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1

Effects of heat-activated persulfate oxidation on soil microorganisms.  

PubMed

The effects of heat-activated persulfate on indigenous microorganisms and microcosms augmented with Pseudomonas putida KT2440 were studied in laboratory batch reactors with aquifer material. Microscopic enumeration was used to measure the changes in cell density, and acetate consumption was used to evaluate metabolic activity after exposure to activated persulfate. The cell enumerations showed that persulfate concentrations up to 10 g/L did not affect the indigenous microorganisms but were detrimental to P. putida survival. Acetate consumption was inhibited at the highest persulfate dose (10 g/L). The results emphasize the necessity of using multiple toxicity assays and indigenous cultures in order to realistically assess the potential effects of in situ chemical oxidation on soil microorganisms. A comparison to other studies suggests that the effects of activated persulfate on soil microorganisms are less damaging than those of Fenton's reagent and hydrogen peroxide. PMID:17942135

Tsitonaki, Aikaterini; Smets, Barth F; Bjerg, Poul L

2008-02-01

2

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

3

Persulfate Oxidation of Gasoline Compounds  

NASA Astrophysics Data System (ADS)

In situ chemical oxidation (ISCO) using persulfate is a promising remediation technology that can be potentially applied to a wide range of organic contaminants. Gasoline compounds are of particular interest because they extensively impact the soil and groundwater, and are highly persistent and toxic. In this investigation, destruction of specific gasoline compounds (benzene, toluene, ethylbenzenes, xylenes, trimethylbenzenes (TMBs) and naphthalene), and fractions (F1 and F2) by activated and inactivated persulfate was studied at the bench-scale. Aqueous phase batch reactors (25 mL) for inactivated systems employed persulfate at two concentrations (1 or 20 g/L), and activated systems were conducted with a persulfate concentration of 20 g/L. In the activated systems, the ability of hydrogen peroxide or chelated-ferrous as an activator was examined at two experimental conditions (peroxide molar ratio 0.1 and 1.0 with respect to persulfate; and citric acid chelated ferrous at 150 and 600 mg/L). All treatments and controls contained an initial gasoline concentration of approximately 25 mg/L and were run in triplicate. Sampling for gasoline compounds was conducted over <28 day reaction period. The controls showed insignificant degradation for all the gasoline compounds and fractions examined while inactivated persulfate at 1 g/L showed little (<10%) decrease in the concentration of gasoline compounds over the 28 day reaction period. Inactivated persulfate at 20 g/L demonstrated a significant decrease in the aqueous concentration of BTEX (>99%), TMB (>94%) and naphthalene (>71%). Oxidation of the F1 fraction (>94%) was more pronounced than the F2 fraction (>80%), and >93% TPH was oxidized. Use of peroxide as an activator at a molar ratio of 0.1 improved the destruction of TMBs (>99%) and naphthalene (>85%) while maintaining the high removal of BTEX (>99%) compounds. Increase in activator strength (molar ratio 1.0) decreased the destruction of xylenes (>86%) and TMBs (>81%). The decrease in concentration of all the compounds was higher for a molar ratio of 1.0 (<27%) as compared with a molar ratio of 0.1 (<11%). The activation by ferrous concentration resulted in higher oxidation of compounds (except naphthalene) as compared with unactivated or peroxide activated persulfate. 1,3,5-TMB was completed oxidized after 4 days using higher chelated ferrous concentration and after 12 days using lower chelated ferrous concentration for persulfate activation. In general, increase in chelated ferrous concentration resulted in higher oxidation of the gasoline compounds. While oxidation of F1 fraction was similar for two ferrous activation conditions, the oxidation of F2 fraction was lower when ferrous activation at 600 mg/L was employed. Use of persulfate at high dosages by itself or in combination with higher doses of chelated ferrous or optimum doses of peroxide as an activator seems to be a viable option for remediation of gasoline compounds examined in this study. Persulfate appears to be particularly effective in the oxidation of BTEX compounds, but may require ferrous activation for a complete oxidation of TMBs and peroxide activation for oxidation of naphthalene.

Sra, K.; Thomson, N.; Barker, J.

2009-05-01

4

PCE oxidation by sodium persulfate in the presence of solids.  

PubMed

Batch reactor experiments were performed to determine the effects of solids on the oxidation of tetracholoroethylene (PCE) by sodium persulfate in aqueous solution. Based on the rates of PCE degradation and chloride formation, PCE oxidation by heat-activated sodium persulfate at 50 °C in the presence of solids ranged from no detectable oxidation of PCE to the levels observed in water-only reactors. Repeated doses of sodium persulfate, undertaken to overcome the inherent solids oxidant demand, improved the rate and extent of PCE oxidation in reactors containing reference solids; however, no improvement was observed in reactors containing field soils. Additionally, no improvements in PCE oxidation were observed after pretreating Great Lakes and Appling soils with ca. 15 g/kg of sodium persulfate or 30% hydrogen peroxide to remove oxidizable fractions, or acetic acid to remove the carbonate fraction. Based on these results, in situ treatment of Great Lakes and Appling soils with heat-activated sodium persulfate is not anticipated to result in substantial PCE oxidation, while in situ treatment of Fort Lewis soils is anticipated to result in PCE oxidation. This work demonstrates the need to perform soil-specific contaminant treatability tests rather than soil oxidant demand tests when determining oxidant dosage requirements. PMID:21070044

Costanza, Jed; Otaño, Gretell; Callaghan, John; Pennell, Kurt D

2010-12-15

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

Intensification of sonochemical degradation of ammonium perfluorooctanoate by persulfate oxidant.  

PubMed

Ammonium perfluorooctanoate (APFO) is an emerging environmental pollutant attracting significant attention due to its global distribution, high persistence, and bioaccumulation properties. The decomposition of APFO in aqueous solution with a combination of persulfate oxidant and ultrasonic irradiation was investigated. The effects of operating parameters, such as ultrasonic power, persulfate concentration, APFO concentration, and initial media pH on APFO degradation were discussed. In the absence of persulfate, 35.5% of initial APFO in 46.4 ?mol/L solution under ultrasound irradiation, was decomposed rapidly after 120 min with the defluorination ratio reaching 6.73%. In contrast, when 10 mmol/L persulfate was used, 51.2% of initial APFO (46.4 ?mol/L) was decomposed and the defluorination ratio reached 11.15% within 120 min reaction time. Enhancement of the decomposition of APFO can be explained by acceleration of substrate decarboxylation, induced by sulfate radical anions formed from the persulfate during ultrasonic irradiation. The SO4(-•)/APFO reactions at the bubble-water interface appear to be the primary pathway for the sonochemical degradation of the perfluorinated surfactants. PMID:24139324

Hao, Feifei; Guo, Weilin; Wang, Anqi; Leng, Yanqiu; Li, Helian

2014-03-01

13

Oxidation of polyvinyl alcohol by persulfate activated with heat, Fe 2+, and zero-valent iron  

Microsoft Academic Search

The oxidation of polyvinyl alcohol (PVA) by persulfate (S2O82?) activated with heat, Fe2+, and zero-valent iron (Fe(0)) was investigated via batch experiments. It was hypothesized that elevated temperature and the addition of Fe2+ or Fe(0) into a persulfate-water system could enhance the oxidation of PVA by activated persulfate. Increasing the temperature from 20 to 60°C or 80°C accelerated the oxidation

Seok-Young Oh; Hyeong-Woo Kim; Jun-Mo Park; Hung-Suck Park; Chohee Yoon

2009-01-01

14

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

15

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

National Technical Information Service (NTIS)

A fundamental study was conducted to investigate the activation and persistence of persulfate in the subsurface with the overlying objective of evaluating the potential for contact between the oxidant source and contaminants. Mechanistic investigation of ...

R. J. Watts

2011-01-01

16

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

17

Defluorination of aqueous perfluorooctanesulfonate by activated persulfate oxidation.  

PubMed

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 S2O8 (2-) 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 > Fe(2+)/K2S2O8 > US (ultrasound)/K2S2O8. Low pH was favorable for the PFOS defluorination with sulfate radicals. Increase in the amount of S2O8 (2-) had positive effect on PFOS defluorination. However, further increase in amounts of S2O8 (2-) caused insignificant improvement in PFOS defluorination due to elimination of sulfate radicals under high concentration of S2O8 (2-). 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

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.

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

2013-01-01

19

Recovery of Phenanthrene-Degrading Bacteria After Simulated In Situ Persulfate Oxidation in Contaminated Soil  

PubMed Central

A continuous-flow column study was conducted to investigate the long-term effects of persulfate oxidation on the abundance and activity of the indigenous microbial community and phenanthrene-degrading bacteria in contaminated soil from a former manufactured gas plant (MGP) site. Approximately six pore volumes of a 20 g/L persulfate solution were introduced into the column, followed by simulated groundwater for 500 d. Soil samples were collected from the surface of the soil bed and along the column length immediately before and after persulfate injection and up to 500 d following injection. Exposure to persulfate led to a two- to three-log reduction in total bacterial 16S rRNA genes, severe inhibition of 14C-acetate mineralization (as a measure of general microbial activity), and a decrease in community diversity. However, relatively rapid recovery of both bacterial gene abundance and activity was observed within 30 d after persulfate exposure. Mineralization of 14C-phenanthrene was also inhibited but did not recover until 100 d post-oxidation. Known phenanthrene-degrading bacterial groups decreased to below detection limits throughout the column, with recovery times from 100 d to 500 d after persulfate injection. These findings suggest that coupling biological processes with persulfate oxidation is possible, although recovery of specific contaminant degraders may occur much later than the general microbial community recovers. Furthermore, the use of total bacterial quantity or non-specific measures of activity as a surrogate for the recovery of contaminant degraders may be inappropriate for evaluating the compatibility of chemical treatment with subsequent bioremediation.

Richardson, Stephen D.; Lebron, Benjamin L.; Miller, Cass T.; Aitken, Michael D.

2010-01-01

20

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

21

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

22

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 ...

23

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

24

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

25

Bisphenol A treatment by the hot persulfate process: oxidation products and acute toxicity.  

PubMed

In this study, a thermally activated persulfate oxidation process was investigated to treat aqueous Bisphenol A (BPA) solution. The effect of temperature (40-50-60-70°C), initial pH (pH=3.0, 6.5, 9.0 and 11.0) and persulfate concentration (0-20mM) on bisphenol A (BPA) and TOC removals was examined. The activation energy for hot persulfate oxidation of BPA was calculated as 184 ± 12 kJ/mol. Acidic and neutral pH values were more favorable for BPA oxidation than basic pH values. TOC removals did not exhibit a specific pattern with varying initial pHs. Gas chromatography/mass spectrometry was employed to identify oxidation products. Several aromatic and a few aliphatic compounds could be detected including benzaldehyde, p-isopropenyl phenol, 2,3-dimethyl benzoic acid, 3-hydroxy-4-methyl-benzoic acid, ethylene glycol monoformate and succinic acid. Acute toxicity tests conducted with Vibrio fischeri indicated that the inhibitory effect of 88 ?M BPA solution originally being 58%, increased to 84% after 30 min and decreased to 22% after 90 min hot persulfate treatment that could be attributed to the formation and subsequent disappearance of oxidation products. PMID:23433897

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

2013-12-15

26

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,...

27

Carbon isotope fractionation of chlorinated ethenes during oxidation by Fe2+ activated persulfate.  

PubMed

The increased use of persulfate (S(2)O(8)(2-)) for in situ chemical oxidation to treat groundwater and soils contaminated by chlorinated hydrocarbon compounds (CHCs) requires unbiased methods to assess treatment performance. Stable carbon isotope analysis offers a potential tool for assessing the in situ treatment performance of persulfate at sites contaminated with CHCs. This study investigated the extent of C isotope fractionation during oxidation of tetrachloroethene (PCE), trichloroethene (TCE) and cis-dichloroethene (cis-DCE) by persulfate activated by ferrous ion (Fe(2+)). An average carbon isotope enrichment factor ?(bulk) of -4.9‰ for PCE, -3.6‰ for TCE and -7.6‰ for cis-DCE were obtained in batch experiments. Variations in the initial S(2)O(8)(2-)/Fe(2+)/CHC molar ratios did not result in any significant differences in carbon isotope fractionation. The occurrence of carbon isotope fractionation during oxidation and the lack of dependence of enrichment factors upon the S(2)O(8)(2-)/Fe(2+)/CHC molar ratio demonstrate that carbon isotope analysis can potentially be used at contaminated sites as an additional technique to estimate treatment efficacy during oxidation of CHCs by Fe(2+) activated persulfate. PMID:22814410

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

2012-09-01

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

Sodium Persulfate Oxidation for the Remediation of Chlorinated Solvents (USEPA Superfund Innovative Technology Evaluation Program)  

Microsoft Academic Search

This study has been conducted at the University of Connecticut (UCONN) in connection with the USEPA Superfund Innovative Technology\\u000a Evaluation (SITE) program to evaluate a chemical oxidation technology (sodium persulfate) developed at UCONN. A protocol to\\u000a assess the efficacy of oxidation technologies has been used. This protocol, which consists of obtaining data from a treatability\\u000a study, tested two in-situ chemical

M. Amine Dahmani; Kunchang Huang; George E. Hoag

2006-01-01

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

Enhanced dewaterability of sewage sludge in the presence of Fe(II)-activated persulfate oxidation.  

PubMed

The potential benefits of Fe(II)-activated persulfate oxidation on sludge dewatering and its mechanisms were investigated in this study. Capillary suction time (CST) was used to evaluate sludge dewaterability. Both extracellular polymeric substances (EPS) and viscosity were determined in an attempt to explain the observed changes in sludge dewaterability. The optimal conditions to give preferable dewaterability characteristics were found to be persulfate (S(2)O(8)(2-)) 1.2 mmol/gVSS, Fe(II) 1.5 mmol/gVSS, and pH 3.0-8.5, which demonstrated a very high CST reduction efficiency (88.8% reduction within 1 min). It was further observed that both soluble EPS and viscosity played relatively negative roles in sludge dewatering, whereas no correlation was established between sludge dewaterability and bound EPS. Three-dimensional excitation-emission matrix (EEM) fluorescence spectra also revealed that soluble EPS of sludge were degraded and sludge flocs were ruptured by persulfate oxidation, which caused the release of water in the intracellular pace and subsequent improvement of its dewaterability. PMID:22542138

Zhen, Guangyin; Lu, Xueqin; Zhao, Youcai; Chai, Xiaoli; Niu, Dongjie

2012-07-01

35

A novel advanced oxidation process to degrade organic pollutants in wastewater: microwave-activated persulfate oxidation.  

PubMed

This article, for the first time, provides a novel advanced oxidation process based on sulfate radical (SO4*-) to degrade organic pollutants in wastewater: microwave (MW)-activated persulfate oxidation (APO) with or without active carbon (AC). Azo dye acid Orange 7 (AO7) is used as a model compound to investigate the high reactivity of MW-APO. It is found that AO7 (up to 1000 mg/L) is completely decolorized within 5-7 min under an 800 W MW furnace assisted-APO. In the presence of chloride ion (up to 0.50 mol/L), the decolorization is still 100% completed, though delayed for about 1-2 min. Experiments are made to examine the enhancement by AC. It is exciting to find that the 100% decolorization of AO7 (500 mg/L) is achieved within 3 min by MW-APO using 1.0 g/L AC as catalyst, while the degradation efficiency maintains at 50% by MW energy without persulfate after about 5 min. Besides the destruction of visible light chromophore band of AO7 (484 nm), during MW-APO, two bands in the ultraviolet region (228 nm and 310 nm) are rapidly broken down. The removal of COD is about 83%-95% for 500 mg/L AO7. SO4*- is identified with quenching studies using specific alcohols. Both SO4*- and *OH could degrade AO7, but SO4*- plays the dominant role. In a word, MW-APO AC is a new catalytic combustion technology for destruction of organic contamination even for high concentration. PMID:19999962

Yang, Shiying; Wang, Ping; Yang, Xin; Wei, Guang; Zhang, Wenyi; Shan, Liang

2009-01-01

36

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.

37

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

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

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...

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

Comparative study on oxidative treatments of NAPL containing chlorinated ethanes and ethenes using hydrogen peroxide and persulfate in soils.  

PubMed

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 H(2)O(2)-persulfate (HP) co-amendment systems. Citrate, a buffer and iron ligand, was amended to the treatment system to enhance oxidative treatment. Four activation/catalysis methods were employed: (1) oxidant only, (2) oxidant-citrate, (3) oxidant-iron(II), and (4) oxidant-citrate-iron(II). The NAPL treatment effectiveness was the greatest in the CHP reactions, the second in HP, and the third in AP. The effective activation and catalysis methods depended on the oxidant types; oxidant only for CHP and HP and oxidant-citrate-iron for AP. The treatability trend of chlorinated ethanes and ethenes in the soil mixture was as follows: trichloroethene > tetrachloroethene > dichloroethane > trichloroethane > tetrachloroethane. A significant fraction of persulfate remained in the oxidation systems after the 2-day reaction period, especially in the citrate-iron(II) AP. In general, oxidation systems that included citrate maintained a post-treatment pH in the range of 7-9. A final pH of AP oxidation systems was acidic (pH 2-3), where a molar ratio of citrate-iron(II) was less than 1.8 and where no citrate was amended. PMID:22658989

Ko, Saebom; Crimi, Michelle; Marvin, Bruce K; Holmes, Victor; Huling, Scott G

2012-10-15

42

Polyaniline/cellulose fiber composite prepared using persulfate as oxidant for Cr(VI)-detoxification.  

PubMed

Cellulose fibers were engineered by in situ oxidative polymerization of aniline using ammonium persulfate as oxidant/initiator. The polyaniline/cellulose fiber composite was used for the treatment of Cr(VI)-contaminated water, and its effect was evaluated. Under the conditions studied, the composite exhibited very high water detoxification efficiency, as a result of reduction of Cr(VI) to Cr(III) in combination with adsorption of the Cr(III) onto the cellulosic substrate. Cellulose fibers used in the study served two purposes simultaneously, i.e., carrier of polyaniline and the adsorbent for Cr(III). The complexation of polyaniline with cellulose fibers provided synergistic effects on Cr(VI)-detoxification. PMID:23218350

Liu, Xiangyao; Zhou, Wanpeng; Qian, Xueren; Shen, Jing; An, Xianhui

2013-01-30

43

Mechanism of the quenching of the tris(bipyridine)ruthenium(II) emission by persulfate: implications for photoinduced oxidation reactions.  

PubMed

A revised mechanism for the oxidation of the excited state of Ru(bpy)3(2+) with the persulfate anion is described in this work. The formation of the precursor complex in the electron transfer reaction involves ion pairing between the metal complex in ground and excited states and S2O8(2-). The equilibrium constant for the ion-pair formation (K(IP) = 2.7 M(-1)) was determined from electrochemical measurements and analysis of thermal reaction between Ru(bpy)3(2+) and persulfate. It was found to be consistent with the calculated value estimated from the Debye-Hückel model. The analysis of rate constants for reactions between persulfate and various metal complexes indicates that thermal and photochemical reactions most likely proceed through a common pathway. Extremely high reorganization energy (ca. 3.54 eV) for the electron transfer obtained from fitting experimental data with the Marcus equation is indicative of significant nuclear reorganization during the electron transfer step. In view of these results the electron transfer can be described as dissociative probably involving substantial elongation or complete scission of the O-O bond. The proposed model accurately describes experimental results for the quenching of *Ru(bpy)3(2+) over a wide range of persulfate concentrations and resolves some discrepancies between the values of K(IP) and k(et) previously reported. The implications of various factors such as the ionic strength and dielectric constant of the medium are discussed in relation to measurements of the quantum yields in photodriven oxidation reactions employing the Ru(bpy)3(2+)/persulfate couple. PMID:24040757

Lewandowska-Andralojc, A; Polyansky, D E

2013-10-10

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

Microwave-hydrothermal decomposition of perfluorooctanoic acid in water by iron-activated persulfate oxidation  

Microsoft Academic Search

The microwave-hydrothermal decomposition of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in aqueous solution using persulfate activated by zero-valent iron (ZVI) at 60 and 90°C was examined. The results of laboratory study reveal that when PFOA is treated with 5mM persulfate (PS) and ZVI at 90°C for 2h, 67.6% of PFOA is effectively decomposed to form shorter-chain perfluorinated carboxylic acids (PFCAs)

Yu-Chi Lee; Shang-Lien Lo; Pei-Te Chiueh; Yau-Hsuan Liou; Man-Li Chen

2010-01-01

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

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

51

Enhanced degradation of ortho-nitrochlorobenzene by the combined system of zero-valent iron reduction and persulfate oxidation in soils.  

PubMed

ortho-Nitrochlorobenzene (o-NCB) in soil poses significant health risks to human because of its persistence and high toxicity. The removal of o-NCB by both zero-valent iron (ZVI) and chemical oxidation (persulfate) was investigated by batch experiments. The o-NCB removal rate increases significantly from 15.1 to 97.3 % with an increase of iron dosage from 0.1 to 1.0 mmol g(-1). The o-NCB removal rate increases with the decrease of the initial solution pH, and a removal efficiency of 90.3 % is obtained at an initial pH value of 6.8 in this combined system. It is found that temperature and soil moisture could also increase the o-NCB removal rate. The o-NCB degradation rate increases from 83.9 to 96.2 % and from 41.5 to 82.4 % with an increase of temperature (15 to 35 °C) and soil moisture (0.25 to 1.50 mL g(-1)), respectively. Compared to the persulfate oxidation system and ZVI system, the persulfate-iron system shows high o-NCB removal capacity. o-NCB removal rates of 41.5 and 62.4 % are obtained in both the persulfate oxidation system and the ZVI system, while the removal rate of o-NCB is 90.3 % in the persulfate-iron system. PMID:24385185

Xu, Hai-bo; Zhao, Dao-yuan; Li, Yu-jiao; Liu, Pei-ya; Dong, Chang-xun

2014-04-01

52

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

53

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

54

Oxidation of Orange G by persulfate activated by Fe(II), Fe(III) and zero valent iron (ZVI).  

PubMed

Persulfate (PS) was employed in the oxidation of Orange G (OG), an azo dye commonly found in textile wastewaters. Activation of PS was conducted with iron to generate sulfate free radicals (SO4(-)) with high redox potential capable to oxidize most of the organics in water. Identification of oxidation intermediates was carried out by analyzing at different times organic by-products generated from treatment of a concentrate dye solution (11.6 mM) with 153 mM of PS and 20 mM of Fe(II) at 20 °C. Intermediate reaction products (mainly phenol (PH) and benzoquinone (BQ), and in less extent aniline, phenolic compounds and naphthalene type compounds with quinone groups) were identified by GC/MS and HPLC, and an oxidation pathway was proposed for the oxidation of OG with iron activated PS. The effect of iron valence (0, II and III) in the oxidation of an aqueous solution of OG (containing 0.1 mM) was studied in a 0.5 L batch reactor at 20 °C. Initial activator and PS concentrations employed were both 1 mM. Complete pollutant removal was achieved within the first 30 min when iron II or III were employed as activators. Quinone intermediates generated during pollutant oxidation may act as electron shuttles, allowing the reduction of Fe(III) into Fe(II) in the redox cycling of iron. Therefore, activation of PS by Fe(III) allowed complete OG removal. When zero valent iron (ZVI) was employed (particle diameter size 0.74 mm) the limiting step in SO4(-) generation was the surface reaction between ZVI and the oxidant yielding a lower oxidation rate of the dye. An increase in the oxidant dosage (0.2 mM OG, 2 mM Fe(III) and 6 mM PS) allowed complete pollutant and ecotoxicity removal, as well as mineralization close to 75%. PMID:24439838

Rodriguez, S; Vasquez, L; Costa, D; Romero, A; Santos, A

2014-04-01

55

Synergetic pretreatment of waste activated sludge by Fe(II)-activated persulfate oxidation under mild temperature for enhanced dewaterability.  

PubMed

The potential benefits of Fe(II)-activated persulfate (S(2)O(8)(2-)) oxidation under mild temperature in enhancing the dewaterability of waste activated sludge were investigated. Capillary suction time (CST) was used to characterize sludge dewatering. Zeta potential, particle size distribution, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy, fourier-transformed infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM) were employed to explore influencing mechanisms. The results indicated that the dewaterability was deteriorated with single thermal treatment, but significantly enhanced in the presence of Fe(II)-S(2)O(8)(2-) oxidation and further advanced together with thermal treatment. EEM and FT-IR analysis indicated that combined thermal and Fe(II)-S(2)O(8)(2-) oxidation pretreatment led to degrading of tyrosine and tryptophan protein-like substances in extracellular polymeric substances (EPS) and cleavage of linkages in polymeric backbone. SEM images further revealed the rupture of sludge flocs at the colloidal scale, which contributed to the release of EPS-bound water and interstitial water trapped between flocs, and subsequent enhanced dewaterability. PMID:22989633

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

2012-11-01

56

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

57

Innovative combination of electrolysis and Fe(II)-activated persulfate oxidation for improving the dewaterability of waste activated sludge.  

