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Sample records for heat-activated persulfate oxidation

  1. 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.

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

    PubMed

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

    2015-12-30

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

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

    NASA Astrophysics Data System (ADS)

    Quig, L.; Johnson, G. R.

    2015-12-01

    characterizing the overall transport behavior and application of persulfate/heat-activated persulfate in a natural porous media for the ISCO of residual nonaqueous phase liquid, this work aids in improving the implementation of persulfate ISCO systems.

  4. Heat-activated persulfate oxidation of PFOA, 6:2 fluorotelomer sulfonate, and PFOS under conditions suitable for in-situ groundwater remediation.

    PubMed

    Park, Saerom; Lee, Linda S; Medina, Victor F; Zull, Aaron; Waisner, Scott

    2016-02-01

    PFOA (perfluorooctanoic acid) oxidation (0.121-6.04 μM) by heat-activated persulfate was evaluated at 20-60 °C with 4.2-84 mM [Formula: see text] and in the presence of soluble fuel components to assess feasibility for in-situ remediation of groundwater. 6:2 fluorotelomer sulfonic acid/sulfonate (6:2 FTSA) and PFOS (perfluorooctanesulfonic acid) persulfate oxidation was also evaluated in a subset of conditions given their co-occurrence at many sites. High performance liquid chromatography electron spray tandem mass spectrometry was used for organic analysis and fluoride was measured using a fluoride-specific electrode. PFOA pseudo-1st order transformation rates (k1,PFOA) increased with increasing temperature (half-lives from 0.1 to 7 d for 60 to 30 °C) sequentially removing CF2 groups ('unzipping') to shorter chain perfluoroalkyl carboxylic acids (PFCAs) and F(-). At 50 °C, a 5-fold increase in [Formula: see text] led to a 5-fold increase in k1,PFOA after which self-scavenging by sulfate radicals decreased the relative rate of increase with more [Formula: see text] . Benzene, toluene, ethylbenzene and xylene did not affect k1,PFOA even at 40 times higher molar concentrations than PFOA. A modeling approach to explore pathways strongly supported that for 6:2 FTSA, both the ethyl linkage and CF2-CH2 bond of 6:2 FTSA oxidize simultaneously, resulting in a ratio of ∼25/75 PFHpA/PFHxA. The effectiveness of heat-activated [Formula: see text] on PFOA oxidation was reduced in a soil slurry; therefore, repeated persulfate injections are required to efficiently achieve complete oxidation in the field. However, PFOS remained unaltered even at higher activation temperatures, thus limiting the sole use of heat-activated persulfate for perfluoroalkyl substances removal in the field. PMID:26692515

  5. Heat-activated persulfate oxidation of PFOA, 6:2 fluorotelomer sulfonate, and PFOS under conditions suitable for in-situ groundwater remediation.

    PubMed

    Park, Saerom; Lee, Linda S; Medina, Victor F; Zull, Aaron; Waisner, Scott

    2016-02-01

    PFOA (perfluorooctanoic acid) oxidation (0.121-6.04 μM) by heat-activated persulfate was evaluated at 20-60 °C with 4.2-84 mM [Formula: see text] and in the presence of soluble fuel components to assess feasibility for in-situ remediation of groundwater. 6:2 fluorotelomer sulfonic acid/sulfonate (6:2 FTSA) and PFOS (perfluorooctanesulfonic acid) persulfate oxidation was also evaluated in a subset of conditions given their co-occurrence at many sites. High performance liquid chromatography electron spray tandem mass spectrometry was used for organic analysis and fluoride was measured using a fluoride-specific electrode. PFOA pseudo-1st order transformation rates (k1,PFOA) increased with increasing temperature (half-lives from 0.1 to 7 d for 60 to 30 °C) sequentially removing CF2 groups ('unzipping') to shorter chain perfluoroalkyl carboxylic acids (PFCAs) and F(-). At 50 °C, a 5-fold increase in [Formula: see text] led to a 5-fold increase in k1,PFOA after which self-scavenging by sulfate radicals decreased the relative rate of increase with more [Formula: see text] . Benzene, toluene, ethylbenzene and xylene did not affect k1,PFOA even at 40 times higher molar concentrations than PFOA. A modeling approach to explore pathways strongly supported that for 6:2 FTSA, both the ethyl linkage and CF2-CH2 bond of 6:2 FTSA oxidize simultaneously, resulting in a ratio of ∼25/75 PFHpA/PFHxA. The effectiveness of heat-activated [Formula: see text] on PFOA oxidation was reduced in a soil slurry; therefore, repeated persulfate injections are required to efficiently achieve complete oxidation in the field. However, PFOS remained unaltered even at higher activation temperatures, thus limiting the sole use of heat-activated persulfate for perfluoroalkyl substances removal in the field.

  6. 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.

  7. 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.

  8. Degradation of toluene, ethylbenzene, and xylene using heat and chelated-ferrous iron activated persulfate oxidation

    NASA Astrophysics Data System (ADS)

    Mondal, P.; Sleep, B.

    2014-12-01

    Toluene, ethylbenze, and xylene (TEX) are common contaminants in the subsurface. Activated persulfate has shown promise for degrading a wide variety of organic compounds. However, studies of persulfate application for in situ degradation of TEX and effects on the subsequent bioremediation are limited. In this work, degradation studies of TEX in aqueous media and soil are being conducted using heat activated and chelated-ferrous iron activated persulfate oxidation in batch and flow-through column experiments. In the batch experiments, sodium persulfate is being used at different concentrations to provide an initial persulfate to TEX molar ratios between 10:1 and 100:1. Sodium persulfate solutions are being activated at 20, 37, 60, and 80 oC temperatures for the heat activated oxidation. For the chelated-ferrous iron activated oxidation, ferrous iron and citric acid, both are being used at concentration of 5 mM. In the experiments with soil slurry, a soil to water ratio of 1 to 5 is being used. Flow through water saturated column experiments are being conducted with glass columns (45 cm in length and 4 cm in diameter) uniformly packed with soils, and equilibrated with water containing TEX at the target concentrations. Both the heat activation and chelated-ferrous iron activation of persulfate are being employed in the column experiments. Future experiments are planned to determine the suitability of persulfate oxidation of TEX on the subsequent biodegradation using batch microcosms containing TEX degrading microbial cultures. In these experiments, the microbial biomass will be monitored using total phospholipids, and the microbial community will be determined using quantitative real-time polymerase chain reaction (qPCR) on the extracted DNA. This study is expected to provide suitable operating conditions for in situ chemical oxidation of TEX with activated persulfate followed by bioremediation.

  9. Water temperature significantly impacts the formation of iodinated haloacetamides during persulfate oxidation.

    PubMed

    Chu, Wenhai; Hu, Jianglin; Bond, Tom; Gao, Naiyun; Xu, Bin; Yin, Daqiang

    2016-07-01

    The use of persulfate oxidation processes is receiving increasing interest for the removal of aquatic contaminants. However, it is unknown whether its application in the presence of iodide has the potential to directly form iodinated DBPs. This study investigated formation of six chlorinated, brominated and iodinated di-haloacetamides (DHAcAms) during persulfate oxidation in the presence of bromide and iodide. Formation of the same DHAcAms during chlorination was monitored for comparison. Persulfate oxidation of natural water formed diiodoacetamide (DIAcAm), and heat-activated persulfate, at 45 °C and 55 °C, generated bromoiodoacetamide (BIAcAm) and dibromoacetamide (DBAcAm), besides DIAcAm. At an ambient iodide concentration of 0.3 μM, total DHAcAms increased slightly from 0.43 to 0.57 nM as the water temperature increased from 4 °C to 35 °C, respectively (only DIAcAm detected), then significantly increased to 1.6 nM at 55 °C (DIAcAm, BIAcAm and DBAcAm detected). Equivalent total DHAcAm concentrations in the presence of 3.0 μM iodide were 0.5, 0.91 and 2.1 nM, respectively. Total DHAcAms formed during chlorination, predominantly dichloroacetamide (DCAcAm) and bromochloroacetamide (BCAcAm), were always significantly higher than that during persulfate oxidation. However, an integrated risk assessment showed the toxicity resulting from the DHAcAms was higher during persulfate oxidation than chlorination. An increase in water temperature from 25 °C to 55 °C significantly increased the integrated toxic risk values for both persulfate oxidation and chlorination. Use of persulfate oxidation should be weighed against the formation of high-toxicity iodinated HAcAms in waters with high ambient iodide concentrations.

  10. 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.

  11. Lipid extraction from microalgae cell using persulfate-based oxidation.

    PubMed

    Seo, Yeong Hwan; Sung, Mina; Oh, You-Kwan; Han, Jong-In

    2016-01-01

    In this study, persulfate, a solid-type oxidant, was adopted as a substitute for hydrogen peroxide in extracting lipid from microalgae biomass. Microalgae cells were concentrated at pH 3 and with 200mg/L of ferric chloride, conditions which can activate oxidants such as hydrogen peroxide and persulfate. At a persulfate concentration of 2mM and a reaction temperature of 90°C, exceedingly high extraction efficiency over 95% was obtained, which was higher than with 0.5% hydrogen peroxide at the same temperature. This result showed that persulfate is sufficiently powerful and incomparably cheap enough to replace the potent yet expensive oxidant. It appears that combining iron-based coagulation and persulfate-based lipid extraction is indeed a competitive approach that can possibly lighten the process burden for the microalgae-derived biodiesel production. PMID:26614226

  12. Homogeneous and Heterogeneous Photocatalytic Water Oxidation by Persulfate.

    PubMed

    Fukuzumi, Shunichi; Jung, Jieun; Yamada, Yusuke; Kojima, Takahiko; Nam, Wonwoo

    2016-04-20

    Photocatalytic water oxidation by persulfate (Na2 S2 O8 ) with [Ru(bpy)3 ](2+) (bpy=2,2'-bipyridine) as a photocatalyst provides a standard protocol to study the catalytic reactivity of water oxidation catalysts. The yield of evolved oxygen per persulfate is regarded as a good index for the catalytic reactivity because the oxidation of bpy of [Ru(bpy)3 ](2+) and organic ligands of catalysts competes with the catalytic water oxidation. A variety of metal complexes act as catalysts in the photocatalytic water oxidation by persulfate with [Ru(bpy)3 ](2+) as a photocatalyst. Herein, the catalytic mechanisms are discussed for homogeneous water oxidation catalysis. Some metal complexes are converted to metal oxide or hydroxide nanoparticles during the photocatalytic water oxidation by persulfate, acting as precursors for the actual catalysts. The catalytic reactivity of various metal oxides is compared based on the yield of evolved oxygen and turnover frequency. A heteropolynuclear cyanide complex is the best catalyst reported so far for the photocatalytic water oxidation by persulfate and [Ru(bpy)3 ](2+) , affording 100 % yield of O2 per persulfate.

  13. Persulfate activation during exertion of total oxidant demand.

    PubMed

    Teel, Amy L; Elloy, Farah C; Watts, Richard J

    2016-09-01

    Total oxidant demand (TOD) is a parameter that is often measured during in situ chemical oxidation (ISCO) treatability studies. The importance of TOD is based on the concept that the oxidant demand created by soil organic matter and other reduced species must be overcome before contaminant oxidation can proceed. TOD testing was originally designed for permanganate ISCO, but has also recently been applied to activated persulfate ISCO. Recent studies have documented that phenoxides activate persulfate; because soil organic matter is rich in phenolic moieties, it may activate persulfate rather than simply exerting TOD. Therefore, the generation of reactive oxygen species was investigated in three soil horizons of varied soil organic carbon content over 5-day TOD testing. Hydroxyl radical may have been generated during TOD exertion, but was likely scavenged by soil organic matter. A high flux of reductants + nucleophiles (e.g. alkyl radicals + superoxide) was generated as TOD was exerted, resulting in the rapid destruction of the probe compound hexachloroethane and the common groundwater contaminant trichloroethylene (TCE). The results of this research document that, unlike permanganate TOD, contaminant destruction does occur as TOD is exerted in persulfate ISCO systems and is promoted by the activation of persulfate by soil organic matter. Future treatability studies for persulfate ISCO should consider contaminant destruction as TOD is exerted, and the potential for persulfate activation by soil organic matter. PMID:27269993

  14. Water temperature significantly impacts the formation of iodinated haloacetamides during persulfate oxidation.

    PubMed

    Chu, Wenhai; Hu, Jianglin; Bond, Tom; Gao, Naiyun; Xu, Bin; Yin, Daqiang

    2016-07-01

    The use of persulfate oxidation processes is receiving increasing interest for the removal of aquatic contaminants. However, it is unknown whether its application in the presence of iodide has the potential to directly form iodinated DBPs. This study investigated formation of six chlorinated, brominated and iodinated di-haloacetamides (DHAcAms) during persulfate oxidation in the presence of bromide and iodide. Formation of the same DHAcAms during chlorination was monitored for comparison. Persulfate oxidation of natural water formed diiodoacetamide (DIAcAm), and heat-activated persulfate, at 45 °C and 55 °C, generated bromoiodoacetamide (BIAcAm) and dibromoacetamide (DBAcAm), besides DIAcAm. At an ambient iodide concentration of 0.3 μM, total DHAcAms increased slightly from 0.43 to 0.57 nM as the water temperature increased from 4 °C to 35 °C, respectively (only DIAcAm detected), then significantly increased to 1.6 nM at 55 °C (DIAcAm, BIAcAm and DBAcAm detected). Equivalent total DHAcAm concentrations in the presence of 3.0 μM iodide were 0.5, 0.91 and 2.1 nM, respectively. Total DHAcAms formed during chlorination, predominantly dichloroacetamide (DCAcAm) and bromochloroacetamide (BCAcAm), were always significantly higher than that during persulfate oxidation. However, an integrated risk assessment showed the toxicity resulting from the DHAcAms was higher during persulfate oxidation than chlorination. An increase in water temperature from 25 °C to 55 °C significantly increased the integrated toxic risk values for both persulfate oxidation and chlorination. Use of persulfate oxidation should be weighed against the formation of high-toxicity iodinated HAcAms in waters with high ambient iodide concentrations. PMID:27076062

  15. 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

  16. 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)).

  17. 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.

  18. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability. PMID:27450342

  19. Ultrasound assisted, thermally activated persulfate oxidation of coal tar DNAPLs.

    PubMed

    Peng, Libin; Wang, Li; Hu, Xingting; Wu, Peihui; Wang, Xueqing; Huang, Chumei; Wang, Xiangyang; Deng, Dayi

    2016-11-15

    The feasibility of ultrasound assisted, thermally activated persulfate for effective oxidation of twenty 2-6 ringed coal tar PAHs in a biphasic tar/water system and a triphasic tar/soil/water system were investigated and established. The results indicate that ultrasonic assistance, persulfate and elevated reaction temperature are all required to achieve effective oxidation of coal tar PAHs, while the heating needed can be provided by ultrasonic induced heating as well. Further kinetic analysis reveals that the oxidation of individual PAH in the biphasic tar/water system follows the first-order kinetics, and individual PAH oxidation rate is primary determined by the mass transfer coefficients, tar/water interfacial areas, the aqueous solubility of individual PAH and its concentration in coal tar. Based on the kinetic analysis and experimental results, the contributions of ultrasound, persulfate and elevated reaction temperature to PAHs oxidation were characterized, and the effects of ultrasonic intensity and oxidant dosage on PAHs oxidation efficiency were investigated. In addition, the results indicate that individual PAH degradability is closely related to its reactivity as well, and the high reactivity of 4-6 ringed PAHs substantially improves their degradability.

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

    PubMed

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

    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 degrees =2.6 V). The column study presented here simulates persulfate oxidation of TCE in porous media (glass beads and a sandy soil). Initial experiments were conducted to investigate persulfate transport in the absence of TCE in the column. The persulfate flushing exhibited a longer residence time and revealed a moderate persulfate interaction with soils. In TCE treatment experiments, the results indicate that the water or persulfate solution would push dissolved TCE from the column. Therefore, the effluent TCE concentration gradually increased to a maximum when about one pore volume was replaced with the flushing solution in the column. The presence of Fe2+ concentration within the column caused a quick drop in effluent TCE concentration and more TCE degradation was observed. When a TCE solution was flushing through the soil column, breakthrough of TCE concentration in the effluent was relatively slow. In contrast, when the soil column was flushed with a mixed solution of persulfate and TCE, persulfate appeared to preferentially oxidize soil oxidizable matter rather than TCE during transport. Hence, persulfate oxidation of soil organics may possibly reduce the interaction between TCE and soil (e.g., adsorption) and facilitate the transport of TCE through soil columns resulting in faster breakthrough.

  1. In situ remediation of ortho-nitrochlorobenzene in soil by dual oxidants (hydrogen peroxide/persulfate).

    PubMed

    Liu, Zhonghua; Guo, Weilin; Han, Xuemei; Li, Xianghui; Zhang, Ke; Qiao, Zhuangming

    2016-10-01

    The efficacies of catalyzed H2O2, activated persulfate, and catalyzed H2O2-persulfate processes for the degradation of ortho-nitrochlorobenzene (o-NCB) in soil were investigated. The application of catalyzed H2O2-persulfate process was promising, and after a careful adjustment of oxidants and activator doses, it demonstrated a considerable improvement in o-NCB degradation compared with activated persulfate process and catalyzed H2O2 process. The degradation of o-NCB in catalyzed H2O2-persulfate process was obviously influenced by the concentration of persulfate and H2O2, the molar ratio between persulfate and H2O2, the concentration of o-NCB, and initial pH. Degradation of o-NCB was obviously inhibited by the addition of tert-butyl alcohol, methanol, and phenol, suggesting that nitrobenzene was dominantly oxidized by HO· and SO4 (-)· generated in the catalyzed H2O2-persulfate process. The results from these studies demonstrated that the natural iron species present in soil could effectively facilitate the degradation of organic pollutants in the presence of H2O2 and persulfate. PMID:27406223

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

    EPA Science Inventory

    The extent of PAH transformation, the formation and transformation of reaction byproducts during persulfate oxidation of polycyclic aromatic hydrocarbons (PAHs) in coking plant soil was investigated. Pre-oxidation analyses indicated that oxygen-containing PAHs (oxy-PAHs) existed ...

  3. 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

  4. 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.

  5. 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

  6. Green mechanochemical oxidative decomposition of powdery decabromodiphenyl ether with persulfate.

    PubMed

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

    2016-01-25

    A method was developed for efficiently degrading powdery decabromodiphenyl ether (BDE209) by using mechanochemical (MC) activation of persulfate (PS). Characteristic Raman spectra of BDE209 corresponding to CBr and CO bonds were decreased in intensity and finally disappeared as the MC reaction proceeded. The BDE209 removal was influenced by the molar ratio of PS to BDE209, the mass ratio of milling ball to reaction mixtures, the ball size, and the ball rotation speed. Under optimal conditions, the new method could achieve a complete degradation, debromination and mineralization of BDE209 within 3h of milling. However, the degradation removal (or debromination efficiency) was decreased to only 51.7% (15.6%) and 67.8% (31.5%) for the use of CaO and peroxymonosulfate, respectively. The analyses of products demonstrated that once the degradation was initiated, BDE209 molecules were deeply debrominated and fully mineralized in the MC-PS system. The strong oxidizing ability of this system was due to the reactive sulfate radicals generated from the MC-enhanced activation of PS, which was confirmed with electron spin resonance spectroscopy. Because no toxic low brominated polybrominated diphenyl ethers were accumulated as byproducts, the proposed MC oxidative degradation method will have promising applications in the treatment of solid BDE209 at high concentrations. PMID:26474378

  7. Green mechanochemical oxidative decomposition of powdery decabromodiphenyl ether with persulfate.

    PubMed

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

    2016-01-25

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

  8. 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.

  9. Reduction and persulfate oxidation of nitro explosives in contaminated soils using Fe-bearing materials.

    PubMed

    Oh, Seok-Young; Yoon, Hyun-Su; Jeong, Tae-Yong; Kim, Sang Don; Kim, Dong-Wook

    2016-07-13

    The oxidative and reductive transformation of nitro explosives in contaminated soils with Fe-bearing materials and persulfate (S2O8(2-)) was examined via batch experiments. Zero-valent cast iron [Fe(0)], steel dust from a steel manufacturing plant, and FeS rapidly reduced 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soil under anaerobic conditions as long as a sufficient amount of water was present. The Fe-bearing materials also effectively activated persulfate to enhance the oxidative transformation of TNT and RDX in soil-water systems. Kinetically, reductive and oxidative transformations removed more than 90% of the explosives from a soil-water system within 5 h under the given conditions. Pseudo-first-order rates in the range of 0.7-23.4 h(-1) were observed. By increasing the concentration of persulfate or Fe-bearing materials, the oxidative transformation could be promoted. Treated soils via redox reactions using the Fe-bearing materials did not show significant toxicity, except for the case of TNT-contaminated soils oxidized by FeS-assisted persulfate. Considering the kinetics of explosive degradation and the toxicity of treated wastewaters and soils, Fe(0) or steel dust-assisted persulfate oxidation may be a safe option as an ex situ remediation process for the treatment of explosive-contaminated soils.

  10. Reduction and persulfate oxidation of nitro explosives in contaminated soils using Fe-bearing materials.

    PubMed

    Oh, Seok-Young; Yoon, Hyun-Su; Jeong, Tae-Yong; Kim, Sang Don; Kim, Dong-Wook

    2016-07-13

    The oxidative and reductive transformation of nitro explosives in contaminated soils with Fe-bearing materials and persulfate (S2O8(2-)) was examined via batch experiments. Zero-valent cast iron [Fe(0)], steel dust from a steel manufacturing plant, and FeS rapidly reduced 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in soil under anaerobic conditions as long as a sufficient amount of water was present. The Fe-bearing materials also effectively activated persulfate to enhance the oxidative transformation of TNT and RDX in soil-water systems. Kinetically, reductive and oxidative transformations removed more than 90% of the explosives from a soil-water system within 5 h under the given conditions. Pseudo-first-order rates in the range of 0.7-23.4 h(-1) were observed. By increasing the concentration of persulfate or Fe-bearing materials, the oxidative transformation could be promoted. Treated soils via redox reactions using the Fe-bearing materials did not show significant toxicity, except for the case of TNT-contaminated soils oxidized by FeS-assisted persulfate. Considering the kinetics of explosive degradation and the toxicity of treated wastewaters and soils, Fe(0) or steel dust-assisted persulfate oxidation may be a safe option as an ex situ remediation process for the treatment of explosive-contaminated soils. PMID:27327861

  11. Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions

    PubMed Central

    Yin, Penghua; Hu, Zhihao; Song, Xin; Liu, Jianguo; Lin, Na

    2016-01-01

    Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C–50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO4−• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO4−•, followed by a HF elimination process aided by •OH, which produces one-CF2-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn−1F2n−1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs. PMID:27322298

  12. Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions.

    PubMed

    Yin, Penghua; Hu, Zhihao; Song, Xin; Liu, Jianguo; Lin, Na

    2016-01-01

    Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C-50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO₄(-)• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO₄(-)•, followed by a HF elimination process aided by •OH, which produces one-CF₂-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn-1F2n-1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs. PMID:27322298

  13. Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions.

    PubMed

    Yin, Penghua; Hu, Zhihao; Song, Xin; Liu, Jianguo; Lin, Na

    2016-01-01

    Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C-50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO₄(-)• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO₄(-)•, followed by a HF elimination process aided by •OH, which produces one-CF₂-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn-1F2n-1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs.

  14. 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

  15. 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 ...

  16. 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,...

  17. Degradation kinetics and mechanism of aniline by heat-assisted persulfate oxidation.

    PubMed

    Xie, Xiaofang; Zhang, Yongqing; Huang, Weilin; Huang, Shaobing

    2012-01-01

    Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system (pH 3), while a high degradation rate was achieved at strong alkalinity (pH 11). Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5, 7 and 9). Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4'-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.

  18. In-situ chemical oxidation: Principle and applications of peroxide and persulfate treatments in wastewater systems.

    PubMed

    Devi, Parmila; Das, Umashankar; Dalai, Ajay K

    2016-11-15

    Hydrogen peroxide (H2O2) and persulfate are the most efficient and commonly used oxidants in in-situ chemical oxidation (ISCO) of organic contaminants. This review focuses on the principle and activation techniques used in H2O2 and persulfate based ISCO processes. It is crucial to understand the effect of activation techniques on process chemistry and free radicals behaviour in order to achieve high degradation efficiency. The chemistry of interaction of activated H2O2 and persulfate with organic contaminants is complex and many parameters influence the performance of ISCO processes, namely non-productive reactants, reaction intermediates, oxygen and pH. The poor understanding of interaction behaviour and reaction chemistry of oxidants with organic contaminants prevents the utilization of full potential of the process. Therefore, particular attention has been given to the factors affecting degradation efficiency and the performance of ISCO processes. Further, the mechanism of contaminant degradation using activated H2O2 and persulfate significantly differ from each other. The interaction of SO4(-) radical usually involves electron transfer reactions whereas HO radical involve electron-transfer and hydrogen-atom abstraction reactions. Moreover, the research gaps have been identified based on the knowledge of current research and recommendations are made for further understanding of ISCO processes. PMID:27453139

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

    PubMed

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

    2004-06-01

    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 (S2O8(2)-) 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). Experiments using Fe2+ as an activator under various molar ratios of S2O8(2)-/Fe2+/TCE in an aqueous system indicated that partial TCE degradation occurred almost instantaneously and then the reaction stalled. Either destruction of SO4-* in the presence of excess Fe2+ or the rapid conversion of all Fe2+ to Fe3+ limited the ultimate oxidizing capability of the system. Sequential addition of Fe2+ in small increments resulted in an increased TCE removal efficiency. Therefore, it appeared that Fe2+ played an important role in generating SO4-*. An observation of oxidation-reduction potential (ORP) variations revealed that the addition of sodium thiosulfate (Na2S2O3) to the ferrous ion activated persulfate system could significantly decrease the strong oxidizing conditions. It was hypothesized that the thiosulfate induced reducing conditions might convert Fe3+ to a lower valence state of Fe2+, making the Fe2+ available to activate persulfate decomposition. The sequential addition of thiosulfate (S2O3(2)-), after the initial stalling of ferrous ion activated persulfate oxidation of TCE, resulted in an improvement in TCE removal. The ferrous ion activated persulfate-thiosulfate redox couple resulted in fairly complete TCE degradation in aqueous systems in a short time frame. In soil slurry systems, TCE degradation was slower in comparison to aqueous systems.

