Sample records for heat-activated persulfate oxidation

  1. Effects of heat-activated persulfate oxidation on soil microorganisms.

    PubMed

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

    2008-02-01

    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

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

    PubMed

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

    2007-02-01

    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

  3. PCE oxidation by sodium persulfate in the presence of solids.

    PubMed

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

    2010-12-15

    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

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

    PubMed

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

    2014-01-15

    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

  5. Ultrasonically enhanced persulfate oxidation of polyethylene surfaces

    Microsoft Academic Search

    Fiona Keen

    1996-01-01

    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

  6. Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments

    Microsoft Academic Search

    Chiel Cuypers; Tim Grotenhuis; Jan Joziasse; Wim Rulkens

    2000-01-01

    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

  7. Rapid persulfate oxidation predicts PAH bioavailability in soils and sediments

    SciTech Connect

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

    2000-05-15

    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.

  8. Liquid-phase catalytic oxidation of CO by ammonium persulfate

    SciTech Connect

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

    1984-01-01

    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.

  9. Degradation of volatile organic compounds with thermally activated persulfate oxidation

    Microsoft Academic Search

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

    2005-01-01

    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

  10. Microwave-enhanced persulfate oxidation to treat mature landfill leachate.

    PubMed

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

    2015-03-01

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

  11. Evaluation of persulfate oxidative wet scrubber for removing BTEX gases.

    PubMed

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

    2009-05-30

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

  12. Transformation of bromide in thermo activated persulfate oxidation processes.

    PubMed

    Lu, Junhe; Wu, Jinwei; Ji, Yuefei; Kong, Deyang

    2015-07-01

    Sulfate radicals ( [Formula: see text] ) are applied to degrade various organic pollutants. Due to its high oxidative potential, [Formula: see text] is presumed to be able to transform bromide to reactive bromine species that can react with natural organic matter subsequently to form brominated products including brominated disinfection by-products (Br-DBPs). This research was designed to investigate the transformation of bromide in thermo activated persulfate oxidation process in the presence of humic acid (HA). Significant formation of bromoform and bromoacetic acids was verified. Their formation was attributed to the reactions of HA and reactive bromine species including Br·, [Formula: see text] HOBr(-), and free bromine resulted from the oxidation of bromide by [Formula: see text] . Yields of Br-DBPs increased monotonically at persulfate concentration of 1.0 mM and working temperature of 70 °C. However, the time-depended formation exhibited an increasing and the decreasing profile when persulfate was 5.0 mM, suggesting further degradation of organic bromine. HPLC/ICP-MS analysis demonstrated that the organic bromine was eventually transformed to bromate at this condition. Thus, a transformation scheme was proposed in which the bromine could be recycled multiple times between inorganic bromide and organic bromine before being finally transformed to bromate. This is the first study that reveals the comprehensive transformation map of bromine in [Formula: see text] based reaction systems, which should be taken into consideration when such technologies are used to eliminate contamination in real practice. PMID:25898247

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

    PubMed

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

    2015-04-15

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

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

    Microsoft Academic Search

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

    2008-01-01

    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

  15. Defluorination of aqueous perfluorooctanesulfonate by activated persulfate oxidation.

    PubMed

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

    2013-01-01

    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

  16. Defluorination of Aqueous Perfluorooctanesulfonate by Activated Persulfate Oxidation

    PubMed Central

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

    2013-01-01

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

  17. Activation of Persulfate by Iron Filings and Oxidation of 1,4-Dioxane

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhong, H.; Yan, N.; Brusseau, M. L.

    2014-12-01

    The use of iron filings to promote in-situ activation of persulfate for permeable reactive barrier systems is investigated with batch and column experiments. The application of the approach was illustrated for oxidation of 1,4-dioxane. The results of the batch experiments showed that in the absence of the iron filings both persulfate decomposition and dioxane degradation were slow, with pseudo first-order half-lives of 160 d-1 and 6.3 d-1, respectively. In the presence of the iron filings, persulfate decomposition and dioxane degradation was much faster, with reductions in concentrations of 86% and 34% in the first 30 minutes, respectively. Approximately 10% of the dioxane injected into a column packed with iron filings was degraded. Analysis of persulfate and sulfate concentrations in the column effluent produced balanced total sulfur. The rate coefficient obtained from the column experiments was similar to the value obtained from the batch experiments.

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

    PubMed

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

    2015-03-01

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

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

    PubMed Central

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

    2010-01-01

    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. PMID:21162560

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

    Microsoft Academic Search

    James H. McKenna; Peter H. Doering

    1995-01-01

    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

  1. 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 ...

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

    Microsoft Academic Search

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

    2000-01-01

    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

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

    Microsoft Academic Search

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

    2002-01-01

    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

  4. Effect of photoirradiation on potassium persulfate-surface oxidation of low-density polyethylene film

    Microsoft Academic Search

    Hitoshi Kubota; Yayoi Hariya; Shin-ichi Kuroda; Takashi Kondo

    2001-01-01

    Surface oxidation of low-density polyethylene (PE) film (thickness=30 ?m) with potassium persulfate (KPS) was investigated at 50°C in water. The surface oxidation was followed by ATR-IR measurement of the oxidized PE film, where the absorbance ratio of the carbonyl group at 1716 cm?1 to the methylene group at 1460 cm?1 was used as a measure of the oxidation. The absorbance

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

    PubMed

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

    2013-12-15

    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

  6. 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,...

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

    Microsoft Academic Search

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

    2007-01-01

    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

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

    Microsoft Academic Search

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

    2004-01-01

    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

  9. Strategy for identification and detection of multiple oxidative modifications within proteins applied on persulfate-oxidized hemoglobin and human serum albumin.

    PubMed

    Mörtstedt, Harriet; Jeppsson, Marina C; Ferrari, Giovanni; Jönsson, Bo A G; Kåredal, Monica H; Lindh, Christian H

    2011-01-30

    Oxidative stress has been suggested as an underlying mechanism of many human diseases. However, definitive evidence for this association has not been presented due to different shortcomings of the methods used to measure biomarkers of oxidative stress. Persulfates are oxidizing agents known to elicit hypersensitive reactions from the airways and skin. Despite a frequent use of persulfates at many work places, no biomarkers for persulfate exposure are available. The aim of this study was to develop a strategy for the identification and detection of multiple oxidative modifications within proteins. This strategy was applied on persulfate-oxidized proteins to identify oxidized peptides suitable for further investigation as biomarkers of persulfate exposure or oxidative stress. A strategy for the identification and the relative quantification of multiple oxidative modifications within proteins was developed. The usage of two software packages facilitated the search for modified peptides to a great extent. Oxidized peptides were relatively quantified using liquid chromatography/tandem mass spectrometry in selected reaction monitoring mode. The result showed that persulfates oxidize tryptophans and methionines resulting in mass shifts of 16 and/or 32 Da. Also, oxidized albumin peptides in nasal lavage fluid samples from subjects challenged with persulfate were detected. The oxidation degree before and after challenge remained constant for peptides containing methionine sulfoxide. For peptides containing oxidized tryptophan the oxidation degree increased after exposure. Some of these oxidized peptides may be suitable as biomarkers; however, further evaluation is required. PMID:21192028

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

    SciTech Connect

    Ermakov, V.A.

    1986-07-01

    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.

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

    Microsoft Academic Search

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

    2004-01-01

    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).

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

    PubMed

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

    2014-09-01

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

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

    PubMed

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

    2012-07-01

    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

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

    PubMed

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

    2013-06-01

    The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH3-N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m(3) ozone, 1g/1g COD0/S2O8(2-) ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH3-N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O3/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S2O8(2-) only, to evaluate its effectiveness. The combined method (i.e., O3/S2O8(2-)) achieved higher removal efficiencies for COD, color, and NH3-N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate. PMID:23498721

  15. The Persulfate Process for the Mediated Oxidation of Organic Pollutants

    NASA Astrophysics Data System (ADS)

    Vatistas, N.; Comninellis, Ch.

    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.

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

    NASA Astrophysics Data System (ADS)

    Hauswirth, S.; Miller, C. T.

    2013-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Wang, Tingmei

    2009-12-01

    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.

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

    PubMed

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

    2013-12-15

    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

  19. 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...

  20. Influence of Micelles of Different Types of Surfactant on the Mechanism of Diphenylamine Oxidation with Potassium Persulfate

    Microsoft Academic Search

    M. G. Gevorkyan

    2005-01-01

    Data on diphenylamine oxidation with potassium persulfate in aqueous-organic micellar solutions of different surfactants are generalized. The general effects of different surfactants are explained by the fact that different parts of micelles influence particular steps of multistep chemical reactions. This approach will enable one to control the formation rates of the intermediate or final product by making use of reaction

  1. Contaminated Groundwater Remediation by Catalyzed Hydrogen Peroxide and Persulfate Oxidants System

    NASA Astrophysics Data System (ADS)

    Yan, N.; Wang, Y.; Brusseau, M. L.

    2014-12-01

    A binary oxidant system, catalyzed hydrogen peroxide (H2O2) coupled with persulfate (S2O82-), was investigated for use in in-situ chemical oxidation (ISCO) applications. Trichloroethene (TCE) and 1,4-dioxane were used as target contaminants. Batch experiments were conducted to investigate the catalytic efficiency between ferrous ion (Fe2+) and base (NaOH), oxidant decomposition rates, and contaminant degradation efficiency. For the base-catalyzed H2O2-S2O82- system, oxidant release was moderate and sustained over the entire test period of 96 hours. Conversely, the oxidants were depleted within 24 hours for the Fe2+-catalyzed system. Solution pH decreased slightly for the Fe2+-catalyzed system, whereas the pH increased for the base-catalyzed system. The rates of degradation for TCE and 1,4-dioxane are compared as a function of system conditions. The results of this study indicate that the binary H2O2-S2O82- oxidant system is effective for oxidation of the tested contaminants.

  2. [Degradation of diuron by persulfate oxidation activated by EDTA-ferrous ion in aqueous system].

    PubMed

    Zhang, Jin-Feng; Yang, Xi; Zheng, Wei; Kong, Ling-Ren; Wang, Lian-Hong

    2008-05-01

    The method of diuron [3-(3,4-dichlorophenyl)-1, 1-dimethylurea] degradation by persulfate oxidation activated by EDTA-ferrous ion in aqueous system was conducted. Based on both of the degradation performance and the operating costs, optimal reaction condition was proposed. Operating at K2S2O8 initial concentration 2.0 mmol x L(-1), Fe(II) initial concentration 1.0 mmol x L(-1), EDTA initial concentration 0.5 mmol x L(-1), reaction time 300 min and pH = 7.0, about 67.6% of 0.1 mmol x L(1) diuron was degradation. Hydroxyl radicals and sulfate radicals produced in the system were determined by molecular probes (ethanol and tert-butanol) methods. The degradation products of diuron were identified with LC/MS methods and the degradation pathways of diuron were discussed. PMID:18624186

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

    Microsoft Academic Search

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

    2003-01-01

    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,

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

    Microsoft Academic Search

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

    2002-01-01

    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

  5. Persulfate activation by subsurface minerals

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    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.

  6. Studies on oxidative radiolysis of ibuprofen in presence of potassium persulfate

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    The radiolysis of ibuprofen (IBP), a model pharmaceutical compound, was studied by gamma irradiation in an aqueous solution in the presence and absence of potassium persulfate (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.

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

    Microsoft Academic Search

    SAM PINO; SHIH-LIEH FANG; E. BRAVERMAN

    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

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

    PubMed

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

    2014-04-01

    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

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

    Microsoft Academic Search

    M. M. Barbooti; F. Jasim

    1978-01-01

    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.

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

    PubMed

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

    2015-03-01

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

  11. Hg 0 absorption in potassium persulfate solution

    Microsoft Academic Search

    Qun-feng Ye; Cheng-yun Wang; Da-hui Wang; Guan Sun; Xin-hua Xu

    2006-01-01

    The aqueous phase oxidation of gaseous elemental mercury (Hg0) by potassium persulfate (KPS) catalyzed by Ag+ was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured\\u000a by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium\\u000a persulfate and silver nitrate (SN), temperature, Hg0 concentration

  12. Oxidation of 1,3-Dioxacyclanes with Oxone and Potassium Persulfate Catalyzed by 2,2,5,5-Tetramethyl-4Phenyl3Imidazoline3Oxide1-Oxyl

    Microsoft Academic Search

    Z. F. Akbalina; N. N. Kabalnova; S. S. Zlotsky; I. A. Grigoriev; V. V. Shereshovets; G. A. Tolstikov

    2001-01-01

    The catalytic effect of 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl on the oxidation of 2-isopropyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 2-phenyl-4-chlormethyl-1,3-dioxolane, 2-isopropyl-1,3-dioxane, 2-isopropyl-4-methyl-1,3-dioxane, 2-phenyl-1,3-dioxane, 2-phenyl-4-methyl-1,3-dioxane with oxone and potassium persulfate is reported. The corresponding glycol monoesters were obtained with yields of 90-100%.

  13. Fundamentals of ISCO Using Persulfate

    Microsoft Academic Search

    Benjamin G. Petri; Richard J. Watts; Aikaterini Tsitonaki; Michelle Crimi; Neil R. Thomson; Amy L. Teel

    \\u000a \\u000a Scope  Chemistry and use of persulfate for in situ chemical oxidation of subsurface contaminants, including free radical and other reaction mechanisms, catalysts, subsurface\\u000a transport, and contaminant treatability.\\u000a \\u000a \\u000a \\u000a \\u000a Key Concepts  \\u000a \\u000a \\u000a \\u000a \\u000a • \\u000a \\u000a \\u000a \\u000a Persulfate reaction chemistry is complex. Persulfate can react through direct electron transfer or free radical reactions.\\u000a Electron transfer reactions are relatively slow and selective. Upon activation, the free radicals generated have

  14. Persulfate activation by naturally occurring trace minerals.

    PubMed

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

    2011-11-30

    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

  15. 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...

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

    PubMed

    Ma, Jing-jing; Yi, Wen-bin; Lu, Guo-ping; Cai, Chun

    2015-03-14

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

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

    Microsoft Academic Search

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

    2004-01-01

    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

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

    PubMed

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

    2014-11-13

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

  19. Treatment of aqueous bisphenol A using nano-sized zero-valent iron in the presence of hydrogen peroxide and persulfate oxidants.

    PubMed

    Girit, B; Dursun, D; Olmez-Hanci, T; Arslan-Alaton, I

    2015-01-01

    Bisphenol A (BPA) is an industrial pollutant considered as one of the major endocrine-disrupting chemicals found in natural waters. In the present study, the use of a commercial, air-stable, zero-valent iron (ZVI) powder, consisting of Fe(0) surface stabilized nanoparticles was examined for the treatment of 20 mg/L, aqueous BPA solutions. The influence of pH (3, 5, 7), addition of hydrogen peroxide (HP) and persulfate (PS) oxidants (0.0, 1.25 and 2.5 mM) as well as temperature (25 and 50 °C) was studied for BPA treatment with 1 g/L ZVI. ZVI coupled with HP or PS provided an effective treatment system, which was based on rapid ZVI-mediated decomposition of the above-mentioned oxidants, resulting in complete BPA as well as significant total organic carbon (TOC) (88%) removals, in particular when PS was employed as the oxidant. Increasing the PS concentration and reaction temperature dramatically enhanced PS decomposition and BPA removal rates, whereas HP was not very effective in TOC removals and at elevated temperatures. According to the bioassays conducted with Vibrio fischeri and Pseudokirchneriella subcapitata, the acute toxicity of aqueous BPA fluctuated at first but decreased appreciably at the end of ZVI/PS treatment. PMID:26067507

  20. Persulfate injection into a gasoline source zone

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

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

    2014-12-01

    Persulfate-based in situ chemical oxidation (ISCO) is a promising technique for the remediation of organic compounds contaminated soils. Electrokinetics (EK) provides an alternative method to deliver oxidants into the target zones especially in low permeable-soil. In this study, the flexibility of delivering persulfate by EK to remediate polychlorinated biphenyls (PCBs) polluted soil was investigated. 20% (w/w) of persulfate was injected at the anode, cathode and both electrodes to examine its transport behaviors under electrical field, and the effect of field inversion process was also evaluated. The results showed that high dosage of persulfate could be delivered into S4 section (near cathode) by electroosmosis when persulfate was injected from anode, 30.8% of PCBs was removed from the soil, and the formed hydroxyl precipitation near the cathode during EK process impeded the transportation of persulfate. In contrast, only 18.9% of PCBs was removed with the injection of persulfate from cathode, although the breakthrough of persulfate into the anode reservoir was observed. These results indicated that the electroosmotic flow is more effective for the transportation of persulfate into soil. The addition of persulfate from both electrodes did not significantly facilitate the PCBs oxidation as well as the treatment of electrical field reversion, the reinforced negative depolarization function occurring in the cathode at high current consumed most of the oxidant. Furthermore, it was found that strong acid condition near the anode favored the oxidation of PCBs by persulfate and the degradation of PCBs was in consistent with the oxidation of Soil TOC in EK/persulfate system. PMID:25193794

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

    PubMed

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

    2012-04-28

    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

  3. Diversity-oriented synthesis of benzimidazole, benzoxazole, benzothiazole and quinazolin-4(3H)-one libraries via potassium persulfate–CuSO 4 -mediated oxidative coupling reactions of aldehydes in aqueous micelles

    Microsoft Academic Search

    Atul Kumar; Ram Awatar Maurya; Deepti Saxena

    2010-01-01

    Libraries of 2-substituted-benzimidazoles, benzoxazoles, benzothiazoles as well as quinazolin-4(3H)-ones were synthesized\\u000a via potassium persulfate–CuSO4-mediated oxidative coupling of aldehydes with o-phenylenediamines, o-aminophenols, o-aminothiophenols, and anthranilamide, respectively, in aqueous micelles. The strategy opens a way for rapid generation of\\u000a libraries of small heterocycles for biological screening. The reagent is commercially available, cheap, and highly chemoselective.\\u000a The yields were superior in aqueous micelles

  4. 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...

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

    PubMed

    Chen, Wen-Shing; Huang, Chi-Pin

    2015-04-01

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

  6. Sonochemical acceleration of persulfate decomposition

    Microsoft Academic Search

    Gareth J. Price; Andrew A. Clifton

    1996-01-01

    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

  7. Potential for activated persulfate degradation of BTEX contamination

    Microsoft Academic Search

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

    2008-01-01

    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

  8. Gold cyanidation with potassium persulfate in the presence of a thallium (I) salt

    Microsoft Academic Search

    L Guzman; J. M Chimenos; M. A Fernandez; M Segarra; F Espiell

    2000-01-01

    The use of potassium persulfate as oxidant in gold cyanidation is proposed at pH values between 10 and 11. The addition of thallium (I) ions enables high cyanidation rates to be maintained at pH values higher than 11, as it acts as a catalyst of the process. When gold cyanidation is performed in the simultaneous presence of 10 mM persulfate

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

    SciTech Connect

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

    1994-06-01

    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.

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

    Microsoft Academic Search

    Rajender S Varma; Harshadas M Meshram

    1997-01-01

    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.

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

    PubMed

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

    2015-02-01

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

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

    PubMed

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

    2014-01-01

    Activated persulfate oxidation is an effective in situ chemical oxidation process for groundwater remediation. However, reactivity of persulfate is difficult to manipulate or control in the subsurface causing activation before reaching the contaminated zone and leading to a loss of chemicals. Furthermore, mobilization of heavy metals by the process is a potential risk. An effective approach using iron electrodes is thus developed to manipulate the reactivity of persulfate in situ for trichloroethylene (TCE) degradation in groundwater and to limit heavy metals mobilization. TCE degradation is quantitatively accelerated or inhibited by adjusting the current applied to the iron electrode, following k1 = 0.00053·Iv + 0.059 (-122 A/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

  13. Dual anticoagulant/antiplatelet persulfated small molecules.

    PubMed

    Correia-da-Silva, Marta; Sousa, Emília; Duarte, Bárbara; Marques, Franklim; Cunha-Ribeiro, Luís M; Pinto, Madalena M M

    2011-06-01

    A new series of persulfated compounds was synthesized and assayed for in vitro anticoagulant and antiplatelet activities, which may be useful in the treatment of both venous and arterial thrombosis. Persulfation of polyphenolic components of wine, coumarins and other structurally diverse small molecules was achieved with triethylamine-sulphur trioxide adduct. The derivatives were highly effective in increasing the APTT, being trans-resveratrol 3-ß-D-glucopyranoside persulfate (15) the most potent (APTT2=1.5×10(-4) M), and were able to completely block the clotting process at the highest concentration. Compound 15 showed good stability in human plasma and anticoagulation effects in whole blood. trans-Resveratrol 3-ß-D-glucopyranoside persulfate (15) and a series of polysulfated oligoflavonoids (1-4) also exhibited antiplatelet activity by inhibition of arachidonic acid and ADP-induced platelet aggregation. PMID:21450376

  14. Electrolysis cell for the manufacture of persulfates

    NASA Technical Reports Server (NTRS)

    Cueto, J. M.

    1986-01-01

    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.

  15. 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 Central

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

    2013-01-01

    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·. PMID:24790933

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  17. Leaching of Calcareous Bornite Ore in Ammoniacal Solution Containing Ammonium Persulfate

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2012-12-01

    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

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

    PubMed

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

    2015-06-01

    Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel conditioning method for improving waste activated sludge dewaterability by combination of persulfate and zero-valent iron. The combination of zero-valent iron (0-30g/L) and persulfate (0-6g/L) under neutral pH substantially enhanced the sludge dewaterability due to the advanced oxidization reactions. The highest enhancement of sludge dewaterability was achieved at 4g persulfate/L and 15g zero-valent iron/L, with which the capillary suction time was reduced by over 50%. The release of soluble chemical oxygen demand during the conditioning process implied the decomposition of sludge structure and microorganisms, which facilitated the improvement of dewaterability due to the release of bound water that was included in sludge structure and microorganism. Economic analysis showed that the proposed conditioning process with persulfate and ZVI is more economically favorable for improving WAS dewaterability than classical Fenton reagent. PMID:25804531

  1. 75 FR 2112 - Persulfates From the People's Republic of China: Notice of Rescission of the 2008-2009...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ...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...

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

    Microsoft Academic Search

    Yeong Suk Choi; Hyeong Taek Ham; In Jae Chung

    2003-01-01

    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

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

    PubMed

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

    2012-09-25

    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

  4. 78 FR 14591 - Persulfates From China; Correction to Notice of institution

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ...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....

  5. Determination of Attogram Quantities of Silver via Quenching of the Solid Substrate Room-Temperature Phosphorescence of Rhodamine B Based on the Catalysis of its Oxidation by Potassium Persulfate

    Microsoft Academic Search

    Jia-Ming Liu; Xuan Lin; Chang-Jin Wei; Long-Di Li

    2004-01-01

    A new method of SS-RTP for the determination of trace silver has been established. This method is based on the fact that Ag +, when activated by ?,??-bipyridyl (bipy) in a media of HAc–NaAc (pH?=?4.9), can catalyze the reaction of Rhodamine B (RhoB) oxidized by K 2S 2O 8, thus causing the Solid Substrate Room-Temperature Phosphorescence (SS-RTP) of RhoB to

  6. Transformation of [M+2H](2+) Peptide Cations to [M - H] (+), [M+H+O] (+), and M (+•) Cations via Ion/Ion Reactions: Reagent Anions Derived from Persulfate.

    PubMed

    Pilo, Alice L; Bu, Jiexun; McLuckey, Scott A

    2015-07-01

    The gas-phase oxidation of doubly protonated peptides is demonstrated here using ion/ion reactions with a suite of reagents derived from persulfate. Intact persulfate anion (HS2O8 (-)), peroxymonosulfate anion (HSO5 (-)), and sulfate radical anion (SO4 (-•)) are all either observed directly upon negative nanoelectrospray ionization (nESI) or easily obtained via beam-type collisional activation of persulfate into the mass spectrometer. Ion/ion reactions between each of these reagents and doubly protonated peptides result in the formation of a long-lived complex. Collisional activation of the complex containing a peroxymonosulfate anion results in oxygen transfer from the reagent to the peptide to generate the [M+H+O](+) species. Activation of the complex containing intact persulfate anion either results in oxygen transfer to generate the [M+H+O](+) species or abstraction of two hydrogen atoms and a proton to generate the [M - H](+) species. Activation of the complex containing sulfate radical anion results in abstraction of one hydrogen atom and a proton to form the peptide radical cation, [M](+•). This suite of reagents allows for the facile transformation of the multiply protonated peptides obtained via nESI into a variety of oxidized species capable of providing complementary information about the sequence and structure of the peptide. Graphical Abstract ?. PMID:25944366

  7. Free radical degradation of chitosan with potassium persulfate

    Microsoft Academic Search

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

    2002-01-01

    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.

  8. Cocatalyst effect in potassium persulfate initiated grafting onto chitosan

    Microsoft Academic Search

    J. Retuert; M. Yazdani-Pedram

    1993-01-01

    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.

  9. Determination of an Effective Perfluorinated Compounds (PFCs) Oxidation Method

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    Microsoft Academic Search

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

    2000-01-01

    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

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

    SciTech Connect

    Berlin, A.A

    1986-07-01

    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.

  13. 78 FR 64244 - Persulfates From China; Revised Schedule for the Subject Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-28

    ...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....

  14. Activation of persulfate by irradiated magnetite: implications for the degradation of phenol under heterogeneous photo-Fenton-like conditions.

    PubMed

    Avetta, Paola; Pensato, Alessia; Minella, Marco; Malandrino, Mery; Maurino, Valter; Minero, Claudio; Hanna, Khalil; Vione, Davide

    2015-01-20

    We show that phenol can be effectively degraded by magnetite in the presence of persulfate (S2O8(2–)) under UVA irradiation. The process involves the radical SO4(–•), formed from S2O8(2–) in the presence of Fe(II). Although magnetite naturally contains Fe(II), the air-exposed oxide surface is fully oxidized to Fe(III) and irradiation is required to produce Fe(II). The magnetite + S2O8(2–) system was superior to the corresponding magnetite + H2O2 one in the presence of radical scavengers and in a natural water matrix, but it induced phenol mineralization in ultrapure water to a lesser extent. The leaching of Fe from the oxide surface was very limited, and much below the wastewater discharge limits. The reasonable performance of the magnetite/persulfate system in a natural water matrix and the low levels of dissolved Fe are potentially important for the removal of organic contaminants in wastewater. PMID:25535799

  15. 78 FR 35314 - Persulfates From China; Notice of Commission Determination To Conduct a Full Five-Year Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-12

    ...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...

  16. 78 FR 40695 - Persulfates From the People's Republic of China: Final Results of Expedited Third Sunset Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-08

    ...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...

  17. 78 FR 52969 - Persulfates From China; Scheduling of a Full Five-Year Review Concerning the Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-27

    ...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...

  18. 76 FR 13358 - Persulfates From the People's Republic of China: Preliminary Results of the 2009-2010 Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-11

    ...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,...

  19. 76 FR 35402 - Persulfates From the People's Republic of China: Notice of Correction to the Final Results of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-17

    ...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...

  20. 78 FR 13891 - Persulfates From China; Institution of a Five-Year Review Concerning the Antidumping Duty Order...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ...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...

  1. 76 FR 28419 - Persulfates From the People's Republic of China: Final Results of the 2009-2010 Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ...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...