PubMed

The feasibility of electrolysis integrated with Fe(II)-activated persulfate (S2O8(2-)) oxidation to improve waste activated sludge (WAS) dewaterability was evaluated. The physicochemical properties (sludge volume (SV), total suspended solids (TSS) and volatile suspended solids (VSS)) and extracellular polymeric substances (EPS), including slime EPS, loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) were characterized to identify their exact roles in sludge dewatering. While dewaterability negatively corresponded to LB-EPS, TB-EPS, protein (PN) and polysaccharide (PS) in LB-EPS and TB-EPS, it was independent of SV, TSS, VSS, slime EPS and PN/PS. Further study through scanning electron microscope (SEM) verified the entrapment of bacterial cells by TB-EPS, protecting them against electrolysis disruption. Comparatively, electrolysis integrated with S2O8(2-)/Fe(II) oxidation was able to effectively disrupt the protective barrier and crack the entrapped cells, releasing the water inside EPS and cells. Therefore, the destruction of both TB-EPS and cells is the fundamental reason for the enhanced dewaterability. PMID:23570713

Zhen, Guang-Yin; Lu, Xue-Qin; Li, Yu-You; Zhao, You-Cai

2013-05-01

58

In situ iron activated persulfate oxidative fluid sparging treatment of TCE contamination — A proof of concept study  

NASA Astrophysics Data System (ADS)

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 2O 82-) can be activated by ferrous ion (Fe 2+) to generate sulfate radicals ( Eo = 2.6 V), which are capable of destroying trichloroethylene (TCE). The property of polarity inhibits S 2O 82- or sulfate radical (SO 4rad - ) 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 2O 82- 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 2O 82- fluid sparging curtain. Also, the effect of a solubility enhancing chemical, hydroxypropyl-?-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.

Liang, Chenju; Lee, I.-Ling

2008-09-01

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

Mineralization and deflourization of 2,2,3,3-tetrafluoro-1-propanol (TFP) by UV/persulfate oxidation and sequential adsorption.  

PubMed

This work demonstrates the combination of UV/persulfate and adsorption processes for treating 2,2,3,3-tetrafluoro-1-propanol (TFP) wastewater. Under the optimum conditions, 20mM persulfate (S(2)O(8)(2-)), 254 nm UV-C, and pH 3, 99.7% of TOC removal from an initial TFP solution of 1.39 mM was achieved. The photolysis of persulfate (S(2)O(8)(2-)) by UV irradiation yielded the sulfate radical (SO(4)(-)) with high activity, which mineralized most of the TFP in 2h. The released fluoride ions were then removed by using a waste iron oxide, BT-4 adsorbent. 20 g L(-1) BT-4 adsorbed 95% of the fluoride that was produced by mineralization of 1.39 mM TFP. The kinetics and isotherms of adsorption were examined to determine the fluoride removal efficiency of BT-4 which co-existed with the sulfate ions from the consumed sulfate radicals. Accordingly, the kinetics of adsorption was described by a pseudo-second-order rate model, while the adsorption isotherms were well fitted with the Langmuir model. BT-4 had a high adsorption capacity of 26.4 mg g(-1) (25°C) in removing the fluoride from TFP mineralization, suggesting that the co-existing sulfate ions never significantly affected the fluoride removal efficiency. PMID:22947256

Shih, Yu-Jen; Putra, Widha Nirwana; Huang, Yao-Hui; Tsai, Jie-Cheng

2012-11-01

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

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...

63

Removal of dinitrotoluenes in wastewater by sono-activated persulfate.  

PubMed

Oxidative degradation of dinitrotoluenes (DNTs) in wastewater was performed using persulfate anions combined with ultrasonic irradiation, wherein a synergistic effect is observed. The batch-wise experiments were carried out to elucidate the influence of various operating parameters on sono-activated persulfate oxidation, including ultrasonic power intensity, persulfate anion concentration, reaction temperature and acidity of wastewater. It is noteworthy that the nitrotoluene contaminants could be almost completely eliminated by virtue of sono-activated persulfate oxidation, wherein sulfate radicals serve as principal oxidants, of which amounts are significantly enhanced via addition of sodium sulfate. Based on the results given by gas chromatograph-mass spectrometer (GC-MS), it is postulated that the methyl group of DNTs preliminarily underwent oxidation pathway into dinitrobenzoic acid, followed by decarboxylation to form 1,3-dinitrobenzene (DNB). In sum, the sono-activated persulfate oxidation is a promising method for treatment of nitrotoluenes in wastewater. PMID:22243771

Chen, Wen-Shing; Su, Yi-Chang

2012-07-01

64

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

65

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

PubMed

Iron oxide-immobilized manganese oxide (MnO2) composite was prepared and the reactivity of persulfate (PS) with the composite as activator was investigated for degradation of carbon tetrachloride and benzene at various pH levels. Brunauer-Emmett-Teller (BET) surface area of the composite was similar to that of pure MnO2 while the pore volume and diameter of composite was larger than those of MnO2. Scanning electron microscopy couples with energy dispersive spectroscopy (SEM-EDS) showed that Fe and Mn were detected on the surface of the composite, and X-ray diffraction (XRD) analysis indicated the possibilities of the existence of various iron oxides on the composite surface. Furthermore, the analyses of X-ray photoelectron (XPS) spectra revealed that the oxidation state of iron was identified as 1.74. In PS/composite system, the same pH for the highest degradation rates of both carbon tetrachloride and benzene were observed and the value of pH was 9. Scavenger test was suggested that both oxidants (i.e. hydroxyl radical, sulfate radical) and reductant (i.e. superoxide anion) were effectively produced when PS was activated with the iron-immobilized MnO2. PMID:24184048

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

2014-01-01

66

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

67

Occupational non-immediate type allergic asthma due to ammonium persulfate.  

PubMed

While numerous cases of immediate-type occupational asthma due to persulfates with positive skin prick test reactions to ammonium persulfate are well documented, few non-immediate type reactions have been described in the literature. We report the case of an atopic worker who developed work-related asthmatic symptoms shortly after he began his job in persulfate production. The diagnosis of asthma was corroborated by methacholine testing. The patient showed a positive patch test reaction to ammonium persulfate, while skin prick test was negative. He presented an isolated late symptomatic airway obstruction after a cumulative dose of 0.6 mg ammonium persulfate administered by a dosimeter method. An immunologic mechanism was demonstrated by a significant increase in exhaled nitric oxide and the number of eosinophils in induced sputum. These findings suggest that isolated late bronchial reactions to persulfates are mediated by eosinophilic inflammatory responses. PMID:22826052

Polychronakis, Ioannis; Thanasias, Efthimios; Raulf-Heimsoth, Monika; Merget, Rolf

2013-01-01

68

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

69

LaCoO3 acting as an efficient and robust catalyst for photocatalytic water oxidation with persulfate.  

PubMed

Cobalt-containing metal oxides [perovskites (LaCoO(3), NdCoO(3), YCoO(3), La(0.7)Sr(0.3)CoO(3)), spinel (Co(3)O(4)) and wolframite (CoWO(4))] have been examined as catalysts for photocatalytic water oxidation with Na(2)S(2)O(8) and [Ru(bpy)(3)](2+) as an electron acceptor and a photosensitizer, respectively. Catalysts with the perovskite structure exhibited higher catalytic activity as compared with the catalysts with the spinel and wolframite structures. LaCoO(3), which stabilizes Co(III) species in the perovskite structure, exhibited the highest catalytic activity in the photocatalytic water oxidation compared with CoWO(4), Co(3)O(4) and La(0.7)Sr(0.3)CoO(3) which contain Co(II) or Co(IV) species in the matrices. The high catalytic reactivity of LaCoO(3) possessing perovskite structure was maintained in NdCoO(3) and YCoO(3) which exclusively contain Co(III) species. Thus, the catalytic activity of Co ions can be controlled by the additional metal ions, which leads to development of highly reactive and robust catalysts for the photocatalytic water oxidation. PMID:22415556

Yamada, Yusuke; Yano, Kentaro; Hong, Dachao; Fukuzumi, Shunichi

2012-04-28

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

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

72

Removal effectiveness and mechanisms of naphthalene and heavy metals from artificially contaminated soil by iron chelate-activated persulfate.  

PubMed

The effectiveness and mechanisms of naphthalene and metal removal from artificially contaminated soil by FeEDTA/FeEDDS-activated persulfate were investigated through batch experiments. Using FeEDTA-activated persulfate, higher naphthalene removal from the soil at 7 h was achieved (89%), compared with FeEDDS-activated persulfate (75%). The removal was mainly via the dissolution of naphthalene partitioned on mineral surfaces, followed by activated persulfate oxidation. Although EDDS is advantageous over EDTA in terms of biodegradability, it is not preferable for iron chelate-activated persulfate oxidation since persulfate was consumed to oxidize EDDS, resulting in persulfate inadequacy for naphthalene oxidation. Besides, 55 and 40% of naphthalene were removed by FeEDTA and FeEDDS alone, respectively. Particularly, 21 and 9% of naphthalene were degraded in the presence of FeEDTA and FeEDDS alone, respectively, which caused by electrons transfer among dissolved organic matter, Fe(2+)/Fe(3+) and naphthalene. Over 35, 36 and 45% of Cu, Pb and Zn were removed using FeEDTA/FeEDDS-activated persulfate. PMID:23523688

Yan, Dickson Y S; Lo, Irene M C

2013-07-01

73

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

74

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

75

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

76

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

77

Electrolytic manipulation of persulfate reactivity by iron electrodes for trichloroethylene degradation in groundwater.  

PubMed

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/m(3) ? Iv ? 244 A/m(3)) where k1 and Iv are the pseudo first-order rate constant (min(-1)) and volume normalized current (A/m(3)), respectively. Persulfate is mainly decomposed by Fe(2+) produced from the electrochemical and chemical corrosion of iron followed by the regeneration via Fe(3+) reduction on the cathode. SO4(•-) and ·OH cocontribute 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

78

New Anode Materials for Electrolytic Persulfate Formation.  

National Technical Information Service (NTIS)

Novel carbon-based electrode materials were prepared by a surface modification technique known as specific fluorination for use as anodes in the electrolytic production of persulfates. The specific fluorination process creates a stabilized form of carbon ...

N. L. Weinberg

1988-01-01

79

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

80

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

PubMed Central

This study explored the potential use of a sulfate radical (SO·?4)-based photochemical oxidation process to treat the commercial nonionic surfactant octylphenol polyethoxylate (OPPE) Triton™ X-45. For this purpose, the effect of initial S2O2?8 (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 S2O2?8 concentrations (?2.5 mM). S2O2?8/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 S2O2?8. On the other hand, TOC removal efficiencies dropped down to only 40% under the same reaction conditions. S2O2?8/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 S2O2?8/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 SO·?4 and HO·, bimolecular reaction rate coefficients of OPPE with SO·?4 and HO· were determined by employing competition kinetics with aqueous phenol (47 ?M) selected as the reference compound. The pseudo-first-order abatement rate coefficient obtained for OPPE during S2O2?8/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 pseudo-first-order abatement rate coefficients were obtained for both OPPE (0.087 min?1) and phenol (0.140 min?1). From the kinetic study, second-order reaction rate coefficients for OPPE with SO·?4 and HO· were determined as 9.8 × 108 M?1 s?1 and 4.1 × 109 M?1 s?1, respectively. The kinetic study also revealed that the selectivity of SO·?4 was found to be significantly higher than that of HO·.

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

2013-01-01

81

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

PubMed

This study explored the potential use of a sulfate radical (SO(·-) 4)-based photochemical oxidation process to treat the commercial nonionic surfactant octylphenol polyethoxylate (OPPE) Triton™ X-45. For this purpose, the effect of initial S2O(2-) 8 (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 S2O(2-) 8 concentrations (?2.5 mM). S2O(2-) 8/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 S2O(2-) 8. On the other hand, TOC removal efficiencies dropped down to only 40% under the same reaction conditions. S2O(2-) 8/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 S2O(2-) 8/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 SO(·-) 4 and HO(·), bimolecular reaction rate coefficients of OPPE with SO(·-) 4 and HO(·) were determined by employing competition kinetics with aqueous phenol (47 ?M) selected as the reference compound. The pseudo-first-order abatement rate coefficient obtained for OPPE during S2O(2-) 8/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 pseudo-first-order abatement rate coefficients were obtained for both OPPE (0.087 min(-1)) and phenol (0.140 min(-1)). From the kinetic study, second-order reaction rate coefficients for OPPE with SO(·-) 4 and HO(·) were determined as 9.8 × 10(8) M(-1) s(-1) and 4.1 × 10(9) M(-1) s(-1), respectively. The kinetic study also revealed that the selectivity of SO(·-) 4 was found to be significantly higher than that of HO(·). PMID:24790933

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

2013-01-01

82

Modification of indium tin oxide with persulfate-based photochemistry toward facile, rapid, and low-temperature interface-mediated multicomponent assembling.  

PubMed

The well-controlled material assembly and patterning on indium tin oxide (ITO) coating layer is of great importance for the practical fabrication of a functional device. Nonetheless, the conventional way to achieve this aim is still mainly based on the combination of photolithography with pattern transfer techniques (e.g., wet/dry etching, ?CP) due to the lack of one method that is able to directly afford site-selective ITO surface tailoring and subsequent templating for material assembly. Herein, we reported a novel, fast, and efficient photochemical reaction to accurately tailor the surface property of ITO with light-controlled site-selectivity, thus resulting in direct photoresist-free and etching/contact-free lithographic patterning of building blocks, e.g., ZnO, BaTiO3, CdS, lipid membrane, conductive polymers, colloids, and liquid crystals. The entire process reveals new interfacial chemistry suitable for inorganic metal oxide and its important versatile implications for low-cost fabrication of large-area flat and flexible optical/electronic/biorelated devices. PMID:24716839

Mu, Xiaoyan; Guo, Shulei; Zhang, Linyuan; Yang, Peng

2014-05-01

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

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

85

Competition by aquifer materials in a bimetallic nanoparticle/persulfate system for the treatment of trichloroethylene.  

PubMed

It has been suggested in the literature that aquifer materials can compete with the target organic compounds in an activated peroxygen system. In this study, we employed a rapid treatment method using persulfate activated with bimetallic nanoparticles to investigate the competition between aquifer materials and the dissolved phase of a target organic compound. The concentration of dissolved trichloroethylene (TCE) remaining after using the activated persulfate system was two- to three-fold higher in a soil slurry batch system than in an aqueous batch system. For all five aquifer materials investigated, an increase in the mass of the aquifer solids significantly decreased the degradation of TCE. A linear relationship was observed between the mass of aquifer materials and the initial TCE degradation rate, suggesting that the organic carbon and/or aquifer material constituents (e.g., carbonates and bicarbonates) compete with the oxidation of TCE. PMID:23949733

Al-Shamsi, Mohammed Ahmad; Thomson, Neil R

2013-10-01

86

Degradation of diphenylamine by persulfate: Performance optimization, kinetics and mechanism.  

PubMed

The degradation of diphenylamine (DPA) in aqueous solution by persulfate is investigated. Effects of pH, persulfate concentration, ionic strength, temperature and catalytic ions Fe(3+) and Ag(+) on the degradation efficiency of DPA by persulfate are examined in batch experiments. The degradation of DPA by persulfate is found to follow the pseudo-first-order kinetic model. Increasing the reaction temperature or persulfate concentration may significantly accelerate the DPA degradation. Fe(3+) and Ag(+) ions can enhance the degradation of DPA, and Ag(+) ion is more efficient than Fe(3+) ion. However, the increase of either the pH value or ionic strength will decrease the rate of DPA degradation. N-Phenyl-4-quinoneimine, N-carboxyl-4-quinoneimine, 4-quinoneimine and oxalic acid are identified as the major intermediates of DPA degradation, and a primary pathway for the degradation of DPA is proposed. The degradation of DPA in surface water, groundwater and seawater is also tested by persulfate, and more than 90% of DPA can be degraded at room temperature in 45min at an initial concentration of 20mgL(-1). PMID:18774644

Li, Shen-Xin; Wei, Dong; Mak, Nai-Ki; Cai, ZongWei; Xu, Xiang-Rong; Li, Hua-Bin; Jiang, Yue

2009-05-15

87

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

Federal Register 2010, 2011, 2012, 2013

...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

88

Degradation of carbamazepine by Fe(II)-activated persulfate process.  

PubMed

Experimental studies were conducted to investigate the oxidative degradation of carbamazepine (CBZ), one of the most frequently detected pharmaceuticals in various waters, by Fe(II)-activated persulfate process. Results show that the Fe(2+)/S2O8(2-) process is very effective for the elimination of CBZ and characterized by a two-stage kinetics (a rapid initial decay followed by a retardation stage). CBZ degradation reaction was observed to be pH dependent and the optimum pH is 3.0 in the range of 2.00-7.87. The concentration of Fe(2+) and S2O8(2-) exhibited a noticeable influence on CBZ removal efficiency, where [S2O8(2-)] exerted more significant effects than that of [Fe(2+)]. The optimal molar ratio of CBZ, Fe(2+), and S2O8(2-) is found to be 1:5:40. The effect of various inorganic anions on CBZ removal was also evaluated under the optimal conditions. The anions NO3(-), SO4(2-) and H2PO4(-)caused a negative effect on the performance of this process, while Cl(-) interestingly accelerated CBZ degradation. The higher the Cl(-) concentration, the faster the CBZ decay rate. The intermediates were identified during CBZ degradation with and without the presence of Cl(-). The evolution of intermediates for these two scenarios was compared. The decay pathways of CBZ were proposed accordingly. PMID:24462988

Rao, Y F; Qu, Liang; Yang, Haisong; Chu, W

2014-03-15

89

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

Federal Register 2010, 2011, 2012, 2013

...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

90

Transformation of polychlorinated biphenyls by persulfate at ambient temperature.  

PubMed

Increasing attention has been paid to persulfate due to its high efficiency in degrading organic pollutants. This paper investigated the transformation of a selected polychlorinated biphenyl (PCB) by sodium persulfate without activators at near ambient temperature (10-40°C). The results showed that 2,4,4'-CB was completely decomposed by persulfate at 30°C in 8 h. The products were identified by gas chromatography-mass spectrometry (GC-MS), and transformation pathways could be divided into two steps as dechlorination and hydroxylation. Electron paramagnetic resonance (EPR) technique was used to identify the generated radical species at different pH values at ambient temperature. The results showed that sulfate radicals (SO(4)(•-)) were predominant under acidic condition and hydroxyl radicals ((•)OH) were predominant under basic condition. This behavior was also confirmed by the quenching studies and kinetic model. Decreasing the solution pH resulted in increasing the degradation efficiency of 2,4,4'-CB. Moreover, the degradation of other PCBs such as 2-CB, 4-CB, 2,4-CB, 2,4'-CB, and 2,4,6-CB with persulfate was examined. The findings of this study can provide guidance in the remediation of PCBs contaminated soil and water with persulfate. PMID:22921645

Fang, Guo-Dong; Dionysiou, Dionysios D; Zhou, Dong-Mei; Wang, Yu; Zhu, Xiang-Dong; Fan, Jian-Xin; Cang, Long; Wang, Yu-Jun

2013-02-01

91

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

92

Reversible formation of ammonium persulfate/sulfuric acid graphite intercalation compounds and their peculiar Raman spectra.  

PubMed

Graphite intercalation compounds (GICs) can be considered stacks of individual doped graphene layers. Here we demonstrate a reversible formation of sulfuric acid-based GICs using ammonium persulfate as the chemical oxidizing agent. No covalent chemical oxidation leading to the formation of graphite oxide occurs, which inevitably happens when other compounds such as potassium permanganate are used to charge carbon layers. The resulting acid/persulfate-induced stage-1 and stage-2 GICs are characterized by suppression of the 2D band in the Raman spectra and by unusually strong enhancement of the G band. The G band is selectively enhanced at different doping levels with different excitations. These observations are in line with recent reports for chemically doped and gate-modulated graphene and support newly proposed theories of Raman processes. At the same time GICs have some advantageous differences over graphene, which are demonstrated in this report. Our experimental observations, along with earlier reported data, suggest that at high doping levels the G band cannot be used as the reference peak for normalizing Raman spectra, which is a commonly used practice today. A Fermi energy shift of 1.20-1.25 eV and ?1.0 eV was estimated for the stage-1 and stage-2 GICs, respectively, from the Raman and optical spectroscopy data. PMID:22880798

Dimiev, Ayrat M; Bachilo, Sergei M; Saito, Riichiro; Tour, James M

2012-09-25

93

Persulfates from China. Investigation No. 731-TA-749 (Second Review).  

National Technical Information Service (NTIS)

In June 1997, the Commission determined that an industry in the United States was materially injured by reason of imports of persulfates from China that Commerce determined to be sold at less than fair value. Commerce issued its antidumping duty order in ...

2008-01-01

94

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

95

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

96

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

97

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

98

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

99

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

100

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

Federal Register 2010, 2011, 2012, 2013

...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

101

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

Federal Register 2010, 2011, 2012, 2013

...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

102

Promoted degradation of perfluorooctanic acid by persulfate when adding activated carbon.  

PubMed

Treatment of persistent perfluorooctanoic acid (PFOA) in water using persulfate (PS) oxidation typically requires an elevated temperature or UV irradiation, which is energy-consuming. Under relatively low temperatures of 25-45°C, activated carbon (AC) activated PS oxidation of PFOA was evaluated for its potential of practical applications. With presence of AC in PS oxidation, PFOA removal efficiency at 25°C reached 682% with a high defluorination efficiency of 549% after 12h and few intermediates of short-chain perfluorinated carboxylic acids (PFCAs) were found. The removal and defluorination rates with the combined AC/PS system were approximately 12 and 19 times higher than those of the PS-only system, respectively. Activated carbon not only removes PFOA through adsorption, but also activates PS to form sulfate radicals that accelerate the decomposition and mineralization of PFOA. The activation energy for PS oxidation of PFOA was reduced from 668 to 261kJ/mol by the catalytic effect of AC, which implies a lower reaction temperature and a shorter reaction time would suffice. A 2-cycle schematic reaction mechanism was used to describe PS oxidation of PFOA with the generation of various intermediates and end-products. PMID:23978721

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

2013-10-15

103

Metal free sulfenylation and bis-sulfenylation of indoles: persulfate mediated synthesis.  

PubMed

A method which avoids metal and halogen for the synthesis of 3-arylthioindoles from indoles and diaryl disulfides using ammonium persulfate in methanol has been presented. Moreover, double C-H sulfenylation of indoles at 2 and 3-positions has also been achieved using iodine and ammonium persulfate. PMID:24166084

Prasad, Ch Durga; Kumar, Shailesh; Sattar, Moh; Adhikary, Amit; Kumar, Sangit

2013-12-14

104

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

Federal Register 2010, 2011, 2012, 2013

...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

105

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

Federal Register 2010, 2011, 2012, 2013

...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

106

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

...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

107

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

Federal Register 2010, 2011, 2012, 2013

...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

108

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

Federal Register 2010, 2011, 2012, 2013

...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

109

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

...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

110

Fe/S doped granular activated carbon as a highly active heterogeneous persulfate catalyst toward the degradation of Orange G and diethyl phthalate.  

PubMed

Fe/S doped granular activated carbon (Fe/SGAC) was synthesized with ferric nitrate, Na2S2O3 and (NH4)2S2O8 via an impregnation-precipitation, reduction-oxidation combining with aqueous-phase synthesis method treatment. Surface density of functional groups, surface area changes as well as the chemical state inside Fe/SGAC catalyst were studied by Boehm titration, N2 adsorption and X-ray photoelectron spectroscopy (XPS). The reactivity of the catalysts was tested by degrading Orange G (OG) and diethyl phthalate (DEP). The Fe/SGAC catalysts could significantly enhance the removal rate of OG as compared to persulfate alone and PS/GAC. And the catalytic capacity was also enhanced by S doping. But the degradation of DEP under the similar condition was inhibited by adsorption process because of the different hydrophobicities of OG and DEP molecule. Fe2O3/FeOOH (Fe(3+)) (represents ferrihydrite) together with FeO/Fe3O4 (Fe(2+)) and Fe2O3-satellite, which provide the new active site for persulfate catalyst was found to be the major components of iron element in Fe/SGAC catalyst; the existence of FeS2(S(-)) for sulfur element verified the assumption that the doped S element promoted the electron transfer between the persulfate species and iron oxide at the interface. COD removal experiment further confirmed that mostly contaminant removal was owed to the Fe/SGAC catalytic persulfate oxidation process. PMID:24461853

Pu, Mengjie; Ma, Yongwen; Wan, Jinquan; Wang, Yan; Huang, Mingzhi; Chen, Yangmei

2014-03-15

111

[Degradation of the absorbed methyl mercaptan by persulfate in alkaline solution].  

PubMed

Methyl mercaptan (CH3SH) is considered to be an important contributor to odors. It is a toxic, corrosive and acid gas. The absorption of CH3SH by alkaline solution is one of the most widely used processes, but the remained solution should be further treated. The degradation of dissolved CH3S- by persulfate (PS) oxidation has not been reported. CH3SH is absorbed in alkaline solution and degraded by PS oxidation using a recycling continuous system for absorption and degradation. The stability of PS under alkaline conditions is discussed. The influence of different reaction conditions on the absorption rate and degradation rate is also studied. It was observed that PS was relatively stability under alkaline conditions and the dissolved CH3S- could be degraded effectively by PS. The absorption rate of CH3SH first increased and then decreased with the increasing concentration of PS. The degradation rate of CH3S- increased with the increasing concentration of PS. It was also observed that the efficiency between absorption and degradation had been significantly increased with the increasing of pH. In the conditions of pH = 12, fixed CH3SH concentration of 80 mg x m(-3) with a fixed gas flow rate of 1.5 L x min(-1), 1.4 g x L(-1) PS, 90% of the dissolved CH3S- can be degraded. PMID:24455922

Yang, Shi-Ying; Wang, Lei-Lei; Feng, Lin-Yu; Zhao, La-Juan; Shi, Chao

2013-11-01

112

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

113

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

114

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.  

National Technical Information Service (NTIS)

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 persul...

D. Craig S. A. Holditch

1993-01-01

115

Degradation of bisphenol A in aqueous solution by persulfate activated with ferrous ion.  