  20. Remediation of Nitrobenzene Contaminated Soil by Combining Surfactant Enhanced Soil Washing and Effluent Oxidation with Persulfate

    PubMed Central

    Yan, Jingchun; Gao, Weiguo; Qian, Linbo; Han, Lu; Chen, Yun; Chen, Mengfang

    2015-01-01

    The combination of surfactant enhanced soil washing and degradation of nitrobenzene (NB) in effluent with persulfate was investigated to remediate NB contaminated soil. Aqueous solution of sodium dodecylbenzenesulfonate (SDBS, 24.0 mmol L-1) was used at a given mass ratio of solution to soil (20:1) to extract NB contaminated soil (47.3 mg kg-1), resulting in NB desorption removal efficient of 76.8%. The washing effluent was treated in Fe2+/persulfate and Fe2+/H2O2 systems successively. The degradation removal of NB was 97.9%, being much higher than that of SDBS (51.6%) with addition of 40.0 mmol L-1 Fe2+ and 40.0 mmol L-1 persulfate after 15 min reaction. The preferential degradation was related to the lone pair electron of generated SO4•−, which preferably removes electrons from aromatic parts of NB over long alkyl chains of SDBS through hydrogen abstraction reactions. No preferential degradation was observed in •OH based oxidation because of its hydrogen abstraction or addition mechanism. The sustained SDBS could be reused for washing the contaminated soil. The combination of the effective surfactant-enhanced washing and the preferential degradation of NB with Fe2+/persulfate provide a useful option to remediate NB contaminated soil. PMID:26266532

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

    PubMed

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

    2004-06-01

    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 contaminants. In this laboratory study persulfate oxidation of dissolved trichloroethylene (TCE) was investigated in aqueous and soil slurry systems under a variety of experimental conditions. A chelating agent (i.e., citric acid) was used in attempt to manipulate the quantity of ferrous ion in solution by providing an appropriate chelate/Fe2+ molar ratio. In an aqueous system a chelate/Fe2+ molar ratio of 1/5 (e.g., S2O8(2)-/chelate/Fe2+/TCE ratio of 20/2/10/1) was found to be the lowest acceptable ratio to maintain sufficient quantities of Fe2+ activator in solution resulting in nearly complete TCE destruction after only 20 min. The availability of Fe2+ appeared to be controlled by adjusting the molar ratio of chelate/Fe2+. In general, high levels of chelated ferrous ion concentrations resulted in faster TCE degradation and more persulfate decomposition. However, if initial ferrous ion contents are relatively low, sufficient quantities of chelate must be provided to ensure the chelation of a greater percentage of the limited ferrous ion present. Citric acid chelated ferrous ion appeared effective for TCE degradation within soil slurries but required longer reaction times. Additionally, the use of citric acid without the addition of supplemental Fe2+ in soil slurries, where the citric acid apparently extracted native metals from the soil, appeared to be somewhat effective at enhancing persulfate oxidation of TCE over extended reaction times. A comparison of different chelating agents revealed that citric acid was the most effective.

  2. 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.

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

    PubMed

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

    2016-02-01

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

  4. Bromate formation from bromide oxidation by the UV/persulfate process.

    PubMed

    Fang, Jing-Yun; Shang, Chii

    2012-08-21

    Bromate formation from bromide oxidation by the UV/persulfate process was investigated, along with changes in pH, persulfate dosages, and bromide concentrations in ultrapure water and in bromide-spiked real water. In general, the bromate formation increased with increasing persulfate dosage and bromide concentration. The bromate formation was initiated and primarily driven by sulfate radicals (SO(4)(•-)) and involved the formation of hypobromous acid/hypobromite (HOBr/OBr(-)) as an intermediate and bromate as the final product. Under the test conditions, the rate of the first step driven by SO(4)(•-) is slower than that of the second step. Direct UV photolysis of HOBr/OBr(-) to form bromate and the photolysis of bromate are insignificant. The bromate formation was similar for pH 4-7 but decreased over 90% with increasing pH from 7 to above 9. Less bromate was formed in the real water sample than in ultrapure water, which was primarily attributable to the presence of natural organic matter that reacts with bromine atoms, HOBr/OBr(-) and SO(4)(•-). The extent of bromate formation and degradation of micropollutants are nevertheless coupled processes unless intermediate bromine species are consumed by NOM in real water. PMID:22831804

  5. Effect of anions on the oxidation of organic compounds with ultrasonically activated persulfate

    NASA Astrophysics Data System (ADS)

    Sizykh, M. R.; Batoeva, A. A.

    2016-06-01

    The effect of anions typically present in natural and waste waters on the oxidation of the azo dye methyl orange with persulfate activated with high-frequency ultrasound was studied. At a chloride concentration of 1 mmol/L, the rate constant of substrate oxidation increased 1.5-fold, but further increase in the chloride content retarded the process. The addition of nitrates, carbonates, and hydrogen carbonates to the solution inhibited the process (NO 3 - < HCO 3 - ~ CO 3 2- ). These tendencies were in good agreement with the results obtained on a real water matrix of the natural surface water from Lake Baikal.

  6. 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.

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

    SciTech Connect

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

    2013-06-15

    Highlights: ► Ozone and persulfate reagent (O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) was used to treat stabilized leachate. ► Central composite design (CCD) with response surface methodology (RSM) was applied. ► Operating variables including ozone and persulfate dosage, pH variance, and reaction time. ► Optimum removal of COD, color, and NH{sub 3}–N was 72%, 96%, and 76%, respectively. ► A good value of ozone consumption (OC) obtained with 0.60 (kg O{sub 3}/kg COD). - Abstract: The objective of this study was to investigate the performance of employing persulfate reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and persulfate dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): COD, color, NH{sub 3}–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 210 min, 30 g/m{sup 3} ozone, 1 g/1 g COD{sub 0}/S{sub 2}O{sub 8}{sup 2-} ratio, and pH 10. The experimental results were corresponded well with predicted models (COD, color, and NH{sub 3}–N removal rates of 72%, 96%, and 76%, respectively, and 0.60 (kg O{sub 3}/kg COD OC). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as ozone only and persulfate S{sub 2}O{sub 8}{sup 2-} only, to evaluate its effectiveness. The combined method (i.e., O{sub 3}/S{sub 2}O{sub 8}{sup 2-}) achieved higher removal efficiencies for COD, color, and NH{sub 3}–N compared with other studied applications. Furthermore, the new method is more efficient than ozone/Fenton in advanced oxidation process in the treatment of the same studied leachate.

  8. 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 μm 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.

  9. Role of oxidants in enhancing dewaterability of anaerobically digested sludge through Fe (II) activated oxidation processes: hydrogen peroxide versus persulfate

    PubMed Central

    Song, Kang; Zhou, Xu; Liu, Yiqi; Gong, Yanyan; Zhou, Beibei; Wang, Dongbo; Wang, Qilin

    2016-01-01

    Improving dewaterability of sludge is important for the disposal of sludge in wastewater treatment plants (WWTPs). This study, for the first time, investigated the Fe(II) activated oxidization processes in improving anaerobically digested sludge (ADS) dewaterability. The combination of Fe(II) (0–100 mg/g total solids (TS)) and persulfate (0–1,000 mg/g TS) under neutral pH as well as the combination of Fe(II) (0–100 mg/g TS) and hydrogen peroxide (HP) (0–1,000 mg/g TS) under pH 3.0 were used to examine and compare their effect on the ADS dewaterability enhancement. The highest ADS dewaterability enhancement was attained at 25 mg Fe(II)/g TS and 50 mg HP/g TS, when the CST (CST: the capillary suction time, a sludge dewaterability indicator) was reduced by 95%. In contrast, the highest CST reduction in Fe(II)-persulfate conditioning was 90%, which was obtained at 50 mg Fe(II)/g TS and 250 mg persulfate/g TS. The results showed that Fe(II)-HP conditioning was comparable with Fe(II)-persulfate conditioning in terms of highest CST reduction. Economic analysis suggested that the Fe(II)-HP conditioning was more promising for improving ADS dewaterability compared with Fe(II)-persulfate conditioning, with the saving being up to $65,000 per year in a WWTP with a population equivalent of 100,000. PMID:27109500

  10. 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...

  11. 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.

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

    PubMed

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

    2015-11-01

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

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

    PubMed

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

    2015-11-01

    Graphene oxide (GO) and nano-sized zero-valent iron-reduced graphene oxide (nZVI-rGO) composite were prepared. The GO and nZVI-rGO composite were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The size of nZVI was about 6 nm as observed by TEM. The system of nZVI-rGO and persulfate (PS) was used for the degradation of trichloroethylene (TCE) in water, and showed 26.5% more efficiency as compared to nZVI/PS system. The different parameters were studied to determine the efficiency of nZVI-rGO to activate the PS system for the TCE degradation. By increasing the PS amount, TCE removal was also improved while no obvious effect was observed by varying the catalyst loading. Degradation was decreased as the TCE initial concentration was increased from 20 to 100 mg/L. Moreover, when initial solution pH was increased, efficiency deteriorated to 80%. Bicarbonate showed more negative effect on TCE removal among the solution matrix. To better understand the effects of radical species in the system, the scavenger tests were performed. The •SO4(-) and •O2(-) were predominant species responsible for TCE removal. The nZVI-rGO-activated PS process shows potential applications in remediation of highly toxic organic contaminants such as TCE present in the groundwater. Graphical abstract Persulfate activated by reduced graphene oxide and nano-sized zero-valent iron composite can be used for efficient degradation of trichloroethylene (TCE) in water. PMID:26162447

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

    PubMed

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

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

  15. 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.

  16. [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.

  17. Increased formation of halomethanes during chlorination of chloramphenicol in drinking water by UV irradiation, persulfate oxidation, and combined UV/persulfate pre-treatments.

    PubMed

    Wenhai, Chu; Tengfei, Chu; Erdeng, Du; Deng, Yang; Yingqing, Guo; Naiyun, Gao

    2016-02-01

    Ultraviolet/persulfate (UV/PS) has been widely used to generate sulfate radicals for degradation of water organic pollutants in previous studies. However, its impacts on disinfection byproduct formation during post-chlorination of degraded compounds is unclear. The objective of this study was to evaluate the impacts of UV irradiation, PS oxidation, and the combined UV/PS advanced oxidation process (AOP) pre-treatments on halomethane formation during the following chlorination of chloramphenicol (CAP), a model antibiotic commonly found in wastewater-impacted water. Results showed that CAP could be transformed to more trichloromethane (TCM) than monochloromethane (MCM) and dichloromethane (DCM) in the presence of excess chlorine. UV photolysis, PS oxidation and UV/PS AOP all directly decomposed CAP to produce halomethanes (HMs) before post-chlorination. Moreover, UV and UV/PS pre-treatments both enhanced the formation of all the HMs in the subsequent chlorination. PS pre-oxidation decreased the TCM formation during post-chlorination, but increased the yields of MCM, DCM and total HMs. UV pre-irradiation significantly increased the bromide utilization of HMs, whereas UV/PS pre-oxidation decreased the bromine incorporation and utilization of HMs from the chlorination of CAP in a low-bromide water. UV irradiation, PS oxidation, and UV/PS AOP can inactivate pathogens and degrade organic pollutants, but this benefit should be weighed against a potential risk of the increased halomethane formation from degraded organic pollutants with and without post-chlorination.

  18. Performance of combined sodium persulfate/H2O2 based advanced oxidation process in stabilized landfill leachate treatment.

    PubMed

    Hilles, Ahmed H; Abu Amr, Salem S; Hussein, Rim A; El-Sebaie, Olfat D; Arafa, Anwaar I

    2016-01-15

    A combination of persulfate and hydrogen peroxide (S2O8(2-)/H2O2) was used to oxidizelandfill leachate. The reaction was performed under varying S2O8(2-)/H2O2 ratio (g/g), S2O8(2-)/H2O2 dosages (g/g), pH, and reaction time (minutes), so as to determine the optimum operational conditions. Results indicated that under optimum operational conditions (i.e. 120 min of oxidation using a S2O8(2-)/H2O2 ratio of 1 g/1.47 g at a persulfate and hydrogen peroxide dosage of 5.88 g/50 ml and8.63 g/50 ml respectively, at pH 11) removal of 81% COD and 83% NH3-N was achieved. In addition, the biodegradability (BOD5/COD ratio) of the leachate was improved from 0.09 to 0.17. The results obtained from the combined use of (S2O8(2-)/H2O2) were compared with those obtained with sodium persulfate only, hydrogen peroxide only and sodium persulfate followed by hydrogen peroxide. The combined method (S2O8(2-)/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with the other methods using a single oxidizing agent. Additionally, the study has proved that the combination of S2O8(2-)/H2O2 is more efficient than the sequential use of sodium persulfate followed by hydrogen peroxide in advanced oxidation processes aiming at treatingstabilizedlandfill leachate.

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

    PubMed

    Li, Huanxuan; Wan, Jinquan; Ma, Yongwen; Wang, Yan

    2016-08-15

    This study investigated reaction pathway and oxidation mechanisms of dibutyl phthalate (DBP) by persulfate (PS) activated with zero-valent iron (ZVI). The DBP degradation was studied at three pH values (acidic, neutral and basic) in the presence of different organic scavengers. Using a chemical probe method, both sulfate radical (SO4(-)) and hydroxyl radical (·OH) were found to be primary oxidants at pH3.0 and pH7.0, respectively while ·OH was the major specie to oxidize DBP at pH11.0. A similar result was found in an experiment of Electron Spin Resonance spin-trapping where in addition to OH, superoxide radical (O2(-)) was detected at pH11.0. The transformation of degradation products including dimethyl phthalate (DMP), diethyl phthalate (DEP), phthalic anhydride, and acetophenone exhibited diverse variation during the reaction processes. The phthalic anhydride concentration appeared to be maximum at all pHs. Another eleven intermediate products were also found at pH3.0 by GC-MS and HPLC analysis, and their degradation mechanisms and pathways were proposed. It was suggested that dealkylation, hydroxylation, decarboxylation and hydrogen extraction were the dominant degradation mechanisms of DBP at pH3.0. PMID:27125682

  20. Oxidative degradation of diclofenac by thermally activated persulfate: implication for ISCO.

    PubMed

    Chen, Jiabin; Qian, Yajie; Liu, Hongmei; Huang, Tianyin

    2016-02-01

    Diclofenac (DCF), one of the typically recalcitrant pharmaceuticals, has been frequently detected in groundwater in recent years. This work investigated the performance of DCF degradation by thermally activated persulfate (PS) to further understand its application in in situ chemical oxidation (ISCO) for DCF-contaminated groundwater. The effects of various factors, including activation temperature, solution pH, PS/DCF ratio, and common constitutes, e.g., HCO3(-), Cl(-) and humic acid, and the toxicity of transformation products were evaluated. The results indicated that the oxidation of DCF was well-fitted with a pseudo-first-order kinetic model, and the rate constants increased with the elevated temperatures. The rate constants from 50-70 °C were further fitted to the Arrhenius equation, yielding an activation energy of 157.63 kJ·mol(-1). In addition, the oxidation of DCF was highly pH-dependent, with the rate constants rapidly decreased from pH 5 to 7, then slightly increased at the alkaline pH. The presence of a low dosage of Cl(-)(0-10 mM) promoted the degradation of DCF, whereas high Cl(-) addition (>10 mM) inhibited DCF degradation. HCO3(-) exhibited a negligible effect on DCF removal, while natural organic matters, e.g., humic acids, lightly inhibited DCF degradation. The rapid degradation of DCF was also confirmed in the real groundwater sample, which might be attributed to the pH drop during the reaction. Moreover, the radical quenching experiments revealed that sulfate radicals (SO4·-)) was the dominant reactive species for DCF oxidation. Finally, the acute toxicity of the DCF solution, as tested with a bioluminescent assay, was gradually decreased during the reaction, indicating that a thermally activated PS oxidation was a promising alternative approach for DCF-contaminated groundwater remediation.

  1. Efficient decomposition of environmentally persistent perfluorocarboxylic acids by use of persulfate as a photochemical oxidant.

    PubMed

    Hori, Hisao; Yamamoto, Ari; Hayakawa, Etsuko; Taniyasu, Sachi; Yamashita, Nobuyoshi; Kutsuna, Shuzo; Kiatagawa, Hiroshi; Arakawa, Ryuichi

    2005-04-01

    Photochemical decomposition of persistent perfluorocarboxylic acids (PFCAs) in water by use of persulfate ion (S2O8(2-)) was examined to develop a technique to neutralize stationary sources of PFCAs. Photolysis of S2O8(2-) produced highly oxidative sulfate radical anions (SO4-), which efficiently decomposed perfluorooctanoic acid (PFOA) and other PFCAs bearing C4-C8 perfluoroalkyl groups. The major products were F- and CO2; also, small amounts of PFCAs with shorter than initial chain lengths were detected in the reaction solution. PFOA at a concentration of 1.35 mM (typical of that in untreated wastewater after an emulsifying process in fluoropolymer manufacture) was completely decomposed by a photochemical system with 50 mM S2O8(2-) and 4 h of irradiation from a 200-W xenon-mercury lamp. The initial PFOA decomposition rate was 11 times higherthan with photolysis alone. All sulfur-containing species in the reaction solution were eventually transformed to sulfate ions by this method. This method was successfully applied to the decomposition of perfluorononanoic acid contained in a floor wax solution.

  2. 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.

  3. Degradation efficiencies of azo dye Acid Orange 7 by the interaction of heat, UV and anions with common oxidants: persulfate, peroxymonosulfate and hydrogen peroxide.

    PubMed

    Yang, Shiying; Wang, Ping; Yang, Xin; Shan, Liang; Zhang, Wenyi; Shao, Xueting; Niu, Rui

    2010-07-15

    In this paper, the degradation of azo dye Acid Orange 7 (AO7) by three common peroxides (persulfate (PS), peroxymonosulfate (PMS) or hydrogen peroxide (H(2)O(2))) under various activation conditions, i.e., heat (25-80 degrees C), UV light (254 nm), or anions (SO(4)(2-), NO(3)(-), CO(3)(2-), HCO(3)(-), HPO(4)(2-), and Cl(-)), was investigated. The order of AO7 degradation efficiencies by heat activation is PS>PMS>H(2)O(2). PS oxidation activated by heat (>50 degrees C) is an effective degradation technology, while PMS and H(2)O(2) are hardly activated. When assisted by UV, peroxides could all be activated and degrade AO7 quickly. The order is PS>H(2)O(2)>PMS. We activated peroxides, for the first time, by using some anions and compared the subsequently degradation efficiencies of AO7. It was found that PMS could be activated by some anions, but PS and H(2)O(2) cannot. The activation efficiencies of PMS by SO(4)(2-) and NO(3)(-) are negligible, whereas remarkable by HCO(3)(-), HPO(4)(2-), Cl(-) and CO(3)(2-). For HCO(3)(-), HPO(4)(2-) and Cl(-), the activation efficiencies become higher with the increase of anion concentration. For CO(3)(2-), however, the activation efficiency is higher at lower concentration.

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

    PubMed

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

    2016-01-19

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

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

    PubMed

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

    2016-06-01

    The transformation efficiency and products of an odorous compound 2,4,6-trichloroanisole (TCA) at the wavelength of 254 nm in the presence of persulfate were investigated for the first time. The effects of water matrix (i.e., natural organic matter (NOM), pH, carbonate/bicarbonate (HCO3(-)/CO3(2-)), and chloride ions (Cl(-))) were evaluated. The second order rate constant of TCA reacting with sulfate radical (SO4(-)) was determined to be (3.72 ± 0.10) × 10(9) M(-1) s(-1). Increasing dosage of persulfate increased the observed pseudo-first-order rate constant for TCA degradation (kobs), and the contribution of SO4(-) to TCA degradation was much higher than that of HO at each experimental condition. Degradation rate of TCA decreased with pH increasing from 4.0 to 9.0, which could be explained by the lower radical scavenging effect of dihydrogen phosphate than hydrogen phosphate in acidic condition (pH < 6). NOM significantly decreased kobs due to the effects of radical scavenging and UV absorption with the former one being dominant. kobs decreased from 2.32 × 10(-3) s(-1) to 0.92 × 10(-3) s(-1) with the CO3(2-)/HCO3(-) concentration increased from 0.5 mM to 10 mM in the UV/persulfate process, while kobs slightly decreased from 2.54 × 10(-3) s(-1) in the absence of Cl(-) to 2.10 × 10(-3) s(-1) in the presence of 10 mM Cl(-). Most of these kinetic results could be described by a steady-state kinetic model. Furthermore, liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry at powerful precursor ion scan approach was used to selectively detect oxidation products of TCA. It was found that 2,4,6-trichorophenol (TCP) was the major oxidation product (i.e., the initial yield of TCP was above 90%). The second order rate constant between TCP and SO4(-) was estimated to be (4.16 ± 0.20) × 10(9) M(-1) s(-1). In addition, three products (i.e., 2,6-dichloro-1,4-benzoquinone and two aromatic ring-opening products

  6. Persulfate persistence under thermal activation conditions.

    PubMed

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

    2008-12-15

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

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

    PubMed

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

    2012-11-01

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

  8. Selective oxidative degradation of toluene for the recovery of surfactant by an electro/Fe²⁺/persulfate process.

    PubMed

    Long, Anhua; Zhang, Hui

    2015-08-01

    An electro/Fe(2+)/persulfate process has been conducted for toluene removal from surfactant (SDS) flushing solution, and the pseudo-second-order reaction rate constant (k2 value) of toluene removal has been optimized by a response surface methodology (RSM). The results indicated that in this process, the reaction between persulfate and externally added Fe(2+) generates sulfate-free radicals, and at the same time, Fe(2+) is electro-regenerated at the cathode by the reduction of Fe(3+). RSM based on Box-Behnken design (BBD) has been applied to analyze the experimental variables, of which the concentrations of persulfate and Fe(2+) showed a positive effect on the rate constant of toluene removal, whereas the concentration of SDS showed a negative effect. The interactions between pairs of variables proved to be significant, such as between SDS, persulfate, and Fe(2+) concentrations. ANOVA results confirmed that the proposed models were accurate and reliable for analysis of the variables of the electro/Fe(2+)/persulfate process. The shapes of the 3D response surfaces and contour plots showed that the SDS, persulfate, and Fe(2+) concentrations substantially affected the k2 value of toluene removal. The results indicated that increasing persulfate or Fe(2+) concentration increased the k2 value, whereas increasing SDS concentration decreased the k2 value. The reaction intermediates have been identified by GC-MS, and a plausible degradation pathway for toluene degradation is proposed.

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

    PubMed

    Liang, Chenju; Lee, I-Ling

    2008-09-10

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

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

    EPA Science Inventory

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

  11. 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...

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

    PubMed

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

    2014-01-01

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

  13. 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.

  14. Effect of metal oxides on the reactivity of persulfate/Fe(II) in the remediation of diesel-contaminated soil and sand.

    PubMed

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

    2010-10-15

    The effect of metal oxides on the ability of persulfate (PS) with Fe(II) to remediate diesel-contaminated soil was investigated. In both natural soil and purchased sand, the highest diesel degradation occurred at pH 3 and the optimum molar ratio of PS/Fe(II) was 100:1 (i.e. 500 mM PS to 5 mM Fe(II)). Moreover, adding Fe(II) increased PS reactivity more in soil than it did in sand, indicating the involvement of metal oxides in the soil matrix. Evaluating the effects of metal oxides (i.e. goethite, hematite, magnetite, and manganese oxide) on the reactivity of PS with/without Fe(II) in a system containing diesel-contaminated sand revealed that manganese oxide increased PS activity the most and that the highest diesel degradation by PS occurred when both manganese oxide and Fe(II) were used as activators. XRD did not show the transformation of manganese oxide in the presence of Fe(II). SEM-EDS showed the association of Fe(II) on the surface of manganese oxide, and ICP analysis revealed that almost all the added Fe(II) adsorbed to manganese oxide but almost none adsorbed to iron oxides under acidic conditions. Therefore, the high reactivity of PS could be due to the high density of Fe(II) over the surface of manganese oxide.

  15. Oxidation of 2,4-dichlorophenol by non-radical mechanism using persulfate activated by Fe/S modified carbon nanotubes.

    PubMed

    Cheng, Xin; Guo, Hongguang; Zhang, Yongli; Liu, Yang; Liu, Hongwei; Yang, Ying

    2016-05-01

    The aim of this study was to develop a new approach for the activation of persulfate (PS) based on carbon nanotubes (CNTs). Fe/S modified carbon nanotubes (Fe/S-CNTs) were synthesized via impregnation-precipitation in the aqueous-phase synthesis method. The morphologies and chemical states of the catalysts were characterized and 2,4-dichlorophenol (2,4-DCP) was selected to investigate the degradation performance using Fe/S-CNTs with PS. The results reveal that the Fe/S-CNTs catalysts can significantly accelerate the removal of 2,4-DCP compared to single PS or PS/CNTs. The catalytic capacity is also enhanced by S modification and is affected by the solution pH. The iron loading content, PS concentration and catalyst dosage could play important roles in the degradation. A non-radical process of 2,4-DCP degradation is demonstrated for the first time in the results of the radical scavengers and chloride ionic, as well as persulfate decomposition. It is suggested that PS is first bonded with the sp(2)-hybridized system and activated by iron oxide particles and iron-sulfur complexes, then it reacts rapidly with the adsorbed 2,4-DCP. PMID:26897564

  16. A rapid spectrophotometric determination of persulfate anion in ISCO.

    PubMed

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

    2008-11-01

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

  17. Activation of persulfate by quinones: free radical reactions and implication for the degradation of PCBs.

    PubMed

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

    2013-05-01

    There has been considerable interest in the use of persulfate for in situ chemical oxidation of organic contaminants in soils, sediments, and groundwater. Since humic acid (HA) exists ubiquitously in these environmental compartments, its redox active functional moieties, such as quinones, may play an important role in the oxidation processes of persulfate treatments. Understanding the effects of HA, especially the quinone functional groups on the degradation of pollutants by persulfate and the production of sulfate radicals (SO4(•-)) from persulfate, is beneficial for devising effective and economically feasible remediation strategies. In this study, the effects of model quinone compounds and HA on the degradation of 2,4,4'-trichlorobiphenyl (PCB28) by persulfate and the production of SO4(•-) from persulfate were investigated. It was found that quinones and HA can efficiently activate persulfate for the degradation of PCB28. The mechanism of persulfate activation was elucidated by quenching and electron paramagnetic resonance (EPR) studies. The results indicated that production of SO4(•-) from persulfate and quinones was semiquinone radical-dependent. The effects of quinone concentrations were also studied. The findings of this study elucidated a new pathway of persulfate activation, which could degrade environmental contaminants efficiently and provide useful information for the remediation of contaminated soil and water by persulfate.

  18. Hg0 absorption in potassium persulfate solution*

    PubMed Central

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

    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 by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate (SN), temperature, Hg0 concentration in the reactor inlet and tertiary butanol (TBA), free radical scavenger, on the removal efficiency of Hg0 were studied. The results showed that the removal efficiency of Hg0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed. PMID:16615172

  19. Persulfate injection into a gasoline source zone.

    PubMed

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

    2013-07-01

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

  20. 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.

