modified domestic microwave assisted hydrogen peroxide (MW/H2O2) and sodium persulfate (MW/SPS) was used for PCP removal from aqueous solutions. PCP removal rate was measured under different factors such as pH, energy intensity, SPS, H2O2 concentration, Tert- butyl alcohol (TBA) and chemical oxygen demand (COD). The concentration changes of PCP were determined using spectrophotometer and HPLC spectra, respectively. The best removal PCP rate obtained in condition of pH of 11, 0.02 mol L?1 of SPS, 0.2 mol L?1 of H2O2 and energy intensity of 600 W. Moreover, COD removals in MW/H2O2 and MW/SPS process were 83% and 94%, respectively, also TBA test decreased 15% and 3% of PCP removal in MW/SPS and MW/H2O2 processes respectively. Experimental results indicated that sulfate radical was stronger than hydroxyl radical and examinations order reaction was in first order. In this study, was cleared that MW/SPS process was more effective than MW/H2O2 process in PCP removal. PMID:25018879

2014-01-01

167

Transition metal\\/UV-based advanced oxidation technologies for water decontamination  

Microsoft Academic Search

This study explores the effect of ultraviolet (UV) light radiation and\\/or transition metals (M) for the activation of common oxidants (Ox) with the objective of treating recalcitrant organic contaminants in water. Hydrogen peroxide, potassium peroxymonosulfate and potassium persulfate were combined with iron, cobalt and silver, respectively, and\\/or with UV light (254nm) and were tested for the treatment of 2,4-dichlorophenol (2,4-DCP).

George P. Anipsitakis; Dionysios D. Dionysiou

2004-01-01

168

Degradation of acetic acid with sulfate radical generated by persulfate ions photolysis  

Microsoft Academic Search

The photolysis of S2O82- was studied for the removal of acetic acid in aqueous solution and compared with the H2O2\\/UV system. The SO4- radicals generated from the UV irradiation of S2O82- ions yield a greater mineralization of acetic acid than the OH radicals. Acetic acid is oxidized by SO4- radicals without significant formation of intermediate by-products. Increasing system pH results

Justine Criquet; Nathalie Karpel Vel Leitner

2009-01-01

169

Simultaneous determination of total nitrogen and total phosphorus in freshwater samples using persulfate digestion  

Microsoft Academic Search

The accuracy and precision of total nitrogen (T?N) and total phosphorus (T?P) determinations in freshwater samples by the simultaneous digestion method using an oxidizing reagent solution of NaOH?K2S2O8 were assessed. Detection limits based on the blank test of nitrogen and phosphorus were 0.02 mgN\\/1 and 0.001 mgP\\/1, respectively. This simultaneous digestion method gave not only a high recovery and reproducibility

Masaaki Hosomi; Ryuichi Sudo

1986-01-01

170

Preparation and properties of a compound containing nickel in highest oxidation states  

SciTech Connect

The purpose of this paper is to obtain nickel hydroxide oxide of the optimal composition both by chemical and by electrochemical oxidation for use as the cathode material in alkaline batteries. The authors selected the oxidation conditions (oxidant, component ratio) for production of gamma-NiOOH; hydrogen peroxide, potassium permanganate, and potassium persulfate were used as oxidants. Gamma-NiOOH was also obtained by electrochemical oxidation of nickel (II) oxide hydrate in alkaline solutions. In samples obtained by electrochemical oxidation virtually 100% of the nickel is in the highly oxidized state. It is shown that gamma-NiOOH obtained by both chemical and electrochemical oxidation is a complex individual compound containing nickel and in the highest oxidation states, Ni/sup 3 +/ and Ni/sup 4 +/, together with salt-forming potassium ions and water molecules. The gamma-NiOOH obtained may be used with success in galvanic cells.

Nikol'skii, V.A.; Bekreneva, L.A.; Garmash, L.A.; Makashev, Yu.A.; Mikhailova, K.A.; Raikhel'son, L.B.; Shchelkunova, L.I.

1986-04-10

171

Divalent cations potentiate TRPV1 channel by lowering the heat activation threshold  

PubMed Central

Transient receptor potential vanilloid type 1 (TRPV1) channel responds to a wide spectrum of physical and chemical stimuli. In doing so, it serves as a polymodal cellular sensor for temperature change and pain. Many chemicals are known to strongly potentiate TRPV1 activation, though how this is achieved remains unclear. In this study we investigated the molecular mechanism underlying the gating effects of divalent cations Mg2+ and Ba2+. Using a combination of fluorescence imaging and patch-clamp analysis, we found that these cations potentiate TRPV1 gating by most likely promoting the heat activation process. Mg2+ substantially lowers the activation threshold temperature; as a result, a significant fraction of channels are heat-activated at room temperature. Although Mg2+ also potentiates capsaicin- and voltage-dependent activation, these processes were found either to be not required (in the case of capsaicin) or insufficient (in the case of voltage) to mediate the activating effect. In support of a selective effect on heat activation, Mg2+ and Ba2+ cause a Ca2+-independent desensitization that specifically prevents heat-induced channel activation but does not prevent capsaicin-induced activation. These results can be satisfactorily explained within an allosteric gating framework in which divalent cations strongly promote the heat-dependent conformational change or its coupling to channel activation, which is further coupled to the voltage- and capsaicin-dependent processes. PMID:24344247

Cao, Xu; Ma, Linlin; Yang, Fan

2014-01-01

172

Activating persulfate by Fe? coupling with weak magnetic field: performance and mechanism.  

PubMed

Weak magnetic field (WMF) and Fe(0) were proposed to activate PS synergistically (WMF-Fe(0)/PS) to degrade dyes and aromatic contaminants. The removal rates of orange G (OG) by WMF-Fe(0)/PS generally decreased with increasing initial pH (3.0-10.0) and increased with increasing Fe(0) (0.5-3.0 mM) or PS dosages (0.5-3.0 mM). Compared to its counterpart without WMF, the WMF-Fe(0)/PS process could induce a 5.4-28.2 fold enhancement in the removal rate of OG under different conditions. Moreover, the application of WMF significantly enhanced the decolorization rate and the mineralization of OG. The degradation rates of caffeine, 4-nitrophenol, benzotriazole and diuron by Fe(0)/PS were improved by 2.1-11.1 fold due to the superimposed WMF. Compared to many other sulfate radical-based advanced oxidation technologies under similar reaction conditions, WMF-Fe(0)/PS technology could degrade selected organic contaminants with much greater rates. Sulfate radical was identified to be the primary radical species responsible for the OG degradation at pH 7.0 in WMF-Fe(0)/PS process. This study unraveled that the presence of WMF accelerated the corrosion rate of Fe(0) and thus promoted the release of Fe(2+), which induced the increased production of sulfate radicals from PS and promoted the degradation of organic contaminants. Employing WMF to enhance oxidation capacity of Fe(0)/PS is a novel, efficient, promising and environmental-friendly method since it does not need extra energy and costly reagents. PMID:24934323

Xiong, Xinmei; Sun, Bo; Zhang, Jing; Gao, Naiyun; Shen, Jimin; Li, Jialing; Guan, Xiaohong

2014-10-01

173

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

PubMed Central

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, superior hydrophilicity as well as surface charge due to the acrylic chains. Additionally, these results suggested that the porous PAAm-g-CHT scaffold may act as a potential neural cell carrier. PMID:23203044

Kumar, Pradeep; Choonara, Yahya E.; du Toit, Lisa C.; Modi, Girish; Naidoo, Dinesh; Pillay, Viness

2012-01-01

174

Evaluation of activated carbon for remediating benzene contamination: adsorption and oxidative regeneration.  

PubMed

This study investigated the potential usage of activated carbon (AC) as a permeable reactive barrier material for the adsorption of benzene contaminant. Sodium persulfate (SPS) or pyrite (FeS(2)) activated SPS oxidation was used for the regeneration of spent AC. Results indicate that persulfate oxidation of AC caused a loss of electrons and a reduction in adsorptive capacity due to the formation of acidic functional groups on the AC. Concerning the reactants that can be used for oxidation of the benzene contaminants, SPS/FeS(2)/AC, as oppose to SPS/AC, can achieve benzene destruction in both the aqueous and the sorbed phases. Furthermore, regeneration of benzene spent AC by SPS or SPS/FeS(2) revealed that SPS oxidation resulted primarily in desorption of benzene over direct oxidation of AC sorbed benzene. In contrast, the SPS/FeS(2) system achieved complete oxidation of desorbed benzene in the aqueous phase while also oxidizing sorbed benzene. Results of re-adsorption show that oxidative regeneration recovered around 70% of the AC adsorption sites and the remaining capacity was mostly occupied by the residual benzene on the AC. This study demonstrates that SPS or FeS(2) activated SPS oxidation is an effective alternative method for the regeneration of spent AC. PMID:20621415

Liang, Chenju; Chen, Yan-Jyun

2010-10-15

175

Exploration of the Role of Heat Activation in Enhancing Serpentine Carbon Sequestration Reactions  

SciTech Connect

As compared with other candidate carbon sequestration technologies, mineral carbonation offers the unique advantage of permanent disposal via geologically stable and environmentally benign carbonates. The primary challenge is the development of an economically viable process. Enhancing feedstock carbonation reactivity is key. Heat activation dramatically enhances aqueous serpentine carbonation reactivity. Although the present process is too expensive to implement, the materials characteristics and mechanisms that enhance carbonation are of keen interest for further reducing cost. Simultaneous thermogravimetric and differential thermal analysis (TGA/DTA) of the serpentine mineral lizardite was used to isolate a series of heat-activated materials as a function of residual hydroxide content at progressively higher temperatures. Their structure and composition are evaluated via TGA/DTA, X-ray powder diffraction (including phase analysis), and infrared analysis. The meta-serpentine materials that were observed to form ranged from those with longer range ordering, consistent with diffuse stage-2 like interlamellar order, to an amorphous component that preferentially forms at higher temperatures. The aqueous carbonation reaction process was investigated for representative materials via in situ synchrotron X-ray diffraction. Magnesite was observed to form directly at 15 MPa CO{sub 2} and at temperatures ranging from 100 to 125 C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder.

McKelvy, M.J.; Chizmeshya, A.V.G.; Diefenbacher, J.; Bearat, H.; Wolf, G. (ASU)

2005-03-29

176

Alkene oxidation catalyzed by a ruthenium-substituted heteropolyanion, SiRu(L)W sub 11 O sub 39 : The mechanism of the periodate mediated oxidative cleavage  

SciTech Connect

A ruthenium-substituted heteropolyanion SiRu(H{sub 2}O)W{sub 11}O{sub 39}{sup 5{minus}} was synthesized and characterized. The hydrophobic quaternary ammonium salt of the heteropolyanion ((C{sub 6}H{sub 13}){sub 4}N){sub 5}SiRu{sup III}(H{sub 2}O)W{sub 11}O{sub 39} was used as a catalyst for the oxidation of alkenes with tert-butyl hydroperoxide, potassium persulfate, iodosobenzene, and sodium periodate as primary oxidants. Reactivity and selectivity were found to be dependent on the oxidant used; several different types of oxidation processes could be identified including allylic oxidation, epoxidation, and oxidative cleavage. Use of sodium periodate as oxidant enabled selective bond cleavage with aldehydes as the exclusive product.

Neumann, R.; Abu-Gnim, C. (Hebrew Univ. of Jerusalem (Israel))

1990-08-01

177

Feasibility study on an oxidant-injected permeable reactive barrier to treat BTEX contamination: Adsorptive and catalytic characteristics of waste-reclaimed adsorbent  

Microsoft Academic Search

The adsorptive and catalytic characteristics of waste-reclaimed adsorbent (WR), which is a calcined mixture of bottom-ash and dredged-soil, was investigated for its application to treating BTEX contamination. BTEX adsorption in WR was 54%, 64%, 62%, and 65%, respectively, for a 72h reaction time. Moreover, the catalytic characteristics of WR were observed when three types of oxidation systems (i.e., H2O2, persulfate

Si-Hyun Do; Yong-Jae Kwon; Sung-Ho Kong

2011-01-01

178

The heat-activated solderless passivation (HASP) technique for correcting nonpassive-fitting bars without soldering.  

PubMed

The fabrication of a cast noble alloy overdenture bar entails a variety of clinical and laboratory steps, each of which can potentially generate distortions that result in the non-passive fit of the finished product. Traditional laboratory procedures to correct the misfit of cast bars entail sectioning the bar, then reconnecting the bar segments by soldering or welding. After such procedures, research has shown that the bar may still not fit passively on the implant abutments in the patient's mouth. In addition, the overall structure of the bar would be weaker at the mended joints. The heat-activated solderless passivation (HASP) technique involves a two-step process of correcting the master cast, then attaching the cast bar to a soldering index and applying heat to relax the metal until the tensile forces of the retention screws pull the bar into a passive fit. PMID:12704951

Ford, Thomas G

2003-01-01

179

Carbon isotopic analysis of dissolved organic carbon in produced water brines by wet chemical oxidation and cavity ring-down spectroscopy  

NASA Astrophysics Data System (ADS)

We have adapted the Picarro iTOC CRDS isotope analyzer for analysis of produced water brines via wet chemical persulfate oxidation. In particular, we developed strategies and techniques for overcoming the limitation imposed by low oxidation efficiencies due to the chloride ion interference with persulfate oxidation. These techniques are important for understanding the origin of dissolved organic carbon in subsurface fluids from oilfields, as a tracer of fracking fluids in groundwater, and in interpreting changes in groundwater DOC as a result of microbial activity including oil biodegradation or microbially enhanced oil recovery. We describe the limitations of this new instrument for the analysis of DOC in brines including sample requirements, matrix effects, and the effect of DOC composition on reaction efficiency and isotopic measurements. We compare strategies including anion exchange cartridges, persulfate reactant concentrations, and reaction time. The CRDS analysis of DOC in brines is a useful tool for understanding the origin and fate of DOC and is a potentially powerful tool to identifiy evidence of contamination due to hydrofracturing chemicals that have a distinctive carbon isotopic signature relative to natural brine.

Thomas, B.; Conaway, C.; Kharaka, Y. K.; Saad, N.

2012-12-01

180

The Effects of Heat Activation on Bacillus Spore Germination, with Nutrients or under High Pressure, with or without Various Germination Proteins.  

PubMed

Nutrient germination of spores of Bacillus species occurs through germinant receptors (GRs) in spores' inner membrane (IM) in a process stimulated by sublethal heat activation. Bacillus subtilis spores maximum germination rates via different GRs required different 75°C heat activation times: 15 min for l-valine germination via the GerA GR and 4 h for germination with the l-asparagine-glucose-fructose-K(+) mixture via the GerB and GerK GRs, with GerK requiring the most heat activation. In some cases, optimal heat activation decreased nutrient concentrations for half-maximal germination rates. Germination of spores via various GRs by high pressure (HP) of 150 MPa exhibited heat activation requirements similar to those of nutrient germination, and the loss of the GerD protein, required for optimal GR function, did not eliminate heat activation requirements for maximal germination rates. These results are consistent with heat activation acting primarily on GRs. However, (i) heat activation had no effects on GR or GerD protein conformation, as probed by biotinylation by an external reagent; (ii) spores prepared at low and high temperatures that affect spores' IM properties exhibited large differences in heat activation requirements for nutrient germination; and (iii) spore germination by 550 MPa of HP was also affected by heat activation, but the effects were relatively GR independent. The last results are consistent with heat activation affecting spores' IM and only indirectly affecting GRs. The 150- and 550-MPa HP germinations of Bacillus amyloliquefaciens spores, a potential surrogate for Clostridium botulinum spores in HP treatments of foods, were also stimulated by heat activation. PMID:25681191

Luu, Stephanie; Cruz-Mora, Jose; Setlow, Barbara; Feeherry, Florence E; Doona, Christopher J; Setlow, Peter

2015-04-15

181

Some Observations on the Emulsion Polymerization of Ethyl Methacrylate Initiated by Potassium Persulfate at 50°C in a Phosphate Buffer Solution of pH 6.85 and at a Low Monomer\\/Water Ratio  

Microsoft Academic Search

The emulsion polymerization of ethyl methacrylate initiated by the potassium persulfate (I) at 50°C in the presence of an anionic detergent (S), i.e., sodium lauryl sulfate at a low monomer\\/water ratio, has been ineestigated kinetically by the coneentional dilatometric and graeimetric methods in a phosphate buffer solution of pH 6.85. The number of latex particles per mL of the aqueous

T. K. Paul; M. Banerjee; R. S. Konar

1981-01-01

182

Probing the radical chemistry in UV/persulfate-based saline wastewater treatment: kinetics modeling and byproducts identification.  

PubMed

The effect of Cl(-) on the oxidative degradation of Acid Orange 7 (AO7) was investigated in UV/S2O8(2-) system to elucidate the chlorination pathways in saline wastewaters. Lower amount of Cl(-) as well as Br(-) enhanced the decoloration of AO7, but such promotion effect reduced gradually with the increasing halide ion dosage. The dye mineralization was found to be inhibited by Cl(-), especially under acidic conditions. Results of kinetics modeling demonstrated that the fraction of different oxidizing radicals largely depended on the content of Cl(-). At the initial pH of 6.5, Cl2(-) was much more abundant than SO4(-). The significance of Cl2(-) for AO7 degradation increased with the increasing Cl(-) concentration and overwhelmed that of SO4(-) at [Cl(-)]>1mM. Without Cl(-), SO4(-) was the predominant radical for AO7 degradation under acidic conditions, while OH prevailed gradually at higher pH. Under high salinity conditions, more OH can be formed and contributed to the dye degradation especially in alkaline medium, leading to higher destruction efficiency of AO7. Several chlorinated byproducts were detected in the presence of chloride ions, and SO4(-)/Cl2(-)-based degradation pathways of AO7 were proposed. This work provides further understanding of the complex reaction mechanisms for SO4(-)-based advanced oxidation processes in chloride-rich environments. PMID:24873714

Yuan, Ruixia; Wang, Zhaohui; Hu, Yin; Wang, Baohui; Gao, Simeng

2014-08-01

183

oxidation of americium(iii) and the stability of americium(iv) and americium(vi) in solutions of sulfuric and perchloric acids  

SciTech Connect

The oxidation of weighable amounts of americium in solutionsof sulfuric and perchloric acids was investigated by a spectrophotometric method. The stability of americium(IV) and (VI) in mineral acids was studied. A method was developed for the production of tetravalent americium in solutions of 0.1-3 M H/sub 2/SO/sub 4/ and 0.1-1 M HClO/sub 4/, containing potassium phosphotungstate K/sub 10/P/sub 2/W/sub 17/O/sub 61/ an an oxidizing mixture - a silver salt and ammonium persulfate.

Milyukova, M.S.; Litvina, M.N.; Myasoedov, B.F.

1986-07-01

184

A High-Throughput Optical Screening Method for the Optimization of Colloidal Water Oxidation Catalysts  

E-print Network

containing tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy)3 2+ ) and persulfate. The array of reaction solutions evolution from Ru(bpy)3 2+, using persulfate as a sacrificial electron acceptor, have been achieved using Ir

185

Direct Trifluoromethylthiolation of Unactivated C(sp(3) )?H Using Silver(I) Trifluoromethanethiolate and Potassium Persulfate.  

PubMed

A practical and efficient method for the direct trifluoromethylthiolation of unactivated C(sp(3) )?H bonds by AgSCF3 /K2 S2 O8 under mild conditions is described. The reaction has a good functional-group tolerance and good selectivity. Initial mechanistic investigations indicate that the reaction may involve a radical process in which K2 S2 O8 plays key roles in both the activation of the C(sp(3) )?H bond and the oxidation of AgSCF3 . PMID:25707945

Wu, Hao; Xiao, Zhiwei; Wu, Junhui; Guo, Yong; Xiao, Ji-Chang; Liu, Chao; Chen, Qing-Yun

2015-03-23

186

Incipient hydrous oxide species as inhibitors of reduction processes at noble metal electrode  

SciTech Connect

Evidence is presented to illustrate the important role of hydrous oxide in noble metal electrocatalysis. It was demonstrated, for instance, that in the case of gold in acid the onset/termination potential, under potential sweep conditions, for hydrazine oxidation and persulfate or iodate reduction occurred at the end of the hydrous oxide reduction peak (recorded for a thick film growth grown by potential multicycling); there was also a maximum in the faradaic ac response for gold in acid in the same region. Both gold and platinum were investigated in acid and base electrolytes. In some cases a range of potential, rather than a discrete value, was found to be involved, different species react with (or are inhibited by) different types (or coverages) of these submonolayer species. In some, possibly electrocatalytically nondemanding, reduction reactions the hydrous oxide seemed to have little effect.

Burke, L.D.; O'Sullivan, J.F.; O'Dwyer, K.J.; Scannell, R.A.; Ahern, M.J.G.; McCarthy, M.M. (Dept. of Chemistry, Univ. College, Cork (IE))

1990-08-01

187

Process for the oxidation of materials in water at supercritical temperatures utilizing reaction rate enhancers  

SciTech Connect

A method is described for substantially completely oxidizing combustible materials in which an aqueous stream bearing the combustible materials is reacted in the presence of an oxidant comprising diatomic oxygen and at a temperature greater than the critical temperature of water and at a pressure greater than about 25 bar, within a reactor for a period of less than about 5 minutes to produce a reaction product stream, wherein the reaction is initiated in the presence of a rate enhancer comprising at least one oxidizing agent in addition to said oxidant selected from the group consisting of ozone, hydrogen peroxide, salts containing persulfate, salts containing permanganate, nitric acid, salts containing nitrate, oxyacids of chlorine and their corresponding salts, hypochlorous acid, salts containing hypochlorite, chlorous acid, salts containing chlorite, chloric acid, salts containing chlorate, perchloric acid, and salts containing perchlorate.

Swallow, K.C.; Killilea, W.R.; Hong, G.T.; Bourhis, A.L.

1993-08-03

188

[Effects of particle size of zero-valent iron on the reactivity of activating persulfate and kinetics for the degradation of acid orange 7].  

PubMed

This research described the heterogeneous reactions of persulfate with different particle sizes of zero-valent iron (including 1 mm-ZVI,150 ?m-ZVI,50 nm-ZVI) for degradation of acid orange 7(AO7) , and studied the kinetics and intermediate products of AO7 under these systems. The results demonstrated that these three types of ZVI were efficient in promoting the degradation of AO7, the degradation efficiencies of AO7 were 43% , 97% , and 100% within 90 min respectively, in the 1 mm-ZVI,150 ?m-ZVI and 50 nm- ZVI systems, respectively. With the results of kinetic fitting models, the pseudo first-order kinetics exhibited better fitting results in the 1 mm-ZVI,150 ?m-ZVI systems, while the second-order kinetics exhibited better fitting results in the 50 nm-ZVI system. And the different ZVI types exhibited difference on the AO7 degradation rate constant, which ranged as 50 nm-ZVI > 150 ?m-ZVI > 1 mm-ZVI. The iron corrosion products coating on the ZVI after reaction were composed of ?-Fe2 O3 and some Fe3O4 in the 1 mm-ZVI system while that consisted of Fe3O4 and ?-Fe2O3, FeOOH respectively, in thel50 ?m-ZVI and 50 nm-ZVI systems,. Which were identified by scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) and Raman spectroscopy. Some intermediate products, including 2-naphthalenol, 2-methylphenol, 4-ethyl- 3-methyl-phenol, isoindole- 1,3-dione and phthalic acid et al. were identified by GC/MS measurement. Both UV-vis absorbance spectra and GC/MS determination indicated that there was difference in degradation paths of AO7 between the three systems. PMID:25518660

Li, Huan-xuan; Wan, Jin-quan; Ma, Yong-wen; Huang, Ming-zhiz; Wang, Yan; Chen Yang, Mei

2014-09-01

189

Effects of chemical oxidants on perfluoroalkyl acid transport in one-dimensional porous media columns.  

PubMed

In situ chemical oxidation (ISCO) is a remediation approach that is often used to remediate soil and groundwater contaminated with fuels and chlorinated solvents. At many aqueous film-forming foam-impacted sites, perfluoroalkyl acids (PFAAs) can also be present at concentrations warranting concern. Laboratory experiments were completed using flow-through one-dimensional columns to improve our understanding of how ISCO (i.e., activated persulfate, permanganate, or catalyzed hydrogen peroxide) could affect the fate and transport of PFAAs in saturated porous media. While the resultant data suggest that standard ISCO is not a viable remediation strategy for PFAA decomposition, substantial changes in PFAA transport were observed upon and following the application of ISCO. In general, activated persulfate decreased PFAA transport, while permanganate and catalyzed hydrogen peroxide increased PFAA transport. PFAA sorption increased in the presence of increased aqueous polyvalent cation concentrations or decreased pH. The changes in contaminant mobility were greater than what would be predicted on the basis of aqueous chemistry considerations alone, suggesting that the application of ISCO results in changes to the porous media matrix (e.g., soil organic matter quality) that also influence transport. The application of ISCO is likely to result in changes in PFAA transport, where the direction (increased or decreased transport) and magnitude are dependent on PFAA characteristics, oxidant characteristics, and site-specific factors. PMID:25621878

McKenzie, Erica R; Siegrist, Robert L; McCray, John E; Higgins, Christopher P

2015-02-01

190

Study of water adsorption on activated carbons with different degrees of surface oxidation  

SciTech Connect

A carbon of wood origin was oxidized with different oxidizing agents (nitric acid, hydrogen peroxide, and ammonium persulfate). The microstructural properties of the starting material and the oxidized samples were characterized using sorption of nitrogen. The surface acidity was determined using Boehm titration and potentiometric titration. The changes in the surface chemistry were also studied by diffuse reflectance FTIR. Water adsorption isotherms were measured at three different temperatures close to ambient (relative pressure from 0.001 to 0.3). From the isotherms the heats of adsorption were calculated using a virial equation. The results indicated that the isosteric heats of water adsorption are affected by the surface heterogeneity only at low surface coverage. In all cases the limiting heat of adsorption was equal to the heat of water condensation (45 kJ/mol).

Salame, I.I.; Bandosz, T.J. [City Coll. of New York, NY (United States). Dept. of Chemistry] [City Coll. of New York, NY (United States). Dept. of Chemistry; [City Univ. of New York, NY (United States). Graduate School

1999-02-15

191

Catalytic-Oxidative Leaching of Low-Grade Complex Zinc Ore by Cu (II) Ions Produced from Copper Ore in Ammonia-Ammonium Sulfate Solution  

NASA Astrophysics Data System (ADS)

The catalytic-oxidative leaching of a mixed ore, which consists of low-grade oxide copper ore and oxide zinc ore containing ZnS, was investigated in ammonia-ammonium sulfate solution. The effect of the main parameters, such as mass ratio of copper ore to zinc ore, liquid-to-solid ratio, concentration of lixivant, leaching time, and temperature, was studied. The optimal leaching conditions with a maximum extraction of Cu 92.6 pct and Zn 85.5 pct were determined as follows: the mass ratio of copper ore to zinc ore 4/10 g/g, temperature 323.15 K (50 °C), leaching time 6 hours, stirring speed 500 r/min, liquid-to-solid ratio 3.6/1 cm3/g, concentration of lixivant including ammonia 2.0 mol/dm3, ammonium sulfate 1.0 mol/dm3, and ammonium persulfate 0.3 mol/dm3. It was found that ZnS in the oxide zinc ore could be extracted with Cu(II) ion, which was produced from copper ore and was used as the catalyst in the presence of ammonium persulfate.

Liu, Zhi Xiong; Yin, Zhou Lan; Hu, Hui Ping; Chen, Qi Yuan

2012-10-01

192

Reduction of persulfate ion by carbon monoxide in alkaline medium: the effect of stoichiometric and astoichiometric components on the reaction Kinetics  

SciTech Connect

The effect of the concentration of oxidant, cadalyst, and various ligands on the kinetics of the oxidation of CO have been studied kinetically, potentiometrically, and spectrometrically, and a general mechanism for the process is proposed.

Abilov, M.T.; Golodov, V.A.

1986-06-01

193

Magnetoresistive polyaniline/multi-walled carbon nanotube nanocomposites with negative  

E-print Network

with Cr(VI) as oxidant and MWNTs/PANI nanocomposites with ammonium persulfate (APS) as oxidant, a room% is reported in 5 wt% MWNTs/ PANI nanocomposites synthesized with ammonium persulfate (APS) as oxidant.9

Guo, John Zhanhu

194

Ordered mesoporous cobalt oxide as highly efficient oxygen evolution catalyst.  