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

    PubMed

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

    2015-04-01

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

  3. Degradation and dechlorination of pentachlorophenol by microwave-activated persulfate.

    PubMed

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

    2015-03-01

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

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

    PubMed

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

    2015-04-01

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

  5. Some supplementary data on particular features of the thermal behaviour of potassium persulfate

    Microsoft Academic Search

    V. M. Gorbachev; F. R. Verzhbitsky; K. G. Myakishev; O. G. Potapova

    1984-01-01

    The effects of preliminary mechanical activation and thermal treatment of potassium persulfate on the thermal and electrical characteristics of its thermal decomposition were studied by DTA, TG, evolved gas volumetry and high-frequency thermal analysis.

  6. Silver-catalyzed PuO sub 2 dissolution with persulfate

    SciTech Connect

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

    1991-06-01

    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)

  7. Rapid and simple spectrophotometric determination of persulfate in water by microwave assisted decolorization of Methylene Blue.

    PubMed

    Zhao, Lajuan; Yang, Shiying; Wang, Leilei; Shi, Chao; Huo, Meiqing; Li, Yan

    2015-05-01

    A rapid and simple method for determination of persulfate in aqueous solution was developed. The method is based on the rapid reaction of persulfate with Methylene Blue (MB) via domestic microwave activation, which can promote the activation of persulfate and decolorize MB quickly. The depletion of MB at 644nm (the maximum absorption wavelength of MB) is in proportion to the increasing concentration of persulfate in aqueous solution. Linear calibration curve was obtained in the range 0-1.5mmol/L, with a limit of detection of 0.0028mmol/L. The reaction time is rapid (within 60sec), which is much shorter than that used for conventional methods. Compared with existing analytical methods, it need not any additives, especially colorful Fe(2+), and need not any pretreatment for samples, such as pH adjustment. PMID:25968279

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

    E-print Network

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Manipulation of persistent free radicals in biochar to activate persulfate for contaminant degradation.

    PubMed

    Fang, Guodong; Liu, Cun; Gao, Juan; Dionysiou, Dionysios D; Zhou, Dongmei

    2015-05-01

    This study investigated the effects of metals (Fe(3+), Cu(2+), Ni(2+), and Zn(2+)) and phenolic compounds (PCs: hydroquinone, catechol, and phenol) loaded on biomass on the formation of persistent free radicals (PFRs) in biochar. It was found that metal and phenolic compound treatments not only increased the concentrations of PFRs in biochar but also changed the types of PFRs formed, which indicated that manipulating the amount of metals and PCs in biomass may be an efficient method to regulate PFRs in biochar. These results provided direct evidence to elucidate the mechanism of PFR formation in biochar. Furthermore, the catalytic ability of biochar toward persulfate activation for the degradation of contaminants was evaluated. The results indicated that biochar activates persulfate to produce sulfate radicals (SO4(•-)) and degraded polychlorinated biphenyls (PCBs) efficiently. It was found that both the concentration and type of PFRs were the dominant factors controlling the activation of persulfate by biochar and that superoxide radical anions account for 20-30% of sulfate radical generation in biochar/persulfate. This conclusion was supported by linear correlations between the concentration of PFRs consumed and the formation of SO4(•-) and between ? (? = [formed sulfate radicals]/[consumed PFRs]) and g-factors. The findings of this study provide new methods to manipulate PFR concentration in biochar for the transformation of contaminants and development of new alternative activators for persulfate-based remediation of contaminated soils. PMID:25864382

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

    PubMed

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

    2011-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    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.

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

    SciTech Connect

    Wiltsee, G.

    1994-02-01

    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.

  14. Radical Polymerization of Maleic Acid by Potassium Persulfate in the Presence of Polyvinylpyrrolidone in Water

    Microsoft Academic Search

    Tsuneyuki Sato; Kazuhiko Nemoto; Shigeki Mori; Takayuki Otsu

    1979-01-01

    Maleic acid(MA) was found to polymerize easily by potassium persulfate (KPS) in water in the presence of polyvinylpyrrolidone (PVP), and to form a polymer complex in which the molar ratio of MA to VP monomer unit was approximately unity. The formation of the polymer complex was accelerated by increases in the reaction temperature, in the concentrations of KPS and MA,

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

    Microsoft Academic Search

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

    1985-01-01

    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.

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

    PubMed

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

    2014-10-25

    Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. PMID:25459832

  17. Oxidation of Aromatic Aldehydes Using Oxone

    ERIC Educational Resources Information Center

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

    2007-01-01

    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…

  18. 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

    Craig, D.; Holditch, S.A.

    1993-12-01

    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.

  19. Photodegradation of perfluorooctanoic acid in water under irradiation of 254 nm and 185 nm light by use of persulfate.

    PubMed

    Chen, J; Zhang, P

    2006-01-01

    The photodegradation of perfluorooctanoic acid (PFOA) in water using two types of low-pressure mercury lamps, one emitting 254 nm and the other emitting 254 nm and 185 nm, by use of persulfate (K2S2O8) as an oxidant was investigated. PFOA was significantly decomposed under irradiation of 185 nm light, while it was very slow and negligible under 254 nm light irradiation. This was due to its strong absorption of PFOA from deep UV-region to 220 nm and a weak absorption from 220-460 nm. The addition of K2S2O8 led to efficient PFOA decomposition and defluorination no matter what light irradiation. Sulfate radical anion (SO4-), generated by photolysis of K2S2O8, initiated the oxidation of PFOA. Under irradiation of 185 nm light, PFOA was jointly decomposed through 185 nm light photolysis and initiation of sulfate radical. However, under irradiation of 254 nm light, PFOA decomposition was only initiated by sulfate radical. PFOA decomposed and defluorinated much faster under oxygen atmosphere than under nitrogen atmosphere, which suggested that oxygen molecules played an important role in PFOA decomposition. PMID:17302335

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  1. Plutonium oxide dissolution

    SciTech Connect

    Gray, J.H.

    1992-09-30

    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.

  2. Plutonium oxide dissolution

    SciTech Connect

    Gray, J.H.

    1992-09-30

    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.

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

    PubMed

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

    2014-12-16

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

  4. Paramagnetic centers in products of the mechanical treatment of potassium persulfate

    Microsoft Academic Search

    V. A. Radstig; A. A. Politov

    1985-01-01

    It was shown that the mechanical breakdown of potassium persulfate at 77°K is accompanied by the formation of paramagnetic centers of the types of SOâ⁻, SOâ⁻, and radical pairs. It was established that heating a mechanically activated sample to 375°K leads to an increase in the concentration of paramagnetic centers by more than an order of magnitude. This process is

  5. Kinetics of acrylamide solution polymerization using potassium persulfate as an initiator by in situ IR

    Microsoft Academic Search

    Shin Choon Kang; Yoo Jeong Choi; Hyung Zip Kim; Jin Burm Kyong; Dong Kook Kim

    2004-01-01

    We have studied the polymerization kinetics of acrylamide in aqueous solution with potassium persulfate as an initiator by\\u000a using quantitative real-timein situ IR spectroscopy and monitoring the profiles of peaks in the range 1900–850 cm?1. The conversion of acrylamide was calculated from the disappearance of the peak at 988 cm?1, which is the out-of-plane bending mode of the =C?H unit,

  6. Effect of surface treatment with potassium persulfate on dispersion stability of multi-walled carbon nanotubes

    Microsoft Academic Search

    Ok-kyung Park; Nam Hoon Kim; Kin-tak Lau; Joong Hee Lee

    2010-01-01

    Muti-walled carbon nanotubes (MWCNTs) were treated with different concentrations of potassium persulfate (KPS; K2S2O8) to improve their dispersion stability, which were characterized by thermal gravimetric analysis, ultraviolet\\/visible spectroscopy, field emission scanning electron microscopy and field emission transmission electron microscopy. The amount of sulfate groups on the MWCNTs increased with increasing KPS concentration, which enhanced the hydrophilicity, but deteriorated the dispersion

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

    Microsoft Academic Search

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

    2003-01-01

    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

  8. Time-dependent proteomic iTRAQ analysis of nasal lavage of hairdressers challenged by persulfate.

    PubMed

    Kåredal, Monica H; Mortstedt, Harriet; Jeppsson, Marina C; Kronholm Diab, Kerstin; Nielsen, Jørn; Jonsson, Bo A G; Lindh, Christian H

    2010-11-01

    Hairdressers are frequently exposed to bleaching powder containing persulfates, a group of compounds that may induce hypersensitivity in the airways. The mechanism causing this reaction is not clear. The aim of this study was to identify changes in the nasal lavage fluid proteome after challenge with potassium persulfate in hairdressers with bleaching powder-associated rhinitis. Furthermore, we aimed to compare their response to that of hairdressers without nasal symptoms, and atopic subjects with pollen-associated nasal symptoms. To study the pathogenesis of persulfate-associated rhinitis, the response in protein expression from the upper airway was assessed by time-dependent proteomic expression analysis of nasal lavage fluids. Samples were prepared by pooling nasal lavage fluids from the groups at different time points after challenge. Samples were depleted of high-abundant proteins, labeled with iTRAQ and analyzed by online 2D-nanoLC-MS/MS. Differences in the protein pattern between the three groups were observed. Most proteins with differentially expressed levels were involved in pathways of lipid transportation and antimicrobial activities. The major finding was increased abundance of apolipoprotein A-1, 20 min postchallenge, detected solely in the group of symptomatic hairdressers. Our results suggest there may be differences between the mechanisms responsible for the rhinitis in the symptomatic and atopic group. PMID:20815409

  9. Paramagnetic centers in products of the mechanical treatment of potassium persulfate

    SciTech Connect

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

    1985-07-01

    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.

  10. Homogeneous Catalysis Selective Oxidation of Methane to Methanol

    E-print Network

    Goddard III, William A.

    formed when SO3 or persulfate (K2S2O8) were added as possible oxidants of metallic gold (entries 5 and 6 oxidizing agent than SVI ions (Eo = 1.5 V SeO4 2Ã? /H2SeO3, Eo = 0.17 V SO4 2Ã? /H2SO3, respec- tively) and

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

    PubMed

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

    2015-02-01

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

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

    Microsoft Academic Search

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

    2000-01-01

    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

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

    PubMed

    Liu, Yangxian; Wang, Qian

    2014-10-21

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

  14. Flow injection amperometric determination of persulfate in cosmetic products using a Prussian Blue film-modified electrode

    Microsoft Academic Search

    Marcelo F. De Oliveira; Adelir A. Saczk; Jose A. Gomes Neto; Paulo S. Roldan

    2003-01-01

    A flow-injection system with a glassy carbon disk electrode modified with Prussian Blue film is proposed for the determination of persulfate in commercial samples of hair bleaching boosters by amperometry. The detection was obtained by chronoamperometric technique and the sample is injected into the electrochemical cell in a wall jet configuration. Potassium chloride at concentration of 0.1 mol L -1

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

    Microsoft Academic Search

    V. F. Kurenkov; T. A. Baiburdov; L. L. Stupenkova

    1988-01-01

    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.

  16. Friedel-Crafts Amidoalkylation via Thermolysis and Oxidative Photocatalysis

    PubMed Central

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

    2012-01-01

    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. PMID:22458307

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

    Microsoft Academic Search

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

    1994-01-01

    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

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

    Microsoft Academic Search

    S. E Cornell; T. D Jickells

    1999-01-01

    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

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

    SciTech Connect

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

    1985-10-01

    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/.

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

    PubMed Central

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

    2014-01-01

    Introduction Since persulfate salts are an important cause of occupational asthma (OA), we aimed to study the persistence of respiratory symptoms after a single exposure to ammonium persulfate (AP) in AP-sensitized mice. Material and Methods BALB/c mice received dermal applications of AP or dimethylsulfoxide (DMSO) on days 1 and 8. On day 15, they received a single nasal instillation of AP or saline. Airway hyperresponsiveness (AHR) was assessed using methacholine provocation, while pulmonary inflammation was evaluated in bronchoalveolar lavage (BAL), and total serum immunoglobulin E (IgE), IgG1 and IgG2a were measured in blood at 1, 4, 8, 24 hours and 4, 8, 15 days after the single exposure to the causal agent. Histological studies of lungs were assessed. Results AP-treated mice showed a sustained increase in AHR, lasting up to 4 days after the challenge. There was a significant increase in the percentage of neutrophils 8 hours after the challenge, which persisted for 24 hours in AP-treated mice. The extent of airway inflammation was also seen in the histological analysis of the lungs from challenged mice. Slight increases in total serum IgE 4 days after the challenge were found, while IgG gradually increased further 4 to 15 days after the AP challenge in AP-sensitized mice. Conclusions In AP-sensitized mice, an Ig-independent response is induced after AP challenge. AHR appears immediately, but airway neutrophil inflammation appears later. This response decreases in time; at early stages only respiratory and inflammatory responses decrease, but later on immunological response decreases as well. PMID:25303285

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

    PubMed

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

    2014-10-01

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

  2. Reaction analysis of 3,4-ethylenedioxythiophene with potassium persulfate in aqueous solution by using a calorimeter

    Microsoft Academic Search

    K. I. Seo; I. J. Chung

    2000-01-01

    A calorimeter was used to directly monitor the rate of emulsion polymerization of 3,4-ethylenedioxythiophene (EDOT) in aqueous solution for different concentrations of the initiator, potassium persulfate (KPS). The reaction involved polymerization and doping in one step, and yielded a poly(3,4-ethylenedioxythiophene) (PEDOT) with electrical conductivity. The electrical conductivity and yield of PEDOT increased as the molar ratio of KPS to EDOT

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

    Microsoft Academic Search

    Hong-Ru Lin

    2001-01-01

    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

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

    PubMed

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

    2007-01-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  6. A study on microwave oxidation of landfill leachate--contributions of microwave-specific effects.

    PubMed

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

    2013-02-15

    Microwave oxidation process (MOP) was evaluated for treatment of landfill leachate. The experimental parameters include pH, temperature, oxidant doses, microwave power setting, and irradiation time. The study explored the microwave-specific effects of the MOP. The contributions of pure thermal, persulfate oxidation and microwave irradiation on TOC removal were quantified. It was then found the combinations of them were usually synergistic in MOP except two of them were antagonistic (128 W/85°C/1M Na(2)S(2)O(8) and 128 W/85°C/2M Na(2)S(2)O(8)). At the highest temperature tested (85°C) in this study, microwave irradiation may cause generation and termination of oxidizing radicals at adverse rates. The study also found that persulfate decayed rapidly in either MOP or conventional heating oxidation (CHO) treatment of landfill leachate. PMID:23287411

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

    SciTech Connect

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

    1989-01-01

    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.

  8. 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...

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

    PubMed

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

    2013-11-01

    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

  10. Graft Copolymerization of Poly(methyl Methacrylate) onto Wool by the Potassium Persulfate-Thiomalic Acid Redox Couple in the Presence of Atmospheric Oxygen. Part I

    Microsoft Academic Search

    J. S. Shukla; G. K. Sharma; R. K. Tewari; S. K. Shukla

    1984-01-01

    The graft copolymerization of poly (methyl methacrylate) [PMMA] onto wool initiated by the potassium persulfate-thiomalic acid (TMA) redox couple has been investigated in the presence of atmospheric oxygen. The percentage of grafting efficiency and polymerization as a function of initiator, activator, monomer, temperature, time, and wool was estimated. Evidence of grafting was confirmed by IR spectroscopy. It was observed that

  11. The acceleration of decomposition of potassium persulfate in the presence of sodium dodecyl sulfate and polymer particles as a model of emulsion polymerization system

    Microsoft Academic Search

    M. Okubo; M. Fujimura; T. Mori

    1991-01-01

    The decomposition rates of potassium persulfate (KPS) in aqueous solutions containing sodium dodecyl sulfate (SDS) in the presence of polystyrene or poly(methyl methacrylate) particles as models of emulsion polymerization systems were measured by isotachophoresis. “Free” SDS molecules dispersed in the monomolecular state had an ability to accelerate the KPS decomposition, but SDS molecules adsorbed onto the polymer particles did not

  12. 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

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

    1987-02-01

    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.

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

    PubMed

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

    2015-01-01

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

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

    Microsoft Academic Search

    Josefina Vergara Sánchez; Susana Silva Martínez; Maria del Refugio Trejo Hernández

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

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

    Microsoft Academic Search

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

    2001-01-01

    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

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

    SciTech Connect

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

    1988-04-10

    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.

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

    PubMed

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

    2014-11-21

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

  18. Hg 0 oxidative absorption by K 2S 2O 8 solution catalyzed by Ag + and Cu 2+

    Microsoft Academic Search

    Xinhua Xu; Qunfeng Ye; Tingmei Tang; Dahui Wang

    2008-01-01

    The aqueous phase oxidation of gaseous elemental mercury (Hg0) by potassium persulfate (K2S2O8, KPS) catalyzed by Ag+ and Cu2+ was investigated using a glass bubble column reactor. Concentrations of gaseous Hg0 and aqueous Hg2+ were measured by cold vapor generation atomic absorption spectrometry (CVAAS). The effects of several experimental parameters on the oxidation were studied; these include different types of

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

    E-print Network

    US Army Corps of Engineers

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

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

    Microsoft Academic Search

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

    2001-01-01

    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.

  1. Derivative mechanisms of organic acids in microwave oxidation of landfill leachate.

    PubMed

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

    2013-06-15

    This study compared formation and degradation behaviors of organic acids in landfill leachate under microwave oxidation process (MOP) and under conventional heating oxidation (CHO) and explored derivative mechanisms of organic acids in MOP. The results showed that formation and degradation behaviors of oxalic acid were very similar under CHO and MOP, in which its concentrations decreased in the temperature-raising period, then increased due to decomposition of TOC from 10 to 70 min, decreased due to persulfate oxidation from 70 to 130 min, and stayed the same afterwards. The pH values of the leachate solution dropped 0.51 and 0.65 pH units after MOP and CHO treatment, respectively. Oxalic acid was the dominant organic acid formed in MOP. The derivative mechanisms of organic acids were developed using the experimental results. Lactic acid was generated from decomposition of malic acid, and oxalic acid was formed from oxidation of its precursors. Acetic acid was formed and soon decomposed. Lactic acid had its maximum concentration with a persulfate dose of 0.5M, while lower or higher persulfate doses yielded few or no lactic acid in MOP. PMID:23643953

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

    PubMed

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

    2011-03-01

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

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

    SciTech Connect

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

    2004-01-23

    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.

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

    Microsoft Academic Search

    Michelle L. Crimi; Jesse Taylor

    2007-01-01

    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

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

    SciTech Connect

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

    1986-09-01

    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.

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

    SciTech Connect

    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

    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.

  7. 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

    Patton, Charles J.; Kryskalla, Jennifer R.

    2003-01-01

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

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

    Microsoft Academic Search

    Justine Criquet; Nathalie Karpel Vel Leitner

    2009-01-01

    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

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

    Microsoft Academic Search

    Masaaki Hosomi; Ryuichi Sudo

    1986-01-01

    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

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

    Microsoft Academic Search

    George P. Anipsitakis; Dionysios D. Dionysiou

    2004-01-01

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

  11. Catalytic Decomposition of Organic Anions in Alkaline Radioactive Waste: 1. EDTA Oxidation

    Microsoft Academic Search

    A. Yu. Garnov; A. V. Gogolev; V. P. Shilov; L. N. Astafurova; N. N. Krot

    2002-01-01

    Decomposition of ethylenediaminetetraacetate in alkaline solutions with H2O2, Na2S2O8, NaClO, and NaBrO was studied titrimetrically. EDTA is oxidized in solutions heated above 60°C in the presence of cobalt salts at stepwise addition of excess H2O2. The reaction between persulfate and EDTA has an induction period decreasing with increasing NaOH concentration and temperature and with decreasing initial EDTA content or with

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

    PubMed

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

    2014-10-01

    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

  13. 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

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

    2012-01-01

    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

  14. 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

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

    2012-01-01

    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

  15. Pore region of TRPV3 ion channel is specifically required for heat activation.

    PubMed

    Grandl, Jörg; Hu, Hongzhen; Bandell, Michael; Bursulaya, Badry; Schmidt, Manuela; Petrus, Matt; Patapoutian, Ardem

    2008-09-01

    Ion channels can be activated (gated) by a variety of stimuli, including chemicals, voltage, mechanical force or temperature. Although molecular mechanisms of ion channel gating by chemical and voltage stimuli are understood in principal, the mechanisms of temperature activation remain unknown. The transient receptor potential channel TRPV3 is a nonselective cation channel that is activated by warm temperatures and sensory chemicals such as camphor. Here we screened approcimately 14,000 random mutant clones of mouse TRPV3 and identified five single point mutations that specifically abolish heat activation but do not perturb chemical activation or voltage modulation. Notably, all five mutations are located in the putative sixth transmembrane helix and the adjacent extracellular loop in the pore region of mouse TRPV3. Although distinct in sequence, we found that the corresponding loop of frog TRPV3 is also specifically required for heat activation. These findings demonstrate that the temperature sensitivity of TRPV3 is separable from all other known activation mechanisms and implicate a specific region in temperature sensing. PMID:19160498

  16. Degradation and mineralization of Bisphenol A (BPA) in aqueous solution using advanced oxidation processes: UV/H2O2 and UV/S2O8(2-) oxidation systems.

    PubMed

    Sharma, Jyoti; Mishra, I M; Kumar, Vineet

    2015-06-01

    This work reports on the removal and mineralization of an endocrine disrupting chemical, Bisphenol A (BPA) at a concentration of 0.22 mM in aqueous solution using inorganic oxidants (hydrogen peroxide, H2O2 and sodium persulfate, Na2S2O8;S2O8(2-)) under UV irradiation at a wavelength of 254 nm and 40 W power (Io = 1.26 × 10(-6) E s(-1)) at its natural pH and a temperature of 29 ± 3 °C. With an optimum persulfate concentration of 1.26 mM, the UV/S2O8(2-) process resulted in ?95% BPA removal after 240 min of irradiation. The optimum BPA removal was found to be ?85% with a H2O2 concentration of 11.76 mM. At higher concentrations, either of the oxidants showed an adverse effect because of the quenching of the hydroxyl or sulfate radicals in the BPA solution. The sulfate-based oxidation process could be used over a wider initial pH range of 3-12, but the hydroxyl radical-based oxidation of BPA should be carried out in the acidic pH range only. The water matrix components (bicarbonate, chloride and humic acid) showed higher scavenging effect in hydroxyl radical-based oxidation than that in the sulfate radical-based oxidation of BPA. UV/S2O8(2-) oxidation system utilized less energy (307 kWh/m(3)) EE/O in comparison to UV/H2O2 system (509 kWh/m(3)) under optimum operating conditions. The cost of UV irradiation far outweighed the cost of the oxidants in the process. However, the total cost of treatment of persulfate-based system was much lower than that of H2O2-based oxidation system. PMID:25889275

  17. 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

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

    1990-08-01

    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.

  18. Nitrogen-Doped Reduced Graphene Oxide as a Bifunctional Material for Removing Bisphenols: Synergistic Effect between Adsorption and Catalysis.

    PubMed

    Wang, Xiaobo; Qin, Yanlei; Zhu, Lihua; Tang, Heqing

    2015-06-01

    Nitrogen modified reduced graphene oxide (N-RGO) was prepared by a hydrothermal method. The nitrogen modification enhanced its adsorption and catalysis ability. For an initial bisphenol concentration of 0.385 mmol L(-1), the adsorption capacity of N-RGO was evaluated as 1.56 and 1.43 mmol g(-1) for bisphenol A (BPA) and 1.43 mmol g(-1) for bisphenol F (BPF), respectively, both of which were about 1.75 times that (0.90 and 0.84 mmol g(-1)) on N-free RGO. N-RGO could activate persulfate, producing strong oxidizing sulfate radicals. The apparent degradation rate constant of BPA on N-RGO was 0.71 min(-1), being about 700 times that (0.001 min(-1)) on N-free RGO. In mixtures of various phenols, the degradation rate constant of each phenol was linearly increased with its adsorption capacity. A simultaneous use of N-RGO and persulfate yielded fast and efficient removal of bisphenols. The use of N-RGO (120 mg L(-1)) and persulfate (0.6 mmol L(-1)) almost completely removed the added bisphenols (0.385 mmol L(-1)) at pH 6.6 within 17 min. A mechanism study indicated that the adsorption enriched the pollutant, and the catalytically generated sulfate radicals rapidly degrade the adsorbed pollutant, accelerating in turn the adsorption of residual pollutant. PMID:25943004

  19. 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)

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

    2012-12-01

    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.

  20. [Degradation of azo dye acid orange 7(AO7) by heat, ZVI and heat/ZVI activated persulfate].

    PubMed

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

    2011-10-01

    Effects of temperatures, PS concentrations and ZVI dosages on AO7 decomposition were investigated in sole heat and ZVI activating systems. The degradation results of two systems were compared for selecting a better activating way for AO7 degradation and finally the two activating ways were combined for getting the optimal AO7 degradation efficiency. The degradation of AO7 by Heat/PS systems followed pseudo first-order kinetics. The reaction rates increased with increasing reaction temperatures (elevated from room temperature to 90 degrees C) and also increased when initial PS concentrations varied from 1 to 12 mmol x L(-1). For ZVI activating systems (ZVI/PS systems), the degradation rate of AO7 was the highest when ZVI dose was 0.2 g, and it reached to 95.6% within 90 min. Comparing ZVI/PS systems with Heat/PS systems, the results showed that the ZVI activation was a more effective way to activate PS than the heat activation for AO7 degradation. AO7 degradation processes by ZVI/heat/PS systems were two-stage pseudo first-order kinetic processes, and the combining of two activating ways significantly increased the reaction rates. By the addition of ZVI to the Heat/PS system, the apparent activation energy E(a) of AO7 degradation reduced from the original 130.26 kJ x mol(-1) to 27.70 kJ x mol(-1). PMID:22279907

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

    Microsoft Academic Search

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

    1981-01-01

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

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

    SciTech Connect

    Paul Fallgren

    2009-02-20

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

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

    SciTech Connect

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

    1986-07-01

    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.

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

    SciTech Connect

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

    1993-08-03

    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.

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

    SciTech Connect

    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

    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.

  6. Direct trifluoromethylthiolation of unactivated C(sp(3))-H using silver(I) trifluoromethanethiolate and potassium persulfate.