PubMed

Degradation of bisphenol A (BPA) in aqueous solution was studied with high-efficiency sulfate radical (SO4(-·)), which was generated by the activation of persulfate (S2O8(2-)) with ferrous ion (Fe(2+)). S2O8(2-) was activated by Fe(2+) to produce SO4(-·), and iron powder (Fe(0)) was used as a slow-releasing source of dissolved Fe(2+). The major oxidation products of BPA were determined by liquid chromatography-mass spectrometer. The mineralization efficiency of BPA was monitored by total organic carbon (TOC) analyzer. BPA removal efficiency was improved by the increase of initial S2O8(2-) or Fe(2+) concentrations and then decreased with excess Fe(2+) concentration. The adding mode of Fe(2+) had significant impact on BPA degradation and mineralization. BPA removal rates increased from 49 to 97% with sequential addition of Fe(2+), while complete degradation was observed with continuous diffusion of Fe(2+), and the latter achieved higher TOC removal rate. When Fe(0) was employed as a slow-releasing source of dissolved Fe(2+), 100% of BPA degradation efficiency was achieved, and the highest removal rate of TOC (85%) was obtained within 2 h. In the Fe(0)-S2O8(2-) system, Fe(0) as the activator of S2O8(2-) could offer sustainable oxidation for BPA, and higher TOC removal rate was achieved. It was proved that Fe(0)-S2O8(2-) system has perspective for future works. PMID:23322415

Jiang, Xiaoxuan; Wu, Yanlin; Wang, Peng; Li, Hongjing; Dong, Wenbo

2013-07-01

116

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

117

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

118

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

119

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

120

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

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

Laser flash photolysis of sodium persulfate in aqueous solution with additions of dimethylformamide  

Microsoft Academic Search

The method of laser flash photolysis with excitation at 308nm was used to study the photochemistry of persulfate-ion in aqueous solutions with additions of N,N-dimethylformamide (DMF). The photolysis of S2O82? in water gives rise to SO4? radical anions with a 0.55 quantum yield. The rate constant of SO4? recombination was measured (2k=(2.7±0.2)×109M?1s?1 at ionic strength ?=0.9M). In the presence of

K. L Ivanov; E. M Glebov; V. F Plyusnin; Yu. V Ivanov; V. P Grivin; N. M Bazhin

2000-01-01

124

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

125

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

126

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

127

Chemical modification of chitin by grafting with polystyrene using ammonium persulfate initiator.  

PubMed

Chitin was successfully grafted with polystyrene by free radical mechanism using ammonium persulfate (APS) initiator. The reaction was carried out in aqueous medium. The effect of pH, chitin:monomer weight ratio, APS, reaction time and reaction temperature were investigated. The results showed that the optimum conditions for grafting of polystyrene were found as follows: pH 7, chitin:monomer weight ratio of 1:3, 0.4 g of APS, reaction temperature of 60 °C and reaction time 2 h. The graft copolymer was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and differential scanning electron microscopy (DSC). Gel permeation chromatography (GPC) analysis carried out on the hydrolyzed graft copolymer showed that the Mn and Mw were 6.3395×10(4) g/mol and 1.69283×10(5) g/mol, respectively, with polydispersity index of 2.7. PMID:24053848

Abu Naim, Ahmedy; Umar, Abdulganiyu; Sanagi, Mohd Marsin; Basaruddin, Noraimi

2013-11-01

128

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

129

Heat-activated cooling devices: A guidebook for general audiences.  

National Technical Information Service (NTIS)

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...

G. Wiltsee

1994-01-01

130

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

131

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

132

Friedel-Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis  

PubMed Central

Friedel-Crafts amidoalkylation was achieved by oxidation of dialkylamides using persulfate (S2O82?) in the presence of the visible light catalyst, Ru(bpy)3Cl2, at room temperature, via a reactive N-acyliminium intermediate. Alternatively, mild heating of the dialkylamides and persulfate afforded a metal and Lewis acid-free Friedel-Crafts amidoalkylation. Alcohols and electron–rich arenes served as effective nucleophiles, forming new C–O or C–C bonds. In general, photocatalysis provided higher yields and better selectivities.

Dai, Chunhui; Meschini, Francesco; Narayanam, Jagan M. R.; Stephenson, Corey R. J.

2012-01-01

133

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

134

Wet-oxidation and automated colorimetry for simultaneous determination of organic carbon, nitrogen and phosphorus dissolved in seawater  

Microsoft Academic Search

We developed a simple and reliable method which allows simultaneous determination of organic forms of carbon (DOC), nitrogen (DON) and phosphorus (DOP) dissolved in seawater. Conversion of dissolved organic matter (DOM) to inorganic products (carbon dioxide, nitrate+nitrite and soluble reactive phosphate) is performed by a persulfate wet-oxidation in low alkaline condition. After oxidation, the concentration of the inorganic products dissolved

Patrick Raimbault; Wilfried Pouvesle; Frédéric Diaz; Nicole Garcia; Richard Sempéré

1999-01-01

135

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

136

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

137

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

138

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...

139

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

140

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

141

The heat-activated stapes prosthesis 'SMart' Piston: technique and preliminary results.  

PubMed

Since 2003 we are using in our stapedotomies the Nitinol 'Smart' Piston. This prosthesis has a Teflon 'vestibular' end and a wire shaft made by Nitinol, with a heat activated self-crimping loop. Nitinol is an alloy of Nickel + Titanium, belonging to the class of the so-called smart materials, i.e. materials with shape-memory and superelastic properties. Nitinol is lightweight and highly biocompatible thanks to the thin layer of Titanium oxide covering the Nickel surface. The special advantage of this piston is that the loop grips by itself very uniformly and quite tightly around the incudal process or the malleus handle when a minimal heating (about 60 degrees C) is applied using a disposable heater ('Thermal Tip'). This piston was successfully used in our Department between 2003 and 2004 in a first group of 42 cases of stapedotomy and in 7 cases of malleostapedotomy. The shape and the uniformity of the loop grip was controlled by examining fresh temporal bone specimens by S.E.M. (x21 / 166) and in all specimens the loop was uniformly surrounding the ossicle, without 'dead' spaces. It is our feeling that this prosthesis is very useful in stapes surgery for at least two reasons: 1. because it improves the quality of the interface 'piston loop/long process of incus'; 2. because the duration of the procedure is reduced. PMID:17245045

Babighian, Gregorio; Fontana, Marco; Caltran, Silvia; Ciccolella, Michele; Amadori, Maurizio; De Zen, Michela

2007-01-01

142

Potential for in situ chemical oxidation of acid extractable organics in oil sands process affected groundwater.  

PubMed

The process of bitumen extraction from oil sands in Alberta, Canada leads to an accumulation of toxic acid-extractable organics (AEOs) in oil sands process water (OSPW). Infiltration of OSPW from tailings ponds and from their retaining sand dykes and subsequent transport towards surface water has occurred. Given the apparent lack of significant natural attenuation of AEOs in groundwater, remediation may be required. This laboratory study evaluates the potential use of unactivated persulfate and permanganate as in situ oxidation agents for remediation of AEOs in groundwater. Naphthenic acids (NAs; CnH2n+zO2), which are a component of the acutely toxic AEOs, were degraded by both oxidants in OSPW samples. Permanganate oxidation yielded some residual dissolved organic carbon (DOC) whereas persulfate mineralized the AEO compounds with less residual DOC. Acid-extractable organics from oxidized OSPW had essentially no Microtox toxicity. PMID:24054134

Sohrabi, V; Ross, M S; Martin, J W; Barker, J F

2013-11-01

143

Hydrophilic magnetic polymer latexes. 2. Encapsulation of adsorbed iron oxide nanoparticles  

Microsoft Academic Search

The encapsulation of seed polymer particles coated by anionic iron oxide nanoparticles has been investigated using N-isopropylacrylamide as a main monomer, N,N-methylene bisacrylamide as a crosslinking agent, itaconic acid as a functional monomer and potassium persulfate as an anionic\\u000a initiator. The magnetic latexes obtained have been characterized with regard to particle size, iron oxide content and electrophoretic\\u000a mobility. All these

F. Sauzedde; A. Elaïssari; C. Pichot

1999-01-01

144

Approach to polysubstituted 4-pyridones from N-aryl acetoacetamides via a N to C 1,3-acyl migration mediated by sodium persulfate.  

PubMed

Mediated by sodium persulfate (Na(2)S(2)O(8)), a series of polysubstituted 4-pyridones were synthesized via self-condensation of N-aryl acetoacetamides, during which a novel N to C 1,3-acyl migration should be involved. The structure of 4-pyridone was unequivocally confirmed by X-ray diffraction analysis. However, the self-condensation of N-benzyl acetoacetamides under the same condition gave polysubstituted 2-pyridones instead of 4-pyridones. PMID:22849823

Zhang, Zhiguo; Fang, Shiliang; Liu, Qingfeng; Zhang, Guisheng

2012-09-01

145

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

146

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

147

Oxidation and Removal of 1,2,4Trichlorobenzene using Sodium Persulfate in a Sorption-Desorption Experiment  

Microsoft Academic Search

The sorptive and desorptive behavior of 1,2,4-Trichlorobenzene (TCB) was studied in a mixture of river sediments and TCB at\\u000a initial aqueous concentrations of 0.5, 4, and 21 mg\\/L. All experiments were performed at a temperature of 20?C and at pH 5.58. Grain size, fraction of organic carbon (FOC), and pH analyses were conducted to determine the initial condition\\u000a of the

Adam M. Barbash; George E. Hoag; Farhad Nadim

2006-01-01

148

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

149

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

150

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.

2014-01-01

151

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

PubMed

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

Asgari, Ghorban; Seidmohammadi, AbdolMotaleb; Chavoshani, Afsane

2014-01-01

152

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

153

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

154

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

Microsoft Academic Search

We have synthesized 1D nanowires of lithium nickel manganese oxides with two different crystal structures through the chemical oxidation reaction of solid-state precursor LiMn0.5Ni0.5O2 under hydrothermal condition. According to X-ray diffraction and elemental analyses, the nanowires obtained by persulfate treatments at 65 and 120°C crystallize with a hexagonal layered and an ?-MnO2-type structure, respectively, in which nickel and manganese ions

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

2006-01-01

155

Hypersensitivity angiitis caused by fumes from heat-activated photocopy paper.  

PubMed

A 53-year-old librarian had recurrent palpable purpura on her ankles and legs that was found to be caused by the fumes released from heat-activated photocopy paper at her place of employment. Behenic acid was identified as the responsible chemical component through a series of challenge studies that simulated her work exposure. Behenic acid, a fatty acid, is volatilized when heat-activated photocopy paper is developed. Absorption through the upper respiratory mucosa was the likely route of entry of this agent. The mechanism of this reaction is unclear. Skin biopsies, complement studies, and immune complex assays failed to confirm a type III immune response. Physicians should be aware that chemical fumes released from microfilm copying machines or other devices that use heat-activated photocopy paper may cause palpable purpura. PMID:6338790

Tencati, J R; Novey, H S

1983-03-01

156

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

157

Use of Calcium Dipicolinate for Enumeration of Total Viable Endospore Populations Without Heat Activation1  

PubMed Central

A method, based on germination with 50 mm CaCl2 and 40 mm sodium dipicolinate (Na2DPA), was developed for the determination of total viable counts of bacterial spores requiring heat activation. Incorporation of these germinating agents into Tryptone Glucose Extract Agar permitted plate-count enumeration of essentially 100% of Bacillus subtilis strain 5230 spores without a heat treatment. Other spore suspensions were surveyed for their response to CaCl2 and Na2DPA, and for the subsequent removal of the heat-activation requirement for enumeration of maximal populations.

Busta, F. F.; Ordal, Z. John

1964-01-01

158

Activating persulfate by Fe(0) 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

159

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

160

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

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; Toit, Lisa C du; Modi, Girish; Naidoo, Dinesh; Pillay, Viness

2012-01-01

161

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.

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

2012-01-01

162

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

163

Adsorption mechanism of cationic surfactants onto acid- and heat-activated sepiolites  

Microsoft Academic Search

Systematic adsorption tests were carried out to determine the uptake of typical quaternary amines, dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide and a primary amine, dodecylamine hydrochloride by sepiolite. Bottle adsorption tests conducted with untreated, acid- and heat-activated sepiolites exhibit two distinct regions. The first stage is characterized by low rate and governed through an ion exchange process between ammonium ions and

E Sabah; M Turan; M. S Çelik

2002-01-01

164

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

165

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.  

National Technical Information Service (NTIS)

This report describes USGS methods I-2650-03 and I-4650-03 for determining total nitrogen and total phosphorus in filtered and whole-water alkaline persulfate digests, respectively. All aspects of the methods are described, including sample preparation an...

C. J. Patton J. R. Kryskalla

2003-01-01

166

Adsorptive properties of acid-heat activated rectorite for Rhodamine B removal: equilibrium, kinetic studies  

Microsoft Academic Search

The acid-heat activated sodium rectorite (AH-R) was prepared and used to remove Rhodamine B (RhB) from aqueous solution. The AH-R showed higher adsorbility than the raw sodium rectorite and the rectorite modified by acid or by heat treatment. The effects of pH, adsorbent dosage, initial dye concentration, reaction temperature and ionic strength were studied. The Rhodamine B adsorption on the

Xiangheng Xue; Xisheng He; Yonghong Zhao

2012-01-01

167

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.

Cao, Xu; Ma, Linlin; Yang, Fan

2014-01-01

168

Heat Activation of Phycomyces blakesleeanus Spores: Thermodynamics and Effect of Alcohols, Furfural, and High Pressure  

PubMed Central

The thermodynamic parameters for the heat activation of the sporangiospores of Phycomyces blakesleeanus were determined. For the apparent activation enthalpy (?H#) a value of 1,151 kJ/mol was found, whereas a value of 3,644 J./°K·mol was calculated for the apparent activation entropy (?S#). n-Alcohols (from methanol to octanol), phenethyl alcohol, and furfural lowered the activation temperature of P. blakesleeanus spores. The heat resistance of the spores was lowered concomitantly. The effect of the alcohols was a linear function of the concentration in the range that could be applied. When the log of the concentration needed to produce an equal shift of the activation temperature was plotted for each alochol against the log of the octanol/water partition coefficient, a straight line was obtained. The free energy of adsorption of the n-alcohols to their active sites was calculated to be ?2,487 J/mol of CH2 groups. Although still inconclusive, this points toward an involvement of protein in the activation process. The effect of phenethyl alcohol was similar to the effect of n-alcohols, but furfural produced a greater shift than would be expected from the value of its partition coefficient. When the heat activation of the spores was performed under high pressure, the activation temperature was raised by 2 to 4°K/1,000 atm. However, with pressures higher than 1,000 atm (1.013 × 105 kPa) the activation temperature was lowered until the pressure became lethal (more than 2,500 atm). It is known that membrane phase transition temperatures are shifted upward by about 20°K/1,000 atm and that protein conformational changes are shifted upward by 2 to 6°K/1,000 atm. Consequently, heat activation of fungal spores seems to be triggered by a protein conformational change and not by a membrane phase transition. Activation volumes of ?54.1 cm3/mol at 38°C and ?79.3 cm2/mol at 40°C were found for the lowering effect of high pressure on the heat activation temperature.

Thevelein, Johan M.; Van Assche, Jozef A.; Carlier, Albert R.; Heremans, Karel

1979-01-01

169

Exploration of the role of heat activation in enhancing serpentine carbon sequestration reactions.  

PubMed

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 CO2 and at temperatures ranging from 100 to 125 degrees C. Carbonation reactivity is generally correlated with the extent of meta-serpentine formation and structural disorder. PMID:15669355

McKelvy, Michael J; Chizmeshya, Andrew V G; Diefenbacher, Jason; Béarat, Hamdallah; Wolf, George

2004-12-15

170

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

171

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

172

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

173

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

174

Superdormant spores of Bacillus species have elevated wet-heat resistance and temperature requirements for heat activation.  

PubMed

Purified superdormant spores of Bacillus cereus, B. megaterium, and B. subtilis isolated after optimal heat activation of dormant spores and subsequent germination with inosine, d-glucose, or l-valine, respectively, germinate very poorly with the original germinants used to remove dormant spores from spore populations, thus allowing isolation of the superdormant spores, and even with alternate germinants. However, these superdormant spores exhibited significant germination with the original or alternate germinants if the spores were heat activated at temperatures 8 to 15 degrees C higher than the optimal temperatures for the original dormant spores, although the levels of superdormant spore germination were not as great as those of dormant spores. Use of mixtures of original and alternate germinants lowered the heat activation temperature optima for both dormant and superdormant spores. The superdormant spores had higher wet-heat resistance and lower core water content than the original dormant spore populations, and the environment of dipicolinic acid in the core of superdormant spores as determined by Raman spectroscopy of individual spores differed from that in dormant spores. These results provide new information about the germination, heat activation optima, and wet-heat resistance of superdormant spores and the heterogeneity in these properties between individual members of dormant spore populations. PMID:19592590

Ghosh, Sonali; Zhang, Pengfei; Li, Yong-qing; Setlow, Peter

2009-09-01

175

Fast modulation of heat-activated ionic current by proinflammatory interleukin 6 in rat sensory neurons.  

PubMed

The pro-inflammatory cytokine interleukin-6 (IL-6) together with its soluble receptor (sIL-6R) induces and maintains thermal hyperalgesia. It facilitates the heat-induced release of calcitonin gene-related peptide from rat cutaneous nociceptors in vivo and in vitro. Here we report that exposure of nociceptive neurons to the IL-6-sIL-6R complex or the gp130-stimulating designer IL-6-sIL-6R fusion protein Hyper-IL-6 (HIL-6) resulted in a potentiation of heat-activated inward currents (I(heat)) and a shift of activation thresholds towards lower temperatures without affecting intracellular calcium levels. The Janus tyrosine kinase inhibitor AG490, the selective protein kinase C (PKC) inhibitor, bisindolylmaleimide 1 (BIM1), as well as rottlerin, a selective blocker of the PKCdelta isoform, but not the cyclooxygenase inhibitor indomethacin, effectively reduced the effect. Reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization revealed expression of mRNA for the signal-transducing beta subunit of the receptor gp130 in neuronal somata, rather than satellite cells in rat dorsal root ganglia. Together, the results suggest that IL-6-sIL-6R acts directly on sensory neurons. It increases their susceptibility to noxious heat via the gp130/Jak/PKCdelta signalling pathway. PMID:15817518

Obreja, O; Biasio, W; Andratsch, M; Lips, K S; Rathee, P K; Ludwig, A; Rose-John, S; Kress, M

2005-07-01

176

40 CFR 141.131 - Analytical requirements.  

Code of Federal Regulations, 2010 CFR

...or Standard Method 5310 C or 5310 C-00 (Persulfate-Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method 5310...or Standard Method 5310 C or 5310 C-00 (Persulfate-Ultraviolet or Heated- [[Page...

2009-07-01

177

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

178

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

PubMed

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

Bilgin Oncu, Nalan; Akmehmet Balcioglu, Isil

2013-10-01

179

A heat-activated MAP kinase (HAMK) as a mediator of heat shock response in tobacco cells.  

PubMed

A heat-activated MAP kinase (HAMK), immunologically related to the extracellular signal-regulated kinase (ERK) super-family of protein kinases, has been identified in BY2 cells of tobacco. The activation of HAMK at 37 degrees C was transient and detected within 2 min and reached a maximum level within 5 min. Ca(2+) chelators and channel blockers, and the known inhibitors of MEK, a MAP kinase kinase, prevented the heat activation of HAMK. This suggests that HAMK activation is part of a heat-triggered MAP kinase cascade that requires Ca(2+) influx. The heat shock protein HSP70 accumulated at 37 degrees C, but not when HAMK activation was prevented with the inhibitors of MEK or with Ca(2+) chelators or channel blockers. As previously shown for heat activation of HAMK, heat-induced accumulation of HSP70 requires membrane fluidization and reorganization of cytoskeleton. We concluded that heat-triggered HAMK cascade might play an essential role in the launching of heat shock response and hsp gene expression in tobacco cells. PMID:17996015

Suri, Sarabjeet S; Dhindsa, Rajinder S

2008-02-01

180

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

181

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

182

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

183

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

184

Polyaniline shell cross-linked Fe3O4 magnetic nanoparticles for heat activated killing of cancer cells.  

PubMed

Superparamagnetic Fe3O4 nanoparticles are appealing materials for heat activated killing of cancer cells. Here, we report a novel method to enhance the heat activated killing of cancer cells under an AC magnetic field (AMF) by introducing a polyaniline impregnated shell onto the surface of Fe3O4 nanoparticles. These polyaniline shell cross-linked magnetic nanoparticles (PSMN) were prepared by in situ polymerization of aniline hydrochloride on the surface of carboxyl PEGylated Fe3O4 nanoparticles. XRD and TEM analyses revealed the formation of single phase inverse spinel Fe3O4 nanoparticles of a size of about 10 nm. The successful growth of the polyaniline shell on the surface of carboxyl PEGylated magnetic nanoparticles (CPMN) is evident from FTIR spectra, DLS, TGA, zeta-potential and magnetic measurements. Both CPMN and PSMN show good colloidal stability, superparamagnetic behavior at room temperature and excellent heating efficacy under AMF. It has been observed that the heating efficacy of PSMN under AMF was slightly reduced as compared to that of CPMN. The enhanced toxicity of PSMN to cancer cells under AMF suggests their strong potential for magnetic hyperthermia. Furthermore, PSMN shows high loading affinity for an anticancer drug (doxorubicin), its sustained release and substantial internalization in tumor cells. PMID:24948377

Rana, Suman; Jadhav, Neena V; Barick, K C; Pandey, B N; Hassan, P A

2014-07-22

185

Chemical oxidation of ibuprofen in the presence of iron species at near neutral pH.  

PubMed

The objective of this work was to evaluate the removal of ibuprofen (IBP) using the oxidants hydrogen peroxide (H(2)O(2)) and sodium persulfate (Na(2)S(2)O(8)). The ability of magnetite (Fe(3)O(4)) to activate persulfate (PS) and H(2)O(2) for the oxidation of IBP at near neutral pH was evaluated as well. The use of soluble Fe(2+) to activate H(2)O(2) and Na(2)S(2)O(8) was also investigated. H(2)O(2) and Na(2)S(2)O(8) were inactive during the sixty-minute experiments when used alone. However, activation using Fe(2+) increased the removal to 95% in the presence of H(2)O(2) (Fenton reaction) and 63% in the presence of Na(2)S(2)O(8) at pH 6.6. Chemical oxygen demand (COD) removal was also greater for Fenton oxidation (65%) than for iron-activated PS oxidation (25%). Activation of H(2)O(2) and PS by Fe(3)O(4) was only observed at a high oxidant concentration and over 48 h of reaction time. A second order rate kinetic constant was determined for H(2)O(2) (3.0?10(-3) M(-1) s(-1)) and Na(2)S(2)O(8) (1.59?10(-3) M(-1) s(-1)) in the presence of Fe(3)O(4). Finally, several of the degradation products formed during oxidation of IBP in the presence of H(2)O(2) and Na(2)S(2)O(8) (activated by Fe(2+)) were identified. These include oxalic acid, pyruvic acid, formic acid, acetic acid, 4-acetylbenzoic acid, 4-isobutylacetophenone (4-IBAP) and oxo-ibuprofen. PMID:22578697

Sabri, N; Hanna, K; Yargeau, V

2012-06-15

186

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

187

Abatement of waste-water biorefractory organics via electro-oxidative treatment.  

PubMed

The electrochemical oxidation of coumaric acid, a biorefractory compound present in several industrial waste waters, has been investigated by use of Pt-Ti anodes and at electrolyte concentration (0.02 N NaCl or Na2SO4) low enough to allow direct dischargeability of the waste water into superficial water basins according to the Italian law (DL 152/11-5-99). Particularly, the role of the electrolyte over the conversion rate has been assessed. The obtained results show that the oxidation process should take place both at the electrode surface and in the bulk of the solution, via electrochemically-generated oxidising species (H2O2, persulfates, Cl2, NaClO). The faster coumaric acid abatement rates were found with chloride based electrolytes, which, however, lead to the formation of non-biodegradable small-molecular-weight chlorinated hydrocarbons. PMID:11381547

Saracco, G; Aigotti, R; Solarino, L; Specchia, V; Maja, M

2001-01-01

188

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

189

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

190

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 ...

191

An integrated approach for Cr(VI)-detoxification with polyaniline/cellulose fiber composite prepared using hydrogen peroxide as oxidant.  

PubMed

In this short communication, the demonstration of a new integrated process concept involving the use of a bio-based material for detoxification of Cr(VI)-contaminated water is presented. Specifically, the bio-based material is a polyaniline/cellulose fiber composite prepared by in situ polymerization of aniline in the presence of cellulose fibers, using the industrially favorable hydrogen peroxide (instead of costly oxidants such as ammonium persulfate) as the oxidant. Ferric chloride was used to catalyze the polymerization reaction. The process conditions for the preparation of the composite were preliminarily optimized, and the proposed concept was demonstrated. Under the conditions studied, the use of the composite was quite effective in the detoxification of the model solution. The proposed concept may serve as an alternative approach for water treatment using renewable materials. PMID:23010214

Liu, Xiangyao; Qian, Xueren; Shen, Jing; Zhou, Wanpeng; An, Xianhui

2012-11-01

192

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

193

Small-angle neutron scattering study of activated carbon cloth and ammonium persulfate-modified activated carbon cloth: Effect of oxygen content  

NASA Astrophysics Data System (ADS)

Small-angle neutron scattering (SANS) patterns of as-received, oxidized, and thermally reduced FM1/250 activated carbon cloth (ACC) samples are compared to determine the effects of surface chemistry on scattering. Porosity analyses show minimal effect on pore size distribution from oxidation, but an increase in micropore volume on heat treatment. SANS suggests an increase in localized order within the treated samples when compared with graphite cloth patterns. The ACC exhibits Porod scattering at q-ranges<0.3 nm -1; the graphite cloth exhibits the same at q-ranges>1.0 nm -1. A cylindrical model reproduces the scattering patterns in the micropore equivalent dimensions, q>0.5 nm -1.