PubMed

Oxygen evolution from water by use of earth-abundant element-based catalysts is crucial for mass solar fuel production. In this report, a mesoporous cobalt oxide with an ultrahigh surface area (up to 250 m(2)·g(-1)) has been fabricated through Mg substitution in the mesoporous Co3O4 spinel, followed by a Mg-selective leaching process. Approximately a third of Mg cations were removed in the leaching process, resulting in a highly porous cobalt oxide with a significant amount of defects in the spinel structure. The activated mesoporous cobalt oxide exhibited high oxygen evolution activities in both the visible-light-driven [Ru(bpy)3](2+)-persulfate system and the Ce(4+)/Ce(3+) chemical water oxidation system. Under a strong acidic environment, a high turnover frequency (TOF) of ~2.2 × 10(-3) s(-1) per Co atom was achieved, which is more than twice the TOF of traditional hard-templated, mesoporous Co3O4. PMID:23448405

Rosen, Jonathan; Hutchings, Gregory S; Jiao, Feng

2013-03-20

195

Graphene-assisted room-temperature synthesis of 2D nanostructured hybrid electrode materials: dramatic acceleration of the formation rate of 2D metal oxide nanoplates induced by reduced graphene oxide nanosheets.  

PubMed

A new prompt room temperature synthetic route to 2D nanostructured metal oxide-graphene-hybrid electrode materials can be developed by the application of colloidal reduced graphene oxide (RGO) nanosheets as an efficient reaction accelerator for the synthesis of ?-MnO2 2D nanoplates. Whereas the synthesis of the 2D nanostructured ?-MnO2 at room temperature requires treating divalent manganese compounds with persulfate ions for at least 24 h, the addition of RGO nanosheet causes a dramatic shortening of synthesis time to 1 h, underscoring its effectiveness for the promotion of the formation of 2D nanostructured metal oxide. To the best of our knowledge, this is the first example of the accelerated synthesis of 2D nanostructured hybrid material induced by the RGO nanosheets. The observed acceleration of nanoplate formation upon the addition of RGO nanosheets is attributable to the enhancement of the oxidizing power of persulfate ions, the increase of the solubility of precursor MnCO3, and the promoted crystal growth of ?-MnO2 2D nanoplates. The resulting hybridization between RGO nanosheets and ?-MnO2 nanoplates is quite powerful not only in increasing the surface area of manganese oxide nanoplate but also in enhancing its electrochemical activity. Of prime importance is that the present ?-MnO2 -RGO nanocomposites show much superior electrode performance over most of 2D nanostructured manganate systems including a similar porous assembly of RGO and layered MnO2 nanosheets. This result underscores that the present RGO-assisted solution-based synthesis can provide a prompt and scalable method to produce nanostructured hybrid electrode materials. PMID:23559338

Sung, Da-Young; Gunjakar, Jayavant L; Kim, Tae Woo; Kim, In Young; Lee, Yu Ri; Hwang, Seong-Ju

2013-05-27

196

Miniaturized dielectric barrier discharge carbon atomic emission spectrometry with online microwave-assisted oxidation for determination of total organic carbon.  

PubMed

A simple, rapid, and portable system consisted of a laboratory-built miniaturized dielectric barrier discharge atomic emission spectrometer and a microwave-assisted persulfate oxidation reactor was developed for sensitive flow injection analysis or continuous monitoring of total organic carbon (TOC) in environmental water samples. The standard/sample solution together with persulfate was pumped to the reactor to convert organic compounds to CO2, which was separated from liquid phase and transported to the spectrometer for detection of the elemental specific carbon atomic emission at 193.0 nm. The experimental parameters were systematically investigated. A limit of detection of 0.01 mg L(-1) (as C) was obtained based on a 10 mL sample injection volume, and the precision was better than 6.5% (relative standard deviation, RSD) at 0.1 mg L(-1). The system was successfully applied for TOC analysis of real environmental water samples. The obtained TOC value of 30 test samples agreed well with those by the standard high-temperature combustion coupled nondispersive infrared absorption method. Most importantly, the system showed good capability of in situ continuous monitoring of total organic carbon in environmental water. PMID:24862626

Han, Bingjun; Jiang, Xiaoming; Hou, Xiandeng; Zheng, Chengbin

2014-07-01

197

Temporal stability of solid oxidizers at high temperature and humidity. Memorandum report  

SciTech Connect

Chemical Warfare/Biological Warfare (CW/BW) decontamination operations may rely on aqueous solutions prepared from stored solid oxidizers. Needed are data defining the shipboard storage stability of candidate oxidizers. Therefore, the stability of a series of potential decontaminants has been examined at high temperature (90 + C) and humidity (95 + % R.H.). The loss of oxidizing capacity in aliquots of the oxidizers was followed with time by iodometric titration. Calcium hypochlorite lost over 99% of its oxidizing capacity in less than two days, whereas lithium hypochlorite retained one-third oxidizing capacity for approximately twenty days. Sodium perborate, and sodium persulfate were very hygroscopic and unstable with time. H-48 decomposed in approximately two days, while sodium isocyanurate lost about 80% of its oxidizing capacity in two weeks. The data presented documents severe stability problems of one sort or another with all the materials tested, although overall the sodium isocyanurate appeared to be the more stable candidate undr extreme conditions. In any case, packaging and storage considerations are shown to be important for any potential decontaminant to be stored under environmentally severe conditions.

Pellenbarg, R.E.; Dotson, D.A.

1985-09-30

198

PAH oxidation in aged and spiked soils investigated by column experiments.  

PubMed

Soils of former steel-making or coking plants have been contaminated for decades by PAHs. These soils could be cleaned up by In situ chemical oxidation (ISCO) but the low PAH availability may be a drawback. The objective of the present contribution was to study the efficiency of PAH oxidation in two aged soils compared to a spiked soil in dynamic conditions. Column experiments were performed with two oxidants: hydrogen peroxide used in modified Fenton's reaction and activated persulfate. The oxidant doses were moderate to ensure the feasibility of process upscaling. Besides, the availability of PAHs in these soils was measured by extraction with a cyclodextrin. Our results showed that oxidation was limited: the higher PAH degradation rate was 30% with the aged soils and 55% with the spiked one. PAH availability was a parameter explaining these results but no direct correlation was found between PAH extractability by the cyclodextrin and oxidation efficiency. Other parameters were also involved, such as the organic carbon content, the calcite content and the pH. This study was a first achievement before studying the influence of a number of parameters on the efficiency of PAH oxidation in aged soils. PMID:23290942

Lemaire, Julien; Laurent, Fabien; Leyval, Corinne; Schwartz, Christophe; Buès, Michel; Simonnot, Marie-Odile

2013-04-01

199

In-situ Spectroscopy of Water Oxidation at Ir Oxide Nanocluster Drivenby Visible TiOCr Charge-Transfer Chromophore in Mesoporous Silica  

SciTech Connect

An all-inorganic photocatalytic unit consisting of a binuclear TiOCr charge-transfer chromophore coupled to an Ir oxide nanocluster has been assembled on the pore surface of mesoporous silica AlMCM-41. In situ FT-Raman and EPR spectroscopy of an aqueous suspension of the resulting IrxOy-TiCr-AlMCM-41 powder reveal the formation of superoxide species when exciting the Ti(IV)OCr(III) --> Ti(III)OCr(IV) metal-to-metal charge-transfer chromophore with visible light. Use of H218O confirms that the superoxide species originates from oxidation of water. Photolysis in the absence of persulfate acceptor leads to accumulation of Ti(III) instead. The results are explained by photocatalytic oxidation of water at Ir oxide nanoclusters followed by trapping of the evolving O2 by transient Ti(III) centers to yield superoxide. Given the flexibility to select donor metals with appropriate redox potential, photocatalytic units consisting of a binuclear charge-transfer chromophore coupled to a water oxidation catalyst shown here constitute a step towards thermodynamically efficient visible light water oxidation units.

Frei, Heinz; Han, Hongxian; Frei, Heinz

2008-06-03

200

Metalloporphyrin-sensitized photooxidation of water to oxygen on the surface of colloidal iridium oxides. Photochemical and pulse radiolytic studies  

SciTech Connect

Derivatives of TSPP (tetrakis(4-sulfonatophenyl)porphyrin) were prepared and tested as photosensitizers for oxidation of water to oxygen on the surface of colloidal iridium oxide. Triplet quantum yields, energies, and lifetimes were measured by laser flash photolysis. Rate constants for quenching the porphyrin triplet state with O{sub 2} and with persulfate ions were also determined. The rates of interaction between the porphyrin radical cations and colloidal IrO{sub x} particles were measured by pulse radiolysis for several of the compounds. The one-electron oxidation potentials of the porphyrins, measured by cyclic voltammetry, were varied between 0.7 and 1.4 V vs. NHE by using different metal centers and by substitution on the phenyl rings. Illumination of a porphyrin in the presence of sodium persulfate and an IrO{sub x} colloid resulted in generation of O{sub 2} in a process that was strongly dependent upon pH and upon the nature of the photosensitizer in the same manner as the kinetics determined by pulse radiolysis. The rate of O{sub 2} production under any conditions could be explained on the basis of thermodynamic criteria relating to either of the individual quenching or water oxidation steps. Zn porphyrins (0.9 < E{sub {1/2}} < 1.02 V) effected O{sub 2} production only in alkaline solution, whereas PdTSPP (E{sub {1/2}} = 1.1 V) gave efficient O{sub 2} evolution even in neutral solution. Further increase in E{sub 1/2}, as achieved with InTSPP (E{sub {1/2}} = 1.16 V), lowers the threshold pH for O{sub 2} evolution, and pulse radiolysis experiments confirmed that the radical cation of this porphyrin is the most reactive toward the catalyst, reacting at diffusion-controlled rates even in acidic solutions. However, the rate of O{sub 2} formation with InTSPP was very low due to the inefficient photochemistry arising from the incomplete quenching of this less-reducing porphyrin triplet state by persulfate ions.

Nahor, G.S.; Neta, P. (National Institute of Standards and Technology, Gaithersburg, MD (USA)); Hambright, P. (Howard Univ., Washington, DC (USA)); Thompson, A.N. Jr. (Spelman College, Atlanta, GA (USA)); Harriman, A. (Univ. of Texas, Austin (USA))

1989-08-10

201

Sensitizer-catalyst assemblies for water oxidation.  

PubMed

Two molecular assemblies with one Ru(II)-polypyridine photosensitizer covalently linked to one Ru(II)(bda)L2 catalyst (1) (bda = 2,2'-bipyridine-6,6'-dicarboxylate) and two photosensitizers covalently linked to one catalyst (2) have been prepared using a simple C-C bond as the linkage. In the presence of sodium persulfate as a sacrificial electron acceptor, both of them show high activity for catalytic water oxidation driven by visible light, with a turnover number up to 200 for 2. The linked photocatalysts show a lower initial yield for light driven oxygen evolution but a much better photostability compared to the three component system with separate sensitizer, catalyst and acceptor, leading to a much greater turnover number. Photocatalytic experiments and time-resolved spectroscopy were carried out to probe the mechanism of this catalysis. The linked catalyst in its Ru(II) state rapidly quenches the sensitizer, predominantly by energy transfer. However, a higher stability under photocatalytic condition is shown for the linked sensitizer compared to the three component system, which is attributed to kinetic stabilization by rapid photosensitizer regeneration. Strategies for employment of the sensitizer-catalyst molecules in more efficient photocatalytic systems are discussed. PMID:25700086

Wang, Lei; Mirmohades, Mohammad; Brown, Allison; Duan, Lele; Li, Fusheng; Daniel, Quentin; Lomoth, Reiner; Sun, Licheng; Hammarström, Leif

2015-03-16

202

Solid-liquid separation of oxidized americium from fission product lanthanides  

NASA Astrophysics Data System (ADS)

The separation of americium from the lanthanides and curium is a requirement if transmutation of americium is to be performed in advanced nuclear fuel cycles. Oxidation of Am3+ to AmO2+ or AmO22+ may allow separation of Am from Ln and Cm in one step, since the lanthanides and curium do not have higher oxidation states as accessible. Two possible solid-liquid separation methods have been developed to address this difficult separation. Under acidic conditions using oxone or persulfate, the oxidation and retention of tracer Am in the aqueous phase has been observed with a separation factor of 11 ± 1. Most of these studies have been conducted using 237NpO2(NO3), 233UO2(NO3)2, 238Pu(NO3)4 and 241Am(NO3)3 at radiotracer concentrations. Lanthanides precipitate as the sodium or potassium europium double sulfate salt. Under basic conditions, ozone oxidation of Am(CO3)OH(s) solubilizes Am from a lanthanide carbonate hydroxide solid phase to the aqueous phase as the AmO2(CO3)34-or AmO2(CO3)35- species. For the ozone oxidation of the americium tracer a separation factor of 1.6 ± 0.8 and 47 ± 2 for the oxidation/separation in Na2CO3 and NaHCO3 respectively.

Shehee, T. C.; Martin, L. R.; Nash, K. L.

2010-03-01

203

An exceptionally fast homogeneous carbon-free cobalt-based water oxidation catalyst.  

PubMed

An all-inorganic, oxidatively and thermally stable, homogeneous water oxidation catalyst based on redox-active (vanadate(V)-centered) polyoxometalate ligands, Na10[Co4(H2O)2(VW9O34)2]·35H2O (Na101-V2, sodium salt of the polyanion 1-V2), was synthesized, thoroughly characterized and shown to catalyze water oxidation in dark and visible-light-driven conditions. This synthetic catalyst is exceptionally fast under mild conditions (TOF > 1 × 10(3) s(-1)). Under light-driven conditions using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, 1-V2 exhibits higher selectivity for water oxidation versus bpy ligand oxidation, the final O2 yield by 1-V2 is twice as high as that of using [Co4(H2O)2(PW9O34)2](10-) (1-P2), and the quantum efficiency of O2 formation at 6.0 ?M 1-V2 reaches ?68%. Multiple experimental results (e.g., UV-vis absorption, FT-IR, (51)V NMR, dynamic light scattering, tetra-n-heptylammonium nitrate-toluene extraction, effect of pH, buffer, and buffer concentration, etc.) confirm that the polyanion unit (1-V2) itself is the dominant active catalyst and not Co(2+)(aq) or cobalt oxide. PMID:24937166

Lv, Hongjin; Song, Jie; Geletii, Yurii V; Vickers, James W; Sumliner, Jordan M; Musaev, Djamaladdin G; Kögerler, Paul; Zhuk, Petro F; Bacsa, John; Zhu, Guibo; Hill, Craig L

2014-07-01

204

INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY Nanotechnology 15 (2004) 15241529 PII: S0957-4484(04)83271-9  

E-print Network

persulfate as an oxidant, or alternatively in an enzymatic oxidation by hydrogen peroxide using horseradish persulfate, polyaniline can be grown on DNA templates already immobilized on a surface. Current

Ludwig-Maximilians-Universität, München

205

Destruction of cyanobacterial toxin cylindrospermopsin by hydroxyl radicals and sulfate radicals using UV-254 nm activation of hydrogen peroxide, persulfate and peroxymonosulfate  

EPA Science Inventory

Abstract: With increasing worldwide incidence of toxic cyanobacterial blooms in bodies of water, cylindrospermopsin (CYN) has become a significant concern to public health and water management officials. In this study, the removal of CYN by UV-254 nm-mediated advanced oxidation ...

206

An investigation into the optimum thickness of titanium dioxide thin films synthesized by using atmospheric pressure chemical vapour deposition for use in photocatalytic water oxidation.  

PubMed

Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660?°C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365?nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was ?200?nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation. PMID:20645333

Hyett, Geoffrey; Darr, Jawwad A; Mills, Andrew; Parkin, Ivan P

2010-09-10

207

Studies of nitrile oxide cycloadditions, and the phenolic oxidative coupling of vanillin aldoxime by Geobacillus sp. DDS012 from Italian rye grass silage.  

PubMed

During studies directed towards the discovery of nitrile hydrolysing enzymes from thermophiles, vanillin aldoxime was incubated with the thermophilic organism, Geobacillus sp. DDS012 isolated from Italian rye grass (Lolium multiflorum) silage. The predominant product was a dihydro-dimer, which could only be characterised by LC-MS. This was initially imagined to be the product of cycloaddition of vanillin aldoxime with the corresponding nitrile oxide, but preparation of the supposed adduct and model studies excluded this possibility. The rate constant for the second order dimerisation of 4-O-acetyl vanillin nitrile oxide was measured (1.21 x 10(-4) M(-1) s(-1), 0.413 M, 25 degrees C) and the (13)C-NMR signal for the nitrile oxide carbon was observed (delta(C) 34.4, br. t (1)J(13)C,(14)N circa 50 Hz). Treatment of vanillin aldoxime with potassium persulfate and iron sulfate gave material with the same LC-MS properties as the natural product, which is therefore identified as 5,5'-dehydro-di-(vanillin aldoxime) 1d formed by phenolic oxidative coupling. PMID:18264580

Kelly, David R; Baker, Simon C; King, David S; de Silva, Deepa S; Lord, Gwyn; Taylor, Jason P

2008-02-21

208

The Chimeric Approach Reveals That Differences in the TRPV1 Pore Domain Determine Species-specific Sensitivity to Block of Heat Activation*  

PubMed Central

The capsaicin-, heat-, and proton-activated ion channel TRPV1, a member of the transient receptor potential cation channel family is a polymodal nociceptor. For almost a decade, TRPV1 has been explored by the pharmaceutical industry as a potential target for example for pain conditions. Antagonists which block TRPV1 activation by capsaicin, heat, and protons were developed by a number of pharmaceutical companies. The unexpected finding of hyperthermia as an on-target side effect in clinical studies using polymodal TRPV1 antagonists has prompted companies to search for ways to circumvent hyperthermia, for example by the development of modality-selective antagonists. The significant lack of consistency of the pharmacology of many TRPV1 antagonists across different species has been a further obstacle. JYL-1421 for example was shown to block capsaicin and heat responses in human and monkey TRPV1 while it was largely ineffective in blocking heat responses in rat TRPV1. These findings suggested structural dissimilarities between different TRPV1 species relevant for small compound antagonism for example of heat activation. Using a chimeric approach (human and rat TRPV1) in combination with a novel FLIPR-based heat activation assay and patch-clamp electrophysiology we have identified the pore region as being strongly linked to the observed species differences. We demonstrate that by exchanging the pore domains JYL-1421, which is modality-selective in rat can be made modality-selective in human TRPV1 and vice-versa. PMID:21911503

Papakosta, Marianthi; Dalle, Carine; Haythornthwaite, Alison; Cao, Lishuang; Stevens, Edward B.; Burgess, Gillian; Russell, Rachel; Cox, Peter J.; Phillips, Stephen C.; Grimm, Christian

2011-01-01

209

Degradation of Guar-Based Fracturing Gels: A Study of Oxidative and Enzymatic Breakers  

E-print Network

........................................................... 47 4.3.1.1 Ammonium Persulfate ............................................... 47 4.3.1.2. Magnesium Peroxide ................................................ 55 4.3.1.3. Sodium Bromate... ...................................................................... 74 4.4. Breaker Activity Curves (S-Curves) ...................................................... 79 4.4.1. Ammonium Persulfate ............................................................. 79 4.4.2. Magnesium Peroxide...

Sarwar, Muhammad Usman

2012-02-14

210

The Effect of Al2O3 Addition on the Thermal Diffusivity of Heat Activated Acrylic Resin  

PubMed Central

Aim: This study aimed at investigating the effect of adding 5% to 20% by weight aluminium oxide powder (Al2O3) on thermal diffusivity of heat–polymerized acrylic resin. Material and Methods: Twenty five cylindrical test specimens with an embedded thermocouple were used to determine thermal diffusivity over a physiologic temperature range (0 to 70°C). The specimens were divided into five groups (5 specimens/group) which were coded A to E. Group A was the control group (unmodified acrylic resin specimens). The specimens of the remaining four groups were reinforced with 5%, 10%, 15%, and 20% Al2O3 by weight. Results were analysed by using one–way analysis of variance (ANOVA). Results: Test specimens which belonged to Group E showed the highest mean thermal diffusivity value of 10.7mm2/sec, followed by D (9.09mm2/sec), C (8.49mm2/sec), B(8.28mm2/sec) and A(6.48mm2/sec) groups respectively. Thermal diffusivities of the reinforced acrylic resins were found to be significantly higher than that of the unmodified acrylic resin. Thermal diffusivity was found to increase in proportion to the weight percentage of alumina filler. Conclusion: Al2O3 fillers have potential to provide increased thermal diffusivity. Increasing the heat transfer characteristics of the acrylic resin base material could lead to more patient satisfaction. PMID:24086917

Atla, Jyothi; Manne, Prakash; Gopinadh, A.; Sampath, Anche; Muvva, Suresh Babu; Kishore, Krishna; Sandeep, Chiramana; Chittamsetty, Harika

2013-01-01

211

NF-TiO? photocatalysis of amitrole and atrazine with addition of oxidants under simulated solar light: emerging synergies, degradation intermediates, and reusable attributes.  

PubMed

In order to investigate sustainable alternatives to current water treatment methods, the effect of NF-titania film thickness and subsequent photocatalysis in combination with oxidants was examined under simulated solar light. Such a combination presents a theoretical possibility for a synergistic interaction between the photocatalyst and the oxidant (activation of the oxidant by the catalyst under conditions under which it may not conventionally be activated). To investigate, peroxymonosulfate (PMS) and persulfate (PS) were used as oxidants, and two pesticides, amitrole and atrazine, were used as target contaminants. In the absence of a film, activation of PMS under simulated solar conditions is demonstrated by removal of atrazine, whereas PS provided minimal removal, suggesting inefficient activation. Combining photocatalytic films with PMS and PS manifested synergies for both oxidants. The effect was most pronounced for PS since PMS already underwent significant activation without the photocatalyst. Amitrole degradation results indicated a lack of removal of amitrole by activated PS alone, suggesting that this sulfate radical-based treatment technology may be ineffective for the removal of amitrole. The NF-TiO? films demonstrated reusability under solar light both with and without oxidants. Finally, the degradation intermediates were analyzed, and a new intermediate appeared upon incorporating oxidants into the system. PMID:23811632

Andersen, Joel; Pelaez, Miguel; Guay, Lisa; Zhang, Zhaohong; O'Shea, Kevin; Dionysiou, Dionysios D

2013-09-15

212

Chemical Oxidation  

Microsoft Academic Search

Chemical oxidation is a process involving the transfer of electrons from an oxidizing reagent to the chemical species being\\u000a oxidized. In water and wastewater engineering, chemical oxidation serves the purpose of converting putrescible pollutant substances\\u000a to innocuous or stabilized products. Chemical oxidation processes take place in natural waters and serve as an important mechanism\\u000a in the natural self-purification of surface

Nazih K. Shammas; John Y. Yang; Pao-Chiang Yuan; Yung-Tse Hung

213

Visible Light-Driven Water Oxidation Promoted by Host-Guest Interaction between Photosensitizer and Catalyst with A High Quantum Efficiency.  

PubMed

A highly active supramolecular system for visible light-driven water oxidation was developed with cyclodextrin-modified ruthenium complex as the photosensitizer, phenyl-modified ruthenium complexes as the catalysts, and sodium persulfate as the sacrificial electron acceptor. The catalysts were found to form 1:1 host-guest adducts with the photosensitizer. Stopped-flow measurement revealed the host-guest interaction is essential to facilitate the electron transfer from catalyst to sensitizer. As a result, a remarkable quantum efficiency of 84% was determined under visible light irradiation in neutral aqueous phosphate buffer. This value is nearly 1 order of magnitude higher than that of noninteraction system, indicating that the noncovalent incorporation of sensitizer and catalyst is an appealing approach for efficient conversion of solar energy into fuels. PMID:25799114

Li, Hua; Li, Fei; Zhang, Biaobiao; Zhou, Xu; Yu, Fengshou; Sun, Licheng

2015-04-01

214

Oxides (GCMP)  

NSDL National Science Digital Library

Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". In this problem we will explore the properties of the oxides of a few elements. We will add samples of the oxides to universal indicator solution and learn about the acid-base character of the oxides. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

215

Ethylene Oxide  

Cancer.gov

At room temperature, ethylene oxide is a flammable colorless gas with a sweet odor. It is used primarily to produce other chemicals, including antifreeze. In smaller amounts, ethylene oxide is used as a pesticide and a sterilizing agent. The ability of ethylene oxide to damage DNA makes it an effective sterilizing agent but also accounts for its cancer-causing activity.

216

MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser  

E-print Network

persulfate or chromic acid (Strickland & Parsons 1968) or other oxidizing agents, or irradiation of samples persulfate digestion since Menzel & Corwin (1965) introduced this method. Phosphorus is converted to PO4, replicate seston samples for P undergo a separate, persulfate digestion and are analyzed by colorimetric

217

A direct instrument comparison for measurement of total dissolved nitrogen in seawater  

E-print Network

exercises, samples were also run by the more established persulfate oxidation method. There was fairly good samples in the Homelab exercise. In both cases, the persulfate method values were similar to those. The persulfate method gave slightly higher TDN concentrations for the field samples than the Shimadzu HTC

Seitzinger, Sybil

218

Quantitation of carbon in oil shale process wastewaters: coulometry coupled with ultraviolet-peroxydisulfate and high-temperature oxidation  

SciTech Connect

Wastewaters from the production of synfuels, in particular oil shale retort waters, present several major problems to various instrument configurations designed for carbon analysis. A carbon analyzer was fabricated from commercially available oxidation and detection units. Carbon oxidation occurred in an ultraviolet (UV) photochemical reactor using acid peroxydisulfate; quantitation of the evolved carbon dioxide was accomplished with an automatic coulometric titrator. This new design eliminated the problems of (1) instrument downtime caused by fouling of high-temperature combustion catalysts and corrosion of furnace combustion tubes, (2) limited linear dynamic range and upper detection limit (namely, infrared detection), and (3) frequent detector calibration (namely, infrared and flame ionization detection). The UV-persulfate/coulometric titration carbon analyzer was compared statistically with a high-temperature combustion system that is suitable for use with an ASTM method on the basis of (1) the accuracy and precision of recovery of total dissolved carbon (TDC) and dissolved organic carbon (DOC) for nitrogen heterocycles, which were of primary interest because of their preponderance in oil shale process waters and their reported resistance to certain oxidation methods, and (2) the precision of TDC and DOC determinations for nine oil shale process wastewaters. Several qualitative considerations are discussed for both analyzers, including ease of operation, instrument downtime, and maintenance costs. 35 references, 7 figures, 5 tables.

Langlois, G.W.; Jones, B.M.; Sakaji, R.H.; Daughton, C.G.

1984-07-01

219

Identification and cleavage of breakable single bonds by selective oxidation, reduction, and hydrolysis. Annual report, October 1, 1980-September 30, 1981  

SciTech Connect

The objective of this project is to determine the structure of bituminous coal by determining the proportions of the various kinds of connecting bonds and how they can best be broken. Results obtained during the past quarter are presented for the following tasks: (1) extractions and fractionations of coal products which covers pyridine extraction, fractionation of TIPS fractions, EDA extraction of Illinois No. 6 coal and swelling ratios of coal samples; (2) experiments on breakable single bonds which cover reactions of ethylenediamine and model ethers, reaction of pyridine-extracted coal with Me/sub 3/SiI, Baeyer-Villiger oxidations, reaction to diphenylmethane with 15% HNO/sub 3/, cleavage of TIPS with ZnI/sub 2/, and cleavage of black acids; and (3) oxygen oxidation No. 18. Some of the highlights of these studies are: (1) some model ethers are not cleaved by EDA under extraction conditions; (2) oxidation of diaryl ketones with m-chloroperbenzoic acid and saponification of the resulting esters in promising for identifying ketones, (3) treatment of a black acid with pyridine hydroiodide reduced the acid's molecular weight and increased its solubility in pyridine, but treatment with ZnI/sub 2/ was ineffective; (4) in comparison with 0.1 M K/sub 2/S/sub 2/O/sub 8/, 0.01 M persulfate is relatively ineffective in accelerating oxidation of BnNH/sub 2/-extracted coal in water suspension. 2 figures, 3 tables.

Hirschon, A.S.; Zevely, J.; Mayo, F.R.