    PubMed

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

    2015-03-23

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

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

    E-print Network

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

  8. A novel three-dimensional spherical CuBi2O4 consisting of nanocolumn arrays with persulfate and peroxymonosulfate activation functionalities for 1H-benzotriazole removal

    NASA Astrophysics Data System (ADS)

    Oh, Wen-Da; Lua, Shun-Kuang; Dong, Zhili; Lim, Teik-Thye

    2015-04-01

    A novel CuBi2O4 consisting of self-assembled spherical nanocolumn arrays (CuB-H) was synthesized via a facile hydrothermal method. It was further modified by controlling the Cu : Bi ratio during synthesis to become an efficient bi-functional catalyst (CuB-2.5) activated persulfate (PS) and peroxymonosulfate (PMS) for 1H-benzotriazole (BTZ) removal. Characterization of CuB-2.5 using XRD, FESEM, FTIR, BET and XPS revealed that it was morphologically similar to CuB-H and the molecular formula, as determined from the XRD results, was Cu1.2Bi1.6O3.6 with 2.4% w/w of CuO. The CuB-2.5 catalyst exhibited superior performance for BTZ removal via PS and PMS activations over the Cu2+ (aq.), CuO, CuBi2O4 (CuB-M, microsphere) and CuB-H. The performance of CuB-2.5 was investigated at different initial PS/PMS dosages, initial catalyst loadings and initial BTZ concentrations. Interestingly, it was found that the inter- and intra-molecular hydrogen bondings play prominent roles in the BTZ removal mechanism in both the PS and PMS systems. Meanwhile, it is relatively easy to activate PMS, leading to a faster BTZ removal rate over the PS system. The intermediate products of BTZ degradation produced from the PS and PMS systems were similar, indicating a similar degradation pathway. The catalyst could still retain its morphology and can be reused multiple times.A novel CuBi2O4 consisting of self-assembled spherical nanocolumn arrays (CuB-H) was synthesized via a facile hydrothermal method. It was further modified by controlling the Cu : Bi ratio during synthesis to become an efficient bi-functional catalyst (CuB-2.5) activated persulfate (PS) and peroxymonosulfate (PMS) for 1H-benzotriazole (BTZ) removal. Characterization of CuB-2.5 using XRD, FESEM, FTIR, BET and XPS revealed that it was morphologically similar to CuB-H and the molecular formula, as determined from the XRD results, was Cu1.2Bi1.6O3.6 with 2.4% w/w of CuO. The CuB-2.5 catalyst exhibited superior performance for BTZ removal via PS and PMS activations over the Cu2+ (aq.), CuO, CuBi2O4 (CuB-M, microsphere) and CuB-H. The performance of CuB-2.5 was investigated at different initial PS/PMS dosages, initial catalyst loadings and initial BTZ concentrations. Interestingly, it was found that the inter- and intra-molecular hydrogen bondings play prominent roles in the BTZ removal mechanism in both the PS and PMS systems. Meanwhile, it is relatively easy to activate PMS, leading to a faster BTZ removal rate over the PS system. The intermediate products of BTZ degradation produced from the PS and PMS systems were similar, indicating a similar degradation pathway. The catalyst could still retain its morphology and can be reused multiple times. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01428j

  9. A novel three-dimensional spherical CuBi2O4 consisting of nanocolumn arrays with persulfate and peroxymonosulfate activation functionalities for 1H-benzotriazole removal.

    PubMed

    Oh, Wen-Da; Lua, Shun-Kuang; Dong, Zhili; Lim, Teik-Thye

    2015-04-24

    A novel CuBi2O4 consisting of self-assembled spherical nanocolumn arrays (CuB-H) was synthesized via a facile hydrothermal method. It was further modified by controlling the Cu?:?Bi ratio during synthesis to become an efficient bi-functional catalyst (CuB-2.5) activated persulfate (PS) and peroxymonosulfate (PMS) for 1H-benzotriazole (BTZ) removal. Characterization of CuB-2.5 using XRD, FESEM, FTIR, BET and XPS revealed that it was morphologically similar to CuB-H and the molecular formula, as determined from the XRD results, was Cu1.2Bi1.6O3.6 with 2.4% w/w of CuO. The CuB-2.5 catalyst exhibited superior performance for BTZ removal via PS and PMS activations over the Cu(2+) (aq.), CuO, CuBi2O4 (CuB-M, microsphere) and CuB-H. The performance of CuB-2.5 was investigated at different initial PS/PMS dosages, initial catalyst loadings and initial BTZ concentrations. Interestingly, it was found that the inter- and intra-molecular hydrogen bondings play prominent roles in the BTZ removal mechanism in both the PS and PMS systems. Meanwhile, it is relatively easy to activate PMS, leading to a faster BTZ removal rate over the PS system. The intermediate products of BTZ degradation produced from the PS and PMS systems were similar, indicating a similar degradation pathway. The catalyst could still retain its morphology and can be reused multiple times. PMID:25874972

  10. Heterogeneous Degradation of Organic Pollutants by Persulfate Activated by CuO-Fe3O4: Mechanism, Stability, and Effects of pH and Bicarbonate Ions.

    PubMed

    Lei, Yang; Chen, Chuh-Shun; Tu, Yao-Jen; Huang, Yao-Hui; Zhang, Hui

    2015-06-01

    Magnetic CuO-Fe3O4 composite was fabricated by a simple hydrothermal method and characterized as a heterogeneous catalyst for phenol degradation. The effects of pH and bicarbonate ions on catalytic activity were extensively evaluated in view of the practical applications. The results indicated that an increase of solution pH and the presence of bicarbonate ions were beneficial for the removal of phenol in the CuO-Fe3O4 coupled with persulfate (PS) process. Almost 100% mineralization of 0.1 mM phenol can be achieved in 120 min by using 0.3 g/L CuO-Fe3O4 and 5.0 mM PS at pH 11.0 or in the presence of 3.0 mM bicarbonate. The positive effect of bicarbonate ion is probably due to the suppression of copper leaching as well as the formation of Cu(III). The reuse of catalyst at pH0 11.0 and 5.6 showed that the catalyst remains a high level of stability at alkaline condition (e.g., pH0 11.0). On the basis of the characterization of catalyst, the results of metal leaching and EPR studies, it is suggested that phenol is mainly destroyed by the surface-adsorbed radicals and Cu(III) resulting from the reaction between PS and Cu(II) on the catalyst. Taking into account the widespread presence of bicarbonate ions in waste streams, the CuO-Fe3O4/PS system may provide some new insights for contaminant removal from wastewater. PMID:25955238

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

    PubMed

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

    2015-02-01

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

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

    SciTech Connect

    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

    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).

  13. Heating activated red mud catalytic ozonation for degradation nitrobenzene from aqueous solution: performance and influence of preparation factors.

    PubMed

    Qi, Fei; Li, Huanan; Xu, Bingbing; Sun, Dezhi

    2014-09-01

    Red mud (RM), a waste residue of alumina refinery, has been used to develop an effective catalyst to enhance nitrobenzene (NB) removal from aqueous solution by ozonation. The result showed that the development of catalytic activity of RM was obtained by heating activation. The effects of different factors (heating temperature and time) have been examined in batch experiments. Sample prepared by heating RM at 400 degrees C for 4 h showed the highest activity in catalytic ozonation of NB. The temperature exhibited a significant effect on the performance of both NB removal and ozone decomposition. However, the effect of the heating time was insignificant. Experiments of both catalytic ozone decomposition and hydroxyl radical (*OH) inhibiting confirmed the existence of *OH in heated RM catalytic ozonation. According to the XRD pattern, the change of mineral content was the key reason for the development of catalytic activity, especially for hematite and magnetite. PMID:25924359

  14. 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)

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

    2012-10-01

    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.

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

    SciTech Connect

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

    1986-06-01

    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.

  16. Heat-activated thermosensitive liposomal cisplatin (HTLC) results in effective growth delay of cervical carcinoma in mice.

    PubMed

    Dou, Yannan N; Zheng, Jinzi; Foltz, Warren D; Weersink, Robert; Chaudary, Naz; Jaffray, David A; Allen, Christine

    2014-03-28

    Cisplatin (CDDP) has been identified as the primary chemotherapeutic agent for the treatment of cervical cancer, but dose limiting toxicity is a key issue associated with its clinical application. A suite of liposome formulations of CDDP has been developed in efforts to reduce systemic toxicity, but their therapeutic advantage over the free drug has been modest due to insufficient drug release at the tumor site. This report describes the development of a novel heat-activated thermosensitive liposome formulation containing CDDP (HTLC) designed to release approximately 90% of the loaded drug in less than 5min under mild heating conditions (42°C). Physico-chemical characteristics of HTLC were assessed in terms of gel to liquid crystalline phase transition temperature (Tm), drug loading efficiency, particle size, and stability. The pharmacokinetic profile and biodistribution of HTLC in non-tumor-bearing mice were evaluated over a 24h period. A sophisticated spatio-temporal elucidation of HTLC release in tumor-bearing mice was achieved by way of real-time monitoring using a magnetic resonance (MR) imaging protocol, wherein a custom-built laser-based conformal heat source was applied at the tumor volume to trigger the release of HTLC co-encapsulated with the MR contrast agent gadoteridol (Gd-HP-DO3A). MR thermometry (MRT) demonstrated that a relatively uniform temperature distribution was achieved in the tumor volume using the external laser-based heating setup. In mice bearing subcutaneously-implanted ME-180 cervical tumors, the combination of HTLC and heat resulted in a 2-fold increase in tumor drug levels at 1h post-administration compared to HTLC without heating. Furthermore, the overall tumor accumulation levels for the HTLC groups (with and without heat) at 1h post-injection were significantly higher than the corresponding free CDDP group. This translated into a significant improvement in therapeutic efficacy evaluated as tumor growth delay (p<0.05) for the heated HTLC treatment group compared to the unheated HTLC, heated or unheated free CDDP, and saline groups. Overall, findings from this study demonstrate that a heat-activated, triggered release formulation of CDDP results in a significant enhancement in the therapeutic index of this drug. PMID:24440663

  17. A combined coarse-grained and all-atom simulation of TRPV1 channel gating and heat activation.

    PubMed

    Zheng, Wenjun; Qin, Feng

    2015-05-01

    The transient receptor potential (TRP) channels act as key sensors of various chemical and physical stimuli in eukaryotic cells. Despite years of study, the molecular mechanisms of TRP channel activation remain unclear. To elucidate the structural, dynamic, and energetic basis of gating in TRPV1 (a founding member of the TRPV subfamily), we performed coarse-grained modeling and all-atom molecular dynamics (MD) simulation based on the recently solved high resolution structures of the open and closed form of TRPV1. Our coarse-grained normal mode analysis captures two key modes of collective motions involved in the TRPV1 gating transition, featuring a quaternary twist motion of the transmembrane domains (TMDs) relative to the intracellular domains (ICDs). Our transition pathway modeling predicts a sequence of structural movements that propagate from the ICDs to the TMDs via key interface domains (including the membrane proximal domain and the C-terminal domain), leading to sequential opening of the selectivity filter followed by the lower gate in the channel pore (confirmed by modeling conformational changes induced by the activation of ICDs). The above findings of coarse-grained modeling are robust to perturbation by lipids. Finally, our MD simulation of the ICD identifies key residues that contribute differently to the nonpolar energy of the open and closed state, and these residues are predicted to control the temperature sensitivity of TRPV1 gating. These computational predictions offer new insights to the mechanism for heat activation of TRPV1 gating, and will guide our future electrophysiology and mutagenesis studies. PMID:25918362

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

    PubMed

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

    2013-04-01

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

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

    SciTech Connect

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

    1985-09-30

    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.

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

    SciTech Connect

    Frei, Heinz; Han, Hongxian; Frei, Heinz

    2008-06-03

    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.

  1. Sensitizer-catalyst assemblies for water oxidation.

    PubMed

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

    2015-03-16

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

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

    SciTech Connect

    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

    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.

  3. Solid-liquid separation of oxidized americium from fission product lanthanides

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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.

  4. 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 ...

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

    PubMed

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

    2008-02-21

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

  6. Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater.

    PubMed

    Mahdi-Ahmed, Moussa; Chiron, Serge

    2014-01-30

    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

  7. Homogeneous and heterogeneous AOPs for rapid degradation of Triton X-100 in aqueous media via UV light, nano titania hydrogen peroxide and potassium persulfate

    Microsoft Academic Search

    J. Saien; Z. Ojaghloo; A. R. Soleymani; M. H. Rasoulifard

    2011-01-01

    Feasibility of degradation of Triton X-100 as a widely used and resistive surfactant in aqueous media was studied via some homogeneous and heterogeneous AOPs of UV\\/TiO2, UV\\/H2O2 and UV\\/S2O82?. For treatment of solutions containing 20mg\\/L of Triton, the optimum obtained conditions are: 5.0mg\\/L of nano TiO2, 270.3mg\\/L of KPS, and 34.0mg\\/L of H2O2 (1mM of the oxidants), initial natural pH

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

    E-print Network

    Sarwar, Muhammad Usman

    2012-02-14

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

  9. Microbial dechlorination activity during and after chemical oxidant treatment.

    PubMed

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

    2013-11-15

    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

  10. Magnesium Oxide

    MedlinePLUS

    Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some ... to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative ...

  11. Oxides (GCMP)

    NSDL National Science Digital Library

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

  12. Ethylene Oxide

    Cancer.gov

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

  13. Chitosan based heterogeneous catalyses: chitosan-grafted-poly(4-vinylpyridne) as an efficient catalyst for Michael additions and alkylpyridazinyl carbonitrile oxidation.

    PubMed

    Khalil, Khaled D; Al-Matar, Hamad M

    2013-01-01

    Chitosan-grafted-poly(4-vinylpyridine) (Cs-PVP) copolymers could be synthesized under heterogeneous conditions in presence of a potassium persulfate and sodium sulfite redox system. The synthesized graft copolymer could be utilized effectively, in the form of beads, as an efficient catalyst for Michael additions of active methylenes to functionally substituted alkenes. Moreover, methyl moiety oxidation in methyl pyridazinyl carbonitriles by H?O? in the presence of chitosan-g-polyvinyl pyridine-supported iron (III) complex, Cs-PVP/Fe, could be affected. A variety of pyrans, naphthopyrans, and thiopyrans could be synthesized efficiently in the presence of these graft copolymer beads by novel catalytic routes. These polymeric catalysts could be used instead of the old toxic commercial organic basic catalysts, piperidine or pyridine, and could be readily isolated from the reaction mixture and recycled several times without significant loss of catalytic activity. PMID:23698043

  14. Siderite, oxidation, and neutralization potential determination 

    E-print Network

    Porter, Elizabeth Brooke

    2001-01-01

    reactions of FeCO? under various testing conditions as related to NP determination as well as accuracy of the NP method. The effects of hydrogen peroxide (H?O?), potassium persulfate (K?S?O?), and potassium permanganate (KMnO?) on the NP of mixed overburden...

  15. PEGylated liposomes with NGR ligand and heat-activable cell-penetrating peptide-doxorubicin conjugate for tumor-specific therapy.

    PubMed

    Yang, Yanfang; Yang, Yang; Xie, Xiangyang; Cai, Xingshi; Zhang, Hui; Gong, Wei; Wang, Zhiyuan; Mei, Xingguo

    2014-05-01

    Cell-penetrating peptides (CPPs) mediated tumor-oriented nanocarriers have been widely studied by researchers recently. However, applications of CPPs in vivo were usually hampered by their loss in untargeted tissues and enzymatic degradation. These shortfalls required strategies to camouflage CPPs before their arrival at the targeted site. In this work, we constructed a thermosensitive liposome (TSL) containing Asparagines-Glycine-Arginine (NGR) peptide as the targeting moiety and heat-activable cell-penetrating peptide-doxorubicin conjugate for enhancing specific cancer therapy. Different to the masking strategies of CPPs reported, CPPs existing in conjugation form of CPPs and doxorubicin (CPP-Dox) were hidden in TSL to cloak and protect CPPs. Meanwhile, NGR moiety and local tumor hyperthermia were utilized to achieve specific targeting of CPPs to the tumor. The nanocarrier (CPP-Dox/NGR-TSL) prepared in this work possessed suitable physiochemical properties such as small particle size of about 90 nm, high drug encapsulation efficiency of approximately 95%, good stability in the medium containing 10% fetal bovine serum (FBS) and so on. In vitro experiments on Human fibrosarcoma cells (HT-1080) and human breast adenocarcinoma cells (MCF-7) verified the specific targeting ability and enhanced intracellular drug delivery of the liposomes to HT-1080 cells. Furthermore, comparing with NGR-targeted TSL containing Dox (Dox/NGR-TSL), the results of intravenous administration showed CPP-Dox/NGR-TSL significantly inhibited tumor growth in nude mice xenografted HT-1080 tumors and excellent body safety. In conclusion, the nanocarrier constructed in this study would be a safe and efficiently drug delivery system for specific cancer treatment. PMID:24565519

  16. Oxide Spintronics

    Microsoft Academic Search

    Manuel Bibes; Agns Barthelemy

    2007-01-01

    Concomitant with the development of metal-based spintronics in the late 1980s and 1990s, important advances were made on the growth of high-quality oxide thin films and heterostructures. While this was at first motivated by the discovery of high-temperature superconductivity in perovskite Cu oxides, this technological breakthrough was soon applied to other transition-metal oxides and, notably, mixed-valence manganites. The discovery of

  17. TRPV3 regulates nitric oxide synthase-independent nitric oxide synthesis in the skin.

    PubMed

    Miyamoto, Takashi; Petrus, Matt J; Dubin, Adrienne E; Patapoutian, Ardem

    2011-01-01

    Nitric oxide (NO) is an unstable signalling molecule synthesized de novo mainly from L-arginine by NO synthase (NOS) enzymes. Nitrite reduction can also produce NO, predominantly within body fluids (for example, saliva, sweat and blood plasma) and under extreme hypoxic and acidic conditions. It remains unknown if intracellular canonical signalling pathways regulate nitrite-dependent NO production. Here we examine NO production in the skin, a hypoxic tissue enriched in nitrites wherein NO has important roles in wound healing and other biological processes. We show that activation of TRPV3, a heat-activated transient receptor potential ion channel expressed in keratinocytes, induces NO production via a nitrite-dependent pathway. TRPV3 and nitrite are involved in keratinocyte migration in vitro and in wound healing and thermosensory behaviours in vivo. Our study demonstrates that activation of an ion channel can induce NOS-independent NO production in keratinocytes. PMID:21712817

  18. Methanol oxidation on semiconducting oxides

    Microsoft Academic Search

    J. Estellé; J. E. Sueiras

    1993-01-01

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

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

    E-print Network

    Seitzinger, Sybil

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

  20. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

    E-print Network

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

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

    SciTech Connect

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

    1984-07-01

    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.

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

    SciTech Connect

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

    1981-11-12

    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.

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

    PubMed

    Deng, Yang; Ezyske, Casey M

    2011-11-15

    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

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

    PubMed

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

    2013-02-01

    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

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

    NASA Astrophysics Data System (ADS)

    Calvert, Craig A.

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

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

    USGS Publications Warehouse

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

    1999-01-01

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

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

    SciTech Connect

    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

    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).

  9. Oxidation catalyst

    DOEpatents

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

    2010-11-09

    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.

  10. Oxide Thermoelectrics

    SciTech Connect

    Singh, David J [ORNL

    2008-01-01

    Thermoelectricity in oxides, especially NaxCoO2 and related materials, is discussed from the point of view of first principles calculations and Boltzmann transport theory. The electronic structure of this material is exceptional in that it has a combination of very narrow bands and strong hybridization between metal d states and ligand p states. As shown within the framework of conventional Boltzmann transport theory, this leads to high Seebeck coefficients even at metallic carrier densities. This suggests a strategy of searching for other narrow band oxides that can be doped metallic with mobile carriers. Some possible avenues for finding such materials are suggested.

  11. Water oxidation by lambda-MnO2: catalysis by the cubical Mn4O4 subcluster obtained by delithiation of spinel LiMn2O4.

    PubMed

    Robinson, David M; Go, Yong Bok; Greenblatt, Martha; Dismukes, G Charles

    2010-08-25

    Nanocrystalline spinel LiMn(2)O(4) has been prepared and treatment of LiMn(2)O(4) with dilute nitric acid solution resulted in the delithiation of the framework, while maintaining the spinel structure, lambda-MnO(2). LiMn(2)O(4) is not a catalyst for water oxidation. Upon removal of the lithium, the cubical Mn(4)O(4) cores become active sites for oxidizing water to molecular oxygen, which was investigated with the photochemical [Ru(2+)(2,2'-bpy)(3)]/persulfate system at pH 5.8. The nanosize lambda-MnO(2) obtained from the nanocrystalline LiMn(2)O(4), which was synthesized by the citrate route, shows a significantly higher water oxidation catalytic activity (Turnover Frequency: 3 x 10(-5) mol O(2)/s/mol Mn) than that obtained via solid state reaction with micrometer and irregular particle sizes (Turnover Frequency: 5 x 10(-6) mol O(2)/s/mol Mn). PMID:20672802

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

    PubMed

    Xiang, Rui; Ding, Yong; Zhao, Junwei

    2014-11-01

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

  13. 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...

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

    SciTech Connect

    Paul Fallgren

    2009-03-06

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

  15. Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate.

    PubMed

    Lee, Young Ae; Yun, Byeong Hwa; Kim, Seog K; Margolin, Yelena; Dedon, Peter C; Geacintov, Nicholas E; Shafirovich, Vladimir

    2007-01-01

    Peroxynitrite is produced during inflammation and combines rapidly with carbon dioxide to yield the unstable nitrosoperoxycarbonate, which decomposes (in part) to CO(3) (.-) and (.)NO(2) radicals. The CO(3) (.-) radicals oxidize guanine bases in DNA through a one-electron transfer reaction process that ultimately results in the formation of stable guanine oxidation products. Here we have explored these mechanisms, starting with a spectroscopic study of the kinetics of electron transfer from 20-22mer double-stranded oligonucleotides to CO(3) (.-) radicals, together with the effects of base sequence on the formation of the end-products in runs of one, two, or three contiguous guanines. The distributions of these alkali-labile lesions were determined by gel electrophoresis methods. The cascade of events was initiated through the use of 308 nm XeCl excimer laser pulses to generate CO(3) (.-) radicals by an established method based on the photodissociation of persulfate to sulfate radicals and the oxidation of bicarbonate. Although the Saito model (Saito et al., J. Am. Chem. Soc. 1995, 117, 6406-6407) predicts relative ease of one-electron oxidations in DNA, following the trend 5'-GGG > 5'-GG > 5'-G, we found that the rate constants for CO(3) (.-)-mediated oxidation of guanines in these sequence contexts (k(5)) showed only small variation within a narrow range [(1.5-3.0)x10(7) M(-1) s(-1)]. In contrast, the distributions of the end-products are dependent on the base sequence context and are higher at the 5'-G in 5'-GG sequences and at the first two 5'-guanines in the 5'-GGG sequences. These effects are attributed to a combination of initial hole distributions among the contiguous guanines and the subsequent differences in chemical reaction yields at each guanine. The lack of dependence of k(5) on sequence context indicates that the one-electron oxidation of guanine in DNA by CO(3) (.-) radicals occurs by an inner-sphere mechanism. PMID:17335089

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

    PubMed

    Shi, Kaiyuan; Zhitomirsky, Igor

    2013-12-26

    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

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

    NASA Astrophysics Data System (ADS)

    Burkhardt, Mark R.; Brenton, Ronald W.; Kammer, James A.; Jha, Virenda K.; O'Mara-Lopez, Peggy G.; Woodworth, Mark T.

    1999-01-01

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

  18. Asphalt Oxidation Kinetics and Pavement Oxidation Modeling 

    E-print Network

    Jin, Xin

    2012-07-16

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

  19. PREFACE: Semiconducting oxides Semiconducting oxides

    NASA Astrophysics Data System (ADS)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    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

  20. Oxidation resistance of silicon ceramics

    NASA Technical Reports Server (NTRS)

    Yasutoshi, H.; Hirota, K.

    1984-01-01

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

  1. Oxidative tritium decontamination system

    Microsoft Academic Search

    2006-01-01

    The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The OTDS employs ozone gas as oxidizing agent to convert elemental tritium to tritium oxide. Tritium oxide vapor and excess ozone gas is purged from the OTDS, for discharge to atmosphere or transport to further process. An effluent stream is

  2. Oxidative Tritium Decontamination System

    Microsoft Academic Search

    Gentile; Charles A

    2006-01-01

    The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The OTDS employs ozone gas as oxidizing agent to convert elemental tritium to tritium oxide. Tritium oxide vapor and excess ozone gas is purged from the OTDS, for discharge to atmosphere or transport to further process. An effluent stream is

  3. Thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  4. Designing oxidation catalysts

    Microsoft Academic Search

    Graham J. Hutchings; Stuart H. Taylor

    1999-01-01

    A simplified approach is described for the design of oxidation catalysts. It is based on three components and for selective oxidation the approach involves identifying catalysts that (a) do not catalyse the oxidation of the required product under the reaction conditions to be tested, (b) activate the oxidant and (c) activate the substrate. This approach is initially demonstrated to identify

  5. Fluorescent graphene oxide via polymer grafting: an efficient nanocarrier for both hydrophilic and hydrophobic drugs.

    PubMed

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

    2015-02-18

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

  6. The Enzymatic Oxidation of Graphene Oxide

    PubMed Central

    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

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

  7. Zinc oxide hexagram whiskers

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  8. Advances in heat-activated cooling systems

    Microsoft Academic Search

    W. M. Worek; D. Novosel; R. K. Collier

    1996-01-01

    Regulatory issues are fundamentally changing the heating, ventilation, and air-conditioning (HVAC) market. Growing concerns about indoor air quality, the phase-out of traditional refrigerants, and renewed emphasis on energy efficiency threaten the future of traditional vapor-compression refrigeration cycles. The air conditioner of the future will have to efficiently provide increased amounts of ventilation air, avoid the use of chlorofluorocarbons or similar

  9. Nitric oxide, oxidants, and protein tyrosine nitration

    Microsoft Academic Search

    Rafael Radi

    2004-01-01

    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

  10. Bridged graphite oxide materials

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  11. Thermal oxidation of silicides

    NASA Astrophysics Data System (ADS)

    Lie, L. N.; Tiller, W. A.; Saraswat, K. C.

    1984-10-01

    Kinetics of thermal oxide growth on silicides MoSi2, WSi2, TaSi2, and TiSi2 deposited over polycrystalline and single-crystal silicon were investigated. Both steam and dry O2 oxidations in the temperature range of 750-1200 °C were examined. An oxidation kinetic model for silicides which accounts for diffusion processes of silicon through the silicide layer and oxidant through the growing oxide, and the interface chemical reaction was developed. This model uses the Deal-Grove silicon oxidation approach. The significantly larger linear rate constants and greatly reduced activation energies of the linear rate constants of silicides in relation to single-crystal silicon oxidations are predicted by this model. The similarity of parabolic rate constants and their activation energies for silicon oxidations is also in excellent agreement with the model.

  12. Electrolytic oxidation of anthracite

    USGS Publications Warehouse

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

    1981-01-01

    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.

  13. Oxidant, Mitochondria and Calcium

    Microsoft Academic Search

    Tapati Chakraborti; Sudip Das; Malay Mondal; Sujata Roychoudhury; Sajal Chakraborti

    1999-01-01

    Mitochondria are active in the continuous generation of reactive oxygen species (ROS), (e.g., superoxide), thereby favouring a situation of mitochondrial oxidative stress. Under oxidative stress—for example, ischaemia–reoxygenation injury to cells—mitochondria form superoxide, which in turn is converted to hydrogen peroxide and the potent reactive species, hydroxyl radical. Alternatively, mitochondrial superoxide may react with nitric oxide to form potent oxidant peroxynitrite

  14. Oxidation in rheumatoid arthritis

    Microsoft Academic Search

    Carol A Hitchon; Hani S El-Gabalawy

    2004-01-01

    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

  15. Zinc oxide hexagram whiskers

    Microsoft Academic Search

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

    2006-01-01

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

  16. Solid Oxide Fuel Cell

    NSDL National Science Digital Library

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

  17. Comparison of the Catalytic Oxidation Reaction on Graphene Oxide and Reduced Graphene Oxide

    E-print Network

    Kim, Sehun

    Comparison of the Catalytic Oxidation Reaction on Graphene Oxide and Reduced Graphene Oxide Laboratory (PAL), Pohang 790-784, Republic of Korea ABSTRACT: The capacities of graphene oxide (GO) and reduced graphene oxide (rGO) films grown on silicon substrate to cause the aniline to azobenzene oxidation

  18. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    SciTech Connect

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

    2008-01-01

    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.