  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. Mechanistic study of photo-oxidation of Bisphenol-A (BPA) with hydrogen peroxide (H2O2) and sodium persulfate (SPS).

    PubMed

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

    2016-01-15

    The removal of Bisphenol-A (BPA) from contaminated water using advanced oxidation methods such as UV-C assisted oxidation by hydrogen peroxide (H2O2) and sodium persulfate (SPS) has been reported by the authors earlier (Sharma et al., 2015a). In the present study, the authors report the removal of BPA from aqueous solution by the above two methods and its degradation mechanism. UV-C light (254 nm wavelength, 40 W power) was applied to BPA contaminated water at natural pH (pHN) under room temperature conditions. Experiments were carried out with the initial BPA concentration in the range of 0.04 mM-0.31 mM and the oxidant/BPA molar ratio in the range of 294:1-38:1 for UV-C/H2O2 and 31.5-4.06:1 for UV-C/SPS systems. The removal of BPA enhanced with decreasing BPA concentration. The total organic carbon also decreased with the UV-C irradiation time under optimum conditions ([H2O2]0 = 11.76 mM; [SPS]0 = 1.26 mM; temperature (29 ± 3 °C). Competition of BPA for reaction with HO or [Formula: see text] radicals at its higher concentrations results in a decrease in the removal of BPA. The intermediates with smaller and higher molecular weights than that of BPA were found in the treated water. Based on GC-MS and FTIR spectra of the reaction mixture, the formation of hydroxylated by-products testified the HO mediated oxidation pathway in the BPA degradation, while the formation of quinones and phenoxy phenols pointed to the [Formula: see text] dominating pathway through the formation of hydroxycyclohexadienyl (HCHD) and BPA phenoxyl radicals. The main route of BPA degradation is the hydroxylation followed by dehydration, coupling and ring opening reactions.

  3. Mechanistic study of photo-oxidation of Bisphenol-A (BPA) with hydrogen peroxide (H2O2) and sodium persulfate (SPS).

    PubMed

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

    2016-01-15

    The removal of Bisphenol-A (BPA) from contaminated water using advanced oxidation methods such as UV-C assisted oxidation by hydrogen peroxide (H2O2) and sodium persulfate (SPS) has been reported by the authors earlier (Sharma et al., 2015a). In the present study, the authors report the removal of BPA from aqueous solution by the above two methods and its degradation mechanism. UV-C light (254 nm wavelength, 40 W power) was applied to BPA contaminated water at natural pH (pHN) under room temperature conditions. Experiments were carried out with the initial BPA concentration in the range of 0.04 mM-0.31 mM and the oxidant/BPA molar ratio in the range of 294:1-38:1 for UV-C/H2O2 and 31.5-4.06:1 for UV-C/SPS systems. The removal of BPA enhanced with decreasing BPA concentration. The total organic carbon also decreased with the UV-C irradiation time under optimum conditions ([H2O2]0 = 11.76 mM; [SPS]0 = 1.26 mM; temperature (29 ± 3 °C). Competition of BPA for reaction with HO or [Formula: see text] radicals at its higher concentrations results in a decrease in the removal of BPA. The intermediates with smaller and higher molecular weights than that of BPA were found in the treated water. Based on GC-MS and FTIR spectra of the reaction mixture, the formation of hydroxylated by-products testified the HO mediated oxidation pathway in the BPA degradation, while the formation of quinones and phenoxy phenols pointed to the [Formula: see text] dominating pathway through the formation of hydroxycyclohexadienyl (HCHD) and BPA phenoxyl radicals. The main route of BPA degradation is the hydroxylation followed by dehydration, coupling and ring opening reactions. PMID:26468603

  4. Ultrasound and heat enhanced persulfate oxidation activated with Fe(0) aggregate for the decolorization of C.I. Direct Red 23.

    PubMed

    Weng, Chih-Huang; Tsai, Kuen-Lung

    2016-03-01

    Effluents from the paper printing and textile industries are often heavily contaminated with azo dyes. Azo dyes are difficult to oxidize biologically. This work investigated the decolorization of an azo dye, C.I. Direct Red 23 (DR23), by persulfate (PS) activated with Fe(0) aggregates (PS/Fe(0)). Ultrasound (US) and heat were used as enhancement tools in the PS oxidation system. Neither US-activated PS nor thermally activated PS was effective in oxidizing DR23. However, the decolorization was significantly enhanced by PS/Fe(0) combined with US (PS/Fe(0)/US) or heat (PS/Fe(0)/55 °C). Approximately 95% decolorization of 1×10(-4) M DR23 was achieved within 15 min in the PS/Fe(0)/US system at an initial pH of 6.0, PS of 5×10(-3) M, Fe(0) of 0.5 g/L and US irradiation of 106 W/cm(2) (60 kHz). Complete decolorization was achieved within 10 min in the Fe(0)/PS/55 °C system. The rate of decolorization doubled when US was introduced in the PS/Fe(0) system during the treatment of different initial dye concentrations. The dependence of dye and true color (ADMI) depletion on PS concentration has been discussed. DR23 was completely degraded based on the disappearance of aromatic groups of UV-vis spectra and the variation of TOC mineralization. The observed pseudo-first-order decolorization rate was substantially enhanced by increasing temperature. The Arrhenius activation energy for the PS activated with Fe(0) was estimated as 8.98 kcal/mol, implying that higher temperature is beneficial for the DR23 decolorization. The addition of US into the PS/Fe(0) system did not incur a substantial increase in electricity, whereas the mineralization of DR23 occurred quickly. Thus, both PS/Fe(0)/US and heated PS/Fe(0) systems are practically feasible for the effective degradation of the direct azo dye in textile wastewater. PMID:26584979

  5. 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...

  6. Electrokinetic delivery of persulfate to remediate PCBs polluted soils: Effect of different activation methods.

    PubMed

    Fan, Guangping; Cang, Long; Gomes, Helena I; Zhou, Dongmei

    2016-02-01

    Persulfate-based in-situ chemical oxidation (ISCO) for the remediation of organic polluted soils has gained much interest in last decade. However, the transportation of persulfate in low-permeability soil is very low, which limits its efficiency in degrading soil pollutants. Additionally, the oxidation-reduction process of persulfate with organic contaminants takes place slowly, while, the reaction will be greatly accelerated by the production of more powerful radicals once it is activated. Electrokinetic remediation (EK) is a good way for transporting persulfate in low-permeability soil. In this study, different activation methods, using zero-valent iron, citric acid chelated Fe(2+), iron electrode, alkaline pH and peroxide, were evaluated to enhance the activity of persulfate delivered by EK. All the activators and the persulfate were added in the anolyte. The results indicated that zero-valent iron, alkaline, and peroxide enhanced the transportation of persulfate at the first stage of EK test, and the longest delivery distance reached sections S4 or S5 (near the cathode) on the 6th day. The addition of activators accelerated decomposition of persulfate, which resulted in the decreasing soil pH. The mass of persulfate delivered into the soil declined with the continuous decomposition of persulfate by activation. The removal efficiency of PCBs in soil followed the order of alkaline activation > peroxide activation > citric acid chelated Fe(2+) activation > zero-valent iron activation > without activation > iron electrode activation, and the values were 40.5%, 35.6%, 34.1%, 32.4%, 30.8% and 30.5%, respectively. The activation effect was highly dependent on the ratio of activator and persulfate.

  7. Electrokinetic delivery of persulfate to remediate PCBs polluted soils: Effect of different activation methods.

    PubMed

    Fan, Guangping; Cang, Long; Gomes, Helena I; Zhou, Dongmei

    2016-02-01

    Persulfate-based in-situ chemical oxidation (ISCO) for the remediation of organic polluted soils has gained much interest in last decade. However, the transportation of persulfate in low-permeability soil is very low, which limits its efficiency in degrading soil pollutants. Additionally, the oxidation-reduction process of persulfate with organic contaminants takes place slowly, while, the reaction will be greatly accelerated by the production of more powerful radicals once it is activated. Electrokinetic remediation (EK) is a good way for transporting persulfate in low-permeability soil. In this study, different activation methods, using zero-valent iron, citric acid chelated Fe(2+), iron electrode, alkaline pH and peroxide, were evaluated to enhance the activity of persulfate delivered by EK. All the activators and the persulfate were added in the anolyte. The results indicated that zero-valent iron, alkaline, and peroxide enhanced the transportation of persulfate at the first stage of EK test, and the longest delivery distance reached sections S4 or S5 (near the cathode) on the 6th day. The addition of activators accelerated decomposition of persulfate, which resulted in the decreasing soil pH. The mass of persulfate delivered into the soil declined with the continuous decomposition of persulfate by activation. The removal efficiency of PCBs in soil followed the order of alkaline activation > peroxide activation > citric acid chelated Fe(2+) activation > zero-valent iron activation > without activation > iron electrode activation, and the values were 40.5%, 35.6%, 34.1%, 32.4%, 30.8% and 30.5%, respectively. The activation effect was highly dependent on the ratio of activator and persulfate. PMID:26347936

  8. Optimization of leachate treatment using persulfate/H2O2 based advanced oxidation process: case study: Deir El-Balah Landfill Site, Gaza Strip, Palestine.

    PubMed

    Hilles, Ahmed H; Abu Amr, Salem S; Hussein, Rim A; Arafa, Anwar I; El-Sebaie, Olfat D

    2016-01-01

    The objective of this study was to investigate the performance of employing H2O2 reagent in persulfate activation to treat stabilized landfill leachate. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as persulfate and H2O2 dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following two responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD) and NH3-N removal. The obtained optimum conditions included a reaction time of 116 min, 4.97 g S2O8(2-), 7.29 g H2O2 dosage and pH 11. The experimental results were corresponding well with predicted models (COD and NH3-N removal rates of 81% and 83%, respectively). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as persulfate only and H2O2 only, to evaluate its effectiveness. The combined method (i.e., /S2O8(2-)/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with other studied applications. PMID:26744940

  9. 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.

  10. In-situ Activation of Persulfate by Iron Filings and Degradation of 1,4-dioxane

    PubMed Central

    Zhong, Hua; Brusseau, Mark L; Wang, Yake; Yan, Ni; Quig, Lauren; Johnson, Gwynn R

    2015-01-01

    Activation of persulfate by iron filings and subsequent degradation of 1,4-dioxane (dioxane) was studied in both batch-reactor and column systems to evaluate the potential of a persulfate-enhanced permeable reactive barrier (PRB) system for combined oxidative-reductive removal of organic contaminants from groundwater. In batch experiments, decomposition of persulfate to sulfate and degradation of dioxane both occurred rapidly in the presence of iron filings. Conversely, dioxane degradation by persulfate was considerably slower in the absence of iron filings. For the column experiments, decomposition and retardation of persulfate was observed for transport in the columns packed with iron filings, whereas no decomposition or retardation was observed for transport in columns packed with a reference quartz sand. Both sulfate production and dioxane degradation were observed for the iron-filings columns, but not for the sand column. The pH of the column effluent increased temporarily before persulfate breakthrough, and significant increases in both ferrous and ferric iron coincided with persulfate breakthrough. Multiple species of free radicals were produced from persulfate activation as determined by electron paramagnetic resonance (EPR) spectroscopy. The impact of the oxidation process on solution composition and iron-filings surface chemistry was examined using ICP-MS, SEM-EDS, and XRD analyses. A two-stage reaction mechanism is proposed to describe the oxidation process, consisting of a first stage of rapid, solution-based, radical-driven, decomposition of dioxane and a second stage governed by rate-limited surface reaction. The results of this study show successful persulfate activation using iron filings, and the potential to apply an enhanced PRB method for improving in-situ removal of organic contaminants from groundwater. PMID:26141426

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

    PubMed

    Yan, Dickson Y S; Lo, Irene M C

    2013-07-01

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

  12. Activation of Persulfates by Graphitized Nanodiamonds for Removal of Organic Compounds.

    PubMed

    Lee, Hongshin; Kim, Hyoung-Il; Weon, Seunghyun; Choi, Wonyong; Hwang, Yu Sik; Seo, Jiwon; Lee, Changha; Kim, Jae-Hong

    2016-09-20

    This study introduces graphited nanodiamond (G-ND) as an environmentally friendly, easy-to-regenerate, and cost-effective alternative catalyst to activate persulfate (i.e., peroxymonosulfate (PMS) and peroxydisulfate (PDS)) and oxidize organic compounds in water. The G-ND was found to be superior for persulfate activation to other benchmark carbon materials such as graphite, graphene, fullerene, and carbon nanotubes. The G-ND/persulfate showed selective reactivity toward phenolic compounds and some pharmaceuticals, and the degradation kinetics were not inhibited by the presence of oxidant scavengers and natural organic matter. These results indicate that radical intermediates such as sulfate radical anion and hydroxyl radical are not majorly responsible for this persulfate-driven oxidation of organic compounds. The findings from linear sweep voltammetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectroscopy analyses suggest that the both persulfate and phenol effectively bind to G-ND surface and are likely to form charge transfer complex, in which G-ND plays a critical role in mediating facile electron transfer from phenol to persulfate. PMID:27589608

  13. Remediation of hexachlorocyclohexanes by electrochemically activated persulfates.

    PubMed

    Wacławek, Stanisław; Antoš, Vojtech; Hrabák, Pavel; Černík, Miroslav; Elliott, Daniel

    2016-01-01

    Hexachlorocyclohexane (HCH) isomers represent a family of formerly widely utilized pesticides that are persistent, capable of undergoing long-range transport and tend to bioaccumulate in human and animal tissue. Their widespread global utilization coupled with a propensity to adversely impact human health and the environment translates into an urgent need to develop feasible methodologies by which to treat HCH-impacted groundwater and soil. The present study was conducted to evaluate the efficacy of two persulfate-based oxidants: peroxydisulfate (S2O8 (2-), PDS) and peroxymonosulfate (HSO5 (-), PMS) activated by electrochemical processes (EC) to treat HCH-impacted environmental media. This research demonstrated that the optimal experimental conditions (oxidant dose and electrical current) were 2 mM PDS and 20 mA for an aqueous solution of 4 μM of summed HCHs (ΣHCH). GC/MS full scan analysis revealed the presence of 2,4,6-trichlorophenol as the only detectable intermediate formed during electro-activated PDS treatment of ΣHCH. The investigated method was tested on leachate from a known HCHs-impacted site in Hajek, Czech Republic which contained 106 μg/l of ΣHCH and 129 μg/l of chlorobenzenes. Results from batch treatment showed positive results for electro-activated PDS but only negligible effectiveness for electro-activated PMS. In addition to explaining the efficacy of the electro-activated PDS, this research also explored the basis for the differing reactivities of these two persulfates.

  14. 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.

  15. 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

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

    PubMed

    Wang, Zhen; Deng, Dayi; Yang, Liling

    2014-04-30

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

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

    PubMed Central

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

    2014-01-01

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

  18. 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.

  19. 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.

  20. Final report on the safety assessment of Ammonium, Potassium, and Sodium Persulfate.

    PubMed

    Pang, S; Fiume, M Z

    2001-01-01

    Ammonium, Potassium, and Sodium Persulfate are inorganic salts used as oxidizing agents in hair bleaches and hair-coloring preparations. Persulfates are contained in hair lighteners at concentrations up to 60%, in bleaches and lighteners at up to 22% and 16%, respectively, and in off-the-scalp products used to highlight hair strands at up to 25%. They are used in professional product bleaches and lighteners at similar concentrations. Much of the available safety test data are for Ammonium Persulfate, but these data are considered applicable to the other salts as well. Acute dermal, oral, and inhalation toxicity studies are available, but only the latter are remarkable, with gross lesions observed in the lungs, liver, stomach, and spleen. In short-term and subchronic feeding studies the results were mixed; some studies found no evidence of toxicity and others found local damage to the mucous membrane in the gastrointestinal tract, but no other systemic effects. Short-term inhalation toxicity was observed when rats were exposed to aerosolized Ammonium Persulfate at concentrations of 4 mg/m3 and greater. Ammonium Persulfate (as a moistened powder) was not an irritant to intact rabbit skin, but was sensitizing (in a saline solution) to the guinea pig. It was slightly irritating to rabbit eyes. Ammonium Persulfate was negative in the Ames test and the chromosomal aberration test. No significant evidence of tumor promotion or carcinogenicity was observed in studies of rats receiving topical applications of Ammonium Persulfate. The persulfates were reported to cause both delayed-type and immediate skin reactions, including irritant dermatitis, allergic eczematous dermatitis, localized contact urticaria, generalized urticaria, rhinitis, asthma, and syncope. The most common causes of allergic dermatitis in hairdressers are the active ingredients in hair dyes, and Ammonium Persulfate has been identified as a frequent allergen. A sensitization study that also examined the

  1. 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 μM) 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

  2. 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.

  3. Specific Inhalation Challenge in Persulfate Asthma.

    PubMed

    Hagemeyer, O; Marek, E; van Kampen, V; Sander, I; Raulf, M; Merget, R; Brüning, T

    2015-01-01

    Specific inhalation challenge (SIC) may be considered the 'gold standard' for the diagnosis of occupational asthma due to persulfate salts. The aim of the study was to develop a safe SIC protocol. Between 2003 and 2014, eight patients with suspected occupational asthma due to persulfate salts were examined (7 females, all hair-dressers). SIC was done with a dosimeter and a nebulizer using ammonium persulfate dissolved in phosphate buffer. Until 2009, a four-step-protocol (doses: 0.0004, 0.0045, 0.045, 0.45 mg; cumulative: 0.5 mg) was used, afterwards a six-step-protocol (doses: 0.0004, 0.0018, 0.007, 0.028, 0.113, 0.45 mg; cumulative: 0.6 mg). With each SIC protocol, four subjects were tested. Skin prick tests with ammonium persulfate (20 mg/mL) were performed in all and patch tests in four subjects. In total, four subjects showed a positive SIC, two with each protocol. All subjects showed an isolated late reaction. The greatest decrease of volume in 1 s was 35 % about 3.5 h after the last inhalation (four-step-protocol). Skin prick test with ammonium persulfate was positive in one SIC positive (2 mm wheal) and in two SIC negative patients (3 and 4 mm wheal). All four subjects tested with patch tests showed a positive reaction; three of them were SICpos. We recommend to include patch-testing in the diagnosis of suspected occupational asthma due to persulfate salts. Isolated late asthmatic reactions may occur after SIC. The proposed six-step SIC protocol was safe in this limited number of subjects. PMID:26022895

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

    PubMed

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

    2014-02-15

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

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

    PubMed

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

    2012-10-01

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

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

    PubMed

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

    2012-10-01

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

  7. Persulfate hair bleach reactions. Cutaneous and respiratory manifestations.

    PubMed

    Fisher, A A; Dooms-Goossens, A

    1976-10-01

    Ammonium persulfate is widely used to "boost" peroxide hair bleaches. These persulfates can produce a variety of cutaneous and respiratory responses, including allergic eczematous contact dermatitis, irritant dermatitis, localized edema, generalized urticaria, rhinitis, asthma, and syncope. Some of these reactions appear to be truly allergic while others appear to be due to the release of histamine on a nonallergic basis. Patch tests may be performed with 2% to 5% aqueous solution of ammonium persulfate. Scratch tests may result in asthma and syncope. In some patients, merely rubbing a saturated solution of ammonium persulfate into the skin will evoke a large urticarial wheal. Hairdressers should be made aware that these ammonium persulfate hair bleach preparations may provoke severe reactions and should seek medical attention if the client complains of severe itching, tingling, a burning sensation, hives, dizziness, or weakness.

  8. Persulfate hair bleach reactions. Cutaneous and respiratory manifestations.

    PubMed

    Fisher, A A; Dooms-Goossens, A

    1976-10-01

    Ammonium persulfate is widely used to "boost" peroxide hair bleaches. These persulfates can produce a variety of cutaneous and respiratory responses, including allergic eczematous contact dermatitis, irritant dermatitis, localized edema, generalized urticaria, rhinitis, asthma, and syncope. Some of these reactions appear to be truly allergic while others appear to be due to the release of histamine on a nonallergic basis. Patch tests may be performed with 2% to 5% aqueous solution of ammonium persulfate. Scratch tests may result in asthma and syncope. In some patients, merely rubbing a saturated solution of ammonium persulfate into the skin will evoke a large urticarial wheal. Hairdressers should be made aware that these ammonium persulfate hair bleach preparations may provoke severe reactions and should seek medical attention if the client complains of severe itching, tingling, a burning sensation, hives, dizziness, or weakness. PMID:962335

  9. Activated persulfate for organic chemical degradation: A review.

    PubMed

    Matzek, Laura W; Carter, Kimberly E

    2016-05-01

    Activated persulfate reactions have widespread application for groundwater and environmental remediation, as many of these reactions involve destruction of environmental contaminants. Within the last five years, knowledge of activated persulfate degradation reactions has grown to include novel means of activating persulfate for enhanced removal of organic species. These current studies cover a long list of organic analytes, including pharmaceuticals, pesticides, halogenated compounds and dyes. An extensive review of recently published experimental parameters and results for the destruction of organic compounds via activated persulfate is presented. Focus is placed on emerging methodologies and manipulation of traditional activation techniques. Knowledge gaps are identified and discussed, as despite the number of publications on this subject, more broad-reaching guidelines are needed for optimizing applications of activated persulfate in water treatment.

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

    PubMed

    Al-Shamsi, Mohammed Ahmad; Thomson, Neil R

    2013-10-01

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

  11. Removal of 1,1,1-trichloroethane from aqueous solution by a sono-activated persulfate process.

    PubMed

    Li, Bingzhi; Li, Lin; Lin, Kuangfei; Zhang, Wei; Lu, Shuguang; Luo, Qishi

    2013-05-01

    1,1,1-Trichloroethane (TCA), labeled as a priority pollutant by the Environmental Protection Agency (EPA) of China, can be removed from groundwater by sonochemical oxidation. The sonochemical oxidation of TCA in the presence of persulfate (PS) showed a significant synergistic effect. The operational parameters, ultrasonic frequency, PS/TCA molar ratio, radical scavenger, inorganic anions (Cl(-), CO(3)(2-), HCO(3)(-) and NO(3)(-)) and humic acid (HA), were evaluated during the investigation of the sonochemical reaction. The results showed that the degradation of TCA followed pseudo-first-order kinetics, and the rate constant was found to increase with increasing ultrasonic frequency but to decrease with both an increasing PS/TCA molar ratio and an increasing concentration of inorganic anions. With a concentration of 4.46mg/L of HA in solution, an enhanced effect was observed. Further addition of HA retarded the degradation rate of TCA. TCA could be eliminated almost completely by sono-activated persulfate oxidation, with sulfate and hydroxyl radicals serving as the principal oxidants as confirmed by the addition of radical scavengers. Eleven chlorinated degradation intermediates were detected and quantified by purge and trap gas chromatography coupled with mass spectrometry (P&T-GC-MS) in the absence of pH buffer. Three TCA degradation pathways were therefore proposed. In conclusion, the sono-activated persulfate oxidation process appears to be a highly promising technique for the remediation of TCA-contaminated groundwater.

  12. Stoichiometric network analysis of the oxalate-persulfate-silver oscillator

    NASA Astrophysics Data System (ADS)

    Clarke, Bruce L.

    1992-08-01

    This paper illustrates an approach that can refine mechanisms and obtain information about rate constants from dynamical phase diagrams which show the regions of oscillation of a mechanism as a function of the experimental parameters. Possible mechanisms for the experimentally oscillating oxalate-persulfate-silver system are examined. Starting with a proposed mechanism by Ouyang and de Kepper, which they could not make oscillate, we show that some variations of the mechanism are stable for all nonnegative values of the rate constants. Other variations are unstable. For these variations, feedback cycles that lead to instability are compared with a conceptual picture of feedback in the experimental system. One unstable mechanism fits the picture well. Its unimportant reactions are omitted and an analytical solution for the unstable region using 13 adjustable parameters is obtained. The rate constants are adjusted to match this solution to the experimentally measured phase diagram. A good fit can only be obtained if [O2] is too low and k1 is much smaller than the known value. Both discrepancies are resolved if Ag2+ oxidizes water. The analysis predicts the width of the unstable region can increase when more O2 enters the reactor.

  13. Rate of phosphoantimonylmolybdenum blue complex formation in acidic persulfate digested sample matrix for total dissolved phosphorus determination: importance of post-digestion pH adjustment.

    PubMed

    Huang, Xiao-Lan; Zhang, Jia-Zhong

    2008-10-19

    Acidic persulfate oxidation is one of the most common procedures used to digest dissolved organic phosphorus compounds in water samples for total dissolved phosphorus determination. It has been reported that the rates of phosphoantimonylmolybdenum blue complex formation were significantly reduced in the digested sample matrix. This study revealed that the intermediate products of persulfate oxidation, not the slight change in pH, cause the slowdown of color formation. This effect can be remedied by adjusting digested samples pH to a near neural to decompose the intermediate products. No disturbing effects of chlorine on the phosphoantimonylmolybdenum blue formation in seawater were observed. It is noted that the modification of mixed reagent recipe cannot provide near neutral pH for the decomposition of the intermediate products of persulfate oxidation. This study provides experimental evidence not only to support the recommendation made in APHA standard methods that the pH of the digested sample must be adjusted to within a narrow range of sample, but also to improve the understanding of role of residue from persulfate decomposition on the subsequent phosphoantimonylmolybdenum blue formation.

  14. Gamma irradiation of 2-mercaptobenzothiazole aqueous solution in the presence of persulfate.

    PubMed

    Bao, Qiburi; Chen, Lujun; Tian, Jinping; Wang, Jianlong

    2016-08-01

    Recently, water treatment by ionizing radiation has gained increasing attention as a powerful technology for the destruction of refractory pollutants. 2-Mercaptobenzothiazole (MBT) is known as a widespread, toxic and poorly biodegradable pollutant. This paper studied the gamma irradiation of aqueous solutions of MBT. Moreover, the effect of the addition of persulfate (S2O8(2-)) on the radiolytic destruction of MBT was investigated. The main transformation products of the studied compound were detected and the sequence of occurrence of the products was described. The change of biodegradability of MBT solution was also observed. The main results obtained in this study indicated that gamma radiation was effective for removing MBT in aqueous solution. Persulfate addition, which induced the formation of reactive sulfate radicals (SO4(-)), greatly enhanced the degradation of MBT. Benzothiazole was identified as the first radiation product, followed by 2-hydroxybenzothiazole. Decomposition of MBT started with the oxidation of -SH groups to sulfate ions. Possible pathways for MBT decomposition by gamma irradiation were proposed. The BOD/COD ratios of MBT samples were increased after radiation, indicating the improvement of biodegradability and reduction of toxicity. PMID:27521957

  15. Assessing acute toxicity potential of persulfate ISCO treated water.

    PubMed

    Liang, Chenju; Wang, Chi-Wei

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Deniz Turan, M.; Soner Altundoğan, H.