Pendleton, Phillip; Chen, Lin

2006-11-01

194

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

PubMed

To improve the coupling of in situ chemical oxidation and in situ bioremediation, a systematic analysis was performed of the effect of chemical oxidation with Fenton's reagent, modified Fenton's reagent, permanganate, or persulfate, on microbial diversity and activity during 8 weeks of incubation in two diesel-contaminated soils (peat and fill). Chemical oxidant and soil type affected the microbial community diversity and biodegradation activity; however, this was only observed following treatment with Fenton's reagent and modified Fenton's reagent, and in the biotic control without oxidation. Differences in the highest overall removal efficiencies of 69 % for peat (biotic control) and 59 % for fill (Fenton's reagent) were partially explained by changes in contaminant soil properties upon oxidation. Molecular analysis of 16S rRNA and alkane monooxygenase (alkB) gene abundances indicated that oxidation with Fenton's reagent and modified Fenton's reagent negatively affected microbial abundance. However, regeneration occurred, and final relative alkB abundances were 1-2 orders of magnitude higher in chemically treated microcosms than in the biotic control. 16S rRNA gene fragment fingerprinting with DGGE and prominent band sequencing illuminated microbial community composition and diversity differences between treatments and identified a variety of phylotypes within Alpha-, Beta-, and Gammaproteobacteria. Understanding microbial community dynamics during coupled chemical oxidation and bioremediation is integral to improved biphasic field application. PMID:24092007

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

2014-03-01

195

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

196

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

197

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

198

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

199

Synthesis of electromagnetic functionalized Fe3O4 microspheres/polyaniline composites by two-step oxidative polymerization.  

PubMed

Composites consisting of Fe(3)O(4) microspheres (FMS) and polyaniline (PANI), FMS/PANI, have been successfully prepared through a two-step oxidative polymerization of aniline monomers in the presence of Fe(3)O(4) microspheres. In our two-step polymerization technique, Fe(3+) and ammonium persulfate (APS) are used as the oxidants in each step. It is discovered that the two-step oxidative process plays a dominant role in the morphology of these composites: aniline oligomers oxidized by Fe(3+) are mainly produced in the first stage, and "egg-like" PANI aggregates are obtained in the second stage. It can be found that embedding Fe(3)O(4) microspheres in the polymer matrixes will not only modulate the complex permittivity but also produce magnetic resonance and loss in the composites. Therefore, the characteristic impedance and reflection loss of these composites are greatly improved. Especially, the composite with equal amount of FMS and PANI, FMS/PANI(50), displays very strong reflection loss over a wide frequency range that can be manipulated by the absorber thickness. More importantly, the composites prepared from the two-step chemical oxidative polymerization using hierarchical magnetic materials have better microwave absorption and environmental stability as compared with those composites from Fe(3)O(4) nanoparticles, one-step oxidative polymerization, and physical mixture. We believe the two-step oxidative polymerization technique can be a novel route for the design and preparation of lightweight and highly effective microwave absorbers in the future. PMID:22800337

Cui, Chenkui; Du, Yunchen; Li, Tianhao; Zheng, Xiaoying; Wang, Xiaohong; Han, Xijiang; Xu, Ping

2012-08-01

200

Component analysis of dyads designed for light-driven water oxidation.  

PubMed

A series of seven dyad molecules have been prepared utilizing a [Ru(tpy)(NN)I](+) type oxidation catalyst (NN = 2,5-di(pyrid-2'-yl) pyrazine (1), 2,5-di-(1',8'-dinaphthyrid-2'-yl) pyrazine (2), or 4,6-di-(1',8'-dinaphthyrid-2'-yl) pyrimidine (3). The other bidentate site of the bridging ligand was coordinated with 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), or a substituted derivative. These dinuclear complexes were characterized by their (1)H NMR spectra paying special attention to protons held in the vicinity of the electronegative iodide. In one case, 10a, the complex was also analyzed by single crystal X-ray analysis. The electronic absorption spectra of all the complexes were measured and reported as well as emission properties for the sensitizers. Oxidation and reduction potentials were measured and excited state redox properties were calculated from this data. Turnover numbers, initial rates, and induction periods for oxygen production in the presence of a blue LED light and sodium persulfate as a sacrificial oxidant were measured. Similar experiments were run without irradiation. Dyad performance correlated well with the difference between the excited state reduction potential of the photosensitizer and the ground state oxidation potential of the water oxidation dyad. The most active system was one having 5,6-dibromophen as the auxiliary ligand, and the least active system was the one having 4,4'-dimethylbpy as the auxiliary ligand. PMID:24364791

Kohler, Lars; Kaveevivitchai, Nattawut; Zong, Ruifa; Thummel, Randolph P

2014-01-21

201

Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater.  

PubMed

This work aimed at demonstrating the advantages to use sulfate radical anion for eliminating ciprofloxacin residues from treated domestic wastewater by comparing three UV-254nm based advanced oxidation processes: UV/persulfate (PDS), UV/peroxymonosulfate (PMS) and UV/H2O2. In distilled water, the order of efficiency was UV/PDS>UV/PMS>UV/H2O2 while in wastewater, the most efficient process was UV/PMS followed by UV/PDS and UV/H2O2 mainly because PMS decomposition into sulfate radical anion was activated by bicarbonate ions. CIP was fully degraded in wastewater at pH 7 in 60min for a [PMS]/[CIP] molar ratio of 20. Nine transformation products were identified by liquid chromatography-high resolution-mass spectrometry allowing for the establishment of degradation pathways in the UV/PMS system. Sulfate radical anion attacks prompted transformations at the piperazinyl ring through a one electron oxidation mechanism as a major pathway while hydroxyl radical attacks were mainly responsible for quinolone moiety transformations as a minor pathway. Sulfate radical anion generation has made UV/PMS a kinetically effective process in removing ciprofloxacin from wastewater with the elimination of ciprofloxacin antibacterial activity. PMID:24333713

Mahdi-Ahmed, Moussa; Chiron, Serge

2014-01-30

202

Temporal Stability of Oxidizers: A Preliminary Survey of Aqueous Solutions.  

National Technical Information Service (NTIS)

Aqueous solutions (nominal 0.1N each anion) of various hypochlorite salts (sodium, calcium, lithium) and peroxygen compounds (sodium perborate, sodium persulfate, hydrogen peroxide and magnesium monoperoxyphthalate) have been examined for long-term stabil...

R. E. Pellenbarg

1985-01-01

203

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

PubMed

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 10.7mm(2)/sec, followed by D (9.09mm(2)/sec), C (8.49mm(2)/sec), B(8.28mm(2)/sec) and A(6.48mm(2)/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

2013-08-01

204

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

205

Microbial dechlorination activity during and after chemical oxidant treatment.  

PubMed

Potassium permanganate (PM) and sodium persulfate (PS) are used in soil remediation, however, their compatibility with a coinciding or subsequent biotreatment is poorly understood. In this study, different concentrations of PM (0.005-2g/L) and PS (0.01-4.52 g/L) were applied and their effects on the abundance, activity, and reactivation potential of a dechlorinating enrichment culture were investigated. Expression of the tceA, vcrA and 16S rRNA genes of Dehalococcoides spp. were detected at 0.005-0.01 g/L PM and 0.01-0.02 g/L PS. However, with 0.5-2g/L PM and 1.13-4.52 g/L PS no gene expression was recorded, neither were indicator molecules for total cell activity (Adenosine triphosphate, ATP) detected. Dilution did not promote the reactivation of the microbial cells when the redox potential was above -100 mV. Similarly, inoculated cells did not dechlorinate trichloroethene (TCE) above -100 mV. When the redox potential was decreased to -300 mV and the reactors were bioaugmented for a second time, dechlorination activity recovered, but only in the reactors with 1.13 and 2.26 g/L PS. In conclusion, our results show that chemical oxidants can be combined with a biotreatment at concentrations below 0.5 g/L PM and 1g/L PS. PMID:24096000

Do?an-Suba??, Eylem; Bastiaens, Leen; Boon, Nico; Dejonghe, Winnie

2013-11-15

206

Heat activation/shock temperatures for Bacillus anthracis spores and the issue of spore plate counts versus true numbers of spores.  

PubMed

Assessing true numbers of viable anthrax spores is complex. Optimal heat activation conditions vary with species, media and germinants. Published time/temperature combinations for Bacillus anthracis spores range from 60 degrees C for 1, post-heating counts were less than their pre-heating counterparts on between 71% and 88% of occasions. A high probability was found of viable spore counts differing significantly from counts determined microscopically, with differences of almost 1 log possible. Viable counts were lower than microscopic counts in 15 of 18 tests. PMID:17055602

Turnbull, Peter C B; Frawley, Dody A; Bull, Robert L

2007-02-01

207

Treatment of hydrocarbon contamination under flow through conditions by using magnetite catalyzed chemical oxidation.  

PubMed

Soil pollution by hydrocarbons (aromatic and aliphatic hydrocarbons) is a major environmental issue. Various treatments have been used to remove them from contaminated soils. In our previous studies, the ability of magnetite has been successfully explored to catalyze chemical oxidation for hydrocarbon remediation in batch slurry system. In the present laboratory study, column experiments were performed to evaluate the efficiency of magnetite catalyzed Fenton-like (FL) and activated persulfate (AP) oxidation for hydrocarbon degradation. Flow-through column experiments are intended to provide a better representation of field conditions. Organic extracts isolated from three different soils (an oil-contaminated soil from petrochemical industrial site and two soils polluted by polycyclic aromatic hydrocarbon (PAH) originating from coking plant sites) were spiked on sand. After solvent evaporation, spiked sand was packed in column and was subjected to oxidation using magnetite as catalyst. Oxidant solution was injected at a flow rate of 0.1 mL min(-1) under water-saturated conditions. Organic analyses were performed by GC-mass spectrometry, GC-flame ionization detector, and micro-Fourier transform infrared spectroscopy. Significant abatement of both types of hydrocarbons (60-70 %) was achieved after chemical oxidation (FL and AP) of organic extracts. No significant by-products were formed during oxidation experiment, underscoring the complete degradation of hydrocarbons. No selective degradation was observed for FL with almost similar efficiency towards all hydrocarbons. However, AP showed less reactivity towards higher molecular weight PAHs and aromatic oxygenated compounds. Results of this study demonstrated that magnetite-catalyzed chemical oxidation can effectively degrade both aromatic and aliphatic hydrocarbons (enhanced available contaminants) under flow-through conditions. PMID:22684901

Usman, M; Faure, P; Lorgeoux, C; Ruby, C; Hanna, K

2013-01-01

208

IL-1 beta potentiates heat-activated currents in rat sensory neurons: involvement of IL-1RI, tyrosine kinase, and protein kinase C.  

PubMed

Interleukin 1 beta (IL-1 beta) is a proinflammatory cytokine that maintains thermal hyperalgesia and facilitates the release of calcitonin gene-related peptide from rat cutaneous nociceptors in vivo and in vitro. Brief applications of IL-1 beta to nociceptive neurons yielded a potentiation of heat-activated inward currents (Iheat) and a shift of activation threshold toward lower temperature without altering intracellular calcium levels. The IL-1 beta-induced heat sensitization was not dependent on G-protein-coupled receptors but was mediated by activation of protein kinases. The nonspecific protein kinase inhibitor staurosporine, the specific protein kinase C inhibitor bisindolylmaleimide BIM1, and the protein tyrosine kinase inhibitor genistein reduced the sensitizing effect of IL-1 beta whereas negative controls were ineffective. RT-PCR and in situ hybridization revealed IL-1RI but not RII expression in neurons rather than surrounding satellite cells in rat dorsal root ganglia. IL-1 beta acts on sensory neurons to increase their susceptibility for noxious heat via an IL-1RI/PTK/PKC-dependent mechanism. PMID:12374772

Obreja, Otilia; Rathee, Parvinder K; Lips, Kathrin S; Distler, Carsten; Kress, Michaela

2002-10-01

209

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

210

Oxidative conversion as a means of detecting precursors to perfluoroalkyl acids in urban runoff.  

PubMed

A new method was developed to quantify concentrations of difficult-to-measure and unidentified precursors of perfluoroalkyl carboxylic (PFCA) and sulfonic (PFSA) acids in urban runoff. Samples were exposed to hydroxyl radicals generated by thermolysis of persulfate under basic pH conditions and perfluoroalkyl acid (PFAA) precursors were transformed to PFCAs of related perfluorinated chain length. By comparing PFCA concentrations before and after oxidation, the concentrations of total PFAA precursors were inferred. Analysis of 33 urban runoff samples collected from locations around the San Francisco Bay, CA indicated that PFOS (2.6-26 ng/L), PFOA (2.1-16 ng/L), and PFHxA (0.9-9.7 ng/L) were the predominant perfluorinated compounds detected prior to sample treatment. Following oxidative treatment, the total concentrations of PFCAs with 5-12 membered perfluoroalkyl chains increased by a median of 69%, or between 2.8 and 56 ng/L. Precursors that produced PFHxA and PFPeA upon oxidation were more prevalent in runoff samples than those that produced PFOA, despite lower concentrations of their corresponding perfluorinated acids prior to oxidation. Direct measurements of several common precursors to PFOS and PFOA (e.g., perfluorooctanesulfonamide and 8:2 fluorotelomer sulfonate) accounted for less than 25% of the observed increase in PFOA, which increased by a median value of 37%. Exposure of urban runoff to sunlight, advanced oxidation processes, or microbes could result in modest, but measurable, increases in concentrations of PFCAs and PFSAs. PMID:22900587

Houtz, Erika F; Sedlak, David L

2012-09-01

211

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

212

Sulfate radical-advanced oxidation process (SR-AOP) for simultaneous removal of refractory organic contaminants and ammonia in landfill leachate.  

PubMed

Typically, a mature landfill leachate contains high levels of non-biodegradable organics and ammonia nitrogen. Simultaneous removal of the both persistent leachate pollutants is a significant challenge. This paper reports the first scientific study to apply a sulfate radical (SO(4)(·-)) - based advanced oxidation process (SR-AOP) to treat a mature leachate, with an emphasis of concurrent removal of refractory organics and ammonia. In this study, all the experiments were run in a batch reactor with temperature control. In the thermal persulfate oxidation (TPO) process, persulfate (S(2)O(8)(2-)) was activated by heat to produce powerful oxidants, SO(4)(·-) (E(o) = 2.6 V). Three factors affecting the removal efficiencies of chemical oxygen demand (COD) and ammonia nitrogen were investigated, including initial solution pH (3-8.3), temperature (27-50 °C), and chemical dose (S(2)O(8)(2-):12COD(0) = 0.25-2.0). Typically, acidic pH (3-4), higher temperature, and higher dose favored the removal of COD and ammonia. At S(2)O(8)(2-):12COD(0) = 2 and 50 °C, the COD removal rates were 79% and 91% at pH 8.3 (no pH adjustment) and 4, respectively; and the ammonia nitrogen removal reached 100% at pH 8.3 or 4. SR-AOP appears to be more advantageous over hydroxyl radical (OH?)-based advanced oxidation processes (HR-AOPs) because OH? almost does not oxidize ammonia. Furthermore, compared with Fenton treatment of the same batch leachate sample, the TPO could achieve a higher COD removal at an identical chemical dose. For example, COD removal was 40% at H(2)O(2):2.125COD(0) = 2 during Fenton treatment (pH 3), but 91% at S(2)O(8)(2-):12COD(0) = 2 during TPO (pH 4). These findings demonstrate that SR-AOP is a promising landfill leachate treatment method. PMID:21959093

Deng, Yang; Ezyske, Casey M

2011-11-15

213

Liquid chromatography, chemical oxidation, and online carbon isotope dilution mass spectrometry as a universal quantification system for nonvolatile organic compounds.  

PubMed

A procedure for the universal detection and quantification of polar organic compounds separated by liquid chromatography (LC) based on postcolumn carbon isotope dilution mass spectrometry (IDMS) was developed. The eluent from the LC column is mixed online with a continuous flow of (13)C-enriched sodium bicarbonate, and the sodium persulfate oxidation reaction in acidic media is employed to achieve isotope equilibration. All carbon-containing compounds eluting from the column are oxidized to (12)CO(2) and (13)CO(2), respectively, and the carbon dioxide is separated from the aqueous phase using a gas-permeable membrane. The gaseous carbon dioxide is then carried to the mass spectrometer for isotope ratio measurements. Different water-soluble organic compounds were evaluated using a flow injection configuration to assess the efficiency of the oxidation process. Most water-soluble organic compounds tested showed quantitative oxidation. However, chemical structures involving conjugated C?N double bounds and guanidinium-like structures were found to be resistant to the oxidation and were further studied. For this purpose, (13)C(1)-labeled creatine (with the isotopic label in the guanidinium group) was employed as model compound. Specific conditions for the quantitative oxidation of these compounds required lower flow rates and the addition of metallic catalysts. This novel approach was tested as a universal detection and quantification system for LC. A simple standard mixture of four amino acids was separated under 100% aqueous conditions and quantified without the need for specific standards with good accuracy and precision using potassium hydrogen phthalate as internal standard. The main field of application of the developed method is for the purity assessment of organic standards with direct traceability to the International System of Units (SI). PMID:23252800

Díaz, Sergio Cueto; Encinar, Jorge Ruiz; Sanz-Medel, Alfredo; Alonso, J Ignacio García

2013-02-01

214

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.

215

Enabling light-driven water oxidation via a low-energy RuIV=O intermediate.  

PubMed

The discovery of catalysts capable of driving water oxidation at relatively low overpotential is a key challenge for efficient photoinduced water oxidation. The mononuclear Ru(II) polypyridyl complex (1) [Ru(NPM)(H2O)(pic)2](2+) (NPM = 4-tert-butyl-2,6-di-(1',8'-naphthyrid-2'-yl)-pyridine, pic = 4-picoline) has been examined as a catalyst for visible-light-driven water oxidation in a three-component homogeneous system containing [Ru(bpy)3](2+) as a photosensitizer, persulfate as a sacrificial electron acceptor and catalyst 1. In contrast to the well-established water oxidation mechanism via the nucleophilic attack of a water molecule on the high-energy [Ru(V)=O](3+) species, a lower-energy "direct pathway" for O-O bond formation via a [Ru(IV)=O](2+) intermediate was proposed for the first time for the catalyst 1 (Polyansky et al., J. Am. Chem. Soc., 2011, 133, 14649). In this report we successfully demonstrate that this unique proton-coupled low-energy pathway actually takes place with the use of a mild oxidant such as the photogenerated [Ru(bpy)3](3+) (1.26 V vs. NHE) to drive water oxidation. The overall quantum yield of 9%, TOF of 0.12 s(-1) and TON of 103 (limited solely by a drop in pH) were found for photochemical water oxidation with 1 using [Ru(bpy)3](2+) as a photosensitizer and [S2O8](2-) as a sacrificial electron acceptor. These values render catalyst 1 as one of the most active mononuclear ruthenium-based catalysts for light-driven water oxidation in a homogeneous system. The utilization of a pH-dependent pathway for water oxidation is a new and promising direction as a low-energy pathway. Furthermore, the detailed analysis of individual photochemical steps leading to O2 evolution provides benchmarks for future mechanistic studies of photo-induced water oxidation catalysis. PMID:23860663

Lewandowska-Andralojc, Anna; Polyansky, Dmitry E; Zong, Ruifa; Thummel, Randolph P; Fujita, Etsuko

2013-09-01

216

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

217

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

218

Oxidant signals and oxidative stress  

Microsoft Academic Search

Although oxidants clearly possess the capacity to behave in a random and destructive fashion, growing evidence suggests that in many instances the production of reactive oxygen species is tightly regulated and their downstream targets exquisitely specific. This past year, several notable advances have been made in defining the specific redox-dependent targets of intracellular oxidants, as well as the myriad pathways

Toren Finkel

2003-01-01

219

Spectrophotometric detection of iodide and chromic (III) in urine after oxidation to iodine and chromate (VI).  

PubMed

Tests for oxidizing adulterants in urine are a continuing challenge to the drug-testing program. Iodine was found to destroy morphine and 6-acetylmorphine almost immediately. The effects were less evident on 11 -nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). When the urine solution was tested for iodine by a chromogenic substrate, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), no iodine was detected. Masking drug and adulterant simultaneously made iodine a preferred oxidizing adulterant for drug abusers. In this study, the reduced iodide was oxidized by sodium nitrite to iodine. The excess nitrite was decomposed by sulfamic acid and the iodine was detected by ABTS. Linearity was 12.7 to 635 mg/L (0.1 to 5 mmol/L, y = 0.9966x + 0.0016, R2 = 1.0000). Precisions (coefficient of variation) were within +/- 4.1% and quantitative accuracies were within 97% of expected values (n=5). Chromate, iodate, periodate, and persulfate interfered with the method. To alleviate the problem, the positive specimens were tested again by an iodine-specific method. After oxidation, the samples were treated with sodium azide and ammonium thiocyanate. In presence of thiocyanate, the azide reduced iodine to iodide almost immediately, and the solutions showed negative response to ABTS. The results were compared with that of a control group tested without thiocyanate. When iodine was present, the ratios of thiocyanate to control were less than 6%. Chromate was also found to destroy THC-acid in urine, and during storage most of the chromate changed to chromic (III). In this study, chromic was oxidized to chromate by hydrogen peroxide and sodium hydroxide and detected by 1,5-diphenylcarbazide. Linearity was 5.2 to 156 mg/L (0.1 to 3.0 mmol/L, y = 1.0285x - 0.0034, R2 = 0.9998). Precisions were within +/- 8.5% and quantitative accuracies were within 92% of expected values (n=5). The test was not interfered by other oxidizing agents. Both iodide and chromic oxidation methods showed urine backgrounds less than 1.27 and 0.52 mg/L, respectively (< 0.01 mmol/L). It indicated that a response more than 10 times of the background could be considered as oxidant contamination or adulteration of urine specimens. PMID:16419396

Paul, Buddha D; Jacobs, Aaron

2005-10-01

220

Cadmium Oxide.  

National Technical Information Service (NTIS)

These data sheets present a compilation of a wide range of electronic properties for cadmium oxide. Electrical properties include conductivity, dielectric constant, Hall coefficient, and mobility. Emission data have been broken down into the varied electr...

M. Neuberger

1966-01-01

221

Chemical Conversion of PON to Nitrous Oxide for Nitrogen Isotopic Analysis : High- Sensitivity Tracer Assay for Nitrogen Fixation  

NASA Astrophysics Data System (ADS)

We present a method for high-sensitivity nitrogen isotopic analysis of particulate organic nitrogen (PON) in seawater and freshwater, for the aim of measuring the rate of nitrogen fixation through 15N2 tracer technique for samples that contain low numeric abundance of organisms. The method composed of the traditional oxidation/reduction methods: such as oxidation of PON to nitrate using persulfate, the reduction of nitrate to nitrite using spongy cadmium, and further reduction of nitrite to nitrous oxide using sodium azide in an acetic acid buffer. Then, Nitrous oxide is purged from the water and trapped cryogenically with subsequent release into a gas chromatography column to analyze stable nitrogen isotopic compositions using a continuous-flow isotope ratio mass spectrometer. A standard deviation less than 0.3 ‰ for nitrogen was found for PON samples containing more than 80 nmolN, with a blank nitrogen of 20 nmolN. Nitrogen isotopic fractionation were consistent within each batch of analysis. Besides, we found that we can also determine nitrogen isotopic compositions of total dissolved nitrogen (TDN, sum of NO3-, NO2-, ammonium, and DON), by applying the method for filtrate samples. Our method may prove to obtain isotopic information for lower quantities of PON and TDN than other methods, so that we can reduce quantities of water samples needed for incubation to determine the nitrogen fixation rate in both seawater and freshwater. Besides, the method is also useful to determine the rate of nitrogen fixation by the small size fraction in ocean. We will also present the results obtained at western subtropical North Pacific to support our conclusions.

Tsunogai, U.; Kido, T.; Hirota, A.; Ohkubo, S.; Komatsu, D. D.; Nakagawa, F.

2006-12-01

222

Fabrication of polypyrrole-coated carbon nanotubes using oxidant-surfactant nanocrystals for supercapacitor electrodes with high mass loading and enhanced performance.  

PubMed

A conceptually new approach to the fabrication of polypyrrole (PPy)-coated multiwalled carbon nanotubes (MWCNT) for application in electrodes of electrochemical supercapacitors (ES) is proposed. Cetrimonium persulfate (CTA)2S2O8 in the form of nanocrystals is used as an oxidant for the chemical polymerization of PPy. Ponceau S (PS) dye is investigated as a new anionic dopant. Testing results show that PS allows reduced PPy particle size and improved electrochemical performance, whereas (CTA)2S2O8 nanocrystals promote the formation of PPy nanofibers. We demonstrate for the first time that MWCNT can be efficiently dispersed using (CTA)2S2O8 nanocrystals. The analysis of the dispersion mechanism indicates that (CTA)2S2O8 dissociation is catalyzed by MWCNT. This new finding opens a new and promising strategy in MWCNT dispersion for colloidal processing of nanomaterials and electrophoretic nanotechnology. Uniformly coated MWCNT are obtained using (CTA)2S2O8 as a dispersant for MWCNT and oxidant for PPy polymerization and utilizing advantages of PS as an efficient dopant and nanostructure controlling agent. The analysis of the testing results provides an insight into the influence of PS molecular structure on PPy nanostructure and electrochemical properties. The PPy-coated MWCNT show superior electrochemical performance compared to PPy nanoparticles. The proof-of-principle is demonstrated by the fabrication of ES electrodes with excellent electrochemical performance at high active material loadings, good capacitance retention at high charge-discharge rates, and excellent cycling stability. PMID:24255939

Shi, Kaiyuan; Zhitomirsky, Igor

2013-12-26

223

[Oxidative stress].  