  19. The selective catalytic reduction of nitric oxide with methane over scandium oxide, yttrium oxide and lanthanum oxide

    Microsoft Academic Search

    Mark D Fokema; Jackie Y Ying

    1998-01-01

    The selective catalytic reduction of nitric oxide with methane over nanocrystalline Group IIIB metal oxides was investigated between 400°C and 675°C. Scandium oxide and yttrium oxide are better catalysts than lanthanum oxide because they have a greater specific activity and selectivity. The activity of yttrium oxide is 75% of that of Co-ZSM-5 at 600°C and yttrium oxide was also found

  20. The Atomic Structure of Oxide\\/Oxide Interface

    Microsoft Academic Search

    Qi-Hui Wu

    2011-01-01

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

  1. Thin zinc oxide and cuprous oxide films for photovoltaic applications

    Microsoft Academic Search

    Seongho Jeong

    2010-01-01

    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

  2. REVERSIBLE SOLID OXIDE CELLS

    Microsoft Academic Search

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

    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.

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

    SciTech Connect

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    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.

  4. Mixed oxide solid solutions

    DOEpatents

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

    2003-01-01

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

  5. 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)

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

    2013-05-01

    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.

  6. Oxidants and oxidation in the Earth's atmosphere

    NASA Technical Reports Server (NTRS)

    1995-01-01

    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.

  7. UV Induced Oxidation of Nitric Oxide

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    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.

  8. Structures of Selenomonas ruminantium Phytase in Complex with Persulfated Phytate

    Microsoft Academic Search

    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

    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)

  9. Transparent Conducting Oxides Based on Tin Oxide

    Microsoft Academic Search

    Robert Kykyneshi; Jin Zeng; David P. Cann

    \\u000a Tin oxide (SnO2) is an important and widely used wide band-gap semiconductor and is part of a family of binary transparent conducting oxides\\u000a (TCO), such as Sn- and ZnO-doped In2O3 (ITO, ZIO) [1] and ZnO:Al [2], CdO. It is of great interest in corrosive environment applications due to its high stability. This includes applications\\u000a such as batteries, low emission windows

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

    E-print Network

    Poeppelmeier, Kenneth R.

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

  11. Solid Oxide Fuel Cells

    NSDL National Science Digital Library

    Crawley, Gemma

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

  12. Oxide dispersion strengthened superalloy

    NASA Technical Reports Server (NTRS)

    Glasgow, T. K.; Kim, Y. G.; Curwick, L. R.; Merrick, H. F.

    1981-01-01

    MA6000E alloy is strengthened at high temperatures by dispersion of yttrium oxide. Strength properties are about twice those of conventional nickel base alloys. Good thermal fatigue, intermediate temperature strength, and good oxidation resistance give alloy unique combination of benefits. Application in aircraft gas turbine is improved.

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

    Microsoft Academic Search

    N. Izyumskaya; Ya. Alivov; H. Morkoç

    2009-01-01

    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

  14. Stabilized chromium oxide film

    DOEpatents

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

    1988-01-01

    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.

  15. Stabilized chromium oxide film

    DOEpatents

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

    1986-08-04

    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.

  16. Oxidative stress in plants

    Microsoft Academic Search

    Dirk Inzé; Marc Van Montagu

    1995-01-01

    During the past few years, considerable progress has been made in understanding how plants protect themselves against oxidative stress. Genes encoding plant antioxidant enzymes have been cloned and characterized. Overproduction of superoxide dismutases and glutathione reductase has been shown to confer increased tolerance to oxidative stress. Several lines of evidence have revealed an important role for hydrogen peroxide in stress-induced

  17. Partial Oxidation of Methane

    Microsoft Academic Search

    R. Pitchai; K. Klier

    1986-01-01

    Partial oxidation is a widely used process to convert hydrocarbons and alcohols to valuable oxygen-containing chemicals. Although methane is the simplest hydrocarbon which gives formaldehyde and methanol as partial oxidation products, the direct utilization of these reactions for the manufacture of formaldehyde and methanol has remained extremely difficult. During the 1940s, two processes for the conversion of methane to formaldehyde

  18. NEPTUNIUM OXIDE PROCESSING

    Microsoft Academic Search

    J Jordan; R Watkins; S Hensel

    2009-01-01

    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

  19. Monolithic metal oxide transistors.

    PubMed

    Choi, Yongsuk; Park, Won-Yeong; Kang, Moon Sung; Yi, Gi-Ra; Lee, Jun-Young; Kim, Yong-Hoon; Cho, Jeong Ho

    2015-04-28

    We devised a simple transparent metal oxide thin film transistor architecture composed of only two component materials, an amorphous metal oxide and ion gel gate dielectric, which could be entirely assembled using room-temperature processes on a plastic substrate. The geometry cleverly takes advantage of the unique characteristics of the two components. An oxide layer is metallized upon exposure to plasma, leading to the formation of a monolithic source-channel-drain oxide layer, and the ion gel gate dielectric is used to gate the transistor channel effectively at low voltages through a coplanar gate. We confirmed that the method is generally applicable to a variety of sol-gel-processed amorphous metal oxides, including indium oxide, indium zinc oxide, and indium gallium zinc oxide. An inverter NOT logic device was assembled using the resulting devices as a proof of concept demonstration of the applicability of the devices to logic circuits. The favorable characteristics of these devices, including (i) the simplicity of the device structure with only two components, (ii) the benign fabrication processes at room temperature, (iii) the low-voltage operation under 2 V, and (iv) the excellent and stable electrical performances, together support the application of these devices to low-cost portable gadgets, i.e., cheap electronics. PMID:25777338

  20. Selective methane oxidation over promoted oxide catalysts

    Microsoft Academic Search

    K. Klier; R. G. Herman

    1995-01-01

    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 time yields of Câ hydrocarbon products, formaldehyde, and methanol from methane\\/air mixtures at moderate temperatures and at ambient pressure. The accomplishments can be

  1. Regenerative catalytic oxidation

    SciTech Connect

    Gribbon, S.T. [Engelhard Process Emission Systems, South Lyon, MI (United States)

    1996-12-31

    Currently Regenerative Thermal Oxidizers (R.T.O.`s) are an accepted technology for the control of volatile organic compounds (VOC`s) and hazardous air pollutants (HAP`s). This control technology, when introduced, offered substantial reductions in operating costs, especially auxiliary fuel requirements when compared to existing control technologies such as recuperative thermal and recuperative catalytic oxidizers. While these savings still exist, there is a demand for control of new and/or hybrid technologies, one of which is Regenerative Catalytic Oxidizers (R.C.O.`s). This paper will explore the development of regenerative catalytic oxidation from the theoretical stage through pilot testing through a commercial installation. The operating cost of R.C.O.`s will be compared to R.T.O.`s to verify the savings that are achievable through the use of regenerative catalytic oxidation. In the development of this technology, which is a combination of two (2) existing technologies, R.T.O.`s and catalysis, a second hybrid technology was explored and pilot tested. This is a combination R.C.O. for VOC and HAP control and simultaneous SCR (Selective Catalytic Reduction) for NOx (Oxides of Nitrogen) control. Based on the pilot and full scale testing, both regenerative catalytic oxidizers and systems which combine R.C.O. with SCR for both VOC and NOx reduction are economically viable and are in fact commercially available. 6 figs., 2 tabs.

  2. Wet Oxidation Process

    NSDL National Science Digital Library

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

  3. Dry Thermal Oxidation Process

    NSDL National Science Digital Library

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

  4. Jeff Koebbe Nitrous Oxide

    E-print Network

    Toohey, Darin W.

    of nitrogen) 60% in our atmosphere occurs naturally from mainly rainforests and plant matter decomp. 10 conditions can release as much nitrous oxide as the world's rainforests Ozone killer: NOAA found N2O is 1

  5. Oxidative acylation using thioacids

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.

    1997-01-01

    Several important prebiotic reactions, including the coupling of amino acids into polypeptides by the formation of amide linkages, involve acylation. Theae reactions present a challenge to the understanding of prebiotic synthesis. Condensation reactions relying on dehydrating agents are either inefficient in aqueous solution or require strongly acidic conditions and high temperatures. Activated amino acids such as thioester derivatives have therefore been suggested as likely substrates for prebiotic peptide synthesis. Here we propose a closely related route to amide bond formation involving oxidative acylation by thioacids. We find that phenylalanine, leucine and phenylphosphate are acylated efficiently in aqueous solution by thioacetic acid and an oxidizing agent. From a prebiotic point of view, oxidative acylation has the advantage of proceeding efficiently in solution and under mild conditions. We anticipate that oxidative acylation should prove to be a general method for activating carboxylic acids, including amino acids.

  6. Oxidative Tritium Decontamination System

    DOEpatents

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

    2006-02-07

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

  7. Mercuric oxide poisoning

    MedlinePLUS

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

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

    ERIC Educational Resources Information Center

    Tudela, David

    2008-01-01

    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

  9. Oxidation of propylene over copper oxide catalysts 

    E-print Network

    Billingsley, David Stuart

    1958-01-01

    are to be found in the patent literature which is often not particularly informative. Discussion of this material has, therefore been reserved for a subsequent section of this survey. If view of the considerable activity in most phases of the petro- chemicals... of compositions explored, oxygen oxidation resulted in four times the space time yields and approximately six times the acetaIdehyde concentration in the product. Patent Literature The literature surveyed in this section consisted of patents which appear'ed...

  10. Controlled CO preferential oxidation

    DOEpatents

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

    1997-06-10

    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.

  11. CCMR: Cobalt Oxide Nanocubes

    NSDL National Science Digital Library

    Lee, Sabrina R.

    2009-08-15

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

  12. Oxidative stress in plants

    Microsoft Academic Search

    Grzegorz Bartosz

    1997-01-01

    Oxidative stress, defined as a shift of the balance between prooxidative and antioxidative reactions in favor of the former\\u000a seems to be a common denominator of the action of various agents on living organisms. This review briefly presents the sources\\u000a of reactive oxygen species and means of antioxidative defense in plants, means of assessment of oxidative stress and exemplary\\u000a data

  13. 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.

  14. Solid Oxide Fuel Cells

    Microsoft Academic Search

    Nigel M. Sammes; Roberto Bove; Jakub Pusz

    A Solid Oxide Fuel Cell (SOFC) is typically composed of two porous electrodes, interposed between an electrolyte made of a\\u000a particular solid oxide ceramic material. The system originates from the work of Nernst in the nineteenth century. In his patent\\u000a [1], Nernst proposed that a solid electrolyte could be made to electrically conduct, using a heater; the system then “glowed”

  15. Structural Studies of Oxide Surfaces

    NASA Astrophysics Data System (ADS)

    Gustafsson, T.; Garfunkel, E.; Gusev, E. P.; Häberle, P.; Lu, H. C.; Zhou, J. B.

    We review some recent ion scattering experiments on the structure of oxide surfaces. We show that the MgO(100) surface exhibits very small surface distortions, in agreement with recent theoretical work. For the case of the oxidation of Si(100), we show that the oxidation proceeds in three different spatially separate regions, something which disagrees with the conventional model for silicon oxidation.

  16. Oxide fiber targets at ISOLDE

    Microsoft Academic Search

    U. Köster; U. C. Bergmann; D. Carminati; R. Catherall; J. Cederkäll; B. Crepieux; M. Dietrich; K. Elder; V. N. Fedoseyev; L. Fraile; S. Franchoo; H. Fynbo; U. Georg; T. Giles; A. Joinet; O. C. Jonsson; R. Kirchner; Ch. Lau; J. Lettry; H. J. Maier; V. I. Mishin; M. Oinonen; K. Peräjärvi; H. L. Ravn; T. Rinaldi; M. Santana-Leitner; U. Wahl; L. Weissman

    2003-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points.The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in

  17. ADVANCED OXIDATION PROCESS

    SciTech Connect

    Dr. Colin P. Horwitz; Dr. Terrence J. Collins

    2003-11-04

    The removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from automotive fuels is an integral component in the development of cleaner burning and more efficient automobile engines. Oxidative desulfurization (ODS) wherein the dibenzothiophene derivative is converted to its corresponding sulfoxide and sulfone is an attractive approach to sulfur removal because the oxidized species are easily extracted or precipitated and filtered from the hydrocarbon phase. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) catalytically convert dibenzothiophene and its derivatives rapidly and effectively at moderate temperatures (50-60 C) and ambient pressure to the corresponding sulfoxides and sulfones. The oxidation process can be performed in both aqueous systems containing alcohols such as methanol, ethanol, or t-butanol, and in a two-phase hydrocarbon/aqueous system containing tert-butanol or acetonitrile. In the biphasic system, essentially complete conversion of the DBT to its oxidized products can be achieved using slightly longer reaction times than in homogeneous solution. Among the key features of the technology are the mild reaction conditions, the very high selectivity where no over oxidation of the sulfur compounds occurs, the near stoichiometric use of hydrogen peroxide, the apparent lack of degradation of sensitive fuel components, and the ease of separation of oxidized products.

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

    SciTech Connect

    Tsai, Y.L.

    1986-01-01

    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.

  19. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1994-01-01

    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.

  20. Metal oxide-polymer composites

    NASA Technical Reports Server (NTRS)

    Wellinghoff, Stephen T. (Inventor)

    1997-01-01

    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.

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

    Microsoft Academic Search

    Israel E. Wachs

    1996-01-01

    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

  2. Enargite oxidation: A review

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

    Enargite, Cu 3AsS 4, 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 oxidized alteration mineral of enargite is probably scorodite, FeAsO 4.2H 2O, with iron provided most likely by pyrite, a phase almost ubiquitously associated with enargite. Other secondary minerals after enargite include arsenates such as chenevixite, Cu 2Fe 2(AsO 4) 2(OH) 4.H 2O, and ceruleite, Cu 2Al 7(AsO 4) 4.11.5H 2O, and sulphates such as brochantite, Cu 4(SO 4)(OH) 6, and posnjakite, Cu 4(SO 4)(OH) 6·H 2O. Detailed studies of enargite field alteration at Furtei, Sardinia, suggest that most alteration occurs through dissolution, as testified by the appearance of etch pits at the surface of enargite crystals. However, apparent replacement by scorodite and cuprian melanterite was observed. Bulk oxidation of enargite in air is a very slow process. However, X-ray photoelectron spectroscopy (XPS) reveals subtle surface changes. From synchrotron-based XPS it was suggested that surface As atoms react very fast, presumably by forming bonds with oxygen. Conventional XPS shows the formation, on aged samples, of a nanometer-size alteration layer with an appreciably distinct composition with respect to the bulk. Mechanical activation considerably increases enargite reactivity. In laboratory experiments at acidic to neutral pH, enargite oxidation/dissolution is slow, although it is accelerated by the presence of ferric iron and/or bacteria such as Acidithiobacillus ferrooxidans and Sulfolobus BC. In the presence of sulphuric acid and ferric iron, the reaction involves dissolution of Cu and formation of native sulphur, subsequently partly oxidized to sulphate. At alkaline pH, the reactivity of enargite is apparently slightly greater. XPS spectra of surfaces conditioned at pH 11 have been interpreted as evidence of formation of a number of surface species, including cupric oxide and arsenic oxide. Treatment with hypochlorite solutions at pH 12.5 quickly produces a coating of cupric oxide. Electrochemical oxidation of enargite typically involves low current densities, confirming that the oxidation process is slow. Important surface changes occur only at high applied potentials, e.g. + 0.74 V vs. SHE. It is confirmed that, at acidic pH, the dominant process is Cu dissolution, accompanied (at + 0.56 V vs. SHE, pH = 1) by formation of native sulphur. At alkaline pH, a number of surface products have been suggested, including copper and arsenic oxides, and copper arsenates. XPS studies of the reacted surfaces demonstrate the evolution of Cu from the monovalent to the divalent state, the formation of As-O bonds, and the oxidation of sulphur to polysulphide, sulphite and eventually sulphate. In most natural and quasi-natural (mining) situations, it is expected that enargite reactivity will be slow. Moreover, it is likely that the release of arsenic will be further slowed down by at least temporary trapping in secondary phases. Therefore, an adequate management of exposed surfaces and wastes should minimize the environmental impact of enargite-bearing deposits. In spite of an increasing body of data, there are several gaps in our knowledge of enargite oxidation. The exact nature of most mechanisms and products remains poorly constrained, and there is a lack of quantitative data on the dependence on parameters such as pH and dissolved oxygen.

  3. Stabilized tin-oxide-based oxidation/reduction catalysts

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    E-print Network

    Ward, Mark Branham

    1977-01-01

    THE OXIDATIVF, DEHYDROGENATION OF ETHANE WITH NITROUS OXIDE BY MOI. YBDENUM OXIDE SUFI?ORTED ON S1LICA GEL A Thesis by MARK BRANHAM WARD Submitted to the Graduate Colleg, of Texas A&M University in partial fulfillment of the requirement... for th degree of MASTER Ol' SCIENCE May 1977 Major Subject: Chemistry THE OXIDATIVE DEHYDROGENATION OF ETHANE WITH NITROUS OXIDE BY MOLYBDENUM OXIDE SUPPORTED ON SILICA GEL A Thesis by MARK BRANHAM WARD Approved as to style and content by...

  5. Methanol partial oxidation reformer

    DOEpatents

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

    1999-01-01

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

  6. Methanol partial oxidation reformer

    DOEpatents

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

    1999-08-24

    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.

  7. Methanol partial oxidation reformer

    DOEpatents

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

    1999-08-17

    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.

  8. Methanol partial oxidation reformer

    DOEpatents

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

    2001-01-01

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

  9. Biomimetic methane oxidation

    SciTech Connect

    Watkins, B.E.; Droege, M.W.; Taylor, R.T.; Satcher, J.H.

    1992-06-12

    Methane monooxygenase (MMO) is an enzyme found in methanotrophs that catalyses the selective oxidation of methane to methanol. MMO is protein complex one component of which is a binuclear metal center containing oxygenase. We have completed one round of a design/synthesis/evaluation cycle in the development of coordination complexes that mimic the structure/function of the MMO active site. One of these, a binuclear, coordinately-asymmetric copper complex, is capable of oxidizing cyclohexane to a mixture of cyclohexanol and cyclohexanone in the presence of hydrogen peroxide.

  10. Some Properties of Beryllium Oxide and Beryllium Oxide - Columbium Ceramals

    NASA Technical Reports Server (NTRS)

    Robards, C F; Gangler, J J

    1951-01-01

    High-temperature tensile and thermal-shock investigations were conducted on beryllium oxide and beryllium oxide plus columbium metal additions. X-ray diffraction and metallographic results are given. The tensile strength of 6150 pounds per square inch for beryllium oxide at 1800 degrees F compared favorably with the zirconia bodies previously tested. Additions of 2, 5, 8, 10, 12, and 15 percent by weight of columbium metal failed to improve the shock resistance over that of pure beryllium oxide.

  11. High dielectric constant gate oxides for metal oxide Si transistors

    Microsoft Academic Search

    John Robertson

    2006-01-01

    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 (kappa) or 'high K' gate oxides such as hafnium oxide

  12. Nanostructured transition metal oxides useful for water oxidation catalysis

    DOEpatents

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    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.

  13. The Fundamental Oxidation Kinetics Of Copper under Different Oxidizing Atmospheres

    NASA Astrophysics Data System (ADS)

    Yang, Judith; Bhardwaj, Mridula; Zhou, Guang-Wen; Tropia, Lori; Gibson, Murray

    2000-03-01

    Understanding the oxidation process is of fundamental and practical interest because thin film growth, such as ferroelectrics, corrosion, passivation, and some catalysis involve oxidation. However, there exists a surprising paucity of information concerning the transient oxidation stages, from the formation of the initial oxide to the growth of the thermodynamically-stable oxide. To bridge this gap, we are visualizing the initial oxidation of Cu(001) by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM). Oxidation potentially involves surface diffusion, nucleation and growth, which is strikingly similar to epitaxial deposition. For dry oxygen, we have developed a semi-quantitative model of the initial oxidation stage where the dominant mechanism is oxygen diffusion on the Cu surface. We will now focus on the role moisture plays in the solid state reactions involved in copper oxidation. Steam or hydrogen within the oxide scale is known to prevent loss of contact between the scale and the metal. Our initial observations show that water vapor reduces the oxide as well as reduce the rate of oxidation if both oxygen and water vapor are used.

  14. OXIDATIVE TREATMENT OF INDUSTRIAL WASTEWATER

    EPA Science Inventory

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

  15. Oxidative Stress and Psychological Disorders

    PubMed Central

    Salim, Samina

    2014-01-01

    Oxidative stress is an imbalance between cellular production of reactive oxygen species and the counteracting antioxidant mechanisms. The brain with its high oxygen consumption and a lipid-rich environment is considered highly susceptible to oxidative stress or redox imbalances. Therefore, the fact that oxidative stress is implicated in several mental disorders including depression, anxiety disorders, schizophrenia and bipolar disorder, is not surprising. Although several elegant studies have established a link between oxidative stress and psychiatric disorders, the causal relationship between oxidative stress and psychiatric diseases is not fully determined. Another critical aspect that needs much attention and effort is our understanding of the association between cellular oxidative stress and emotional stress. This review examines some of the recent discoveries that link oxidative status with anxiety, depression, schizophrenia and bipolar disorder. A discussion of published results and questions that currently exist in the field regarding a causal relationship between oxidative and emotional stress is also provided. PMID:24669208

  16. 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...

  17. Oxidative Stress in Myopia

    PubMed Central

    Francisco, Bosch-Morell; Salvador, Mérida; Amparo, Navea

    2015-01-01

    Myopia affected approximately 1.6 billion people worldwide in 2000, and it is expected to increase to 2.5 billion by 2020. Although optical problems can be corrected by optics or surgical procedures, normal myopia and high myopia are still an unsolved medical problem. They frequently predispose people who have them to suffer from other eye pathologies: retinal detachment, glaucoma, macular hemorrhage, cataracts, and so on being one of the main causes of visual deterioration and blindness. Genetic and environmental factors have been associated with myopia. Nevertheless, lack of knowledge in the underlying physiopathological molecular mechanisms has not permitted an adequate diagnosis, prevention, or treatment to be found. Nowadays several pieces of evidence indicate that oxidative stress may help explain the altered regulatory pathways in myopia and the appearance of associated eye diseases. On the one hand, oxidative damage associated with hypoxia myopic can alter the neuromodulation that nitric oxide and dopamine have in eye growth. On the other hand, radical superoxide or peroxynitrite production damage retina, vitreous, lens, and so on contributing to the appearance of retinopathies, retinal detachment, cataracts and so on. The objective of this review is to suggest that oxidative stress is one of the key pieces that can help solve this complex eye problem. PMID:25922643

  18. Hydrous oxide activated charcoal

    SciTech Connect

    Weller, J.P.

    1987-09-08

    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.

  19. Doped zinc oxide microspheres

    DOEpatents

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

    1993-01-01

    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.

  20. Mammalian nitric oxide synthases

    Microsoft Academic Search

    Dennis J Stuehr

    1999-01-01

    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.

  1. Solid Oxide Fuel Cells

    NSDL National Science Digital Library

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

  2. Oxidative Tritium Decontamination System

    Microsoft Academic Search

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

    2002-01-01

    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

  3. Metal oxide sensors

    Microsoft Academic Search

    H. Meixner; U. Lampe

    1996-01-01

    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.

  4. Highly oxidized superconductors

    DOEpatents

    Morris, Donald E. (Kensington, CA)

    1994-01-01

    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.

  5. Technology Offer Oxidized Phospholipids -

    E-print Network

    of Application Therapy of (a) skin cancers and b) their precursors: a) melanoma, basal cell carcinoma, squamous melanoma and other types of cancer have to be tested. Overview This invention deals with oxidized metastasizing and nonmetastasizing melanoma cells as well as malignant cells originating from keratinocytes

  6. Doped zinc oxide microspheres

    DOEpatents

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

    1993-12-14

    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.

  7. 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.

  8. Oxidative phosphorylation revisited.

    PubMed

    Nath, Sunil; Villadsen, John

    2015-03-01

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

  9. The anaerobic oxidation of ammonium

    Microsoft Academic Search

    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

    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

  10. Water treeing and polymer oxidation

    Microsoft Academic Search

    R. J. Densley; S. S. Bamji; A. T. Bulinski; J.-P. Crine

    1990-01-01

    The influence of oxidation on water tree degradation is examined. Studies of the thermal oxidation of cable-grade PE (polyethylene) and XLPE (cross-linked PE) and also of PE and XLPE immersed in hot aqueous solutions in the absence of an electric field are reviewed. The data are compared with the results of oxidation studies of water trees in PE and XLPE.

  11. 7, 78197841, 2007 VOC oxidation

    E-print Network

    Paris-Sud XI, Université de

    ACPD 7, 7819­7841, 2007 VOC oxidation products and new particle formation A. Laaksonen et al. Title Chemistry and Physics Discussions The role of VOC oxidation products in continental new particle formation A Physics, Heidelberg, Germany 7819 #12;ACPD 7, 7819­7841, 2007 VOC oxidation products and new particle

  12. Tailoring oxidation degrees of graphene oxide by simple chemical reactions

    SciTech Connect

    Wang Gongkai [Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education, Northeastern University, Shenyang, Liaoning 110004 (China); Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Sun Xiang; Lian Jie [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Liu Changsheng [Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education, Northeastern University, Shenyang, Liaoning 110004 (China)

    2011-08-01

    High quality graphene oxide (GO) with controllable degrees of oxidation was synthesized by simple chemical reactions inspired by approaches to unzip single wall carbon nanotubes using strong oxidizing agents. As compared to the conventional Hummers method, these reactions are less exo-therm involved without emission of toxic gases. The structural characteristics of the synthesized GO with various oxidation degrees were evaluated by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and UV-vis-IR spectroscopy. GO with tailored degrees of oxidation displays tunable optoelectronic properties and may have a significant impact on developing graphene- or GO-based platforms for various technological applications.

  13. Hydroxylamine oxidation and subsequent nitrous oxide production by the heterotrophic ammonia oxidizer Alcaligenes faecalis

    Microsoft Academic Search

    S. Otte; J. Schalk; J. G. Kuenen; M. S. M. Jetten

    1999-01-01

    Nitrous oxide (N2O), a greenhouse gas, is emitted during autotrophic and heterotrophic ammonia oxidation. This emission may result from either\\u000a coupling to aerobic denitrification, or it may be formed in the oxidation of hydroxylamine (NH2OH) to nitrite (NO2\\u000a ?). Therefore, the N2O production during NH2OH oxidation was studied with Alcaligenes faecalis strain TUD. Continuous cultures of A. faecalis showed increased

  14. Oxidation of Calcium Boride at High Temperature

    Microsoft Academic Search

    Jun-ichi Matsushita; Kiyotaka Mori; Yoshitake Nishi; Yutaka Sawada

    1998-01-01

    The oxidation of CaB6 powders at high temperatures was investigated. The sample oxidized at 873 to 973 K for 25 hours exhibited weight gain with increasing oxidation temperature; the oxidation proceeded in accordance with the parabolic law during the initial oxidation stage. On the other hand, the weight gain of the sample oxidized at and above 1073 K for 4

  15. Wet vs. Dry Oxidation Processes

    NSDL National Science Digital Library

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

  16. Surface Oxidation of Liquid Sn

    SciTech Connect

    Grigoriev,A.; Shpyrko, O.; Steimer, C.; Pershan, P.; Ocko, B.; Deutsch, M.; Lin, B.; Meron, M.; Graber, T.; Gebhardt, J.