    2014-09-01

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

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

    PubMed

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

    2013-10-15

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

  18. 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.

  19. Peroxone activated persulfate treatment of 1,4-dioxane in the presence of chlorinated solvent co-contaminants.

    PubMed

    Eberle, Dylan; Ball, Raymond; Boving, Thomas B

    2016-02-01

    1,4-dioxane is often found as a co-contaminant with chlorinated volatile organic compounds (VOCs) at solvent release sites such as landfills, solvent recycling facilities, or fire training areas. Historically, soil and groundwater samples were not routinely analyzed for 1,4-dioxane and therefore the number of known 1,4-dioxane sites is still increasing. Due to its co-occurrence with chlorinated compounds, remediation strategies are needed that simultaneously treat both 1,4-dioxane as well as chlorinated VOC co-contaminants. In this proof of concept laboratory study, the fate of 1,4-dioxane was examined during the targeted destruction of aqueous phase VOC, using a peroxone activated persulfate (PAP) chemical oxidation method. Bench-scale experiments were carried out to evaluate the treatability of 1,4-dioxane as both a single-contaminant 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. The oxidative destruction of 1,4-dioxane, TCE and 1,1,1-TCA in single-contaminant batch systems followed pseudo-first-order reaction kinetics and even at the most dilute oxidant concentration lasted for at least 13 days. 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. Oxidation rates were up to 87% slower in a mixture of these three compounds. Although additional tests are necessary, our data suggest that PAP oxidation of 1,4-dioxane might aid in the cleanup of VOC contaminated sites. PMID:26408980

  20. Peroxone activated persulfate treatment of 1,4-dioxane in the presence of chlorinated solvent co-contaminants.

    PubMed

    Eberle, Dylan; Ball, Raymond; Boving, Thomas B

    2016-02-01

    1,4-dioxane is often found as a co-contaminant with chlorinated volatile organic compounds (VOCs) at solvent release sites such as landfills, solvent recycling facilities, or fire training areas. Historically, soil and groundwater samples were not routinely analyzed for 1,4-dioxane and therefore the number of known 1,4-dioxane sites is still increasing. Due to its co-occurrence with chlorinated compounds, remediation strategies are needed that simultaneously treat both 1,4-dioxane as well as chlorinated VOC co-contaminants. In this proof of concept laboratory study, the fate of 1,4-dioxane was examined during the targeted destruction of aqueous phase VOC, using a peroxone activated persulfate (PAP) chemical oxidation method. Bench-scale experiments were carried out to evaluate the treatability of 1,4-dioxane as both a single-contaminant 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. The oxidative destruction of 1,4-dioxane, TCE and 1,1,1-TCA in single-contaminant batch systems followed pseudo-first-order reaction kinetics and even at the most dilute oxidant concentration lasted for at least 13 days. 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. Oxidation rates were up to 87% slower in a mixture of these three compounds. Although additional tests are necessary, our data suggest that PAP oxidation of 1,4-dioxane might aid in the cleanup of VOC contaminated sites.

  1. 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

  2. Effect and mechanism of persulfate activated by different methods for PAHs removal in soil

    EPA Science Inventory

    The influence of persulfate activation methods on polycyclic aromatic hydrocarbons (PAHs) degradation was investigated and included thermal, citrate chelated iron, and alkaline, and a hydrogen peroxide(H2O2)-persulfate binary mixture. Thermal activation (60◦C) resulted in t...

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

    PubMed

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

    2013-12-14

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

  4. 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

    ... Five-Year (``Sunset'') Review, 76 FR 13862 (March 1, 2013). Scope of the Order The products covered by the order are persulfates, including ammonium, potassium, and sodium persulfates. The chemical formula... . Potassium persulfates are currently classifiable under subheading 2833.40.10 of the Harmonized...

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

    PubMed

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

    2014-03-15

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

  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.

  7. 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. PMID:25944366

  8. Simultaneous removal of Cr(VI) and phenol by persulfate activated with bentonite-supported nanoscale zero-valent iron: Reactivity and mechanism.

    PubMed

    Diao, Zeng-Hui; Xu, Xiang-Rong; Chen, Hui; Jiang, Dan; Yang, Yu-Xi; Kong, Ling-Jun; Sun, Yu-Xin; Hu, Yong-Xia; Hao, Qin-Wei; Liu, Ling

    2016-10-01

    The applicability of bentonite-supported nanoscale zero-valent iron (B-nZVI) as a catalyst to activate persulfate (PS) for the simultaneous removal of Cr(VI) and phenol was systematically investigated in this study. Experimental results demonstrated that phenol degradation was significantly enhanced under acidic condition and with oxygen supply, whereas the Cr(VI) reduction was not obviously declined. The removal efficiencies of Cr(VI) and phenol in B-nZVI/PS combined system were 99.8 and 72.3%, respectively. Cr(VI) reduction and phenol oxidation was simultaneously achieved in B-nZVI/PS combined system, which provided a promising environmental treatment for industrial wastewater containing metal ions and organic compounds. An acidic condition was more favorable to the decomposition of persulfate for the production of sulfate radicals. Radical scavenging tests revealed that the predominant reactive oxygen species for phenol degradation was SO4(-), neither HO nor O2(-). A reaction mechanism, which involves the Cr(VI) removal mainly by the reduction of nZVI and the degradation of phenol mainly by the SO4(-) from the decomposition of persulfate, was proposed. These findings revealed that B-nZVI/PS combined system has a potential in the environmental remediation polluted jointly by organic compounds and/or heavy metals. PMID:27235826

  9. Simultaneous removal of Cr(VI) and phenol by persulfate activated with bentonite-supported nanoscale zero-valent iron: Reactivity and mechanism.

    PubMed

    Diao, Zeng-Hui; Xu, Xiang-Rong; Chen, Hui; Jiang, Dan; Yang, Yu-Xi; Kong, Ling-Jun; Sun, Yu-Xin; Hu, Yong-Xia; Hao, Qin-Wei; Liu, Ling

    2016-10-01

    The applicability of bentonite-supported nanoscale zero-valent iron (B-nZVI) as a catalyst to activate persulfate (PS) for the simultaneous removal of Cr(VI) and phenol was systematically investigated in this study. Experimental results demonstrated that phenol degradation was significantly enhanced under acidic condition and with oxygen supply, whereas the Cr(VI) reduction was not obviously declined. The removal efficiencies of Cr(VI) and phenol in B-nZVI/PS combined system were 99.8 and 72.3%, respectively. Cr(VI) reduction and phenol oxidation was simultaneously achieved in B-nZVI/PS combined system, which provided a promising environmental treatment for industrial wastewater containing metal ions and organic compounds. An acidic condition was more favorable to the decomposition of persulfate for the production of sulfate radicals. Radical scavenging tests revealed that the predominant reactive oxygen species for phenol degradation was SO4(-), neither HO nor O2(-). A reaction mechanism, which involves the Cr(VI) removal mainly by the reduction of nZVI and the degradation of phenol mainly by the SO4(-) from the decomposition of persulfate, was proposed. These findings revealed that B-nZVI/PS combined system has a potential in the environmental remediation polluted jointly by organic compounds and/or heavy metals.

  10. [Advanced Treatment of Effluent from Industrial Park Wastewater Treatment Plant by Ferrous Ion Activated Sodium Persulfate].

    PubMed

    Zhu, Song-mei; Zhou, Zhen; Gu, Ling-yun; Jiang, Hai-tao; Ren, Jia-min; Wang, Luo-chun

    2016-01-15

    Fe(II) activated sodium persulfate (PS) technology was used for advanced treatment of effluent from industrial park wastewater treatment plant. Separate and combined effects of PS/COD, Fe(II)/PS and pH on COD and TOC removal were analyzed by the response surface methodology. Variations of organic substances before and after Fe(II)-PS oxidation were characterized by UV-Vis spectrometry, gel chromatography and three-dimensional fluorescence. PS/COD and Fe(II)/PS had significant effect on COD removal, while all the three factors had significant effect on TOC removal. The combined effect of PS/COD and pH had significant effect on COD removal. COD and TOC removal efficiencies reached 50.7% and 60.6% under optimized conditions of PS/COD 3.47, Fe(II)/PS 3.32 and pH 6.5. Fe(II)-PS oxidation converted macromolecular organic substances to small ones, and reduced contents of protein-, humic- and fulvic-like substances.

  11. Sodium persulfate-assisted mechanochemical degradation of tetrabromobisphenol A: Efficacy, products and pathway.

    PubMed

    Liu, Xitao; Zhang, Xiaohui; Zhang, Kunlun; Qi, Chengdu

    2016-05-01

    In recent years, activated persulfate (PS) oxidation has been developed as a new advanced oxidation process for the degradation of organic pollutants. On the other hand, the mechanochemical method has exhibited a unique advantage in dealing with chemical wastes. The degradation of tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant (BFR), in wastes has attracted considerable attention. In this study, the efficacy of a CaO-mechanochemical (CaO-MC) treatment system assisted by the addition of PS for the degradation of TBBPA was investigated. Under the optimum reaction conditions with a mole ratio of PS:CaO = 1:4 and less than 12.5% of TBBPA by mass, the degradation and debromination of TBBPA were completed within 2 h, while the mineralization was completed within 4 h. Characterization of the milled sample by XRD revealed that CaSO4 crystallization occurred. The TG results illustrate that there was little organic matter left after 4 h of milling. Raman and FT-IR spectra exhibited the TBBPA destruction process and disappearance of the organic groups. Through analysis by LC/MS/MS, seventeen intermediates were identified. The mechanism of TBBPA degradation by the PS-assisted CaO-MC treatment system was explained from two aspects, the course of crystallization and the degradation of TBBPA by activated PS, and two parallel initiation pathways were proposed.

  12. Sodium persulfate-assisted mechanochemical degradation of tetrabromobisphenol A: Efficacy, products and pathway.

    PubMed

    Liu, Xitao; Zhang, Xiaohui; Zhang, Kunlun; Qi, Chengdu

    2016-05-01

    In recent years, activated persulfate (PS) oxidation has been developed as a new advanced oxidation process for the degradation of organic pollutants. On the other hand, the mechanochemical method has exhibited a unique advantage in dealing with chemical wastes. The degradation of tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant (BFR), in wastes has attracted considerable attention. In this study, the efficacy of a CaO-mechanochemical (CaO-MC) treatment system assisted by the addition of PS for the degradation of TBBPA was investigated. Under the optimum reaction conditions with a mole ratio of PS:CaO = 1:4 and less than 12.5% of TBBPA by mass, the degradation and debromination of TBBPA were completed within 2 h, while the mineralization was completed within 4 h. Characterization of the milled sample by XRD revealed that CaSO4 crystallization occurred. The TG results illustrate that there was little organic matter left after 4 h of milling. Raman and FT-IR spectra exhibited the TBBPA destruction process and disappearance of the organic groups. Through analysis by LC/MS/MS, seventeen intermediates were identified. The mechanism of TBBPA degradation by the PS-assisted CaO-MC treatment system was explained from two aspects, the course of crystallization and the degradation of TBBPA by activated PS, and two parallel initiation pathways were proposed. PMID:26359264

  13. 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.

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

    PubMed

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

    2015-11-01

    Granular activated carbon with silver loaded as activator (Ag/GAC) was prepared using impregnation method. N2 adsorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were adopted to characterize the Ag/GAC, showing that silver was successfully loaded on granular activated carbon. The oxidation degradation of acid orange 7 (AO7) by the Ag/GAC activated by persulfate (PS) was investigated at ambient temperature. The influences of factors such as Ag loading, PS or Ag/GAC dosages and initial pH on the degradation of AO7 were evaluated. The results demonstrated that the degradation rate of AO7 could reach more than 95.0% after 180 min when the Ag loading content, PS/AO7 molar ratio, the Ag/GAC dosage were 12.7 mg x g(-1), 120: 1, 1.0 g x L(-1), respectively. The initial pH had significant effect on the AO7 degradation, with pH 5.0 as the optimal pH for the degradation of AO7. The possible degradation pathway was proposed for the AO7 degradation by using UV-visible spectroscopy and gas chromatography-mass spectrometry (GG/MS). The azo bond and naphthalene ring in the AO7 were destroyed during the degradation, with phthalic acid and acetophenone as the main degradation products. PMID:26910999

  15. Mineralization of naphtenic acids with thermally-activated persulfate: The important role of oxygen.

    PubMed

    Xu, Xiyan; Pliego, Gema; Zazo, Juan A; Casas, Jose A; Rodriguez, Juan J

    2016-11-15

    This study reports on the mineralization of model naphtenic acids (NAs) in aqueous solution by catalyst-free thermally-activated persulfate (PS) oxidation. These species are found to be pollutants in oil sands process-affected waters. The NAs tested include saturated-ring (cyclohexanecarboxylic and cyclohexanebutyric acids) and aromatic (2-naphthoic and 1,2,3,4-tetrahydro-2-naphthoic acids) structures, at 50mgL(-1)starting concentration. The effect of PS dose within a wide range (10-100% of the theoretical stoichiometric) and working temperature (40-97°C) was investigated. At 80°C and intitial pH=8 complete mineralization of the four NAs was achieved with 40-60% of the stoichiometric PS dose. This is explained because of the important contribution of oxygen, which was experimentally verified and was found to be more effective toward the NAs with a single cyclohexane ring than for the bicyclic aromatic-ring-bearing ones. The effect of chloride and bicarbonate was also checked. The former showed negative effect on the degradation rate of NAs whereas it was negligible or even positive for bicarbonate. The rate of mineralization was well described by simple pseudo-first order kinetics with values of the rate constants normalized to the PS dose within the range of 0.062-0.099h(-1). Apparent activation energy values between 93.7-105.3kJmol(-1) were obtained. PMID:27442986

  16. Activated carbon fiber for heterogeneous activation of persulfate: implication for the decolorization of azo dye.

    PubMed

    Chen, Jiabin; Hong, Wei; Huang, Tianyin; Zhang, Liming; Li, Wenwei; Wang, Ying

    2016-09-01

    Activated carbon fiber (ACF) was used as a green catalyst to activate persulfate (PS) for oxidative decolorization of azo dye. ACF demonstrated a higher activity than activated carbon (AC) to activate PS to decolorize Orange G (OG). The decolorization efficiency of OG increased as ACF loading, PS dosage, and temperature increased. OG decolorization followed a pseudo first-order kinetics, and the activation energy was 40.902 kJ/mol. pH had no apparent effect on OG decolorization. Radical quenching experiments with various radical scavengers (e.g., alcohols, phenol) showed that radical-induced decolorization of OG took place on the surface of ACF, and both SO4 (·-) and HO· were responsible for OG decolorization. The impact of inorganic salts was also evaluated because they are important compositions of dye wastewater. Cl(-) and SO4 (2-) exhibited a promoting effect on OG decolorization, and the accelerating rate increased with elevating dosage of ions. Addition of Cl(-) and SO4 (2-) could increase the adsorption of OG on ACF surface, thus favorable for OG decolorization caused by the surface-bound SO4 (·-) and HO·. Conversely, HCO3 (-) and humic acid (HA) slightly inhibited OG decolorization. The azo band and naphthalene ring on OG were remarkably destructed to other intermediates and finally mineralized to CO2 and H2O. PMID:27294702

  17. Disinfection of ballast water with iron activated persulfate.

    PubMed

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

    2013-10-15

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

  18. 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

  19. 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 (Fe3+, Cu2+, Ni2+, and Zn2+) 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 λ (λ=[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.

  20. 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

    ... Agreements Act, H. Doc. No. 103-316, Vol. 1, at 870 (1994). Because United Initiators did not respond to the... Republic of China, 62 FR 36259 (July 7, 1997) (``Persulfates Order and Amended Final''), amended by Notice of Amended Antidumping Duty Order: Persulfates From the People's Republic of China, 62 FR 39212...

  1. Degradation of trimethoprim by gamma irradiation in the presence of persulfate

    NASA Astrophysics Data System (ADS)

    Zhang, Zhonglei; Yang, Qi; Wang, Jianlong

    2016-10-01

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

  2. 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.

  3. 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.

  4. 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.

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

    PubMed

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

    2016-04-01

    Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from -3.4±0.3 to -4.3±0.3‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from -7.0±0.4 to -13.6±1.2‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO4(-)). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO).

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

    PubMed

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

    2016-04-01

    Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from -3.4±0.3 to -4.3±0.3‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from -7.0±0.4 to -13.6±1.2‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO4(-)). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). PMID:26784392

  7. Achieving synergy between chemical oxidation and stabilization in a contaminated soil.

    PubMed

    Srivastava, Vipul J; Hudson, Jeffrey Michael; Cassidy, Daniel P

    2016-07-01

    Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies. PMID:27088536

  8. 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.

  9. 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…

  10. Chemisorption of Perfluorooctanoic Acid on Powdered Activated Carbon Initiated by Persulfate in Aqueous Solution.

    PubMed

    Sun, Bo; Ma, Jun; Sedlak, David L

    2016-07-19

    Perfluorooctanoic acid (PFOA) is a perfluorocarboxylic acid that is difficult to treat by most conventional methods. As a result, it is often removed from solution by adsorption on powdered activated carbon (PAC), followed by incineration of the spent carbon. To provide a new approach for treatment, PFOA was exposed to sulfate radicals (SO4(-•)) produced by thermolysis of persulfate (S2O8(2-)) in the presence of PAC. Under acidic conditions, thermal activation of persulfate resulted in transformation of PFOA to shorter-chain-length perfluorinated compounds, as previously reported. However, when thermolysis of persulfate occurred under circumneutral pH conditions in the presence of PAC, a new removal pathway for PFOA was observed. Under these conditions, the removal of PFOA was attributable to chemisorption, a process in which PAC catalyzed persulfate decomposition and reacted with the transformation products to produce covalently bound PFOA. At PAC concentrations between 200 and 1000 mg/L and an initial PFOA concentration of 0.5 μM, covalent bonding resulted in removal of 10-40% of the PFOA. Under these conditions, the process resulted in removal of more than half of a more hydrophilic perfluoroalkyl acid (i.e., perfluorobutanoic acid, PFBA), which was greater than the amount of PFBA removed by physical adsorption on PAC. Although the high reaction temperatures (i.e., 80 °C) and relatively high doses of PAC used in this study may be impractical for drinking water treatment, this process may be applied to the treatment of these recalcitrant compounds in industrial wastewater, reverse osmosis concentrate, and other waters that contain high concentrations of PFOA and other perfluorocarboxylic acids. PMID:27336204

  11. Development of crosslinked methylcellulose hydrogels for soft tissue augmentation using an ammonium persulfate-ascorbic acid redox system.

    PubMed

    Gold, Gittel T; Varma, Devika M; Taub, Peter J; Nicoll, Steven B

    2015-12-10

    Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers.

  12. Development of crosslinked methylcellulose hydrogels for soft tissue augmentation using an ammonium persulfate-ascorbic acid redox system.

    PubMed

    Gold, Gittel T; Varma, Devika M; Taub, Peter J; Nicoll, Steven B

    2015-12-10

    Hydrogels composed of methylcellulose are candidate materials for soft tissue reconstruction. Although photocrosslinked methylcellulose hydrogels have shown promise for such applications, gels crosslinked using reduction-oxidation (redox) initiators may be more clinically viable. In this study, methylcellulose modified with functional methacrylate groups was polymerized using an ammonium persulfate (APS)-ascorbic acid (AA) redox initiation system to produce injectable hydrogels with tunable properties. By varying macromer concentration from 2% to 4% (w/v), the equilibrium moduli of the hydrogels ranged from 1.47 ± 0.33 to 5.31 ± 0.71 kPa, on par with human adipose tissue. Gelation time was found to conform to the ISO standard for injectable materials. Cellulase treatment resulted in complete degradation of the hydrogels within 24h, providing a reversible corrective feature. Co-culture with human dermal fibroblasts confirmed the cytocompatibility of the gels based on DNA measurements and Live/Dead imaging. Taken together, this evidence indicates that APS-AA redox-polymerized methylcellulose hydrogels possess properties beneficial for use as soft tissue fillers. PMID:26428151

  13. Efficient transformation of DDTs with Persulfate Activation by Zero-valent Iron Nanoparticles: A Mechanistic Study.

    PubMed

    Zhu, Changyin; Fang, Guodong; Dionysiou, Dionysios D; Liu, Cun; Gao, Juan; Qin, Wenxiu; Zhou, Dongmei

    2016-10-01

    In this study, persulfate (PS) activation by nano-Fe(0) was used to degrade dichlorodiphenyltrichloroethane (DDT), and the mechanism of this process was elucidated with EPR, GC-MS and free-radical quenching studies. It was found that DDT was degraded efficiently in PS/nano-Fe(0), and GC-MS analysis showed that benzoic acid, benzyl alcohol, dichlorobenzophenone and 2,2-bis(p-chlorophenyl)-ethane were the dominant products of DDT degradation, while only dechlorination products (DDD and DDE) were observed in nano-Fe(0) without persulfate. EPR results showed that persulfate activation by nano-Fe(0) led to the production of more sulfate radicals and hydroxyl radicals, which accounted for DDT degradation. But the free radical quenching studies suggested that the addition of ethanol to PS/nano-Fe(0) favored the reductive dechlorination of DDT, which was ascribed that the formed ethanol radical (CH(CH3)OH) enhanced the reductive dechlorination of DDT. Furthermore, the nano-Fe(0) loading not only affected the degradation efficiency of DDT, but also influenced the intermediate product distribution of DDT degradation in the PS/nano-Fe(0) process. PMID:27236432

  14. 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.

  15. Degradation of trichloroethene by siderite-catalyzed hydrogen peroxide and persulfate: Investigation of reaction mechanisms and degradation products

    PubMed Central

    Yan, Ni; Liu, Fei; Xue, Qiang; Brusseau, Mark L.; Liu, Yali; Wang, Junjie

    2015-01-01

    A binary catalytic system, siderite-catalyzed hydrogen peroxide (H2O2) coupled with persulfate (S2O82−), was investigated for the remediation of trichloroethene (TCE) contamination. Batch experiments were conducted to investigate reaction mechanisms, oxidant decomposition rates, and degradation products. By using high performance liquid chromatography (HPLC) coupled with electron paramagnetic resonance (EPR), we identified four radicals (hydroxyl (HO·), sulfate (SO4−·), hydroperoxyl (HO2·), and superoxide (O2−·)) in the siderite-catalyzed H2O2-S2O82− system. In the absence of S2O82− (i.e., siderite-catalyzed H2O2), a majority of H2O2 was decomposed in the first hour of the experiment, resulting in the waste of HO·. The addition of S2O82− moderated the H2O2 decomposition rate, producing a more sustainable release of hydroxyl radicals that improved the treatment efficiency. Furthermore, the heat released by H2O2 decomposition accelerated the activation of S2O82−, and the resultant SO4−· was the primary oxidative agent during the first two hours of the reaction. Dichloroacetic acid was firstly detected by ion chromatography (IC). The results of this study indicate a new insight to the reaction mechanism for the catalytic binary H2O2-S2O82− oxidant system, and the delineation of radicals and the discovery of the chlorinated byproduct provide useful information for efficient treatment of chlorinated-solvent contamination in groundwater. PMID:26236152

  16. Effect of benzoic acid on the removal of 1,2-dichloroethane by a siderite-catalyzed hydrogen peroxide and persulfate system.

    PubMed

    Li, Shengpin; Li, Mengjiao; Luo, Ximing; Huang, Guoxin; Liu, Fei; Chen, Honghan

    2016-01-01

    Benzoic acid can affect the iron-oxide mineral dissolution and react with hydroxyl radical. This study investigated its effect on 1,2-dichloroethane removal process by siderite-catalyzed hydrogen peroxide and persulfate. The variation of benzoic acid concentrations can affect pH value and soluble iron concentrations; when benzoic acid varied from 0 to 0.5 mmol/L, pH increased while Fe(2+) and Fe(3+) concentrations decreased, resulting in 1,2-dichloroethane removal efficiency which decreased from 91.2 to 5.0%. However, when benzoic acid varied from 0.5 to 10 mmol/L, pH decreased while Fe(2+) and Fe(3+) concentrations increased, resulting in 1,2-dichloroethane removal efficiency which increased from 5.0 to 83.4%.

  17. Core-shell Fe3O4@MIL-101(Fe) composites as heterogeneous catalysts of persulfate activation for the removal of Acid Orange 7.

    PubMed

    Yue, Xinxin; Guo, Weilin; Li, Xianghui; Zhou, Haihong; Wang, Ruiqin

    2016-08-01

    In this study, a novel core-shell Fe3O4@MIL-101 (MIL stands for Materials of Institute Lavoisier) composite was successfully synthesized by hydrothermal method and was fully characterized by X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectra, and X-ray photoelectron spectroscopy. The composite was introduced as a catalyst to generate powerful radicals from persulfate for the removal of Acid Orange 7 in an aqueous solution. Effects of the central metal ions of MIL-101, amino group content of MIL-101, and pH were evaluated in batch experiments. It was found that both hydroxyl and sulfate radicals were generated; importantly, sulfate radicals were speculated to serve as the dominant active species in the catalytic oxidation of Acid Orange 7. In addition, a possible mechanism was proposed. This study provides new physical insights for the rational design of advanced metal-organic frameworks (MOF)-based catalysts for improved environmental remediation. PMID:27098883

  18. Heat-activated liposome targeting to streptavidin-coated surfaces.

    PubMed

    Jing, Yujia; Trefná, Hana Dobšíček; Persson, Mikael; Svedhem, Sofia

    2015-06-01

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

  19. 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.

  20. Metal-free catalysis of persulfate activation and organic-pollutant degradation by nitrogen-doped graphene and aminated graphene.