PubMed

Oxidative stress is defined as an imbalance between the production of reactive oxygen species (ROS) and the antioxidant network, in favour of the former. Our lifestyle (smoking, alcoholism, obesity, intense physical exercise), but also our inadequate diet, contributes to significantly increase the production of ROS in our organism. This is potentially associated with an increased risk of developing ageing-related pathologies such as cardiovascular diseases and cancer. As a matter of prevention, it is necessary to have in hands a high technology allowing to correctly evidence the oxidative stress status of an individual in order to render optimal our antioxidant defences and to decrease the oxidative damages in DNA, proteins and lipids. PMID:18069575

Haleng, J; Pincemail, J; Defraigne, J O; Charlier, C; Chapelle, J P

2007-10-01

224

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) [Cambridge, MA; Lahr, David L. (Cambridge, MA) [Cambridge, MA

2010-11-09

225

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...

226

Degradation of 2,4-dinitrophenol using a combination of hydrodynamic cavitation, chemical and advanced oxidation processes.  

PubMed

In the present work, degradation of 2,4-dinitrophenol (DNP), a persistent organic contaminant with high toxicity and very low biodegradability has been investigated using combination of hydrodynamic cavitation (HC) and chemical/advanced oxidation. The cavitating conditions have been generated using orifice plate as a cavitating device. Initially, the optimization of basic operating parameters have been done by performing experiments over varying inlet pressure (over the range of 3-6 bar), temperature (30 °C, 35 °C and 40 °C) and solution pH (over the range of 3-11). Subsequently, combined treatment strategies have been investigated for process intensification of the degradation process. The effect of HC combined with chemical oxidation processes such as hydrogen peroxide (HC/H2O2), ferrous activated persulfate (HC/Na2S2O8/FeSO4) and HC coupled with advanced oxidation processes such as conventional Fenton (HC/FeSO4/H2O2), advanced Fenton (HC/Fe/H2O2) and Fenton-like process (HC/CuO/H2O2) on the extent of degradation of DNP have also been investigated at optimized conditions of pH 4, temperature of 35 °C and inlet pressure of 4 bar. Kinetic study revealed that degradation of DNP fitted first order kinetics for all the approaches under investigation. Complete degradation with maximum rate of DNP degradation has been observed for the combined HC/Fenton process. The energy consumption analysis for hydrodynamic cavitation based process has been done on the basis of cavitational yield. Degradation intermediates have also been identified and quantified in the current work. The synergistic index calculated for all the combined processes indicates HC/Fenton process is more feasible than the combination of HC with other Fenton like processes. PMID:23538121

Bagal, Manisha V; Gogate, Parag R

2013-09-01

227

A Ru-Co hybrid material based on a molecular photosensitizer and a heterogeneous catalyst for light-driven water oxidation.  

PubMed

A novel approach to anchor a molecular photosensitizer onto a heterogeneous water oxidation catalyst via coordination bonds is presented. A photosensitizer (1) based on [Ru(bpy)3](2+) and decorated with two methylenediphosphonate (M2P) groups has been designed and synthesized for this purpose. The M2P groups in complex 1 allow for coordination of cobalt ions to afford a novel molecular-heterogeneous hybrid material P1. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize P1 as an amorphous, non-uniform material that contains Ru and Co in a ratio of 1?:?2. A suspension of P1 in a buffered aqueous solution is active as a light-driven water oxidation catalyst in the presence of persulfate (S2O8(2-)) as electron acceptor. The yield of oxygen is higher when P1 is prepared in situ by mixing and illuminating 1 and Co(2+) in the presence of S2O8(2-). After oxygen evolution ceases, a second material P2 can be isolated from the reaction mixture. P2 is characterized by a lower Ru content than P1, and contains Co in a higher oxidation state. Interestingly, P2 as a freshly prepared suspension is also active for light-driven water oxidation. It is shown that 1 resides in the interior of P1 and P2, and is thus in a location where undesirable quenching pathways of the photo-excited state of 1 limit the oxygen production yields for both P1 and P2. PMID:24419175

Wang, Hong-Yan; Liu, Jia; Zhu, Jiefang; Styring, Stenbjörn; Ott, Sascha; Thapper, Anders

2014-02-28

228

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

2014-05-28

229

Effects of oxidizing adulterants on detection of 11-nor-delta9-THC-9-carboxylic acid in urine.  

PubMed

Bleach, nitrite, chromate, and hydrogen peroxide-peroxidase are effective urine adulterants used by the illicit drug users to conceal marijuana-positive results. Methods for detecting nitrite and chromate are available. Effects of other oxidizing agents that could possibly be used as adulterants and are difficult to detect or measure are presented in this report. Urine samples containing 40 ng/mL of 11-nor-delta9-THC-9-carboxylic acid (THC-acid) were treated with 10 mmol/L of commonly available oxidizing agents. Effects of horseradish peroxidase of activity 10 unit/mL and extracts from 2.5 g of red radish (Raphanus sativus, Radicula group), horseradish (Armoracia rusticana), Japanese radish (Raphanus sativus, Daikon group), and black mustard seeds (Brassica nigra), all with 10 mmol/L of hydrogen peroxide, were also examined. After 5 min, 16 h and 48 h of exposure at room temperature (23 degrees C) the specimens were tested by a gas chromatographic-mass spectrometric method for THC-acid. A control group treated with sodium hydrosulfite to reduce the oxidants, was also tested to investigate the effect of oxidizing agents on THC-acid in the extraction method. THC-acid was lost completely in the extraction method when treated with chromate, nitrite, oxone, and hydrogen peroxide/ferrous ammonium sulfate (Fenton's reagent). Some losses were also observed with persulfate and periodate (up to 25%). These oxidants, and other oxidizing agents like permanganate, periodate, peroxidase, and extracts from red radish, horseradish, Japanese radish and black mustard seeds destroyed most of the THC-acid (> 94%) within 48 h of exposure. Chlorate, perchlorate, iodate, and oxychloride under these conditions showed little or no effect. Complete loss was observed when THC-acid was exposed to 50 mmol/L of oxychloride for 48 h. Several oxidizing adulterants that are difficult to test by the present urine adulterant testing methods showed considerable effects on the destruction of THC-acid. The time and temperature for these effects were similar to those used by most laboratories to collect and test specimens. In several cases, the loss of THC-acid was > 94%. PMID:12423000

Paul, Buddha D; Jacobs, Aaron

2002-10-01

230

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

231

Persulfates from China. Investigation No. 731-TA-749 (Final).  

National Technical Information Service (NTIS)

The Commission instituted this investigation effective July 11, 1996, following receipt of a petition filed with the Commission and the Department of Commerce by FMC Corporation, Chicago, IL. The final phase of the investigation was scheduled by the Commi...

1997-01-01

232

Persulfates from China. Investigation No. 731-TA-749 (Preliminary).  

National Technical Information Service (NTIS)

On the basis of the record developed in the subject investigations, the Commission determines, pursuant to section 733(b) of the Tariff Act of 1930 (19 U.S.C. section 1673(b)), that is reasonable indication that an industry United States is threatened wit...

1996-01-01

233

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

234

PREFACE: Semiconducting oxides Semiconducting oxides  

NASA Astrophysics Data System (ADS)

Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for their help in producing this special section. We hope that it conveys some of the excitement and significance of the field. Semiconducting oxides contents Chemical bonding in copper-based transparent conducting oxides: CuMO2 (M = In, Ga, Sc) K G Godinho, B J Morgan, J P Allen, D O Scanlon and G W Watson Electrical properties of (Ba, Sr)TiO3 thin films with Pt and ITO electrodes: dielectric and rectifying behaviourShunyi Li, Cosmina Ghinea, Thorsten J M Bayer, Markus Motzko, Robert Schafranek and Andreas Klein Orientation dependent ionization potential of In2O3: a natural source for inhomogeneous barrier formation at electrode interfaces in organic electronicsMareike V Hohmann, Péter Ágoston, André Wachau, Thorsten J M Bayer, Joachim Brötz, Karsten Albe and Andreas Klein Cathodoluminescence studies of electron irradiation effects in n-type ZnOCasey Schwarz, Yuqing Lin, Max Shathkin, Elena Flitsiyan and Leonid Chernyak Resonant Raman scattering in ZnO:Mn and ZnO:Mn:Al thin films grown by RF sputteringM F Cerqueira, M I Vasilevskiy, F Oliveira, A G Rolo, T Viseu, J Ayres de Campos, E Alves and R Correia Structure and electrical properties of nanoparticulate tungsten oxide prepared by microwave plasma synthesisM Sagmeister, M Postl, U Brossmann, E J W List, A Klug, I Letofsky-Papst, D V Szabó and R Würschum Charge compensation in trivalent cation doped bulk rutile TiO2Anna Iwaszuk and Michael Nolan Deep level transient spectroscopy studies of n-type ZnO single crystals grown by different techniquesL Scheffler, Vl Kolkovsky, E V Lavrov and J Weber Microstructural and conductivity changes induced by annealing of ZnO:B thin films deposited by chemical vapour depositionC David, T Girardeau, F Paumier, D Eyidi, B Lacroix, N Papathanasiou, B P Tinkham, P Guérin and M Marteau Multi-component transparent conducting oxides: progress in materials modellingAron Walsh, Juarez L F Da Silva and Su-Huai Wei Thickness dependence of the strain, band gap and transport properties of epitaxial In2O3 thin films grown on Y-stabilised ZrO2(111) K H L Zhang, V K Lazarov, T D Veal, F

Catlow, Richard; Walsh, Aron

2011-08-01

235

Nitric oxide therapies  

US Patent & Trademark Office Database

A method for delivering nitric oxide therapy to a subject can include administering a composition including a nitric-oxide releasing agent and silica to the subject and releasing a therapeutic amount of nitric oxide from the composition.

2013-12-24

236

Characterization of Biodiesel Oxidation and Oxidation Products.  

National Technical Information Service (NTIS)

A literature survey on the characterization of biodiesel oxidation and oxidation products was Task 1 of this project. The survey identified two areas in which there was a deficiency of technical understanding: (1) The relationship between a biodiesels ten...

J. A. Waynick

2007-01-01

237

Indium oxide, tin oxide and indium tin oxide nanostructure growth by vapor deposition  

Microsoft Academic Search

Indium oxide, tin oxide and indium tin oxide nanowires have been grown by vapor deposition on Si and quartz substrates. Under the growth conditions used, pure SiOx nanowires, a mixture of SiOx and indium oxide, tin oxide or indium tin oxide nanostructures, or pure indium oxide, tin oxide or indium tin oxide nanostructures could be obtained at different substrate temperatures.

M. K. Fung; K. K. Wong; X. Y. Chen; Y. F. Chan; A. M. C. Ng; A. B. Djuriši?; W. K. Chan

238

Investigation of Heat-Activated Cushioning Material.  

National Technical Information Service (NTIS)

A study was initiated to determine the feasibility of obtaining a solid urethane system which could be foamed-in-place, by the application of heat, in order to provide a cushioning material for ship-to-shore transfers. The best formulation obtained contai...

D. Minuti

1967-01-01

239

The effect of synthesis conditions on the properties of polyaniline film  

Microsoft Academic Search

The effect of oxidant (ammonia persulfate)\\/aniline ratio (APS\\/An) and reaction temperature on the yield, oxidation state, solubility in NMP and the properties of the films made from NMP solution were studied.

S. M. Yang; J. T. Chen

1995-01-01

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

Photo-oxidation catalysts  

DOEpatents

Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

Pitts, J. Roland (Lakewood, CO); Liu, Ping (Irvine, CA); Smith, R. Davis (Golden, CO)

2009-07-14

242

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.

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

243

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

244

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.

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

2010-01-01

245

Electrolytic oxidation of anthracite  

USGS Publications Warehouse

An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

Senftle, F. E.; Patton, K. M.; Heard, Jr. , I.

1981-01-01

246

Mercuric oxide poisoning  

MedlinePLUS

Mercuric oxide is a form of mercury. It is a type of mercury salt. There are different types of ... poisonings . This article discusses poisoning from swallowing mercuric oxide. This is for information only and not for ...

247

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

248

Oxidative stress in mitochondria  

Microsoft Academic Search

In mitochondria, oxidative phosphorylation and enzymatic oxidation of biogenic amines by monoamine oxidase produce reactive\\u000a oxygen and nitrogen species, which are proposed to cause neuronal cell death in neurodegenerative disorders, including Parkinson’s\\u000a and Alzheimer’s disease. In these disorders, mitochondrial dysfunction, increased oxidative stress, and accumulation of oxidation-modified\\u000a proteins are involved in cell death in definite neurons. The interactions among these

Makoto Naoi; Wakako Maruyama; Masayo Shamoto-Nagai; Hong Yi; Yukihiro Akao; Masashi Tanaka

2005-01-01

249

Nanobelts of Semiconducting Oxides  

Microsoft Academic Search

Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cad- mium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section

H. Iikura; S. Mori; M. Sawamura; E. Nakamura; Zheng Wei Pan; Zu Rong Dai; Zhong Lin Wang

2001-01-01

250

Oxidation in rheumatoid arthritis  

Microsoft Academic Search

Oxygen metabolism has an important role in the pathogenesis of rheumatoid arthritis. Reactive oxygen species (ROS) produced in the course of cellular oxidative phosphorylation, and by activated phagocytic cells during oxidative bursts, exceed the physiological buffering capacity and result in oxidative stress. The excessive production of ROS can damage protein, lipids, nucleic acids, and matrix components. They also serve as

Carol A Hitchon; Hani S El-Gabalawy

2004-01-01

251

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

252

Oxide anodes in electro-organic oxidation. Oxidation of maleic addon tungsten oxide anodes  

Microsoft Academic Search

The electrochemical oxidation of maleic acid on tungsten anodes has been investigated. Glyoxal and carbon dioxide were the main products together with tartaric acid and acetaldehyde. Glyoxal is also obtained as the main product from the oxidation ofd-tartaric acid. Under the same conditions succinic acid is completely oxidized to carbon dioxide and water. The anodic dissolution of tungsten and the

G. Filardo; F. Di Quarto; S. Gambino; G. Silvestri

1982-01-01

253

Oxidation of aluminum nanoclusters  

SciTech Connect

The dynamics of oxidation of aluminum nanoclusters (20 nm diameter) is investigated using a parallel molecular dynamics approach based on variable charge interatomic interactions due to Streitz and Mintmire that include both ionic and covalent effects. Simulations are performed for both canonical ensembles for molecular oxygen (O{sub 2}) environments and microcanonical ensembles for molecular (O{sub 2}) and atomic (O{sub 1}) oxygen environments. Structural and dynamic correlations in the oxide region are calculated, as well as the evolution of charges, surface oxide thickness, diffusivities of atoms, and local stresses. In the microcanonical ensemble, the oxidizing reaction becomes explosive in both molecular and atomic oxygen environments due to the enormous energy release associated with Al-O bonding. Local stresses in the oxide scale cause rapid diffusion of aluminum and oxygen atoms. Analyses of the oxide scale reveal significant charge transfer and a variation of local structures from the metal-oxide interface to the oxide-environment interface. In the canonical ensemble, oxide depth grows linearly in time until {approx}30 ps, followed by saturation of oxide depth as a function of time. An amorphous oxide layer of thickness {approx}40 A is formed after 466 ps, in good agreement with experiments. The average mass density in the oxide scale is 75% of the bulk alumina density. Evolution of structural correlation in the oxide is analyzed through radial distribution and bond angles. Through detailed analyses of the trajectories of O atoms and their formation of OAl{sub n} structures, we propose a three-step process of oxidative percolation that explains deceleration of oxide growth in the canonical ensemble.

Campbell, Timothy J. [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Mississippi State University, Stennis Space Center, Mississippi 39529 (United States); Aral, Gurcan; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Ogata, Shuji [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2005-05-15

254

A Microscale Oxidation Puzzle  

NASA Astrophysics Data System (ADS)

We have adapted oxidation of an alcohol with sodium hypochlorite solution to a "puzzle" approach by using a diol as the substrate for oxidation. The diols under investigation have both a primary and a secondary hydroxyl group. There are three possible outcomes to the reaction: (i) only the primary alcohol is oxidized to the aldehyde (or carboxylic acid); (ii) only the secondary alcohol is oxidized to the ketone; or (iii) both alcohols are oxidized. The assignment is to perform the reaction and determine the structure of the product through interpretation of the IR spectrum. Examples using two commercially available diols are shown.

Pelter, Michael W.; Macudzinski, Rebecca M.; Passarelli, Mary Ellen

2000-11-01

255

Oxidative DNA modifications.  

PubMed

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 lesions in oxidative DNA repair knock-out animals; defective repair of oxidative lesions in cancer-prone progeria syndromes; reduced cancer incidence in populations with high dietary antioxidant intake; and increased oxidative stress to DNA in tobacco smokers. Conflicting evidence for a relation between oxidative stress to DNA and cancer is: disagreement about the true levels and occurrence of the oxidative lesions in vivo; failure to identify the localization of oxidative lesions in important genes, e.g. tumor suppressor and oncogenes; lack of evidence that the oxidative lesions induce mutations in vivo; no cancer development in animals knocked-out for specific DNA repair enzymes in spite of high tissue levels of oxidative lesions; and unchanged cancer rates after antioxidant interventions in large clinical controlled and randomized trials. The rate of DNA oxidation has been estimated from urinary excretion of repair products and it is evident that if these lesions were not repaired, a large part of DNA would be oxidized to a degree not compatible with living. The methodologies by which oxidative DNA modifications are measured cover a wide and different range, advantages and disadvantages will be presented. One particular problem is artificial oxidation, and methods to prevent such artifacts will be presented together with results from a large interlaboratory standardization program. The methodology by which the lesions can be measured is complicated and prone to artifacts during DNA isolation, digestion, derivatization and maybe even during the separation procedure proper prior to detection. A large effort from 20+ laboratories supported by a grant from the EU has reduced artifacts considerably and work towards interlaboratory standardization of the methodology is in progress. The presently agreed "normal" levels of the most frequent known lesion 8-oxodG is about 5 per million dG's in DNA. A comprehensive evaluation of the evidence, from chemistry to clinical and epidemiological trials, linking oxidative modifications to cancer will be given. Finally, an estimate of the quantitative role oxidative DNA modifications play among the multiplicity of other insults is given. While there is no question that all of these oxidative mechanisms do exist, quantitative data on their importance for the human situation do not exist. Prospective human studies that can provide such quantitative data on different mechanisms are underway. PMID:16092724

Poulsen, Henrik E

2005-07-01

256

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

257

Oxidation Resistance of Silicon Ceramics.  

National Technical Information Service (NTIS)

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 grap...

H. Yasutoshi K. Hirota

1984-01-01

258

Preparation of Monocrystalline Cuprous Oxide  

Microsoft Academic Search

A method is described for preparing large single crystals of cuprous oxide by oxidation of monocrystalline copper. The initial oxidation is performed slowly at low oxygen pressure and temperature, to promote oriented growth of the oxide film. The cuprous oxide crystals obtained from the oxidation process showed subgrain boundaries which were removed by subsequent annealing.

Yukiko Ebisuzaki

1961-01-01

259

Selective methane oxidation over promoted oxide catalysts.  

National Technical Information Service (NTIS)

Principal accomplishments have been achieved in all three areas of selective catalytic oxidation of methane that have been pursued in this research project. These accomplishments are centered on the development of catalyst systems that produce high space ...

K. Klier R. G. Herman

1995-01-01

260

Selective methane oxidation over promoted oxide catalysts.  

National Technical Information Service (NTIS)

Objective was to selectively oxidize methane to C(sub 2) hydrocarbons and to oxygenates, in particular formaldehyde and methanol, in high space time yields under relatively mild reaction conditions. Results in this document are reported under the headings...

K. Klier R. G. Herman

1993-01-01

261

ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION  

SciTech Connect

Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide fi lm to fl ake off. Further studies are needed to defi ne the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

Dang, Y. Y.; Bhuiyan, M.S.; Paranthaman, M. P.

2008-01-01

262

Mechanism of N(5)-ethyl-flavinium cation formation upon electrochemical oxidation of N(5)-ethyl-4a-hydroxyflavin pseudobase.  

PubMed

We investigated the oxidation behavior of 5-ethyl-4a-hydroxy-3-methyl-4a,5-dihydrolumiflavin (pseudobase Et-FlOH) in acetonitrile with the aim of determining if the two-electron oxidized Et-FlOH(2+) undergoes a release of hydroxyl cation and the production of 5-ethyl-3methyllumiflavinium cation (Et-Fl(+)). The focus of this work is to investigate the possibility of using Et-FlOH as a catalyst for water oxidation. The cyclic voltammetry demonstrates that Et-FlOH exhibits two one-electron oxidation potentials at +0.95 and +1.4 V versus normal hydrogen electrode (NHE), with the second oxidation potential being irreversible. The production of Et-Fl(+) is observed in the cyclic voltammetry of Et-FlOH and has been previously assigned to the release of OH(+) from the two-electron oxidized Et-FlOH(2+). The results of our study show that this is not the case: (i) we performed bulk electrolysis of the electrolyte solution at +2 V and then added Et-FlOH to the electrolyzed solution. We found that Et-Fl(+) is produced from this solution, even though Et-FlOH itself was not oxidized; (ii) reactions of Et-FlOH with chemical oxidants (ceric ammonium nitrate, nitrosyl tetrafluoroborate, and tetrabutylammonium persulfate) demonstrate that Et-Fl(+) production occurs only in the presence of strong Lewis acids, such as Ce(4+) and NO(+) ions. On the basis of these results, we propose that the production of Et-Fl(+) in the electrochemistry of Et-FlOH occurs because of the shift in the Et-FlOH/Et-Fl(+) acid-base equilibrium in the presence of protons released during anodic oxidation. We identified two sources of protons: (i) oxidation of traces of water present in the acetonitrile releases oxygen and protons and (ii) two-electron oxidized Et-FlOH(2+) releases protons located on the N(5)-alkyl chain. The release of protons from Et-FlOH(2+) was confirmed by cyclic voltammetry of Et-FlOH in the presence of pyridine as a base. The first oxidation peak of Et-FlOH at +0.95 V is reversible in the absence of pyridine. The addition of pyridine leads to the shift of the oxidation potential to a less positive value, which is consistent with a proton-coupled electron transfer (PCET). Furthermore, the anodic current increases, and the cathodic peak becomes irreversible, giving rise to two additional reduction peaks at -0.2 and -1 V. The same reduction peaks were observed in the high scan rate cyclic voltammogram of Et-FlOH in the absence of pyridine, implying that the release of protons indeed occurs from Et-FlOH(2+). To determine which functional group of Et-FlOH(.+) is the source of protons, we performed DFT calculations at the B3LYP/6-311++G** level of theory for a reaction of Et-FlOH(.+) with pyridine and identified two proton sources: (i) the >N-CH(2)- group of the N(5) alkyl chain and (ii) the -OH group in the 4a-position of the radical cation. Because the appearance of new reduction peaks at -0.2 and -1.0 V occurs in the model compound that lacks -OH protons (Et-FlOMe), we conclude that the proton removal occurs predominantly from the >N-CH(2)- moiety. PMID:20597524

Sichula, Vincent; Hu, Ying; Mirzakulova, Ekaterina; Manzer, Samuel F; Vyas, Shubham; Hadad, Christopher M; Glusac, Ksenija D

2010-07-29

263

Periodontal treatment decreases plasma oxidized LDL level and oxidative stress  

Microsoft Academic Search

Periodontitis induces excessive production of reactive oxygen species in periodontal lesions. This may impair circulating\\u000a pro-oxidant\\/anti-oxidant balance and induce the oxidation of low-density lipoprotein (LDL) in blood. The purpose of this study\\u000a was to monitor circulating oxidized LDL and oxidative stress in subjects with chronic periodontitis following non-surgical\\u000a periodontal treatment. Plasma levels of oxidized LDL and oxidative stress in 22

Naofumi Tamaki; Takaaki Tomofuji; Daisuke Ekuni; Reiko Yamanaka; Manabu Morita

264

Design for Oxidation Resistance  

NASA Technical Reports Server (NTRS)

Alloys intended for use in high-temperature environment rely on the formation of a continuous, compact, slow-growing oxide layer for oxidation and hot corrosion resistance. To be protective, this oxide layer must be chemically, thermodynamically stable. Successful alloy design for oxidative environment is best achieved by developing alloys that are capable of forming adherent scales of either alumina (Al2O3), chromia (Cr2O3), or silica (SiO2). In this article, emphasis has been placed on the issue related to high-temperature oxidation of superalloys used in gas turbine engine application. Despite the complexity of these alloys, optimal performance has been associated with protective alumina scale formation. As will be described below, both compositional makeup and protective coatings play key role in providing oxidation protection. Other high-temperature materials described include nickel and titanium aluminide intermetallics, refractory metal, and ceramics.

Smialek, James L.; Schaeffer, Jon C.; Barrett, Charles A.

1997-01-01

265

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

266

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.

Sherman, David M.; Bristol, University O.

267

Multifunctional Oxide Heterostructures  

SciTech Connect

This book is devoted to the rapidly developing field of oxide thin-films and heterostructures. Oxide materials combined with atomic-scale precision in a heterostructure exhibit an abundance of macroscopic physical properties involving the strong coupling between the electronic, spin, and structural degrees of freedom, and the interplay between magnetism, ferroelectricity, and conductivity. Recent advances in thin-film deposition and characterization techniques made possible the experimental realization of such oxide heterostructures, promising novel functionalities and device concepts.