    2005-01-01

    We report the results of an X-ray scattering study that reveals oxidation kinetics and formation of a previously unreported crystalline phase of SnO at the liquid-vapour interface of Sn. Our experiments reveal that the pure liquid Sn surface does not react with molecular oxygen below an activation pressure of {approx}5.0 x 10{sup -6} Torr. Above that pressure a rough solid Sn oxide grows over the liquid metal surface. Once the activation pressure has been exceeded the oxidation proceeds at pressures below the oxidation pressure threshold. The observed diffraction pattern associated with the surface oxidation does not match any of the known Sn oxide phases. The data have an explicit signature of the face-centered cubic structure, however it requires lattice parameters that are about 9% smaller than those reported for cubic structures of high-pressure phases of Sn oxides.

  17. Molecular theory of graphene oxide.

    PubMed

    Sheka, Elena F; Popova, Nadezhda A

    2013-08-28

    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

  18. Promethium Oxide Structure

    Microsoft Academic Search

    Archie S. Wilson; F. P. Roberts; E. J. Wheelwright

    1963-01-01

    FROM the results of radiochemical distribution experiments, M. Bruno and U. Croatto1 concluded that over a large range of temperatures promethium sesquioxide has a fluorite-type structure. We have examined a sample of promethium sesquioxide powder by means of X-ray diffraction and have found reflexions which are consistent with a fluorite-type structure. The promethium-147 oxide was about 99 per cent pure

  19. Anaerobic Ammonium Oxidation (Anammox)

    Microsoft Academic Search

    C. Ryan Penton

    Anaerobic ammonium oxidation (anammox) is a recently discovered nitrogen removal pathway in natural systems. First found to\\u000a be a significant nitrogen sink in the Black Sea anoxic water column in 2003, anammox has shown to be responsible for as much\\u000a as 79% of N2 production in marine sediments. Little is known concerning the significance of anammox in freshwater systems and

  20. Oxidative Stress in Malaria

    PubMed Central

    Percário, Sandro; Moreira, Danilo R.; Gomes, Bruno A. Q.; Ferreira, Michelli E. S.; Gonçalves, Ana Carolina M.; Laurindo, Paula S. O. C.; Vilhena, Thyago C.; Dolabela, Maria F.; Green, Michael D.

    2012-01-01

    Malaria is a significant public health problem in more than 100 countries and causes an estimated 200 million new infections every year. Despite the significant effort to eradicate this dangerous disease, lack of complete knowledge of its physiopathology compromises the success in this enterprise. In this paper we review oxidative stress mechanisms involved in the disease and discuss the potential benefits of antioxidant supplementation as an adjuvant antimalarial strategy. PMID:23208374

  1. Zinc oxide hexagram microrods

    Microsoft Academic Search

    Guo Xing-Yuan; Ding Zhan-Hui; Zhou Jing; Xu Da-Peng

    2011-01-01

    Zinc oxide (ZnO) microrods were grown by the floating zone method, the as-grown ZnO microrods have uniform size. Scanning electron microscope image reveals that the ZnO microrods are grown with a hexagonal structure, well faceted ends and side surfaces. Most of ZnO microrods have diameters of about 20-30Jlm and lengths of about 1-2 mm. Polarizing microscopy image of ZnO microrods

  2. Nitric Oxide for Children

    Microsoft Academic Search

    Judy L. Aschner; Candice D. Fike; Eric Austin; J. Donald Moore; Frederick E. Barr

    \\u000a The introduction of inhaled nitric oxide (iNO) for the treatment of hypoxemic respiratory failure in neonates ushered in a\\u000a new era in neonatal intensive care. This inhalational therapeutic redefined the medical management of the infant with persistent\\u000a pulmonary hypertension of the newborn (PPHN). With a selective pulmonary vasodilator in hand, a kinder, gentler approach to\\u000a ventilation was embraced in many

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

    E-print Network

    Yang, Tsong-Jen

    1979-01-01

    THE OXIDATIVE DEHYDROGENATION OF ETHANE NITH NITROUS OXIDE BY MOLYBDENUM OXIDE SUPPORTED QN SILICA GEL A Tnesi- by Tsong-den Yang Submitted to the Graduate College of Texas ASM University in partial fulfillme. . t of the requiremert fcr... the degree of MASTER QF SCIENCE August 1979 Ma7or Sub]ect: Chemistry THE OXIDATIVE DEHYDROGENATION QF ETHANE WITH NITROUS OXI)3E BY MOLYBDENUM OXIDE SUPPORTED ON SILICA GEL A Thesis Tsong-Jen Yang Approved as to style and content by: (Chairman...

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

    E-print Network

    Yang, Tsong-Jen

    1979-01-01

    THE OXIDATIVE DEHYDROGENATION OF ETHANE NITH NITROUS OXIDE BY MOLYBDENUM OXIDE SUPPORTED QN SILICA GEL A Tnesi- by Tsong-den Yang Submitted to the Graduate College of Texas ASM University in partial fulfillme. . t of the requiremert fcr... the degree of MASTER QF SCIENCE August 1979 Ma7or Sub]ect: Chemistry THE OXIDATIVE DEHYDROGENATION QF ETHANE WITH NITROUS OXI)3E BY MOLYBDENUM OXIDE SUPPORTED ON SILICA GEL A Thesis Tsong-Jen Yang Approved as to style and content by: (Chairman...

  5. Phosphorene oxides: Bandgap engineering of phosphorene by oxidation

    NASA Astrophysics Data System (ADS)

    Ziletti, A.; Carvalho, A.; Trevisanutto, P. E.; Campbell, D. K.; Coker, D. F.; Castro Neto, A. H.

    2015-02-01

    We show that oxidation of phosphorene can lead to the formation of a new family of planar (two-dimensional) and tubular (one-dimensional) oxides and suboxides, most of them insulating. This confers to black phosphorus a native oxide that can be used as barrier material and protective layer. Furthermore, the bandgap of phosphorene oxides depends on the oxygen concentration, suggesting that controlled oxidation can be used as a means to engineer the bandgap. For the oxygen saturated composition, P2O5 , both the planar and tubular phases have a large bandgap energy of about 8.5 eV and are transparent in the near UV. These two forms of phosphorene oxides are predicted to have the same formation enthalpy as O'-P2O5 , the most stable of the previously known forms of phosphorus pentoxide.

  6. Oxidative stress and oxidative damage in chemical carcinogenesis

    SciTech Connect

    Klaunig, James E., E-mail: jklauni@indiana.edu; Wang Zemin; Pu Xinzhu; Zhou Shaoyu

    2011-07-15

    Reactive oxygen species (ROS) are induced through a variety of endogenous and exogenous sources. Overwhelming of antioxidant and DNA repair mechanisms in the cell by ROS may result in oxidative stress and oxidative damage to the cell. This resulting oxidative stress can damage critical cellular macromolecules and/or modulate gene expression pathways. Cancer induction by chemical and physical agents involves a multi-step process. This process includes multiple molecular and cellular events to transform a normal cell to a malignant neoplastic cell. Oxidative damage resulting from ROS generation can participate in all stages of the cancer process. An association of ROS generation and human cancer induction has been shown. It appears that oxidative stress may both cause as well as modify the cancer process. Recently association between polymorphisms in oxidative DNA repair genes and antioxidant genes (single nucleotide polymorphisms) and human cancer susceptibility has been shown.

  7. Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

    Microsoft Academic Search

    R. S. Roth; W. S. Brower; H. S. Parker; D. B. Minor; J. L. Waring

    1975-01-01

    The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and

  8. Methanol oxidation over nonprecious transition metal oxide catalysts

    Microsoft Academic Search

    Umit S. Ozkan; Richard F. Kueller; Edgar Moctezuma

    1990-01-01

    This paper reports methanol oxidation over nonprecious transition metal oxide catalysts studied in a gradient less external recycle reactor. The catalysts (oxides of Cr, Mn, Fe, Co, Ni, Cu), which were prepared by using the incipient wetness technique, were supported on 1\\/8 in.γ-AlâOâ tablets. The catalysts were characterized by using BET surface area measurement, X-ray diffraction, laser Raman spectroscopy, scanning

  9. Oxidation kinetics of aluminum nitride at different oxidizing atmosphere

    Microsoft Academic Search

    Xinmei Hou; Kuo-Chih Chou; Xiangchong Zhong; Seshadri Seetharaman

    2008-01-01

    In the present work, the oxidation kinetics of AlN powder was investigated by using thermogravimetric analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experiments were carried out both in isothermal as well as non-isothermal modes under two different oxidizing atmospheres. The results showed that the oxidation reaction started at around 1100K and the rate increased significantly beyond 1273K

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

    Microsoft Academic Search

    Seiichiro Imamura; Ikumi Fukuda; Shingo Ishida

    1988-01-01

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

  11. Unusual inherent electrochemistry of graphene oxides prepared using permanganate oxidants.

    PubMed

    Eng, Alex Yong Sheng; Ambrosi, Adriano; Chua, Chun Kiang; San?k, Filip; Sofer, Zden?k; Pumera, Martin

    2013-09-16

    Graphene and graphene oxides are materials of significant interest in electrochemical devices such as supercapacitors, batteries, fuel cells, and sensors. Graphene oxides and reduced graphenes are typically prepared by oxidizing graphite in strong mineral acid mixtures with chlorate (Staudenmaier, Hofmann) or permanganate (Hummers, Tour) oxidants. Herein, we reveal that graphene oxides pose inherent electrochemistry, that is, they can be oxidized or reduced at relatively mild potentials (within the range ±1 V) that are lower than typical battery potentials. This inherent electrochemistry of graphene differs dramatically from that of the used oxidants. Graphene oxides prepared using chlorate exhibit chemically irreversible reductions, whereas graphene oxides prepared through permanganate-based methods exhibit very unusual inherent chemically reversible electrochemistry of oxygen-containing groups. Insight into the electrochemical behaviour was obtained through cyclic voltammetry, chronoamperometry, and X-ray photoelectron spectroscopy experiments. Our findings are of extreme importance for the electrochemistry community as they reveal that electrode materials undergo cyclic changes in charge/discharge cycles, which has strong implications for energy-storage and sensing devices. PMID:23934966

  12. Oxidation resistant alloys, method for producing oxidation resistant alloys

    SciTech Connect

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

    2002-11-05

    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

  13. Role of oxidative stress and nitric oxide in atherothrombosis

    PubMed Central

    Lubos, Edith; Handy, Diane E.; Loscalzo, Joseph

    2008-01-01

    During the last decade basic and clinical research has highlighted the central role of reactive oxygen species (ROS) in cardiovascular disease. Enhanced production or attenuated degradation of ROS leads to oxidative stress, a process that affects endothelial and vascular function, and contributes to vascular disease. Nitric oxide (NO), a product of the normal endothelium, is a principal determinant of normal endothelial and vascular function. In states of inflammation, NO production by the vasculature increases considerably and, in conjunction with other ROS, contributes to oxidative stress. This review examines the role of oxidative stress and NO in mechanisms of endothelial and vascular dysfunction with an emphasis on atherothrombosis. PMID:18508590

  14. Zinc oxide varistors and/or resistors

    DOEpatents

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

    1993-01-01

    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.

  15. Zinc oxide varistors and/or resistors

    DOEpatents

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

    1993-07-27

    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.

  16. Mesoporous mn- and la-doped cerium oxide/cobalt oxide mixed metal catalysts for methane oxidation.

    PubMed

    Vickers, Susan M; Gholami, Rahman; Smith, Kevin J; MacLachlan, Mark J

    2015-06-01

    New precious-metal-free mesoporous materials were investigated as catalysts for the complete oxidation of methane to carbon dioxide. Mesoporous cobalt oxide was first synthesized using KIT-6 mesoporous silica as a hard template. After removal of the silica, the cobalt oxide was itself used as a hard template to construct cerium oxide/cobalt oxide composite materials. Furthermore, cerium oxide/cobalt oxide composite materials doped with manganese and lanthanum were also prepared. All of the new composite materials retained the hierarchical long-range order of the original KIT-6 template. Temperature-programmed oxidation measurements showed that these cerium oxide/cobalt oxide and doped cerium oxide/cobalt oxide materials are effective catalysts for the total oxidation of methane, with a light-off temperature (T50%) of ?400 °C observed for all of the nanostructured materials. PMID:26000732

  17. Correlated Oxide Physics and Electronics

    NASA Astrophysics Data System (ADS)

    Ngai, J. H.; Walker, F. J.; Ahn, C. H.

    2014-07-01

    Transition metal oxides exhibit a range of correlated phenomena with applications to novel electronic devices that possess remarkable functionalities. This article reviews recent progress in elucidating both mechanisms that govern correlated behavior in transition metal oxides and advancements in device fabrication that have enabled strong correlations to be controlled through applied electric fields. Advancements in the growth of transition-metal-oxide films and artificial heterostructures have enabled superconductivity, magnetism, and metal-insulator transitions to be controlled in cuprates, manganites, and vanadates by using the electric field effect. In addition, interfaces between transition metal oxides have recently emerged as a setting in which strong correlations can be manipulated in two dimensions to realize unusual quantum-ordered phases. Finally, key relationships between structure and transport in ultrathin films of transition metal oxides have been elucidated. Coupling the structural degrees of freedom in oxides to applied electric fields thus opens new pathways to control correlated behavior in devices.

  18. Microbial Hydrocarbon Co-oxidation

    PubMed Central

    Raymond, R. L.; Jamison, V. W.; Hudson, J. O.

    1967-01-01

    Nocardia cultures, isolated from soil by use of n-paraffins as the sole carbon source, have been shown to bring about significant oxidation of several methyl-substituted mono- and dicyclic aromatic hydrocarbons. Oxygen uptake by washed cell suspensions was not a reliable indicator of oxidation. Under co-oxidation conditions in shaken flasks, o- and p-xylenes were oxidized to their respective mono-aromatic acids, o-toluic and p-toluic acids. In addition, a new fermentation product, 2, 3-dihydroxy-p-toluic acid, was found in the p-xylene oxidation system. Of 10 methyl-substituted naphthalenes tested (1-methyl, 2-methyl, 1, 3-dimethyl, 1, 4-dimethyl, 1, 5-dimethyl, 1, 8-dimethyl, 1, 6-dimethyl, 2, 3-dimethyl, 2, 6-dimethyl, 2, 7-dimethyl), only those containing a methyl group in the ? position were oxidized at this position to the mono acid. PMID:6049305

  19. Stratospheric sulfur oxidation kinetics

    SciTech Connect

    Jayne, J.T.; Worsnop, D.R.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States)] [and others

    1995-12-31

    Oxidation of SO2 to H2SO4 in the atmosphere is believed to involve the reaction of SO3 with water. It is commonly assumed that this is an important step leading to homogeneous nucleation of H2SO4 aerosol particles. Heterogeneous chemistry on sulfuric acid aerosols regulate much of the ozone photochemistry in the lower stratosphere and are also believed to have significant effect on the climate. Understanding aerosol loading requires a detailed knowledge of the stratospheric sulfur budget, including its oxidation kinetics. Here we present results of a laboratory project studying a key step in the oxidation process, the homogeneous reaction between SO3 and H2O vapor. Kinetic measurements are performed in a high-pressure turbulent fast-flow reactor (fabricated at MIT) which minimizes heterogeneous loss of SO3 on reactorwalls. The rate of decay of SO3 and the appearance of H2SO4 is monitored in the presence of excess water vapor. Gas phase reactants and products are detected via an atmospheric pressure chemical ionization mass spectrometer which is coupled to the exit of the flow reactor. Sulfuric acid nucleation studies can also be performed using the turbulent flow reactor. Initial measurements using a particle detector (based on Mie scattering) showed that aerosol formation and particle size distribution are controlled by varying the SO3/H2O gas ratio and the reactor temperature. Results for the reaction SO3J+ H2O show a second order dependence in water vapor density and a strong negative temperature dependence. The results, measured in the range -30C to +95C, imply that an SO3.H2O adduct and/or a water dimer species is likely involved in the reaction mechanism. Results of recent theoretical calculations on the SO3 + H2O system also support the finding that two water molecules are involved. Implications for the gas phase production of sulfuric acid in the atmosphere will be discussed.

  20. Selective oxidations by nitrosating agents

    Microsoft Academic Search

    N. C. Marziano; L. Ronchin; C. Tortato; S. Ronchin; A. Vavasori

    2005-01-01

    The reactivity of a nitrosating agent (N2O3) on oxidations of alcohols and the methyl group of acetophenone were tested. Active electrophylic surface nitrosonium ions (NO+) was detected on H2SO4\\/SiO2 catalysts by Raman spectroscopy, suggesting a surface ionic mechanism of oxidation in agreement with the one proposed in acid aqueous solutions. Alcohols are selectively oxidized to ketones and aldehydes in high

  1. Amorphous transition metal oxide films

    Microsoft Academic Search

    Neil Heiman; N. S. Kazama

    1979-01-01

    We have been able to prepare amorphous oxides of Fe and Cr by sputter deposition. Magnetization measurements were made between 4.2 K and 300 K. Mössbauer spectra were obtained for the iron oxide samples in the same temperature range. Amorphous CrO2 films showed no evidence of magnetic order. For the amorphous Fe oxide films, the 4.2 K Mössbauer spectrum showed

  2. Solid oxide electrochemical reactor science

    Microsoft Academic Search

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

    2010-01-01

    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

  3. Semiconducting transition metal oxides

    NASA Astrophysics Data System (ADS)

    Lany, Stephan

    2015-07-01

    Open shell transition metal oxides are usually described as Mott or charge transfer insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a correlated gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g. for energy applications. In order to place the 3d orbitals and the sp bands into an integrated picture, band structure calculations should treat both contributions on the same footing and, at the same time, account fully for electron correlation in the 3d shell. Fundamentally, this is a rather daunting task for electronic structure calculations, but quasi-particle energy calculations in GW approximation offer a viable approach for band structure predictions in these materials. Compared to conventional semiconductors, the inherent multivalent nature of transition metal cations is more likely to cause undesirable localization of electron or hole carriers. Therefore, a quantitative prediction of the carrier self-trapping energy is essential for the assessing the semiconducting properties and to determine whether the transport mechanism is a band-like large-polaron conduction or a small-polaron hopping conduction. An overview is given for the binary 3d oxides on how the hybridization between the 3d crystal field symmetries with the O-p orbitals of the ligands affects the effective masses and the likelihood of electron and hole self-trapping, identifying those situations where small masses and band-like conduction are more likely to be expected. The review concludes with an illustration of the implications of the increased electronic complexity of transition metal cations on the defect physics and doping, using as an example the diversity of possible atomic and magnetic configurations of the O vacancy in TiO2, and the high levels of hole doping in Co2ZnO4 due to a self-doping mechanism that originates from the multivalence of Co.

  4. Semiconducting transition metal oxides.

    PubMed

    Lany, Stephan

    2015-07-22

    Open shell transition metal oxides are usually described as Mott or charge transfer insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a correlated gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g. for energy applications. In order to place the 3d orbitals and the sp bands into an integrated picture, band structure calculations should treat both contributions on the same footing and, at the same time, account fully for electron correlation in the 3d shell. Fundamentally, this is a rather daunting task for electronic structure calculations, but quasi-particle energy calculations in GW approximation offer a viable approach for band structure predictions in these materials. Compared to conventional semiconductors, the inherent multivalent nature of transition metal cations is more likely to cause undesirable localization of electron or hole carriers. Therefore, a quantitative prediction of the carrier self-trapping energy is essential for the assessing the semiconducting properties and to determine whether the transport mechanism is a band-like large-polaron conduction or a small-polaron hopping conduction. An overview is given for the binary 3d oxides on how the hybridization between the 3d crystal field symmetries with the O-p orbitals of the ligands affects the effective masses and the likelihood of electron and hole self-trapping, identifying those situations where small masses and band-like conduction are more likely to be expected. The review concludes with an illustration of the implications of the increased electronic complexity of transition metal cations on the defect physics and doping, using as an example the diversity of possible atomic and magnetic configurations of the O vacancy in TiO2, and the high levels of hole doping in Co2ZnO4 due to a self-doping mechanism that originates from the multivalence of Co. PMID:26126022

  5. Oxidizing Borcherds symmetries

    E-print Network

    Axel Kleinschmidt; Jakob Palmkvist

    2013-01-07

    The tensor hierarchy of maximal supergravity in D dimensions is known to be closely related to a Borcherds (super)algebra that is constructed from the global symmetry group E(11-D). We here explain how the Borcherds algebras in different dimensions are embedded into each other and can be constructed from a unifying Borcherds algebra. The construction also has a natural physical explanation in terms of oxidation. We then go on to show that the Hodge duality that is present in the tensor hierarchy has an algebraic counterpart. For D>8 the Borcherds algebras we find differ from the ones existing in the literature although they generate the same tensor hierarchy.

  6. Nitrogen Oxide Calculator

    NSDL National Science Digital Library

    Pratte, John

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

  7. Metabolism of Nitrogen Oxides in Ammonia-Oxidizing Bacteria

    NASA Astrophysics Data System (ADS)

    Kozlowski, J.; Stein, L. Y.

    2014-12-01

    Ammonia-oxidizing bacteria (AOB) are key microorganisms in the transformation of nitrogen intermediates in most all environments. Until recently there was very little work done to elucidate the physiology of ammonia-oxidizing bacteria cultivated from variable trophic state environments. With a greater variety of ammonia-oxidizers now in pure culture the importance of comparative physiological and genomic analysis is crucial. Nearly all known physiology of ammonia-oxidizing bacteria lies within the Nitrosomonas genus with Nitrosomonas europaea strain ATCC 19718 as the model. To more broadly characterize and understand the nature of obligate ammonia chemolithotrophy and the contribution of AOB to production of nitrogen oxides, Nitrosomonas spp. and Nitrosospira spp. isolated from variable trophic states and with sequenced genomes, were utilized. Instantaneous ammonia- and hydroxylamine-oxidation kinetics as a function of oxygen and substrate concentration were measured using an oxygen micro-sensor. The pathway intermediates nitric oxide and nitrous oxide were measured in real time using substrate-specific micro-sensors to elucidate whether production of these molecules is stoichiometric with rates of substrate oxidation. Genomic inventory was compared among the strains to identify specific pathways and modules to explain physiological differences in kinetic rates and production of N-oxide intermediates as a condition of their adaptation to different ammonium concentrations. This work provides knowledge of how nitrogen metabolism is differentially controlled in AOB that are adapted to different concentrations of ammonium. Overall, this work will provide further insight into the control of ammonia oxidizing chemolithotrophy across representatives of the Nitrosomonas and Nitrosospira genus, which can then be applied to examine additional genome-sequenced AOB isolates.

  8. Oxidation resistant coatings for molybdenum

    SciTech Connect

    Timmons, G.A.

    1988-05-17

    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.

  9. Operation of staged membrane oxidation reactor systems

    DOEpatents

    Repasky, John Michael

    2012-10-16

    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.

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

    E-print Network

    Sparks, Donald L.

    OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty All Rights Reserved #12;OXIDATION AND SORPTION KINETICS OF ARSENIC ON A POORLY CRYSTALLINE MANGANESE OXIDE by Brandon J. Lafferty Approved

  11. Iron Oxide Based High Temperature Desulfurization Sorbent

    Microsoft Academic Search

    Ju Shangguan; Pengfei Hou; Yongjun Zhu; Litong Liang; Fang Shen; Huiling Fan; Maoqian Miao

    2009-01-01

    Iron oxide sorbent is used as high temperature desulfurization sorbent due to high sulfur capacity, easy regeneration and recovery elemental sulfur. In this paper, the iron oxide based high-temperature sorbent was obtained by mixing iron oxide with calcium oxide, extrudating and calcinating. The sulfidation, reduction and regeneration performance for the prepared iron oxide based desulfurization sorbent were conducted. The phases

  12. High temperature oxidation resistant cermet compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (inventor)

    1976-01-01

    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.

  13. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, J.L.; Chenghung Hung.

    1993-12-07

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

  14. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, Joseph L. (Baltimore, MD); Hung, Cheng-Hung (Baltimore, MD)

    1993-01-01

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

  15. Pristine graphite oxide.

    PubMed

    Dimiev, Ayrat; Kosynkin, Dmitry V; Alemany, Lawrence B; Chaguine, Pavel; Tour, James M

    2012-02-01

    Graphite oxide (GO) is a lamellar substance with an ambiguous structure due to material complexity. Recently published GO-related studies employ only one out of several existing models to interpret the experimental data. Because the models are different, this leads to confusion in understanding the nature of the observed phenomena. Lessening the structural ambiguity would lead to further developments in functionalization and use of GO. Here, we show that the structure and properties of GO depend significantly on the quenching and purification procedures, rather than, as is commonly thought, on the type of graphite used or oxidation protocol. We introduce a new purification protocol that produces a product that we refer to as pristine GO (pGO) in contrast to the commonly known material that we will refer to as conventional GO (cGO). We explain the differences between pGO and cGO by transformations caused by reaction with water. We produce ultraviolet-visible spectroscopic, Fourier transform infrared spectroscopic, solid-state nuclear magnetic resonance spectroscopic, thermogravimetric, and scanning electron microscopic analytical evidence for the structure of pGO. This work provides a new explanation for the acidity of GO solutions and allows us to add critical details to existing GO models. PMID:22239610

  16. Nanoporous silicon oxide memory.

    PubMed

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

    2014-08-13

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

  17. Oxidants, oxidative stress and the biology of ageing

    Microsoft Academic Search

    Toren Finkel; Nikki J. Holbrook

    2000-01-01

    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.

  18. Self-assembled zinc oxide nanodots on silicon oxide

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, K.; Boukos, N.; Travlos, A.

    2005-01-01

    Self assembled ZnO nanodots are grown by electron beam evaporation of Zn on thermally oxidized silicon substrates and subsequent annealing in oxygen. Characterization by TEM and EELS shows that the quantum dots are indeed zinc oxide single crystals grown with their c-axis perpendicular to the substrate; their distribution and size depends on the deposition parameters of zinc onto the substrates.

  19. Coal oxidation and calcium loading on oxidized coal

    Microsoft Academic Search

    Eung Ha Cho; Qiuliang Luo

    1996-01-01

    A Pittsburgh No. 8 coal, and two IBC (Illinois Basin Coal) 101 and 112 coals were oxidized in a 2 1 Parr Stirred Bench Top Reactor. The oxidation time was varied up to 5 h; the temperature from 150°C to 225°C, the oxygen pressure from 100 to 600 psi, and coal dosage from 15 to 60 g in 600 ml

  20. The oxidation behavior of Co15 wt % Cr alloy containing dispersed oxides formed by internal oxidation

    Microsoft Academic Search

    P. Y. Hou; Z. R. Shui; J. Stringer

    1991-01-01

    Internal oxidation pretreatments of Co-15wt%Cr and Co-15wt%Cr-1wt%Ti were carried out using a Rhines pack in quartz, in mullite and in alumina. A dispersion of titanium oxide particles formed in the Ti-containing alloy as a result of the internal oxidation. However, silicon also diffused into all treated specimens when the pretreatments were carried out in quartz or in mullite. The effect

  1. Mechanism of selective oxidation of methanol over stannic oxide-molybdenum oxide catalyst

    Microsoft Academic Search

    V Locha?; J Machek; J Tichý

    2002-01-01

    The mechanism of the selective oxidation of methanol on Sn-Mo oxide catalyst with molar ratio Mo\\/(Mo+Sn)=0.3 is investigated. The interaction of methanol and its oxidation products (i.e. formaldehyde and methyl formate) is studied by FT-IR spectroscopy. The data are interpreted on the basis of a reaction mechanism which contains 10 elementary steps. The behaviors of the surface species (methoxy, formate

  2. Kinetics of propylene oxidation on multicomponent oxide catalyst

    SciTech Connect

    Boreskov, G.K.; Erenburg, E.M.; Andrushkevich, T.V.; Zelenkova, T.V.; Bibin, V.N.; Meshcheryakov, V.D.; Boronina, N.P.; Tyurin, Y.N.