    PubMed

    Chen, Hao; Carroll, Kenneth C

    2016-08-01

    We evaluated three types of functionalized, graphene-based materials for activating persulfate (PS) and removing (i.e., sorption and oxidation) sulfamethoxazole (SMX) as a model emerging contaminant. Although advanced oxidative water treatment requires PS activation, activation requires energy or chemical inputs, and toxic substances are contained in many catalysts. Graphene-based materials were examined herein as an alternative to metal-based catalysts. Results show that nitrogen-doped graphene (N-GP) and aminated graphene (NH2-GP) can effectively activate PS. Overall, PS activation by graphene oxide was not observed in this study. N-GP (50 mg L(-1)) can rapidly activate PS (1 mM) to remove >99.9% SMX within 3 h, and NH2-GP (50 mg L(-1)) activated PS (1 mM) can also remove 50% SMX within 10 h. SMX sorption and total removal was greater for N-GP, which suggests oxidation was enhanced by increasing proximity to PS activation sites. Increasing pH enhanced the N-GP catalytic ability, and >99.9% SMX removal time decreased from 3 h to 1 h when pH increased from 3 to 9. However, the PS catalytic ability was inhibited at pH 9 for NH2-GP. Increases in ionic strength (100 mM NaCl or Na2SO4) and addition of radical scavengers (500 mM ethanol) both had negligible impacts on SMX removal. With bicarbonate addition (100 mM), while the catalytic ability of N-GP remained unaltered, NH2-GP catalytic ability was inhibited completely. Humic acid (250 mg L(-1)) was partially effective in inhibiting SMX removal in both N-GP and NH2-GP systems. These results have implications for elucidating oxidant catalysis mechanisms, and they quantify the ability of functionalization of graphene with hetero-atom doping to effectively catalyze PS for water treatment of organic pollutants including emerging contaminants. PMID:27179328

  1. 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

  2. 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 Persulfates From China; Notice of Commission Determination To Conduct a Full Five-Year Review... further information concerning the conduct of this review and rules of general application, consult the... response to its notice of institution (78 FR 13891, March 1, 2013) was adequate and that the...

  3. Comparative evaluation of iodoacids removal by UV/persulfate and UV/H2O2 processes.

    PubMed

    Xiao, Yongjun; Zhang, Lifeng; Zhang, Wei; Lim, Kok-Yong; Webster, Richard D; Lim, Teik-Thye

    2016-10-01

    To develop a cost-effective method for post-formation mitigation of iodinated disinfection by-products, degradation of iodoacids by UV, UV/PS (persulfate), and UV/H2O2 was extensively investigated in this study. UV direct photolysis of 4 iodoacids followed first-order kinetics with rate constants in the range of 2.43 × 10(-4)-3.02 × 10(-3) cm(2) kJ(-1). The derived quantum yields (Ф254) of the 4 iodoacids range from 0.13 to 0.34, respectively. A quantitative structure-activity relationship (QSAR) model was subsequently established and applied to predict the direct photolysis rates of 6 other structurally similar iodoacids whose standards are commercially unavailable. At a UV dose of 140 mJ cm(-2) which is typically applied for disinfection of drinking water, the removal percentages of 4 iodoacids were only between 3.35% and 34.7%. Thus, ICH2CO2H (IAA), the most photo-recalcitrant species, was selected as the target compound for removal in the UV/PS and UV/H2O2 processes. The IAA degradation rates decreased with increasing pH from 3 to 11 in both processes. Humic acid (HA) and HCO3(-) had inhibitory effects on IAA degradation in both processes. Cl(-) adversely affected the IAA degradation in the UV/PS process but had no effect in the UV/H2O2 process. Generally, in the deionized (DI) water, surface water, treated drinking water, and secondary effluent, UV/PS process is more effective than UV/H2O2 process for IAA removal, based on the same molar ratio of oxidant: IAA. SO4(-) generated in the UV/PS process yields a greater mineralization of IAA than HO in the UV/H2O2 process. IO3(-) was the predominant end-product in the UV/PS process, while I(-) was the major end-product in the UV/H2O2 process. The respective contributions of UV, HO, and SO4(-) for IAA removal in the UV/PS process were 7.8%, 14.7%, and 77.5%, respectively, at a specific condition (1.5 μM IAA, 60 μM oxidant, and pH 7). Compared to UV/H2O2 process, UV/PS was also observed as more cost

  4. Comparative evaluation of iodoacids removal by UV/persulfate and UV/H2O2 processes.

    PubMed

    Xiao, Yongjun; Zhang, Lifeng; Zhang, Wei; Lim, Kok-Yong; Webster, Richard D; Lim, Teik-Thye

    2016-10-01

    To develop a cost-effective method for post-formation mitigation of iodinated disinfection by-products, degradation of iodoacids by UV, UV/PS (persulfate), and UV/H2O2 was extensively investigated in this study. UV direct photolysis of 4 iodoacids followed first-order kinetics with rate constants in the range of 2.43 × 10(-4)-3.02 × 10(-3) cm(2) kJ(-1). The derived quantum yields (Ф254) of the 4 iodoacids range from 0.13 to 0.34, respectively. A quantitative structure-activity relationship (QSAR) model was subsequently established and applied to predict the direct photolysis rates of 6 other structurally similar iodoacids whose standards are commercially unavailable. At a UV dose of 140 mJ cm(-2) which is typically applied for disinfection of drinking water, the removal percentages of 4 iodoacids were only between 3.35% and 34.7%. Thus, ICH2CO2H (IAA), the most photo-recalcitrant species, was selected as the target compound for removal in the UV/PS and UV/H2O2 processes. The IAA degradation rates decreased with increasing pH from 3 to 11 in both processes. Humic acid (HA) and HCO3(-) had inhibitory effects on IAA degradation in both processes. Cl(-) adversely affected the IAA degradation in the UV/PS process but had no effect in the UV/H2O2 process. Generally, in the deionized (DI) water, surface water, treated drinking water, and secondary effluent, UV/PS process is more effective than UV/H2O2 process for IAA removal, based on the same molar ratio of oxidant: IAA. SO4(-) generated in the UV/PS process yields a greater mineralization of IAA than HO in the UV/H2O2 process. IO3(-) was the predominant end-product in the UV/PS process, while I(-) was the major end-product in the UV/H2O2 process. The respective contributions of UV, HO, and SO4(-) for IAA removal in the UV/PS process were 7.8%, 14.7%, and 77.5%, respectively, at a specific condition (1.5 μM IAA, 60 μM oxidant, and pH 7). Compared to UV/H2O2 process, UV/PS was also observed as more cost

  5. Perfluorooctanoic Acid Degradation Using UV-Persulfate Process: Modeling of the Degradation and Chlorate Formation.

    PubMed

    Qian, Yajie; Guo, Xin; Zhang, Yalei; Peng, Yue; Sun, Peizhe; Huang, Ching-Hua; Niu, Junfeng; Zhou, Xuefei; Crittenden, John C

    2016-01-19

    In this study, we investigated the destruction and by-product formation of perfluorooctanoic acid (PFOA) using ultraviolet light and persulfate (UV-PS). Additionally, we developed a first-principles kinetic model to simulate both PFOA destruction and by-product and chlorate (ClO3(-)) formation in ultrapure water (UW), surface water (SW), and wastewater (WW). PFOA degradation was significantly suppressed in the presence of chloride and carbonate species and did not occur until all the chloride was converted to ClO3(-) in UW and for low DOC concentrations in SW. The model was able to simulate the PS decay, pH changes, radical concentrations, and ClO3(-) formation for UW and SW. However, our model was unable to simulate PFOA degradation well in WW, possibly from PS activation by NOM, which in turn produced sulfate radicals. PMID:26686982

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

    PubMed

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

    2013-11-01

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

  7. 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

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

    PubMed

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

    2015-10-30

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

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

    PubMed

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

    2015-10-30

    Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. PMID:26093352

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

    PubMed

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

    2011-04-01

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

  11. Heat-activated Plasmonic Chemical Sensors for Harsh Environments

    SciTech Connect

    Carpenter, Michael; Oh, Sang-Hyun

    2015-12-01

    A passive plasmonics based chemical sensing system to be used in harsh operating environments was investigated and developed within this program. The initial proposed technology was based on combining technologies developed at the SUNY Polytechnic Institute Colleges of Nanoscale Science and Engineering (CNSE) and at the University of Minnesota (UM). Specifically, a passive wireless technique developed at UM was to utilize a heat-activated plasmonic design to passively harvest the thermal energy from within a combustion emission stream and convert this into a narrowly focused light source. This plasmonic device was based on a bullseye design patterned into a gold film using focused ion beam methods (FIB). Critical to the design was the use of thermal stabilizing under and overlayers surrounding the gold film. These stabilizing layers were based on both atomic layer deposited films as well as metal laminate layers developed by United Technologies Aerospace Systems (UTAS). While the bullseye design was never able to be thermally stabilized for operating temperatures of 500oC or higher, an alternative energy harvesting design was developed by CNSE within this program. With this new development, plasmonic sensing results are presented where thermal energy is harvested using lithographically patterned Au nanorods, replacing the need for an external incident light source. Gas sensing results using the harvested thermal energy are in good agreement with sensing experiments, which used an external incident light source. Principal Component Analysis (PCA) was used to reduce the wavelength parameter space from 665 variables down to 4 variables with similar levels of demonstrated selectivity. The method was further improved by patterning rods which harvested energy in the near infrared, which led to a factor of 10 decrease in data acquisition times as well as demonstrated selectivity with a reduced wavelength data set. The combination of a plasmonic-based energy harvesting

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

    PubMed

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

    2016-01-01

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

  13. Kinetics and mechanism investigation on the destruction of oxytetracycline by UV-254nm activation of persulfate.

    PubMed

    Liu, Yiqing; He, Xuexiang; Fu, Yongsheng; Dionysiou, Dionysios D

    2016-03-15

    Oxytetracycline (OTC), an important broad-spectrum antibiotic, has been detected extensively in various environmental systems, which may have a detrimental impact on ecosystem and human health through the development of drug resistant bacteria and pathogens. In this study, the degradation of OTC was evaluated by UV-254nm activated persulfate (PS). The observed UV fluence based pseudo first-order rate constant (kobs) was found to be the highest at near neutral pH conditions (pH 5.5-8.5). Presence of various natural water constituents had different effects on OTC degradation, with a significant enhancement in the presence of bicarbonate or Cu(2+). Limited elimination of total organic carbon (TOC) and PS was observed during the mineralization of OTC. Transformation byproducts in the presence and absence of hydroxyl radical scavenging agent tert-butanol (t-BuOH) were identified using ultra-high definition accurate-mass quadrupole time-of-flight liquid chromatography/mass spectrometer (LC-QTOF/MS). Potential OTC degradation mechanism was subsequently proposed revealing four different reaction pathways by SO4(-) reaction including hydroxylation (+16Da), demethylation (-14Da), decarbonylation (-28Da) and dehydration (-18Da). This study suggests that UV-254nm/PS is a promising treatment technology for the control of water pollution caused by emerging contaminants such as OTC.

  14. 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

  15. Degradation of flumequine in aqueous solution by persulfate activated with common methods and polyhydroquinone-coated magnetite/multi-walled carbon nanotubes catalysts.

    PubMed

    Feng, Mingbao; Qu, Ruijuan; Zhang, Xiaoling; Sun, Ping; Sui, Yunxia; Wang, Liansheng; Wang, Zunyao

    2015-11-15

    In recent years, flumequine (FLU) has been ubiquitously detected in surface waters and municipal wastewaters. In light of its potential negative impacts to aquatic species, growing concern has been arisen for the removal of this antibiotic from natural waters. In this study, the kinetics, degradation mechanisms and pathways of aqueous FLU by persulfate (PS) oxidation were systematically determined. Three common activation methods, including heat, Fe(2+) and Cu(2+), and a novel heterogeneous catalyst, namely, polyhydroquinone-coated magnetite/multi-walled carbon nanotubes (Fe3O4/MWCNTs/PHQ), were investigated to activate PS for FLU removal. It was found that these three common activators enhanced FLU degradation obviously, while several influencing factors, such as solution pH, inorganic ions (especially HCO3(-) at 5 mmol/L) and dissolved organic matter extracts, exerted their different effects on FLU removal. The catalysts were characterized, and an efficient catalytic degradation performance, high stability and excellent reusability were observed. The measured total organic carbon levels suggested that FLU can be effectively mineralized by using the catalysts. Radical mechanism was studied by combination of the quenching tests and electron paramagnetic resonance analysis. It was assumed that sulfate radicals predominated in the activation of PS with Fe3O4/MWCNTs/PHQ for FLU removal, while hydroxyl radicals also contributed to the catalytic oxidation process. In addition, a total of fifteen reaction intermediates of FLU were identified, from which two possible pathways were proposed involving hydroxylation, decarbonylation and ring opening. Overall, this study represented a systematical evaluation regarding the transformation process of FLU by PS, and showed that the heterogeneous catalysts can efficiently activate PS for FLU removal from the water environment.

  16. 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.

  17. A heat-activated and thermoresistant telomerase activity in Leishmania major Friedlin.

    PubMed

    Galindo, Maria Mercedes; Rodriguez, Evelyn; Rojas, Maria Gabriela; Figarella, Katherine; Campelo, Riward; Ramírez, Jose Luis

    2009-07-01

    Here we studied the telomerase activity of the human parasite Leishmania major. In this organism we have detected a high activity of this enzyme once several parameters such as heat activation, sequence of extension primer, and protein concentration are adjusted. The activity was not only heat activated, but also very resistant to heat denaturation. We believe L. major telomerase is an important activity and it may provide an adequate drug therapy target. PMID:19426669

  18. Fate of iron and polycyclic aromatic hydrocarbons during the remediation of a contaminated soil using iron-activated persulfate: A column study.

    PubMed

    Pardo, F; Santos, A; Romero, A

    2016-10-01

    Remediation of contaminated soils under flow-through conditions is an issue of great interest since it provides a better approach to real case applications than batch experiments. In this work, a column filled with soil, artificially spiked and aged for three months with Phenanthrene (PHE), Anthracene (ANT), Pyrene (PYR) and Benzo(a)pyrene (BaP), was treated for 25days with persulfate (PS) activated by Fe(3+) and nanoparticles of zerovalent iron (nZVI). Effects of type of iron fed into the column (Fe(3+) or nZVI) and nZVI concentration were studied. PS inlet concentration was 0.2mmolcm(-3) and residence time in the column was close to 1.72days. Iron, PS and polycyclic aromatic hydrocarbons (PAHs) concentration, as well as pH, were monitored during treatment. Concentration profiles of iron and PAHs were observed along the column, with higher iron concentrations and higher PAHs removal efficiencies in the closest sections to the column entrance. BaP and ANT were completely depleted regardless the conditions used, but PHE and PYR showed higher resistance to oxidation, achieving near a 90% removal in the closest sections to the injection source in all runs, but decreasing significantly with column length. Besides, natural degradation of ANT resulted in the formation 9.10-anthraquinone (ATQ), an oxy-PAH which showed higher resistance than PHE and PYR. Although higher PAHs removal efficiencies were achieved when nZVI was used as activator, only a moderate improvement was noticed when the highest concentration of nZVI was used as a consequence of radical scavenging by an excess of Fe(2+). Finally, a kinetic model based on runs performed in batch, from a previous work, was able to predict the experimental average concentrations of PAHs in the column when Fe(3+) was used as activator.

  19. Fate of iron and polycyclic aromatic hydrocarbons during the remediation of a contaminated soil using iron-activated persulfate: A column study.

    PubMed

    Pardo, F; Santos, A; Romero, A

    2016-10-01

    Remediation of contaminated soils under flow-through conditions is an issue of great interest since it provides a better approach to real case applications than batch experiments. In this work, a column filled with soil, artificially spiked and aged for three months with Phenanthrene (PHE), Anthracene (ANT), Pyrene (PYR) and Benzo(a)pyrene (BaP), was treated for 25days with persulfate (PS) activated by Fe(3+) and nanoparticles of zerovalent iron (nZVI). Effects of type of iron fed into the column (Fe(3+) or nZVI) and nZVI concentration were studied. PS inlet concentration was 0.2mmolcm(-3) and residence time in the column was close to 1.72days. Iron, PS and polycyclic aromatic hydrocarbons (PAHs) concentration, as well as pH, were monitored during treatment. Concentration profiles of iron and PAHs were observed along the column, with higher iron concentrations and higher PAHs removal efficiencies in the closest sections to the column entrance. BaP and ANT were completely depleted regardless the conditions used, but PHE and PYR showed higher resistance to oxidation, achieving near a 90% removal in the closest sections to the injection source in all runs, but decreasing significantly with column length. Besides, natural degradation of ANT resulted in the formation 9.10-anthraquinone (ATQ), an oxy-PAH which showed higher resistance than PHE and PYR. Although higher PAHs removal efficiencies were achieved when nZVI was used as activator, only a moderate improvement was noticed when the highest concentration of nZVI was used as a consequence of radical scavenging by an excess of Fe(2+). Finally, a kinetic model based on runs performed in batch, from a previous work, was able to predict the experimental average concentrations of PAHs in the column when Fe(3+) was used as activator. PMID:27235898

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. 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 μg/L, respectively. The LOQs determined for these analytes were 3.4 and 4.2 μg/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 μg/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.

  6. 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 μg/L, respectively. The LOQs determined for these analytes were 3.4 and 4.2 μg/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 μg/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

  7. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    NASA Astrophysics Data System (ADS)

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, Kewei; Lai, Ren

    2015-09-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery.

  8. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1.

    PubMed

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-09-30

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery.

  9. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1.

    PubMed

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx-TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

  10. A pain-inducing centipede toxin targets the heat activation machinery of nociceptor TRPV1

    PubMed Central

    Yang, Shilong; Yang, Fan; Wei, Ningning; Hong, Jing; Li, Bowen; Luo, Lei; Rong, Mingqiang; Yarov-Yarovoy, Vladimir; Zheng, Jie; Wang, KeWei; Lai, Ren

    2015-01-01

    The capsaicin receptor TRPV1 ion channel is a polymodal nociceptor that responds to heat with exquisite sensitivity through an unknown mechanism. Here we report the identification of a novel toxin, RhTx, from the venom of the Chinese red-headed centipede that potently activates TRPV1 to produce excruciating pain. RhTx is a 27-amino-acid small peptide that forms a compact polarized molecule with very rapid binding kinetics and high affinity for TRPV1. We show that RhTx targets the channel's heat activation machinery to cause powerful heat activation at body temperature. The RhTx–TRPV1 interaction is mediated by the toxin's highly charged C terminus, which associates tightly to the charge-rich outer pore region of the channel where it can directly interact with the pore helix and turret. These findings demonstrate that RhTx binding to the outer pore can induce TRPV1 heat activation, therefore providing crucial new structural information on the heat activation machinery. PMID:26420335

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

    PubMed

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

    2014-02-18

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

  12. Compatibility of polymers and chemical oxidants for enhanced groundwater remediation.

    PubMed

    Smith, Megan M; Silva, Jeff A K; Munakata-Marr, Junko; McCray, John E

    2008-12-15

    Polymer floods provide a promising method to more effectively deliver conventional groundwater treatment agents to organic contaminants distributed within heterogeneous aquifer systems. Combinations of nontoxic polymers (xanthan and hydrolyzed polyacrylamide) and common chemical oxidants (potassium permanganate and sodium persulfate) were investigated to determine the suitability of these mixtures for polymer-enhanced in situ chemical oxidation applications. Oxidant demand and solution viscosity were utilized as initial measures of chemical compatibility. After 72 h of reaction with both test oxidants, solution viscosities in mixtures containing hydrolyzed polyacrylamide were decreased by more than 90% (final viscosities approximately 2 cP), similar to the 95% viscosity loss (final viscosities approximately 1 cP, near that of water) observed in xanthan/persulfate experiments. In contrast, xanthan solutions exposed to potassium permanganate preserved 60-95% of initial viscosity after 72 h. Permanganate depletion in xanthan-containing experiments ranged from 2% to 24% over the same test period. Although oxidant consumption in xanthan/permanganate solutions appeared to be correlated with increasing xanthan concentrations, solutions of up to 2000 mg/L xanthan did not inhibit permanganate from oxidizing a dissolved-phase test contaminant (tetrachloroethene, PCE) in xanthan solution. These advantageous characteristics (high viscosity retention, moderate oxidant demand, and lack of competitive effects on PCE oxidation rate) render xanthan/permanganate the most compatible polymer/oxidant combination of those tested for remediation by polymer-enhanced chemical oxidation. PMID:19174907

  13. Compatibility of polymers and chemical oxidants for enhanced groundwater remediation.

    PubMed

    Smith, Megan M; Silva, Jeff A K; Munakata-Marr, Junko; McCray, John E

    2008-12-15

    Polymer floods provide a promising method to more effectively deliver conventional groundwater treatment agents to organic contaminants distributed within heterogeneous aquifer systems. Combinations of nontoxic polymers (xanthan and hydrolyzed polyacrylamide) and common chemical oxidants (potassium permanganate and sodium persulfate) were investigated to determine the suitability of these mixtures for polymer-enhanced in situ chemical oxidation applications. Oxidant demand and solution viscosity were utilized as initial measures of chemical compatibility. After 72 h of reaction with both test oxidants, solution viscosities in mixtures containing hydrolyzed polyacrylamide were decreased by more than 90% (final viscosities approximately 2 cP), similar to the 95% viscosity loss (final viscosities approximately 1 cP, near that of water) observed in xanthan/persulfate experiments. In contrast, xanthan solutions exposed to potassium permanganate preserved 60-95% of initial viscosity after 72 h. Permanganate depletion in xanthan-containing experiments ranged from 2% to 24% over the same test period. Although oxidant consumption in xanthan/permanganate solutions appeared to be correlated with increasing xanthan concentrations, solutions of up to 2000 mg/L xanthan did not inhibit permanganate from oxidizing a dissolved-phase test contaminant (tetrachloroethene, PCE) in xanthan solution. These advantageous characteristics (high viscosity retention, moderate oxidant demand, and lack of competitive effects on PCE oxidation rate) render xanthan/permanganate the most compatible polymer/oxidant combination of those tested for remediation by polymer-enhanced chemical oxidation.

  14. 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

  15. Degradation of methyl orange by ozone in the presence of ferrous and persulfate ions in a rotating packed bed.

    PubMed

    Ge, Deming; Zeng, Zequan; Arowo, Moses; Zou, Haikui; Chen, Jianfeng; Shao, Lei

    2016-03-01

    This work investigated the degradation of methyl orange by ozone in the presence of ferrous and persulfate ions (O3/Fe(2+)/S2O8(2-)) in a rotating packed bed. The effects of various operating parameters such as initial pH, rotational speed, gas-liquid ratio, ozone inlet concentration and reaction temperature on the degradation rate of methyl orange were studied with an aim to optimize the operation conditions. Results reveal that the degradation rate increased with an increase in rotational speed, gas-liquid ratio and ozone inlet concentration, and reached a maximum at 25 °C and initial pH 4. Contrast experiments involving ozone and ferrous ions (O3/Fe(2+)) were also carried out, and the results show approximately 10% higher degradation rate and COD removal in the O3/Fe(2+)/S2O8(2-) process than in the O3/Fe(2+) process. Additionally, the intermediates of the degradation process were analyzed to ascertain the degradation products.

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

    PubMed Central

    2014-01-01

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

  17. Degradation of methyl orange by ozone in the presence of ferrous and persulfate ions in a rotating packed bed.

    PubMed

    Ge, Deming; Zeng, Zequan; Arowo, Moses; Zou, Haikui; Chen, Jianfeng; Shao, Lei

    2016-03-01

    This work investigated the degradation of methyl orange by ozone in the presence of ferrous and persulfate ions (O3/Fe(2+)/S2O8(2-)) in a rotating packed bed. The effects of various operating parameters such as initial pH, rotational speed, gas-liquid ratio, ozone inlet concentration and reaction temperature on the degradation rate of methyl orange were studied with an aim to optimize the operation conditions. Results reveal that the degradation rate increased with an increase in rotational speed, gas-liquid ratio and ozone inlet concentration, and reached a maximum at 25 °C and initial pH 4. Contrast experiments involving ozone and ferrous ions (O3/Fe(2+)) were also carried out, and the results show approximately 10% higher degradation rate and COD removal in the O3/Fe(2+)/S2O8(2-) process than in the O3/Fe(2+) process. Additionally, the intermediates of the degradation process were analyzed to ascertain the degradation products. PMID:26741546

  18. 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.

  19. Heat-activated heat-pump development and potential application of Stirling-engine technology

    NASA Astrophysics Data System (ADS)

    Fairchild, P. D.; West, C. D.

    1982-06-01

    Presented is a brief overview of the heat-activated heat pump technology development program being carried out with emphasis on the Stirling engine technology projects. The major projects are reviewed as they were formulated and carried out under the previous product development guidelines. The revised technology development focus and current status of those major hardware projects are discussed. The key issues involved in applying Stirling engine technology to heat pump equipment are assessed. The approach and planned future activities to address those issues are described. Also included are brief descriptions of two projects in this area supported by the Gas Research Institute.

  20. Activating persulfate by Fe⁰ 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.

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

    SciTech Connect

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

    2005-03-29

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

  2. Demonstration of the Enhanced Disinfection of E. coli Water Contamination by Associated Solar Irradiation with Potassium Persulfate

    PubMed Central

    GHANIZADEH, Ghader; NASERI ARA, Ali; ESMAILI, Davoud; MASOUMBEIGI, Hossein

    2015-01-01

    Background: Tremendous amount of researches have investigated the issue of water photodisnfection. The aim of this research is to illustrate the influences of bacterial density, turbidity, exposure time and potassium persulfate (KPS) dosage on the efficacy of associated solar disinfection (SODIS) with KPS for E. coli (ATCC: 25922) eradication as an efficient and inexpensive process. Methods: Desired bacterial density and turbidity was achieved by spiking of 0.5 Mc Farland (1.5×108 cell/ml) and sterile soil slurry in 1 liter of the commercially bottled water. Results: The highest value of UVA solar irradiation measured at 13.30 p.m was 5510 μW/Cm2. Increase of bacterial density from 1000 to 1500 cell/ml led to an increase in disinfection lapse time, except in 2 mMol/l KPS. Spiking of 0.1 mMol/l of KPS was not effective; however, increase of KPS dosage from 0.1 mMol/l to 0.7, 1.5 and 2 mMol/l led to the enhancement of disinfection time from 4 h to 3 h and 1 h, respectively. For bacterial density of 1000 cell/ml, increasing KPS dosage up to 0.7 mMol/l had no improved effect; however, beyond this dosage the disinfection time decreased to 1 h. Without KPS and up to 150 NTU within 4 h exposure time, E. coli disinfection was completed. In 2 mMol/l KPS and 1000 and 1500 cell/ml, the 2 h contact time was sufficient up to 150 and 100 NTU, respectively; moreover, complete disinfection was not achieved at higher turbidity. Conclusion: Association of KPS with SODIS can lead to decreasing of water disinfection time. PMID:26576351

  3. Lack of Influence of Suspending Media on Heat Activation of Bacillus subtilis Spores and Absence of Deactivation1

    PubMed Central

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

    1964-01-01

    Bacillus subtilis strain 5230 endospores suspended in a variety of suspending media at a concentration of ca. 108 per ml were heated at 95 and 75 C. The effect of the heating at 75 C was measured by plate count, and was reported as the heat-activated decimal fraction of the total viable-spore population. Thermal inactivation at 95 C was influenced by the suspending medium. No effects on heat activation at 75 C were noted for suspending media containing glucose, xylose, ribose, NaCl, or sodium phosphate, nor was there any marked effect due to a change in pH from 5 to 8. The heat-activation response was retained during postheating storage at 5 C in water up to 215 days. Postheating storage in several suspending media for 7 days also indicated no deactivation. PMID:14131357

  4. The effects of heat activation on Bacillus spore germination, with nutrients or under high pressure, with or without various germination proteins.