1981-11-12

220

Feasibility study on an oxidant-injected permeable reactive barrier to treat BTEX contamination: adsorptive and catalytic characteristics of waste-reclaimed adsorbent.  

PubMed

The adsorptive and catalytic characteristics of waste-reclaimed adsorbent (WR), which is a calcined mixture of bottom-ash and dredged-soil, was investigated for its application to treating BTEX contamination. BTEX adsorption in WR was 54%, 64%, 62%, and 65%, respectively, for a 72 h reaction time. Moreover, the catalytic characteristics of WR were observed when three types of oxidation systems (i.e., H(2)O(2), persulfate (PS), and H(2)O(2)/Fe(III)/oxalate) were tested, and these catalytic roles of WR could be due to iron oxide on its surface. In PS/WR system, large amounts of metal ions from WR were released because of large drops of solution pH, and the surface area of WR was also greatly reduced. Moreover, the BTEX that was removed per consumed oxidant (?C(rem)/?Ox) increased with increasing PS. In H(2)O(2)/Fe(III)/oxalate with WR system, the highest BTEX degradation rate constants (k(deg)) were calculated as 0.338, 0.365, 0.500 and 0.716 h(-1), respectively, when 500 mM of H(2)O(2) was used, and the sorbed BTEX on the surface of WR was also degraded, which suggests the regeneration of WR. Therefore, the oxidant-injected permeable reactive barrier filled in WR could be an alternative to treating BTEX with both adsorption and catalytic degradation. PMID:21514045

Do, Si-Hyun; Kwon, Yong-Jae; Kong, Sung-Ho

2011-07-15

221

Methanol oxidation on semiconducting oxides  

Microsoft Academic Search

Correlations between reaction rates and selectivities vs. Egap (eV) of the semiconducting oxides Co3O4, CuO, NiO, Cr2O3, ?-Fe2O3, TiO2 and MoO3 were obtained for the catalytic air oxidation of methanol at 573 K. Higher and lower selectivities to formaldehyde for Egap>2 n-type, and Egap >2 p-type semiconducting oxides, are observed, respectively.

J. Estellé; J. E. Sueiras

1993-01-01

222

Nitric oxide  

Microsoft Academic Search

Nitric oxide (NO) is a gas with diverse biological activities produced from arginine by NO synthases. It is capable of interacting with a number of molecules, most notably superoxide, forming peroxynitrite, which, in turn, can mediate bactericidal or cytotoxic reactions. Nitric oxide also mediates smooth muscle relaxation, neurotransmission, and modulation of inflammation in a number of organ systems and pathophysiologic

Richard A. Robbins; Matthew B. Grisham

1997-01-01

223

Design, synthesis, and characterization of materials for controlled line deposition, environmental remediation, and doping of porous manganese oxide material  

NASA Astrophysics Data System (ADS)

This thesis covers three topics: (1) coatings formed from sol-gel phases, (2) environmental remediation, and (3) doping of a porous manganese oxide. Synthesis, characterization, and application were investigated for each topic. Line-formations were formed spontaneously by self-assembly from vanadium sol-gels and other metal containing solutions on glass substrates. The solutions were prepared by the dissolution of metal oxide or salt in water. A more straightforward method is proposed than used in previous work. Analyses using optical microscopy, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and infrared spectroscopy showed discreet lines whose deposition could be controlled by varying the concentration. A mechanism was developed from the observed results. Microwave heating, the addition of graphite rods, and oxidants, can enhance HCB remediation from soil. To achieve remediation, a TeflonRTM vessel open to the atmosphere along with an oxidant, potassium persulfate (PerS) or potassium hydroxide, along with uncoated or aluminum oxide coated, graphite rods were heated in a research grade microwave oven. Microwave heating was used to decrease the heating time, and graphite rods were used to increase the absorption of the microwave energy by providing thermal centers. The results showed that the percent HCB removed was increased by adding graphite rods and oxidants. Tungsten, silver, and sulfur were investigated as doping agents for K--OMS-2. The synthesis of these materials was carried out with a reflux method. The doping of K--OMS-2 led to changes in the properties of a tungsten doped K--OMS-2 had an increased resistivity, the silver doped material showed improved epoxidation of trans-stilbene, and the addition of sulfur produced a paper-like material. Rietveld refinement of the tungsten doped K--OMS-2 showed that the tungsten was doped into the framework.

Calvert, Craig A.

224

Treating organic pollutants in urban runoff using slow-release oxidants and storm pipes: A field investigation  

NASA Astrophysics Data System (ADS)

Non-point source (NPS) contamination is a major concern for urban aquatic environments. This study tested the efficacy of using slow-release oxidants emplaced in storm pipes for treating organic pollutants in urban storm runoff through proof-of-concept laboratory tests and a field demonstration test in Athens, OH. Release rates of slow-release persulfate (SR-PS), slow-release hydrogen pyroxide (SR-HP), and slow-release iron (SR-Fe) were estimated through column tests. Runoff samples were collected at a storm pipe discharge point in the study area for 3 storm events having different prior drought periods to establish baseline concentrations of organic pollutants. Samples were analyzed for Methyl-tert-butyl-ether (MTBE), Naphthalene, and total organic carbon contents. The proof-of-concept flow-through test demonstrated that up 90% of pollutants can be removed by the SR-PS/Fe within 20 minutes of reaction time. The SR-PS/HP/Fe forms are emplaced in several storm drains where the pollutants would have ~15 minutes of reaction with the oxidants released from the slow-release forms. Preliminary results suggest that the SR-PS/HP/Fe forms installed in the storm pipes can reduce NPS pollutants in the urban storm runoff in a sustainable manner.

Eyerdom, T. J.; Lee, E.; Kim, Y.

2013-12-01

225

Improved method for the determination of nonpurgeable suspended organic carbon in natural water by silver filter filtration, wet chemical oxidation, and infrared spectrometry  

USGS Publications Warehouse

Precision and accuracy are reported for the first time for the analysis of nonpurgeable suspended organic carbon by silver membrane filtration followed by wet chemical oxidation. A water sample is pressure filtered through a 0.45-??m-pore-size, 47-mm-diameter silver membrane filter. The silver membrane filter then is cut into ribbons and placed in a flame-sealable glass ampule. The organic material trapped on the membrane filter strips is acidified, purged with oxygen to remove inorganic carbonates and volatile organic compounds, and oxidized to carbon dioxide (CO2) using phosphoric acid and potassium persulfate in the sealed glass ampule. The resulting CO2 is measured by a nondispersive infrared CO2 detector. The amount of CO2 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the environmental water sample. The quantitation and method detection limit for routine analysis is 0.2 mg/L. The average percent recovery in five representative matrices was 97 ?? 11%. The errors associated with sampling and sample preparation of nonpurgeable suspended organic carbon are also described.Precision and accuracy are reported for the first time for the analysis of nonpurgeable suspended organic carbon by silver membrane filtration followed by wet chemical oxidation. A water sample is pressure filtered through a 0.45-??m-pore-size, 47-mm-diameter silver membrane filter. The silver membrane filter then is cut into ribbons and placed in a flame-sealable glass ampule. The organic material trapped on the membrane filter strips is acidified, purged with oxygen to remove inorganic carbonates and volatile organic compounds, and oxidized to carbon dioxide (CO2) using phosphoric acid and potassium persulfate in the sealed glass ampule. The resulting CO2 is measured by a nondispersive infrared CO2 detector. The amount of CO2 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the environmental water sample. The quantitation and method detection limit for routine analysis is 0.2 mg/L. The average percent recovery in five representative matrices was 97??11%. The errors associated with sampling and sample preparation of nonpurgeable suspended organic carbon are also described.

Burkhardt, M.R.; Brenton, R.W.; Kammer, J.A.; Jha, V.K.; O'Mara-Lopez, P. G.; Woodworth, M.T.

1999-01-01

226

Magnesium Oxide  

MedlinePLUS

... used for different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative for short-term, rapid emptying of ...

227

Development of Alkaline Oxidative Dissolution Methods for Chromium (III) Compounds Present in Hanford Site Tank Sludges  

SciTech Connect

The high-level radioactive waste sludge in the underground storage tanks at the Hanford Site contains various chromium solid phases. Dissolution and removal of chromium from tank waste sludges is desirable prior to high-level waste vitrification because increased volume is required to incorporate the residual chromium. Unfortunately, dissolution of chromium from the sludge to form Cr(OH){sub 4}{sup -} through treatment with heated NaOH solution (also used to dissolve aluminum phases and metathesize phosphates to sodium salts) generally has been unsuccessful in tests with both simulated and genuine Hanford waste sludges. Oxidative dissolution of the Cr(III) compounds to form soluble chromate has been proposed as an alternative chromium solid phase dissolution method and results of limited prior testing have been reported. The present systematic tests investigated oxygen gas, hydrogen peroxide, and sodium persulfate oxidants to dissolve Cr(III) under alkaline conditions to form soluble chromate. Permanganate and ozone also were considered for testing but were thought to be of secondary interest because of the insoluble residue (MnO{sub 2} from permanganate) and complex equipment (necessary to generate ozone) implicit with use of these reagents. The oxygen and hydrogen peroxide reagents leave no condensable residue and sodium persulfate only leaves soluble sodium sulfate. Crystalline Cr(OH){sub 3}, various hydrothermally aged amorphous Cr(III) oxide hydrates, mixed Fe(III)/Cr(III) oxide hydrates, and nickel and iron Cr(III) spinels, all of which have been identified or are likely constituents in Hanford tank wastes, were prepared and characterized for the dissolution tests. The effects of reagent and hydroxide concentrations, reaction temperature, and transition metal catalysts on reaction progress were investigated for each reagent as functions of reaction time. Reaction progress was measured by monitoring chromate concentration. Oxidation of chromium compounds by dissolved oxygen was found to increase linearly with oxygen partial pressure and NaOH concentration. The rate also increased with temperature at low activation energy, 26-36 kJ/mol, reflecting the opposing influences of decreasing oxygen volubility and increasing underlying chemical reaction rate. The reaction apparently proceeds by way of dissolved Cr(III) species, is catalyzed by Ni(II), and is slower for the hydrothermally aged materials. Dissolution rates ranged from about 7 x 10{sup -5} to 2.4 x 10{sup -4} moles Cr(III)/liter-hour in 80 C, 3-M NaOH with one atmosphere pure oxygen for the various Cr(III) compounds tested. These low dissolution rates commend the use of oxygen reagent to waste tank processing where extended residence times maybe practical. Oxidative dissolution of Cr(III) compounds by hydrogen peroxide was hampered in the presence of greater than 0.5 g Fe(III)/liter and other catalysts for H{sub 2}O{sub 2} decomposition and was less effective for materials that had undergone prolonged aging at high temperatures. Leaching was optimized at low excess NaOH and high temperatures (activation energy of {approx}82 kJ/mol). To prevent excessive loss of H{sub 2}O{sub 2} to catalytic decomposition, the peroxide reagent must be added slowly and with intense stirring. Treatment of waste solids with H{sub 2}O{sub 2} may only be attractive for freshly formed Cr(III) hydroxides [formed, for example, by alkaline metathesis of Cr(III)-bearing sludges] in the absence of decomposition catalysts such as Fe(III).

Delegard, Calvin H.; Krot, N N.; Shilov, V P.; Fedoseev, A M.; Budantseva, N A.; Nikonov, M V.; Yusov, A B.; Garnov, A Y.; Charushnikova, I A.; Perminov, V P.; Astafurova, L N.; Lapitskaya, T S.; Makarenkov, V I.

1999-07-02

228

Visible-light-induced water oxidation mediated by a mononuclear-cobalt(II)-substituted silicotungstate.  

PubMed

A mononuclear-cobalt(II)-substituted silicotungstate, K10[Co(H2O)2(?-SiW10O35)2]?23?H2O (POM-1), has been evaluated as a light-driven water-oxidation catalyst. With in situ photogenerated [Ru(bpy)3](3+) (bpy=2,2'-bipyridine) as the oxidant, quite high catalytic turnover number (TON; 313), turnover frequency (TOF; 3.2?s(-1)), and quantum yield (?(QY); 27%) for oxygen evolution at pH?9.0 were acquired. Comparison experiments with its structural analogues, namely [Ni(H2O)2(?-SiW10O35)2](10-) (POM-2) and [Mn(H2O)2(?-SiW10O35)2](10-) (POM-3), gave the conclusion that the cobalt center in POM-1 is the active site. The hydrolytic stability of the title polyoxometalate (POM) was confirmed by extensive experiments, including UV/Vis spectroscopy, linear sweep voltammetry (LSV), and cathodic adsorption stripping analysis (CASA). As the [Ru(bpy)3](2+)/visible light/sodium persulfate system was introduced, a POM-photosensitizer complex formed within minutes before visible-light irradiation. It was demonstrated that this complex functioned as the active species, which remained intact after the oxygen-evolution reaction. Multiple experimental parameters were investigated and the catalytic activity was also compared with the well-studied POM-based water-oxidation catalysts (i.e., [Co4(H2O)2(?-PW9O34)2](10-) (Co4-POM) and [Co(III)Co(II)(H2O)W11O39](7-) (Co2-POM)) under optimum conditions. PMID:25145473

Xiang, Rui; Ding, Yong; Zhao, Junwei

2014-11-01

229

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

SciTech Connect

Western Research Institute in conjunction with Sierra West Consultants, Inc., Tetra Tech, Inc., and the U.S. Department of Energy conducted laboratory and field studies to test different approaches to enhance degradation of hydrocarbons and associated contaminants. WRI in conjunction with Sierra West Consultants, Inc., conducted a laboratory and field study for using ozone to treat a site contaminated with MTBE and other hydrocarbons. Results from this study demonstrate that a TOD test can be used to resolve the O{sub 3} dosage problem by establishing a site-specific benchmark dosage for field ozone applications. The follow-up testing of the laboratory samples provided indications that intrinsic biodegradation could be stimulated by adding oxygen. Laboratory studies also suggests that O3 dosage in the full-scale field implementation could be dialed lower than stoichiometrically designed to eliminate the formation of Cr(VI). WRI conducted a study involving a series of different ISCO oxidant applications to diesel-contaminated soil and determined the effects on enhancing biodegradation to degrade the residual hydrocarbons. Soils treated with permanganate followed by nutrients and with persulfate followed by nutrients resulted in the largest decrease in TPH. The possible intermediates and conditions formed from NOM and TPH oxidation by permanganate and activated persulfate favors microbial TPH degrading activity. A 'passive-oxidation' method using microbial fuel cell (MFC) technology was conducted by WRI in conjunction with Tetra Tech, Inc., to degrade MTBE in groundwater. These experiments have demonstrated that a working MFC (i.e., one generating power) could be established in the laboratory using contaminated site water or buffered media inoculated with site water and spiked with MTBE, benzene, or toluene. Electrochemical methods were studied by WRI with goal of utilizing low voltage and amperage electrical sources for 'geo-oxidation' of organic contaminants. The results from a study with TCE contaminated-clay indicate that electrochemically inducing reductive dechlorination of TCE in a saturated matrix may offer an effective and viable alternative to remediation TCE and other contaminants with potential of being reduced. Another study focused on steel wool oxidation to electrochemically increase population of hydrocarbon-degrading denitrifying bacteria. Significantly larger denitrifying activity was observed in the cathode chamber of a treatment unit setup like an MFC with steel wool as the anode. This enhanced nitrate reduction could be due to direct electron utilization by denitrifying bacteria on the cathode, thereby stimulating microbial denitrification or a combination of electron transfer directly to NO{sub 3}{sup -} and electron transfer to nitrate reducing bacteria, which may serve as a type of bio-catalyst on the cathode for nitrate reduction. Overall, the studies conducted under Task 72 demonstrated different innovative methods to enhance petroleum hydrocarbon degradation and associated contaminants.

Paul Fallgren

2009-03-06

230

Oxidation catalyst  

DOEpatents

The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

Ceyer, Sylvia T. (Cambridge, MA); Lahr, David L. (Cambridge, MA)

2010-11-09

231

NITROGEN OXIDES  

EPA Science Inventory

This report is a review of current knowledge of the environmental health basis for control of manmade sources of nitrogen oxide emissions. The literature review covered the period through 1974. The principal subject areas considered in the report include: sources and control of a...

232

Oxidation of dodecane on transition metal oxides  

NASA Astrophysics Data System (ADS)

The catalytic oxidation of dodecane on individual and mixed vanadium and molybdenum oxides is studied. Products of the oxidation of alkane are studied qualitatively and quantitatively. The activities of the samples of the catalysts with various ratios of vanadium and molybdenum oxides are compared. One possible scheme for the activation of reagents on a catalyst is given.

Vishnetskaya, M. V.; Vakhrushin, P. A.

2012-11-01

233

Oxidative DNA modifications  

Microsoft Academic Search

Oxidative DNA modifications are frequent in mammalian DNA and have been suggested an important mechanism in carcinogenesis, diabetes and ageing. The foundations for this suggestion are:Evidence for the importance of oxidative DNA modifications in cancer development is: high levels of oxidative lesions in cancer tissue; highly conserved and specific DNA repair systems targeting oxidative lesions; high levels of oxidative DNA

Henrik E. Poulsen

2005-01-01

234

Oxide nanoelectronics  

NASA Astrophysics Data System (ADS)

This thesis describes research performed on two types of complex oxide heterostructures. The first consists of ultrathin LaAlO 3 films grown on SrTiO3 substrates. At the interface between these two insulating oxides, a quasi-two dimensional electron gas may form under proper conditions. This interface has remarkable properties such as interfacial superconductivity, interfacial magnetism and a hysteretic voltage-controlled metal-insulator transition. An Atomic Force Microscope (AFM) lithography technique is developed which is capable of switching reversibly at room temperature this metal-insulator transition with nanometer scale spatial resolution. Based on this technique, conducting nanowires as thin as 2 nm and nanodots array with density up to 1014 inch-2 were written, probed and erased. Sketch-defined field effect transistors (SketchFET) with channel lengths as short as 2 nm were fabricated. These structures were characterized over a temperature range 15 K-300 K, revealing a complex energy landscape. Magnetotransport measurements performed at temperatures at and below 1 K reveal a variety of intriguing quantum phenomena, including integer and fractional quantum Hall states. The second material system consists of thin films of SrTiO3 grown directly on silicon. Although SrTiO3 is not ferroelectric at any temperature in bulk form, when strained to the silicon lattice it can become ferroelectric at and above room temperature. Temperature-dependent piezo force microscopy was performed to verify that those strain engineered films with certain thickness are indeed ferroelectric. Ultrafast optical experiments were carried out to measure lattice dynamics in these strained films. A coherent acoustic phonon mode was observed and studied as a function of film thickness and laser polarization. Using SrTiO3 grown on silicon-on-insulator structures, ferroelectric field effect transistors (FeFET) were fabricated and characterized at room temperature.

Cen, Cheng

235

Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation.  

PubMed

A specific methodology based on nitric acid hydrothermal oxidation was used to control the surface chemistry of multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes (CNTs) with different lengths, and this methodology was adapted to the use of sulphuric acid containing ammonium persulfate as an oxidizing agent. The amount of oxygen-containing surface groups depends on the number and length of the graphene layers of the CNTs, thicker and shorter CNTs having more reactive sites for surface functionalization. In particular, the oxidation of MWCNTs was more pronounced than that of short SWCNTs and less surface groups were introduced into long SWCNTs, regardless of the acid used at any fixed concentration. It was also possible to tailor the surface chemistry of both SWCNTs and MWCNTs by using the adopted methodologies, and the amount of both oxygen- and sulphur-containing functional groups was correlated with the concentration of each oxidizing agent used. Mathematical functions that allow precise control of the amount and type of the surface groups introduced into carbon nanotubes were obtained. Buckypapers were also prepared over a polytetrafluoroethylene commercial membrane. These membranes were tested in direct contact membrane distillation and, under salinity conditions, the membrane prepared using oxidized MWCNTs (instead of SWCNTs) was the most efficient, the permeate flux of the commercial membrane significantly increasing in the presence of these CNTs, while completely rejecting chloride ions. In addition, the permeate flux was precisely correlated with the amount of oxygenated functional surface groups (as well as with the pH of point of zero charge) of the oxidized MWCNTs. PMID:24821484

Morales-Torres, Sergio; Silva, Tânia L S; Pastrana-Martínez, Luisa M; Brandão, Ana T S C; Figueiredo, José L; Silva, Adrián M T

2014-06-28

236

Asphalt Oxidation Kinetics and Pavement Oxidation Modeling  

E-print Network

Most paved roads in the United States are surfaced with asphalt. These asphalt pavements suffer from fatigue cracking and thermal cracking, aggravated by the oxidation and hardening of asphalt. This negative impact of asphalt oxidation on pavement...

Jin, Xin

2012-07-16

237

The inventory, seasonality and stoichiometry of the major phosphorus pools in the Sargasso Sea  

E-print Network

of the UV method and the persulfate method of Koroleff (1983), Ridal and Moore (1990) found that the standard protocols of these methods did not completely convert the DOP from marine samples and they recommended a 39 combination of both methods... for measuring TDP. Ormaza-Gonzalez and Statham (1996) compared five TDP methods including the UV and persulfate methods, along with a combustion method, a nitrate oxidation method and an alkaline persulfate method. Their recommended method was the nitrate...

Case, Darin A

2001-01-01

238

Fluorescent Graphene Oxide via Polymer Grafting: An Efficient Nanocarrier for Both Hydrophilic and Hydrophobic Drugs.  

PubMed

Functionalized graphene-based drug delivery vehicles have conquered a significant position because functionalization improves its biocompatibility and stability in cell medium, leaving sufficient graphitic basal plane for drug loading through ?-? stacking. In this study, poly(N-isopropylacrylamide) (PNIPAM) is covalently grafted from the surface of graphene oxide (GO) via a facile, eco-friendly and an easy procedure of free radical polymerization (FRP) using ammonium persulfate initiator. Various spectroscopic and microscopic studies confirm the successful grafting of PNIPAM from GO surface. PNIPAM-grafted GO (GPNM) exhibits enhanced thermal stability, improved dispersibility both in aqueous and cell medium, and better biocompatibility and cell viability compared to GO. Interestingly, GPNM displays an exciting fluorescence property in aqueous medium, which is a hike of intensity at 36 °C due to the lower critical solution temperature (LCST) of PNIPAM chains (32 °C). Moreover both hydrophilic (doxorubicin (DOX)) and hydrophobic (indomethacin (IMC)) drugs loaded on the surface of GPNM hybrid exhibits its efficacy as an efficient carrier for both types of drugs. Cellular uptakes of free DOX and DOX-loaded GPNM (GPNM-DOX) are evidenced both from optical and fluorescence imaging of live cells, and the efficiency of drug is significantly improved in the loaded system. The release of DOX from GPNM-DOX was achieved at pH 4, relevant to the environment of cancer cells. The pH-triggered release of hydrophobic drug was also studied using UV-vis spectroscopy via alginate encapsulation, showing a great enhancement at pH = 7.4. The IMC is also found to be released by human serum albumin using dialysis technique. The GPNM nanomaterial shows the property of simultaneous loading of DOX and IMC as well as pH-triggered simultaneous release of both of the drugs. PMID:25612470

Kundu, Aniruddha; Nandi, Sudipta; Das, Pradip; Nandi, Arun K

2015-02-18

239

Oxidation resistance of silicon ceramics  

NASA Technical Reports Server (NTRS)

Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

Yasutoshi, H.; Hirota, K.

1984-01-01

240

Thermally exfoliated graphite oxide  

NASA Technical Reports Server (NTRS)

A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

2011-01-01

241

The Enzymatic Oxidation of Graphene Oxide  

PubMed Central

Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

Kotchey, Gregg P.; Allen, Brett L.; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A.; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Kagan, Valerian E.; Star, Alexander

2011-01-01

242

Zinc oxide hexagram whiskers  

NASA Astrophysics Data System (ADS)

Through vapor-phase transport method, zinc oxide hexagram whiskers with uniform size and morphology were fabricated by heating a mixture source of zinc oxide, indium oxide, and graphite powders in air. Each whisker presented a hexagonal disk core closed by six equivalent surfaces of {101¯0} and was surrounded by side nanorods grown along the diagonal of the core disk in the 6-symmetric directions of ±[112¯0], ±[21¯1¯0], and ±[12¯10]. Based on the vapor-liquid-solid mechanism, the growth process of the zinc oxide hexagrams were discussed by considering the thermal dynamic properties of zinc oxide and indium oxide.

Xu, C. X.; Sun, X. W.; Dong, Z. L.; Zhu, G. P.; Cui, Y. P.

2006-02-01

243

Oxidative Stress, Nitric Oxide, and Diabetes  

PubMed Central

In the recent decades, oxidative stress has become focus of interest in most biomedical disciplines and many types of clinical research. Increasing evidence from research on several diseases show that oxidative stress is associated with the pathogenesis of diabetes, obesity, cancer, ageing, inflammation, neurodegenerative disorders, hypertension, apoptosis, cardiovascular diseases, and heart failure. Based on this research, the emerging concept is that oxidative stress is the “final common pathway”, through which risk factors of several diseases exert their deleterious effects. Oxidative stress causes a complex dysregulation of cell metabolism and cell-cell homeostasis. In this review, we discuss the role of oxidative stress in the pathogenesis of insulin resistance and beta-cell dysfunction. These are the two most relevant mechanisms in the pathophysiology of type 2 diabetes, and in the pathogenesis of diabetic vascular complications, the leading cause of death in diabetic patients. PMID:20703435

Pitocco, Dario; Zaccardi, Francesco; Di Stasio, Enrico; Romitelli, Federica; Santini, Stefano A.; Zuppi, Cecilia; Ghirlanda, Giovanni

2010-01-01

244

Bridged graphite oxide materials  

NASA Technical Reports Server (NTRS)

Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

2010-01-01

245

Interfacial Bonding Stabilizes Rhodium and Rhodium Oxide Nanoparticles on Layered Nb Oxide and Ta Oxide Supports  

E-print Network

Interfacial Bonding Stabilizes Rhodium and Rhodium Oxide Nanoparticles on Layered Nb Oxide and Ta temperatures. Rhodium oxide and rhodium metal nanoparticles on niobate and tantalate supports are anomalously

246

Diesel Oxidation Catalysts  

Microsoft Academic Search

The diesel oxidation catalyst (DOC) has been part of diesel exhaust systems since regulations were introduced to limit the amount of harmful emissions released to the environment from diesel engines. The DOC primary functions are oxidation of CO, unburned hydrocarbons, and NO, while active hydrocarbon oxidation can also be used to generate exotherms required for downstream components. This review will

April Russell; William S. Epling

2011-01-01

247

Studies in zirconium oxidation  

NASA Technical Reports Server (NTRS)

Study provides insight into the oxidation mechanism of zirconium by combining electrical measurements with oxidation data. The measurement of electrical potential across growing scale on zirconium and the determination of conventional weight-change oxidation data were carried out at 550, 700, and 800 degrees C.

Draley, J. E.; Drunen, C. J.; Levitan, J.

1968-01-01

248

Solid Oxide Fuel Cell  

NSDL National Science Digital Library

This page is an introduction to the Solid Oxide fuel cell. It uses flash software to explain in greater detail what the Solid Oxide fuel cell consists of and how it works. The website has an introductory animation which is followed by more in depth description of the solid oxide fuel cell.

249

Zinc oxide hexagram whiskers  

Microsoft Academic Search

Through vapor-phase transport method, zinc oxide hexagram whiskers with uniform size and morphology were fabricated by heating a mixture source of zinc oxide, indium oxide, and graphite powders in air. Each whisker presented a hexagonal disk core closed by six equivalent surfaces of {1010} and was surrounded by side nanorods grown along the diagonal of the core disk in the

C. X. Xu; X. W. Sun; Z. L. Dong; G. P. Zhu; Y. P. Cui

2006-01-01

250

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2. Results from X-ray Absorption September 23, 2010. Accepted October 1, 2010. Arsenite (AsIII ) oxidation by manganese oxides (Mn Manganese-oxides (Mn-oxides) commonly occur as fine- grained particles or coatings in terrestrial

Sparks, Donald L.

251

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1.  

E-print Network

Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide 1. Stirred-Flow Experiments B R A N D O September 23, 2010. Accepted October 1, 2010. Manganese-oxides (Mn-oxides) are quite reactive, with respect of studying reaction mechanisms over time. Introduction Manganese-oxide minerals (Mn-oxides) are powerful

Sparks, Donald L.