    1983-02-01

    A kinetic study of propylene oxidation on a multicomponent molybdenum-containing oxide catalyst has been carried out in a circulating-flow unit in the temperature interval 573-663/sup 0/K. The dependences of the reaction product formation rates (acrolein, acrylic acid, acetic acid, CO, and CO/sub 2/) are described by equations that are first-order with respect to the substance being oxidized, these equations differing in the influence of acrolein and water. The conversion of propylene to acrolein is an autocatalytic reaction accelerated by acrolein. Water vapor increases the acid formation and suppresses the reactions of exhaustive oxidation of acrolein and acetic acid, without affecting the post-oxidation of acrylic acid. Kinetic equations are proposed for all of the partial reactions. Nonlinear programming has been used to calculate the constants of the equations and the activation energies.

  3. P-31 / Schlott P-31: Nodule Formation on Indium-Oxide Tin-Oxide

    E-print Network

    P-31 / Schlott P-31: Nodule Formation on Indium-Oxide Tin-Oxide Sputtering Targets M. Schlott, M from indium-oxide tin-oxide (ITO) targets [1]. Unfor- tunately, black growths, or nodules, commonly isostatic pressing partly reduced powder mixtures of 90 wt.% indium-oxide and 10 wt.% tin-oxide [4

  4. Radiation hardness of fluorinated oxides prepared by liquid phase deposition method following rapid thermal oxidation

    Microsoft Academic Search

    Wei-Shin Lu; Jenq-Shiuh Chou; Si-Chen Lee; Jenn-Gwo Hwu

    1994-01-01

    Liquid phase deposition (LPD following rapid thermal oxidation 2 RTO) is proposed as a method to obtain the fluorinated gate oxides. The radiation effect on these fluorinated oxides prepared by various sequences is studied. It was experimentally observed that all the fluorinated gate oxides are more radiation hard than the rapid thermal oxide (control oxide). Interestingly, the amount of fluorine

  5. Nitric oxide and asthmatic inflammation

    Microsoft Academic Search

    Peter J. Barnes; F. Y. Liew

    1995-01-01

    Asthmatic patients show an increased expression of inducible nitric oxide synthase (iNOS) in airway epithelial cells and an increased level of nitric oxide (NO) in exhaled air. The NO derived from airway epithelial cells may be a mechanism for amplifying and perpetuating asthmatic inflammation, through inhibition of T helper 1 (Th1) cells and their production of interferon ? (IFN-?). This

  6. Cation ordering in complex oxides

    Microsoft Academic Search

    Peter K. Davies

    1999-01-01

    Several recent papers have addressed the fundamental aspects of the stability and kinetics of ordering in complex oxides, and investigated systems where the properties are mediated by the degree of order. Cation ordering reactions have been shown to induce large alterations in the dielectric, ferroelectric, magnetic, and electronic response of many complex oxides. The majority of the cited publications focus

  7. Oxide Fiber Targets at ISOLDE

    Microsoft Academic Search

    U Köster; U C Bergmann; D Carminati; R Catherall; J Cederkäll; J G Correia; B Crepieux; M Dietrich; K Elder; V Fedosseev; L M Fraile-Prieto; S Franchoo; H O U Fynbo; U Georg; T Giles; A Joinet; O C Jonsson; R Kirchner; C Lau; Jacques Lettry; H J Maier; V I Mishin; M Oinonen; K Peräjärvi; H L Ravn; T Rinaldi; M Santana-Leitner; U Wahl; L Weissman

    2002-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxyde fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxyde fiber targets (titania, zirconia, ceria and thoria) used

  8. Metal oxide nanowires gas sensors

    Microsoft Academic Search

    E. Comini

    2008-01-01

    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

  9. ENGINEERING BULLETIN: CHEMICAL OXIDATION TREATMENT

    EPA Science Inventory

    Oxidation destroys hazardous contaminants by chemically converting them to nonhazardous or less toxic compounds that are ideally more stable, less mobile, and/or inert. However, under some conditions, other hazardous compounds may be formed. The oxidizing agents most commonly use...

  10. Automated analysis of oxidative metabolites

    NASA Technical Reports Server (NTRS)

    Furner, R. L. (inventor)

    1974-01-01

    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.

  11. Detection of oxidation in human serum lipoproteins 

    E-print Network

    Myers, Christine Lee

    2006-04-12

    A method for the oxidation of lipoproteins in vitro was developed using the free radical initiator, 2,2?-azobis-(2-amidinopropane) dihydrochloride (AAPH). Following in vitro oxidation, the susceptibility to oxidation of the serum samples...

  12. 49 CFR 173.337 - Nitric oxide.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2 2011-10-01 2011-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Gases; Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to...

  13. 49 CFR 173.337 - Nitric oxide.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 2 2013-10-01 2013-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Gases; Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to...

  14. 49 CFR 173.337 - Nitric oxide.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 2 2014-10-01 2014-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Gases; Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to...

  15. 49 CFR 173.337 - Nitric oxide.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 2 2012-10-01 2012-10-01 false Nitric oxide. 173.337 Section 173.337 Transportation...Gases; Preparation and Packaging § 173.337 Nitric oxide. (a) Nitric oxide must be packaged in cylinders conforming to...

  16. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

  17. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

  18. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

  19. EFFECTS OF PHOTOCHEMICAL OXIDANTS ON PLANTS

    EPA Science Inventory

    Photochemical oxidants are found in 'photochemical smog' which is a complex mixture of primary and secondary air pollutants. The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarbons, their precursors. Th...

  20. Catalyst for Decomposition of Nitrogen Oxides

    NASA Technical Reports Server (NTRS)

    Schryer, David R. (Inventor); Jordan, Jeffrey D. (Inventor); Akyurtlu, Ates (Inventor); Akyurtlu, Jale (Inventor)

    2015-01-01

    This invention relates generally to a platinized tin oxide-based catalyst. It relates particularly to an improved platinized tin oxide-based catalyst able to decompose nitric oxide to nitrogen and oxygen without the necessity of a reducing gas.

  1. 21 CFR 73.3125 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125...CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No....

  2. 21 CFR 177.1620 - Polyethylene, oxidized.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...the mild air oxidation of polyethylene conforming to the density...1520(c). Such oxidized polyethylene has a minimum number average...chapter may be corrected for wax, petrolatum, and mineral...not applicable to oxidized polyethylene used as provided in §§...

  3. 21 CFR 177.1620 - Polyethylene, oxidized.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...the mild air oxidation of polyethylene conforming to the density...1520(c). Such oxidized polyethylene has a minimum number average...chapter may be corrected for wax, petrolatum, and mineral...not applicable to oxidized polyethylene used as provided in §§...

  4. Nitric oxide and pulmonary hypertension

    PubMed Central

    2010-01-01

    Pulmonary hypertension is a serious complication of a number of lung and heart diseases that is characterized by peripheral vascular structural remodeling and loss of vascular tone. Nitric oxide can modulate vascular injury and interrupt elevation of pulmonary vascular resistance selectively; however, it can also produce cytotoxic oxygen radicals and exert cytotoxic and antiplatelet effects. The balance between the protective and adverse effects of nitric oxide is determined by the relative amount of nitric oxide and reactive radicals. Nitric oxide has been shown to be clinically effective in the treatment of congenital heart disease, mitrial valvular disease combined with pulmonary hypertension and in orthotropic cardiac transplantation patients. Additionally, new therapeutic modalities for the treatment of pulmonary hypertension, phosphodiesterase inhibitors, natriuretic peptides and aqueous nitric oxide are also effective for treatment of elevated pulmonary vascular resistance. PMID:20498805

  5. Stabilization of elusive silicon oxides

    NASA Astrophysics Data System (ADS)

    Wang, Yuzhong; Chen, Mingwei; Xie, Yaoming; Wei, Pingrong; Schaefer, Henry F.; Schleyer, Paul Von R.; Robinson, Gregory H.

    2015-06-01

    Molecular SiO2 and other simple silicon oxides have remained elusive despite the indispensable use of silicon dioxide materials in advanced electronic devices. Owing to the great reactivity of silicon–oxygen double bonds, as well as the low oxidation state of silicon atoms, the chemistry of simple silicon oxides is essentially unknown. We now report that the soluble disilicon compound, L:Si=Si:L (where L:?=?:C{N(2,6-iPr2C6H3)CH}2), can be directly oxidized by N2O and O2 to give the carbene-stabilized Si2O3 and Si2O4 moieties, respectively. The nature of the silicon oxide units in these compounds is probed by spectroscopic methods, complementary computations and single-crystal X-ray diffraction.

  6. Ultra Supercritical Steamside Oxidation

    SciTech Connect

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

    2005-01-01

    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.

  7. Oxidation And Hot Corrosion Of ODS Alloy

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.

    1993-01-01

    Report reviews oxidation and hot corrosion of oxide-dispersion-strengthened (ODS) alloys, intended for use at high temperatures. Classifies environmental resistances of such alloys by rates of growth of oxides, volatilities of oxides, spalling of oxides, and limitations imposed by hot corrosion. Also discusses environmentally resistant coatings for ODS materials. Concludes ODS NICrAl and FeCrAl alloys highly resistant to oxidation and corrosion and can be used uncoated.

  8. Nanowire-based All Oxide Solar Cells

    Microsoft Academic Search

    Benjamin D. Yuhas; Peidong; Peidong Yang

    2008-01-01

    We present an all-oxide solar cell fabricated from vertically oriented zinc oxide nanowires and cuprous oxide nanoparticles. Our solar cell consists of vertically oriented n-type zinc oxide nanowires, surrounded by a film constructed from p-type cuprous oxide nanoparticles. Our solution-based synthesis of inexpensive and environmentally benign oxide materials in a solar cell would allow for the facile production of large-scale

  9. Pomegranate juice protects nitric oxide against oxidative destruction and enhances the biological actions of nitric oxide

    Microsoft Academic Search

    Louis J. Ignarro; Russell E. Byrns; Daigo Sumi; Filomena de Nigris; Claudio Napoli

    2006-01-01

    Pomegranate juice (PJ), which is a rich source of potent flavonoid antioxidants, was tested for its capacity to protect nitric oxide (NO) against oxidative destruction and enhance the biological actions of NO. Employing chemiluminescence headspace analysis, PJ was found to be a potent inhibitor of superoxide anion-mediated disappearance of NO. PJ was much more potent than Concord grape juice, blueberry

  10. Thermal Oxidation of Aluminum Nitride Powder

    SciTech Connect

    Gu, Zheng; Edgar, James H.; Wang, Chong M.; Coffey, Dorothy

    2006-07-31

    The kinetics of the thermal oxidation of AlN powder in flowing oxygen over temperatures from 800 to 1150 C and the morphology and crystallinity of the resultant oxide were determined. The oxidation of two types of AlN powder was investigated and compared. Complex difference in the oxidation behavior was observed, probably due to their different morphology, particle size, particle size distribution, and residual impurities. Amorphous alumina formed at relatively low oxidation temperatures (800-1000 C), with a linear oxidation rate governed by interfacial reaction. Crystalline alumina formed at higher temperatures (>1000 C), and the oxidation rate was parabolic which suggested an oxidant diffusion controlled process.

  11. Simulation and comparative study on the oxidation kinetics of atrazine by UV/H2O2, UV/HSO5(-) and UV/S2O8(2.).

    PubMed

    Luo, Congwei; Ma, Jun; Jiang, Jin; Liu, Yongze; Song, Yang; Yang, Yi; Guan, Yinghong; Wu, Daoji

    2015-09-01

    This study comparatively investigated atrazine (ATZ) degradation by irradiation at the wavelength of 254 nm in the presence of peroxides including hydrogen peroxide (H2O2), peroxymonosulfate (HSO5(-)), and persulfate (S2O8(2-)) at various initial ATZ concentrations and oxidant dosages. The effects of water matrix, such as carbonate/bicarbonate (HCO3(-)/CO3(2-)), chloride ions (Cl(-)), and natural organic matter (NOM), were evaluated on these three advanced oxidation processes. A simple steady-state kinetic model was developed based on the initial rates of ATZ destruction, which could well describe the apparent pseudo-first-order rate constants (kapp, s(-1)) of ATZ degradation in these three processes. The specific roles of reactive species (i.e., HO, SO4(-), CO3(-), and Cl2(-)) under various experimental conditions were quantitatively evaluated based on their steady-state concentrations obtained from this model. Modeling results showed that the steady-state concentrations of HO and SO4(-) decreased with the increase of CO3(2-)/HCO3(-) concentration, and the relative contribution of HO to ATZ degradation significantly decreased in UV/H2O2 and UV/HSO5(-) systems. On the other hand, the scavenging effect of HCO3(-)/CO3(2-) on the relative contribution of SO4(-) to ATZ degradation was lower than that on HO. The presence of Cl(-) (0.5-10 mM) significantly scavenged SO4(-) but had slightly scavenging effect on HO at the present experimental pH, resulting in greater decrease of kapp in the UV/S2O8(2-) than UV/H2O2 and UV/HSO5(-) systems. Higher levels of Cl2(-) were generated in the UV/S2O8(2-) than those in the UV/H2O2 and UV/HSO5(-) systems at the same Cl(-) concentrations. NOM significantly decreased kapp due to its effects of competitive UV absorption and radical scavenging with the latter one being dominant. These results improve the understanding of the effects of water constituents for ATZ degradation in the UV-based oxidation processes. PMID:25996757

  12. Uranium Metal to Oxide Conversion by Air Oxidation ?Process Development

    SciTech Connect

    Duncan, A

    2001-12-31

    Published technical information for the process of metal-to-oxide conversion of uranium components has been reviewed and summarized for the purpose of supporting critical decisions for new processes and facilities for the Y-12 National Security Complex. The science of uranium oxidation under low, intermediate, and high temperature conditions is reviewed. A process and system concept is outlined and process parameters identified for uranium oxide production rates. Recommendations for additional investigations to support a conceptual design of a new facility are outlined.

  13. Ethanol oxidation on metal oxide-supported platinum catalysts

    SciTech Connect

    L. M. Petkovic 090468; Sergey N. Rashkeev; D. M. Ginosar

    2009-09-01

    Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on Ethanol is a renewable fuel that can be used as an additive to gasoline (or its substitute) with the advantage of octane enhancement and reduced carbon monoxide exhaust emissions. However, on the standard three-way catalysts, the conversion of unburned ethanol is low because both ethanol and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.and some of its partially oxidized derivatives are highly resistant to oxidation. A combination of first-principles density-functional theory (DFT) based calculations and in-situ diffuse reflectance infrared spectroscopy (DRIFTS) analysis was applied to uncover some of the fundamental phenomena associated with ethanol oxidation on Pt containing catalysts. In particular, the objective was to analyze the role of the oxide (i.e., ?-Al2O3 or SiO2) substrate on the ethanol oxidation activity. The results showed that Pt nanoparticles trap and accumulate oxygen at their surface and perimeter sites and play the role of “stoves” that burn ethanol molecules and their partially oxidized derivatives to the “final” products. The ?-Al2O3 surfaces provided higher mobility of the fragments of ethanol molecules than the SiO2 surface and hence increased the supply rate of these objects to the Pt particles. This will in turn produce a higher conversion rate of unburned ethanol.

  14. Status of Graphite Oxidation Work

    SciTech Connect

    Rebecca Smith

    2010-05-01

    Data were developed to compare the extent of structural damage associated with high temperature exposure to an air leak. Two materials, NBG-18 graphite and unpurified PCEA graphite have been tested as of this report. The scope was limited to isothermal oxidation at a single temperature, 750°C. Ambient post-oxidation compression strength testing was performed for three levels of burn off (1%, 5%, and 10% mass loss) for two leak scenarios: 100% air and 10% air in helium. Temperature, gas flow, and dynamic mass loss oxidation conditions were monitored and recorded for each sample. The oxidation period was controlled with flow of inert gas during the thermal ramp and upon cool down with a constant 10 liter per minute flow maintained throughout furnace operation. Compressive strengths of parallel un-oxidized samples were tested to assess the relative mass loss effects. In addition to baseline samples matching the un-oxidized dimensions of the oxidized samples, two sets of mechanically reduced samples were prepared. One set was trimmed to achieve the desired mass loss by removing an effectively uniform depth from the geometric surface of the sample. The other set was cored to produce a full penetration axial hole down the center of each sample.

  15. The oxidation of Fe(111)

    NASA Astrophysics Data System (ADS)

    Davies, Robert; Edwards, Dyfan; Gräfe, Joachim; Gilbert, Lee; Davies, Philip; Hutchings, Graham; Bowker, Michael

    2011-09-01

    The oxidation of Fe(111) was studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), ion scattering spectroscopy (ISS) and scanning tunnelling microscopy (STM). Oxidation of the crystal was found to be a very fast process, even at 200 K, and the Auger O signal saturation level is reached within ~ 50 × 10 - 6 mbar s. Annealing the oxidised surface at 773 K causes a significant decline in apparent surface oxygen concentration and produces a clear (6 × 6) LEED pattern, whereas after oxidation at ambient temperature no pattern was observed. STM results indicate that the oxygen signal was reduced due to the nucleation of large, but sparsely distributed oxide islands, leaving mainly the smooth (6 × 6) structure between the islands. The reactivity of the (6 × 6) layer towards methanol was investigated using temperature programmed desorption (TPD), which showed mainly decomposition to CO and CO 2, due to the production of formate intermediates on the surface. Interestingly, this removes the (6 × 6) structure by reduction, but it can be reformed from the sink of oxygen present in the large oxide islands simply by annealing at 773 K for a few minutes. The (6 × 6) appears to be a relatively stable, pseudo-oxide phase, that may be useful as a model oxide surface.

  16. Mammalian mitochondrial beta-oxidation.

    PubMed Central

    Eaton, S; Bartlett, K; Pourfarzam, M

    1996-01-01

    The enzymic stages of mammalian mitochondrial beta-oxidation were elucidated some 30-40 years ago. However, the discovery of a membrane-associated multifunctional enzyme of beta-oxidation, a membrane-associated acyl-CoA dehydrogenase and characterization of the carnitine palmitoyl transferase system at the protein and at the genetic level has demonstrated that the enzymes of the system itself are incompletely understood. Deficiencies of many of the enzymes have been recognized as important causes of disease. In addition, the study of these disorders has led to a greater understanding of the molecular mechanism of beta-oxidation and the import, processing and assembly of the beta-oxidation enzymes within the mitochondrion. The tissue-specific regulation, intramitochondrial control and supramolecular organization of the pathway is becoming better understood as sensitive analytical and molecular techniques are applied. This review aims to cover enzymological and organizational aspects of mitochondrial beta-oxidation together with the biochemical aspects of inherited disorders of beta-oxidation and the intrinsic control of beta-oxidation. PMID:8973539

  17. Catastrophic Oxidation of Copper: A Brief Review

    NASA Astrophysics Data System (ADS)

    Belousov, V. V.; Klimashin, A. A.

    2012-10-01

    A brief review of the current understanding of copper accelerated oxidation in the presence of low-melting oxides (Bi2O3, MoO3, and V2O5) is given. Special attention is paid to the kinetics, thermodynamics, and mechanisms of accelerated oxidation of copper. The mechanisms of two stages (fast and superfast) of the copper accelerated oxidation are considered. It is shown that the fast oxidation of copper occurs by a diffusion mechanism. Oxygen diffusion along the liquid channels in the oxide scale is the rate-limiting step in the overall mechanism. The superfast oxidation of copper occurs by a fluxing mechanism. Realization of the particular mechanism depends on the mass ratio of low-melting oxide to the metal. The mass ratios of low-melting oxide to the metal and the oxygen partial pressures for superfast oxidation of copper are established. A model of the fast oxidation of copper is discussed.

  18. Thermally oxidized zinc oxide nanowires for use as chemical sensors.

    PubMed

    Zappa, D; Comini, E; Sberveglieri, G

    2013-11-01

    Zinc oxide (ZnO) mat-based conductometric devices were fabricated using a thermal oxidation technique. A metallic zinc layer was deposited on the alumina transducer and then oxidized in a controlled atmosphere, in order to obtain ZnO nanostructures. Two different batches of sensors have been prepared, and their sensing performances have been evaluated towards oxidizing and reducing gases. Functional measurements showed very good sensing performances towards ethanol and acetone at 500 °C, and NO2 at 200 °C, indirectly confirming the n-type behaviour of the material. The influence of the humidity on the response has been explored. In practical conditions the interference of humidity is very small, and could be neglected in many applications. Simultaneous measurements on different devices from the same batch confirm the high reproducibility of the response within the batch. PMID:24113169

  19. Intracellular oxidation of hydroethidine: compartmentalization and cytotoxicity of oxidation products.

    PubMed

    Lyublinskaya, O G; Zenin, V V; Shatrova, A N; Aksenov, N D; Zemelko, V I; Domnina, A P; Litanyuk, A P; Burova, E B; Gubarev, S S; Negulyaev, Y A; Nikolsky, N N

    2014-10-01

    Hydroethidine (HE) is a blue fluorescent dye that is intracellularly converted into red-emitting products on two-electron oxidation. One of these products, namely 2-hydroxyethidium, is formed as the result of HE superoxide anion-specific oxidation, and so HE is widely used for the detection of superoxide in cells and tissues. In our experiments we exploited three cell lines of different origin: K562 (human leukemia cells), A431 (human epidermoid carcinoma cells), and SCE2304 (human mesenchymal stem cells derived from endometrium). Using fluorescent microscopy and flow cytometry analysis, we showed that HE intracellular oxidation products accumulate mostly in the cell mitochondria. This accumulation provokes gradual depolarization of mitochondrial membrane, affects oxygen consumption rate in HE-treated cells, and causes cellular apoptosis in the case of high HE concentrations and/or long cell incubations with HE, as well as a high rate of HE oxidation in cells exposed to some stimuli. PMID:25035077

  20. IRON OXIDE NANOPARTICLE-INDUCED OXIDATIVE STRESS AND INFLAMMATION

    EPA Science Inventory

    Nanoparticle Physicochemical Characterizations We first focused on creating NP systems that could be used to test our hypotheses and assessing their stability in aqueous media. The iron oxide NP systems were not stable in cell culture medium o...

  1. Oxidative demethylation of 2-picolines on vanadium oxide catalysts

    SciTech Connect

    Suvorov, B.V.; Glubokovskikh, L.K.; Demin, V.V.; Kan, I.I.

    1988-07-10

    One of the known methods for the preparation of pyridine is based on the dealkylation of alkylpyridines in the presence of vanadium-containing catalysts, molecular oxygen and steam. By using the oxidative demethylation of 2-picoline in the presence of steam on a fused vanadium(V) oxide, pyridine can be obtained in a yield of up to 88% of theory. To lower the consumption of vanadium(V) oxide and increase the thermostability of the catalyst, they studied the possible use of V/sub 2/O/sub 5/ catalysts on various carriers (diatomite, silica gel, porcelain balls), including the industrially produced brand SVD and SVS catalysts. The SVS brand catalyst has a satisfactory activity and selectivity in the oxidation demethylation of 2-picoline into pyridine. Under optimal conditions, pyridine is formed on this catalyst in a yield of 88% of the theoretical.

  2. Oxidative coupling of methane in a solid oxide membrane reactor

    SciTech Connect

    Guo, X.M.; Hidajat, K.; Ching, C.B. [National Univ. of Singapore (Singapore). Dept. of Chemical Engineering; Chen, H.F. [Tianjin Univ. (China). Dept. of Chemical Engineering

    1997-09-01

    The oxidative coupling of methane (OCM) has been studied using the 1 wt% Sr/La{sub 2}O{sub 3}-Bi{sub 2}O{sub 3}-Ag-YSZ solid oxide membrane reactor. The effects of oxygen flux, temperature and feed concentration on the performance of oxidative coupling of methane reaction have been investigated. Two mathematical models based on well-mixed flow (CSTM) or plug flow (PFM) in the reactor have been developed to describe the behavior of the solid oxide membrane reactors. The simulation results show good agreement with experimental data. However, the simulation results of the CSTM fit experimental data much better than that of PFM over a broad range of experimental conditions. The simulation results also show it is very important to match reaction conditions and reactor parameters.

  3. Graphene oxide aerogel-supported Pt electrocatalysts for methanol oxidation

    NASA Astrophysics Data System (ADS)

    Duan, Jialin; Zhang, Xuelin; Yuan, Weijian; Chen, Hailong; Jiang, Shan; Liu, Xiaowei; Zhang, Yufeng; Chang, Limin; Sun, Zhiyuan; Du, Juan

    2015-07-01

    Graphene oxide aerogel (GOA) was prepared to serve as catalyst support for Pt nanoparticles for methanol electro-oxidation. Analyses by X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to physically characterize the Pt/GOA catalyst. The results show that Pt/GOA has a 3D macroporous structure, which can not only accelerate mass transfer but also provide a larger efficient surface area for methanol oxidation. The results of electrochemical tests reveal that Pt/GOA has an electrochemical surface area as large as 95.5 m2 g-1, and its peak current density toward methanol oxidation is as high as 876 mA mg-1Pt.

  4. Detailed mechanism of benzene oxidation

    NASA Technical Reports Server (NTRS)

    Bittker, David A.

    1987-01-01

    A detailed quantitative mechanism for the oxidation of benzene in both argon and nitrogen diluted systems is presented. Computed ignition delay time for argon diluted mixtures are in satisfactory agreement with experimental results for a wide range of initial conditions. An experimental temperature versus time profile for a nitrogen diluted oxidation was accurately matched and several concentration profiles were matched qualitatively. Application of sensitivity analysis has given approximate rate constant expressions for the two dominant heat release reactions, the oxidation of C6H5 and C5H5 radicals by molecular oxygen.

  5. Epitaxial magnetic oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Belenky, Land J.

    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 of substrates to achieve well-defined surfaces at the atomic level and the development of a deposition and analysis technique capable of controlling growth' at this level. We have used a pulsed laser deposition system with in situ reflection high-energy electron diffraction to produce epitaxial magnetic oxide heterostructures on lattice-matched substrates and have investigated a number of magnetic interactions. We have demonstrated an unusual antiferromagnetic interfacial exchange coupling between epitaxial bilayers of La0.67Sr0.33MnO 3 and SrRuO3 grown on (001) SrTiO3 substrates. The sign and magnitude of the exchange field depends on the cooling field. By interrupting the charge transfer at the interface with a very thin insulating layer, we have demonstrated this exchange biasing effect is related to the spin-dependent band structures of the materials. We have investigated the structural and magnetic properties of epitaxial multilayers and superlattices of manganites. These materials exhibit colossal magnetoresistance and the Curie temperature can be adjusted over a range of 100 K. We have fabricated La0.67Sr0.33MnO3/La 0.82Ba0.18MnO3 superlattices with layers as thin as 8 unit cells (32A). These superlattices have magnetic transition temperatures above 350 K and coercivities of approximately 10 Oe. Deposition techniques can effectively control the out-of-plane dimension on the nanoscale but control or lateral dimensions has proven more challenging. We have fabricated magnetic perovskite nanodots less than 50 nm tall with diameters less than 100 nm using electron-beam lithography and ion milling. The nanodots maintain their crystallinity, epitaxial structure and ferromagnetic properties. These are the smallest ferromagnetic perovskite nanodots yet reported. This work helps understanding in the issues relating the processing and growth of perovskite heterostructures to physical phenomenon.