    PubMed

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

    2015-04-01

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

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

    PubMed Central

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

    2015-01-01

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

  6. [Persulfate asthma in hairdressers].

    PubMed

    Pankow, W; Hein, H; Bittner, K; Wichert, P

    1989-03-01

    At the a two-year apprenticeship, a young female hairdresser developed rhinoconjunctivitis and bronchial asthma, induced by a hair bleach containing the substance persulphate. On each occasion, her symptoms occurred in the form of an immediate reaction. The causative role of the bleach was demonstrated with the aid of an inhalation challenge test. In addition, the prick test produced a positive reaction vis-a-vis persulphate. The long latency period and the positive prick test might militate in favour of an allergic pathomechanism.

  7. [Persulfate asthma in hairdressers].

    PubMed

    Pankow, W; Hein, H; Bittner, K; Wichert, P

    1989-03-01

    At the a two-year apprenticeship, a young female hairdresser developed rhinoconjunctivitis and bronchial asthma, induced by a hair bleach containing the substance persulphate. On each occasion, her symptoms occurred in the form of an immediate reaction. The causative role of the bleach was demonstrated with the aid of an inhalation challenge test. In addition, the prick test produced a positive reaction vis-a-vis persulphate. The long latency period and the positive prick test might militate in favour of an allergic pathomechanism. PMID:2710769

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

    PubMed

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

    2009-09-01

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

  9. Selective disruption of high sensitivity heat activation but not capsaicin activation of TRPV1 channels by pore turret mutations.

    PubMed

    Cui, Yuanyuan; Yang, Fan; Cao, Xu; Yarov-Yarovoy, Vladimir; Wang, KeWei; Zheng, Jie

    2012-04-01

    The capsaicin receptor transient receptor potential vanilloid (TRPV)1 is a highly heat-sensitive ion channel. Although chemical activation and heat activation of TRPV1 elicit similar pungent, painful sensation, the molecular mechanism underlying synergistic activation remains mysterious. In particular, where the temperature sensor is located and whether heat and capsaicin share a common activation pathway are debated. To address these fundamental issues, we searched for channel mutations that selectively affected one form of activation. We found that deletion of the first 10 amino acids of the pore turret significantly reduced the heat response amplitude and shifted the heat activation threshold, whereas capsaicin activation remained unchanged. Removing larger portions of the turret disrupted channel function. Introducing an artificial sequence to replace the deleted region restored sensitive capsaicin activation in these nonfunctional channels. The heat activation, however, remained significantly impaired, with the current exhibiting diminishing heat sensitivity to a level indistinguishable from that of a voltage-gated potassium channel, Kv7.4. Our results demonstrate that heat and capsaicin activation of TRPV1 are structurally and mechanistically distinct processes, and the pore turret is an indispensible channel structure involved in the heat activation process but is not part of the capsaicin activation pathway. Synergistic effect of heat and capsaicin on TRPV1 activation may originate from convergence of the two pathways on a common activation gate.

  10. 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. )

    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.

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

    PubMed

    Ahmadi, Mehdi; Ghanbari, Farshid

    2016-10-01

    Greywater (GW) is a potential source for water reuse in various applications. However, GW treatment is still a vital issue in water reuse in cases of environmental standards and risk to public health. This study investigates optimization and modeling of a hybrid process for COD removal from GW. Persulfate (PS) was simultaneously activated by electrogenerated ferrous ion (EC) and UV to generate sulfate radical. Photoelectro-persulfate (PEPS) was optimized by Box-Behnken design and the effects of four variables (pH, PS dosage, current density, and electrolysis time) were evaluated on COD removal. The results and several coefficients showed that the obtained model was acceptable for predicting the COD removal. Moreover, under optimum conditions (pH = 6.9, PS = 8.8 mM, current density = 2.0 mA/cm(2), and 49.3 min electrolysis time), BOD5, turbidity, TSS, phosphate, and UV254 were effectively removed and COD and BOD5 values reached to discharge standards. Different configurations of the processes were assessed for COD removal. The order of COD removal efficiency followed: PS < Fe(II) < UV/PS ≤ Fe(II)/PS < Fe(II)/PS/UV < electrocoagulation ≤ electrocoagulation/UV < electro-PS < PEPS. The monitoring PS concentration during 60 min reaction time in the aforesaid processes indicated that PEPS could remarkably activate PS. The solution pH was also monitored and related results revealed that the presence of PS during the 10 min first time decreased pH value while production of hydroxide ion at cathode increased pH significantly. Finally, the contribution of electrochemical process in the electrical energy consumption was far less than that of photolysis process in hybrid PEPS process.

  12. 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.

  13. A novel approach for determining total titanium from titanium dioxide nanoparticles suspended in water and biosolids by digestion with ammonium persulfate.

    PubMed

    Khosravi, Kambiz; Hoque, M Ehsanul; Dimock, Brian; Hintelmann, Holger; Metcalfe, Chris D

    2012-02-01

    Titanium dioxide (i.e. TiO(2)) in nano-form is a constituent of many nanomaterials that are used in sunscreens, cosmetics, industrial products and in biomedical applications. Quantification of TiO(2) nanoparticles in various matrixes is a topic of great interest for researchers studying the potential health and environmental impacts of nanoparticles. However, analysis of TiO(2) as Ti(4+) is difficult because current digestion techniques require use of strong acids that may be a health and safety risk in the laboratory. To overcome this problem, we developed a new method to digest TiO(2) nanoparticles using ammonium persulfate as a fusing reagent. The digestion technique requires short times to completion and optimally requires only 1 g of fusing reagent. The fusion method showed >95% recovery of Ti(4+) from 6 μg mL(-1) aqueous suspensions prepared from 10 μg mL(-1) suspension of different forms of TiO(2,) including anatase, rutile and mixed nanosized crystals, and amorphous particles. These recoveries were greater than open hot-plate digestion with a tri-acid solution and comparable to microwave digestion with a tri-acid solution. Cations and anions commonly found in natural waters showed no significant interferences when added to samples in amounts of 10 ng to 110 mg, which is a much broader range of these ions than expected in environmental samples. Using ICP-MS for analysis, the method detection limit (MDL) was determined to be 0.06 ng mL(-1), and the limit of quantification (LOQ) was 0.20 ng mL(-1). Analysis of samples of untreated and treated wastewater and biosolids collected from wastewater treatment plants yielded concentrations of TiO(2) of 1.8 and 1.6 ng mL(-1) for the wastewater samples, respectively, and 317.4 ng mg(-1) dry weights for the biosolids. The reactions between persulfate ions and TiO(2) were evaluated using stoichiometric methods and FTIR and XRD analysis. A formula for the fusing reaction is proposed that involves the formation of sulfate

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

    PubMed

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

    2014-08-01

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

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

    PubMed

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

    2014-08-28

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

  16. Visible-Light-Driven Water Oxidation by a Molecular Manganese Vanadium Oxide Cluster.

    PubMed

    Schwarz, Benjamin; Forster, Johannes; Goetz, McKenna K; Yücel, Duygu; Berger, Claudia; Jacob, Timo; Streb, Carsten

    2016-05-17

    Photosynthetic water oxidation in plants occurs at an inorganic calcium manganese oxo cluster, which is known as the oxygen evolving complex (OEC), in photosystem II. Herein, we report a synthetic OEC model based on a molecular manganese vanadium oxide cluster, [Mn4 V4 O17 (OAc)3 ](3-) . The compound is based on a [Mn4 O4 ](6+) cubane core, which catalyzes the homogeneous, visible-light-driven oxidation of water to molecular oxygen and is stabilized by a tripodal [V4 O13 ](6-) polyoxovanadate and three acetate ligands. When combined with the photosensitizer [Ru(bpy)3 ](2+) and the oxidant persulfate, visible-light-driven water oxidation with turnover numbers of approximately 1150 and turnover frequencies of about 1.75 s(-1) is observed. Electrochemical, mass-spectrometric, and spectroscopic studies provide insight into the cluster stability and reactivity. This compound could serve as a model for the molecular structure and reactivity of the OEC and for heterogeneous metal oxide water-oxidation catalysts.

  17. Visible-Light-Driven Water Oxidation by a Molecular Manganese Vanadium Oxide Cluster.

    PubMed

    Schwarz, Benjamin; Forster, Johannes; Goetz, McKenna K; Yücel, Duygu; Berger, Claudia; Jacob, Timo; Streb, Carsten

    2016-05-17

    Photosynthetic water oxidation in plants occurs at an inorganic calcium manganese oxo cluster, which is known as the oxygen evolving complex (OEC), in photosystem II. Herein, we report a synthetic OEC model based on a molecular manganese vanadium oxide cluster, [Mn4 V4 O17 (OAc)3 ](3-) . The compound is based on a [Mn4 O4 ](6+) cubane core, which catalyzes the homogeneous, visible-light-driven oxidation of water to molecular oxygen and is stabilized by a tripodal [V4 O13 ](6-) polyoxovanadate and three acetate ligands. When combined with the photosensitizer [Ru(bpy)3 ](2+) and the oxidant persulfate, visible-light-driven water oxidation with turnover numbers of approximately 1150 and turnover frequencies of about 1.75 s(-1) is observed. Electrochemical, mass-spectrometric, and spectroscopic studies provide insight into the cluster stability and reactivity. This compound could serve as a model for the molecular structure and reactivity of the OEC and for heterogeneous metal oxide water-oxidation catalysts. PMID:27062440

  18. 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.

  19. Measuring NAPL-Water Interfacial Areas to Evaluate the Effectiveness of In-Situ Chemical Oxidation for DNAPL-Contaminated Source Zones: A Two-Dimensional Flow Cell Study

    NASA Astrophysics Data System (ADS)

    Li, M.; Brusseau, M. L. L.; Yan, N.; Wan, L.

    2015-12-01

    In-situ chemical oxidation (ISCO) using persulfate was employed to remediate a flow cell contaminated with a model dense nonaqueous-phase liquid (DNAPL), trichloroethene (TCE). The flow cell was packed homogeneously with 359 μm diameter natural sand. Dyed TCE DNAPL was naturally distributed in the flow cell. Fe2+-activated persulfate (5 mM) was used for ISCO. Interfacial partitioning tracer tests (IPTT) were conducted before and after ISCO to measure NAPL-water interfacial area, using sodium dodecyl benzenesulfonate (SDBS, 35mg/L) as the tracer. The change in interfacial area was examined as influenced by ISCO remediation. The interfacial areas measured for this two-dimensional system are compared to previously reported values obtained from one-dimensional column experiments.

  20. 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.

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

    PubMed

    Bilgin Oncu, Nalan; Akmehmet Balcioglu, Isil

    2013-10-01

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

  2. A Bioinspired Molecular Polyoxometalate Catalyst with Two Cobalt(II) Oxide Cores for Photocatalytic Water Oxidation.

    PubMed

    Wei, Jie; Feng, Yingying; Zhou, Panpan; Liu, Yan; Xu, Jingyin; Xiang, Rui; Ding, Yong; Zhao, Chongchao; Fan, Linyuan; Hu, Changwen

    2015-08-24

    To overcome the bottleneck of water splitting, the exploration of efficient, selective, and stable water oxidation catalysts (WOCs) is crucial. We report an all-inorganic, oxidatively and hydrolytically stable WOC based on a polyoxometalate [(A-α-SiW9 O34)2Co8(OH)6(H2O)2(CO3)3](16-) (Co8 POM). As a cobalt(II)-based cubane water oxidation catalyst, Co8POM embeds double Co(II)4O3 cores. The self-assembled catalyst is similar to the oxygen evolving complex (OEC) of photosystem II (PS II). Using [Ru(bpy)3](2+) as a photosensitizer and persulfate as a sacrificial electron acceptor, Co8POM exhibits excellent water oxidation activity with a turnover number (TON) of 1436, currently the highest among bioinspired catalysts with a cubical core, and a high initial turnover frequency (TOF). Investigation by several spectroscopy, spectrometry, and other techniques confirm that Co8POM is a stable and efficient catalyst for visible light-driven water oxidation. The results offer a useful insight into the design of water oxidation catalysts.

  3. Comparison between enhanced MALDI in-source decay by ammonium persulfate and N- or C-terminal derivatization methods for detailed peptide structure determination.

    PubMed

    Horvatić, Anita; Dodig, Ivana; Vuletić, Tomislav; Pavoković, Dubravko; Hameršak, Zdenko; Butorac, Ana; Cindrić, Mario

    2013-04-16

    Amino acid sequencing and more detailed structure elucidation analysis of peptides and small proteins is a very difficult task even if state-of-the-art mass spectrometry (MS) is employed. To make this task easier, chemical derivatization methods of the N terminus with 4-sulfophenyl-isothiocyanate (SPITC) or the C terminus with 2-methoxy-4,5-dihydro-1H-imidazole (Lys-tag) can enhance peptide fragmentation or fragment ionizability, via proton mobility/localization mechanisms making tandem MS (MS(2)) spectra more informative and less demanding for structural interpretation. Observed disadvantages related to both derivatization methods are sample- and time-consuming procedures and the increased number of reaction byproducts. A novel, sulfate radical in-source formation method of matrix-assisted laser desorption ionization (MALDI) MS based on chemically enhanced in-source decay (ISD) can be accomplished by simple addition of ammonium persulfate (APS) in the matrix solution. This method enables effective decomposition of peptide ions already in the first stage of MS analysis where a large number of fragment ions are produced. The resultant MALDI-ISD mass spectra (MS after APS → MALDI-ISD MS) are almost equivalent to conventional, collision-induced dissociation (CID) MS(2) spectra. These fragment ions are further subjected to the second stage of the MS, and consequently, MS(3) spectra are produced, which makes the sequence analysis more informative and complete (CID MS(2) is thus equivalent to CID MS(3)). Multiply stage MS after APS addition showed enhanced sensitivity, resolution, and mass accuracy compared to peptide derivatization (SPITC and Lys-tag) or conventional MS and MS(2) analyses and offered more detailed insight into peptide structure.

  4. 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

  5. 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

  6. 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.

  7. 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

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

    SciTech Connect

    Salame, I.I.; Bandosz, T.J. |

    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).

  9. Generating bifunctional fusion enzymes composed of heat-active endoglucanase (Cel5A) and endoxylanase (XylT).

    PubMed

    Rizk, Mazen; Elleuche, Skander; Antranikian, Garabed

    2015-01-01

    Bifunctional enzyme constructs were generated comprising two genes encoding heat-active endoglucanase (cel5A) and endoxylanase (xylT). The fused proteins Cel5A-XylT and XylT-Cel5A were active on both β-glucan and beechwood xylan. An improvement in endoglucanase and endoxylanase catalytic activities was observed. The specific activity of the fusion towards xylan was significantly raised when compared to XylT. The fusion constructs were active from 40 to 100 °C for endoglucanase and from 40 to 90 °C for endoxylanase, but the temperature optima were lowered from 90 to 80 °C for the endoglucanase and from 80 to 70 °C for the endoxylanase. XylT in the construct XylT-Cel5A was less stable at higher temperatures compared to Cel5A-XylT. Due to the enzymatic performance, these fusion enzymes are attractive candidates for applications in biorefineries based on plant waste.

  10. 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

  11. 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.

  12. 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.

  13. 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.

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

    PubMed Central

    Qin, Feng

    2015-01-01

    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

  15. A pulsed electron beam synthesis of PEDOT conducting polymers by using sulfate radicals as oxidizing species

    NASA Astrophysics Data System (ADS)

    Coletta, Cecilia; Cui, Zhenpeng; Dazzi, Alexandre; Guigner, Jean-Michel; Néron, Stéphane; Marignier, Jean-Louis; Remita, Samy

    2016-09-01

    In this study, an original radiolytic method, based on pulsed electron beam irradiation, is used for the synthesis of conducting PEDOT in an aqueous solution containing EDOT monomers in the presence of potassium persulfate, K2S2O8, at 0 °C. At this low temperature, EDOT monomers are not chemically oxidized by S2O82- anions, initiating PEDOT polymerization, but are rather oxidized by sulfate radicals, SO4•-, which are radiolytically generated by the reaction of solvated electrons, produced by water radiolysis, with persulfate anions. Successfully, as demonstrated by UV-vis absorption spectrophotometry and ATR-FTIR spectroscopy, irradiating the aqueous solution, by using a series of accumulated electron pulses, enables complete EDOT oxidation and quantitative in situ PEDOT polymerization through a step-by-step oxidation mechanism. The morphology of PEDOT polymers, mixed with unreacted K2S2O8 salt, is characterized by Cryo-TEM microscopy in aqueous solution and by SEM after deposition. Successfully, in the absence of any washing step, high resolution AFM microscopy, coupled with infrared nanospectroscopy, is used to discriminate between the organic polymers and the inorganic salt and to probe the local chemical composition of PEDOT nanostructures. The results demonstrate that PEDOT polymers form globular self-assembled nanostructures which preferentially adsorb onto unreacted K2S2O8 solid nanoplates. The present results first demonstrate the efficiency of sulfate radicals as oxidizing species for the preparation of nanostructured PEDOT polymers and second highlight the promising potentiality of electron accelerators in the field of conducting polymers synthesis.

  16. [The problem of heat activation of bacterial spores after disinfection with regard to an aerosol method of decontaminating equipment and rooms].

    PubMed

    Fuhrmann, H; Floerke, I; Böhm, K H

    1986-10-01

    This paper describes investigations on disinfection of germ carriers, contaminated with an alcoholic suspension of Bacillus cereus or Bacillus subtilis. Result of disinfection is compared with that of an additional heat treatment (80 degrees C, 60 min) after disinfection. Besides Formalin, Tegodor forte (Th. Goldschmidt, Essen) and P 3 oxonia active (Henkel KG, Düsseldorf) are tested with different concentration and duration. Heat activation was possible with all three disinfectants. For illuminating the conditions of activation, circumstances of heat action after disinfection with formaldehyde-aerosol have been varied. Heat activation in dry air, moist air and distilled water was not successful. Only in Nutrient Broth (Standard I-Bouillon; Merck, Darmstadt) spores were viable again, after activation. Addition of serum as a protective cover had no influence on the result. Consequences of the results on a disinfection method with formaldehyde-aerosol are discussed.

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

    PubMed

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

    2001-01-01

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

  18. The influence of a non-aqueous phase liquid (NAPL) and chemical oxidant application on perfluoroalkyl acid (PFAA) fate and transport.

    PubMed

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

    2016-04-01

    One dimensional column experiments were conducted using saturated porous media containing residual trichloroethylene (TCE) to understand the effects of non-aqueous phase liquids (NAPLs) and chemical oxidation on perfluoroalkyl acid (PFAA) fate and transport. Observed retardation factors and data from supporting batch studies suggested that TCE provides additional sorption capacity that can increase PFAA retardation (i.e., decreased mobility), though the mechanisms remain unclear. Treatment with persulfate activated with FeCl2 and citric acid, catalyzed hydrogen peroxide (CHP), or permanganate did not result in oxidative transformations of PFAAs. However, impacts on PFAA sorption were apparent, and enhanced sorption was substantial in the persulfate-treated columns. In contrast, PFAA transport was accelerated in permanganate- and CHP-treated columns. Ultimately, PFAA transport in NAPL contaminated groundwater is likely influenced by porous media properties, NAPL characteristics, and water quality properties, each of which can change due to chemical oxidant treatment. For contaminated sites for which ISCO is a viable treatment option, changes to PFAA transport and the implications thereof should be included as a component of the remediation evaluation and selection process. PMID:26854608

  19. The influence of a non-aqueous phase liquid (NAPL) and chemical oxidant application on perfluoroalkyl acid (PFAA) fate and transport.

    PubMed

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

    2016-04-01

    One dimensional column experiments were conducted using saturated porous media containing residual trichloroethylene (TCE) to understand the effects of non-aqueous phase liquids (NAPLs) and chemical oxidation on perfluoroalkyl acid (PFAA) fate and transport. Observed retardation factors and data from supporting batch studies suggested that TCE provides additional sorption capacity that can increase PFAA retardation (i.e., decreased mobility), though the mechanisms remain unclear. Treatment with persulfate activated with FeCl2 and citric acid, catalyzed hydrogen peroxide (CHP), or permanganate did not result in oxidative transformations of PFAAs. However, impacts on PFAA sorption were apparent, and enhanced sorption was substantial in the persulfate-treated columns. In contrast, PFAA transport was accelerated in permanganate- and CHP-treated columns. Ultimately, PFAA transport in NAPL contaminated groundwater is likely influenced by porous media properties, NAPL characteristics, and water quality properties, each of which can change due to chemical oxidant treatment. For contaminated sites for which ISCO is a viable treatment option, changes to PFAA transport and the implications thereof should be included as a component of the remediation evaluation and selection process.

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

    PubMed

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

    2009-09-15

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

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

    PubMed

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

    2014-07-01

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

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

    PubMed

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

    2014-03-01

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

  3. 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.

  4. Extraction and comparison of carboxylated cellulose nanocrystals from bleached sugarcane bagasse pulp using two different oxidation methods.

    PubMed

    Zhang, Kaitao; Sun, Peipei; Liu, He; Shang, Shibin; Song, Jie; Wang, Dan

    2016-03-15

    Two kinds of carboxylated cellulose nanocrystals (CCNs) were prepared by using ultrasonic assisted 2,2,6,6-tetramethylpiperidinyl-1-oxy radical (TEMPO) mediated oxidation and one-step ammonium persulfate (APS) oxidation, which were denoted as TEMPO-oxidized CCNs (TO-CCNs) and APS-oxidized CCNs (AO-CCNs), respectively. The effects of oxidant content on the yield, carboxyl content, degree of polymerization (DPv) and morphology of the oxidized celluloses in the two oxidation methods were studied. Furthermore, the chemical structure, crystallinity and thermal stability of TO-CCNs and AO-CCNs were evaluated and compared by Fourier transformed infrared spectra, X-ray diffraction and thermogravimetric analyses. The results showed that with increase of oxidant content in the two methods, the carboxyl groups on the surfaces of TO-CCNs and AO-CCNs were both improved. And a remarkable decline of the DPv of cellulose sample also appeared in the two oxidative treatments. In addition, AO-CCNs exhibited a higher crystallinity and an enhanced thermal stability compared with TO-CCNs. PMID:26794758

  5. 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 ...

  6. Removal of PCBs in contaminated soils by means of chemical reduction and advanced oxidation processes.

    PubMed

    Rybnikova, V; Usman, M; Hanna, K

    2016-09-01

    Although the chemical reduction and advanced oxidation processes have been widely used individually, very few studies have assessed the combined reduction/oxidation approach for soil remediation. In the present study, experiments were performed in spiked sand and historically contaminated soil by using four synthetic nanoparticles (Fe(0), Fe/Ni, Fe3O4, Fe3 - x Ni x O4). These nanoparticles were tested firstly for reductive transformation of polychlorinated biphenyls (PCBs) and then employed as catalysts to promote chemical oxidation reactions (H2O2 or persulfate). Obtained results indicated that bimetallic nanoparticles Fe/Ni showed the highest efficiency in reduction of PCB28 and PCB118 in spiked sand (97 and 79 %, respectively), whereas magnetite (Fe3O4) exhibited a high catalytic stability during the combined reduction/oxidation approach. In chemical oxidation, persulfate showed higher PCB degradation extent than hydrogen peroxide. As expected, the degradation efficiency was found to be limited in historically contaminated soil, where only Fe(0) and Fe/Ni particles exhibited reductive capability towards PCBs (13 and 18 %). In oxidation step, the highest degradation extents were obtained in presence of Fe(0) and Fe/Ni (18-19 %). The increase in particle and oxidant doses improved the efficiency of treatment, but overall degradation extents did not exceed 30 %, suggesting that only a small part of PCBs in soil was available for reaction with catalyst and/or oxidant. The use of organic solvent or cyclodextrin to improve the PCB availability in soil did not enhance degradation efficiency, underscoring the strong impact of soil matrix. Moreover, a better PCB degradation was observed in sand spiked with extractable organic matter separated from contaminated soil. In contrast to fractions with higher particle size (250-500 and <500 μm), no PCB degradation was observed in the finest fraction (≤250 μm) having higher organic matter content. These findings

  7. The chimeric approach reveals that differences in the TRPV1 pore domain determine species-specific sensitivity to block of heat activation.

    PubMed

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

    2011-11-11

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

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed Central

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

    2015-01-01

    In this study, we demonstrated an oxidative method with free radical to generate 3,5,4′-trihydroxy-trans-stilbene (trans-resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI–MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4′-dihydroxy-trans-stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI–MS/MS can be utilized to evaluate different metabolites in various conditions. PMID:27594817

  10. Self-flocculated powdered activated carbon with different oxidation methods and their influence on adsorption behavior.

    PubMed

    Gong, Zailin; Li, Shujin; Ma, Jun; Zhang, Xiangdong

    2016-03-01

    The commercial powdered activated carbon (PAC) has been selectively oxidized by two methods. The two oxidized methods are wet oxidation with ammonium persulfate and thermal treatment after acidification with hydrochloride acid, respectively. The two oxidized PAC were then functionalized with thermoresponsive poly (N-isopropylacrylamide) (PNIPAM) in aqueous solution at ambient temperature. Comparing the two oxidized PAC products and their grafted derivatives, the oxidized PAC modified with thermal treatment after acidification shows larger surface area of 1184 m(2)/g and better adsorption of bisphenol A. Its derivative also exhibits relatively large surface area and adsorption capacity after grafted with PNIPAM. The maximum surface adsorption capacity simulated under Langmuir Models reached 156 mg/g. In addition, the grafted PAC products show self-flocculation behaviors with rapid response to temperature because of the thermal phase transition and entanglement behaviors of PNIPAM. The present study provides a new way to obtain carboxyl-rich activated carbon with large surface area and better adsorption capacity. The retrievable grafted PAC with good self-flocculation effect responsive to temperature will have high potential application in water remediation which requires pre-heating and emergency water treatment in the wild. PMID:26551226

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

    PubMed

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

    2011-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Pendleton, Phillip; Chen, Lin

    2006-11-01

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

  13. Oxidative degradation of food dye E133 Brilliant Blue FCF Liquid chromatography-electrospray mass spectrometry identification of the degradation pathway.