252

Rhodium oxides in unusual oxidation states  

NASA Astrophysics Data System (ADS)

Mixed valence RhIII/RhIV oxides have been proposed as a promising class of candidate compounds for superconductivity. Unfortunately, it is difficult to stabilize rhodates with a formal oxidation state approaching RhIV, as other techniques used for the synthesis of rhodium. oxides favor the most commonly observed formal oxidation state, RhIII. One technique which has been used to stabilize metal oxides in high formal oxidation states is crystallization from molten hydroxides. This thesis explores the use of molten hydroxides to enhance the reactivity of rhodium oxides in order to synthesize rhodates with high formal oxidation states. K0.5RhO2, Rb0.2RhO2, and CsxRhO2 were synthesized from pure alkali metal hydroxides. All crystallized with a previously unobserved polytype in the alkali metal rhodate system. Due to the low activity of dissolved oxygen species in LiOH and NaOH, LiRhO2 and NaRhO2 cannot be crystallized. The formal oxidation state of rhodium in AxRhO2 (A = K, Rb, Cs) is a function of the alkali metal hydroxide used to synthesize these oxides. These materials exhibit remarkable stability for layered metal oxides containing the heavier alkali metals, but all phases are susceptible to intercalation by water. The synthesis, structural characterization, magnetic susceptibility, and reactivity of these oxides are reported. Sr2RhO4 and a new rhodate were crystallized from a KOH-Sr(OH)2 flux. The synthesis and characterization of these materials is reported. Efforts to substitute platinum for rhodium in Sr 2RhO4 are also discussed. Mixed alkali metal-alkaline earth metal hydroxide fluxes were used to crystallize LiSr3RhO6, and NaSr3RhO 6. The synthesis of LiSr3RhO6 and NaSr3RhO 6 represents the first example of the stabilization of a rhodium oxide with a formal oxidation state approaching RhV. X-ray diffraction, electron beam microprobe analysis, thermogravimetric analysis, potentiometric titrations, X-ray photoelectron spectroscopy, and magnetic susceptibility measurements were used to verify this formal oxidation state. The synthetic methodology developed for the synthesis of rhodium oxides in high formal oxidation states has also been applied to the synthesis of other members of the platinum group metals. LiSr3RuO6, NaSr3RuO6, LiSr3IrO6, NaSr 3IrO6, LiSr3PtO6,and NaSr3PtO 6 were crystallized from mixed alkali metal-alkaline earth metal hydroxide fluxes. The synthesis and structural characterization of these materials is presented.

Reisner, Barbara Alice

253

Partial oxidation catalyst  

DOEpatents

A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

Krumpelt, Michael (Naperville, IL); Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Doshi, Rajiv (Downers Grove, IL)

2000-01-01

254

Numerical simulation of in-situ chemical oxidation (ISCO) and biodegradation of petroleum hydrocarbons using a coupled model for bio-geochemical reactive transport  

NASA Astrophysics Data System (ADS)

Petroleum hydrocarbons (PHCs) are a major source of groundwater contamination, being a worldwide and well-known problem. Formed by a complex mixture of hundreds of organic compounds (including BTEX - benzene, toluene, ethylbenzene and xylenes), many of which are toxic and persistent in the subsurface and are capable of creating a serious risk to human health. Several remediation technologies can be used to clean-up PHC contamination. In-situ chemical oxidation (ISCO) and intrinsic bioremediation (IBR) are two promising techniques that can be applied in this case. However, the interaction of these processes with the background aquifer geochemistry and the design of an efficient treatment presents a challenge. Here we show the development and application of BIONAPL/Phreeqc, a modeling tool capable of simulating groundwater flow, contaminant transport with coupled biological and geochemical processes in porous or fractured porous media. BIONAPL/Phreeqc is based on the well-tested BIONAPL/3D model, using a powerful finite element simulation engine, capable of simulating non-aqueous phase liquid (NAPL) dissolution, density-dependent advective-dispersive transport, and solving the geochemical and kinetic processes with the library Phreeqc. To validate the model, we compared BIONAPL/Phreeqc with results from the literature for different biodegradation processes and different geometries, with good agreement. We then used the model to simulate the behavior of sodium persulfate (NaS2O8) as an oxidant for BTEX degradation, coupled with sequential biodegradation in a 2D case and to evaluate the effect of inorganic geochemistry reactions. The results show the advantages of a treatment train remediation scheme based on ISCO and IBR. The numerical performance and stability of the integrated BIONAPL/Phreeqc model was also verified.

Marin, I. S.; Molson, J. W.

2013-05-01

255

Structures of Selenomonas ruminantium Phytase in Complex with Persulfated Phytate  

Microsoft Academic Search

Various inositide phosphatases participate in the regulation of inositol polyphosphate signaling molecules. Plant phytases are phosphatases that hydrolyze phytate to less-phosphorylated myo-inositol derivatives and phosphate. The phytase from Selenomonas ruminantium shares no sequence homology with other microbial phytases. Its crystal structure revealed a phytase fold of the dual-specificity phosphatase type. The active site is located near a conserved cysteine-containing (Cys241)

Hsing-Mao Chu; Rey-Ting Guo; Ting-Wan Lin; Chia-Cheng Chou; Hui-Lin Shr; Hui-Lin Lai; Tsung-Yin Tang; Kuo-Joan Cheng; Brent L. Selinger; Andrew H.-J. Wang

2004-01-01

256

Oxidation Resistant Graphite Studies  

SciTech Connect

The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

W. Windes; R. Smith

2014-07-01

257

Anticonvulsant drugs, oxidative stress and nitric oxide.  

PubMed

Nitric Oxide (NO) is thought to play a fundamental role in the genesis and the spreading of epileptiform hyperactivity, although its function is unclear and controversial. As a free radical, NO may cause oxidative stress, which is emerging as an important mechanism in the etiology of seizure-induced neuronal death. Here we investigated the role of NO in seizure mechanisms through oxidative stress generation by studying the effect of anticonvulsant drugs such as amino oxyacetic acid (AAOA), valproate (VALP), diazepam (DIAZ) and gabapentin (GBPTNA) on oxidative stress in the brain, estimated as free carbonyls by the method of Dalle and Rossi, and by measuring NO by the indirect method based on the Griess reaction. Results show that, except for AAOA and VALP, anticonvulsants did not significantly affect or decreased free carbonyls, but reversed the oxidative stress produced by pentylenetetrazole (PTZ) induced convulsions. Anticonvulsants except AAOA diminished NO levels and with the exception of VALP, counteracted the increase in NO generated by PTZ. Anticonvulsants decreased oxidative stress and NO especially in hippocampus (HI) and cortex (CX), and reversed PTZ effects on both parameters. PTZ diminished NO in HI, which could be explained since PTZ caused an increase on endothelial NO synthase but a decrease in neuronal NOS expression in this brain area. Since the drugs studied are modulating GABA levels, our results suggest that seizures generated by alterations in GABAergic transmission produce oxidative stress caused by NO, which can be reversed by anticonvulsants. The effects described differ among the brain regions studied and the NO synthase isoform affected. PMID:22423579

Vega Rasgado, L A; Ceballos Reyes, G M; Vega-Diaz, M F

2011-01-01

258

Barium oxide, calcium oxide, magnesia, and alkali oxide free glass  

DOEpatents

A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

2013-09-24

259

METAL OXIDE NANOPARTICLES  

SciTech Connect

This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

2007-10-01

260

High dielectric constant oxides  

Microsoft Academic Search

The scaling of complementary metal oxide semiconductor (CMOS) transistors has led to the silicon dioxide layer used as a gate dielectric becoming so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO{2} with a physically thicker layer of oxides of higher dielectric constant (kappa) or `high K' gate oxides such as hafnium

J. Robertson

2004-01-01

261

Oxidation-Reduction Equilibria  

NSDL National Science Digital Library

This 11-page PDF document is part of an environmental geochemistry course taught by Dr. David Sherman at the University of Bristol. Topics include oxidation-reduction reactions and oxidation states, the Nerst Equation, Eh-pH diagrams, and redox environments in nature. Also included are the calculation of Eh from concentrations and the prediction of stable oxidation states. Helpful diagrams accompany the text.

David M. Sherman

262

The Atomic Structure of Oxide\\/Oxide Interface  

Microsoft Academic Search

The physical and chemical properties of thin or ultrathin oxide film deposited on another oxide bulk or thin film usually differ strongly from the bulk. The properties of the heterostructures ultimately rely on the structure and the chemistry of the oxide\\/oxide interface. Data in the literature indicated that atomically abrupt interfaces between oxides show abnormal electronic and magnetic properties. This

Qi-Hui Wu

2011-01-01

263

Mixed oxide solid solutions  

DOEpatents

The present invention is a mixed oxide solid solution containing a tetravalent and a pentavalent cation that can be used as a support for a metal combustion catalyst. The invention is furthermore a combustion catalyst containing the mixed oxide solid solution and a method of making the mixed oxide solid solution. The tetravalent cation is zirconium(+4), hafnium(+4) or thorium(+4). In one embodiment, the pentavalent cation is tantalum(+5), niobium(+5) or bismuth(+5). Mixed oxide solid solutions of the present invention exhibit enhanced thermal stability, maintaining relatively high surface areas at high temperatures in the presence of water vapor.

Magno, Scott (Dublin, CA); Wang, Ruiping (Fremont, CA); Derouane, Eric (Liverpool, GB)

2003-01-01

264

Catalytic process for formaldehyde oxidation  

NASA Technical Reports Server (NTRS)

Disclosed is a process for oxidizing formaldehyde to carbon dioxide and water without the addition of energy. A mixture of formaldehyde and an oxidizing agent (e.g., ambient air containing formaldehyde) is exposed to a catalyst which includes a noble metal dispersed on a metal oxide which possesses more than one oxidation state. Especially good results are obtained when the noble metal is platinum, and the metal oxide which possesses more than one oxidation state is tin oxide. A promoter (i.e., a small amount of an oxide of a transition series metal) may be used in association with the tin oxide to provide very beneficial results.

Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); D'Ambrosia, Christine M. (Inventor)

1996-01-01

265

Oxidants and oxidation in the Earth's atmosphere  

NASA Technical Reports Server (NTRS)

The 1994 BOC Priestley Conference was held at Bucknell University in Lewisburg, Pennsylvania, from June 24 through June 27, 1994. This conference, managed by the American Chemical Society (ACS), was a joint celebration with the Royal Society of Chemistry (RSC) commemorating Joseph Priestley's arrival in the U.S. and his discovery of oxygen. The basic theme of the conference was 'Oxidants and Oxidation in the Earth's Atmosphere,' with a keynote lecture on the history of ozone. A distinguished group of U.S. and international atmospheric chemists addressed the issues dominating current research and policy agendas. Topics crucial to the atmospheric chemistry of global change and local and regional air pollution were discussed. The program for the conference included four technical sessions on the following topics: (1) Oxidative Fate of Atmospheric Pollutants; (2) Photochemical Smog and Ozone; (3) Stratospheric Ozone; and (4) Global Tropospheric Ozone.

1995-01-01

266

UV Induced Oxidation of Nitric Oxide  

NASA Technical Reports Server (NTRS)

Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated at least in part using in situ UV radiation sources. The sources of the oxidizing species include oxygen and/or hydrogen peroxide. The oxygen may be a component of the gaseous stream or added to the gaseous stream, preferably near a UV radiation source, and is converted to ozone by the UV irradiation. The hydrogen peroxide is decomposed through a combination of vaporization and UV irradiation. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50% by volume and increased in concentration in a continuous process preceding vaporization within the flow channel of the gaseous stream and in the presence of the UV radiation sources.

Parrish, Clyde, F. (Inventor); Luecke, Dale E. (Inventor)

2007-01-01

267

Management of produced water in oil and gas operations  

E-print Network

. The sample is acidified to purge the TIC. Sodium persulfate, a strong oxidizer is added next. The oxidant quickly reacts with organic carbon in the sample at 100oC to form carbon dioxide. When the oxidation reaction is completed, the carbon dioxide... contain less than 200 ppb of TOC. We used distilled or deionized water. Sodium persulfate (100 g/L): It is prepared by dissolving 100 g sodium persulfate into reagent water (1 liter total volume). The solution is stirred and then heated in a bottle...

Patel, Chirag V.

2005-02-17

268

Chemolithotrophic nitrite oxidation by Nitrobacter: coupling with carbon dioxide fixation for growth and influence of metal ions and inorganic compounds of sulfur  

SciTech Connect

The growth of Nitrobacter winogradskyi was completely inhibited by 0.1 mM persulfate, 0.5 mM tetrathionate, or by 5 mM each of dithionite, metabisulfite, or trithionate. The oxygen uptake activity of washed N. agilis cell suspensions was not influenced by persulfate or tetrathionate. Carbon dioxide fixation was insensitive to tetrathionate and in fact an enhancement by tetrathionate was observed. Persulfate inhibited the fixation of carbon dioxide only at a high concentration. The oxygen uptake activity of washed ell suspensions of N. agilis was tested in the presence of copper, nickel, aluminum, uranyl, and molybdate ions. Copper ion was slightly stimulatory at 0.17 M and strongly inhibitory at 17 mM. Molybdate ion showed either slight enhancement or no inhibition at all test concentrations. With the other test ions inhibition of oxygen uptake was observed.

Tsai, Y.L.

1986-01-01

269

Oxidation characteristics of molybdenum-zirconium oxide cermets  

NASA Technical Reports Server (NTRS)

The oxidation of molybdenum is affected by the factors of temperature, the oxygen pressure in the oxidizing atmosphere, and the time of exposure. Studies of the oxidation characteristics of Mo show that the oxidation rate increases strongly when the temperature exceeds 600 C. Investigations of the behavior of cermets with various percentages of zirconium oxide are discussed, taking into account oxidation conditions at temperatures under and above the melting point of molybdenum trioxide.

Heitzinger, B.

1984-01-01

270

OXIDATION OF CHLORINATED ETHANES  

EPA Science Inventory

The oxidation products of seven chlorinated ethanes were identified using Fourier Transform Spectroscopy and long path infrared techniques. Photo-oxidation of each chlorinated ethane was initiated by chlorine atoms in one atmosphere of dry air. The chlorinated reaction products i...

271

Solid Oxide Fuel Cells  

NSDL National Science Digital Library

This article from Gemma Crawley on solid oxide fuel cells appeared in Fuel Cell Today in January 2007. Crawley provides a technological overview of solid oxide fuel cells, information on the development of the technology and the current market for this type of fuel cell. This document may be downloaded in PDF file format.

Crawley, Gemma

272

Stabilized chromium oxide film  

DOEpatents

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Garwin, Edward L. (Los Altos, CA); Nyaiesh, Ali R. (Palo Alto, CA)

1988-01-01

273

Reducible oxide based catalysts  

DOEpatents

A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

2010-04-06

274

Stabilized chromium oxide film  

DOEpatents

Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

Nyaiesh, A.R.; Garwin, E.L.

1986-08-04

275

Lagoons and Oxidation Ponds.  

ERIC Educational Resources Information Center

Presents the 1978 literature review of wastewater treatment. This review covers lagoons and oxidation ponds, and it includes some areas such as improving the effluents from ponds, stabilization ponds, aerated lagoons, and oxidation ditches. A list of 36 references is also presented. (HM)

O'Brien, W. J.

1978-01-01

276

Oxides, Oxides, and More Oxides: High-? Oxides, Ferroelectrics, Ferromagnetics, and Multiferroics  

Microsoft Academic Search

We review and critique the recent developments on multifunctional oxide materials, which are gaining a good deal of interest. Recongnizing that this is a vast area, the focus of this treatment is mainly on high-? dielectric, ferroelectric, magnetic, and multiferroic materials. Also, we consider ferrimagnetic oxides in the context of the new, rapidly developing field of negative-index metamaterials. This review

N. Izyumskaya; Ya. Alivov; H. Morkoç

2009-01-01

277

Variable-Temperature Electrical Measurements of Zinc Oxide/Tin Oxide-Cosubstituted Indium Oxide  

E-print Network

Variable-Temperature Electrical Measurements of Zinc Oxide/Tin Oxide-Cosubstituted Indium Oxide A-), undoped In2O3, and indium-tin oxide (ITO) were studied vs cation composition, state of reduction of choice, tin-doped indium oxide (ITO) has a typical conductivity of 1-5 × 103 S/cm and a transpar- ency

Poeppelmeier, Kenneth R.

278

Nitric Oxide Nanoparticle Technology  

PubMed Central

Staphylococcus aureus infections account for the majority of skin and soft tissue infections in the United States. Staphylococcus aureus is rapidly evolving resistance to contemporary topical as well as systemic antibiotics. Alternatives to current treatment options for skin and soft tissue infections are needed for more effective treatment now and in the future. Nitric oxide's proven roles in both wound repair and as an antimicrobial agent make it an excellent candidate for the treatment of skin infections. Recent attempts at novel nitric oxide therapies, in the form of nitric oxide donors, have shown limited potential in treating cutaneous infection. However, more recent developments in nitric oxide delivery, using nitric oxide nanoparticle technology, demonstrate substantial promise in the promotion of wound repair and eradication of skin and soft tissue infections. PMID:20725551

Englander, Laura

2010-01-01

279

Biocompatibility of Graphene Oxide  

NASA Astrophysics Data System (ADS)

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 ?g/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 ?g/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.

Wang, Kan; Ruan, Jing; Song, Hua; Zhang, Jiali; Wo, Yan; Guo, Shouwu; Cui, Daxiang

2010-12-01

280

Biocompatibility of Graphene Oxide  

NASA Astrophysics Data System (ADS)

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 ?g/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 ?g/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.

Wang, Kan; Ruan, Jing; Song, Hua; Zhang, Jiali; Wo, Yan; Guo, Shouwu; Cui, Daxiang

2011-12-01

281

Hippocampus and nitric oxide.  

PubMed

Since it was first identified to play an important role in relaxation of blood vessels, nitric oxide has been demonstrated to regulate many biological processes, especially in the central nervous system. Of the three types of enzymes that produce nitric oxide in humans and rodents, neuronal type is found almost exclusively in the nervous system. This gaseous molecule is a nonclassical neurotransmitter, which maintains the activities of neural cells and regulates the normal functions of brain. It appears to play a role in promoting the transfer of nerve signals from one neuron to another, maintaining the synaptic strength. Meanwhile, nitric oxide is a unique regulator on neurogenesis and synaptogenesis, producing the positive or negative effects upon different signal pathways or cellular origins and locations. Based on its significant roles in neural plasticity, nitric oxide is involved in a number of central nervous diseases, such as ischemia, depression, anxiety, and Alzheimer's disease. Clarifying the profiles of nitric oxide in the brain tissues and its participation in pathophysiological processes opens a new avenue for development of new therapeutic strategies. Thus, this chapter specifies the effects of nitric oxide in the hippocampus, a key structure implicated in the modulation of mood and memories, exhibiting the trend of future research on nitric oxide. PMID:25189386

Hu, Yao; Zhu, Dong-Ya

2014-01-01

282

NEPTUNIUM OXIDE PROCESSING  

SciTech Connect

The Savannah River Site's HB-Line Facility completed a campaign in which fifty nine cans of neptunium oxide were produced and shipped to the Idaho National Laboratory in the 9975 shipping container. The neptunium campaign was divided into two parts: Part 1 which consisted of oxide made from H-Canyon neptunium solution which did not require any processing prior to conversion into an oxide, and Part 2 which consisted of oxide made from additional H-Canyon neptunium solutions which required processing to purify the solution prior to conversion into an oxide. The neptunium was received as a nitrate solution and converted to oxide through ion-exchange column extraction, precipitation, and calcination. Numerous processing challenges were encountered in order make a final neptunium oxide product that could be shipped in a 9975 shipping container. Among the challenges overcome was the issue of scale: translating lab scale production into full facility production. The balance between processing efficiency and product quality assurance was addressed during this campaign. Lessons learned from these challenges are applicable to other processing projects.

Jordan, J; Watkins, R; Hensel, S

2009-05-27

283

Transpassive oxidation of pyrite  

SciTech Connect

The electrochemical behavior of mineral and coal pyrites in basic borate/sulfate solutions was investigated using cyclic voltammetry with both stationary and rotating disk electrode. Emphasis was centered on transpassive oxidation. In the transpassive region, 0.4 to 0.8 V (SCE), aggressive oxidation of pyrite occurred. The reaction products in this region are Fe(III) oxides, sulfate ion, and partially oxidized sulfur intermediates. The formation of sulfur and polysulfides was identified by in situ Raman spectroscopy. Exposure of pyrite to anodic potentials higher than the transpassive region resulted in rapid oxidation of sulfur intermediates to sulfate ion. The effect of electrode rotation speed, electrode precondition time, and upper potential of the scan in the transpassive region was observed to be critical to the formation of sulfur intermediates. Sulfur intermediates, formed in the transpassive region, dramatically affected subsequent oxidation reactions occurring in the lower potential region. The magnitude of two dominant oxidation peaks, a ferrous hydroxide peak and an iron sulfide peak, observed in this region correlated directly with the quantity of sulfur intermediates formed in the transpassive region. This effect was less pronounced for coal pyrites compared to mineral pyrite.

Zhu, Ximeng; Bodily, D.M.; Wadsworth, M.E. (Univ. of Utah, Salt Lake City (United States). College of Mines and Earth Sciences)

1993-07-01

284

Wet Oxidation Process  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the wet oxidation process. This animation "illustrates the chemistry of a wet thermal oxidation process that is used to grow silicon dioxide (SiO2) on a silicon (Si) wafer. In a wet oxidation process, water vapor (H2O) interacts with the silicon atoms at the SiO2-Si interface to form SiO2. This process is discussed in more detail in the Deposition Overview for MEMS Learning Module" found on the SCME website.

285

Dry Thermal Oxidation Process  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the dry thermal oxidation process. This animation "illustrates the chemistry of a dry thermal oxidation process that is used to grow silicon dioxide (SiO2) on a silicon (Si) wafer. In a dry oxidation process, oxygen gas (O2) interacts with the silicon atoms at the SiO2 - Si interface to form SiO2. This process is discussed in more detail in the Deposition Overview for MEMS Learning Module" which can be found on the SCME website along with supplementary materials. 

286

Treatment of exhaust gas containing sulfur oxides and nitrogen oxides  

Microsoft Academic Search

A method of treating an exhaust gas at a high temperature containing nitrogen oxides and sulfur oxides is described. The method consists of bringing the exhaust gas into contact with an absorbing solution containing at least an iron chelate salt and potassium sulfite to thereby convert said nitrogen oxides and sulfur oxides into a mixture of potassium imidodisulfonate, potassium dithionate

Y. Kudo; K. Nomoto

1981-01-01

287

Oxide nanomaterials Selbach, Inorganic  

E-print Network

Oxide nanomaterials Selbach, Inorganic Materials and Ceramics Research GroupAvity within ceramic engineering, solid state chemistry, nanoparAcles, thin films · Intermediate band solar cells · BaTery materials and tesAng · SOFC and proton

288

Oxidative Tritium Decontamination System  

DOEpatents

The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The OTDS employs ozone gas as oxidizing agent to convert elemental tritium to tritium oxide. Tritium oxide vapor and excess ozone gas is purged from the OTDS, for discharge to atmosphere or transport to further process. An effluent stream is subjected to a catalytic process for the decomposition of excess ozone to diatomic oxygen. One of two configurations of the OTDS is employed: dynamic apparatus equipped with agitation mechanism and large volumetric capacity for decontamination of light items, or static apparatus equipped with pressurization and evacuation capability for decontamination of heavier, delicate, and/or valuable items.

Gentile, Charles A. (Plainsboro, NJ), Guttadora, Gregory L. (Highland Park, NJ), Parker, John J. (Medford, NJ)

2006-02-07

289

Mercuric oxide poisoning  

MedlinePLUS

Mercuric oxide may be found in some: Button batteries (batteries containing mercury are no longer sold in the ... stomach ( gastric lavage ) Any person who swallowed a battery will need immediate x-rays to make sure ...

290

Controlled CO preferential oxidation  

DOEpatents

Method is described for controlling the supply of air to a PROX (PReferential OXidation for CO cleanup) reactor for the preferential oxidation in the presence of hydrogen wherein the concentration of the hydrogen entering and exiting the PROX reactor is monitored, the difference there between correlated to the amount of air needed to minimize such difference, and based thereon the air supply to the PROX reactor adjusted to provide such amount and minimize such difference. 2 figs.

Meltser, M.A.; Hoch, M.M.

1997-06-10

291

CCMR: Cobalt Oxide Nanocubes  

NSDL National Science Digital Library

This research studies and conduct tests on cobalt oxide nanocubes, a nanoparticle that will be used in several applications. Silica nanoparticles are round shape while cobalt oxide nanocubes are cubic shaped making them a better option. Shear Thickening Fluid testing has indicated that the technology allows conventional ballistic fabrics to amplify the level and quality of protection they provide without compromising weight, comfort or flexibility.

Lee, Sabrina R.

2009-08-15

292

Oxidative Degradation of Monoethanolamine  

Microsoft Academic Search

Oxidative degradation of monoethanolamine (MEA) was studied under typical absorber condition of 55 °C. The rate of evolution of NH 3, which was indicative of the overall rate of degradation, was measured continuously in a batch system sparged with air. Dissolved iron from 0.0001 mM to 1 mM yields oxidation rates from 0.37 to 2 mM\\/hr in MEA solutions loaded

Susan Chi; Gary T. Rochelle

2002-01-01

293

Nitrogen Oxides (GCMP)  

NSDL National Science Digital Library

Nitrogen Oxides: this is a resource in the collection "General Chemistry Multimedia Problems". Two of the most important nitrogen oxides, N2O4 and NO2, are in equilibrium with each other. We are interested in how this equilibrium shifts with temperature. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

294

Alkane oxidation catalysts  

SciTech Connect

This invention involves HPA and POA catalyzed, selective oxidation of alkanes with oxygen in the liquid phase at relatively mild conditions (usually under 200/sup 0/C) to a product rich in alcohol and with little or no burn of alkane to carbon oxides. The HPAs and POAs are promoted with certain metals and/or with an azide and may possess certain other modifications from a conventional HPA or POA.

Lyons, J.E.; Ellis, P.E. Jr.; Myers, H.K. Jr.; Suld, G.; Langdale, W.A

1989-02-07

295

Silver(II) Oxide or Silver(I,III) Oxide?  

ERIC Educational Resources Information Center

The often called silver peroxide and silver(II) oxide, AgO or Ag[subscript 2]O[subscript 2], is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide.…

Tudela, David

2008-01-01

296

Oxidation During NOMADSS  

NASA Astrophysics Data System (ADS)

The NSF NOMADSS (Nitrogen, Oxidants, Mercury and Aerosol Distributions, Sources and Sinks) study covered a broad spectrum of topics ranging from biogenic emissions, mercury oxidation, to the characterization of HONO sources and sinks. The study provided a rich data set with measurements in environments ranging from the clean free troposphere, to boundary layer measurements with high BVOC or anthropogenic influences. Here measurements from the University of Colorado Sulfuric, OH, and MSA Instrument, SUOMI, will be presented and OH oxidation processes in these various regions will be explored. Sulfuric acid production rates in power plant plumes, and the role of OH in mercury oxidation will be discussed as well as the use of OH in constraining HONO steady state calculations. A recently discovered attribute of the SUOMI is its sensitivity to stabilized Criegee intermediates, sCIs. These measurements reveal enhanced concentrations of sCI over regions with high BVOC emissions. This observation leads to an increase in the overall oxidizing capacity of these regions over that of OH oxidation alone. If time or size constraints allow, measurements indicating a continental source of MSA production will also be presented.

Mauldin, L.; Schardt, N.; Cantrell, C. A.; Ambrose, J. L.; Gratz, L.; Jaffe, D. A.; Ye, C.; Zhou, X.; Hornbrook, R. S.; Hills, A. J.; Apel, E. C.