  6. Tryptophan oxidation in proteins exposed to thiocyanate-derived oxidants.

    PubMed

    Bonifay, Vincent; Barrett, Tessa J; Pattison, David I; Davies, Michael J; Hawkins, Clare L; Ashby, Michael T

    2014-12-15

    Human defensive peroxidases, including lactoperoxidase (LPO) and myeloperoxidase (MPO), are capable of catalyzing the oxidation of halides (X(-)) by H2O2 to give hypohalous acids (HOX) for the purpose of cellular defense. Substrate selectivity depends upon the relative abundance of the halides, but the pseudo-halide thiocyanate (SCN(-)) is a major substrate, and sometimes the exclusive substrate, of all defensive peroxidases in most physiologic fluids. The resulting hypothiocyanous acid (HOSCN) has been implicated in cellular damage via thiol oxidation. While thiols are believed to be the primary target of HOSCN in vivo, Trp residues have also been implicated as targets for HOSCN. However, the mechanism involved in HOSCN-mediated Trp oxidation was not established. Trp residues in proteins appeared to be susceptible to oxidation by HOSCN, whereas free Trp and Trp residues in small peptides were found to be unreactive. We show that HOSCN-induced Trp oxidation is dependent on pH, with oxidation of free Trp, and Trp-containing peptides observed when the pH is below 2. These conditions mimic those employed previously to precipitate proteins after treatment with HOSCN, which accounts for the discrepancy in the results reported for proteins versus free Trp and small peptides. The reactant in these cases may be thiocyanogen ((SCN)2), which is produced by comproportionation of HOSCN and SCN(-) at low pH. Reaction of thiocyanate-derived oxidants with protein Trp residues at low pH results in the formation of a number of oxidation products, including mono- and di-oxygenated derivatives, which are also formed with other hypohalous acids. Our data suggest that significant modification of Trp by HOSCN in vivo is likely to have limited biological relevance. PMID:25172223

  7. Oxidation of nitric oxide by a new heterotrophic Pseudomonas sp

    Microsoft Academic Search

    Matthias Koschorreck; Edward Moore; Ralf Conrad

    1996-01-01

    A new bacterial strain isolated from soil consumed nitric oxide (NO) under oxic conditions by oxidation to nitrate. Phenotypic\\u000a and phylogenetic characterization of the new strain PS88 showed that it represents a previously unknown species of the genus\\u000a Pseudomonas, closely related to Pseudomonas fluorescens and Pseudomonas putida. The heterotrophic, obligately aerobic strain PS88 was not able to denitrify or nitrify;

  8. Indirect oxidation effect in electrochemical oxidation treatment of landfill leachate

    Microsoft Academic Search

    Li-Choung Chiang; Juu-En Chang; Ten-Chin Wen

    1995-01-01

    Treatment of a low BODCOD ratio landfill leachate was conducted by means of electrochemical oxidation process in this investigation. Under the operating conditions of 15 A\\/dm2 current density and 7500 mg\\/l additional chloride concentration, 92% of the COD in the landfall leachate was removed after electrolysis for 240 min with a ternary Sn?Pd?Ru oxide-coated titanium (SPR) anode. At the same

  9. Alkali oxide-tantalum, niobium and antimony oxide ionic conductors

    NASA Technical Reports Server (NTRS)

    Roth, R. S.; Brower, W. S.; Parker, H. S.; Minor, D. B.; Waring, J. L.

    1975-01-01

    The phase equilibrium relations of four systems were investigated in detail. These consisted of sodium and potassium antimonates with antimony oxide and tantalum and niobium oxide with rubidium oxide as far as the ratio 4Rb2O:llB2O5 (B=Nb, Ta). The ternary system NaSbO3-Sb2O4-NaF was investigated extensively to determine the actual composition of the body centered cubic sodium antimonate. Various other binary and ternary oxide systems involving alkali oxides were examined in lesser detail. The phases synthesized were screened by ion exchange methods to determine mobility of the mobility of the alkali ion within the niobium, tantalum or antimony oxide (fluoride) structural framework. Five structure types warranted further investigation; these structure types are (1) hexagonal tungsten bronze (HTB), (2) pyrochlore, (3) the hybrid HTB-pyrochlore hexagonal ordered phases, (4) body centered cubic antimonates and (5) 2K2O:3Nb2O5. Although all of these phases exhibit good ion exchange properties only the pyrochlore was prepared with Na(+) ions as an equilibrium phase and as a low porosity ceramic. Sb(+3) in the channel interferes with ionic conductivity in this case, although relatively good ionic conductivity was found for the metastable Na(+) ion exchanged analogs of RbTa2O5F and KTaWO6 pyrochlore phases.

  10. Atomic layer deposition of tin oxide with nitric oxide as an oxidant gas Jaeyeong Heo, Sang Bok Kim and Roy G. Gordon*

    E-print Network

    Atomic layer deposition of tin oxide with nitric oxide as an oxidant gas Jaeyeong Heo, Sang Bok Kim and nitric oxide (NO) as an oxidant gas. Film properties as a function of growth temperature from 130­250 C report that nitric oxide (NO) can be used as an effective oxidant gas with this Sn(II) precursor

  11. Chemiluminescence of nitric oxide

    NASA Technical Reports Server (NTRS)

    Sharp, W. E.; Rusch, D. W.

    1981-01-01

    Measurements of the intensities of the delta and gamma bands of nitric oxide in the nighttime terrestrial thermosphere are presented and used to infer the rate coefficient for the transition from the C 2 Pi to the A 2 Sigma + states. The nightglow spectrum was observed between 1900 and 2300 A at a resolution of 15 A by a rocket-borne scanning 1/4-m spectrometer pointing north at an apogee of 150 km. Progressions of the delta, gamma and epsilon bands are identified on the spectra by the construction of synthetic spectra, and the contributions of resonance fluorescence to the total band intensities are calculated. Finally, the ratio of the sum of the gamma bands for v-prime = 0 to the sum of the delta bands for v-prime = 0 is used to derive a branching ratio of 0.21 + or - 0.04 to the A 2 Sigma + state, which yields a probability for the C-A transition of 5.6 + or - 1.5 x to the 6th/sec.

  12. Placental nitric oxide metabolism.

    PubMed

    Sooranna, S R; Morris, N H; Steer, P J

    1995-01-01

    There is increasing evidence that nitric oxide (NO) has a role in pregnancy. NO is synthesized from L-arginine by NO synthase (NOS), which can exist either as a calcium-dependent or a calcium-independent isoform of the enzyme. Both isoforms are present in placental villi and the authors have measured NOS activities in tissues from early and term normal, pre-eclamptic and growth-retarded pregnancies. Higher activities were seen in first trimester placental villi than at term. An impairment of NO metabolism occurred in placental villi from pre-eclamptic and growth-retarded pregnancies. Smoking also results in decreased NOS activities in the placental villi, suggesting that problems attributed to smoking during pregnancy could be linked to NO metabolism. Polyamines arginine and citrulline (all of which are important metabolites in the NO pathway) were also measured in placental villous tissues. The data presented in this review article are from work carried out in the authors' laboratories and suggest that alterations in the placental arginine-NO pathway may not only play a role in the physiological changes of advancing gestation but may also contribute to the pathophysiology of pre-eclampsia and fetal growth retardation. PMID:8743159

  13. Aluminium oxide microchannel plates

    NASA Astrophysics Data System (ADS)

    Delendik, K.; Emeliantchik, I.; Litomin, A.; Rumyantsev, V.; Voitik, O.

    2003-09-01

    Microchannel electron multipliers of a new type are proposed - anodic alumina microchannel plates (MCP). They implement the conventional concept of lead glass microchannel plate with a new material - anodic aluminium oxide. Anodic alumina is a very suitable material for microchannel plates due to presense of natural microchannels. Diameters of these channels lie in the range of 0.02 - 0.5 ?m, channels of greater diameter can be easily produced by means of additional processing based on the presence of intrinsic microchannel structure. We have produced MCPs with channel diameters 0.2 - 8 ?m and thickness 40 - 150 ?m. We have also developed two methods of deposition of conductive and emissive films inside MCP channels: plasma sputtering and liquid-phase deposition from metallo-organic precursors. MCP samples with NiO?MgO and Cu?CuO?BeO?MgO coatings have demonstrated promising results. Alumina MCP potentially have serious advantages over traditional lead glass MCP: they are much cheaper, large area plates (hundreds of cm2) can be easily produced, spatial resolution can be much better (due to smaller channel diameter).

  14. COPD: balancing oxidants and antioxidants

    PubMed Central

    Fischer, Bernard M; Voynow, Judith A; Ghio, Andrew J

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most common chronic illnesses in the world. The disease encompasses emphysema, chronic bronchitis, and small airway obstruction and can be caused by environmental exposures, primarily cigarette smoking. Since only a small subset of smokers develop COPD, it is believed that host factors interact with the environment to increase the propensity to develop disease. The major pathogenic factors causing disease include infection and inflammation, protease and antiprotease imbalance, and oxidative stress overwhelming antioxidant defenses. In this review, we will discuss the major environmental and host sources for oxidative stress; discuss how oxidative stress regulates chronic bronchitis; review the latest information on genetic predisposition to COPD, specifically focusing on oxidant/antioxidant imbalance; and review future antioxidant therapeutic options for COPD. The complexity of COPD will necessitate a multi-target therapeutic approach. It is likely that antioxidant supplementation and dietary antioxidants will have a place in these future combination therapies. PMID:25673984

  15. Thermal oxidation procedure PREPARATION........................................................................................................................................... 2

    E-print Network

    Hochberg, Michael

    ....................................................................................................... 2 Step 2 Power up the furnace..................................................... 9 Equipment: Thermco TMX 9002 Cooling Water Control Panel Computer Furnace Switch Furnace 1 Furnace 2 Furnace 3 Furnace 4 Gas routing Measure the thinkneess here Lamp & blower #12;Thermal oxidation

  16. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    EPA Science Inventory

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. his information is provided to assist remedial project managers, contractors ...

  17. ENGINEERING BULLETIN: SUPERCRITICAL WATER OXIDATION

    EPA Science Inventory

    This engineering bulletin presents a description and status of supercritical water oxidation technology, a summary of recent performance tests, and the current applicability of this emerging technology. This information is provided to assist remedial project managers, contractors...

  18. METHANE OXIDATION (AEROBIC) Helmut Brgmann

    E-print Network

    Wehrli, Bernhard

    ; Madigan et al., 2003; Bowman, 2006). The process is performed by a specialized group of bacteria (qv) (Madigan et al., 2003). Thus, aerobic methane oxidation can be considered a special case of aerobic ADP ATP

  19. Electrostatic doping in oxide heterostructures

    NASA Astrophysics Data System (ADS)

    Lee, Jaekwang; Demkov, Alexander A.

    2008-03-01

    Recent experiments on perovskite heterostructures grown by molecular beam epitaxy or pulsed laser deposition suggest the possibility of creating high mobility two dimensional electron gas at the oxide/oxide interface. However, the origin of charge in these insulating materials is still not clear and deemed controversial. We report a first-principles study of SrTiO3/LaAlO3 heterostructures using density functional theory at the LDA+U level. We consider the energetics and electronic structure of the junction, while focusing on the role of electrostatics. Our results suggest that a complex balance of the crystal filed, Jahn-Teller effect, lattice dynamics and internal electric field result in the robust electrostatic doping for carefully chosen thickness of the polar oxide. We explore the possible uses of this effect in other oxide-based heterostructures.

  20. Nitric Oxide-Releasing Compounds

    NSDL National Science Digital Library

    The five WebWare Molecules for December derive from the article Nitrogen-Based Diazeniumdiolates: Versatile Nitric Oxide-Releasing Compounds for Biomedical Research and Potential Clinical Applications by Joseph E. Saavedra and Larry K. Keefer.

  1. The catalytic oxidation of propane 

    E-print Network

    Sanderson, Charles Frederick

    1949-01-01

    stepwise, the pro? ducts in the successive steps being, respectively, alcohol, aldehyde, acid, carbon oxides and water. The single greatest argument against this theory was the fact that workers, up to that time, had failed to detect methanol... that the surface effects emphasized the 11 probability of a chain mechanism* Newitt and his co-workers (9) (10) (11) (12) duplicated and extended the earlier work of Pease in mapping the cool flame-ignition temperatu.re-pressure areas in the oxidation...

  2. Magnetite Oxidation: A Proposed Mechanism.

    PubMed

    Colombo, U; Gazzarrini, F; Lanzavecchia, G; Sironi, G

    1965-02-26

    All magnetites are oxidized topotactically with formation of solid solution at temperatures below 400 degrees C. The oxidation of hematite-free magnetites proceeds to gammaFe(2)O(3), whereas in the presence of hematite epitaxial growth of alphaFe(2)O(3) takes place, with excess iron ions being returned to the solid solution. A method for synthesizing maghemite from natural magnetites is indicated. PMID:17813310

  3. Zinc oxide nanoparticles on silicon

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, K.; Boukos, N.; Travlos, A.

    2006-01-01

    Self-assembled ZnO nanoparticles are grown by electron beam evaporation of Zn on silicon oxide and silicon substrates and subsequent annealing in oxygen. Characterization by TEM and EELS shows that the nanoparticles can be zinc oxide single crystals grown with their c-axis perpendicular to the substrate; their distribution, size and crystallinity depend on the deposition parameters of zinc and the growth substrate. We discuss the effect of these parameters on the morphology of the resulting material.

  4. Thermal oxidation of carbon nanomaterials

    NASA Astrophysics Data System (ADS)

    Glebova, N. V.; Nechitailov, A. A.; Kukushkina, Yu. A.; Sokolov, V. V.

    2011-05-01

    The process of the thermal oxidation of various carbon nanomaterials (multiwalled carbon nanotubes, carbon black, nanoporous carbon and graphite) used in the catalytic layers of electrochemical energy converters (electrolyzers, fuel cells) has been studied. The thermal stability of these materials has been determined. Relationships between the structural characteristics of carbon nanomaterials and the parameters of their thermal oxidation in air have determined using the methods of differential thermal analysis and adsorption-structure analysis.

  5. Oxidative Stress and Atrial Fibrillation

    Microsoft Academic Search

    Ali A. Sovari; Samuel C. Dudley

    \\u000a The pathological processes involved in initiation and perpetuation of atrial fibrillation (AF) are still unclear. AF is associated\\u000a with systemic and cardiac oxidative stress and inflammation. Many risk factors for AF, such as aging and diabetes, are associated\\u000a with an increased level of reactive oxygen species. In addition, oxidative stress has been shown at both cellular and tissue\\u000a levels to

  6. Nitrous Oxide Transport and Transformation

    NSDL National Science Digital Library

    Pierre-Andre Jacinthe

    In this laboratory exercise, students add nitrous oxide to pairs of undisturbed soil cores. One core in each set of cores is treated with acetylene to block nitrous oxide transformation. The bulk of this exercise involves, injection and drawing of air samples. Students gain experience manipulating gas concentration data, determining soil properties related to transport of gases through porous medium like soils. This exercise is appropriate for soil physics and biogeochemistry courses.

  7. Main group chemistry: Small silicon oxides isolated

    NASA Astrophysics Data System (ADS)

    Apeloig, Yitzhak

    2015-06-01

    Bulk SiO2 is widespread in nature, and silicon oxide clusters are important to a variety of applications, yet molecular silicon oxides have remained elusive. Two molecular compounds featuring silicon oxide moieties, Si2O3 and Si2O4, have now been isolated by oxidation of a carbene-stabilized disilicon precursor.

  8. Measurement of Oxide Adherence to PFM Alloys

    Microsoft Academic Search

    J. R. Mackert; E. E. Parry Jr; D. T. Hashinger; C. W. Fairhurst

    1984-01-01

    A method has been reported for evaluating adherence of an oxide to its substrate metal to a maximum value of about 40 MPa. Oxidized alloy plates were cemented between two aluminum cylinders with a high-strength cyanoacrylate cement and loaded in tension until failure occurred either at the oxide\\/metal interface, within the oxide layer, or in the cement itself. Significant differences

  9. Metal oxide nanostructures with hierarchical morphology

    DOEpatents

    Ren, Zhifeng (Newton, MA); Lao, Jing Yu (Saline, MI); Banerjee, Debasish (Ann Arbor, MI)

    2007-11-13

    The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

  10. Oxidative desulphurization study of gasoline and kerosene

    Microsoft Academic Search

    M. Shakirullah; Waqas Ahmad; Imtiaz Ahmad; M. Ishaq

    2010-01-01

    Desulphurization of gasoline and kerosene was carried out using organic and inorganic oxidants. Among the organic oxidants used were hydrogen peroxide in combination with acetic acid, formic acid, benzoic acid and butyric acid, while inorganic oxidants used included potassium permanganate and sodium perchlorate. The oxidation of each petroleum oil was carried out in two steps; the first step consisted of

  11. Methane oxidation over dual redox catalysts

    Microsoft Academic Search

    K. Klier; R. G. Herman; Z. Sojka; J. I. DiCosimo; S. DeTavernier

    1992-01-01

    Catalytic oxidation of methane to partial oxidation products, primarily formaldehyde and C[sub 2] hydrocarbons, was found to be directed by the catalyst used. In this project, it was discovered that a moderate oxidative coupling catalyst for C[sub 2] hydrocarbons, zinc oxide, is modified by addition of small amounts of Cu and Fe dopants to yield fair yields of formaldehyde. A

  12. Solid oxide fuel cell matrix and modules

    Microsoft Academic Search

    Riley

    1990-01-01

    This patent describes a modular solid oxide fuel cell arrangement. It comprises: a solid oxide fuel cell having an anode, a cathode and a solid electrolyte therebetween and responsive to an oxidant and a fuel gas provided thereto for converting chemical energy of the fuel gas to direct current electrical energy; and block means coupled to the solid oxide fuel

  13. The metabolomics of oxidative stress.

    PubMed

    Noctor, Graham; Lelarge-Trouverie, Caroline; Mhamdi, Amna

    2015-04-01

    Oxidative stress resulting from increased availability of reactive oxygen species (ROS) is a key component of many responses of plants to challenging environmental conditions. The consequences for plant metabolism are complex and manifold. We review data on small compounds involved in oxidative stress, including ROS themselves and antioxidants and redox buffers in the membrane and soluble phases, and we discuss the wider consequences for plant primary and secondary metabolism. While metabolomics has been exploited in many studies on stress, there have been relatively few non-targeted studies focused on how metabolite signatures respond specifically to oxidative stress. As part of the discussion, we present results and reanalyze published datasets on metabolite profiles in catalase-deficient plants, which can be considered to be model oxidative stress systems. We emphasize the roles of ROS-triggered changes in metabolites as potential oxidative signals, and discuss responses that might be useful as markers for oxidative stress. Particular attention is paid to lipid-derived compounds, the status of antioxidants and antioxidant breakdown products, altered metabolism of amino acids, and the roles of phytohormone pathways. PMID:25306398

  14. Accelerated oxidation processes is biodiesel

    SciTech Connect

    Canakci, M.; Monyem, A.; Van Gerpen, J.

    1999-12-01

    Biodiesel is an alternative fuel for diesel engines that can be produced from renewable feedstocks such as vegetable oil and animal fats. These feedstocks are reacted with an alcohol to produce alkyl monoesters that can be used in conventional diesel engines with little or no modification. Biodiesel, especially if produced from highly unsaturated oils, oxidizes more rapidly than diesel fuel. This article reports the results of experiments to track the chemical and physical changes that occur in biodiesel as it oxidizes. These results show the impact of time, oxygen flow rate, temperature, metals, and feedstock type on the rate of oxidation. Blending with diesel fuel and the addition of antioxidants are explored also. The data indicate that without antioxidants, biodiesel will oxidize very quickly at temperatures typical of diesel engines. This oxidation results in increases in peroxide value, acid value, and viscosity. While the peroxide value generally reaches a plateau of about 350 meq/kg ester, the acid value and viscosity increase monotonically as oxidation proceeds.

  15. Nitric oxide as an antioxidant

    SciTech Connect

    Kanner, J.; Harel, S.; Granit, R. (Department of Food Science, Volcani Center, Bet Dagan (Israel))

    1991-08-15

    Benzoate monohydroxy compounds, and in particular salicylate, were produced during interaction of ferrous complexes with hydrogen peroxide (Fenton reaction) in a N2 environment. These reactions were inhibited when Fe complexes were flushed, prior to the addition in the model system, by nitric oxide. Methionine oxidation to ethylene by Fenton reagents was also inhibited by nitric oxide. Myoglobin in several forms such as metmyoglobin, oxymyoglobin, and nitric oxide-myoglobin were interacted with an equimolar concentration of hydrogen peroxide. Spectra changes in the visible region and the changes in membrane (microsomes) lipid peroxidation by the accumulation of thiobarbituric acid-reactive substances (TBA-RS) were determined. The results showed that metmyoglobin and oxymyoglobin were activated by H2O2 to ferryl myoglobin, which initiates membrane lipid peroxidation; but not nitric oxide-myoglobin, which, during interaction with H2O2, did not form ferryl but metmyoglobin which only poorly affected lipid peroxidation. It is assumed that nitric oxide, liganded to ferrous complexes, acts to prevent the prooxidative reaction of these complexes with H2O2.

  16. Electrostatic doping in oxide heterostructures.

    NASA Astrophysics Data System (ADS)

    Demkov, Alexander A.; Lee, Jaekwang; Sai, Na

    2009-03-01

    Recent experiments on perovskite heterostructures grown by methods ranging from molecular beam epitaxy to pulsed laser deposition suggest the existence of two dimensional electron gas of high mobility at the oxide/oxide interface, and even a possibility of a superconducting state. Both p-type and n-type interfaces have been reported. However, the origin of charge in these insulating materials is still under debate. We report a first-principles study of several heterostructures where we employ the internal filed in a polar oxide LaAlO3 to demonstrate the possibility of the electrostatic doping, an effect similar to a well known polar catastrophe in e.g., III-V semiconductors. We use density functional theory at the LDA+U level. We mainly focus on the electronic structure of the oxide/oxide junctions. The results of our calculations suggest that once the critical thickness of the aluminate layer is reached the internal electric field is sufficient to produce the electrostatic doping. We will discuss simple estimates for the temperature of the superconducting transition and the role of oxygen-related defects such as vacancies in the electronic structure and thermodynamic stability of these fascinating oxide structures.

  17. Enhanced colonic nitric oxide generation and nitric oxide synthase activity in ulcerative colitis and Crohn's disease

    Microsoft Academic Search

    D Rachmilewitz; J S Stamler; D Bachwich; F Karmeli; Z Ackerman; D K Podolsky

    1995-01-01

    Recent studies have suggested that nitric oxide (NO.), the product of nitric oxide synthase in inflammatory cells, may play a part in tissue injury and inflammation through its oxidative metabolism. In this study the colonic generation of oxides of nitrogen (NOx) and nitric oxide synthase activity was determined in ulcerative colitis and Crohn's disease. Colonic biopsy specimens were obtained from

  18. Study of Growth Characteristics and Interfaces of Oxides and Oxide-Metal Heterostructures

    Microsoft Academic Search

    Sailaja Yadavalli

    1992-01-01

    Single crystal films of oxides have been synthesized by molecular beam epitaxy using methods developed in this thesis research and the growth characteristics of oxides and oxide-metal heterostructures have been studied. Studies of the structure of the oxide-metal interfaces using x -ray diffraction spectroscopy and high resolution electron microscopy are presented. The surface structure of the oxide and metal films

  19. Molecules of Interest Nitric oxide and nitric oxide synthase activity in plants

    E-print Network

    Wurtele, Eve Syrkin

    Molecules of Interest Nitric oxide and nitric oxide synthase activity in plants Luis A. del Ri in plants are nitrate reductase, and several nitric oxide synthase-like activities, including one localized. # 2004 Elsevier Ltd. All rights reserved. Keywords: Nitrogen monoxide; Nitric oxide; NO; Nitric oxide

  20. Metal Oxide Composite Enabled Nanotextured Si Photoanode for Efficient Solar Driven Water Oxidation

    E-print Network

    Wang, Deli

    Metal Oxide Composite Enabled Nanotextured Si Photoanode for Efficient Solar Driven Water Oxidation oxide composite modified n-Si photoanode for efficient and stable water oxidation. This sputter of operation, the oxide composite provides a simple method to enable unstable photoanode materials for solar

  1. Oxidation effect on templating of metal oxide nanoparticles within block copolymers

    E-print Network

    Kofinas, Peter

    Oxidation effect on templating of metal oxide nanoparticles within block copolymers Pinar Akcora a-norbornene dicarboxylic acid) (NOR-NORCOOH) have been synthesized and processed to template metal oxide nanoparticle) copolymer films before and after oxidizing the metal ions into metal oxides. The carboxylic acid containing

  2. Theoretical model for the anodic oxidation of organics on metal oxide electrodes

    Microsoft Academic Search

    O. Simond; V. Schaller; Ch. Comninellis

    1997-01-01

    A theoretical model describing the electrochemical oxidation of organics at oxide electrodes (MOx) forming the higher oxide (MOx+1) is described. In this model both organics oxidation and O2 evolution are mediated by the higher oxide (MOx+1) which is electrogenerated at the anode surface. The effect of concentration polarization in the electrolyte is also included in the theoretical model.

  3. Oxidative stress and hypertension.

    PubMed

    Harrison, David G; Gongora, Maria Carolina

    2009-05-01

    This review has summarized some of the data supporting a role of ROS and oxidant stress in the genesis of hypertension. There is evidence that hypertensive stimuli, such as high salt and angiotensin II, promote the production of ROS in the brain, the kidney, and the vasculature and that each of these sites contributes either to hypertension or to the untoward sequelae of this disease. Although the NADPH oxidase in these various organs is a predominant source, other enzymes likely contribute to ROS production and signaling in these tissues. A major clinical challenge is that the routinely used antioxidants are ineffective in preventing or treating cardiovascular disease and hypertension. This is likely because these drugs are either ineffective or act in a non-targeted fashion, such that they remove not only injurious ROS Fig. 5. Proposed role of T cells in the genesis of hypertension and the role of the NADPH oxidase in multiple cells/organs in modulating this effect. In this scenario, angiotensin II stimulates an NADPH oxidase in the CVOs of the brain, increasing sympathetic outflow. Sympathetic nerve terminals in lymph nodes activate T cells, and angiotensin II also directly activates T cells. These stimuli also activate expression of homing signals in the vessel and likely the kidney, which attract T cells to these organs. T cells release cytokines that stimulate the vessel and kidney NADPH oxidases, promoting vasoconstriction and sodium retention. SFO, subfornical organ. 630 Harrison & Gongora but also those involved in normal cell signaling. A potentially important and relatively new direction is the concept that inflammatory cells such as T cells contribute to hypertension. Future studies are needed to understand the interaction of T cells with the CNS, the kidney, and the vasculature and how this might be interrupted to provide therapeutic benefit. PMID:19427495

  4. Method for plating with metal oxides

    DOEpatents

    Silver, G.L.; Martin, F.S.

    1994-08-23

    A method is disclosed of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate. 1 fig.

  5. Method for plating with metal oxides

    DOEpatents

    Silver, Gary L. (Centerville, OH); Martin, Frank S. (Farmersville, OH)

    1994-08-23

    A method of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate.