Tsymbal, E Y [University of Nebraska, Lincoln; Dagotto, Elbio R [ORNL; Eom, Professor Chang-Beom [University of Wisconsin, Madison; Ramesh, Ramamoorthy [University of California, Berkeley

2012-01-01

268

REVERSIBLE SOLID OXIDE CELLS  

Microsoft Academic Search

ABSTRACT The reversibility of solid oxide fuel cells (SOFC), i.e. that they could also work in the solid oxide electrolyser cell (SOEC) mode, was proven already 25 years ago by A.O. Isenberg 1 . Electrolysis of both water (steam) and CO2was demonstrated. Recently, the increasing interest in hydrogen,production has created further interest in the solid oxide cells (SOC) as electrolyser.

Mogens Mogensen; Søren Højgaard Jensen; Anne Hauch; Ib Chorkendorff; Torben Jacobsen

269

40 CFR 268.45 - Treatment standards for hazardous debris.  

Code of Federal Regulations, 2013 CFR

...2) chlorine; (3) chlorine dioxide; (4) ozone or UV (ultraviolet light) assisted ozone; (5) peroxides; (6) persulfates; (7) perchlorates; (8) permanganates; and/or (9) other oxidizing reagents of equivalent destruction...

2013-07-01

270

40 CFR 268.42 - Treatment standards expressed as specified technologies.  

Code of Federal Regulations, 2013 CFR

...2) chlorine; (3) chlorine dioxide; (4) ozone or UV (ultraviolet light) assisted ozone; (5) peroxides; (6) persulfates; (7) perchlorates; (8) permangantes; and/or (9) other oxidizing reagents of equivalent efficiency,...

2013-07-01

271

Thin zinc oxide and cuprous oxide films for photovoltaic applications  

Microsoft Academic Search

Metal oxide semiconductors and heterojunctions made from thin films of metal oxide semiconductors have broad range of functional properties and high potential in optical, electrical and magnetic devices such as light emitting diodes, spintronic devices and solar cells. Among the oxide semiconductors, zinc oxide (ZnO) and cuprous oxide (Cu2O) are attractive because they are inexpensive, abundant and nontoxic. As synthesized

Seongho Jeong

2010-01-01

272

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

273

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

274

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

275

Oxidation/Reduction  

NSDL National Science Digital Library

Created by team members from Kapi'olani Community College and Leeward Community College, this site provides educators and students with a colorful background lesson in oxidation and reduction. The site is divided into concepts, exercises, and everyday examples of oxidation and reduction. Each exercise allows users to check all answers.

276

Oxidative stress in autism  

Microsoft Academic Search

Autism is a severe developmental disorder with poorly understood etiology. Oxidative stress in autism has been studied at the membrane level and also by measuring products of lipid peroxidation, detoxifying agents (such as glutathione), and antioxidants involved in the defense system against reactive oxygen species (ROS). Lipid peroxidation markers are elevated in autism, indicating that oxidative stress is increased in

Abha Chauhan; Ved Chauhan

2006-01-01

277

Oxide Semiconductor Gas Sensors  

Microsoft Academic Search

Semiconductor gas sensors utilize porous polycrystalline resistors made of semiconducting oxides. The working principle involves the receptor function played by the surface of each oxide grain and the transducer function played by each grain boundary. In addition, the utility factor of the sensing body also takes part in determining the gas response. Therefore, the concepts of sensor design are determined

Noboru Yamazoe; Go Sakai; Kengo Shimanoe

2003-01-01

278

Graphite oxidation by moisture  

Microsoft Academic Search

The nature of impurity iron in PGX graphite has been examined and its role during oxidation by steam has been clarified. The iron exists as mobile clusters which are accessible to Hâ and HâO. It can be easily maintained in a reduced or oxidized state by variation of Hâ\\/Hâ pressures. In the reduced state, iron is an active catalyst which

F. B. Growcock; D. Chandra; J. Heiser; J. Jr. Skalyo

1978-01-01

279

Modeling of graphite oxide  

Microsoft Academic Search

Based on density functional calculations, optimized structures of graphite oxide are found for various coverage by oxygen and hydroxyl groups, as well as their ratio corresponding to the minimum of total energy. The model proposed describes well known experimental results. In particular, it explains why it is so difficult to reduce the graphite oxide up to pure graphene. Evolution of

Danil W. Boukhvalov; Mikhail I. Katsnelson

2008-01-01

280

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

281

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

282

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...

283

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

284

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

285

Methane activation: Oxidation goes soft  

NASA Astrophysics Data System (ADS)

Creating useful feedstocks from methane is impeded by over-oxidation when O2 is used as the oxidant. Now, gaseous sulfur has been shown to be a promising 'soft' oxidant for the selective conversion of methane to ethylene.

Keil, Frerich J.

2013-02-01

286

Health Effects of Nitrogen Oxides.  

National Technical Information Service (NTIS)

The oxides of nitrogen of possible concern in air pollution are nitric oxide, nitrogen dioxide, nitrogen pentoxide, inorganic nitrates, and organic nitrates. Available data on the physiologic and toxicologic effects of gaseous nitrogen oxides shows that N...

R. Ziskind D. Hausknecht

1976-01-01

287

Oxidative transformation of carbamazepine by manganese oxides.  

PubMed

This study presents oxidative transformation of carbamazepine by synthetic manganese oxide (?-MnO(2)) as well as impact of variables including initial MnO(2) loading, pH, coexisting metal ions, and humic acid (HA) on transformation. Manganese oxide (?-MnO(2)) was synthesized and stored in the form of suspension. The oxidative reactions were conducted in 50 mL polyethylene (PE) centrifuge tubes with constant pH maintained by buffers. The kinetic experiment was carried out in the solution of pH 2.72 containing 5.0 mg/L of carbamazepine and 130.5 mg/L of MnO(2). Effects of initial MnO(2) loading (0-130.5 mg/L), pH (2.72-8.58) and 0.01 M of coexisting solutes (metal ions and HA) on carbamazepine oxidation were also determined. Reaction kinetics indicated that carbamazepine was rapidly degraded in the first 5 min, and approximately 95 % of carbamazepine was eliminated within 60 min. The reaction exhibited pronounced pH dependence and increased with decreasing pH values. The transformation of carbamazepine was also accelerated with increasing MnO(2) loadings. Coexisting metal ions competed with carbamazepine for reactive sites leading to reduced carbamazepine removal, and the inhibitive capacity followed the order of Mn(2+)?>?Fe(3+)?>?Ca(2+)???Mg(2+). Presence of HA in aqueous solution caused a significant reduction on the magnitude of carbamazepine transformation. This study indicated that carbamazepine can be effectively degraded by ?-MnO(2), and transformation efficiency was strongly dependent on reaction conditions. It suggests that amendment of soil with MnO(2) be a potential alternative to solve carbamazepine pollution. PMID:22565984

He, Yan; Xu, Jian; Zhang, Yuan; Guo, Changsheng; Li, Lei; Wang, Yuqiu

2012-11-01

288

Boric oxide deposition on carbon nanofibers for oxidation resistance.  

PubMed

The boric oxide deposition was performed to improve the oxidation resistivity of carbon nanofiber (CNF) from electrospinning at elevated temperatures. The stabilized electrospun polyacrylonitrile (PAN) nanofibers were coated with boric oxide, followed by heat treatment up to 1000, 1200, and 1400 degrees C in an inert nitrogen atmosphere. The relative oxidation resistance of boric oxide-coated CNFs showed oxidation resistive property, which was determined by weight loss after running a thermogravimetric analyzer (TGA) under air flow. The data were used for the calculations of activation energies through Arrhenius plot. The oxidation resistance of the boric oxide-coated CNFs was depended on the heat treatment temperature, the higher the temperature more resistive to oxidation. The boric oxide-coated CNFs showed extended oxidation resistivity as remaining 40-83% (w) of the original weight at the high temperature 1000 degrees C under air. PMID:23882810

Chae, Hyang Hoon; Kim, Bo-Hye; Yang, Kap Seung; Woo, Hee-Gweon

2013-08-01

289

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

290

Structure of Oxide Surfaces  

NASA Astrophysics Data System (ADS)

Surfaces of metal oxides are of crucial importance for a variety of technological applications such as heterogeneous catalysis, thin film growth, gas sensing, and corrosion prevention. Due to the complexities of oxides in crystal structure and electronic structure, however, the surface science of oxides lags far behind that of metals or semiconductors. Conventional surface-science techniques are usually limited to surfaces of single crystals of conductors. Metal oxides are usually good insulators, making them difficult for conventional surface science techniques. On the other hand, the complex atomic structures of oxides results in too many structural parameters to be determined by spectroscopy or diffraction methods. We will show that the surface structure of oxides can be directly imaged and measured at the sub-angstrom scale using aberration-corrected transmission electron microscopy. The atomic positions of oxide surfaces can be measured to an accuracy of picometers, comparable to that obtained by conventional surface science techniques on single crystals.[4pt] [1] R. Yu, L.H. Hu, Z.Y. Cheng, Y.D. Li, H.Q. Ye, J. Zhu, Phys. Rev. Lett., 105, 226101 (2010).[0pt] [2] M.R. He, R. Yu, J. Zhu, Angew. Chem. Int. Ed., 124, 7864 (2012).

Yu, Rong

2013-03-01

291

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

292

Oxidation of Inconel alloy MA754 at low oxidation potential  

Microsoft Academic Search

It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance was studied. Initial experiments were performed using inconel alloy MA754, which is nominally: 78 Ni,

D. N. Braski; P. D. Goodell; J. V. Cathcart; R. H. Kane

1983-01-01

293

Cuprous Oxide Photovoltaic Cells.  

National Technical Information Service (NTIS)

Methods of junction formation in cuprous oxide photovoltaic cells were investigated for improving light absorption and carrier collection. This report emphasizes the use of front-wall cells, as these are of special interest because of their more favorable...

D. Trivich

1975-01-01

294

Oxidations of Acyclic Alkenes.  

National Technical Information Service (NTIS)

Rates and products of oxidation were determined for ethylene, propylene, 1-butene, 2-butene, isobutylene, trimethylethylene, 3-methyl-1-butene tetramethylethylene, 2-methyl-1-pentene, 1-hexene, t-butylethylene, neopentylethylene, 1-hexyne, and 3-hexyne at...

D. E. Van Sickle F. R. Mayo R. M. Arluck M. G. Syz

1966-01-01

295

Phagocytes and oxidative stress  

Microsoft Academic Search

Neutrophils and other phagocytes manufacture O2? (superoxide) by the one-electron reduction of oxygen at the expense of NADPH. Most of the O2? reacts with itself to form H2O2 (hydrogen peroxide). From these agents a large number of highly reactive microbicidal oxidants are formed, including HOCl (hypochlorous acid), which is produced by the myeloperoxidase-catalyzed oxidation of Cl? by H2O2; OH· (hydroxyl

Bernard M. Babior

2000-01-01

296

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

297

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.

298

Oxidation of Udimet 500  

Microsoft Academic Search

The oxidation behavior of a nickel-cobalt base alloy containing 19% chromium and 3% aluminum was studied in the temperature range of 760–1200°C. The oxidation process at a given temperature was interrupted after 4, 16, and 64 hr, and every 100 hr thereafter, and the specimens were air-cooled, weighed, and subsequently reheated. The weight gain followed the parabolic law, and the

S. K. Rhee; A. R. Spencer

1974-01-01

299

Oxidative methane upgrading.  

PubMed

The economically viable oxidative upgrading of methane presents one of the most difficult but rewarding challenges within catalysis research. Its potential to revolutionalise the chemical value chain, coupled with the associated supremely challenging scientific aspects, has ensured this topic's high popularity over the preceeding decades. Herein, we report a non-exhaustive account of the current developments within the field of oxidative methane upgrading and summarise the pertaining challenges that have yet to be solved. PMID:22848012

Hammond, Ceri; Conrad, Sabrina; Hermans, Ive

2012-09-01

300

Enargite oxidation: A review  

Microsoft Academic Search

Enargite, Cu3AsS4, is common in some deposit types, e.g. porphyry systems and high sulphidation epithermal deposits. It is of environmental concern as a potential source of arsenic. In this communication, we review the current knowledge of enargite oxidation, based on the existing literature and our own original data.Explicit descriptions of enargite oxidation in natural environments are scarce. The most common

Pierfranco Lattanzi; Stefania Da Pelo; Elodia Musu; Davide Atzei; Bernhard Elsener; Marzia Fantauzzi; Antonella Rossi

2008-01-01

301

Nitric oxide, oxidants, and protein tyrosine nitration  

PubMed Central

The occurrence of protein tyrosine nitration under disease conditions is now firmly established and represents a shift from the signal transducing physiological actions of •NO to oxidative and potentially pathogenic pathways. Tyrosine nitration is mediated by reactive nitrogen species such as peroxynitrite anion (ONOO–) and nitrogen dioxide (•NO2), formed as secondary products of •NO metabolism in the presence of oxidants including superoxide radicals (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{O}}_{2}^{{\\bullet}-}\\end{equation*}\\end{document}), hydrogen peroxide (H2O2), and transition metal centers. The precise interplay between •NO and oxidants and the identification of the proximal intermediate(s) responsible for nitration in vivo have been under controversy. Despite the capacity of peroxynitrite to mediate tyrosine nitration in vitro, its role on nitration in vivo has been questioned, and alternative pathways, including the nitrite/H2O2/hemeperoxidase and transition metal-dependent mechanisms, have been proposed. A balanced analysis of existing evidence indicates that (i) different nitration pathways can contribute to tyrosine nitration in vivo, and (ii) most, if not all, nitration pathways involve free radical biochemistry with carbonate radicals (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}{\\mathrm{CO}}_{3}^{{\\bullet}-}\\end{equation*}\\end{document}) and/or oxo–metal complexes oxidizing tyrosine to tyrosyl radical followed by the diffusion-controlled reaction with •NO2 to yield 3-nitrotyrosine. Although protein tyrosine nitration is a low-yield process in vivo, 3-nitrotyrosine has been revealed as a relevant biomarker of •NO-dependent oxidative stress; additionally, site-specific nitration focused on particular protein tyrosines may result in modification of function and promote a biological effect. Tissue distribution and quantitation of protein 3-nitrotyrosine, recognition of the predominant nitration pathways and individual identification of nitrated proteins in disease states open new avenues for the understanding and treatment of human pathologies.

Radi, Rafael

2004-01-01

302

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.

Boskovic, Marija; Vovk, Tomaz; Kores Plesnicar, Blanka; Grabnar, Iztok

2011-01-01

303

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

304

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

305

Gadolinium oxide high- k gate dielectrics prepared by anodic oxidation  

Microsoft Academic Search

The growth and properties of gadolinium oxide (Gd2O3) films prepared by anodic oxidation were investigated. Uniform Gd2O3 thin film with good oxide quality was obtained. The X-ray diffraction (XRD) pattern of the Gd2O3 films showed that they had a poly-crystalline structure. The dielectric constants of Gd2O3 films oxidized at 30 and 60V are 9.4 and 12.2, respectively. The equivalent oxide

P. Y. Kuei; C. C. Hu

2008-01-01

306

Nitrous oxide in oxidation chemistry and catalysis: application and production  

Microsoft Academic Search

An overview is given on extensive studies, which are targeted to involve N2O into organic synthesis as an oxidant. Due to unique oxidative properties, nitrous oxide provides remarkable prospects in catalytic and non-catalytic oxidation chemistry in both gas and liquid phases. The interest to new oxidant resulted in appearance of a new technology for the production of inexpensive N2O too.

V. N. Parmon; G. I. Panov; A. Uriarte; A. S. Noskov

2005-01-01

307

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.  

Code of Federal Regulations, 2010 CFR

...condensates of ethylene oxide and propylene oxide. 172.808 ...of ethylene oxide and propylene oxide. Copolymer condensates of ethylene oxide and propylene oxide may be safely used...followed by potable water rinse. The...

2009-04-01

308

21 CFR 172.808 - Copolymer condensates of ethylene oxide and propylene oxide.  

Code of Federal Regulations, 2010 CFR

...condensates of ethylene oxide and propylene oxide. 172.808 ...of ethylene oxide and propylene oxide. Copolymer condensates of ethylene oxide and propylene oxide may be safely used...followed by potable water rinse. The...

2010-01-01

309

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.

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

2012-01-01

310

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

311

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

312

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

Microsoft Academic Search

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties

Jia-Lin Wu; Chin-Hsing Kao; Hua-Ching Chien; Tzung-Kuen Tsai; Chien-Wei Liao

2007-01-01

313

Raman and IR studies of surface metal oxide species on oxide supports: Supported metal oxide catalysts  

Microsoft Academic Search

Raman and infrared spectroscopy provide complementary information about the nature of the surface metal oxide species present in supported metal oxide catalysts. This paper reviews the type of fundamental information that is typically obtained in Raman and IR characterization studies of supported metal oxide catalysts. The molecular structures of the surface metal oxide species are reflected in the terminal M=O

Israel E. Wachs

1996-01-01

314

Reversible electrical reduction and oxidation of graphene oxide.  

PubMed

We demonstrate that graphene oxide can be reversibly reduced and oxidized using electrical stimulus. Controlled reduction and oxidation in two-terminal devices containing multilayer graphene oxide films are shown to result in switching between partially reduced graphene oxide and graphene, a process which modifies the electronic and optical properties. High-resolution tunneling current and electrostatic force imaging reveal that graphene oxide islands are formed on multilayer graphene, turning graphene into a self-assembled heterostructure random nanomesh. Charge storage and resistive switching behavior is observed in two-terminal devices made of multilayer graphene oxide films, correlated with electrochromic effects. Tip-induced reduction and oxidation are also demonstrated. Results are discussed in terms of thermodynamics of oxidation and reduction reactions. PMID:21391707

Ekiz, Okan Oner; Urel, Mustafa; Güner, Hasan; Mizrak, Alpay Koray; Dâna, Aykutlu

2011-04-26

315

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

316

Erythropoietin and Oxidative Stress  

PubMed Central

Unmitigated oxidative stress can lead to diminished cellular longevity, accelerated aging, and accumulated toxic effects for an organism. Current investigations further suggest the significant disadvantages that can occur with cellular oxidative stress that can lead to clinical disability in a number of disorders, such as myocardial infarction, dementia, stroke, and diabetes. New therapeutic strategies are therefore sought that can be directed toward ameliorating the toxic effects of oxidative stress. Here we discuss the exciting potential of the growth factor and cytokine erythropoietin for the treatment of diseases such as cardiac ischemia, vascular injury, neurodegeneration, and diabetes through the modulation of cellular oxidative stress. Erythropoietin controls a variety of signal transduction pathways during oxidative stress that can involve Janus-tyrosine kinase 2, protein kinase B, signal transducer and activator of transcription pathways, Wnt proteins, mammalian forkhead transcription factors, caspases, and nuclear factor ?B. Yet, the biological effects of erythropoietin may not always be beneficial and may be poor tolerated in a number of clinical scenarios, necessitating further basic and clinical investigations that emphasize the elucidation of the signal transduction pathways controlled by erythropoietin to direct both successful and safe clinical care.

Maiese, Kenneth; Chong, Zhao Zhong; Hou, Jinling; Shang, Yan Chen

2008-01-01

317

Copper oxide nanocrystals.  

PubMed

It is well-known that inorganic nanocrystals are a benchmark model for nanotechnology, given that the tunability of optical properties and the stabilization of specific phases are uniquely possible at the nanoscale. Copper (I) oxide (Cu(2)O) is a metal oxide semiconductor with promising applications in solar energy conversion and catalysis. To understand the Cu/Cu(2)O/CuO system at the nanoscale, we have developed a method for preparing highly uniform monodisperse nanocrystals of Cu(2)O. The procedure also serves to demonstrate our development of a generalized method for the synthesis of transition metal oxide nanocrystals. Cu nanocrystals are initially formed and subsequently oxidized to form highly crystalline Cu(2)O. The volume change during phase transformation can induce crystal twinning. Absorption in the visible region of the spectrum gave evidence for the presence of a thin, epitaxial layer of CuO, which is blue-shifted, and appears to increase in energy as a function of decreasing particle size. XPS confirmed the thin layer of CuO, calculated to have a thickness of approximately 5 A. We note that the copper (I) oxide phase is surprisingly well-stabilized at this length scale. PMID:15984877

Yin, Ming; Wu, Chun-Kwei; Lou, Yongbing; Burda, Clemens; Koberstein, Jeffrey T; Zhu, Yimei; O'Brien, Stephen

2005-07-01

318

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

319

Oxidation in rheumatoid arthritis  

PubMed Central

Oxygen metabolism has an important role in the pathogenesis of rheumatoid arthritis. Reactive oxygen species (ROS) produced in the course of cellular oxidative phosphorylation, and by activated phagocytic cells during oxidative bursts, exceed the physiological buffering capacity and result in oxidative stress. The excessive production of ROS can damage protein, lipids, nucleic acids, and matrix components. They also serve as important intracellular signaling molecules that amplify the synovial inflammatory–proliferative response. Repetitive cycles of hypoxia and reoxygenation associated with changes in synovial perfusion are postulated to activate hypoxia-inducible factor-1? and nuclear factor-?B, two key transcription factors that are regulated by changes in cellular oxygenation and cytokine stimulation, and that in turn orchestrate the expression of a spectrum of genes critical to the persistence of synovitis. An understanding of the complex interactions involved in these pathways might allow the development of novel therapeutic strategies for rheumatoid arthritis.

Hitchon, Carol A; El-Gabalawy, Hani S

2004-01-01

320

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

321

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

322

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

323

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

1993-01-01

324

Oxide Solar Cells Fabricated Using Zinc Oxide and Plasma-Oxidized Cuprous Oxide  

NASA Astrophysics Data System (ADS)

Oxide heterojunction solar cells composed of an n-type Al-doped ZnO (AZO) thin film on the surfaces of p-type Cu2O films were fabricated. The Cu2O films of about 0.34 to 1.67 ?m thickness were grown by partial oxidation of a Cu sheet using microwave plasma. The AZO film of 400 nm thickness was deposited by magnetron sputtering. Energy conversion efficiencies of 0.12 to 0.30% were obtained in AZO/Cu2O cells under AM1.5 solar illumination.

Chan, Yi-Ming; Wu, Ya-Ting; Jou, Shyankay

2012-12-01

325

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

326

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

327

Superstructured tungsten oxide photoanodes  

NASA Astrophysics Data System (ADS)

Tungsten oxide is a robust and stable semiconductor for photoanodic applications in aqueous solutions. Typical deposition techniques like electroplating or sputtering produce granular films which increase interfacial recombination of minority carriers. This has a deleterious effect on the photovoltaic performance of these materials. Using a variety of templating methods, we explore multiscale structuring strategies for increasing the surface area of the photoanode while maintaining significant light absorption. We describe photoelectrochemical and reflectivity measurements on structured and templated tungsten oxide photoanodes and consider how these results guide future photosynthetic electrochemical device design.

Coridan, Robert; Arpin, Kevin; Braun, Paul; Lewis, Nathan

2012-02-01

328

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

329

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

330

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions  

PubMed Central

Summary The application of titanium dioxide as an oxidant in tandem oxidation type processes is described. Under microwave irradiation, quinoxalines have been synthesized in good yields from the corresponding ?-hydroxyketones.

Jeena, Vineet

2009-01-01

331

Uranium oxidation: characterization of oxides formed by reaction with water  

SciTech Connect

Three different uranium oxide samples have been characterized with respect to the different preparation techniques. Results show that the water reaction with uranium metal occurs cyclically forming laminar layers of oxide which spall off due to the strain at the oxide/metal interface. Single laminae are released if liquid water is present due to the prizing penetration at the reaction zone. The rate of reaction of water with uranium is directly proportional to the amount of adsorbed water on the oxide product. Rapid transport is effected through the open hydrous oxide product. Dehydration of the hydrous oxide irreversibly forms a more inert oxide which cannot be rehydrated to the degree that prevails in the original hydrous product of uranium oxidation with water. 27 figures.

Fuller, E.L. Jr.; Smyrl, N.R.; Condon, J.B.; Eager, M.H.

1983-04-27

332

Oxidation of Inconel alloy MA754 at low oxidation potential  

Microsoft Academic Search

It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied. Small disks (3 mm diam x 0.38 mm thick) were cut from

D. N. Braski; P. D. Goodell; J. V. Cathcart; R. H. Kane

1983-01-01

333

Nitrous Oxide Explosive Hazards.  

National Technical Information Service (NTIS)

A recent incident caused us to evaluate the subject of nitrous oxide (N2O) hazards. Use of N2O for rocket propulsion seems to be a continuing interest. Accounts of serious, large system N2O accidents are mysterious since technically satisfying explanation...

C. Merrill

2008-01-01

334

Hydrous oxide activated charcoal  

SciTech Connect

This patent describes a process for preparing of an ion exchanger, comprising: treating an ionically inert activated charcoal porous support with an aqueous solution of metal oxychloride selected from the group consisting of zirconium and titanium oxychlorides so as to impregnate the pores of the support with the solution; separating the treated support from excess metal oxychloride solution; converting the metal oxychloride to a hydrous metal oxide precipitate in the pores of the support at a pH above 8 and above the pH whereat the hydrous metal oxide and activated charcoal support have opposite zeta potentials and sufficient to hydrolyze the metal oxychloride. It also describes a process for preparing an ion exchanger comprising: treating granulated activated charcoal with a concentrated solution of a metal oxychloride from the group consisting of zirconium and titanium oxychlorides, degassing the mixture; and treating the resultant mixture with a base selected from the group consisting of ammonium hydroxide and alkali metal hydroxides so as to precipitate the oxychloride within the pores of the activated carbon granules as hydrous metal oxide at a pH above 8 and above the pH whereat the hydrous metal oxide and activated charcoal have opposite zeta potentials.

Weller, J.P.