2013-12-01

297

Oxidative Stress in Schizophrenia  

PubMed Central

Increasing evidence indicates that oxidative damage exists in schizophrenia. Available literature about possible mechanisms of oxidative stress induction was reviewed. Furthermore, possibilities of measuring biomarkers of schizophrenia outside the central nervous system compartment, their specificity for different types of schizophrenia and potential therapeutic strategies to prevent oxidative injuries in schizophrenia were discussed. Data were extracted from published literature found in Medline, Embase, Biosis, Cochrane and Web of Science, together with hand search of references. Search terms were: schizophrenia, oxidative stress, antipsychotics, antioxidants and fatty acids. Finding a sensitive, specific and non invasive biomarker of schizophrenia, which could be measured in peripheral tissue, still stays an important task. Antioxidant enzymes, markers of lipid peroxidation, oxidatively modified proteins and DNA are most commonly used. As it considers the supplemental therapy, according to our meta-analysis vitamin E could potentially improve tardive dyskinesia, while for the effect of therapy with polyunsaturated fatty acids there is no clear evidence. Oxidative stress is a part of the pathology in schizophrenia and appears as a promising field to develop new therapeutic strategies. There is a need for well designed, placebo controlled trials with supplementation therapy in schizophrenia. PMID:22131939

Boškovi?, Marija; Vovk, Tomaž; Kores Plesni?ar, Blanka; Grabnar, Iztok

2011-01-01

298

Selective heterogeneous alkane oxidation  

SciTech Connect

Oxydehydrogenation of alkanes could provide significant advantages over steam cracking or catalytic dehydrogenation processes. High-temperature oxidations allow only limited selectivities due to homogeneous gas phase oxidation reactions which compete with surface reactions to produce significant amounts of carbon monoxide and carbon dioxide. Union Carbide`s molybdenum-vanadium-niobium oxide (MoVNb) and vanadyl pyrophosphate catalysts were compared with other literature oxidation catalysts for the oxidation of alkanes to the corresponding olefins at temperatures below 450{degrees}C. In addition, MoVNb catalysts of different compositions with and without promoters were explored for their abilities to selectively oxydehydrogenate alkanes. Alkene selectivity and alkane conversion in ethane and propane oxidation were correlated with the presence and amounts of different catalyst species determined for varying compositions of MoVNb catalysts using XPS, Raman, and XRD. Roles of the various catalyst species are proposed as a result of these studies. V is the active component and more V{sup 5+} favors oxydehydrogenation. Nb disperses V and prevents crystallization. Mo and possibly other promoters adjust the V{sup 5+}/V{sup 4+} ratio.

Warren, B.K.; Salaita, G.N. [Union Carbide Corporation, South Charleston, WV (United States)

1996-10-01

299

Staphylococcal response to oxidative stress  

PubMed Central

Staphylococci are a versatile genus of bacteria that are capable of causing acute and chronic infections in diverse host species. The success of staphylococci as pathogens is due in part to their ability to mitigate endogenous and exogenous oxidative and nitrosative stress. Endogenous oxidative stress is a consequence of life in an aerobic environment; whereas, exogenous oxidative and nitrosative stress are often due to the bacteria's interaction with host immune systems. To overcome the deleterious effects of oxidative and nitrosative stress, staphylococci have evolved protection, detoxification, and repair mechanisms that are controlled by a network of regulators. In this review, we summarize the cellular targets of oxidative stress, the mechanisms by which staphylococci sense oxidative stress and damage, oxidative stress protection and repair mechanisms, and regulation of the oxidative stress response. When possible, special attention is given to how the oxidative stress defense mechanisms help staphylococci control oxidative stress in the host. PMID:22919625

Gaupp, Rosmarie; Ledala, Nagender; Somerville, Greg A.

2012-01-01

300

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Wellinghoff, Stephen T. (Inventor)

1994-01-01

301

Metal oxide-polymer composites  

NASA Technical Reports Server (NTRS)

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Wellinghoff, Stephen T. (Inventor)

1997-01-01

302

OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE  

E-print Network

OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J MANGANESE OXIDE by Brandon J. Lafferty Approved..........................................................................................................1 Manganese Oxides...................................

Sparks, Donald L.

303

Environmental and Microbiological Characteristics of Managed Urban Turfgrass Systems  

E-print Network

(DON) using a persulfate oxidation method; and for dissolved organic phosphorus (DOP) with an ascorbic acid method. Microbial populations were characterized with respect to bacterial and fungal numbers by standard plate counts; carbon substrate...

Caster, Stephen

2010-01-16

304

Adsorption of Sodium Hexanoate on ?-Alumina  

E-print Network

carbons and sodium persulfate as oxidizer supplied by GE Analytical instruments Ltd. The adsorption isotherm of sodium hexanoate was determined by the solution depletion method, where the change in adsorbate concentration (depletion) after contact...

Lee, Seung Yeon; Welbourn, Rebecca; Clarke, Stuart; Skoda, Maximilian W. A.; Clifton, Luke; Zarbakhsh, Ali

2013-06-27

305

Stabilized tin-oxide-based oxidation/reduction catalysts  

NASA Technical Reports Server (NTRS)

The invention described herein involves a novel approach to the production of oxidation/reduction catalytic systems. The present invention serves to stabilize the tin oxide reducible metal-oxide coating by co-incorporating at least another metal-oxide species, such as zirconium. In one embodiment, a third metal-oxide species is incorporated, selected from the group consisting of cerium, lanthanum, hafnium, and ruthenium. The incorporation of the additional metal oxide components serves to stabilize the active tin-oxide layer in the catalytic process during high-temperature operation in a reducing environment (e.g., automobile exhaust). Moreover, the additional metal oxides are active components due to their oxygen-retention capabilities. Together, these features provide a mechanism to extend the range of operation of the tin-oxide-based catalyst system for automotive applications, while maintaining the existing advantages.

Jordan, Jeffrey D. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Leighty, Bradley D. (Inventor); Watkins, Anthony Neal (Inventor); Schryer, Jacqueline L. (Inventor); Oglesby, Donald M. (Inventor); Gulati, Suresh T. (Inventor); Summers, Jerry C. (Inventor)

2008-01-01

306

Switching Oxide Traps  

NASA Technical Reports Server (NTRS)

We consider radiation-induced charge trapping in SiO2 dielectric layers, primarily from the point of view of CMOS devices. However, SiO2 insulators are used in many other ways, and the same defects occur in other contexts. The key studies, which determined the nature of the oxide charge traps, were done primarily on gate oxides in CMOS devices, because that was the main radiation problem in CMOS at one time. There are two major reviews of radiation-induced oxide charge trapping already in the literature, which discuss the subject in far greater detail than is possible here. The first of these was by McLean et al. in 1989, and the second, ten years later, was intended as an update, because of additional, new work that had been reported. Basically, the picture that has emerged is that ionizing radiation creates electron-hole pairs in the oxide, and the electrons have much higher mobility than the holes. Therefore, the electrons are swept out of the oxide very rapidly by any field that is present, leaving behind any holes that escape the initial recombination process. These holes then undergo a polaron hopping transport toward the Si/SiO2 interface (under positive bias). Near the interface, some fraction of them fall into deep, relatively stable, long-lived hole traps. The nature and annealing behavior of these hole traps is the main focus of this paper.

Oldham, Timothy R.

2003-01-01

307

Effect of Surface Oxide Transformation on CO Oxidation  

NASA Astrophysics Data System (ADS)

Under sub-atmospheric conditions, many metal catalyst surfaces for CO oxidation transform to the oxide phase with higher catalytic activity than chemisorbed oxygen. The surface phase transformation from metal to its oxide could be by collective oxidation of the adsorbed oxygen sites as soon as their coverage reaches a global critical threshold, or such oxidation may be restricted to small patches of the surface, which is driven by the local coverage. In this communication, we investigate the effect of the latter on the phase diagram and the CO2 production rate behavior using a kinetic Monte Carlo surface reaction lattice gas model for CO oxidation.

Sinha, I.; Mukherjee, A. K.

2015-02-01

308

A time-based flow injection–cold vapor–atomic absorption spectrometry system with on-line microwave sample pre-treatment for the determination of inorganic and total mercury in urine 1 Presented at the Flow Analysis VII Conference held in Piracicaba, Brazil from 23–26 August 1997. 1  

Microsoft Academic Search

A time based injection system used in conjunction with cold vapor generation atomic absorption spectrometry and microwave-aided heating oxidation with potassium persulfate has been developed for the determination of total and inorganic mercury in urine samples. Inorganic mercury is determined after reduction with SnCl2 while total mercury is determined after an on-line oxidation step with persulfate prior to the reduction

M Gallignani; H Bahsas; M. R Brunetto; M Burguera; J. L Burguera; Y Petit de Peña

1998-01-01

309

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

1999-01-01

310

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-17

311

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell.

Ahmed, Shabbir (Bolingbrook, IL); Kumar, Romesh (Naperville, IL); Krumpelt, Michael (Naperville, IL)

2001-01-01

312

Methanol partial oxidation reformer  

DOEpatents

A partial oxidation reformer is described comprising a longitudinally extending chamber having a methanol, water and an air inlet and an outlet. An igniter mechanism is near the inlets for igniting a mixture of methanol and air, while a partial oxidation catalyst in the chamber is spaced from the inlets and converts methanol and oxygen to carbon dioxide and hydrogen. Controlling the oxygen to methanol mole ratio provides continuous slightly exothermic partial oxidation reactions of methanol and air producing hydrogen gas. The liquid is preferably injected in droplets having diameters less than 100 micrometers. The reformer is useful in a propulsion system for a vehicle which supplies a hydrogen-containing gas to the negative electrode of a fuel cell. 7 figs.

Ahmed, S.; Kumar, R.; Krumpelt, M.

1999-08-24

313

Oxidative Tritium Decontamination System  

SciTech Connect

The Princeton Plasma Physics Laboratory, Tritium Systems Group has developed and fabricated an Oxidative Tritium Decontamination System (OTDS), which is designed to reduce tritium surface contamination on various components and items. The system is configured to introduce gaseous ozone into a reaction chamber containing tritiated items that require a reduction in tritium surface contamination. Tritium surface contamination (on components and items in the reaction chamber) is removed by chemically reacting elemental tritium to tritium oxide via oxidation, while purging the reaction chamber effluent to a gas holding tank or negative pressure HVAC system. Implementing specific concentrations of ozone along with catalytic parameters, the system is able to significantly reduce surface tritium contamination on an assortment of expendable and non-expendable items. This paper will present the results of various experimentation involving employment of this system.

Charles A. Gentile; John J. Parker; Gregory L. Guttadora; Lloyd P. Ciebiera

2002-02-11

314

Microbial Formaldehyde Oxidation  

SciTech Connect

This project analyzed how cells sense and generate energy from formaldehyde oxidation. Formaldehyde is a toxin that is produced naturally, chemically or by metabolism of a wide variety of methyl-containing compounds. Our goals are to identify how cells sense the presence of this toxic compound and determine how they generate energy and nutrients from the oxidation of formaldehyde. This research capitalizes on the role of the Rhodobacter sphaeroides glutathione dependent formaldehyde dehydrogenase (GSH FDH) in a formaldehyde oxidation pathway that is apparently found in a wide variety of microbes, plants and animals. Thus, our findings illustrate what is required for a large variety of cells to metabolize this toxic compound. A second major focus of our research is to determine how cells sense the presence of this toxic compound and control the expression of gene products required for its detoxification.

Timothy J. Donohue

2004-12-09

315

Nitroalkane Oxidation by Streptomycetes  

PubMed Central

Crude cell-free extracts of nine strains of Streptomyces tested for nitroalkane-oxidizing activity showed production of nitrous acid from 2-nitropropane, 1-nitropropane, nitroethane, nitromethane, and 3-nitropropionic acid. These substrates were utilized in most strains but to a decreasing extent in the order given, and different strains varied in their relative efficiency of oxidation. p-Nitrobenzoic acid, p-aminobenzoic acid, enteromycin, and ?-nitro-l-arginine were not attacked. d-Amino acid oxidase, glucose oxidase, glutathione S-transferase, and xanthine oxidase, enzymes potentially responsible for the observed oxidations in crude cellfree extracts, were present at concentrations too low to play any significant role. A nitroalkane-oxidizing enzyme from streptozotocin-producing Streptomyces achromogenes subsp. streptozoticus was partially purified and characterized. It catalyzes the oxidative denitrification of 2-nitropropane as follows: 2CH3CH(NO2)CH3 + O2 ? 2CH3COCH3 + 2HNO2. At the optimum pH of 7.5 of the enzyme, 2-nitropropane was as good a substrate as its sodium salt; t-nitrobutane was not a substrate. Whereas Tiron, oxine, and nitroxyl radical acted as potent inhibitors of this enzyme, superoxide dismutase was essentially without effect. Sodium peroxide abolished a lag phase in the progress curve of the enzyme and afforded stimulation, whereas sodium superoxide did not affect the reaction. Reducing agents, such as glutathione, reduced nicotinamide adenine dinucleotide, and nicotinamide adenine dinucleotide phosphate, reduced form, as well as thiol compounds, were strongly inhibitory, but cyanide had no effect. The S. achromogenes enzyme at the present stage of purification is similar in many respects to the enzyme 2-nitropropane dioxygenase from Hansenula mrakii. The possible involvement of the nitroalkane-oxidizing enzyme in the biosynthesis of antibiotics that contain a nitrogen-nitrogen bond is discussed. PMID:33965

Dhawale, Motiram R.; Hornemann, Ulfert

1979-01-01

316

Magnetism of cuprate oxides  

SciTech Connect

A review is given of current neutron scattering experiments on cuprate oxides. We first discuss the extensive neutron measurements on high-Tc oxides: La{sub 2-x}Sr{sub x}CuO{sub 4} and related (La{sub 1.6-x}Nd{sub 0.4})Sr{sub x}CuO{sub 4}. The second topic is the spin- Peierls system Cu{sub 1-x}Zn{sub x}GeO{sub 3}, where a new type of antiferromagnetic phase has been discovered. 17 refs, 8 figs.

Shirane, G.

1996-11-01

317

Tetraalykylammonium polyoxoanionic oxidation catalysts  

DOEpatents

Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H.sub.e-z ›(n-C.sub.4 H.sub.9).sub.4 N!.sub.z (XM.sub.11 M'O.sub.39).sup.-e The M' (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

Ellis, Paul E. (Downingtown, PA); Lyons, James E. (Wallingford, PA); Myers, Jr., Harry K. (Cochranville, PA); Shaikh, Shahid N. (Media, PA)

1998-01-01

318

Tetraalklylammonium polyoxoanionic oxidation catalysts  

DOEpatents

Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H{sub e{minus}z}[(n-C{sub 4}H{sub 9}){sub 4}N]{sub z}(XM{sub 11}M{prime}O{sub 39}){sup {minus}e}. The M{prime} (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

Ellis, P.E.; Lyons, J.E.; Myers, H.K. Jr.; Shaikh, S.N.

1998-10-06

319

Molecular water oxidation catalyst  

DOEpatents

A dimeric composition of the formula: ##STR1## wherein L', L", L'", and L"" are each a bidentate ligand having at least one functional substituent, the ligand selected from bipyridine, phenanthroline, 2-phenylpyridine, bipyrimidine, and bipyrazyl and the functional substituent selected from carboxylic acid, ester, amide, halogenide, anhydride, acyl ketone, alkyl ketone, acid chloride, sulfonic acid, phosphonic acid, and nitro and nitroso groups. An electrochemical oxidation process for the production of the above functionally substituted bidentate ligand diaqua oxo-bridged ruthenium dimers and their use as water oxidation catalysts is described.

Gratzel, Michael (St. Sulpice, CH); Munavalli, Shekhar (Bel Air, MD); Pern, Fu-Jann (Lakewood, CO); Frank, Arthur J. (Lakewood, CO)

1993-01-01

320

Thermally stable mixed oxide gels  

SciTech Connect

A process is disclosed for cogelling a smectite with an inorganic metal oxide which is unstable with respect to retaining a high surface area, to produce a cogel of high surface area which has good retention of surface area at high temperatures. Suitable smectites for the practice of this invention are hectorite, chlorite, montmorillionite, beidellite, or admixtures of two or more of these materials with each other or with other materials, or the like. Exemplary of inorganic oxide gels suitable for the practice of this invention are the Group IV-B metal oxides, especially titanium oxide, and other metal oxides such as the oxides of thorium, uranium, silicon, aluminum, and the like.

Wheelock, K.S.

1985-02-12

321

Low temperature oxidation of plutonium  

SciTech Connect

The initial oxidation of gallium stabilized {delta}-plutonium metal at 193 K has been followed using x-ray photoelectron spectroscopy. On exposure to Langmuir quantities of oxygen, plutonium rapidly forms a trivalent oxide followed by a tetravalent plutonium oxide. The growth modes of both oxides have been determined. Warming the sample in vacuum, the tetravalent oxide reduces to the trivalent oxide. The kinetics of this reduction reaction have followed and the activation energy has been determined to be 38.8 kJ mol{sup -1}.

Nelson, Art J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Roussel, Paul [AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

2013-05-15

322

Ultra-thin titanium oxide  

NASA Astrophysics Data System (ADS)

We demonstrate the fabrication of ultra-thin titanium oxide films by plasma-induced surface oxidation. Ellipsometry measurements indicate an oxide thickness of about 2 nm. Electrical characterization was performed on microscale and nanoscale metal-insulator-metal tunneling diodes. Electrical fields up to 22 MV/cm were applied without destroying the titanium oxide films. The current-voltage-characteristic of the diodes are found to be asymmetric with respect to zero bias when employing electrodes with different work functions. The permittivity of the ultra-thin titanium oxide was determined to be less than 6, which is the smallest permittivity that has been reported for titanium oxide.

Bareiß, M.; Kälblein, D.; Jirauschek, C.; Exner, A.; Pavlichenko, I.; Lotsch, B.; Zschieschang, U.; Klauk, H.; Scarpa, G.; Fabel, B.; Porod, W.; Lugli, P.

2012-08-01

323

Oxidative stress in Alzheimer's disease.  

PubMed

Oxidative stress plays a significant role in the pathogenesis of Alzheimer's disease (AD), a devastating disease of the elderly. The brain is more vulnerable than other organs to oxidative stress, and most of the components of neurons (lipids, proteins, and nucleic acids) can be oxidized in AD due to mitochondrial dysfunction, increased metal levels, inflammation, and ?-amyloid (A?) peptides. Oxidative stress participates in the development of AD by promoting A? deposition, tau hyperphosphorylation, and the subsequent loss of synapses and neurons. The relationship between oxidative stress and AD suggests that oxidative stress is an essential part of the pathological process, and antioxidants may be useful for AD treatment. PMID:24664866

Chen, Zhichun; Zhong, Chunjiu

2014-04-01

324

Novel oxide amorphous semiconductors: transparent conducting amorphous oxides  

Microsoft Academic Search

A working hypothesis to find wide gap oxide semiconductors was proposed on the basis of simple considerations. The hypothesis predicts that amorphous double oxides composed of heavy metal cations (HMCs) with an electronic configuration (n ? 1)d10s0 are promising candidates for a novel class of amorphous semiconductors. Electrical and optical properties of three amorphous double oxides composed of the HMCs,

Hideo Hosono; Masahiro Yasukawa; Hiroshi Kawazoe

1996-01-01

325

Iridium oxide and palladium modified nitric oxide microsensor  

Microsoft Academic Search

An electrochemical microsensor, constructed by chemical modification of Nafion, poly(vinyl pyridine) (PVP), palladium and iridium oxide onto a platinum microelectrode, has been developed for the determination of nitric oxide (NO). This microsensor exhibits excellent catalytic activity toward NO oxidation, which is confirmed by differential pulse voltammetry. Cyclic voltammetry and differential pulse amperometry are also performed to measure NO. The catalytic

Yuezhong Xian; Wenliang Sun; Jian Xue; Min Luo; Litong Jin

1999-01-01

326

Synthetic water-oxidation catalysts for artificial photosynthetic water oxidation  

Microsoft Academic Search

This review focuses primarily on homogeneous catalysts for the oxidation of water, but does include selected heterogeneous systems. It does not attempt to summarize all chemistry related to systems that are capable of oxidizing water. In particular, heterogeneous catalysts that have no direct relevance to understanding the WOC [water-oxidizing complex] are not discussed in detail. Neither are nonbiomimetic systems for

W. Ruettinger; G. Charles Dismukes

1997-01-01

327

Nanostructured transition metal oxides useful for water oxidation catalysis  

DOEpatents

The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

Frei, Heinz M; Jiao, Feng

2013-12-24

328

Oxidative Reforming of Biodiesel Over Molybdenum (IV) Oxide  

E-print Network

Oxidative Reforming of Biodiesel Over Molybdenum (IV) Oxide Jessica Whalen, Oscar Marin Flores, Su molybdenum dioxide displays excellent behavior as catalytic material for the oxidative reforming of both yield. High conversion and yield percentages with isooctane and dodecane make molybdenum a good

Collins, Gary S.

329

Diesel engine exhaust oxidizer  

SciTech Connect

This patent describes a diesel engine exhaust oxidizing device. It comprises: an enclosure having an inlet for receiving diesel engine exhaust, a main flow path through the enclosure to an outlet of the enclosure, a by-ass through the enclosure, and a microprocessor control means.

Kammel, R.A.

1992-06-16

330

Solid Oxide Fuel Cells  

NSDL National Science Digital Library

This reference sheet provides some basic information on solid oxide fuel cells. This document includes information on the basic operation of these fuel cells and some useful graphics. This document would probably be more useful for students who already have a basic understanding of fuel cells.This document may be downloaded in PDF file format.

331

Zinc oxide whiskers  

Microsoft Academic Search

This paper describes the first experiments on the production of zinc oxide whiskers in air without crystallization chambers\\u000a or reactors, using CO2-laser radiation. The features of their exciton luminescence are studied, and they are compared with bulk single crystals\\u000a and epitaxial layers of Zno.

B. M. Ataev; I. K. Kamilov; V. V. Mamedov

1997-01-01

332

Technology Offer Oxidized Phospholipids -  

E-print Network

Technology Offer Oxidized Phospholipids - The new Promise in Skin Cancer Keywords Skin cancer Lipid apoptosis in cultured skin cancer cells but affect "healthy" melanocytes and keratinocytes to a much lesser for the treatment of various types of skin cancer and skin cancer precursors as well as other malignant tumors. 3

333

Monoliths in catalytic oxidation  

Microsoft Academic Search

Catalytic combustion is useful to avoid emission of nitrogen oxides, to combust fuel gas of different calorific levels, and to combust low contents of badly smelling or hazardous gaseous compounds. After dealing with some characteristics of catalytic combustion it is argued that catalytic combustion to a final temperature lower than about 800°C calls for a rapid transport of thermal energy

John W. Geus; Joep C. van Giezen

1999-01-01

334

Highly oxidized superconductors  

DOEpatents

Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known synthesis in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed. 16 figs.

Morris, D.E.

1994-09-20

335

Grazing and Nitrous Oxide  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nitrous oxide emission rates are typically measured using ‘bottom up’ methods which involve placing airtight chambers over the soil surface and measuring the change in gas concentration over short time periods (e.g., 15-60 min.). Emission rates vary substantially both spatially and temporally and ma...

336

Highly oxidized superconductors  

DOEpatents

Novel superconducting materials in the form of compounds, structures or phases are formed by performing otherwise known syntheses in a highly oxidizing atmosphere rather than that created by molecular oxygen at atmospheric pressure or below. This leads to the successful synthesis of novel superconducting compounds which are thermodynamically stable at the conditions under which they are formed.

Morris, Donald E. (Kensington, CA)

1994-01-01

337

CONTROLLING NITROGEN OXIDES  

EPA Science Inventory

Recent research indicates that nitrogen oxides (NOx) could be one of the most troublesome air pollutants of the 1980's. More than 20 million metric tons of NOx are annually polluting our air as a result of the widespread combustion of fossil fuels in power plants, industrial boil...

338

Sulfite-oxidizing enzymes.  

PubMed

Sulfite-oxidizing enzymes (SOEs) are molybdenum enzymes that exist in almost all forms of life where they carry out important functions in protecting cells and organisms against sulfite-induced damage. Due to their nearly ubiquitous presence in living cells, these enzymes can be assumed to be evolutionarily ancient, and this is reflected in the fact that the basic domain architecture and fold structure of all sulfite-oxidizing enzymes studied so far are similar. The Mo centers of all SOEs have five-coordinate square pyramidal coordination geometry, which incorporates a pyranopterin dithiolene cofactor. However, significant differences exist in the quaternary structure of the enzymes, as well as in the kinetic properties and the nature of the electron acceptors used. In addition, some SOEs also contain an integral heme group that participates in the overall catalytic cycle. Catalytic turnover involves the paramagnetic Mo(V) oxidation state, and EPR spectroscopy, especially high-resolution pulsed EPR spectroscopy, provides detailed information about the molecular and electronic structure of the Mo center and the Mo-based sulfite oxidation reaction. PMID:25261289

Kappler, Ulrike; Enemark, John H

2015-03-01

339

Active oxide nanophotonics  

NASA Astrophysics Data System (ADS)

Materials that can be manipulated electrically or mechanically to induce a change in their intrinsic properties are highly relevant when suitably integrated with current technologies. These "active" materials, such as oxide-based ferroelectrics or materials with easily accessible changes of phase, find extensive use as mechanical resonators, solid-state memories, and optical modulators. Barium titanate, a tetragonal ferroelectric at room temperature, is a prime example of a material both mechanically and optically active. This thesis deals primarily with the deposition of active, oxide-based materials and their integration into device structures where either the mechanical or optical properties are exploited. The technologically interesting paradigms within which these active oxide materials have been investigated are microelectromechanical systems, plasmonics, and metamaterials. Microelectromechanical systems are devices that have been micromachined and rely on an applied voltage to induce a mechanical response. Mechanically active materials, such as piezoelectrics or ferroelectrics, can increase the response of these devices. Plasmonics deals with electromagnetic waves resonantly coupled into free electron oscillations at a metal-dielectric interface or metal nanoparticle. Coupling to these resonant modes allows surface plasmon polaritons to propagate along the metal with a nonlinear dispersion. Metamaterials are ordered, subwavelength, metal inclusions in a dielectric, which respond collectively to electromagnetic radiation. This response can yield a material permittivity or permeability not found in nature. The optical properties of metamaterials lead to effects such as negative index response and super lensing, and can be used to design optical cloaking structures. Here, devices utilizing these effects are investigated with an eye toward tuning or switching their resonant response using optically active oxide thin films. This manuscript follows the evolution of active oxide thin films from deposition, through design of plasmonic devices and active metamaterials, finite difference modeling of these structures, and finally experimental validation. First, deposition and material integration techniques for oxide-based thin films will be discussed. The role of molecular beam epitaxy, pulsed laser deposition, and ion beam assisted deposition as material growth techniques are investigated. Development of a multitude of oxide materials using these techniques including barium titanate, strontium ruthenate, vanadium oxide, and magnesium oxide will be covered. The following two sections deal with the mechanical and optical properties of barium titanate thin films as they are studied and utilized to design and fabricate active devices. Films were characterized mechanically, using nanoindentation and piezoresponse force microscopy, and optically with variable angle spectroscopic ellipsometry. The subsequent section deals with the design, fabrication, and experimental validation of an active optical device based on surface plasmon polariton wavevector modulation via electrooptic modulation of a barium titanate thin film. Interferometers based on pairs of parallel slits fabricated in silver films on barium titanate are used to investigate optical modulation due to both domain switching and the electrooptic effect. Finally, active metamaterials are discussed through the investigation of a new material, vanadium oxide, as it is deposited and characterized, and the results used to design and fabricate active, split-ring resonator metamaterial structures.

Dicken, Matthew J.

340

OXIDATIVE TREATMENT OF INDUSTRIAL WASTEWATER  

EPA Science Inventory

This paper defines industrial waste treatment process as falling into categories of oxidative destruction, reductive destruction, and non-destructive, separation operations. The various oxidative approaches, including biological, chemical and thermal methods, are then discussed i...

341

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2013-04-16

342

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2014-05-20

343

Staged membrane oxidation reactor system  

DOEpatents

Ion transport membrane oxidation system comprising (a) two or more membrane oxidation stages, each stage comprising a reactant zone, an oxidant zone, one or more ion transport membranes separating the reactant zone from the oxidant zone, a reactant gas inlet region, a reactant gas outlet region, an oxidant gas inlet region, and an oxidant gas outlet region; (b) an interstage reactant gas flow path disposed between each pair of membrane oxidation stages and adapted to place the reactant gas outlet region of a first stage of the pair in flow communication with the reactant gas inlet region of a second stage of the pair; and (c) one or more reactant interstage feed gas lines, each line being in flow communication with any interstage reactant gas flow path or with the reactant zone of any membrane oxidation stage receiving interstage reactant gas.