  6. Nitroxide-Functionalized Graphene Oxide from Graphite Oxide

    PubMed Central

    Avila-Vega, Yazmin I.; Leyva-Porras, Cesar C.; Mireles, Marcela; Quevedo-López, Manuel; Macossay, Javier; Bonilla-Cruz, José

    2013-01-01

    A facile method for preparing functionalized graphene oxide single layers with nitroxide groups is reported herein. Highly oxidized graphite oxide (GO=90.6%) was obtained, slightly modifying an improved Hummer’s method. Oxoammonium salts (OS) were investigated to introduce nitroxide groups to GO, resulting in a one-step functionalization and exfoliation. The mechanisms of functionalization/exfoliation are proposed, where the oxidation of aromatic alcohols to ketone groups, and the formation of alkoxyamine species are suggested. Two kinds of functionalized graphene oxide layers (GOFT1 and GOFT2) were obtained by controlling the amount of OS added. GOFT1 and GOFT2 exhibited a high interlayer spacing (d0001 = 1.12nm), which was determined by X-ray diffraction. The presence of new chemical bonds C-N (~9.5 %) and O-O (~4.3 %) from nitroxide attached onto graphene layers were observed by X-ray photoelectron spectroscopy. Single-layers of GOFT1 were observed by HRTEM, exhibiting amorphous and crystalline zones at a 50:50 ratio; in contrast, layers of GOFT2 exhibited a fully amorphous surface. Fingerprint of GOFT1 single layers was obtained by electron diffraction at several tilts. Finally, the potential use of these materials within Nylon 6 matrices was investigated, where an unusual simultaneous increase in tensile stress, tensile strain and Young’s modulus was observed. PMID:24347671

  7. Modeling of surface oxidation and oxidation induced damage in metal matrix composites 

    E-print Network

    Ma, Xinzheng

    1995-01-01

    Surface oxidation in metal matrix composites (MMC's) is modeled by Fickian diffusion of oxygen in both the oxide layer and metal matrix. The oxidation process and the resulting immobilized oxygen at the interface is accounted for by the introduction...

  8. Modeling of surface oxidation and oxidation induced damage in metal matrix composites

    E-print Network

    Ma, Xinzheng

    1995-01-01

    Surface oxidation in metal matrix composites (MMC's) is modeled by Fickian diffusion of oxygen in both the oxide layer and metal matrix. The oxidation process and the resulting immobilized oxygen at the interface is accounted for by the introduction...

  9. In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM

    E-print Network

    Dunin-Borkowski, Rafal E.

    In situ reduction and oxidation of nickel from solid oxide fuel cells in a Titan ETEM A. Faes1. The in situ reduction and re-oxidation of the FIB prepared TEM lamellae is performed in a FEI Titan equipped

  10. Rules of Stereoselectivity in Tandem Oxidative Polycyclization Reaction with Rhenium(VII) Oxides

    E-print Network

    Keinan, Ehud

    Rules of Stereoselectivity in Tandem Oxidative Polycyclization Reaction with Rhenium(VII) Oxides, Israel ReceiVed April 17, 1998 The tandem oxidative polycyclization reaction with rhenium- (VII) reagents

  11. Oxidation of Octopus vulgaris hemocyanin by nitrogen oxides

    SciTech Connect

    Salvato, B.; Giacometti, G.M.; Beltramini, M.; Zilio, F.; Giacometti, G.; Magliozzo, R.S.; Peisach, J.

    1989-01-24

    The reaction of Octopus vulgaris hemocyanin with nitrite was studied under a variety of conditions in which the green half-met derivative is formed. Analytical evidence shows that the amount of chemically detectable nitrite in various samples of the derivative is not proportional to the cupric copper detected by EPR. The kinetics of oxidation of hemocyanin as a function of protein concentration and pH, in the presence of nitrite and ascorbate, is consistent with a scheme in which NO/sub 2/ is the reactive oxidant. We suggest that the green half-methemocyanin contains a metal center with one cuprous and one cupric copper without an exogenous nitrogen oxide ligand.

  12. Supercapacitors with graphene oxide separators and reduced graphite oxide electrodes

    NASA Astrophysics Data System (ADS)

    Shulga, Y. M.; Baskakov, S. A.; Baskakova, Y. V.; Volfkovich, Y. M.; Shulga, N. Y.; Skryleva, E. A.; Parkhomenko, Y. N.; Belay, K. G.; Gutsev, G. L.; Rychagov, A. Y.; Sosenkin, V. E.; Kovalev, I. D.

    2015-04-01

    A supercapacitor (SC) with electrodes fabricated from graphite oxide reduced by a microwave exfoliation (MEGO) method and the separator made from the graphite oxide paper (GOP) formed after precipitation of water suspension of graphene oxide was designed for the first time. The specific capacitance of this SC exceeded 200 F/g. The specific area of our MEGO is 2400 m2/g when measured using the standard contact porosimetry method, whereas it is several times smaller (?600 m2/g) when measured by using the Brunauer-Emmett-Teller method based on the low-temperature nitrogen adsorption. By using the angle resolved X-ray photoelectron spectroscopy we found that surface layers of the GOP separator contain smaller oxygen concentration than the bulk layers.

  13. Anomalous oxidation states in oxide multilayers for fuel cell applications

    SciTech Connect

    Perkins, James [Imperial College, London; Fearn, Sarah [Imperial College, London; Cook, S. N. [Imperial College, London; Srinivasan, R. [Imperial College, London; Rouleau, Christopher M [ORNL; Christen, Hans M [ORNL; West, G. D. [Imperial College, London; Morris, R. J. H. [Imperial College, London; Fraser, H. L. [Imperial College, London; Skinner, Stephen [Imperial College, London; Kilner, John [Imperial College, London; McComb, David [Imperial College, London

    2010-01-01

    Significant interest has been directed towards interface enhanced ionic conductivity. Advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) have been used to characterize CeO2/Ce0.85Sm0.15O2 multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and 18O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of this remarkable metastability of Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed.

  14. Highly oxidized graphene nanosheets via the oxidization of detonation carbon

    NASA Astrophysics Data System (ADS)

    Nepal, A.; Chiu, G.; Xie, J.; Singh, G. P.; Ploscariu, N.; Klankowski, S.; Sung, T.; Li, J.; Flanders, B. N.; Hohn, K. L.; Sorensen, C. M.

    2015-05-01

    A unique approach was developed to produce highly oxygenated graphene nanosheets (OGNs) by solution-based oxidation of the pristine graphene nanosheets (GNs) prepared via a controlled detonation of acetylene with oxygen. The produced OGNs are about 250 nm in size and are hydrophilic in nature. The C/O ratio was dramatically reduced from 49:1 in the pristine GNs to about 1:1 in OGNs, as determined by X-ray photoelectron spectroscopy. This C/O in OGNs is the least ever found in all oxidized graphitic materials that have been reported. Thus, the OGNs produced from the detonated GNs with such high degree of oxidation herein yield a novel and promising material for future applications.

  15. Growth of oxide laser crystals

    NASA Astrophysics Data System (ADS)

    Kokta, Milan

    2007-09-01

    Optically pumped solid state lasers are frequently single crystals of inorganic oxides containing active elements. While, most of these crystals are simple inorganic oxides or binary mixtures of two oxides by adding active ions and activators, sometimes in significant quantities, these system become more complex. Resulting mixtures of four sometimes five oxides display more complicated properties than are those of simple oxides. Examples of such systems are CTH:YAG (Chromium, Thulium, Holmium Garnet), and CTE:YAG (Chromium, Thulium, Erbium Garnet). The need for very high optical quality crystal in laser applications made the manufacture (crystal growth and fabrication) one of the most demanding manufacturing processes. A description of the growth of research and development type crystals, as well as scaling the process to industrial level is described. The best understood and most practiced technique in commercial crystal growth is described along with its advantages and limitations. The effects of composition and properties of individual crystals on process variables, growth parameters, and thermal designs are described. The crystal quality enhancement and control by recognizing, understanding, and minimizing or elimination of crystal defects are described. Emphasis is given to material properties that play a role in the selection of growth parameters for individual host systems such as garnet-based or corundum-based laser crystals.

  16. Nanoelectronics in oxides and semiconductors

    NASA Astrophysics Data System (ADS)

    Cheng, Guanglei

    The success of silicon industry lies on three major properties of silicon, an easily formed oxide layer to allow field effect operation, tunability of carrier density and high device scalability. All these features exist in oxides, together with some novel properties such as ferroelectricity, magnetic effects and metal-insulator transition. With the recent development in material growth method including molecular beam epitaxy (MBE), pulsed laser deposition (PLD) and reflection high energy electron diffraction (REED), atomically engineered oxide interfaces become available, thus opening the door to the novel oxide nanoelectronics. In this dissertation we create and study nanoelectronics in oxides, semiconductors and hybrid of these two. We used a conductive atomic force microscope tip to write single electron transistors in the 3-unit-cell-LaAlO 3/SrTiO3 heterostructure and observed ferroelectric tunneling behaviors. We also fabricated ferroelectric field transistors directly on silicon using strained SrTiO3 ferroelectric film and further confirmed the ferroelectric properties of this device. Meanwhile, we developed an ultrasensitive microwave capacitance sensor to study the electronic properties of self-assembled quantum dots and the switching mechanism of memristive devices. The integration of this sensor to a home made atomic force microscope provides an important tool to study the dielectric properties at nanoscale.

  17. Solid oxide electrochemical reactor science.

    SciTech Connect

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    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 oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  18. Tryptophan oxidation photosensitized by pterin.

    PubMed

    Thomas, Andrés H; Serrano, Mariana P; Rahal, Virginie; Vicendo, Patricia; Claparols, Catherine; Oliveros, Esther; Lorente, Carolina

    2013-10-01

    Pterins are normal components of cells and they have been previously identified as good photosensitizers under UV-A irradiation, inducing DNA damage and oxidation of nucleotides. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the oxidation of another class of biomolecules, amino acids, using tryptophan (Trp) as a model compound. Irradiation of Ptr in the UV-A spectral range (350 nm) in aerated aqueous solutions containing Trp led to the consumption of the latter, whereas the Ptr concentration remained unchanged. Concomitantly, hydrogen peroxide (H?O?) was produced. Although Ptr is a singlet oxygen ((1)O?) sensitizer, the degradation of Trp was inhibited in O?-saturated solutions, indicating that a (1)O?-mediated process (type II oxidation) was not an important pathway leading to Trp oxidation. By combining different analytical techniques, we could establish that a type I photooxidation was the prevailing mechanism, initiated by an electron transfer from the Trp molecule to the Ptr triplet excited state, yielding the corresponding radical ions (Trp(·+)/Trp(-H)· and Ptr(·-)). The Trp reaction products that could be identified by UPLC-mass spectrometry are in agreement with this conclusion. PMID:23747929

  19. Novel Interface-Mediated Metastable Oxide Phases: Vanadium Oxides on Pd(111)

    SciTech Connect

    Surnev, S.; Kresse, G.; Ramsey, M. G.; Netzer, F. P.

    2001-08-20

    In the growth process of ultrathin films of vanadium oxides on Pd(111), a sequence of novel oxide phases with layer-dependent structures and oscillating oxidation states has been detected experimentally and understood theoretically. These phases are interface mediated and metastable with respect to further oxide growth. Transformation into the stable oxide configuration occurs beyond a critical thickness, where energetics combined with kinetic limitations determine the oxide multilayer structure.

  20. Catalytic wet oxidations of aromatic compounds over supported copper oxides

    Microsoft Academic Search

    Ayumu Onda; Yotaro Suzuki; Shinji Takemasa; Koji Kajiyoshi; Kazumichi Yanagisawa

    2008-01-01

    Catalytic wet oxidations of naphthalene as a model compound of persistent aromatic compounds were carried out with hydrogen\\u000a peroxide in a closed autoclave lined with Teflon. CuO\\/Al2O3 and CuO\\/AC catalyst showed the high activity for the naphthalene oxidation with hydrogen peroxide of 1.0 mol L?1 at 100 °C. Naphthalene, whose initial concentration was 1.0 g L?1, was converted completely and the concentration of water-soluble organic

  1. Electrochemical reduction and oxidation of molybdenum oxides in propylene carbonate

    SciTech Connect

    Vereshchagina, I.S.; Tikhanov, K.I.; Makhalov, N.A.

    1982-02-10

    In the search for cathodes that can be used in reversibly functioning power sources with aprotic electrolytes, the molybdenum oxide electrode was revealed as promising. The high specific energy of power sources based on the Li-MoO/sub 3/ system and the cycling performance of the MoO/sub 3/ electrode have been pointed out. However, little is known concerning the processes taking place at the electrode and concerning the factors influencing reversibility of the electrodes. It was the aim of the present work to examine the electrochemical behavior of the molybdenum oxide electrode in 1 M LiClO/sub 4/ solution in propylene carbonate (PC) during cycling.

  2. Method for hot pressing beryllium oxide articles

    DOEpatents

    Ballard, Ambrose H. (Oak Ridge, TN); Godfrey, Jr., Thomas G. (Oak Ridge, TN); Mowery, Erb H. (Clinton, TN)

    1988-01-01

    The hot pressing of beryllium oxide powder into high density compacts with little or no density gradients is achieved by employing a homogeneous blend of beryllium oxide powder with a lithium oxide sintering agent. The lithium oxide sintering agent is uniformly dispersed throughout the beryllium oxide powder by mixing lithium hydroxide in an aqueous solution with beryllium oxide powder. The lithium hydroxide is converted in situ to lithium carbonate by contacting or flooding the beryllium oxide-lithium hydroxide blend with a stream of carbon dioxide. The lithium carbonate is converted to lithium oxide while remaining fixed to the beryllium oxide particles during the hot pressing step to assure uniform density throughout the compact.

  3. Catalyst for Oxidation of Volatile Organic Compounds

    NASA Technical Reports Server (NTRS)

    Wood, George M. (Inventor); Upchurch, Billy T. (Inventor); Schryer, David R. (Inventor); Davis, Patricia P. (Inventor); Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); Schyryer, Jacqueline L. (Inventor); DAmbrosia, Christine M. (Inventor)

    2000-01-01

    Disclosed is a process for oxidizing volatile organic compounds to carbon dioxide and water with the minimal addition of energy. A mixture of the volatile organic compound and an oxidizing agent (e.g. ambient air containing the volatile organic compound) 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.

  4. Graphite Oxidation Thermodynamics/Reactions

    SciTech Connect

    Propp, W.A.

    1998-09-01

    The vulnerability of graphite-matrix spent nuclear fuel to oxidation by the ambient atmosphere if the fuel canister is breached was evaluated. Thermochemical and kinetic data over the anticipated range of storage temperatures (200 to 400 C) were used to calculate the times required for a total carbon mass loss of 1 mgcm-2 from a fuel specimen. At 200 C, the time required to produce even this small loss is large, 900,000 yr. However, at 400 C the time required is only 1.9 yr. The rate of oxidation at 200 C is negligible, and the rate even at 400 C is so small as to be of no practical consequence. Therefore, oxidation of the spent nuclear fuel upon a loss of canister integrity is not anticipated to be a concern based upon the results of this study.

  5. Aromatic-radical oxidation kinetics

    SciTech Connect

    Not Available

    1992-01-01

    Research progress in three areas is described. Progress achieved in the extensive experimental investigation of the oxidation and pyrolysis of cyclopentadiene is summarized first. The mechanistic implications of the experimental work are also discussed. An overview is given of the successful research effort devoted to modelling flow reactor toluene and benzene oxidation data. As mentioned above, one of the ultimate goals of this research is to develop a comprehensive, detailed chemical kinetic model of aromatics oxidation. The success already achieved in this effort augurs well for reaching the broader goal. The toluene/benzene model, however, does have a number of shortcomings which suggest the need for further experiments. A description is given of attempts to predict the laminar flame speeds of toluene and benzene. The difficulties encountered and the solutions found highlight the need of an examination of certain chemical steps that impact most the energy release of a burning aromatic fuel.

  6. Electrochemical oxidation of chemical weapons

    SciTech Connect

    Surma, J.E.

    1994-05-01

    Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced Concepts Program. The tests examined the effectiveness of CEO in destroying sarin (GB), a chemical nerve agent. The tests used 0.5 mL, 0.95 mL, and 1.0 mL of GB, corresponding to 544 mg, 816 mg, and 1,090 mg, respectively, of GB. Analysis of the off gas showed that, under continuous processing of the GB agent, destruction efficiencies of better than six 9s (99.9999% destroyed) could be achieved.

  7. Catalytic oxidation of secondary alcohols

    SciTech Connect

    Augustine, R.L.; Doyle, L.K.

    1992-11-01

    The dioxygen oxidation of alcohols over platinum catalysts has been known for a long time. While of potential importance in synthetic procedures, this process has never found extensive use except in carbohydrate oxidations. Some reasons for this is the fact that this reaction only appears to work well in an aqueous medium in the presence of rather large amounts of a Pt black catalyst. Results obtained here show that supported Pt catalysts can be used to promote this oxidation in organic solvents provided a small amount of water is added to the reaction medium. It was also estabilished that the reaction takes place on the more coordinately unsaturated corner atoms on the Pt surface.

  8. Catalytic oxidation of secondary alcohols

    SciTech Connect

    Augustine, R.L.; Doyle, L.K.

    1992-01-01

    The dioxygen oxidation of alcohols over platinum catalysts has been known for a long time. While of potential importance in synthetic procedures, this process has never found extensive use except in carbohydrate oxidations. Some reasons for this is the fact that this reaction only appears to work well in an aqueous medium in the presence of rather large amounts of a Pt black catalyst. Results obtained here show that supported Pt catalysts can be used to promote this oxidation in organic solvents provided a small amount of water is added to the reaction medium. It was also estabilished that the reaction takes place on the more coordinately unsaturated corner atoms on the Pt surface.

  9. [Solidification of volatile oil with graphene oxide].

    PubMed

    Yan, Hong-Mei; Jia, Xiao-Bin; Zhang, Zhen-Hai; Sun, E; Xu, Yi-Hao

    2015-02-01

    To evaluate the properties of solidifying volatile oil with graphene oxide, clove oil and zedoary turmeric oil were solidified by graphene oxide. The amount of graphene oxide was optimized with the eugenol yield and curcumol yield as criteria. Curing powder was characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The effects of graphene oxide on dissolution in vitro and thermal stability of active components were studied. The optimum solidification ratio of graphene oxide to volatile oil was 1:1. Dissolution rate of active components had rare influence while their thermal stability improved after volatile oil was solidified. Solidifying herbal volatile oil with graphene oxide deserves further study. PMID:25975033

  10. Oxidation of Zircaloy by steam

    NASA Astrophysics Data System (ADS)

    Moalem, M.; Olander, D. R.

    1991-06-01

    The oxidation of Zircaloy by steam and by steam-hydrogen mixtures was studied experimentally from 1100-1600°C using the continuously-recording gravimetric method. Parabolic kinetics based on oxygen diffusion in the solid were followed at low temperatures but steam starvation, nonisothermal behavior, and finite medium effects dominated at temperatures above about 1500°C. The effect of high dilution of the steam by hydrogen was to accelerate oxidation initially because of the heat released by hydrogen absorption in the metal. At high temperatures, oxygen uptake kinetics were nonparabolic and required analysis by a fundamental diffusion model in which the initial effects are incorporated.

  11. Phase transformation in the oxides

    Microsoft Academic Search

    Franklin F. Y. Wang; Kedar P. Gupta

    1973-01-01

    This paper reviews phase transformations in the oxides, and briefly examines the similarities and dissimilarities with the\\u000a phase transitions in metals. A few topics selected for the discussion, include, displacive phase transitions, order-disorder\\u000a transitions, and clustering and precipitation. The displacive transition involves the oxygen polyhedra, and is usually found\\u000a in ferroelectric and antiferroelectric oxides, such as, BaTiO3, SrTiO3, PbZrO3, and

  12. Sulfides and oxides in comets

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1988-01-01

    Metal abundances associated with Sun-grazing P/comet Ikeya-Seki 1965f, the mineralogy of chrondritic interplanetary dust particles and cosmochemical affinities of Co, V, Cr, and Ni in extraterrestrial materials and probable vaporization data for nonsilicate minerals are used to evaluate the putative dearth of nonsilicates in short-period comets. It is concluded that sulfides and oxides are common, albeit minor, constituents of these comets. Sulfides and oxides can form in situ during perihelion passage in the nucleus of active short-period comets by sulfidation of Mg, Fe-silicates.

  13. Solid oxide fuel cell generator

    DOEpatents

    Draper, R.; George, R.A.; Shockling, L.A.

    1993-04-06

    A solid oxide fuel cell generator has a pair of spaced apart tubesheets in a housing. At least two intermediate barrier walls are between the tubesheets and define a generator chamber between two intermediate buffer chambers. An array of fuel cells have tubes with open ends engaging the tubesheets. Tubular, axially elongated electrochemical cells are supported on the tubes in the generator chamber. Fuel gas and oxidant gas are preheated in the intermediate chambers by the gases flowing on the other side of the tubes. Gas leakage around the tubes through the tubesheets is permitted. The buffer chambers reentrain the leaked fuel gas for reintroduction to the generator chamber.

  14. Solid oxide fuel cell generator

    DOEpatents

    Draper, Robert (Churchill Boro, PA); George, Raymond A. (Pittsburgh, PA); Shockling, Larry A. (Plum Borough, PA)

    1993-01-01

    A solid oxide fuel cell generator has a pair of spaced apart tubesheets in a housing. At least two intermediate barrier walls are between the tubesheets and define a generator chamber between two intermediate buffer chambers. An array of fuel cells have tubes with open ends engaging the tubesheets. Tubular, axially elongated electrochemical cells are supported on the tubes in the generator chamber. Fuel gas and oxidant gas are preheated in the intermediate chambers by the gases flowing on the other side of the tubes. Gas leakage around the tubes through the tubesheets is permitted. The buffer chambers reentrain the leaked fuel gas for reintroduction to the generator chamber.

  15. Ultrafast graphene oxide humidity sensors.

    PubMed

    Borini, Stefano; White, Richard; Wei, Di; Astley, Michael; Haque, Samiul; Spigone, Elisabetta; Harris, Nadine; Kivioja, Jani; Ryhänen, Tapani

    2013-12-23

    Sensors allow an electronic device to become a gateway between the digital and physical worlds, and sensor materials with unprecedented performance can create new applications and new avenues for user interaction. Graphene oxide can be exploited in humidity and temperature sensors with a number of convenient features such as flexibility, transparency and suitability for large-scale manufacturing. Here we show that the two-dimensional nature of graphene oxide and its superpermeability to water combine to enable humidity sensors with unprecedented response speed (?30 ms response and recovery times). This opens the door to various applications, such as touchless user interfaces, which we demonstrate with a 'whistling' recognition analysis. PMID:24206232

  16. Oxidation of DOPAC by nitric oxide: effect of superoxide dismutase.

    PubMed

    Laranjinha, João; Cadenas, Enrique

    2002-05-01

    This study aimed to characterize the redox interaction between 3,4-dihydroxyphenylacetic acid (DOPAC) and nitric oxide (.NO), and to assess the reductive and oxidative decay pathways of the DOPAC semiquinone originating from this interaction. The reaction between DOPAC and.NO led to the formation of the DOPAC semiquinone radical, detected by electron paramagnetic resonance (EPR) and stabilized by Mg(2+), and the nitrosyl anion detected as nitrosylmyoglobin. The EPR signal corresponding to the DOPAC semiquinone was modulated as follows: (i) it was suppressed by glutathione and ascorbic acid with the formation of new EPR spectra corresponding to the glutathionyl and ascorbyl radical, respectively; (ii) it was enhanced by Cu,Zn-superoxide dismutase; the enzyme also accelerated the decay of the semiquinone species to DOPAC quinone. These results are interpreted as a one-electron oxidation of DOPAC by.NO; the reductive decay of the semiquinone back to DOPAC was facilitated by reducing agents, such as glutathione and ascorbate, whereas the oxidative decay to DOPAC quinone was facilitated by superoxide dismutase. The latter effect is understood in terms of a reversible conversion of nitrosyl anion to.NO by the enzyme. The biological relevance of these reactions is also discussed in terms of the reactivity of peroxynitrite towards DOPAC as a model with implications for aerobic conditions. PMID:12065648

  17. Ligands and oxidants in ferrihemochrome formation and oxidative hemolysis*

    PubMed Central

    Itano, Harvey A.; Hirota, Kazuhiro; Vedvick, Thomas S.

    1977-01-01

    We have investigated the effect of size of a single neutral ring substituent on the induction of hemolytic anemia and the formation of a ferrihemochrome by substituted phenylhydrazines. The severity of induced anemia decreased with increase in size of a halogen atom or an alkyl group ortho to the hydrazino group, little anemia resulting from 2-iodophenylhydrazine and no anemia from 2-tert-butylphenylhydrazine. The size of a halogen atom or an alkyl group at the meta or para position had relatively little effect on the severity of induced anemia. The ability of an arylhydrazine to induce hemolytic anemia paralleled its ability to produce a ferrihemochrome with an exogenous ligand, probably the corresponding aryldiazene. In general, rapid and complete formation of ferrihemochrome occurred with arylhydrazines that induced severe anemia. The degree of hemolysis induced by an arylhydrazine was not related to its rate of autooxidation, i.e., the rate at which oxidants are formed by the reduction of oxygen. We propose a mechanism of arylhydrazine-induced oxidative denaturation based on the simultaneous formation of hydroxyl radical and aryldiazene ferrihemochrome in a reaction of oxyhemoglobin with arylhydrazine. We suggest that after oxidation of the porphyrin ring is initiated by a hydroxyl radical, oxidative cleavage of the ring is facilitated by the presence of a large ligand in the heme crevice. Thus, aryldiazene ferrihemochrome may contribute to instability in a hemoglobin molecule, whereas globin ferrihemochrome results from instability. PMID:267949

  18. Mechanistic Aspects of Pyrite Oxidation in an Oxidizing Gaseous

    E-print Network

    Sparks, Donald L.

    -. Isotopic labeling experiments showed that after this exposure sequence the oxygen in the sulfate product vapor, both SO4 2- and iron oxyhydroxide became significant products. Isotopic labeling experiments some of the microscopic details of pyrite oxidation is through isotopic labeling experiments

  19. Selective oxidation of benzene to phenol over FeAlPO catalysts using nitrous oxide as oxidant.

    PubMed

    Shiju, N Raveendran; Fiddy, Steven; Sonntag, Olivier; Stockenhuber, Michael; Sankar, Gopinathan

    2006-12-21

    A tetrahedrally coordinated iron in framework substituted microporous AlPO-5 catalysts are shown to be active and selective for the hydroxylation of benzene to phenol, using nitrous oxide as the oxidant. PMID:17136259

  20. Oxone\\/Co 2+ oxidation as an advanced oxidation process: Comparison with traditional Fenton oxidation for treatment of landfill leachate

    Microsoft Academic Search

    Jianhui Sun; Xiaoyan Li; Jinglan Feng; Xiaoke Tian

    2009-01-01

    In this paper, the application of Fenton and Oxone\\/Co2+ oxidation processes for landfill leachate treatment was investigated. The removal of the chemical oxygen demand (COD), suspended substances (SS) and the color of the landfill leachate by Fenton oxidation to that by Oxone\\/Co2+ oxidation were compared under optimal operational conditions. For Fenton oxidation process, the optimal conditions were determined as: [H2O2]=80mmol