1987-09-08

335

Metal oxide sensors  

Microsoft Academic Search

New gas sensors based on novel semiconducting metal oxides are developed. In comparison to the sensors based on SnO2 their properties are improved in several items. The main improvements are the lower influence of humidity, the long-term stability, the ability to start measurement immediately after switch on and reduced unit spread. The sensors will be marketed within this year.

H. Meixner; U. Lampe

1996-01-01

336

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

337

Doped zinc oxide microspheres  

DOEpatents

A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

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

1993-12-14

338

Green Catalytic Oxidations.  

National Technical Information Service (NTIS)

The search for new, clean reactions that can compete with established chemical processes is one of the main challenges of today's chemistry. Recent developments in this area - with a focus on oxidation chemistry - are described in chapter 1. In chapter 2 ...

G. J. Ten Brink

2001-01-01

339

ADMA and oxidative stress  

Microsoft Academic Search

Elevated plasma concentrations of the endogenous nitric oxide synthase (eNOS) inhibitor asymmetric dimethylarginine (ADMA) represent a novel risk factor for the development of endothelial dysfunction and a predictor for all-cause and cardiovascular mortality. However, it is unknown whether elevated ADMA plasma concentrations may be considered simply as a marker for cardiovascular disease or whether increased ADMA levels per se may

Karsten Sydow; Thomas Münzel

2003-01-01

340

Stratospheric aluminum oxide.  

PubMed

Balloons and U-2 aircraft were used to collect micrometer-sized strato-spheric aerosols. It was discovered that for the past 6 years at least, aluminum oxide spheres have been the major stratospheric particulate in the size range 3 to 8 micrometers. The most probable source of the spheres is the exhaust from solid-fuel rockets. PMID:17737717

Brownlee, D E; Ferry, G V; Tomandl, D

1976-03-26

341

Coatings of oxide composites  

NASA Astrophysics Data System (ADS)

During the last decade, coating processes have been extended to the reproducible deposition of composite materials on the basis of simultaneous evaporation or sputtering. Especially, ion beam sputtering from a zone target in conjunction with sophisticated optical broadband monitoring offers several advantages for the production of oxide coatings with defined mixture ratios and even Rugate filter systems with a continuous variation of the composition ratio in the depth of the layer structure. With only two materials on the zone targets, a large dynamic range of refractive index values covering the indices of the pure materials can be achieved. Recent studies on the properties of the produced oxide composites indicate a variety of interesting aspects opened by this new class of material. Among others, a blue shift of the absorption characteristic was observed for ternary oxides, and an increased LIDT, particularly for sub-picosecond coatings, has been reported. Also a number of investigations of fundamental damage mechanisms could be carried out by considering the tunable band gap energy of the coating material. In this endeavor, a group of international collaborators joined in modeling, testing and evaluating the properties of a variety of ternary oxide systems. A verification of principal material qualities was transferred to applicable multilayer coatings in a combined effort. In this paper, an overview on the achievements of these current studies is presented before the background of high power laser applications.

Jensen, Lars O.; Ristau, Detlev

2012-11-01

342

Oxidative stress and autophagy  

PubMed Central

Many neurodegenerative conditions have oxidative stress burdens where levels of reactive oxygen species (ROS) exceed the antioxidant capacity of the neuron. ROS can induce wide-ranging damage in a cell and this is prevented by the activation of antioxidant responses including autophagy. Junkinase (JNK) is stimulated by ROS and mediates antioxidant responses via the activation of the transcriptional activators Fos and Jun (AP-1). In recently published work we examined Drosophila mutants with overgrown larval neuromuscular synapses, mutants that also show all the hallmarks of lysosomal storage disease (LSD). We find that we can reverse this synaptic overgrowth by reducing the oxidative stress burden, and that synaptic overgrowth is mediated by autophagy and JNK-AP-1 activity. We also examined animals defective for protection from oxidative stress and found that they too have synapse overgrowth generated by JNK-AP-1 activity. Treatment of larvae with a known ROS-generating toxin, paraquat, yielded similar synaptic responses. The observations that oxidative stress responses, potentially acting through autophagy, can generate synaptic growth suggest that ROS may be a potent regulator of synapse size and function. These findings have intriguing implications for aging neurons, neurodegenerative conditions and the interpretation of metabolic demand during learning and memory.

West, Ryan JH

2012-01-01

343

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...

344

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

345

Mammalian nitric oxide synthases  

Microsoft Academic Search

The nitric oxide (NO) synthase family of enzymes generate NO from l-arginine, which acts as a biologic effector molecule in a broad number of settings. This report summarizes some of the current information regarding NO synthase structure-function, reaction mechanism, control of catalysis, and protein interactions.

Dennis J Stuehr

1999-01-01

346

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

347

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

348

CONTROLLING SULFUR OXIDES  

EPA Science Inventory

This Research Summary describes EPA's program to develop new and improve existing technologies for sulfur oxides control. As we increasingly turn to coal as the primary utility and industrial fuel, while trying to deal with the problems of acid precipitation, visibility degradati...

349

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

350

Plutonium oxide dissolution.  

National Technical Information Service (NTIS)

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) pro...

J. H. Gray

1992-01-01

351

Epitaxial magnetic oxide heterostructures  

Microsoft Academic Search

Perovskite oxides exhibit a range of physical properties including insulator, semiconductor, metal, superconductor, ferromagnet and many more. Interactions between order parameters result in new properties such as the multiferroic materials. The production of artificial layered epitaxial magnetic heterostructures motivates this research. This requires atomic layer controlled growth which depends on selection of materials for their structural and chemical compatibility, preparation

Land J. Belenky

2006-01-01

352

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

353

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

354

Oxidation of Inconel Alloy MA754 at Low Oxidation Potential.  

National Technical Information Service (NTIS)

It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid en...

D. N. Braski P. D. Goodell J. V. Cathcart R. H. Kane

1983-01-01

355

High-yield electro-oxidative preparation of graphene oxide.  

PubMed

Herein, we report a green electrochemical oxidative approach to convert large quantities of graphite into graphene oxide (GO). The resulted GO flakes have been characterized using various analytical techniques. It was possible to control the degree of oxidation of the produced GO via controlling the electrochemical parameters of the process. PMID:24948081

Abdelkader, A M; Kinloch, I A; Dryfe, R A W

2014-07-01

356

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.

2011-01-01

357

Random Logic Oxide Screening Methods.  

National Technical Information Service (NTIS)

This report covers the work performed on the Random Logic Oxide Screening Methods study in which techniques were investigated to improve oxide reliability screening methods in CMOS random logic devices. This effort included modeling of time dependent diel...

D. N. Krening

1990-01-01

358

Oxidative stress and organ damages.  

PubMed

Oxidative stress plays a pivotal role in various pathological conditions, including hypertension, pulmonary hypertension, diabetes, and chronic kidney disease, with high levels of oxidative stress in target organs such as the heart, pancreas, kidney, and lung. Oxidative stress is known to activate multiple intracellular signaling, which induces apoptosis or cell overgrowth, leading to organ dysfunction. As such, targeting oxidative stress is thought to be effective in protecting against organ damage, and measuring oxidative stress status may serve as a biomarker in diverse disease states. Several new intrinsic anti-oxidative or pro-oxidative factors have recently been reported, and are potential new targets. In the present review, we focus on diabetes, pulmonary hypertension, and renal dysfunction, and their relation with new targets - adrenomedullin, oxidized LDL, and mineralocorticoid receptor. PMID:25011397

Ogura, Sayoko; Shimosawa, Tatsuo

2014-08-01

359

Solid Oxide Electrochemical Reactor Science.  

National Technical Information Service (NTIS)

Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful infor...

A. Ambrosini C. J. Moyer E. B. Stechel N. P. Sullivan R. J. Kee

2010-01-01

360

Staged membrane oxidation reactor system  

SciTech Connect

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

361

Staged membrane oxidation reactor system  

SciTech Connect

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

362

Molecular Assemblies on Oxide Surfaces.  

National Technical Information Service (NTIS)

Our focus for the past 3 years has been on developing a fundamental understanding of the chemical and physical properties of metal complexes on metal oxide surfaces. Carboxylate or phosphonate binding to metal oxide substrates provides a basis for formati...

T. J. Meyer

1998-01-01

363

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

364

Enrofloxacin oxidative degradation facilitated by metal oxide nanoparticles.  

PubMed

The activity of copper oxide, titanium carbide and silicon nitride nanoparticles for the oxidative degradation of environmentally relevant concentrations (?g L(-1) range) of enrofloxacin - an important veterinary antibiotic drug - in aqueous solutions was investigated. With hydrogen peroxide as an oxidative agent, both copper oxide and titanium carbide decrease the concentration of enrofloxacin by more than 90% over 12 h. Addition of sodium halide salts strongly increases the reaction rate of copper oxide nanoparticles. The mechanism for the formation of Reactive Oxygen Species (ROS) was investigated by Electron Spin Resonance (ESR). PMID:22055313

Fink, Lea; Dror, Ishai; Berkowitz, Brian

2012-01-01

365

The anaerobic oxidation of ammonium  

Microsoft Academic Search

From recent research it has become clear that at least two different possibilities for anaerobic ammonium oxidation exist in nature. `Aerobic' ammonium oxidizers like Nitrosomonas eutropha were observed to reduce nitrite or nitrogen dioxide with hydroxylamine or ammonium as electron donor under anoxic conditions. The maximum rate for anaerobic ammonium oxidation was about 2 nmol NH+4 min?1 (mg protein)?1 using

Mike S. M Jetten; Marc Strous; Katinka T van de Pas-Schoonen; Jos Schalk; Udo G. J. M van Dongen; Astrid A van de Graaf; Susanne Logemann; Gerard Muyzer; Mark C. M van Loosdrecht; J. Gijs Kuenen

1998-01-01

366

Electrochemical oxidation of chlorinated phenols  

Microsoft Academic Search

Electrochemical oxidation has been proposed as a remediation method for chlorinated phenols but is hampered by anode fouling. In this work the authors explore the mechanism of anode fouling by chlorinated phenols, compare structure vs reactivity for phenols differing in the extent of chlorination, and relate the efficiency of oxidation to the mechanism of oxidation at different electrode types. Linear

James D. Rodgers; Wojciech Jedral; Nigel J. Bunce

1999-01-01

367

Oxidative Phosphonylation of Aromatic Compounds  

Microsoft Academic Search

Aryl phosphonates can be prepared in good yields from the respective arenes and tri- or dialkylphosphites by either chemical or electrochemical oxidation The anodic oxidation proceeds either via phosphonium radical cations which then attack the arenes electrophilically or via arene radical cations which add the trialkyl-phosphite as nucleophile. Aryl phosphonates are also obtained in good yields by chemical oxidation with

Franz Effenberger; Hariolf Kottmann

1987-01-01

368

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

369

Oxidation of thin scandium films  

Microsoft Academic Search

Thin Sc films (namely, 20 layers or thinner) are studied as a function of oxygen exposure using Auger Electron Spectroscopy (AES) and Temperature Programmed Desorption (TPD) measurements. While AES data indicate that surface Sc layers oxidize rapidly, TPD data indicate that at room temperature the oxidation process is confined to the top layers. The surface oxide layer, about 5 layers

A. Shih; J. E Yater; C Hor; R Abrams

2003-01-01

370

Oxides Heterostructures for Nanoelectronics  

SciTech Connect

We summarise in this paper the work of two groups focusing on the synthesis and characterisation of functional oxide for nanoelectronic applications. In the first section, we discuss the growth by liquid-injection MOCVD of oxides heterostructures. Interface engineering for the minimisation of silicate formation during the growth of polycrystalline SrTiO{sub 3} on Si is first presented. It is realised via the change of reactant flow or chemical nature at the Si surface. We then report on the epitaxy on oxide substrates of manganites films and superlattices and on their magnetic and electrical properties. La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and La{sub 0.8}MnO{sub 3-{delta}} as well as multiferroic hexagonal ReMnO{sub 3} manganites are considered. We show that the film thickness and related strain may be used to tune the properties. Finally, we demonstrate the growth of MgO nanowires by CVD at a moderate temperature of 600 C, using gold as a catalyst. In the second section, we discuss the growth of epitaxial oxide heterostructures by MBE. First, the direct epitaxy of SrTiO{sub 3} on Si is considered. Issues and control of the SrTiO{sub 3}/Si interface are discussed. An abrupt interface is achieved. We show that SrTiO{sub 3} on Si can be used as a buffer layer for the epitaxy of various perovskite oxides such as LaAlO{sub 3} or La{sub 0.7}Sr0.3MnO{sub 3}. La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films are ferromagnetic and metallic at room temperature. The epitaxial growth of complex oxides on Si wafers opens up the route to the integration of a wide variety of functionalities in nanoelectronics. Finally, we discuss the monolithic integration of III-V compounds such as InP on Si using epitaxial SrTiO{sub 3} buffer layers for the future integration of optics on Si.

C Dubourdieu; I Gelard; O Salicio; G Saint-Girons; B Vilquin; G Hollinger

2011-12-31

371

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

372

Anodic oxidation of vanadium and properties of vanadium oxide films  

NASA Astrophysics Data System (ADS)

Thin films of amorphous vanadium oxide have been prepared by electrochemical anodic oxidation. The phase composition of anodic films on vanadium has been shown to depend on the oxidation conditions (electrolyte composition, oxidation current, and time), and the stoichiometry can be controlled from V O2 to V2O5. Physical properties of the oxide films, including the metal-insulator transition in amorphous V O2, are studied. In addition, it is shown that non-equilibrium electrochemical oxidation leads to the formation of metastable vanadium oxides with extremely high sensitivity to laser ({\\sim }1~{\\mathrm {mJ~cm^{-2}}} ) and electron-beam ({\\sim }10~\\micmu {\\mathrm {C~cm}}^{-2} ) irradiation. Such films are of considerable technical interest, particularly because of potential applications as an efficient resist material for both photonanolithography and electron-beam nanolithography.

Stefanovich, G. B.; Pergament, A. L.; Velichko, A. A.; Stefanovich, L. A.

2004-06-01

373

Oxidation of Inconel alloy MA754 at low oxidation potential  

SciTech Connect

It has been known for some time that the addition of small oxide particles to an 80 Ni-20 Cr alloy not only increases its elevated-temperature strength, but also markedly improves its resistance to oxidation. The mechanism by which the oxide dispersoid enhances the oxidation resistance is being studied. Small disks (3 mm diam x 0.38 mm thick) were cut from Inconel MA754 plate stock and prepared with two different surface conditions. Disks having both surface treatments were oxidized in a radiantly heated furnace for 30 s at 1000/sup 0/C. Three different environments were investigated: hydrogen with nomninal dew points of 0/sup 0/C, -25/sup 0/C, and -55/sup 0/C. The oxide particles and films were examined in TEM by using extraction replicas (carbon) and by back-polishing to the oxide/metal interface. The particles were analyzed by EDS and SAD.

Braski, D.N.; Goodell, P.D.; Cathcart, J.V.; Kane, R.H.

1983-01-01

374

Oxidation of Tungsten and Other Refractory Metals.  

National Technical Information Service (NTIS)

Contents: Methods for studying high temperature oxidation reactions, High pressure oxidation of refractory metals - experimental methods and interpretation, Initial stages of the oxidation of tungsten and tantalum, Four types of oxidation processes in the...

1965-01-01

375

Supercritical Water Oxidation Data Acquisition Testing.  

National Technical Information Service (NTIS)

Supercritical Water Oxidation (SCWO) is a high pressure oxidation process that blends air, water, and organic waste material in an oxidizer in which where the temperature and pressure in the oxidizer are maintained above the critical point of water. Super...

K. M. Garcia

1996-01-01

376

Strength of Nonuniformly Oxidized PGX Graphite.  

National Technical Information Service (NTIS)

Flexural and tensile tests were performed on PGX graphite oxidized to produce a steep surface oxidation gradient. Companion tensile specimens were oxidized under different conditions to produce uniform oxidation throughout the specimen, and their tensile ...

R. J. Price L. A. Beavan

1981-01-01

377

Oxidation resistant copper  

SciTech Connect

Oxidation resistant particles composed of copper and at least one metal having a valence of +2 or +3 and having an intermediate lattice energy for the metal in its hydroxide form. The metal is selected from nickel, cobalt, iron, manganese, cadmium, zinc, tin, magnesium, calcium and chromium. In one embodiment, the phases of copper and at least one metal in the particles are separate and the concentration of the metal is greater near the surface of the particles than inwardly thereof. Process for making the oxidation resistant copper particles includes the steps of dissolving a copper salt and a salt of at least one of the metals in a suitable solvent or diluent; forming primary particles of copper and at least one metal in basic form by mixing a base and the salt solution; separating, washing and drying the primary particles; reducing the primary particles to metallic form; and heat treating the particles in metallic form at an elevated temperature.

Edelstein, A.S.; Kaatz, F.H.; Harris, V.G.

1993-11-15

378

Oxidative protein folding  

PubMed Central

During seed development, endosperm cells of highly productive cereals, including rice, synthesize disulfide-rich proteins in large amounts and deposit them into storage organelles. Disulfide bond formation involves electron transfer and generates H2O2 as a by-product. To ensure proper development and maturation of seeds, the endosperm cells must supply large amounts of oxidizing equivalents to dithiols in nascent proteins in a controlled manner. This review compares multiple oxidative protein folding systems in yeast, cultured human cells, and rice endosperm. We discuss possible roles of ERO1, other sulfhydryl oxidases, and the protein disulfide isomerase family in the formation of disulfide bonds in storage proteins and the development of protein bodies. Rice prolamins, encoded by a multigene family, are divided into Cys-rich and Cys-depleted subgroups. We discuss the potential importance of disulfide bond formation in the evolution of the prolamin family in japonica rice.

Onda, Yayoi

2011-01-01

379

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

380

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

381

Controlled CO preferential oxidation  

DOEpatents

Method for controlling the supply of air to a PROX 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 therebetween 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.

Meltser, Mark A. (Pittsford, NY) [Pittsford, NY; Hoch, Martin M. (Webster, NY) [Webster, NY

1997-01-01

382

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

383

Oxide heterostructure resistive memory.  

PubMed

Resistive switching devices are widely believed as a promising candidate for future memory and logic applications. Here we show that by using multilayer oxide heterostructures the switching characteristics can be systematically controlled, ranging from unipolar switching to complementary switching and bipolar switching with linear and nonlinear on-states and high endurance. Each layer can be tailed for a specific function during resistance switching, thus greatly improving the degree of control and flexibility for optimized device performance. PMID:23724783

Yang, Yuchao; Choi, ShinHyun; Lu, Wei

2013-06-12

384

Titania Silica Mixed Oxides  

Microsoft Academic Search

Various titania-silica aerogels prepared by an alkoxide-sol-gel route have been tested in the epoxidation of bulky olefins using cumene hydroperoxide as oxidant. The drying method, the titanium content between 2 and 20 wt%, and the calcination temperature between 473 and 1073 K were the most important preparation parameters, influencing the catalytic behaviour of the aerogels. The aerogels dried by semicontinuous

R. Hutter; T. Mallat; A. Baiker

1995-01-01

385

Iron oxide pillared graphite.  

PubMed

We show that alpha-Fe2O3- and Fe3O4-pillared graphites can be prepared by pillaring graphite oxide with trinuclear iron acetato complex ion and calcining it in air and in vacuo, respectively. A pillared graphite structure is confirmed by transmission electron microscopy observations. The adsorption isotherms of water indicate that the mesopores of Fe3O4-pillared graphite constitute a hydrophobic nanospace. PMID:15982031

Morishige, Kunimitsu; Hamada, Takanobu

2005-07-01

386

Dilute magnetic semiconducting oxides  

Microsoft Academic Search

A review of recent results on transition metal doping of electronic oxides such as ZnO, TiO2, SnO2, BaTiO3, Cu2O, SrTiO3 and KTaO3 is presented. There is interest in achieving ferromagnetism with Curie temperatures above room temperature in such materials for applications in the field of spintronic devices, in which the spin of the carriers is exploited. The incorporation of several

S J Pearton; W H Heo; M Ivill; D P Norton; T Steiner

2004-01-01

387

Tropospheric nitric oxide measurements  

NASA Technical Reports Server (NTRS)

Nitric oxide (NO) plays a key role in tropospheric photo-chemistry. The photochemical oxidation of hydrocarbons, for example, can serve as either a source or a sink for ozone, depending on the local abundance of NO. Nitric oxide also helps govern atmospheric concentrations of the hydroxyl (OH) radical. The OH radical is the single most important player in photochemical transformations because it controls the atmospheric lifetimes of so many chemical species. Although NO serves as a very effective catalyst in many important chemical processes, its concentration is low enough to normally be expressed in units of parts per trillion by volume (pptv). Consequently, commercially available detectors for NO (with detection limits of about one part per billion) have proven to be unsuitable for use anywhere except in urban areas and near other local pollution sources. Under the sponsorship of NASA's Global Tropospheric Experiment (GTE), Wallops has developed an extremely sensitive detector with a detection limit of a few pptv. The system was specifically designed for aircraft use, with the objective of applying it in global aircraft studies of tropospheric chemistry. Studies with the detector are examined.

Torres, A. L.

1988-01-01

388

Magnetic Oxide Superlattices  

NASA Astrophysics Data System (ADS)

Atomically regulated interfaces and superlattices composed of oxides are very interesting research arena for physics and possible applications. By selecting magnetic oxides as one of the components, one can study basic phenomena of spin polarized electrons at the interfaces [1]. Also, one can realized ?multiferroics? at the interface because magnetization and electric dipole due to interface charge imbalance can coexist. We demonstrated that non-linear Kerr effect [2] can be a tool of detecting interface magnetism in ?tricolor superlattices? composed of asymmetric A-B-C-A-B-C- sequence with A, B, and C being component oxides [3]. This technique was successfully applied to detect, design and enhance interface magnetism in a single heterointerface [4]. We now extend the artificially built-in multiferroic superlattices to other sequences, which include DNA superlattices (D: donor, N: neutral, and A: acceptor) and Ratchet superlattices (asymmetric doping profile). We also demonstrate realization of interface ferromagnetism at pn junctions made of two Mott insulators and tuning the magnitude through the channels of orbital and charge degrees of freedom. [1] M. Izumi et. al., J. Phys. Soc. Jpn., 71, 2621 (2002), Phys. Rev. B 64, 064429 (2001). [2] Y. Ogawa, et. al., Phys. Rev. Lett., 90. 217403 (2003). [3] H. Yamada, at. al., Appl. Phys. Lett., 80, 622 (2002). [4] H. Yamada, et. al., Science, 305, 646 (2004).

Kawasaki, Masashi

2006-03-01

389

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.

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

2007-01-01

390

Molecular theory of graphene oxide.  

PubMed

Applied to graphene oxide, the molecular theory of graphene considers its oxide as a final product in the succession of polyderivatives related to a series of oxidation reactions involving different oxidants. The graphene oxide structure is created in the course of a stepwise computational synthesis of polyoxides of the (5,5) nanographene molecule governed by an algorithm that takes into account the molecule's natural radicalization due to the correlation of its odd electrons, the extremely strong influence of the structure on properties, and a sharp response of the molecule behavior on small actions of external factors. Taking these together, the theory has allowed for a clear, transparent and understandable explanation of the hot points of graphene oxide chemistry and suggesting reliable models of both chemically produced and chemically reduced graphene oxides. PMID:23851966

Sheka, Elena F; Popova, Nadezhda A

2013-08-28

391

Oxidation of Platinum Resistance Thermometers  

NASA Astrophysics Data System (ADS)

PRTs were soaked at different temperatures, and the resulting changes caused by oxidation and the subsequent dissociation of the formed oxide were observed. Soaking below 400 °C initiated oxidation, in some platinum resistance thermometers (PRTs), and then their resistance steadily increased with increasing temperatures up to about 525 °C. When soaking near 525 °C, the resistance of the PRT remained stable, suggesting that the thermal energy ``kT'' equals the energy that binds oxygen to platinum, at the existing oxygen pressure. At temperatures higher than 525 °C the formed oxide dissociated. The higher the temperature, the higher the thermal energy and thus the higher the rate of dissociation. One hour of soaking near the Al point dissociated the oxide that took hundreds of hours to accumulate. Three out of seven PRTs tested however would not oxidize while soaking for several months. Further soaking, however, did initiate oxidation in two of the three PRTs.

Ancsin, John

2003-09-01

392

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

393

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

394

Zinc-indium-oxide: A high conductivity transparent conducting oxide  

Microsoft Academic Search

We report the fabrication and characterization of zinc-indium-oxide films with similar electrical conductivity and better transparency in both the visible and infrared compared with indium–tin–oxide, a widely used transparent conductor in many technological applications. Dramatically superior transmission properties in the 1–1.5 ?m range in particular make zinc–indium–oxide attractive for use in infrared devices, where transparent electrodes are required. Resisitivities as

Julia M. Phillips; R. J. Cava; G. A. Thomas; S. A. Carter; J. Kwo; T. Siegrist; J. J. Krajewski; J. H. Marshall; W. F. Peck Jr.; D. H. Rapkine

1995-01-01

395

Renal oxidant injury and oxidant response induced by mercury  

Microsoft Academic Search

Renal oxidant injury and oxidant response induced by mercury. The role of oxidative stress in mercuric chloride (HgCl2)-induced nephrotoxicity is uncertain and controversial. We demonstrate that LLC-PK1 cells, exposed to HgCl2, generate massive amounts of hydrogen peroxide, the latter completely quenched by the hydrogen peroxide scavenger, pyruvate. HgCl2 exerts a dose-dependent cytotoxicity which is attenuated by pyruvate and catalase. Cellular

Karl A Nath; Anthony J Croatt; Scott Likely; Tim W Behrens; David Warden

1996-01-01

396

Electrodeposited cuprous oxide on indium tin oxide for solar applications  

Microsoft Academic Search

Semiconducting cuprous oxide films were prepared by electrodeposition onto commercial conducting glass coated with indium tin oxide deposited by spraying technique. The cuprous oxide (Cu2O) films were deposited using a galvanostatic method from an alkaline CuSO4 bath containing lactic acid and sodium hydroxide at a temperature of 60°C. The film's thickness was about 4–6?m. This paper includes discussion for Cu2O

V. Georgieva; M. Ristov

2002-01-01

397

Hydrothermal synthesis of vanadium oxide nanotubes from oxide precursors.  