Repasky, John Michael; Carolan, Michael Francis; Stein, VanEric Edward; Chen, Christopher Ming-Poh

2012-09-11

344

Experiments with Unusual Oxidation States  

ERIC Educational Resources Information Center

Describes four synthesis experiments, adapted for the general chemistry laboratory, in which compounds in unusual oxidation are prepared. The abnormal oxidation states involved in the synthesis products are: silver (II), chromium (II), lead (IV), and bromine (I). (MLH)

Kauffman, G. B.

1975-01-01

345

ChemTeacher: Oxidation States  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Oxidation States page includes resources for teaching students about determining oxidation states of atoms within compounds.

2012-07-24

346

Oxidative phosphorylation revisited.  

PubMed

The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic explanation for the energy coupling and ATP synthesis carried out in mitochondria and chloroplast thylakoids. The mechanism does not suffer from the flaws in Mitchell's chemiosmotic theory that have been pointed out in many studies since its first appearance 50 years ago, when it was hailed as a ground-breaking mechanistic explanation of what is perhaps the most important process in cellular energetics. The new findings fit very well with the predictions of Nath's torsional mechanism of energy transduction and ATP synthesis. It is argued that this mechanism, based on at least 15 years of experimental and theoretical work by Sunil Nath, constitutes a fundamentally different theory of the energy conversion process that eliminates all the inconsistencies in Mitchell's chemiosmotic theory pointed out by other authors. It is concluded that the energy-transducing complexes in oxidative phosphorylation and photosynthesis are proton-dicarboxylic acid anion cotransporters and not simply electrogenic proton translocators. These results necessitate revision of previous theories of biological energy transduction, coupling, and ATP synthesis. The novel molecular mechanism is extended to cover ATP synthesis in prokaryotes, in particular to alkaliphilic and haloalkaliphilic bacteria, essentially making it a complete theory addressing mechanistic, kinetic, and thermodynamic details. Finally, based on the new interpretation of oxidative phosphorylation, quantitative values for the P/O ratio, the amount of ATP generated per redox package of the reduced substrates, are calculated and compared with experimental values for fermentation on different substrates. It is our hope that the presentation of oxidative phosphorylation and photophosphorylation from a wholly new perspective will rekindle scientific discussion of a key process in bioenergetics and catalyze new avenues of research in a truly interdisciplinary field. PMID:25384602

Nath, Sunil; Villadsen, John

2015-03-01

347

ADVANCED OXIDATION PROCESS  

SciTech Connect

The design of new, high efficiency and cleaner burning engines is strongly coupled with the removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from fuels. Oxidative desulfurization (ODS) wherein these dibenzothiophene derivatives are oxidized to their corresponding sulfoxides and sulfones is an approach that has gained significant attention. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) convert in a catalytic process dibenzothiophene and its derivatives to the corresponding sulfoxides and sulfones rapidly at moderate temperatures (60 C) and ambient pressure. The reaction can be performed in both an aqueous system containing an alcohol (methanol, ethanol, or t-butanol) to solubilize the DBT and in a two-phase hydrocarbon/aqueous system where the alcohol is present in both phases and facilitates the oxidation. Under a consistent set of conditions using the FeBF{sub 2} TAML activator, the degree of conversion was found to be t-butanol > methanol > ethanol. In the cases of methanol and ethanol, both the sulfoxide and sulfone were observed while for t-butanol only the sulfone was detected. In the two-phase system, the alcohol may function as an inverse phase transfer agent. The oxidation was carried out using two different TAML activators. In homogeneous solution, approximately 90% oxidation of the DBT could be achieved using the prototype TAML activator, FeB*, by sonicating the solution at near room temperature. In bi-phasic systems conversions as high as 50% were achieved using the FeB* TAML activator and hydrogen peroxide at 100 C. The sonication method yielded only {approx}6% conversion but this may have been due to mixing.

Colin P. Horwitz; Terrence J. Collins

2003-10-22

348

REVIEW OF PLUTONIUM OXIDATION LITERATURE  

SciTech Connect

A brief review of plutonium oxidation literature was conducted. The purpose of the review was to ascertain the effect of oxidation conditions on oxide morphology to support the design and operation of the PDCF direct metal oxidation (DMO) furnace. The interest in the review was due to a new furnace design that resulted in oxide characteristics that are different than those of the original furnace. Very little of the published literature is directly relevant to the DMO furnace operation, which makes assimilation of the literature data with operating conditions and data a convoluted task. The oxidation behavior can be distilled into three regimes, a low temperature regime (RT to 350 C) with a relatively slow oxidation rate that is influenced by moisture, a moderate temperature regime (350-450 C) that is temperature dependent and relies on more or less conventional oxidation growth of a partially protective oxide scale, and high temperature oxidation (> 500 C) where the metal autocatalytically combusts and oxidizes. The particle sizes obtained from these three regimes vary with the finest being from the lowest temperature. It is surmised that the slow growth rate permits significant stress levels to be achieved that help break up the oxides. The intermediate temperatures result in a fairly compact scale that is partially protective and that grows to critical thickness prior to fracturing. The growth rate in this regime may be parabolic or paralinear, depending on the oxidation time and consequently the oxide thickness. The high temperature oxidation is invariant in quiescent or nearly quiescent conditions due to gas blanketing while it accelerates with temperature under flowing conditions. The oxide morphology will generally consist of fine particles (<15 {micro}m), moderately sized particles (15 < x < 250 {micro}m) and large particles (> 250 {micro}m). The particle size ratio is expected to be < 5%, 25%, and 70% for fine, medium and large particles, respectively, for metal temperatures in the 500-600 C range.

Korinko, P.

2009-11-12

349

Electrochemical Oxidation of 8-Oxoguanine  

Microsoft Academic Search

Abstract Electrochemical oxidation of DNA can occur at each of the four bases and guanine is the one that can suffer the easiest oxidative damage. The occurrence of the guanine oxidation product, 8-oxoguanine, as a consequence of DNA damage caused by DNA oxidation causes important mutagenic,lesions and hence it is very important to develop reliable methods,for its quantification. Electrochemical study

A. M. Oliveira Brett; J. A. P. Piedade; S. H. P. Serrano

2000-01-01

350

Materials Modification in Nanotechnology: Oxidation  

NSDL National Science Digital Library

This PowerPoint created and presented by the Nanotechnology Applications and Career Knowledge (NACK) Center introduces students to oxidation. It goes over the various types of oxide â?? native, gate, field, etc. It discusses dry vs. wet oxidation, high pressure oxidation, chemical vapor deposition and has a section on modifying dielectric constant. This is a great resource for any classroom looking at nanofabrication modifications. This and all other valuable resources from the NACK Center require a fast, easy, free log-in.

351

Lipid oxidation in food emulsions  

Microsoft Academic Search

Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of lipid oxidation in these systems. The oxidation of emulsified lipids differs from that of bulk lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the

John N. Coupland; D. Julian McClements

1996-01-01

352

Neurodegenerative diseases and oxidative stress  

Microsoft Academic Search

Oxidative stress has been implicated in the progression of Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Oxygen is vital for life but is also potentially dangerous, and a complex system of checks and balances exists for utilizing this essential element. Oxidative stress is the result of an imbalance in pro-oxidant\\/antioxidant homeostasis that leads to the generation of toxic reactive

Kevin J. Barnham; Colin L. Masters; Ashley I. Bush

2004-01-01

353

Doped palladium containing oxidation catalysts  

DOEpatents

A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

Mohajeri, Nahid

2014-02-18

354

Choline oxidation and choline dehydrogenase  

Microsoft Academic Search

The oxidation of choline by both freshly prepared and aged rat liver mitochondria is inhibited by amytal. Whereas rotenone inhibits choline-cytochromec reductase only in the case of freshly prepared mitochondria, the extent of inhibition is influenced by preincubation, but the inhibition is not secondary to the inhibited oxidation of betaine aldehyde, the product of choline oxidation. Evidence shows that rotenone

Lin Chi-Shui I; Ru-Dan Wu

1986-01-01

355

21 CFR 184.1545 - Nitrous oxide.  

Code of Federal Regulations, 2014 CFR

... Nitrous oxide. (a) Nitrous oxide (empirical formula N2 O...will support combustion. Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of nitrogen are removed by...

2014-04-01

356

21 CFR 184.1545 - Nitrous oxide.  

Code of Federal Regulations, 2013 CFR

... Nitrous oxide. (a) Nitrous oxide (empirical formula N2 O...will support combustion. Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of nitrogen are removed by...

2013-04-01

357

21 CFR 184.1545 - Nitrous oxide.  

Code of Federal Regulations, 2011 CFR

... Nitrous oxide. (a) Nitrous oxide (empirical formula N2 O...will support combustion. Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of nitrogen are removed by...

2011-04-01

358

ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation  

E-print Network

ORIGINAL ARTICLE Sulfur oxidizers dominate carbon fixation at a biogeochemical hot spot in the dark clade of marine gamma-proteobacterial sulfur oxidizers (GSOs) are distributed throughout proteins for sulfur oxidation (adenosine phosphosulfate reductase, sox (sulfur oxidizing system

Hansell, Dennis

359

Microviscosity in Poly(ethylene oxide)-Polypropylene Oxide-Poly(ethylene oxide) Block Copolymers Probed by  

E-print Network

Microviscosity in Poly(ethylene oxide)-Polypropylene Oxide-Poly(ethylene oxide) Block Copolymers 2002; accepted 10 September 2002 ABSTRACT: Triblock copolymers [poly(ethylene oxide) (PEO INTRODUCTION Triblock copolymers of poly(ethylene oxide) (PEO) and polypropylene oxide (PPO) are soluble in wa

Granick, Steve

360

Model catalytic oxidation studies using supported monometallic and heterobimetallic oxides  

SciTech Connect

This research program is directed toward a more fundamental understanding of the effects of catalyst composition and structure on the catalytic properties of metal oxides. Metal oxide catalysts play an important role in many reactions bearing on the chemical aspects of energy processes. Metal oxides are the catalysts for water-gas shift reactions, methanol and higher alcohol synthesis, isosynthesis, selective catalytic reduction of nitric oxides, and oxidation of hydrocarbons. A key limitation to developing insight into how oxides function in catalytic reactions is in not having precise information of the surface composition under reaction conditions. To address this problem we have prepared oxide systems that can be used to study cation-cation effects and the role of bridging (-O-) and/or terminal (=O) surface oxygen anion ligands in a systematic fashion. Since many oxide catalyst systems involve mixtures of oxides, we selected a model system that would permit us to examine the role of each cation separately and in pairwise combinations. Organometallic molybdenum and tungsten complexes were proposed for use, to prepare model systems consisting of isolated monomeric cations, isolated monometallic dimers and isolated bimetallic dimers supported on silica and alumina. The monometallic and bimetallic dimers were to be used as models of more complex mixed- oxide catalysts. Our current program was to develop the systems and use them in model oxidation reactions.

Ekerdt, J.G.

1992-02-03

361

Wet vs. Dry Oxidation Processes  

NSDL National Science Digital Library

In this YouTube video, created by Southwest Center for Microsystems Education (SCME), viewers can watch an animation on the the difference between wet and dry thermal oxidation processes. This animation "shows a side by side comparison of a wet oxidation process vs. a dry oxidation process. Both processes use an oxygen source to grow silicon dioxide (SiO2) on a silicon wafer heated furnace. Wet thermal oxidation uses water vapor. Dry thermal oxidation uses oxygen gas." Viewers can learn more on this topic in the Deposition Overview for MEMS Learning Module which can be found on the SCME website along with supplementary materials. 

362

Oxidation in a temperature gradient  

SciTech Connect

The effects of a temperature gradient and heat flux on point defect diffusion in protective oxide scales were examined. Irreversible thermodynamics were used to expand Fick's first law of diffusion to include a heat flux term--a Soret effect. Oxidation kinetics were developed for the oxidation of cobalt and for nickel doped with chromium. Research in progress is described to verify the effects of a heat flux by oxidizing pure cobalt in a temperature gradient above 800 C, and comparing the kinetics to isothermal oxidation. The tests are being carried out in the new high temperature gaseous corrosion and corrosion/erosion facility at the Albany Research Center.

Holcomb, Gordon R.; Covino, Bernard S., Jr.; Russell, James H.

2001-01-01

363

Oxidized Phosphatidylserine: Production and Bioactivities  

PubMed Central

Recent development of analytical methods for lipid hydroperoxides and preparation of highly pure lipid hydroperoxides have revealed the important new pathophysiological roles of oxidized phospholipids. Generation of reactive oxygen species and subsequent oxidative stress leads to random oxidation of membrane phospholipids. However, recent studies have reported that anionic phospholipid molecules such as phosphatidylserine (PS) and cardiolipin are preferentially oxidized during apoptosis, resulting in efficient apoptosis execution and apoptotic cell clearance by phagocytes. This review is exclusively focused on selective production of oxidized PS (oxPS) during apoptosis as well as the novel roles of oxPS under pathophysiological conditions.

Matsura, Tatsuya

2014-01-01

364

The oxidative dehydrogenation of ethane with nitrous oxide by molybdenum oxide supported by silica gel  

E-print Network

be realized by consideration of less conventional oxidants. The patent literature discloses a number of reactions where SO2 has been used as the oxidant. Over chromia-alumina, S02 has been used as the oxidant to produce isobutylene from isobutane (4...

Ward, Mark Branham

1977-01-01

365

Production of microspheres of thorium oxide, uranium oxide and plutonium oxide and their mixtures containing carbon  

Microsoft Academic Search

A process is desclosed for the production of microspheres of thorium oxide, uranium oxide or plutonium oxide and mixtures thereof, containing carbon. The microspheres are prepared by first forming an aqueous alkaline solution of a salt of said metals which will precipitate to a solid form in a concentrated alkaline medium together with an alkaline polymerizable organic monomer and carbon,

G. Bezzi; A. Facchini; G. Martignani; M. Pastore

1980-01-01

366

Infrared transparent conductive oxides  

NASA Astrophysics Data System (ADS)

A novel class of complex metal oxides that have potential as transparent conducting oxides (TCOs) for the electromagnetic-interference (EMI) shielding on IR-seeker windows and missile domes has been identified. These complex metal oxides exhibit the rhombohedral (R3m) crystalline structure of naturally occurring delafossite, CuFeO2. The general chemical formula is ABO2 where A is a monovalent metal (Me+1 such as Cu, Ag, Au, Pt or Pd, and B is a trivalent metal (Me3+) such as Al,Ti,Cr,Co,Fe,Ni,Cs,Rh,Ga,Sn,In,Y,La,Pr,Nd,Sm or Eu. By adjusting the oxygen content, the conductivity can be varied over a wide range so that the delafossites behave as insulators, semiconductors or metals. This paper presents results for films of p-type CuxAlyOz and n-type CuxCryOz deposited by reactive magnetron co-sputtering from high-purity-metal targets. Films have been deposited using conventional RF- and DC-power supplies, and a new asymmetric-bipolar-pulsed- DC-power supply. Similar to the high-temperature-copper- oxide superconductors, the presence of Cu-O bonds is critical for the unique properties. Fourier transform infrared (FTIR) and electron spectroscopy for chemical analysis (ESCA) are used to understand the relationship between the optoelectornic properties and the molecular structure of the films. For example, FTIR absorption bands at 1470 and 1395cm-1 are present only in CuxAlyOz films that exhibit enhanced electrical conductivity. When these bands are absent, the CuxAlyOz films have high values of resistivity. In addition to the 1470 and 1395cm-1 bands observed in CuxAlyOz films, another pair of bands at 1040 and 970cm-1 is present in CuxCryOz films.

Johnson, Linda F.; Moran, Mark B.

2001-09-01

367

Ultra supercritical steamside oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections.

Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Ziomek-Moroz, Margaret

2005-01-01

368

Transparent Conducting Oxides  

Microsoft Academic Search

In the interim between the conception of this issue of MRS Bulletin on transpar- ent conducting oxides (TCOs) and its pub- lication, the remarkable applications dependent on these materials have contin- ued to make sweeping strides. These in- clude the advent of larger flat-screen high-definition televisions (HDTVs), larger and higher-resolution screens on portable computers, the increasing importance of low emissivity

David S. Ginley

369

Oxidative neuronal injury  

PubMed Central

The extracellular signal regulated protein kinases (ERK1/2) are essential for normal development and functional plasticity of the central nervous system. However, a growing number of recent studies in models of cerebral ischemia, brain trauma and neurodegenerative diseases implicate a detrimental role for ERK1/2 signaling during oxidative neuronal injury. Neurons undergoing oxidative stress-related injuries typically display a biphasic or sustained pattern of ERK1/2 activation. A variety of potential targets of reactive oxygen species and reactive nitrogen species could contribute to ERK1/2 activation. These include cell surface receptors, G proteins, upstream kinases, protein phosphatases and proteasome components, each of which could be direct or indirect targets of reactive oxygen or nitrogen species, thereby modulating the duration and magnitude of ERK1/2 activation. Neuronal oxidative stress also appears to influence the subcellular trafficking and/or localization of activated ERK1/2. Differences in compartmentalization of phosphorylated ERK1/2 have been observed in diseased or injured human neurons and in their respective animal and cell culture model systems. We propose that differential accessibility of ERK1/2 to downstream targets, which is dictated by the persistent activation of ERK1/2 within distinct subcellular compartments, underlies the neurotoxic responses that are driven by this kinase. PMID:15153095

Chu, Charleen T.; Levinthal, David J.; Kulich, Scott M.; Chalovich, Elisabeth M.; DeFranco, Donald B.

2007-01-01

370

Magnetoplumbite-related oxides  

SciTech Connect

These ferrites were prepared from Fe{sub 2}O{sub 3}, MO oxides (M = Ba,Sr,Pb) and MeO oxides (Me = Mg,Mn,Co,Zn). Chemical compositions of the main barium ferrites (M = Ba) are represented in a ternary diagram. The structures of these various compounds (M,Y,W,Z,X,U) are closely related. The simplest one is the compound BaFe{sub 12}O{sub 19} (M). Its crystal structure is similar to that of the mineral magnetoplumbite PbFe{sub 7.5}Mn{sub 3.5}Al{sub 0.5}O{sub 19} (PbM{sub 12}O{sub 19}) (5). For this reason the hexagonal ferrites are also known as magnetoplumbite-type ferrites (called MP-type in this paper). When the Fe{sup 3+} ions are replaced by other trivalent ions, such as Al{sup 3+}, Ga{sup 3+}, another group of MP-type oxides, namely AB{sub 12}O{sub 19} (A = Ba{sup 2+} or a large divalent ion; B = Al{sup 3+} or Ga{sup 3+}) is obtained. In this paper, the authors briefly review ideal structure and major properties and uses, especially in the case of ferrites.

Collongues, R.; Gourier, D.; Kahn-Harari, A.; Lejus, A.M.; Thery, J.; Vivien, D. (Lab. de Chimie Appliquee de l'Etat Solide, Ecole National Superieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75005 Paris (FR))

1990-01-01

371

Nonisostructural complex oxide heteroepitaxy  

SciTech Connect

The authors present an overview of the fundamentals and representative examples of the growth of epitaxial complex oxide thin films on structurally dissimilar substrates. The authors will delineate how the details of particular crystal structures and symmetry of different oxide surfaces can be employed for a rational approach to the synthesis of nonisostructural epitaxial heterostructures. The concept of oxygen eutaxy can be widely applied. Materials combinations will be split into three categories, and in all cases the films and substrates occur in different crystal structures: (1) common translational and rotational symmetry between the film and substrate planes; (2) translational symmetry mismatch between the substrates and films that is distinct from a simple mismatch in lattice parameters; and (3) rotational symmetry mismatch. In case (1), in principle single-crystalline thin films can be attained despite the films and substrates possessing different crystal structures. In case (2), antiphase boundaries will be prevalent in the thin films. In case (3), thin-film rotational variants that are joined by tilt boundaries will be present. Diffraction techniques to determine crystallographic alignment and epitaxial variants are discussed, and transmission electron microscopy studies to investigate extended defects in the thin films will also be reviewed. The authors end with open problems in this field regarding the structure of oxide interfaces that can be topics for future research.

Wong, Franklin J., E-mail: fwong@seas.harvard.edu; Ramanathan, Shriram [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)

2014-07-01

372

The role of oxidative debris on graphene oxide films.  

PubMed

We study the effect of oxidative impurities on the properties of graphene oxide and on the graphene oxide Langmuir-Blodgett films (LB). The starting material was grupo Antolín nanofibers (GANF) and the oxidation process was a modified Hummers method to obtain highly oxidized graphene oxide. The purification procedure reported in this work eliminated oxidative impurities decreasing the thickness of the nanoplatelets. The purified material thus obtained presents an oxidation degree similar to that achieved by chemical reduction of the graphite oxide. The purified and non-purified graphene oxides were deposited onto silicon by means of a Langmuir-Blodgett (LB) methodology. The morphology of the LB films was analyzed by field emission scanning microscopy (FE-SEM) and micro-Raman spectroscopy. Our results show that the LB films built by transferring Langmuir monolayers at the liquid-expanded state of the purified material are constituted by close-packed and non-overlapped nanoplatelets. The isotherms of the Langmuir monolayer precursor of the LB films were interpreted according to the Volmer's model. PMID:24166869

López-Díaz, David; Velázquez, Maria Mercedes; Blanco de La Torre, Santiago; Pérez-Pisonero, Ana; Trujillano, Raquel; García Fierro, José Luis; Claramunt, Sergi; Cirera, Albert

2013-12-01

373

Solid Oxide Fuel Cells  

SciTech Connect

Solid oxide fuel cell (SOFC) technology, which offers many advantages over traditional energy conversion systems including low emission and high efficiency, has become increasingly attractive to the utility, automotive, and defense industries (as shown in Figure 1). As an all solid-state energy conversion device, the SOFC operates at high temperatures (700-1,000 C) and produces electricity by electrochemically combining the fuel and oxidant gases across an ionically conducting oxide membrane. To build up a useful voltage, a number of cells or PENs (Positive cathode-Electrolyte-Negative anode) are electrically connected in series in a stack through bi-polar plates, also known as interconnects. Shown in Figure 2 (a) is a schematic of the repeat unit for a planar stack, which is expected to be a mechanically robust, high power-density and cost-effective design. In the stack (refer to Figure 2 (b)), the interconnect is simultaneously exposed to both an oxidizing (air) environment on the cathode side and a reducing (fuels such as hydrogen or natural gas) environment on the anode side for thousands of hours at elevated temperatures (700-1,000 C). Other challenges include the fact that water vapor is likely to be present in both of these environments, and the fuel is likely to contain sulfide impurities. Also, the interconnect must be stable towards any sealing materials with which it is in contact, under numerous thermal cycles. Furthermore, the interconnect must also be stable towards electrical contact materials that are employed to minimize interfacial contact resistance, and/or the electrode materials. Considering these service environments, the interconnect materials should possess the following properties: (1) Good surface stability (resistance to oxidation and corrosion) in both cathodic (oxidizing) and anodic (reducing) atmospheres. (2) Thermal expansion matching to the ceramic PEN and other adjacent components, all of which typically have a coefficient of thermal expansion (CTE) in the range of 10.5-12.0 x 10{sup -6} K{sup -1}. (3) High electrical conductivity through both the bulk material and in-situ formed oxide scales. (4) Satisfactory bulk and interfacial mechanical/thermomechanical reliability and durability at the SOFC operating temperatures. (5) Good compatibility with other materials in contact with interconnects such as seals and electrical contact materials. Until recently, the leading candidate material for the interconnect was doped lanthanum chromite (LaCrO3), which is a ceramic material which can easily withstand the traditional 1000 C operating temperature. However, the high cost of raw materials and fabrication, difficulties in obtaining high-density chromite parts at reasonable sintering temperatures, and the tendency of the chromite interconnect to partially reduce at the fuel gas/interconnect interface, causing the component to warp and the peripheral seal to break, have plagued the commercialization of planar SOFCs for years. The recent trend in developing lower temperature, more cost-effective cells which utilize anode-supported, several micron-thin electrolytes and/or new electrolytes with improved conductivity make it feasible for lanthanum chromite to be supplanted by metals or alloys as the interconnect materials. Compared to doped lanthanum chromite, metals or alloys offer significantly lower raw material and fabrication costs.

Yang, Z Gary; Stevenson, Jeffry W.; Singh, Prabhakar

2003-06-15

374

Hysteresis-free high rate reactive sputtering of niobium oxide, tantalum oxide, and aluminum oxide  

SciTech Connect

This work reports on experimental studies of reactive sputtering from targets consisting of a metal and its oxide. The composition of the targets varied from pure metal to pure oxide of Al, Ta, and Nb. This combines features from both the metal target and oxide target in reactive sputtering. If a certain relation between the metal and oxide parts is chosen, it may be possible to obtain a high deposition rate, due to the metal part, and a hysteresis-free process, due to the oxide part. The aim of this work is to quantify the achievable boost in oxide deposition rate from a hysteresis-free process by using a target consisting of segments of a metal and its oxide. Such an increase has been previously demonstrated for Ti using a homogeneous substoichiometric target. The achievable gain in deposition rate depends on transformation mechanisms from oxide to suboxides due to preferential sputtering of oxygen. Such mechanisms are different for different materials and the achievable gain is therefore material dependent. For the investigated materials, the authors have demonstrated oxide deposition rates that are 1.5–10 times higher than what is possible from metal targets in compound mode. However, although the principle is demonstrated for oxides of Al, Ta, and Nb, a similar behavior is expected for most oxides.

Särhammar, Erik, E-mail: erik.sarhammar@angstrom.uu.se; Berg, Sören; Nyberg, Tomas [Department of Solid State Electronics, The Ångström Laboratory, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden)

2014-07-01

375

The competing oxide and sub-oxide formation in metal-oxide molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

The hetero-epitaxial growth of the n-type semiconducting oxides ?-Ga2O3, In2O3, and SnO2 on c- and r-plane sapphire was performed by plasma-assisted molecular beam epitaxy. The growth-rate and desorbing flux from the substrate were measured in-situ under various oxygen to metal ratios by laser reflectometry and quadrupole mass spectrometry, respectively. These measurements clarified the role of volatile sub-oxide formation (Ga2O, In2O, and SnO) during growth, the sub-oxide stoichiometry, and the efficiency of oxide formation for the three oxides. As a result, the formation of the sub-oxides decreased the growth-rate under metal-rich growth conditions and resulted in etching of the oxide film by supplying only metal flux. The flux ratio for the exclusive formation of the sub-oxide (e.g., the p-type semiconductor SnO) was determined, and the efficiency of oxide formation was found to be the highest for SnO2, somewhat lower for In2O3, and the lowest for Ga2O3. Our findings can be generalized to further oxides that possess related sub-oxides.

Vogt, Patrick; Bierwagen, Oliver

2015-02-01

376

Iridium oxide-polymer nanocomposite electrode materials for water oxidation.  

PubMed

Nanocomposite anode materials for water oxidation have been readily synthesized by electrodeposition of iridium oxide nanoparticles into poly(pyrrole-alkylammonium) films, previously deposited onto carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. The nanocomposite films were characterized by electrochemistry, transmission electron microscopy, and atomic force microscopy. They showed an efficient electrocatalytic activity toward the oxygen evolution reaction. Data from Tafel plots have demonstrated that the catalytic activity of the iridium oxide nanoparticles is maintained following their inclusion in the polymer matrix. Bulk electrolysis of water at carbon foam modified electrodes have shown that the iridium oxide-polymer composite presents a higher catalytic activity and a better operational stability than regular oxide films. PMID:25045786

Lattach, Youssef; Rivera, Juan Francisco; Bamine, Tahya; Deronzier, Alain; Moutet, Jean-Claude

2014-08-13

377

Oxidative Denitrogenation of Coal Liquids  

NASA Astrophysics Data System (ADS)

The oxidative denitrogenation of quinoline (as a model compound representing the nitrogen containing structure of coal liquids) has been investigated in two steps: oxidation by perdecanoic acid at 50 °C to produce quinoline N-oxide in order to weaken the nitrogen-carbon bond; thermal decomposition of quinoline N-oxide to remove nitrogen as its respective oxides. Quinoline is successfully converted to quinoline N-oxide in the oxidation step. Thermal decomposition of quinoline N-oxide at 400 °C and 600 kPa of N2 produces 52-wt% quinoline, 22-wt% a condensed polymeric compound and 26-wt% gaseous mixture of CO2, CO and O2. Almost all the nitrogen content of quinoline N-oxide has remained in the residue of decomposition reaction. This confirms that thermal decomposition not only fails to remove nitrogen from structure of the oxidized molecule, but it also leads to production of a more complex aromatic structure with 10.4-wt% nitrogen content, compared to 10.6-wt% nitrogen content of quinoline.