    PubMed

    Gosetti, F; Gianotti, V; Angioi, S; Polati, S; Marengo, E; Gennaro, M C

    2004-10-29

    This paper is devoted to the evaluation of the degradation pathway of the E133 Brilliant Blue FCF (C.I. 42090) that is largely used in the food industry. The degradation is studied in oxidation conditions obtained by addition of potassium persulfate at different persulfate to dye molar ratios under natural sunlight irradiation. The degradation pathway of the dye passes through a species coloured in dark blue and then gives rise to uncoloured species. Due to the low volatility and the poor thermal stability of the dye, reversed-phase liquid chromatography associated to mass spectrometry and tandom mass spectrometry was employed to follow the kinetics of degradation and identify some intermediates. The identification of organic species still present in the decoloured dye and the value of COD obtained in these conditions show evidence that complete decolorization does not correspond to complete mineralisation. No direct information of toxicity is available for the uncoloured degradation products but the further formation of aromatic amines can not be excluded.

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

    PubMed

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

    2014-01-21

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

  15. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of nonpurgeable suspended organic carbon by wet-chemical oxidation and infrared spectrometry

    USGS Publications Warehouse

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

    1997-01-01

    Precision and accuracy results are described for the determination of nonpurgeable suspended organic carbon (SOC) by silver-filter filtration, wet-chemical oxidation, and infrared determination of hte resulting carbon dioxide (CO2) used at the U.S. Geological Survey's nationalWater Quality Laboratory. An aliquot of raw water isfiltered through a 0.45-micrometer silver filter. The trapped organic material is oxidized using phosphoric acid and potassium persulfate in a scaled glass ampule,and the rseulting CO2 is measured by an infrared CO2 detector. The amount of CO3 is proportional to the concentration of chemically oxidizable nonpurgeable organic carbon in the sample. The SOC method detection limit for routine analysis is 0.2 milligram per liter. The average percent recovery is 97.1 percent and the average standard deviation is 11 percent.

  16. Halogenated earth abundant metalloporphyrins as photostable sensitizers for visible-light-driven water oxidation in a neutral phosphate buffer solution.

    PubMed

    Chen, Hung-Cheng; Reek, Joost N H; Williams, René M; Brouwer, Albert M

    2016-06-01

    Very photostable tetrachloro-metalloporphyrins were developed as sensitizers for visible-light-driven water oxidation coupled to cobalt based water-oxidation catalysts in concentrated (0.1 M) phosphate buffer solution. Potassium persulfate (K2S2O8) acts as a sacrificial electron acceptor to oxidize the metalloporphyrin photosensitizers in their excited states. The radical cations thus produced drive the cobalt based water-oxidation catalysts: Co4O4-cubane and Co(NO3)2 as pre-catalyst for cobalt-oxide (CoOx) nanoparticles. Two different metalloporphyrins (Cu(ii) and Ni(ii)) both showed very high photostability in the photocatalytic reaction, as compared to non-halogenated analogues. This indicates that photostability primarily depends on the substitution of the porphyrin macrocycle, not on the central metal. Furthermore, our molecular design strategy not only positively increases the electrochemical potential by 120-140 mV but also extends the absorption spectrum up to ∼600 nm. As a result, the solar photon capturing abilities of halogenated metalloporphyrins (Cu(ii) and Ni(ii)) are comparable to that of the natural photosynthetic pigment, chlorophyll a. We successfully demonstrate long-term (>3 h) visible-light-driven water oxidation using our molecular system based on earth-abundant (first-row transition) metals in concentrated phosphate buffer solution.

  17. Halogenated earth abundant metalloporphyrins as photostable sensitizers for visible-light-driven water oxidation in a neutral phosphate buffer solution.

    PubMed

    Chen, Hung-Cheng; Reek, Joost N H; Williams, René M; Brouwer, Albert M

    2016-06-01

    Very photostable tetrachloro-metalloporphyrins were developed as sensitizers for visible-light-driven water oxidation coupled to cobalt based water-oxidation catalysts in concentrated (0.1 M) phosphate buffer solution. Potassium persulfate (K2S2O8) acts as a sacrificial electron acceptor to oxidize the metalloporphyrin photosensitizers in their excited states. The radical cations thus produced drive the cobalt based water-oxidation catalysts: Co4O4-cubane and Co(NO3)2 as pre-catalyst for cobalt-oxide (CoOx) nanoparticles. Two different metalloporphyrins (Cu(ii) and Ni(ii)) both showed very high photostability in the photocatalytic reaction, as compared to non-halogenated analogues. This indicates that photostability primarily depends on the substitution of the porphyrin macrocycle, not on the central metal. Furthermore, our molecular design strategy not only positively increases the electrochemical potential by 120-140 mV but also extends the absorption spectrum up to ∼600 nm. As a result, the solar photon capturing abilities of halogenated metalloporphyrins (Cu(ii) and Ni(ii)) are comparable to that of the natural photosynthetic pigment, chlorophyll a. We successfully demonstrate long-term (>3 h) visible-light-driven water oxidation using our molecular system based on earth-abundant (first-row transition) metals in concentrated phosphate buffer solution. PMID:27197873

  18. The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

    PubMed

    Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

    2016-07-01

    In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. PMID:27372125

  19. Nitrogen- and Sulfur-Codoped Hierarchically Porous Carbon for Adsorptive and Oxidative Removal of Pharmaceutical Contaminants.

    PubMed

    Tian, Wenjie; Zhang, Huayang; Duan, Xiaoguang; Sun, Hongqi; Tade, Moses O; Ang, Ha Ming; Wang, Shaobin

    2016-03-23

    Heteroatom (nitrogen and sulfur)-codoped porous carbons (N-S-PCs) with high surface areas and hierarchically porous structures were successfully synthesized via direct pyrolysis of a mixture of glucose, sodium bicarbonate, and thiourea. The resulting N-S-PCs exhibit excellent adsorption abilities and are highly efficient for potassium persulfate activation when employed as catalysts for the oxidative degradation of sulfachloropyridazine (SCP) solutions. The adsorption capacities of N-S-PC-2 (which contains 4.51 atom % nitrogen and 0.22 atom % sulfur and exhibits SBET of 1608 m(2) g(-1)) are 73, 7, and 3 times higher than those of graphene oxide, reduced graphene oxide, and commercial single-walled carbon nanotube, respectively. For oxidation, the reaction rate constant of N-S-PC-2 is 0.28 min(-1). This approach not only contributes to the large-scale production and application of high-quality catalysts in water remediation but also provides an innovative strategy for the production of heteroatom-doped PCs for energy applications. PMID:26937827

  20. Effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement

    PubMed Central

    Shin, Tae-Bong; Lee, Joo-Hee; Ahn, Kang-Min; Kim, Tae-Hyung

    2016-01-01

    PURPOSE To evaluate the effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement. MATERIALS AND METHODS The specimens were prepared to evaluate the bond strength of epoxy resin-based fiber posts (D.T. Light-Post) to dual-curing resin cement (RelyX U200). The specimens were divided into four groups (n=18) according to different surface treatments: group 1, no treatment; group 2, silanization; group 3, silanization after hydrogen peroxide etching; group 4, silanization with warm drying at 80℃ after hydrogen peroxide etching. After storage of the specimens in distilled water at 37℃ for 24 hours, the shear bond strength (in MPa) between the fiber post and resin cement was measured using a universal testing machine. The fractured surface of the fiber post was examined using scanning electron microscopy. Data were analyzed using one-way ANOVA and post-hoc analysis with Tukey's HSD test (α=0.05). RESULTS Silanization of the fiber post (Group 2) significantly increased the bond strength in comparison with the non treated control (Group 1) (P<.05). Heat drying after silanization also significantly increased the bond strength (Group 3 and 4) (P<.05). However, no effect was determined for hydrogen peroxide etching before applying silane agent (Group 2 and 3) (P>.05). CONCLUSION Fiber post silanization and subsequent heat treatment (80℃) with warm air blower can be beneficial in clinical post cementation. However, hydrogen peroxide etching prior to silanization was not effective in this study. PMID:27141252

  1. The Effect of Artificial Aging on The Bond Strength of Heat-activated Acrylic Resin to Surface-treated Nickel-chromium-beryllium Alloy

    PubMed Central

    Al Jabbari, Youssef S.; Zinelis, Spiros; Al Taweel, Sara M.; Nagy, William W.

    2016-01-01

    Purpose The debonding load of heat-activated polymethylmethacrylate (PMMA) denture base resin material to a nickel-chromium-beryllium (Ni-Cr-Be) alloy conditioned by three different surface treatments and utilizing two different commercial bonding systems was investigated. Materials and Methods Denture resin (Lucitone-199) was bonded to Ni-Cr-Be alloy specimens treated with Metal Primer II, the Rocatec system with opaquer and the Rocatec system without opaquer. Denture base resin specimens bonded to non-treated sandblasted Ni-Cr-Be alloy were used as controls. Twenty samples for each treatment condition (80 specimens) were tested. The 80 specimens were divided into two categories, thermocycled and non-thermocycled, containing four groups of ten specimens each. The non-thermocycled specimens were tested after 48 hours’ storage in room temperature water. The thermocycled specimens were tested after 2,000 cycles in 4°C and 55°C water baths. The debonding load was calculated in Newtons (N), and collected data were subjected by non parametric test Kruskal-Wallis One Way Analysis of Variance on Ranks and Dunn’s post hoc test at the α = 0.05. Results The Metal Primer II and Rocatec system without opaquer groups produced significantly higher bond strengths (119.9 and 67.6 N), respectively, than did the sandblasted and Rocatec system with opaquer groups, where the bond strengths were 2.6 N and 0 N, respectively. The Metal Primer II was significantly different from all other groups (P<0.05). The bond strengths of all groups were significantly decreased (P<0.05) after thermocycling. Conclusions Although thermocycling had a detrimental effect on the debonding load of all surface treatments tested, the Metal Primer II system provided higher values among all bonding systems tested, before and after thermocycling. PMID:27335613

  2. Activation of Peroxymonosulfate by Surface-Loaded Noble Metal Nanoparticles for Oxidative Degradation of Organic Compounds.

    PubMed

    Ahn, Yong-Yoon; Yun, Eun-Tae; Seo, Ji-Won; Lee, Changha; Kim, Sang Hoon; Kim, Jae-Hong; Lee, Jaesang

    2016-09-20

    This study demonstrates the capability of noble metal nanoparticles immobilized on Al2O3 or TiO2 support to effectively activate peroxymonosulfate (PMS) and degrade select organic compounds in water. The noble metals outperformed a benchmark PMS activator such as Co(2+) (water-soluble) for PMS activation and organic compound degradation at acidic pH and showed the comparable activation capacity at neutral pH. The efficiency was found to depend on the type of noble metal (following the order of Pd > Pt ≈ Au ≫ Ag), the amount of noble metal deposited onto the support, solution pH, and the type of target organic substrate. In contrast to common PMS-activated oxidation processes that involve sulfate radical as a main oxidant, the organic compound degradation kinetics were not affected by sulfate radical scavengers and exhibited substrate dependency that resembled the PMS activated by carbon nanotubes. The results presented herein suggest that noble metals can mediate electron transfer from organic compounds to PMS to achieve persulfate-driven oxidation, rather than through reductive conversion of PMS to reactive sulfate radical. PMID:27564590

  3. Activation of Peroxymonosulfate by Surface-Loaded Noble Metal Nanoparticles for Oxidative Degradation of Organic Compounds.

    PubMed

    Ahn, Yong-Yoon; Yun, Eun-Tae; Seo, Ji-Won; Lee, Changha; Kim, Sang Hoon; Kim, Jae-Hong; Lee, Jaesang

    2016-09-20

    This study demonstrates the capability of noble metal nanoparticles immobilized on Al2O3 or TiO2 support to effectively activate peroxymonosulfate (PMS) and degrade select organic compounds in water. The noble metals outperformed a benchmark PMS activator such as Co(2+) (water-soluble) for PMS activation and organic compound degradation at acidic pH and showed the comparable activation capacity at neutral pH. The efficiency was found to depend on the type of noble metal (following the order of Pd > Pt ≈ Au ≫ Ag), the amount of noble metal deposited onto the support, solution pH, and the type of target organic substrate. In contrast to common PMS-activated oxidation processes that involve sulfate radical as a main oxidant, the organic compound degradation kinetics were not affected by sulfate radical scavengers and exhibited substrate dependency that resembled the PMS activated by carbon nanotubes. The results presented herein suggest that noble metals can mediate electron transfer from organic compounds to PMS to achieve persulfate-driven oxidation, rather than through reductive conversion of PMS to reactive sulfate radical.

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

    PubMed

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

    2015-09-01

    A reaction-based probe 1 for hypochlorite signaling was designed by the conjugation of two fluorophores, rhodamine and dansyl moieties, by the reaction of rhodamine B base with dansylhydrazine. Probe 1 exhibited pronounced hypochlorite-selective chromogenic and fluorescent signaling behavior over other oxidants used in practical applications, such as hydrogen peroxide, peracetic acid, and ammonium persulfate, as well as commonly encountered metal ions and anions. Signaling was attributed to the hypochlorite-induced oxidative cleavage of the sulfonhydrazide linkage of the probe. In particular, favorable ratiometric fluorescence signaling was possible by utilizing the emissions of the two fluorophores. A detection limit of 1.13 × 10(-6) M (0.058 ppm) was estimated for the determination of hypochlorite. A paper-based test strip was prepared and was used as a semiquantitative indicator for the presence of hypochlorite in aqueous solutions. The probe was also successfully applied for the determination of hypochlorite in practical tap water samples. PMID:26313428

  5. Erythromycin oxidation and ERY-resistant Escherichia coli inactivation in urban wastewater by sulfate radical-based oxidation process under UV-C irradiation.

    PubMed

    Michael-Kordatou, I; Iacovou, M; Frontistis, Z; Hapeshi, E; Dionysiou, D D; Fatta-Kassinos, D

    2015-11-15

    This study evaluates the feasibility of UV-C-driven advanced oxidation process induced by sulfate radicals SO4(.)- in degrading erythromycin (ERY) in secondary treated wastewater. The results revealed that 10 mg L(-1) of sodium persulfate (SPS) can result in rapid and complete antibiotic degradation within 90 min of irradiation, while ERY decay exhibited a pseudo-first-order kinetics pattern under the different experimental conditions applied. ERY degradation rate was strongly affected by the chemical composition of the aqueous matrix and it decreased in the order of: ultrapure water (kapp = 0.55 min(-1)) > bottled water (kapp = 0.26 min(-1)) > humic acid solution (kapp = 0.05 min(-1)) > wastewater effluents (kapp = 0.03 min(-1)). Inherent pH conditions (i.e. pH 8) yielded an increased ERY degradation rate, compared to that observed at pH 3 and 5. The contribution of hydroxyl and sulfate radicals (HO. and SO4(.)-) on ERY degradation was found to be ca. 37% and 63%, respectively. Seven transformation products (TPs) were tentatively elucidated during ERY oxidation, with the 14-membered lactone ring of the ERY molecule being intact in all cases. The observed phytotoxicity against the tested plant species can potentially be attributed to the dissolved effluent organic matter (dEfOM) present in wastewater effluents and its associated-oxidation products and not to the TPs generated from the oxidation of ERY. This study evidences the potential use of the UV-C/SPS process in producing a final treated effluent with lower phytotoxicity (<10%) compared to the untreated wastewater. Finally, under the optimum experimental conditions, the UV-C/SPS process resulted in total inactivation of ERY-resistant Escherichia coli within 90 min.

  6. Erythromycin oxidation and ERY-resistant Escherichia coli inactivation in urban wastewater by sulfate radical-based oxidation process under UV-C irradiation.

    PubMed

    Michael-Kordatou, I; Iacovou, M; Frontistis, Z; Hapeshi, E; Dionysiou, D D; Fatta-Kassinos, D

    2015-11-15

    This study evaluates the feasibility of UV-C-driven advanced oxidation process induced by sulfate radicals SO4(.)- in degrading erythromycin (ERY) in secondary treated wastewater. The results revealed that 10 mg L(-1) of sodium persulfate (SPS) can result in rapid and complete antibiotic degradation within 90 min of irradiation, while ERY decay exhibited a pseudo-first-order kinetics pattern under the different experimental conditions applied. ERY degradation rate was strongly affected by the chemical composition of the aqueous matrix and it decreased in the order of: ultrapure water (kapp = 0.55 min(-1)) > bottled water (kapp = 0.26 min(-1)) > humic acid solution (kapp = 0.05 min(-1)) > wastewater effluents (kapp = 0.03 min(-1)). Inherent pH conditions (i.e. pH 8) yielded an increased ERY degradation rate, compared to that observed at pH 3 and 5. The contribution of hydroxyl and sulfate radicals (HO. and SO4(.)-) on ERY degradation was found to be ca. 37% and 63%, respectively. Seven transformation products (TPs) were tentatively elucidated during ERY oxidation, with the 14-membered lactone ring of the ERY molecule being intact in all cases. The observed phytotoxicity against the tested plant species can potentially be attributed to the dissolved effluent organic matter (dEfOM) present in wastewater effluents and its associated-oxidation products and not to the TPs generated from the oxidation of ERY. This study evidences the potential use of the UV-C/SPS process in producing a final treated effluent with lower phytotoxicity (<10%) compared to the untreated wastewater. Finally, under the optimum experimental conditions, the UV-C/SPS process resulted in total inactivation of ERY-resistant Escherichia coli within 90 min. PMID:26360228

  7. 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.

  8. 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

  9. 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.

  10. Magnesium Oxide

    MedlinePlus

    ... different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. ... stomach.Do not take magnesium oxide as an antacid for longer than 2 weeks unless your doctor ...

  11. A case of chemical scalp burns after hair highlights: experimental evidence of oxidative injuries.

    PubMed

    Bertani, Roberta; Sgarbossa, Paolo; Pendolino, Flavio; Facchin, Giangiacomo; Snenghi, Rossella

    2016-12-01

    Hair highlights are quite common procedures carried out in hair salons by using a mixture of a lightening powder containing persulfates with a suspension containing hydrogen peroxide: a representative case of chemical scalp burns is described as a consequence of this treatment. The aim of the paper is to demonstrate the strict relationship between the scalp damage and the commercial products used in a case of hair highlighting. The results of some chemical analyses have been reported, showing, in particular, that the chemical reactivity of the mixture changes in the time, thus strongly suggesting that the procedure for the application of the mixture is critical for the occurrence of possible accidents. The presence in the powder of chemical compounds bearing aliphatic chains as surfactants explains the appearance of dramatic symptoms after days due to a slow dissolution of the oxidant compounds in the stratum corneum of skin with no effect in reducing injury of palliative treatments. Safety suggestions and recommendations for producers and workers are also included.

  12. 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

  13. Oxide Thermoelectrics

    SciTech Connect

    Singh, David J

    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.

  14. Oxidation catalyst

    DOEpatents

    Ceyer, Sylvia T.; Lahr, David L.

    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.

  15. 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

  16. Thallium oxide

    Integrated Risk Information System (IRIS)

    Thallium oxide ; CASRN 1314 - 32 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  17. Propylene oxide

    Integrated Risk Information System (IRIS)

    Propylene oxide ; CASRN 75 - 56 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  18. Nitric oxide

    Integrated Risk Information System (IRIS)

    Nitric oxide ; CASRN 10102 - 43 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  19. Merphos oxide

    Integrated Risk Information System (IRIS)

    Merphos oxide ; CASRN 78 - 48 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  20. 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

  1. 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

  2. Oxide surfaces.

    PubMed

    Willmott, Phil

    2008-07-01

    Although the history of metal oxides and their surfaces goes back several decades to landmark studies, such as Mott and Peierls' explanation of electrical insulation in materials that are predicted in band theory to be conducting, or the observation by Morin of the superfast metal-to-insulator transition in vanadium dioxide, it is only in the last two decades that the world of condensed matter physics has become increasingly dominated by research into complex metal oxides. This has been driven most notably by an attempt to better understand and describe the fundamental physical processes behind their seemingly endless spectrum of properties, which in turn has also led to the discovery of novel phenomena, most prominently demonstrated by the discovery of high-temperature superconductivity in 1986, colossal magnetoresistance in 1994, and most recently, the formation of a two-dimensional conducting layer at the interface between two band insulators in 2004. One important reason why metal oxides, particularly in the form of thin films, have become such a popular subject for basic condensed matter research is that they offer a uniquely versatile materials base for the development of novel technologies. They owe this versatility both to the many different elemental combinations that lead to structurally similar forms, and also to the fact that in many cases, the strong interaction between the valence electrons means that there is a subtle interplay between structure and magnetic and electronic properties. This aspect has led in recent years to the birth or renaissance of research fields such as spintronics, orbital ordering, and multiferroics. Surfaces and interfaces are especially interesting in these strongly-correlated electron systems, where the rearrangement of electrical charge resulting from a minimization of surface or interfacial energy can have unexpected and often exciting consequences. Indeed, as the drive to miniaturize devices well below the micron size

  3. 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

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

    PubMed

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

    2014-06-28

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

  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 π-π 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.

  6. 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 π-π 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

  7. Formation of halogenated disinfection by-products in cobalt-catalyzed peroxymonosulfate oxidation processes in the presence of halides.

    PubMed

    Xie, Weiping; Dong, Wei; Kong, Deyang; Ji, Yuefei; Lu, Junhe; Yin, Xiaoming

    2016-07-01

    Sulfate radicals (SO4(-)) generated by activation of peroxymonosulfate (PMS) and persulfate (PS) are highly oxidative and applied to degrade various organic pollutants. This research was designed to investigate formation of halogenated by-products in Co(2+) activated PMS process in the presence of halides and natural organic matter (NOM). It was revealed that no halogenated by-products were detected in the presence of Cl(-) while 189 μg/L bromoform and 100.7 μg/L dibromoacetic acid (DBAA) were found after 120 h when 2 mg/L NOM, 0.1 mM Br(-), 1.0 mM PMS, and 5 μL Co(2+) were present initially. These products are known as disinfection by-products (DBPs) since they are formed in water disinfection processes. Formation of DBPs was even more significant in the absence of Co(2+). The data indicate that both PMS and SO4(-) can transform Br(-) to reactive bromine species which react with NOM to form halogenated by-products. Less DBP formation in Co(2+)-PMS systems was due to the further destruction of DBPs by SO4(-). More DBPs species including chlorinated ones were detected in the presence of both Cl(-) and Br(-). However, more brominated species produced than chlorinate ones generally. The total DBP yield decreased with the increase of Cl(-) content when total halides kept constant. This is one of the few studies that demonstrate the formation of halogenated DBPs in Co(2+)/PMS reaction systems, which should be taken into consideration in the application of SO4(-) based oxidation technologies. PMID:27093695

  8. 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.

  9. Nitric oxide inhibition strategies

    PubMed Central

    Wong, Vivian (Wai Chong); Lerner, Ethan

    2015-01-01

    Nitric oxide is involved in many physiologic processes. There are efforts, described elsewhere in this volume, to deliver nitric oxide to tissues as a therapy. Nitric oxide also contributes to pathophysiologic processes. Inhibiting nitric oxide or its production can thus also be of therapeutic benefit. This article addresses such inhibitory strategies. PMID:26634146

  10. Electrochemical oxidation of cholesterol

    PubMed Central

    2015-01-01

    Summary Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and affords different products depending on the reaction conditions. PMID:25977713

  11. 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.

  12. Photo-oxidation catalysts

    DOEpatents

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

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

  13. 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

  14. Vascular oxidative stress, nitric oxide and atherosclerosis.

    PubMed

    Li, Huige; Horke, Sven; Förstermann, Ulrich

    2014-11-01

    In the vascular wall, reactive oxygen species (ROS) are produced by several enzyme systems including NADPH oxidase, xanthine oxidase, uncoupled endothelial nitric oxide synthase (eNOS) and the mitochondrial electron transport chain. On the other hand, the vasculature is protected by antioxidant enzyme systems, including superoxide dismutases, catalase, glutathione peroxidases and paraoxonases, which detoxify ROS. Cardiovascular risk factors such as hypercholesterolemia, hypertension, and diabetes mellitus enhance ROS generation, resulting in oxidative stress. This leads to oxidative modification of lipoproteins and phospholipids, mechanisms that contribute to atherogenesis. In addition, oxidation of tetrahydrobiopterin may cause eNOS uncoupling and thus potentiation of oxidative stress and reduction of eNOS-derived NO, which is a protective principle in the vasculature. This review summarizes the latest advances in the role of ROS-producing enzymes, antioxidative enzymes as well as NO synthases in the initiation and development of atherosclerosis.

  15. Electrolytic oxidation of anthracite

    USGS Publications Warehouse

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

    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.

  16. Zinc oxide overdose

    MedlinePlus

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...

  17. 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.

  18. Mixed Acid Oxidation

    SciTech Connect

    Pierce, R.A.

    1999-10-26

    Several non-thermal processes have been developed to destroy organic waste compounds using chemicals with high oxidation potentials. These efforts have focused on developing technologies that work at low temperatures, relative to incineration, to overcome many of the regulatory issues associated with obtaining permits for waste incinerators. One such technique with great flexibility is mixed acid oxidation. Mixed acid oxidation, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a non-volatile holding medium for the somewhat volatile oxidant. The combination of acids allows appreciable amounts of the concentrated oxidant to remain in the carrier acid well above the oxidant''s normal boiling point.

  19. Studies in zirconium oxidation

    NASA Technical Reports Server (NTRS)

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

    1968-01-01

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

  20. Congruently melting complex oxides

    SciTech Connect

    Abrahams, S.C.; Brandle, C.D. Jr.

    1988-04-26

    A device is described comprising: a material including a complex oxide, characterized in that the complex oxide is essentially free of gadolinium scandium gallium garnet, gadolinium gallium garnet and lithium niobate, and the composition of the complex oxide is congruent and differs from stoichiometry by at least 0.1 atomic percent for at least one constituent element.

  1. Rhodium oxides in unusual oxidation states

    NASA Astrophysics Data System (ADS)

    Reisner, Barbara Alice

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

  2. All-Oxide Photovoltaics.

    PubMed

    Rühle, Sven; Anderson, Assaf Y; Barad, Hannah-Noa; Kupfer, Benjamin; Bouhadana, Yaniv; Rosh-Hodesh, Eli; Zaban, Arie

    2012-12-20

    Recently, a new field in photovoltaics (PV) has emerged, focusing on solar cells that are entirely based on metal oxide semiconductors. The all-oxide PV approach is very attractive due to the chemical stability, nontoxicity, and abundance of many metal oxides that potentially allow manufacturing under ambient conditions. Already today, metal oxides (MOs) are widely used as components in PV cells such as transparent conducting front electrodes or electron-transport layers, while only very few MOs have been used as light absorbers. In this Perspective, we review recent developments of all-oxide PV systems, which until today were mostly based on Cu2O as an absorber. Furthermore, ferroelectric BiFeO3-based PV systems are discussed, which have recently attracted considerable attention. The performance of all-oxide PV cells is discussed in terms of general PV principles, and directions for progress are proposed, pointing toward the development of novel metal oxide semiconductors using combinatorial methods.