PubMed

Vanadium oxide nanotubes were synthesized as the main product by a direct hydrothermal treatment of oxide precursors and long chain amines as structure-directing templates. The morphology and structure of nanotubes was characterized by powder X-ray diffraction, electron microscopy, and thermal analysis. Nanotubes of high aspect ratio with layered structures were found to grow together in the form of bundles. The paper also discusses the chemistry issues involved in synthesizing nanostructured vanadium oxides. PMID:17654977

Sharma, S; Thomas, J; Ramanan, A; Panthöfer, M; Jansen, M

2007-06-01

398

Mercury oxidation by copper oxides in combustion flue gases  

Microsoft Academic Search

The two main gaseous mercury species in combustion flue gas are elemental mercury (Hg0) and oxidized mercury (Hg2+). In the coal combustion process using an installed wet FGD system, Hg2+ is captured and Hg0 emitted since Hg2+ is soluble in water. Oxidation of Hg0 upstream of the FGD would significantly reduce Hg emission. In the presence of CuO nanoparticles, oxidation

Akimasa Yamaguchi; Hiroyuki Akiho; Shigeo Ito

2008-01-01

399

Oxidative dimerization of methane over sodium-promoted calcium oxide  

Microsoft Academic Search

Sodium-promoted calcium oxides are active and selective catalysts for the partial oxidation of methane to ethane and ethylene using molecular oxygen as an oxidant. In a conventional fixed-bed flow reactor, operating at atmospheric pressure, a 45% Câ (sum of ethane and ethylene) selectivity was achieved at a 33% methane conversion over 2.0 g of 15 wt% Na\\/CaO catalyst at 725°C

C. Lin; J. Wang; J. H. Lunsford

1988-01-01

400

Alumina composites for oxide\\/oxide fibrous monoliths  

Microsoft Academic Search

Most work on ceramic fibrous monoliths (FMs) has focused on the SiâNâ\\/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,

T. A. Cruse; B. J. Polzin; J. J. Picciolo; D. Singh; R. N. Tsaliagos; K. C. Goretta

2000-01-01

401

Oxidation of sulfites on vanadium-molybdenum oxides  

NASA Astrophysics Data System (ADS)

The low temperature emission of 1O2 singlet oxygen from xV2O5 · yMoO3 binary oxides is investigated by means of flash desorption. Conditions for the generation of 1O2 on their surfaces are determined, along with the correlation between the amount of 1O2 and the degree of NaHSO3 conversion in the oxidation reaction. It is shown that on the surface of oxides there are oxygen species that upon decomposition produce 1O2 involved in the oxidation of HSO{3/-}.

Matrosova, O. V.; Vishnetskaya, M. V.

2014-01-01

402

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

403

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

404

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

405

[Oxidative stress in nephrology].  

PubMed

The effect of reactive oxygen species (ROS) on pathophysiology of many diseases is widely documented in numerous scientific publications. Nephropathies belong to pathologies in which ROS undoubtedly play a role. Imbalance between ROS and antioxidants results in destructive effect on mesangial cells by altering lipid metabolism. This phenomenon is frequently observed in patients with glomerulonephritis and nephritic syndrome. Accumulation of hypoxanthine and oxygen in the mechanism of reperfusion damages renal cells by the produced ROS in patients with acute renal failure. Inactivation of nitric oxide by superoxide anion radical increases vascular resistance in renal arteries and contributes to the development of hypertensive nephropathy. Diabetic nephropathy, in which a significant role is ascribed to glycation end products, oxidative stress and decrease of antioxidant mechanisms, is another nephropathy associated with oxidant/antioxidant imbalance. Pro-inflammatory processes with activation of nonspecific system cells and destruction of kidney structure by free radical processes play an important role in urinary system infections. Similar phenomena are observed in patients with urinary system neoplastic diseases. Each of the above pathological conditions may in consequence lead to chronic renal failure (CRF) requiring nephro-substitute therapy. The therapy substituting for normal kidney function but not devoid of disadvantages. Despite of the application of numerous techniques of detoxification in patients with CRF, none of them has become the "gold standard" yet, because according to the so far carried out research they all induce free radical reactions in the course of dialysis and decrease total antioxidant potential of plasma. It is a very crucial problem of nephro-substitute therapy which will be developed in our next review paper. PMID:20369727

Pedzik, Adrianna; Paradowski, Marek; Rysz, Jacek

2010-01-01

406

Ultra supercritical steamside oxidation  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, which are part of the U.S. Department of Energy's Vision 21 goals. 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. Vision 21 goals include steam temperatures of up to 760 C. This research examines the steamside oxidation of advanced alloys for use in USC systems. Emphasis is placed on alloys for high- and intermediate-pressure turbine sections. Initial results of this research are presented.

Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Ziomek-Moroz, M.; Alman, David A.; Ochs, Thomas L.

2004-01-01

407

Magnetic Oxide nanoparticles  

Microsoft Academic Search

We have fabricated nanopillar arrays of epitaxial magnetic oxide thin films and heterostructures consisted of SrRuO3, La0.67Sr0.33MnO3 and insulating barrier. The films were grown on TiO2 surface terminated (001) SrTiO3 substrates with atomic layer control by pulsed laser deposition with in situ high pressure RHEED, and were patterned into nanopillars using e-beam lithography and neutralized Ar ion milling with Ti

D. Ruzmetov; L. J. Belenky; X. Ke

2005-01-01

408

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.

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

2011-01-01

409

[Increasing oxidative stress in aging].  

PubMed

The balance between reactive oxigen species (ROS) production and degradation is important in defining oxidative stress. In aging process, ROS production increases and degradation is impaired and thus oxidative stress is accumulated. Oxidative stress damages organs both directly and indirectly. Protein, lipid, as well as DNA are directly react with ROS, more over, ROS interact with intracellular signaling system. It is reported that several transcription factors such as NF-kappaB, AP-1 and ASK-1 and also it interferes MAPK activity. Besides these signaling, we recently showed that insulin resistance is induced by accumulated oxidative stress in aged mice. Adrenomedullin deficient mice accumulate higher oxidative stress and insulin resistance developed in aging. Oxidative stress in aging relates not only direct organ damage but also induce risk factors for vascular damage such as metabolic syndrome. PMID:15948381

Shimosawa, Tatsuo

2005-06-01

410

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors that includes 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, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

411

Zinc oxide varistors and/or resistors  

SciTech Connect

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

412

Oxidative stress and diabetes mellitus  

Microsoft Academic Search

Oxidative stress is increased in diabetes mellitus and may play an important role in the pathogenesis of the typical long-term complications of human diabetes, like neuropathy and microangiopathy. Protein glycation and glucose autoxidation can generate free radicals that can catalyze lipid peroxidation. Other potential mechanisms of oxidative stress include the reduction of anti-oxidant defense. The role of endothelium-dependent vasodilatation and

J. P Kuyvenhoven; A. E Meinders

1999-01-01

413

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

414

Pyrite oxidation by thermophilic archaebacteria  

SciTech Connect

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 autotropbically 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.

Larsson, L.; Olsson, G.; Holst, O.; Karlsson, H.T. (Lund Univ. (Sweden))

1990-03-01

415

Solid oxide electrochemical reactor science  

Microsoft Academic Search

Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid

Neal P. Sullivan; Ellen Beth Stechel; Connor J. Moyer; Andrea Ambrosini; Robert J. Key

2010-01-01

416

Angiotensin II and Oxidative Stress  

Microsoft Academic Search

\\u000a There is an increasing body of evidence that oxidative stress markedly contributes to endothelial dysfunction and to poor\\u000a prognosis in patients with coronary artery disease and hypertension. Among many stimuli for oxidative stress in vascular tissue,\\u000a the role of angiotensin II has been extensively studied. When given acutely, angiotensin II stimulates the release of nitric\\u000a oxide and activates a nonphagocytic

N. Tsilimingas; A. Warnholtz; M. Wendt; T. Münzel

417

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

418

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.

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

1990-01-01

419

Computer Simulation Of Cyclic Oxidation  

NASA Technical Reports Server (NTRS)

Computer model developed to simulate cyclic oxidation of metals. With relatively few input parameters, kinetics of cyclic oxidation simulated for wide variety of temperatures, durations of cycles, and total numbers of cycles. Program written in BASICA and run on any IBM-compatible microcomputer. Used in variety of ways to aid experimental research. In minutes, effects of duration of cycle and/or number of cycles on oxidation kinetics of material surveyed.

Probst, H. B.; Lowell, C. E.

1990-01-01

420

Inorganic halogen oxidizers  

NASA Astrophysics Data System (ADS)

A research program was carried out in novel energetic materials. This program was highly successful and resulted in 28 major publications. Highlights of this effort include: the characterization of the XeF5(-) anion which is the first example of a pentagonal planar XY5 structure, completion of our work on a quantitative oxidizer strength scale, the synthesis and characterization of new compounds at the limits of coordination and oxidation, such as XeOF5(-), TeOF6(2-), IOF6(-), IF8(-), TeF8(2-), TeF7(-), and XeF7(+), the study of fluxionality and steric repulsion effects in hexa- and hepta- coordinated species, such as IF7, HPF5(-), HSF5, and IOF5, the controlled replacement of two fluorine ligands by one doubly bonded oxygen ligand, studies of the thermal instability of NF5 and the F3(-) anion, the characterization of the N2F(+) cation N(CH3)4N3, H2N3(+) cation and the SF4(-) and SOF4(-) radical anions, the synthesis and characterization of a new Os(+VIII) compound, OsF4O2, theoretical studies on ONOF and a new family of polynitrogen compounds, the synthesis and characterization of the novel PF4(-) anion and it hydrolysis products, and the electrophilic fluorination of CH4 with F(+) equivalent N2F(+) and NF4(+) salts.

Christe, K. O.; Wilson, W. W.

1994-09-01

421

Magnetic Oxide nanoparticles  

NASA Astrophysics Data System (ADS)

We have fabricated nanopillar arrays of epitaxial magnetic oxide thin films and heterostructures consisted of SrRuO3, La0.67Sr0.33MnO3 and insulating barrier. The films were grown on TiO2 surface terminated (001) SrTiO3 substrates with atomic layer control by pulsed laser deposition with in situ high pressure RHEED, and were patterned into nanopillars using e-beam lithography and neutralized Ar ion milling with Ti and Au as milling mask materials. Scanning electron and atomic force microscopy measurements confirmed that we have produced well defined diameter 100 nm and 40 nm tall pillar arrays, which are, to our knowledge, the smallest pillars made from magnetic perovskite oxides. The LSMO pillars whose dimensions are smaller than the domain size (˜150nm) and comparable to the exchange length (˜50nm) are ferromagnetic at room temperature as shown by magnetic force microscopy. Using multilevel e-beam lithography we made single nano-ellipses from LSMO and SRO and wired them individually with Au leads. We performed electron transport measurements at 5K aiming to measure anisotropic magnetoresistance and coercive fields of single nano-ellipses ranging in size from 850 x 400 nm^2 to 400 x 150nm^2. Supported by NSF-ECS 0210449.

Ruzmetov, D.; Belenky, L. J.; Ke, X.

2005-03-01

422

Biotransformation of nitric oxide.  

PubMed Central

Previous investigations into the health effects of nitrogen oxides (NOx) have mostly been conducted with special reference to nitrogen dioxide (NO2) and its direct effects on the respiratory system, while the study of nitric oxide (NO) has been disregarded. We carried out a study on NO by exposing rats and mice to 15NO or administering 15N-nitrite and 15N-nitrate to these animals by IP injection in order to elucidate the metabolic fate of NO. The results of our study and previous findings led us to assume that the major metabolic path of inhaled NO is as follows: inhaled NO reacts with hemoglobin, forming nitrosyl-hemoglobin (NOHb), and from NOHb, nitrite (NO2-) and nitrate (NO3-) are generated. Major quantities of NO3- are discharged into the urine and a certain amount is discharged into the oral cavity through the salivary glands and transformed to NO2-. Part of this NO2- is converted to N2 gas in the stomach. Nitrate in the intestine is partly reduced to ammonia (NH3) through NO2-, reabsorbed into the body, and converted to urea. Most of the metabolites of inhaled NO are excreted rapidly from the body within 48 hr.

Yoshida, K; Kasama, K

1987-01-01

423

Oxidation resistant coatings for molybdenum  

SciTech Connect

As an article of manufacture, a molybdenum element is described comprising a molybdenum substrate in which the substrate has adherently bonded thereto a thermally self-healing plasma-sprayed coating consisting essentially of a composite of molybdenum and a refractory oxide material capable of reacting with molybdenum oxide under oxidizing conditions to form a substantially thermally stable refractory compound of molybdenum. The plasma-sprayed coating is formed of interbonded plasma-sprayed layers of a composite of molybdenum/refractory oxide material produced from a particulate mixture thereof. The bonded layers range from a first layer adjacent to the substrate to an Nth or last layer.

Timmons, G.A.

1988-05-17

424

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

425

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

426

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.

2010-03-22

427

Permeability of oxidized phosphatidylcholine liposomes.  

PubMed

Permeability of liposomes made from mixtures of unoxidized and singlet oxygen oxidized phosphatidylcholine has been related to the degree of lipid oxidation expressed as hydroperoxide moiety content in the lipids. The effect of oxidation on the liposomes permeability has been studied by fluorometry using calcein as a fluorescent probe that undergoes self quenching when highly concentrated inside liposomes. The liposomes containing 73% and 5% of hydroperoxides retain respectively 64.5 and 96.3% of calcein with respect to that retained by the liposomes made from unoxidized phosphatidylcholine. The fluorescence data show a linear relationship between the liposome permeability and the oxidation degree of lipids. PMID:2775263

Tanfani, F; Bertoli, E

1989-08-30

428

Novel method for controlled oxidation  

SciTech Connect

The purpose of this paper is to describe a novel method for the oxidative degradation of coal or other organic material. The procedure is potentially useful for structure determination. As originally conceived, this method was intended for use with aqueous potassium permanganate as oxidant, but it is equally applicable with other oxidizing agents. Sodium hyprochlorite can be substituted for KMnO/sub 4/ except that controlling the pH and monitoring the end pilot become more difficult. Results with potassium permanganate only are described here but sodium hypochlorite was tried. An advantageous feature of the method is the simultaneous removal of soluble products from further contact with oxidizing agent as the oxidizing agent attacks the substrate. In principle, the experimental approach resembles that of column chromatography. Any oxidative degradation of a natural product for structure determination is of little use if carried out too far; for example, to the smallest, most oxidation-resistant materials such as carbon dioxide, acetic acid, and benzoic acid. Potassium permanganate oxidations of reactive species such as coal and kerogen are particularly difficult to control. Partially oxidized fragments which go into solution can be attacked more effectively than the solid starting phase, a situation which results in loss of structural information. Another difficulty is that phenolic materials can undergo coupling reactions thus generating larger molecules and giving misleading results due to a larger number of substituents. The procedure used is described.

Benjamin, B.M.; Raaen, V.F.

1981-01-01

429

High dielectric constant gate oxides for metal oxide Si transistors  

NASA Astrophysics Data System (ADS)

The scaling of complementary metal oxide semiconductor transistors has led to the silicon dioxide layer, used as a gate dielectric, being so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (?) or 'high K' gate oxides such as hafnium oxide and hafnium silicate. These oxides had not been extensively studied like SiO2, and they were found to have inferior properties compared with SiO2, such as a tendency to crystallize and a high density of electronic defects. Intensive research was needed to develop these oxides as high quality electronic materials. This review covers both scientific and technological issues—the choice of oxides, their deposition, their structural and metallurgical behaviour, atomic diffusion, interface structure and reactions, their electronic structure, bonding, band offsets, electronic defects, charge trapping and conduction mechanisms, mobility degradation and flat band voltage shifts. The oxygen vacancy is the dominant electron trap. It is turning out that the oxides must be implemented in conjunction with metal gate electrodes, the development of which is further behind. Issues about work function control in metal gate electrodes are discussed.

Robertson, John

2006-02-01

430

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

431

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

432

Thermal Expansion Anisotropy of Oxides and Oxide Solid Solutions.  

National Technical Information Service (NTIS)

The thermal expansion properties of the oxides stishovite (the rutile form of SiO2), tetragonal vanadium dioxide, and zincite (ZnO) were measured. Solid solutions of rutile-, corundum-, and zincite-structure oxides were prepared, and the thermal expansion...

H. P. Kirchner

1969-01-01

433

Process for reducing nitrogen oxides without generating nitrous oxide  

SciTech Connect

This patent describes a process for the reduction of the concentration of nitrogen oxides in the oxygen rich effluent from the combustion of a carbonaceous fuel, the process comprises: introducing a treatment agent which comprises ammonium carbamate into the effluent which is at a temperature greater than about 1300{degrees} F and in an amount effective to substantially avoid the presence of nitrous oxide.

Hofmann, J.E.; Sprague, B.N.; Sun, W.H.

1991-03-05

434

Semiconductor-oxide heterostructured nanowires using postgrowth oxidation.  

PubMed

Semiconductor-oxide heterointerfaces have several electron volts high-charge carrier potential barriers, which may enable devices utilizing quantum confinement at room temperature. While a single heterointerface is easily formed by oxide deposition on a crystalline semiconductor, as in MOS transistors, the amorphous structure of most oxides inhibits epitaxy of a second semiconductor layer. Here, we overcome this limitation by separating epitaxy from oxidation, using postgrowth oxidation of AlP segments to create axial and core-shell semiconductor-oxide heterostructured nanowires. Complete epitaxial AlP-InP nanowire structures were first grown in an oxygen-free environment. Subsequent exposure to air converted the AlP segments into amorphous aluminum oxide segments, leaving isolated InP segments in an oxide matrix. InP quantum dots formed on the nanowire sidewalls exhibit room temperature photoluminescence with small line widths (down to 15 meV) and high intensity. This optical performance, together with the control of heterostructure segment length, diameter, and position, opens up for optoelectrical applications at room temperature. PMID:24195687

Wallentin, Jesper; Ek, Martin; Vainorious, Neimantas; Mergenthaler, Kilian; Samuelson, Lars; Pistol, Mats-Erik; Reine Wallenberg, L; Borgström, Magnus T

2013-12-11

435

The Oxidative Aging of Model Oxidized Organic Aerosol Systems  

NASA Astrophysics Data System (ADS)

Modeling and predictions of the behavior of highly oxidized organic aerosol components in the atmosphere often fall short in describing such systems, in part because of the difficulty of accessing appropriately high levels of oxidation (equivalent to one or two weeks in the atmosphere) in a laboratory setting. In this work, we present results from the heterogeneous oxidation by hydroxyl radicals (OH) of particles composed of pure citric, tartaric, or 1,2,3,4-butanetetracarboxylic acid, as well as a fulvic acid sample, in a flow tube reactor. The combination of highly oxidized reagent compounds and high concentrations of OH within the reactor allow us to access very high degrees of oxidation relative to previous studies. As OH exposure increases, an increase in carbon oxidation state and a decrease in overall carbon content are observed, consistent with reaction types in which carbon-carbon bonds are broken and molecules become volatilized. At very high exposure levels, however, changes in both oxidation state and carbon content begin to slow. This evolving recalcitrance of OA constituents suggests a framework to determine under what circumstances oxidative aging will strongly affect atmospheric particle evolution.

Kessler, S. H.; Daumit, K. E.; Nah, T.; Smith, J. D.; Worsnop, D. R.; Wilson, K. R.; Kroll, J. H.

2011-12-01

436

Operation of staged membrane oxidation reactor systems  

SciTech Connect

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

437

Strength of nonuniformly oxidized PGX graphite  

Microsoft Academic Search

Flexural and tensile tests were performed on PGX graphite oxidized to produce a steep surface oxidation gradient. Companion tensile specimens were oxidized under different conditions to produce uniform oxidation throughout the specimen, and their tensile strength and Young's modulus were measured. The flexural strength, flexural elastic modulus, and tensile strength were reduced much less by surface oxidation than by uniform

R. J. Price; L. A. Beavan

1981-01-01

438

Zinc oxide varistors and\\/or resistors  

Microsoft Academic Search

Varistors and\\/or resistors that includes 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

Arnold Jr. Wesley D; Walter D. Bond; Robert J. Lauf

1993-01-01

439

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

440

Peroxynitrite-mediated oxidative protein modifications  

Microsoft Academic Search

Proteins are targets of reactive species and detection of oxidatively modified proteins is often used as an index of oxidative stress. Peroxynitrite is a strong oxidant formed by reaction of nitric oxide with superoxide. Using fatty acid-free bovine serum albumin as a model we examined peroxynitrite-mediated protein modifications. The reaction of protein with peroxynitrite resulted in the oxidation of tryptophan

Harry Ischiropoulos; Abu B. Al-Mehdi

1995-01-01

441

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

442

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

443

Oxidative stress and gene regulation  

Microsoft Academic Search

Reactive oxygen species are produced by all aerobic cells and are widely believed to play a pivotal role in aging as well as a number of degenerative diseases. The consequences of the generation of oxidants in cells does not appear to be limited to promotion of deleterious effects. Alterations in oxidative metabolism have long been known to occur during differentiation

R. G Allen; Maria Tresini

2000-01-01

444

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

445

Summary of Nitrous Oxide Investigations.  

National Technical Information Service (NTIS)

The Air Force Weapons Laboratory (AFWL) proposes to use nitrous oxide (N2O) as an oxidizer in a combustion process for an airborne system. A number of problem areas were investigated by AFWL or by other organizations under contract to AFWL. This report su...

J. K. Cawthra M. Eisenstadt

1976-01-01

446

Detection of nitric oxide pollution  

NASA Technical Reports Server (NTRS)

Studies of absorption spectra enhancement of certain atomic and molecular species inserter in dye-laser cavities have indicated that nitric oxide can be determined at low concentrations. Absorption coefficient of small amounts of nitric oxide in intra-laser-cavity absorption cell containing helium is enhanced by more than two orders of magnitude.

Chackerian, C., Jr.; Weisbach, M. F.

1973-01-01

447

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

448

Oxidative Stress and Lung Function  

Microsoft Academic Search

It has been suggested that lung function can be altered by both free radical and oxidant exposure, while antioxidant vitamin intake is positively related to lung function. However, the information on the relation of blood levels of oxidants and antioxidants to lung function is sparse. Trie present cross-sectional study, conducted from September 1995 to May 1996, analyzes the association between

Holger J. Schiinemann; Paola Muti; Jo L Freudenheim; Donald Armstrong; Richard Browne; Robert A. Klocke; Maurizio Trevisan

449

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

450

Aluminium porous oxide for electrets  

Microsoft Academic Search

Summary form only given, as follows. Progress in functional electronics requires development of new electret materials exhibiting high electret characteristics and compatibility with electronic technology. A coupled anodic oxide-polymer is a prospective electret material. The proper choice of electrolyte composition and anodization regime yields porous oxide films with a geometry of regular pores. It has been shown that pore growth

V. I. Shershulsky; D. V. Yakovlev

1988-01-01

451

Preferential oxidation of diamond {111}  

Microsoft Academic Search

Measurements using TGA, SEM, Raman spectroscopy and XRD reveal that diamond oxidizes at around 750 K through oxygen impinging into the densely packed {111} planes throughout the course of the reaction. It is also found that diamond graphitizes under vacuum at about 1100 K without orientation preference, which also occurs under an Ar inert gas environment. The intriguing oxidation behaviour

Chang Q. Sun; H. Xie; W. Zhang; H. Ye; P. Hing

2000-01-01

452

Nitrogen Oxides in Tobacco Smoke  

Microsoft Academic Search

BECAUSE of their considerable pharmacological significance, the presence of nitrogen oxides in tobacco smoke has been the subject of a number of reports in the past few years1-4. In general, the choice of experimental techniques has been such that the relative amounts of the principal components, nitric oxide (NO) and nitrogen dioxide (NO2), in cigarette smoke have not been clearly

Vello Norman; Charles H. Keith

1965-01-01

453

Metal oxide nanowires gas sensors  

Microsoft Academic Search

Metal oxides are an attractive and heterogeneous class of materials covering the entire range from metals to semiconductors and insulators and almost all aspects of material science and physics in areas including superconductivity and magnetism. As far as chemical sensing is concerned it has been known, from more than five decades, that the electrical conductivity of metal oxides semiconductors varies

E. Comini

2008-01-01

454

OXIDATIVE STRESS AND SARCOMERIC PROTEINS  

PubMed Central

Oxidative stress accompanies a wide spectrum of clinically important cardiac disorders, including ischemia/reperfusion, diabetes, and hypertensive heart disease. While reactive oxygen species (ROS) can activate signaling pathways that contribute to ischemic preconditioning and cardioprotection, high levels of ROS induce structural modifications of the sarcomere that impact on pump function and the pathogenesis of heart failure. However, the precise nature of the redox-dependent change in contractility is determined by the source/identity of the oxidant species, the level of oxidative stress, and the chemistry/position of oxidant-induced post-translational modifications on individual proteins within the sarcomere. This review focuses on various ROS-induced post-translational modifications of myofilament proteins (including direct oxidative modifications of myofilament proteins, myofilament protein phosphorylation by ROS-activated signaling enzymes, and myofilament protein cleavage by ROS-activated proteases) that have been implicated in the control of cardiac contractility.

Steinberg, Susan F.