Mirshamsi, Sepideh

378

Wet oxidation catalyzed by ruthenium supported on cerium (IV) oxides  

Microsoft Academic Search

The activity of precious meta catalysts in the wet oxidation of organic compounds was investigated. Ruthenium was the most active catalyst among the precious metals examined, and cerium (IV) oxide was the most effective support. The Ru\\/Ce catalyst rivaled homogeneous copper catalyst, which is used in the practical wastewater treatment, for the oxidation of n-propyl alcohol, n-butyl alcohol, phenol, acetamide,

Seiichiro Imamura; Ikumi Fukuda; Shingo Ishida

1988-01-01

379

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

Dunning, John S.; Alman, David E.

2002-11-05

380

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOEpatents

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

2002-11-05

381

Student Nitric Oxide Explorer  

NASA Astrophysics Data System (ADS)

The Student Nitric Oxide Explorer (SNOE) is a small scientific spacecraft designed to launch on a PegasusTM XL vehicle for the Student Explorer Demonstration Initiative. Its scientific goals are to measure nitric oxide density in the lower thermosphere and to analyze the solar and magnetospheric influences that create it and cause its abundance to vary dramatically. The SNOE ('snowy') spacecraft and instrumentation is being designed and built at the University of Colorado Laboratory for Atmospheric and Space Physics (LASP) by a team of scientists, engineers, and students. The spacecraft is a compact hexagonal structure, 37' by 39', weighing approximately 280 lbs. It will be launched into a circular orbit, 550 km altitude, 97.5 degrees inclination for sun-synchronous precession at 10:30 AM ascending node. It is designed to spin at 5 rpm with the spin axis normal to the orbit plane. It carries three instruments: an ultraviolet spectrometer to measure nitric oxide altitude profiles on the limb, a two-channel ultraviolet photometer to measure auroral emissions in the nadir, and a five-channel solar soft x-ray photometer. An experimental GPS receiver is also included. The spacecraft structure is aluminum, with a center platform section for the instruments and subsystems. Static solar arrays are supported by a truss system. A spacecraft microprocessor handles all subsystem, instrument, and communications functions in an integrated fashion, including command decoding, attitude control, instrument commanding, data storage, and telemetry. The spacecraft is scheduled for launch in early 1997 and will be operated by students at LASP. For more information on the SNOE project, please visit http://lasp.colorado.edu/snoe/.

Solomon, Stanley C.; Barth, Charles A.; Axelrad, Penina; Bailey, Scott M.; Brown, Ronald; Davis, Randal L.; Holden, Timothy E.; Kohnert, Richard A.; Lacy, Frederick W.; McGrath, Michael T.; O'Connor, Darren C.; Perich, Jeffrey P.; Reed, Heather L.; Salada, Mark A.; Simpson, John; Srinivasan, Jeffrey M.; Stafford, George A.; Steg, Stephen R.; Tate, Gail A.; Westfall, James C.; White, Neil R.; Withnell, Peter R.; Woods, Thomas N.

1996-10-01

382

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors are described that include doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-07-27

383

Complex oxide interface studies  

NASA Astrophysics Data System (ADS)

As the proximity and complexity increase for modern device structures, it becomes increasingly important to be able to understand film growth and interface properties of the new classes of complex (stoichiometry and structure) thin films in heterostructures. Non-destructive in situ real-time surface analytical techniques with monolayer surface specificity and ability to provide information for complete characterization would be ideal for studying the complex materials. Therefore, the primary objective of this research is to develop a methodology for in situ real-time characterization of complex oxide thin films during deposition or under processing conditions; as well as to demonstrate the application of the developed system. To this end, a surface analysis system incorporating spectroscopy ellipsometry (SE) and ion scattering and recoil spectroscopy (ISARS) with differentially pumped ion beam and detector lines has been integrated with a reactive ion beam deposition system. This integrated system permits the characterization of optical properties, film thickness, surface composition and thin film structure during film growth under moderate background pressures. In the first part of this research, the oxygen transport process in c-axis oriented YBa2Cu3O7--delta thin films was investigated in real-time during the deposition and postdeposition oxidation using in situ SE. Two transport regimes dominated by oxygen out- and in-diffusion have been observed during deposition process. The effect of oxygen partial pressure on the extent of oxidation of as-deposited films has been studied during postdeposition cooling. The temperature dependence of the dielectric functions of oxygen deficient YBa2Cu3O6 films has been modeled using Lorentz oscillators. The high dielectric constant material (Ba0.5, Sr0.5)TiO 3 (BST) thin films deposited on various substrates including MgO,Si, SiO2 and Ir have been investigated in the second part of this research. The optical constants of the BST films have been determined. The interface reactions in BST/Si and BST/SiO2/Si structures were elucidated from SE analysis and Auger electron spectroscopy depth profiles. Subcutaneous oxidation in the BST/Ir structure was observed during deposition and postdeposition annealing. The thermal stability of the Ir/TiN/SiO2/Si structure was studied and failure of TiN diffusion barrier layer was suggested from the detection of Ti on the surface by time of flight mass spectroscopy of recoiled ions (ToF-MSRI).

Gao, Ying

2000-10-01

384

Multipod zinc oxide nanowhiskers  

NASA Astrophysics Data System (ADS)

Zinc oxide nanowhiskers with multipod structures have been fabricated on copper-coated Si wafer by sintering the mixture of ZnO and graphite powders in air. The multipod nanowhisker shows tetrapod, tripod and hexapod morphologies with legs of 100-500 nm in diameter and several microns in length. The legs of the multipod nanowhisker intercross at a central knot of the whisker. The octahedron twin nucleus is responsible for the tetrapod structure and possibly responsible for the tripod structure as well. The hexapod structure is due to a stacked nucleus of two octahedron nuclei.

Xu, C. X.; Sun, X. W.

2005-04-01

385

Nitrogen Oxide Calculator  

NSDL National Science Digital Library

In this activity, students will analyze their nitrogen oxide emissions from all sources (including coal-fired power plants, natural gas combustion, gas-powered lawnmowers, etc.) and combine them with vehicle emissions calculated in the previous activity (Ground-level Ozone: Your Vehicle) to derive an estimate of total emissions of smog-forming NOx. They will use an online nitrogen calculator and enter values for private transportation, public transportation, heat and power, and number of people living the household to receive the total emissions figure.

Pratte, John

386

Oxidative stress during extracorporeal circulation.  

PubMed

There is an increased oxidative stress response in patients having cardiac surgery, haemodialysis or extracorporeal membrane oxygenation that is related to poorer outcomes and increased mortality. Exposure of the patients' blood to the artificial surfaces of these extracorporeal devices, coupled with inflammatory responses, hyperoxia and the pathophysiological aspects of the underlying illness itself, all contribute to this oxidative stress response. Oxidative stress occurs when there is a disruption of redox signalling and loss of control of redox balance. Ongoing oxidative stress occurring during extracorporeal circulation (ECC) results in damage to lipids, proteins and DNA and contributes to morbidity and mortality. This review discusses reactive species generation and the potential clinical consequences of oxidative stress during ECC as well as provides an overview of some current antioxidant compounds that are available to potentially mitigate the oxidative stress response. PMID:24482384

McDonald, Charles Ian; Fraser, John Francis; Coombes, Jeff S; Fung, Yoke Lin

2014-12-01

387

A germanate transparent conductive oxide  

PubMed Central

Wide bandgap conductors such as In2O3 and ZnO are used as transparent conducting oxides (TCOs). To date, TCOs are realized using post transition metal cations with largely spread s-orbitals such as In3+, Sn4+, Zn2+ and Cd2+. On the other hand, no good electronic conductor has been realized in oxides of Al, Si and Ge. Here we report the conversion of an oxide of Ge into a good electronic conductor by employing the concept of superdegeneracy. We find that cubic SrGeO3, synthesized under high pressure, displays a direct bandgap of 3.5?eV, a carrier mobility of 12?cm2(Vs)?1, and conductivities of 3?Scm?1 (DC) and 400?Scm?1 (optical conductivity). This is the first Ge-based electronic conductive oxide, and expands the family of TCOs from ionic oxides to covalent oxides. PMID:21915112

Mizoguchi, Hiroshi; Kamiya, Toshio; Matsuishi, Satoru; Hosono, Hideo

2011-01-01

388

Oxidative Stress and Liver Injury  

Microsoft Academic Search

\\u000a Oxidative stress and liver injury are strongly associated. Oxidative stress in the liver can be triggered during different\\u000a conditions and by specific etiologies, including hepatotoxins (acetaminophen [1]), viruses (e.g., hepatitis C virus [2]),\\u000a nonalcoholic steatohepatitis (NASH) [3], hepatocellular carcinoma [4], alcoholic liver disease (ALD) [5], ischemia-­reperfusion,\\u000a and liver fibrosis [6]. Oxidative stress is a state of imbalance between the production

Francisco Javier Cubero; Christian Trautwein

389

Occurrence of Oxidatively Modified Proteins  

Microsoft Academic Search

Free radical-mediated injury is believed to play a key role in the pathogenesis of acute pancreatitis (AP). Therefore, oxidative damage of proteins may be an important event in the development of AP. The present study was performed to investigate oxidative protein modification, quantified as 2,4-dinitrophenylhydrazine-reactive protein-carbonyls, during the time course of taurocholate-induced pancreatitis of the rat and to analyze oxidatively

Thomas Reinheckel; Barbara Nedelev; Juliane Prause; Wolfgang Augustin; Hans-Ulrich Schulz; Hans Lippert; Walter Halangk

1998-01-01

390

Cytotoxic properties of salivary oxidants.  

PubMed

Salivary peroxidase and to a lesser extent myeloperoxidase are present in significant concentrations in saliva and catalyze the oxidation of thiocyanate anion (SCN-) by H2O2 to yield the potent oxidants hypothiocyanous acid (HOSCN) and its conjugate base hypothiocyanite anion (OSCN-). The objective of this study was to characterize the cytotoxic potential of peroxidase-generated HOSCN/OSCN- toward human erythrocytes. We found that HOSCN/OSCN- (0.25 mM) generated by the peroxidase-H2O2-SCN- system caused significant hemolysis at pH 6.0 but not at pH 6.5, 7.0, or 7.4. Erythrocyte hemoglobin (OxyHb) was oxidized to methemoglobin (MetHb) at all pH values tested; however, the rate of MetHb formation was dramatically increased at low pH and was not affected by inosine hexaphosphate, suggesting that hemoglobin was oxidized primarily by HOSCN. Concurrent with oxidation of hemoglobin (Hb), there was a pH-dependent consumption of HOSCN/OSCN- with more of the oxidant consumed at pH 6.0 compared with pH 6.5, 7.0, or 7.4. The enhanced oxidation of Hb at acidic pH was not due simply to increased membrane permeability by the uncharged species (HOSCN), since both erythrocyte lysate Hb and purified Hb were oxidized to the same extent at low pH as were intact erythrocytes. It is concluded that both OSCN- and HOSCN enter human erythrocytes where the protonated oxidant (HOSCN) mediates hemolysis and oxidizes OxyHb to MetHb, whereas both HOSCN and OSCN- oxidize glutathione (GSH). These data suggest that the extracellular pH may play an important role in modulating the cytotoxic properties of salivary oxidants. PMID:2154109

Grisham, M B; Ryan, E M

1990-01-01

391

Oxidative Stress in Diabetes Mellitus  

Microsoft Academic Search

\\u000a Diabetes mellitus of either human, or domestic animals is commonly associated to oxidative stress which is mainly involved\\u000a in the onset of many complications such as cataract, neuropathy, vasculopathies, nephropathy and ketoacidosis. The pathogenesis\\u000a of diabetic oxidative stress is a multifactorial process involving glucose auto-oxidation, formation of advanced glycation\\u000a endproducts and activation of polyol, and protein-kinase pathways. Although the presence

Stefano Comazzi

392

Oxidation of lactose with bromine  

Microsoft Academic Search

Oxidation of lactose by bromine in an aqueous buffered solution was conducted as a model experiment to examine the glycosidic linkage cleavage occurring during the oxidation of oligosaccharides and polysaccharides. The resulting oxidation products, after reduction with sodium borodeuteride, were characterized by GLC–MS analyses of the per-O-methyl or per-O-Me3Si derivatives. Most of the products were carboxylic acids, of which lactobionic

Byung Y. Yang; Rex Montgomery

2005-01-01

393

Pyrite oxidation by thermophilic archaebacteria.  

PubMed Central

Three species of thermophilic archaebacteria of the genera Sulfolobus (Sulfolobus acidocaldarius and S. solfataricus) and Acidianus (Acidianus brierleyi) were tested for their ability to oxidize pyrite and to grow autotrophically on pyrite, to explore their potential for use in coal desulfurization. Only A. brierleyi was able to oxidize and grow autotrophically on pyrite. Jarosite was formed during the pyrite oxidation, resulting in the precipitation of sulfate and iron. The medium composition affected the extent of jarosite formation. PMID:2107795

Larsson, L; Olsson, G; Holst, O; Karlsson, H T

1990-01-01

394

Continuous lengths of oxide superconductors  

DOEpatents

A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

Kroeger, Donald M. (Knoxville, TN); List, III, Frederick A. (Andersonville, TN)

2000-01-01

395

Buried oxide layer in silicon  

DOEpatents

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir, TN)

2001-01-01

396

Oxidation of molten copper matte  

NASA Astrophysics Data System (ADS)

An amount of 80 mg of molten copper matte of a pseudo-ternary Cu2S-FeS-Fe system contained in a slender alumina sample tube was oxidized at 1503 and 1533 K in a mixed O2-Ar gas stream and the oxidation path was followed, comparing the overall rate of oxidation with the gaseous diffusion in the sample tube. The following successive reactions were found to be controlled by gas diffusion. Initially, Fe was oxidized to form FeO. After the melt composition reached a pseudo-ternary Cu2S-FeS-FeO system, FeS was oxidized to form FeO. As the amount of FeO increased, Fe3O4 was also formed and subsequently Cu was produced by the oxidation of Cu2S. In the latter stage, the Cu was oxidized, and the final product under the condition of gas diffusion control was composed of Cu2O, Fe3O4, and CuFeO2. On the other hand, the rate of formation of Fe2O3, CuO, and CuFe2O4 was much slower and they were not formed during the oxidation duration where the overall rate of oxidation was controlled by gas diffusion.

Asaki, Z.; Ando, S.; Kondo, Y.

1988-02-01

397

Transparent conducting oxide nanotubes.  

PubMed

Thin film or porous membranes made of hollow, transparent, conducting oxide (TCO) nanotubes, with high chemical stability, functionalized surfaces and large surface areas, can provide an excellent platform for a wide variety of nanostructured photovoltaic, photodetector, photoelectrochemical and photocatalytic devices. While large-bandgap oxide semiconductors offer transparency for incident light (below their nominal bandgap), their low carrier concentration and poor conductivity makes them unsuitable for charge conduction. Moreover, materials with high conductivity have nominally low bandgaps and hence poor light transmittance. Here, we demonstrate thin films and membranes made from TiO2 nanotubes heavily-doped with shallow Niobium (Nb) donors (up to 10%, without phase segregation), using a modified electrochemical anodization process, to fabricate transparent conducting hollow nanotubes. Temperature dependent current-voltage characteristics revealed that TiO2 TCO nanotubes, doped with 10% Nb, show metal-like behavior with resistivity decreasing from 6.5 × 10(-4) ?cm at T = 300 K (compared to 6.5 × 10(-1) ?cm for nominally undoped nanotubes) to 2.2 × 10(-4) ?cm at T = 20 K. Optical properties, studied by reflectance measurements, showed light transmittance up to 90%, within wavelength range 400 nm-1000 nm. Nb doping also improves the field emission properties of TCO nanotubes demonstrating an order of magnitude increase in field-emitter current, compared to undoped samples. PMID:25180635

Alivov, Yahya; Singh, Vivek; Ding, Yuchen; Nagpal, Prashant

2014-09-26

398

Nanoporous silicon oxide memory.  

PubMed

Oxide-based two-terminal resistive random access memory (RRAM) is considered one of the most promising candidates for next-generation nonvolatile memory. We introduce here a new RRAM memory structure employing a nanoporous (NP) silicon oxide (SiOx) material which enables unipolar switching through its internal vertical nanogap. Through the control of the stochastic filament formation at low voltage, the NP SiOx memory exhibited an extremely low electroforming voltage (? 1.6 V) and outstanding performance metrics. These include multibit storage ability (up to 9-bits), a high ON-OFF ratio (up to 10(7) A), a long high-temperature lifetime (? 10(4) s at 100 °C), excellent cycling endurance (? 10(5)), sub-50 ns switching speeds, and low power consumption (? 6 × 10(-5) W/bit). Also provided is the room temperature processability for versatile fabrication without any compliance current being needed during electroforming or switching operations. Taken together, these metrics in NP SiOx RRAM provide a route toward easily accessed nonvolatile memory applications. PMID:24992278

Wang, Gunuk; Yang, Yang; Lee, Jae-Hwang; Abramova, Vera; Fei, Huilong; Ruan, Gedeng; Thomas, Edwin L; Tour, James M

2014-08-13

399

HYDROCARBON OXIDATION OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE  

EPA Science Inventory

Selective oxidation of hydrocarbons is one of the very important and challenging areas in industrial chemistry due to the wide ranging utility of the resulting oxygenates in fine chemical synthesis. Most of the existing processes for their oxidations employ toxic and often stoich...

400

Rare-earth oxide: aluminum oxide for midrange IR devices  

Microsoft Academic Search

Glass and glass fibers formed from rare earth (RE) oxide-aluminum oxide compositions (REAlTM glasses) have properties similar to sapphire. They exhibit infrared transmission to wavelengths ~ 5000 nm; are hard and strong, thermally stable to ~ 1000°C, highly resistant to attack by aqueous solutions; and can be made into homogeneous products that contain large concentrations of optically active dopants. This

Richard Weber; Ronald W. Waynant; Ilko K. Ilev; Thomas Key; Paul Nordine

2003-01-01

401

Catalysis by Thin Oxide Films and Oxide Nanoparticles  

NASA Astrophysics Data System (ADS)

Model systems for transition and noble metal oxide catalysts, either as thin films or nanoparticles, were prepared by vacuum-deposition of oxides or oxidation of metals (particles, thin films, single crystals). These systems, including Ga2O3, In2O3, V2O3, V2O5, Nb2O5, Pd5O4 and PdO, are well suited for atomic scale characterization by surface-specific methods and for catalytic tests. Investigations of structure and composition were carried out by HRTEM, AFM, STM, SAED, LEED, EDX, XPS and DFT. In many cases, the surface structure of oxides does not coincide with truncations of the known bulk structures. The adsorption properties of the oxide models, in particular those of defects such as oxygen vacancies or step edges, were examined by vibrational spectroscopy (FTIR and SFG) and thermal desorption spectroscopy (TPD) of probe molecules (CO, H2, propane and propene). Together with XPS, quantification of surface coverage was performed. The catalytic activity and selectivity of the model oxides at (near) ambient gas pressure were investigated by microreactor studies of methanol steam reforming (MSR), (inverse) water gas shift (WGS) and CO oxidation. The structural/compositional flexibility of oxides leads to significant challenges in their characterization but also imparts them with exceptional catalytic properties.

Rupprechter, Günther; Penner, Simon

402

Mechanistic Aspects of Pyrite Oxidation in an Oxidizing Gaseous  

E-print Network

Mechanistic Aspects of Pyrite Oxidation in an Oxidizing Gaseous Environment: An in Situ HATR Science, Stony Brook University, Stony Brook, New York 11794-2100 The reaction of FeS2 (pyrite orbital/density functional theory calculations of sulfate-iron hydroxide clusters. Reaction of pyrite

Sparks, Donald L.

403

Oxidation of DOPAC by nitric oxide: effect of superoxide dismutase  

Microsoft Academic Search

This study aimed to characterize the redox interaction between 3,4-dihydroxyphenylacetic acid (DOPAC) and nitric oxide (ÆNO), and to assess the reductive and oxidative decay pathways of the DOPAC semiquinone originating from this interaction. The reaction between DOPAC and ÆNO led to the formation of the DOPAC semiquinone radical, detected by electron paramagnetic resonance (EPR) and stabilized by Mg2+, and the

Joao Laranjinha; Enrique Cadenas

2002-01-01

404

Catalytic water oxidation: Rugged water-oxidation anodes  

Microsoft Academic Search

The efficient catalytic oxidation of water to dioxygen in the solid state is one of the challenges to be overcome to build sun-driven and\\/or electrocatalytic water-splitting devices. Now, an effective water-oxidation hybrid catalyst system has been made by attaching a ruthenium-polyoxometallate complex to a carbon nanotube.

Antoni Llobet

2010-01-01

405

Oxidants, oxidative stress and the biology of ageing  

Microsoft Academic Search

Living in an oxygenated environment has required the evolution of effective cellular strategies to detect and detoxify metabolites of molecular oxygen known as reactive oxygen species. Here we review evidence that the appropriate and inappropriate production of oxidants, together with the ability of organisms to respond to oxidative stress, is intricately connected to ageing and life span.

Toren Finkel; Nikki J. Holbrook

2000-01-01

406

Operation of staged membrane oxidation reactor systems  

DOEpatents

A method of operating a multi-stage ion transport membrane oxidation system. The method comprises providing a multi-stage ion transport membrane oxidation system with at least a first membrane oxidation stage and a second membrane oxidation stage, operating the ion transport membrane oxidation system at operating conditions including a characteristic temperature of the first membrane oxidation stage and a characteristic temperature of the second membrane oxidation stage; and controlling the production capacity and/or the product quality by changing the characteristic temperature of the first membrane oxidation stage and/or changing the characteristic temperature of the second membrane oxidation stage.

Repasky, John Michael

2012-10-16

407

Vacancy coalescence during oxidation of iron nanoparticles  

Microsoft Academic Search

In the present work, we analyze the geometry and composition of the nanostructures obtained from the oxidation of iron nanoparticles. The initial oxidation of iron takes place by outward diffusion of cations through the growing oxide shell. This net material flow is balanced by an opposite flow of vacancies, which coalesce at the metal\\/oxide interface. Thus, the partial oxidation of

Andreu Cabot; Victor F. Puntes; Elena Shevchenko; Yadong Yin; Lluis Balcells; Matthew A. Markus; Steven M. Hughes; A. Paul Alivisatos

2007-01-01

408

Ceramic oxide powders and the formation thereof  

DOEpatents

Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

Katz, J.L.; Chenghung Hung.

1993-12-07

409

Thermal oxidation of single crystalline aluminum nitride  

Microsoft Academic Search

Dry thermal oxidation of low defect density aluminum nitride single crystals was investigated by high resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). Oxidation at 800 °C produced an amorphous oxide layer. In the AlN near the interface were many dislocations, stacking faults and domain boundaries, molecular nitrogen and oxygen. Oxidation at 1000 °C produced a crystalline, epitaxial oxide

J.. Chaudhuri; L. Nyakiti; R. G. Lee; Z. Gu; J. H. Edgar; J. G. Wen

2007-01-01

410

Iridium-tin mixed oxide anode coatings  

Microsoft Academic Search

Mixed oxide coatings of tin and iridium oxide on titanium substrates have been studied over the composition range of 5 to 100 mol % iridium oxide. While stannic oxide behaves as a simple diluent for the electrocatalytically active precious metal oxide, substantial replacement of iridium by tin may be made with little degradation of coating performance in oxygen evolution.

E. N. Balko; P. H. Nguyen

1991-01-01

411

Gate oxide integrity by initial gate current  

Microsoft Academic Search

A new and accurate approach to gate oxide reliability measurements for the determination of the gate oxide quality and lifetime estimation on MOSFET is presented. An accurate gate oxide thickness calculation by gate current provides oxide thickness variations better than conventional CV measurement. A gate oxide quality by gate current analysis is well correlated to the time dependent dielectric breakdown

J. Kang; B. So; D. Baek

2009-01-01

412

High temperature oxidation resistant cermet compositions  

NASA Technical Reports Server (NTRS)

Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

Phillips, W. M. (inventor)

1976-01-01

413

Oxidation of nitroxyl anion to nitric oxide by copper ions  

PubMed Central

This study made use of a nitric oxide-sensitive electrode to examine possible means of generating nitric oxide from nitroxyl anion (NO?) released upon the decomposition of Angeli's salt. Our results show that copper ions (from CuSO4) catalyze the rapid and efficient oxidation of nitroxyl to nitric oxide. Indeed, the concentrations of copper required to do so (0.1–100??M) are roughly 100-times lower than those required to generate equivalent amounts of nitric oxide from S-nitroso-N-acetyl-D,L-penicillamine (SNAP). Experiments with ascorbate (1?mM), which reduces Cu2+ ions to Cu+, and with the Cu2+ chelators, EDTA and cuprizone, and the Cu+ chelator, neocuproine, each at 1?mM, suggest that the oxidation is catalyzed by copper ions in both valency states. Some compounds containing other transition metals, i.e. methaemoglobin, ferricytochrome c and Mn(III)TMPyP, were much less efficient than CuSO4 in catalyzing the formation of nitric oxide from nitroxyl, while FeSO4, FeCl3, MnCl2, and ZnSO4 were inactive. Of the copper containing enzymes examined, Cu-Zn superoxide dismutase and ceruloplasmin were weak generators of nitric oxide from nitroxyl, even at concentrations (2500 and 30?u?ml?1, respectively) vastly greater than are present endogenously. Two others, ascorbate oxidase (10?u?ml?1) and tyrosinase (250?u?ml?1) were inactive. Our findings suggest that a copper-containing enzyme may be responsible for the rapid oxidation of nitroxyl to nitric oxide by cells, but the identity of such an enzyme remains elusive. PMID:10991931

Nelli, Silvia; Hillen, Mark; Buyukafsar, Kansu; Martin, William

2000-01-01

414

Biochemistry of Dissimilatory Sulfur Oxidation  

Microsoft Academic Search

The long term goals of this research were to define the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during the dissimilatory oxidation of sulfur practiced by various species of the thiobacilli. Specific adhesion of the thiobacilli to elemental sulfur was studied by electrical impedance, dynamic light scattering, laser Doppler velocimetry, and optical trapping

Blake II

2003-01-01

415

Oxidative Imbalance and Anxiety Disorders  

PubMed Central

The oxidative imbalance appears to have an important role in anxiety development. Studies in both humans and animals have shown a strong correlation between anxiety and oxidative stress. In humans, for example, the increased malondialdehyde levels and discrepancies in antioxidant enzymes in erythrocytes have been observed. In animals, several studies also show that anxiety-like behavior is related to the oxidative imbalance. Moreover, anxiety-like behavior can be caused by pharmacological-induced oxidative stress. Studies using knockout or overexpression of antioxidant enzymes have shown a relationship between anxiety-like behavior and oxidative stress. Related factors of oxidative stress that could influence anxious behavior are revised, including impaired function of different mitochondrial proteins, inflammatory cytokines, and neurotrophic factors. It has been suggested that a therapy specifically focus in reducing reactive species production may have a beneficial effect in reducing anxiety. However, the neurobiological pathways underlying the effect of oxidative stress on anxiety symptoms are not fully comprehended. The challenge now is to identify the oxidative stress mechanisms likely to be involved in the induction of anxiety symptoms. Understanding these pathways could help to clarify the neurobiology of the anxiety disorder and provide tools for new discovery in therapies and preventive strategies. PMID:24669212

R, Krolow; D. M, Arcego; C, Noschang; S. N, Weis; C, Dalmaz

2014-01-01

416

Automated analysis of oxidative metabolites  

NASA Technical Reports Server (NTRS)

An automated system for the study of drug metabolism is described. The system monitors the oxidative metabolites of aromatic amines and of compounds which produce formaldehyde on oxidative dealkylation. It includes color developing compositions suitable for detecting hyroxylated aromatic amines and formaldehyde.

Furner, R. L. (inventor)

1974-01-01

417

INSULIN SENSITIZERS AND OXIDATIVE STRESS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The leading causes of oxidative stress include hyperglycemia, hyperinsulinemia and insulin resistance and it may be postulated that oxidative stress represents the common pathway through which hyperglycemia and insulin resistance induce depressed insulin action. Two factors that have been shown to...

418

ENGINEERING BULLETIN: CHEMICAL OXIDATION TREATMENT  

EPA Science Inventory

Oxidation destroys hazardous contaminants by chemically converting them to nonhazardous or less toxic compounds that are ideally more stable, less mobile, and/or inert. However, under some conditions, other hazardous compounds may be formed. The oxidizing agents most commonly use...

419

Introduction Transparent conducting oxides (TCOs)  

E-print Network

Introduction Transparent conducting oxides (TCOs) have been known and employed tech- nologically of transparent conductivity continues to ex- pand and promises a pathway to dramat- ically improved materials and Thin- Film Strategies for New Transparent Conducting Oxides A.J. Freeman, K.R. Poeppelmeier, T.O. Mason

Poeppelmeier, Kenneth R.

420

Metal oxide films on metal  

DOEpatents

A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

Wu, Xin D. (Los Alamos, NM); Tiwari, Prabhat (Los Alamos, NM)

1995-01-01

421

Persistent oxidative stress in cancer  

Microsoft Academic Search

DNA of cancers such as renal cell carcinoma and mammary invasive ductal carcinoma, is persistently exposed to more oxidative stress than that of adjacent nornal tissue. We suggest that the concept of ‘persistent oxidative stress in cancer’ may open up a new research area, explaining part of the characteristic tumor biology of cancer such as activated transcription factors and proto-oncogenes,

Shinya Toyokuni; Keisei Okamoto; Junji Yodoi; Hiroshi Hiai

1995-01-01

422

Oxidative stress in prostate cancer  

Microsoft Academic Search

As prostate cancer and aberrant changes in reactive oxygen species (ROS) become more common with aging, ROS signaling may play an important role in the development and progression of this malignancy. Increased ROS, otherwise known as oxidative stress, is a result of either increased ROS generation or a loss of antioxidant defense mechanisms. Oxidative stress is associated with several pathological

Lakshmipathi Khandrika; Binod Kumar; Sweaty Koul; Paul Maroni; Hari K. Koul

2009-01-01

423

Opportunities for functional oxides in yttrium oxide-titanium oxide-zirconium oxide system: Applications for novel thermal barrier coatings  

Microsoft Academic Search

This dissertation is an investigation of materials and processed under consideration for next generation thermal structural oxides with potential applications as thermal barrier coatings; wherein, high temperature stability and mechanical properties affect durability. Two notable next generation materials systems under investigation are pyrochlore and co-doped zirconia oxides. The motivation for this work is based on current limitations of the currently

Wesley Francillon

2009-01-01

424

Biological water oxidation.  

PubMed

Photosystem II (PSII), a multisubunit pigment-protein supercomplex found in cyanobacteria, algae, and plants, catalyzes a unique reaction in nature: the light-driven oxidation of water. Remarkable recent advances in the structural analysis of PSII now give a detailed picture of the static supercomplex on the molecular level. These data provide a solid foundation for future functional studies, in particular the mechanism of water oxidation and oxygen release. The catalytic core of the PSII is a tetramanganese-calcium cluster (Mn?O?Ca), commonly referred to as the oxygen-evolving complex (OEC). The function of the OEC rests on its ability to cycle through five metastable states (Si, i = 0-4), transiently storing four oxidizing equivalents, and in so doing, facilitates the four electron water splitting reaction. While the latest crystallographic model of PSII gives an atomic picture of the OEC, the exact connectivity within the inorganic core and the S-state(s) that the X-ray model represents remain uncertain. In this Account, we describe our joint experimental and theoretical efforts to eliminate these ambiguities by combining the X-ray data with spectroscopic constraints and introducing computational modeling. We are developing quantum chemical methods to predict electron paramagnetic resonance (EPR) parameters for transition metal clusters, especially focusing on spin-projection approaches combined with density functional theory (DFT) calculations. We aim to resolve the geometric and electronic structures of all S-states, correlating their structural features with spectroscopic observations to elucidate reactivity. The sequence of manganese oxidations and concomitant charge compensation events via proton transfer allow us to rationalize the multielectron S-state cycle. EPR spectroscopy combined with theoretical calculations provides a unique window into the tetramangenese complex, in particular its protonation states and metal ligand sphere evolution, far beyond the scope of static techniques such as X-ray crystallography. This approach has led, for example, to a detailed understanding of the EPR signals in the S?-state of the OEC in terms of two interconvertible, isoenergetic structures. These two structures differ in their valence distribution and spin multiplicity, which has important consequences for substrate binding and may explain its low barrier exchange with solvent water. New experimental techniques and innovative sample preparations are beginning to unravel the complex sequence of substrate uptake/inclusion, which is coupled to proton release. The introduction of specific site perturbations, such as replacing Ca²? with Sr²?, provides discrete information about the ligand environment of the individual Mn ions. In this way, we have identified a potential open coordination site for one Mn center, which may serve as a substrate binding site in the higher S-states, such as S? and S?. In addition, we can now monitor the binding of the substrate water in the lower S-states (S? and S?) using new EPR-detected NMR spectroscopies. These studies provided the first evidence that one of the substrates is subsumed into the complex itself and forms an oxo-bridge between two Mn ions. This result places important new restrictions on the mechanism of O-O bond formation. These new insights from nature's water splitting catalyst provide important criteria for the rational design of bioinspired synthetic catalysts. PMID:23506074

Cox, Nicholas; Pantazis, Dimitrios A; Neese, Frank; Lubitz, Wolfgang

2013-07-16

425

Polymorphism of phosphoric oxide  

USGS Publications Warehouse

The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

Hill, W.L.; Faust, G.T.; Hendricks, S.B.

1943-01-01

426

Ethylene oxide potential toxicity.  

PubMed

The future of ethylene oxide (EO) sterilization has been questioned, owing to its associated toxicity. EO has been around for more than 60 years, mainly due to its recognized characteristics of reliability and effectiveness, coupled with the process flexibility, as well as its compatibility with most mechanical devices. Despite the well-known EO toxicity, the undesirable effects of medical devices' EO residues on the patient's health have not yet been well established. There are limitations related to the current risk-assessment studies. To overcome these drawbacks, demands on greater safety are increasing, which lead to improvements in sterilizers and aeration equipment, as well as the design of the processes. The paper under evaluation highlights risks related to EO sterilization of materials used during processing of stem cells for transplantation, but is an example of a study where the dose of the residues in the devices is not considered. PMID:18452382

da Cunha Mendes, Gisela Cristina; da Silva Brandão, Teresa Ribeiro; Miranda Silva, Cristina Luisa

2008-05-01

427

Ultra Supercritical Steamside Oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, which are goals of the U.S. Department of Energy's Advanced Power Systems Initiatives. Most current coal power plants in the U.S. operate at a maximum steam temperature of 538 C. However, new supercritical plants worldwide are being brought into service with steam temperatures of up to 620 C. Current Advanced Power Systems goals include coal generation at 60% efficiency, which require steam temperatures of up to 760 C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections. Initial results of this research are presented.

Holcomb, Gordon R.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Ziomek-Moroz, Malgorzata

2005-01-01

428

P-31 / Schlott P-31: Nodule Formation on Indium-Oxide Tin-Oxide  

E-print Network

P-31 / Schlott P-31: Nodule Formation on Indium-Oxide Tin-Oxide Sputtering Targets M. Schlott, M from indium-oxide tin-oxide (ITO) targets [1]. Unfor- tunately, black growths, or nodules, commonly isostatic pressing partly reduced powder mixtures of 90 wt.% indium-oxide and 10 wt.% tin-oxide [4

429

Chronic inflammation and oxidative stress  

PubMed Central

Helicobacter pylori is the leading risk factor associated with gastric carcinogenesis. H. pylori leads to chronic inflammation because of the failure of the host to eradicate the infection. Chronic inflammation leads to oxidative stress, deriving from immune cells and from within gastric epithelial cells. This is a main contributor to DNA damage, apoptosis and neoplastic transformation. Both pathogen and host factors directly contribute to oxidative stress, including H. pylori virulence factors, and pathways involving DNA damage and repair, polyamine synthesis and metabolism, and oxidative stress response. Our laboratory has recently uncovered a mechanism by which polyamine oxidation by spermine oxidase causes H2O2 release, DNA damage and apoptosis. Our studies indicate novel targets for therapeutic intervention and risk assessment in H. pylori-induced gastric cancer. More studies addressing the many potential contributors to oxidative stress, chronic inflammation, and gastric carcinogenesis are essential for development of therapeutics and identification of gastric cancer biomarkers. PMID:23811829

Hardbower, Dana M; de Sablet, Thibaut; Chaturvedi, Rupesh; Wilson, Keith T

2013-01-01

430

Electrodissolution of electrodeposited iron oxides  

SciTech Connect

Galvanostatic reduction of ferric oxide was studied in phosphate solutions over a range of pH values. The oxides were prepared on gold by anodic electrodeposition from dilute ferrous borate solution. With increased pH, the potential of the reduction arrests decreased and the charge associated with the arrest increased. A dependence of -60 mV/pH was observed except between pH 7.5 and 8.5 where the slope approximated -180 mV/pH. Above pH 7.5 the slope was consistent with the thermodynamic predicted slope of -180 mV/pH expected from reductive dissolution of ferric oxide forming soluble ferrous ions. At higher pH values, a slope of -60 mV/pH has been accounted for by oxide reduction to form a solid lower valent oxide.

Isaacs, H.S.; Ryan, M.P. [Brookhaven National Lab., Upton, NY (United States); Kalonousky, D.N. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Materials Science; Virtanen, S. [Swiss Federal Inst. of Tech., Zurich (Switzerland). Inst. of Materials Chemistry and Corrosion

1996-12-31

431

BRCA1 and Oxidative Stress  

PubMed Central

The breast cancer susceptibility gene 1 (BRCA1) has been well established as a tumor suppressor and functions primarily by maintaining genome integrity. Genome stability is compromised when cells are exposed to oxidative stress. Increasing evidence suggests that BRCA1 regulates oxidative stress and this may be another mechanism in preventing carcinogenesis in normal cells. Oxidative stress caused by reactive oxygen species (ROS) is implicated in carcinogenesis and is used strategically to treat human cancer. Thus, it is essential to understand the function of BRCA1 in oxidative stress regulation. In this review, we briefly summarize BRCA1’s many binding partners and mechanisms, and discuss data supporting the function of BRCA1 in oxidative stress regulation. Finally, we consider its significance in prevention and/or treatment of BRCA1-related cancers. PMID:24704793

Yi, Yong Weon; Kang, Hyo Jin; Bae, Insoo

2014-01-01

432

Delivering nitric oxide with nanoparticles.  

PubMed

While best known for its important signalling functions in human physiology, nitric oxide is also of considerable therapeutic interest. As such, nanoparticle-based systems which enable the sustained exogenous delivery of nitric oxide have been the subject of considerable investigation in recent years. Herein we review the various nanoparticle systems that have been used to date for nitric oxide delivery, and explore the array of potential therapeutic applications that have been reported. Specifically, we discuss the modification of sol-gel based silica particles, functionalised metal/metal oxide nanoparticles, polymer-coated metal nanoparticles, dendrimers, micelles and star polymers to impart nitric oxide release capability. We also consider the various areas in which therapeutic applications are envisaged: wound healing, antimicrobial applications, cardiovascular treatments, sexual medicine and cancer treatment. Finally, we discuss possible future directions for this versatile and potentially important technology. PMID:25665865

Quinn, John F; Whittaker, Michael R; Davis, Thomas P

2015-05-10

433

21 CFR 73.2991 - Zinc oxide.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Zinc oxide. 73.2991 Section 73.2991...CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and...

2011-04-01

434

21 CFR 73.2991 - Zinc oxide.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Zinc oxide. 73.2991 Section 73.2991...CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and...

2014-04-01

435

21 CFR 73.2991 - Zinc oxide.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Zinc oxide. 73.2991 Section 73.2991...CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and...

2012-04-01

436

21 CFR 73.2991 - Zinc oxide.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Zinc oxide. 73.2991 Section 73.2991...CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and...

2013-04-01

437

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2014-04-01

438

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2013-04-01

439

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2011-04-01

440

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2012-04-01

441

21 CFR 73.3125 - Iron oxides.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

2010-04-01

442

EFFECTS OF PHOTOCHEMICAL OXIDANTS ON PLANTS  

EPA Science Inventory

Photochemical oxidants are found in 'photochemical smog' which is a complex mixture of primary and secondary air pollutants. The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarbons, their precursors. Th...

443

21 CFR 184.1431 - Magnesium oxide.  

Code of Federal Regulations, 2012 CFR

...more rigorous conditions (1200 °C for 12 hours) produces heavy magnesium oxide. Light magnesium oxide is converted to heavy magnesium oxide by sustained heating at high temperatures. (b) The ingredient meets the specifications of...

2012-04-01

444

21 CFR 184.1431 - Magnesium oxide.  

Code of Federal Regulations, 2013 CFR

...more rigorous conditions (1200 °C for 12 hours) produces heavy magnesium oxide. Light magnesium oxide is converted to heavy magnesium oxide by sustained heating at high temperatures. (b) The ingredient meets the specifications of...

2013-04-01

445

21 CFR 184.1431 - Magnesium oxide.  

Code of Federal Regulations, 2011 CFR

...more rigorous conditions (1200 °C for 12 hours) produces heavy magnesium oxide. Light magnesium oxide is converted to heavy magnesium oxide by sustained heating at high temperatures. (b) The ingredient meets the specifications of...

2011-04-01

446

21 CFR 184.1431 - Magnesium oxide.  

Code of Federal Regulations, 2014 CFR

...more rigorous conditions (1200 °C for 12 hours) produces heavy magnesium oxide. Light magnesium oxide is converted to heavy magnesium oxide by sustained heating at high temperatures. (b) The ingredient meets the specifications of...

2014-04-01

447

21 CFR 184.1431 - Magnesium oxide.  

Code of Federal Regulations, 2010 CFR

...more rigorous conditions (1200 °C for 12 hours) produces heavy magnesium oxide. Light magnesium oxide is converted to heavy magnesium oxide by sustained heating at high temperatures. (b) The ingredient meets the specifications of...

2010-04-01

448

Cellular antioxidant and pro-oxidant actions of nitric oxide  

Microsoft Academic Search

We describe a biphasic action of nitric oxide (NO) in its effects on oxidative killing of isolated cells: low concentrations protect against oxidative killing, while higher doses enhance killing, and these two effects occur by distinct mechanisms. While low doses of NO (from (Z)-1-[N-(3-ammonio propyl)-N-(n-propyl)-amino]-diazen-1-ium-1,22 diolate [PAPA\\/NO] or S-nitroso-N-acetyl-L-penicillamine [SNAP] prevent killing of rat hepatocytes byt-butylhydroperoxide (tBH), further increasing doses

Mahesh S Joshi; Julie L Ponthier; Jack R Lancaster

1999-01-01

449

The oxidation of carbon monoxide using tin oxide based catalysts  

NASA Technical Reports Server (NTRS)

The preparation conditions for precious metal/tin oxide catalysts were optimized for maximum carbon monoxide/oxygen recombination efficiency. This was achieved by controlling the tin digestion, the peptization to form the sol, the calcination process and the method of adding the precious metals. Extensive studies of the tin oxide structure were carried out over the temperature range 20 to 500 C in air or hydrogen environments using Raman scattering and X ray diffraction. Adsorbed species on tin oxide, generated in an environment containing carbon monoxide, gave rise to a Raman band at about 1600 cm(exp -1) which was assigned to carbonaceous groups, possible carbonate.

Sampson, Christopher F.; Jorgensen, Norman

1990-01-01

450

Catalysis by Thin Oxide Films and Oxide Nanoparticles  

Microsoft Academic Search

Model systems for transition and noble metal oxide catalysts, either as thin films or nanoparticles, were prepared by vacuum-deposition of oxides or oxidation of metals (particles, thin films, single crystals). These systems, including Ga2O3, In2O3, V2O3, V2O5, Nb2O5, Pd5O4 and PdO, are well suited for atomic scale characterization by surface-specific methods and for catalytic tests. Investigations of structure and composition

Günther Rupprechter; Simon Penner

2010-01-01

451

Uranium Metal to Oxide Conversion by Air Oxidation ?Process Development  

SciTech Connect

Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

Duncan, A

2001-12-31

452

Ethanol oxidation on metal oxide-supported platinum catalysts  

SciTech Connect

Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on the standard three-way catalysts, the conversion of unburned ethanol is low because both ethanol and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.

L. M. Petkovic 090468; Sergey N. Rashkeev; D. M. Ginosar

2009-09-01

453

Manganese oxidation by Leptothrix discophora.  

PubMed Central

Cells of Leptothrix discophora SS1 released Mn2+-oxidizing factors into the medium during growth in batch culture. Manganese was optimally oxidized when the medium was buffered with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) at pH 7.5. Manganese-oxidizing activity in the culture medium in which this strain had been grown previously was sensitive to heat, phosphate, Tris, NaN3, HgCl2 NaCl, sodium dodecyl sulfate, and pronase; 0.5 mol of O2 was consumed per mol of MnO2 formed. During Mn2+ oxidation, protons were liberated. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two protein-containing bands were detected in the spent culture medium. One band had an apparent molecular weight of 110,000 and was predominant in Mn2+-oxidizing activity. The second product (Mr 85,000) was only detected in some cases and probably represents a proteolytic breakdown moiety of the 110,000-Mr protein. The Mn2+-oxidizing factors were associated with the MnO2 aggregates that had been formed in spent culture medium. After solubilization of this MnO2 with ascorbate, Mn2+-oxidizing activity could be recovered. Images PMID:3804969

Boogerd, F C; de Vrind, J P

1987-01-01

454

Oxidized magnetosomes in magnetotactic bacteria  

NASA Astrophysics Data System (ADS)

Single domain magnetite particles formed in chain assemblies by magnetotactic bacteria (MTB) are taken as proxy in inferring environmental and Earth's magnetism. The reliable use of magnetosomes in MTB, or their fossil remains (magnetofossils), requires that they are unaffected by oxidation. Here we present experimental data from saturation isothermal remanent magnetization (SIRM) and ferromagnetic resonance spectroscopy (FMR) between room temperature and 10 K, which were applied to detect oxidation in intact MTB. The distinction of non-oxidized from oxidized MTB-assemblies is based mainly on two different characteristic physical properties: (i) the intrinsic Verwey transition in pure magnetite, and (ii) blocking of spins of nano-sized products formed during oxidation at the surface or the interior of the magnetosomes. Suppression of the Verwey transition due to oxidation prevents the shift of the anisotropy axes, which in turn conserves the anisotropic properties at room temperature down to low temperature. The presented methodology assures a distinction between non- and oxidized magnetite assemblies, with pronounced certainty, unlike standard dc methods.

Gehring, Andreas U.; Charilaou, Michalis; García-Rubio, Inés

2012-04-01

455

Mechanism of Bacterial Pyrite Oxidation  

PubMed Central

The oxidation by Ferrobacillus ferrooxidans of untreated pyrite (FeS2) as well as HCl-pretreated pyrite (from which most of the acid-soluble iron species were removed) was studied manometrically. Oxygen uptake was linear during bacterial oxidation of untreated pyrite, whereas with HCl-pretreated pyrite both a decrease in oxygen uptake at 2 hr and nonlinear oxygen consumption were observed. Ferric sulfate added to HCl-pretreated pyrite restored approximately two-thirds of the decrease in total bacterial oxygen uptake and caused oxygen uptake to revert to nearly linear kinetics. Ferric sulfate also oxidized pyrite in the absence of bacteria and O2; recovery of ferric and ferrous ions was in excellent agreement with the reaction Fe2(SO4)3 + FeS2 = 3FeSO4 + 2S, but the elemental sulfur produced was negligible. Neither H2S nor S2O32? was a product of the reaction. It is probable that two mechanisms of bacterial pyrite oxidation operate concurrently: the direct contact mechanism which requires physical contact between bacteria and pyrite particles for biological pyrite oxidation, and the indirect contact mechanism according to which the bacteria oxidize ferrous ions to the ferric state, thereby regenerating the ferric ions required for chemical oxidation of pyrite. PMID:6051342

Silverman, Melvin P.

1967-01-01

456

IRON OXIDE NANOPARTICLE-INDUCED OXIDATIVE STRESS AND INFLAMMATION  

EPA Science Inventory

Nanoparticle Physicochemical Characterizations We first focused on creating NP systems that could be used to test our hypotheses and assessing their stability in aqueous media. The iron oxide NP systems were not stable in cell culture medium o...

457

Alumina composites for oxide/oxide fibrous monoliths  

SciTech Connect

Most work on ceramic fibrous monoliths (FMs) has focused on the Si{sub 3}N{sub 4}/BN system. In an effort to develop oxidation-resistant FMs, several oxide systems have recently been examined. Zirconia-toughened alumina and alumina/mullite appear to be good candidates for the cell phase of FMs. These composites offer higher strength and toughness than pure alumina and good high-temperature stability. By combining these oxides, possibly with a weaker high-temperature oxide as the cell-boundary phase, it should be possible to product a strong, resilient FM that exhibits graceful failure. Several material combinations have been examined. Results on FM fabrication and microstructural development are presented.

Cruse, T. A.; Polzin, B. J.; Picciolo, J. J.; Singh, D.; Tsaliagos, R. N.; Goretta, K. C.

2000-03-01

458

Treatment of exhaust gas containing sulfur oxides and nitrogen oxides  

SciTech Connect

A method of treating an exhaust gas at a high temperature containing nitrogen oxides and sulfur oxides is described. The method consists of bringing the exhaust gas into contact with an absorbing solution containing at least an iron chelate salt and potassium sulfite to thereby convert said nitrogen oxides and sulfur oxides into a mixture of potassium imidodisulfonate, potassium dithionate and potassium sulfate, characterized in that (1) the exhaust gas at a high temperature is cooled to a temperature below 80/sup 0/C before bringing it into contact with the absorbing solution, (2) the concentration of potassium sulfite as the sulfite component in the absorbing solution is kept at least at 0.8 mol/kg, and (3) the mixture of salts produced in the absorbing solution is crystallized by cooling and separated by filtering the absorbing solution.

Kudo, Y.; Nomoto, K.

1981-03-10

459

Detailed mechanism of benzene oxidation  

NASA Technical Reports Server (NTRS)

A detailed quantitative mechanism for the oxidation of benzene in both argon and nitrogen diluted systems is presented. Computed ignition delay time for argon diluted mixtures are in satisfactory agreement with experimental results for a wide range of initial conditions. An experimental temperature versus time profile for a nitrogen diluted oxidation was accurately matched and several concentration profiles were matched qualitatively. Application of sensitivity analysis has given approximate rate constant expressions for the two dominant heat release reactions, the oxidation of C6H5 and C5H5 radicals by molecular oxygen.

Bittker, David A.

1987-01-01

460

Organocatalyzed anodic oxidation of aldehydes.  

PubMed

A method for the catalytic formation of electroauxiliaries and subsequent anodic oxidation has been developed. The process interfaces N-heterocyclic carbene-based organocatalysis with electro-organic synthesis to achieve direct oxidation of catalytically generated electroactive intermediates. We demonstrate the applicability of this method as a one-pot conversion of aldehydes to esters for a broad range of aldehyde and alcohol substrates. Furthermore, the anodic oxidation reactions are very clean, producing only H(2) gas as a result of cathodic reduction. PMID:22768916

Finney, Eric E; Ogawa, Kelli A; Boydston, Andrew J

2012-08-01

461

Titanium oxide\\/aluminum oxide multilayer reflectors for  

Microsoft Academic Search

Twenty bilayers of titanium oxide and aluminum oxide with the layer-pair thickness of 4.43 nm on a silicon substrate were fabricated for novel multilayer reflectors at water-window wavelengths by an atomic layer deposition method of controlled growth with sequential surface chemical reactions. The high reflectance of over 30% at a wavelength of 2.734 nm and an incident angle of 71.8°

Hiroshi Kumagai; Koichi Toyoda; Katsutaro Kobayashi; Minoru Obara; Yasuhiro Iimura

1997-01-01

462

Tryptophan oxidation in proteins exposed to thiocyanate-derived oxidants.  

PubMed

Human defensive peroxidases, including lactoperoxidase (LPO) and myeloperoxidase (MPO), are capable of catalyzing the oxidation of halides (X(-)) by H2O2 to give hypohalous acids (HOX) for the purpose of cellular defense. Substrate selectivity depends upon the relative abundance of the halides, but the pseudo-halide thiocyanate (SCN(-)) is a major substrate, and sometimes the exclusive substrate, of all defensive peroxidases in most physiologic fluids. The resulting hypothiocyanous acid (HOSCN) has been implicated in cellular damage via thiol oxidation. While thiols are believed to be the primary target of HOSCN in vivo, Trp residues have also been implicated as targets for HOSCN. However, the mechanism involved in HOSCN-mediated Trp oxidation was not established. Trp residues in proteins appeared to be susceptible to oxidation by HOSCN, whereas free Trp and Trp residues in small peptides were found to be unreactive. We show that HOSCN-induced Trp oxidation is dependent on pH, with oxidation of free Trp, and Trp-containing peptides observed when the pH is below 2. These conditions mimic those employed previously to precipitate proteins after treatment with HOSCN, which accounts for the discrepancy in the results reported for proteins versus free Trp and small peptides. The reactant in these cases may be thiocyanogen ((SCN)2), which is produced by comproportionation of HOSCN and SCN(-) at low pH. Reaction of thiocyanate-derived oxidants with protein Trp residues at low pH results in the formation of a number of oxidation products, including mono- and di-oxygenated derivatives, which are also formed with other hypohalous acids. Our data suggest that significant modification of Trp by HOSCN in vivo is likely to have limited biological relevance. PMID:25172223

Bonifay, Vincent; Barrett, Tessa J; Pattison, David I; Davies, Michael J; Hawkins, Clare L; Ashby, Michael T

2014-12-15

463

Hafnium oxide and hafnium aluminum oxide for CMOS applications  

Microsoft Academic Search

The continued scaling of the CMOS gate dielectric to its fundamental limit governed by the large gate leakage current requires the introduction of high-k material for sub-100-nm technology nodes. This dissertation research deals with the physical and electrical properties of a promising high-k candidate, hafnium oxide, as a gate dielectric for CMOS applications. Hafnium oxide made by the Jet-Vapor-Deposition process

Wenjuan Zhu

2003-01-01

464

Cobalt porphyrin-catalyzed alkane oxidations using dioxygen as oxidant  

Microsoft Academic Search

In a mixture of trifluoroacetic acid and water, cobalt(II) porphyrin complexes catalyze the oxidation of alkanes by dioxygen. Carbon monoxide is required as a coreductant for the oxidations to proceed. While the turnover rates are slow, the system displays unusual selectivity in that primary C?H bonds are more reactive than the weaker secondary C?H bonds or C?H bonds ? to

Hui Tang; Chengyu Shen; Minren Lin; Ayusman Sen

2000-01-01

465

Oxidants from Pulverized Minerals  

NASA Astrophysics Data System (ADS)

Joel Hurowitz (previously at State University of New York at Stony Brook and now at the Jet Propulsion Laboratory), Nick Tosca, Scott McLennan, and Martin Schoonen (SUNY at Stony Brook) studied the production of hydrogen peroxide from freshly pulverized minerals in solution. Their experiments focused on olivine, augite, and labradorite; silicate minerals of basaltic planetary surfaces, such as the Moon and Mars, that are exposed to the intense crushing and grinding of impact cratering processes. The hydrogen peroxide produced in the experiments was enough to adequately explain the oxidizing nature of Martian regolith first determined by the Viking Landers and the results suggest, for the first time, that mechanically activated mineral surfaces may be an important part of the overall explanation for the Viking Lander biology experiment results. Hurowitz and coauthors further showed that when the pulverized minerals are heat-treated to high temperature under vacuum (to cause dehydroxylation) there is almost a 20 times increase in hydrogen peroxide production, a result which may be highly relevant to lunar dust. These careful studies demonstrate the importance of and concern about reactive dusts on planetary surfaces from two standpoints: the health of astronauts on surface maneuvers who may inadvertently breath it and the viability of possible Martian organic species to survive in such a corrosive, antiseptic surface environment.

Martel, L. M. V.

2007-06-01