  3. Partial oxidation catalyst

    DOEpatents

    Krumpelt, Michael; Ahmed, Shabbir; Kumar, Romesh; Doshi, Rajiv

    2000-01-01

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

  4. 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.

  5. Zirconium Oxide Nanostructures Prepared by Anodic Oxidation

    SciTech Connect

    Dang, Ying Yi; Bhuiyan, Md S; Paranthaman, Mariappan Parans

    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 films 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 film to flake off. Further studies are needed to define the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  6. 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.

  7. Oxidation Resistant Graphite Studies

    SciTech Connect

    W. Windes; R. Smith

    2014-07-01

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

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

    DOEpatents

    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.

  9. Design for Oxidation Resistance

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  10. METAL OXIDE NANOPARTICLES

    SciTech Connect

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

    2007-10-01

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

  11. OXIDATION OF TRANSURANIC ELEMENTS

    DOEpatents

    Moore, R.L.

    1959-02-17

    A method is reported for oxidizing neptunium or plutonium in the presence of cerous values without also oxidizing the cerous values. The method consists in treating an aqueous 1N nitric acid solution, containing such cerous values together with the trivalent transuranic elements, with a quantity of hydrogen peroxide stoichiometrically sufficient to oxidize the transuranic values to the hexavalent state, and digesting the solution at room temperature.

  12. Multifunctional Oxide Heterostructures

    SciTech Connect

    Tsymbal, E Y; Dagotto, Elbio R; Eom, Professor Chang-Beom; Ramesh, Ramamoorthy

    2012-01-01

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

  13. Mixed oxide solid solutions

    DOEpatents

    Magno, Scott; Wang, Ruiping; Derouane, Eric

    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.

  14. 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.

  15. Pyrite oxidation by microbial consortia

    NASA Astrophysics Data System (ADS)

    Bostick, B. C.; Revill, K. L.; Doyle, C.; Kendelewicz, T.; Brown, G. E.; Spormann, A. M.; Fendorf, S.

    2003-12-01

    Acid mine drainage (AMD) is formed through pyrite oxidation, which produces acidity and releases toxic metals associated with pyrite and other sulfide minerals. Microbes accelerate pyrite oxidation markedly, thereby playing a major role in the production of AMD. Here, we probe pyrite oxidation by consortia of Thiobacillus ferrooxidans and thiooxidans using surface-sensitive photoelectron spectroscopy and X-ray absorption spectroscopy and compare them with surfaces oxidized through chemical and single species cultures. Microbial oxidation resulted in the formation of distinct oxidized surface species distributed non-uniformly over the pyrite surface; consortia produced a surface both more heterogeneous and more oxidized. In contrast, chemical oxidation proceeds without the build-up of passivating oxidation products. Surface morphology was not correlated with sites of nucleation or oxidation in any obvious manner. These results demonstrate that microbial oxidation occurs through a similar mechanism to chemical oxidation, but that the presence of complex microbial communities may impact the manner by which pyrite oxidation proceeds.

  16. Catalytic process for formaldehyde oxidation

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  17. Reducible oxide based catalysts

    DOEpatents

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

    2010-04-06

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

  18. 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

  19. PROCESS OF OXIDIZING PLUTONIUM

    DOEpatents

    Coryell, C.D.

    1959-08-25

    The oxidation of plutonium to the plus six valence state is described. The oxidation is accomplished by treating the plutonium in aqueous solution with a solution above 0.01 molar in argentic ion, above 1.1 molar in nitric acid, and above 0.02 molar in argentous ion.

  20. Stabilized chromium oxide film

    DOEpatents

    Garwin, Edward L.; Nyaiesh, Ali R.

    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.

  1. 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.

  2. Lagoons and Oxidation Ponds.

    ERIC Educational Resources Information Center

    O'Brien, W. J.

    1978-01-01

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

  3. Oxidation State 10 Exists.

    PubMed

    Yu, Haoyu S; Truhlar, Donald G

    2016-07-25

    In a recent paper, Wang et al. found an iridium-containing compound with a formal oxidation state of 9. This is the highest oxidation state ever found in a stable compound. To learn if this is the highest chemical oxidation state possible, Kohn-Sham density functional theory was used to study various compounds, including PdO4 (2+) , PtO4 (2+) , PtO3 F2 (2+) , PtO4 OH(+) , PtO5 , and PtO4 SH(+) , in which the metal has an oxidation state of 10. It was found that PtO4 (2+) has a metastable state that is kinetically stable with a barrier height for decomposition of 31 kcal mol(-1) and a calculated lifetime of 0.9 years. All other compounds studied would readily decompose to lower oxidation states.

  4. Organic Oxidations Using Geomimicry.

    PubMed

    Yang, Ziming; Hartnett, Hilairy E; Shock, Everett L; Gould, Ian R

    2015-12-18

    Oxidations of phenylacetic acid to benzaldehyde, benzyl alcohol to benzaldehyde, and benzaldehyde to benzoic acid have been observed, in water as the solvent and using only copper(II) chloride as the oxidant. The reactions are performed at 250 °C and 40 bar, conditions that mimic hydrothermal reactions that are geochemically relevant. Speciation calculations show that the oxidizing agent is not freely solvated copper(II) ions, but complexes of copper(II) with chloride and carboxylate anions. Measurements of the reaction stoichiometries and also of substituent effects on reactivity allow plausible mechanisms to be proposed. These oxidation reactions are relevant to green chemistry in that they proceed in high chemical yield in water as the solvent and avoid the use of toxic heavy metal oxidizing reagents. PMID:26561976

  5. Death from Nitrous Oxide.

    PubMed

    Bäckström, Björn; Johansson, Bengt; Eriksson, Anders

    2015-11-01

    Nitrous oxide is an inflammable gas that gives no smell or taste. It has a history of abuse as long as its clinical use, and deaths, although rare, have been reported. We describe two cases of accidental deaths related to voluntary inhalation of nitrous oxide, both found dead with a gas mask covering the face. In an attempt to find an explanation to why the victims did not react properly to oncoming hypoxia, we performed experiments where a test person was allowed to breath in a closed system, with or without nitrous oxide added. Vital signs and gas concentrations as well as subjective symptoms were recorded. The experiments indicated that the explanation to the fact that neither of the descendents had reacted to oncoming hypoxia and hypercapnia was due to the inhalation of nitrous oxide. This study raises the question whether nitrous oxide really should be easily, commercially available. PMID:26258592

  6. Oxidation characteristics of molybdenum-zirconium oxide cermets

    NASA Technical Reports Server (NTRS)

    Heitzinger, B.

    1984-01-01

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

  7. Biocompatibility of Graphene Oxide

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  8. Oxide Nanocrystal Model Catalysts.

    PubMed

    Huang, Weixin

    2016-03-15

    Model catalysts with uniform and well-defined surface structures have been extensively employed to explore structure-property relationships of powder catalysts. Traditional oxide model catalysts are based on oxide single crystals and single crystal thin films, and the surface chemistry and catalysis are studied under ultrahigh-vacuum conditions. However, the acquired fundamental understandings often suffer from the "materials gap" and "pressure gap" when they are extended to the real world of powder catalysts working at atmospheric or higher pressures. Recent advances in colloidal synthesis have realized controlled synthesis of catalytic oxide nanocrystals with uniform and well-defined morphologies. These oxide nanocrystals consist of a novel type of oxide model catalyst whose surface chemistry and catalysis can be studied under the same conditions as working oxide catalysts. In this Account, the emerging concept of oxide nanocrystal model catalysts is demonstrated using our investigations of surface chemistry and catalysis of uniform and well-defined cuprous oxide nanocrystals and ceria nanocrystals. Cu2O cubes enclosed with the {100} crystal planes, Cu2O octahedra enclosed with the {111} crystal planes, and Cu2O rhombic dodecahedra enclosed with the {110} crystal planes exhibit distinct morphology-dependent surface reactivities and catalytic properties that can be well correlated with the surface compositions and structures of exposed crystal planes. Among these types of Cu2O nanocrystals, the octahedra are most reactive and catalytically active due to the presence of coordination-unsaturated (1-fold-coordinated) Cu on the exposed {111} crystal planes. The crystal-plane-controlled surface restructuring and catalytic activity of Cu2O nanocrystals were observed in CO oxidation with excess oxygen. In the propylene oxidation reaction with O2, 1-fold-coordinated Cu on Cu2O(111), 3-fold-coordinated O on Cu2O(110), and 2-fold-coordinated O on Cu2O(100) were identified

  9. NEPTUNIUM OXIDE PROCESSING

    SciTech Connect

    Jordan, J; Watkins, R; Hensel, S

    2009-05-27

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

  10. All-Oxide Photovoltaics.

    PubMed

    Rühle, Sven; Anderson, Assaf Y; Barad, Hannah-Noa; Kupfer, Benjamin; Bouhadana, Yaniv; Rosh-Hodesh, Eli; Zaban, Arie

    2012-12-20

    Recently, a new field in photovoltaics (PV) has emerged, focusing on solar cells that are entirely based on metal oxide semiconductors. The all-oxide PV approach is very attractive due to the chemical stability, nontoxicity, and abundance of many metal oxides that potentially allow manufacturing under ambient conditions. Already today, metal oxides (MOs) are widely used as components in PV cells such as transparent conducting front electrodes or electron-transport layers, while only very few MOs have been used as light absorbers. In this Perspective, we review recent developments of all-oxide PV systems, which until today were mostly based on Cu2O as an absorber. Furthermore, ferroelectric BiFeO3-based PV systems are discussed, which have recently attracted considerable attention. The performance of all-oxide PV cells is discussed in terms of general PV principles, and directions for progress are proposed, pointing toward the development of novel metal oxide semiconductors using combinatorial methods. PMID:26291107

  11. Highly oxidized graphene oxide and methods for production thereof

    DOEpatents

    Tour, James M.; Kosynkin, Dmitry V.

    2016-08-30

    A highly oxidized form of graphene oxide and methods for production thereof are described in various embodiments of the present disclosure. In general, the methods include mixing a graphite source with a solution containing at least one oxidant and at least one protecting agent and then oxidizing the graphite source with the at least one oxidant in the presence of the at least one protecting agent to form the graphene oxide. Graphene oxide synthesized by the presently described methods is of a high structural quality that is more oxidized and maintains a higher proportion of aromatic rings and aromatic domains than does graphene oxide prepared in the absence of at least one protecting agent. Methods for reduction of graphene oxide into chemically converted graphene are also disclosed herein. The chemically converted graphene of the present disclosure is significantly more electrically conductive than is chemically converted graphene prepared from other sources of graphene oxide.

  12. Acute in vivo toxicity mitigation of PEI-coated maghemite nanoparticles using controlled oxidation and surface modifications toward siRNA delivery.

    PubMed

    Israel, Liron Limor; Lellouche, Emmanuel; Ostrovsky, Stella; Yarmiayev, Valeria; Bechor, Moshe; Michaeli, Shulamit; Lellouche, Jean-Paul Moshe

    2015-07-22

    A ceric ammonium nitrate (CAN)-based doping step was used for the fabrication of core maghemite nanoparticles (NPs) that enabled the obtainment of colloid particles with a view to a high-level nanoparticle (NP) surface doping by Ce(III/IV). Such doping of Ce(III/IV) cations enables one to exploit their quite rich coordination chemistry for ligand coordinative binding. In fact, they were shown to act as powerful Lewis acid centers for attaching any organic (Lewis base) ligand such as a 25 kDa branched PEI polymer. Resulting conPEI25-CAN-γ-Fe2O3 NPs have been fully characterized before a successful implementation of siRNA loading and cell delivery/gene silencing using a well-known dual luciferase system. This attractive result emphasized their significant potential as an NP platform technology toward additional MRI and/or drug delivery (peptide)-relating end applications. However, due to their high positive charge, PEI polymers can cause severe in vivo toxicity due to their interaction with negatively charged red blood cells (RBC), resulting in RBC aggregation and lysis, leading to thrombosis and, finally, to animal death. In order to mitigate these acute toxic effects, two different types of surface modifications were performed. One modification included the controlled oxidation of 0.1-5% of the PEI amines before or after conjugation to the NPs, using hydrogen peroxide or potassium persulfate. The other type of modification was the addition of a second biocompatible polyanionic polymer to the PEI grafted NPs, based on the concept of a layer-by-layer (LbL) technique. This modification is based on the coordination of another polyanionic polymer on the NPs surface in order to create a combined hybrid PEI and polyanionic polymer nanosystem. In both cases, the surface modification successfully mitigated the NP acute in vivo toxicity, without compromising the silencing efficiency. PMID:26120905

  13. Viscoelastic characterization and modeling of gelation kinetics of injectable in situ cross-linkable poly(lactide-co-ethylene oxide-co-fumarate) hydrogels.

    PubMed

    Sarvestani, Alireza S; He, Xuezhong; Jabbari, Esmaiel

    2007-02-01

    Cell transplantation by injection of biodegradable hydrogels is a recently developed strategy for the treatment of degenerated tissues. A cell carrier should be cytocompatible, have suitable working time and rheological properties for injection, and harden in situ to attain dimensional stability and the desired mechanical strength. Hydrophilic macromer/cross-linker polymerizing systems, due to the relatively high molecular weight of the macromer and its inability to cross the cell membrane, are very attractive as injectable cell carriers. The objective of this research was to determine the effects of cross-linker, initiator, and accelerator concentrations on the gelation kinetics and ultimate modulus of a biodegradable, in situ cross-linkable poly(lactide-co-ethylene oxide-co-fumarate) (PLEOF) macromer. The in situ polymerizing mixture consisted of PLEOF macromer, methylene bisacrylamide cross-linker, and a neutral redox initiation system of ammonium persulfate initiator and tetramethylethylenediamine accelerator. Measurement of the time evolution of the viscoelastic properties of the network during the sol-gel transition showed the important influence of each component on the gel time and stiffness of the hydrogels. A kinetic model was developed to predict the modulus as a function of composition. Model predictions were consistent with most of the experimental findings. The values of the storage and loss moduli at the gel point were found to be approximately equal for samples with equal PLEOF concentrations, resulting in a simple method to predict the gelation time based on the Winter--Chambon criterion, with the use of the proposed kinetic model. The results of this study can be coupled with component cytocompatibility measurements to predict the effect of composition on the viability of the cells encapsulated in the hydrogel matrix. PMID:17253761

  14. Oxidative Tritium Decontamination System

    DOEpatents

    Gentile, Charles A. , Guttadora, Gregory L. , Parker, John J.

    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.

  15. Today's oxidative stress markers.

    PubMed

    Czerska, Marta; Mikołajewska, Karolina; Zieliński, Marek; Gromadzińska, Jolanta; Wąsowicz, Wojciech

    2015-01-01

    Oxidative stress represents a situation where there is an imbalance between the reactive oxygen species (ROS) and the availability and the activity of antioxidants. This balance is disturbed by increased generation of free radicals or decreased antioxidant activity. It is very important to develop methods and find appropriate biomarkers that may be used to assess oxidative stress in vivo. It is significant because appropriate measurement of such stress is necessary in identifying its role in lifestyle-related diseases. Previously used markers of oxidative stress, such as thiobarbituric acid reactive substances (TBARS) or malondialdehyde (MDA), are progressively being supplemented by new ones, such as isoprostanes (IsoPs) and their metabolites or allantoin. This paper is focusing on the presentation of new ones, promising markers of oxidative stress (IsoPs, their metabolites and allantoin), taking into account the advantage of those markers over markers used previously. PMID:26325052

  16. 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.

  17. Mercuric oxide poisoning

    MedlinePlus

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

  18. 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.

  19. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

  20. Metal atom oxidation laser

    DOEpatents

    Jensen, R.J.; Rice, W.W.; Beattie, W.H.

    1975-10-28

    A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

  1. 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.

  2. 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.…

  3. 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

  4. Staphylococcal response to oxidative stress

    PubMed Central

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

    2012-01-01

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

  5. Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress.

    PubMed

    Liu, Shaobin; Zeng, Tingying Helen; Hofmann, Mario; Burcombe, Ehdi; Wei, Jun; Jiang, Rongrong; Kong, Jing; Chen, Yuan

    2011-09-27

    Health and environmental impacts of graphene-based materials need to be thoroughly evaluated before their potential applications. Graphene has strong cytotoxicity toward bacteria. To better understand its antimicrobial mechanism, we compared the antibacterial activity of four types of graphene-based materials (graphite (Gt), graphite oxide (GtO), graphene oxide (GO), and reduced graphene oxide (rGO)) toward a bacterial model-Escherichia coli. Under similar concentration and incubation conditions, GO dispersion shows the highest antibacterial activity, sequentially followed by rGO, Gt, and GtO. Scanning electron microscope (SEM) and dynamic light scattering analyses show that GO aggregates have the smallest average size among the four types of materials. SEM images display that the direct contacts with graphene nanosheets disrupt cell membrane. No superoxide anion (O(2)(•-)) induced reactive oxygen species (ROS) production is detected. However, the four types of materials can oxidize glutathione, which serves as redox state mediator in bacteria. Conductive rGO and Gt have higher oxidation capacities than insulating GO and GtO. Results suggest that antimicrobial actions are contributed by both membrane and oxidation stress. We propose that a three-step antimicrobial mechanism, previously used for carbon nanotubes, is applicable to graphene-based materials. It includes initial cell deposition on graphene-based materials, membrane stress caused by direct contact with sharp nanosheets, and the ensuing superoxide anion-independent oxidation. We envision that physicochemical properties of graphene-based materials, such as density of functional groups, size, and conductivity, can be precisely tailored to either reducing their health and environmental risks or increasing their application potentials.

  6. 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.

  7. 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.

  8. 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.

  9. Mesoporous gallium oxide structurally stabilized by yttrium oxide

    SciTech Connect

    Yada, Mitsunori; Ohya, Masahumi; Machida, Masato; Kijima, Tsuyoshi

    2000-05-16

    Since the synthesis of mesoporous silicas such as MCM-41 and FSM-16 with large internal surface areas and uniform pore sizes, the surfactant templating method has been used to synthesize mesoporous metal oxides, including titanium, aluminum, niobium, and tantalum oxides. The mesostructured metal oxides are taken to be useful not only as catalysts and separating or adsorbing agents but also as functional host materials with optically, electrically, or magnetically unique properties, owing to the shape-specific and/or quantum effects of their thin inorganic skeletons. Mesoporous zirconium oxide and phosphate and hafnium oxide are promising as acid catalysts. Layered and hexagonal mesostructured titanium oxides, for example, were observed to be photocatalytically active. Aluminum and gallium oxides with a mesoporous structure are also expected to serve as a catalytic of other functional material. In this paper, the authors report the synthesis and characterization of mesoporous gallium oxide stabilized by yttrium oxide.

  10. Switching Oxide Traps

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.

    2003-01-01

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

  11. Nonaqueous Catalytic Water Oxidation

    SciTech Connect

    Chen, Zuofeng; Concepcion, Javier J.; Luo, Hanlin; Hull, Jonathan F.; Paul, Amit; Meyer, Thomas J.

    2010-11-23

    The complex [Ru(Mebimpy)(bpy)(OH2)]2+ [Mebimpy = 2,6-bis(1-methylbenzimidazol-2-yl)pyridine; bpy = 2,2'-bipyridine] and its 4,4'-(PO3H2CH2)2bpy derivative on oxide electrodes are water oxidation catalysts in propylene carbonate and 2,2,2-trifluoroethanol (TFE) to which water has been added as a limiting reagent. The rate of water oxidation is greatly enhanced relative to that with water as the solvent and occurs by a pathway that is first-order in H2O; an additional pathway that is first-order in acetate appears when TFE is used as the solvent.

  12. 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.

  13. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    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.

  14. Methanol partial oxidation reformer

    DOEpatents

    Ahmed, Shabbir; Kumar, Romesh; Krumpelt, Michael

    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.

  15. 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.

  16. Oxidative Tritium Decontamination System

    SciTech Connect

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

    2002-02-11

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

  17. Oxidative folding: recent developments.

    PubMed

    Szarka, András; Bánhegyi, Gábor

    2011-10-01

    Disulfide bond formation in proteins is an effective tool of both structure stabilization and redox regulation. The prokaryotic periplasm and the endoplasmic reticulum of eukaryotes were long considered as the only compartments for enzyme mediated formation of stable disulfide bonds. Recently, the mitochondrial intermembrane space has emerged as the third protein-oxidizing compartment. The classic view on the mechanism of oxidative folding in the endoplasmic reticulum has also been reshaped by new observations. Moreover, besides the structure stabilizing function, reversible disulfide bridge formation in some proteins of the endoplasmic reticulum, seems to play a regulatory role. This review briefly summarizes the present knowledge of the redox systems supporting oxidative folding, emphasizing recent developments. PMID:25962043

  18. Microbial Formaldehyde Oxidation

    SciTech Connect

    Timothy J. Donohue

    2004-12-09

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

  19. Krypton oxides under pressure

    PubMed Central

    Zaleski-Ejgierd, Patryk; Lata, Pawel M.

    2016-01-01

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds. PMID:26830129

  20. Tetraalklylammonium polyoxoanionic oxidation catalysts

    DOEpatents

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

    1998-10-06

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

  1. Tetraalykylammonium polyoxoanionic oxidation catalysts

    DOEpatents

    Ellis, Paul E.; Lyons, James E.; Myers, Jr., Harry K.; Shaikh, Shahid N.

    1998-01-01

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

  2. Krypton oxides under pressure.

    PubMed

    Zaleski-Ejgierd, Patryk; Lata, Pawel M

    2016-02-02

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds.

  3. Molecular water oxidation catalyst

    DOEpatents

    Gratzel, Michael; Munavalli, Shekhar; Pern, Fu-Jann; Frank, Arthur J.

    1993-01-01

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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  6. Krypton oxides under pressure.

    PubMed

    Zaleski-Ejgierd, Patryk; Lata, Pawel M

    2016-01-01

    Under high pressure, krypton, one of the most inert elements is predicted to become sufficiently reactive to form a new class of krypton compounds; krypton oxides. Using modern ab-initio evolutionary algorithms in combination with Density Functional Theory, we predict the existence of several thermodynamically stable Kr/O species at elevated pressures. In particular, our calculations indicate that at approx. 300 GPa the monoxide, KrO, should form spontaneously and remain thermo- and dynamically stable with respect to constituent elements and higher oxides. The monoxide is predicted to form non-molecular crystals with short Kr-O contacts, typical for genuine chemical bonds. PMID:26830129

  7. Simulation and comparative study on the oxidation kinetics of atrazine by UV/H₂O₂, UV/HSO₅⁻ and UV/S₂O₈²⁻.

    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 (k(app), 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 k(app) 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 k(app) 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

  8. Simulation and comparative study on the oxidation kinetics of atrazine by UV/H₂O₂, UV/HSO₅⁻ and UV/S₂O₈²⁻.

    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 (k(app), 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 k(app) 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 k(app) 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

  9. Low temperature oxidation of plutonium

    SciTech Connect

    Nelson, Art J.; Roussel, Paul

    2013-05-15

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

  10. Uranium oxidation: characterization of oxides formed by reaction with water

    SciTech Connect

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

    1983-04-27

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

  11. Conformations of organophosphine oxides

    SciTech Connect

    De Silva, Nuwan; Zahariev, Federico; Hay, Benjamin P.; Gordon, Mark S.; Windus, Theresa L.

    2015-07-17

    The conformations of a series of organophosphine oxides, OP(CH3)2R, where R = methyl, ethyl, isopropyl, tert-butyl, vinyl, and phenyl, are predicted using the MP2/cc-pVTZ level of theory. Comparison of potential energy surfaces for rotation about P–C bonds with crystal structure data reveals a strong correlation between predicted location and energetics of minima and histograms of dihedral angle distributions observed in the solid state. In addition, the most stable conformers are those that minimize the extent of steric repulsion between adjacent rotor substituents, and the torsional barriers tend to increase with the steric bulk of the rotating alkyl group. MM3 force field parameters were adjusted to fit the MP2 results, providing a fast and accurate model for predicting organophosphine oxides shapes—an essential part of understanding the chemistry of these compounds. As a result, the predictive power of the modified MM3 model was tested against MP2/cc-pVTZ conformations for triethylphosphine oxide, OP(CH2CH3)3, and triphenylphosphine oxide, OP(Ph)3.

  12. Water oxidation: Intermediate identification

    NASA Astrophysics Data System (ADS)

    Cowan, Alexander J.

    2016-08-01

    The slow kinetics of light-driven water oxidation on haematite is an important factor limiting the material's efficiency. Now, an intermediate of the water-splitting reaction has been identified offering hope that the full mechanism will soon be resolved.

  13. Tributyltin oxide (TBTO)

    Integrated Risk Information System (IRIS)

    Tributyltin oxide ( TBTO ) ; CASRN 56 - 35 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarc

  14. Highly oxidized superconductors

    DOEpatents

    Morris, Donald E.

    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.

  15. Highly oxidized superconductors

    DOEpatents

    Morris, D.E.

    1994-09-20

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

  16. Conformations of organophosphine oxides

    DOE PAGES

    De Silva, Nuwan; Zahariev, Federico; Hay, Benjamin P.; Gordon, Mark S.; Windus, Theresa L.

    2015-07-17

    The conformations of a series of organophosphine oxides, OP(CH3)2R, where R = methyl, ethyl, isopropyl, tert-butyl, vinyl, and phenyl, are predicted using the MP2/cc-pVTZ level of theory. Comparison of potential energy surfaces for rotation about P–C bonds with crystal structure data reveals a strong correlation between predicted location and energetics of minima and histograms of dihedral angle distributions observed in the solid state. In addition, the most stable conformers are those that minimize the extent of steric repulsion between adjacent rotor substituents, and the torsional barriers tend to increase with the steric bulk of the rotating alkyl group. MM3 forcemore » field parameters were adjusted to fit the MP2 results, providing a fast and accurate model for predicting organophosphine oxides shapes—an essential part of understanding the chemistry of these compounds. As a result, the predictive power of the modified MM3 model was tested against MP2/cc-pVTZ conformations for triethylphosphine oxide, OP(CH2CH3)3, and triphenylphosphine oxide, OP(Ph)3.« less

  17. Doped zinc oxide microspheres

    DOEpatents

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

    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.

  18. 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.

  19. 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

  20. 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.

  1. Oxide charge accumulation in metal oxide semiconductor devices during irradiation

    SciTech Connect

    Lee, D. ); Chan, C. )

    1991-05-15

    An analysis of a simple physical model for radiation induced oxide charge accumulation in the SiO{sub 2} layer of metal oxide semiconductor (MOS) structure has been developed. The model assumes that both electron and hole traps exist in the oxide layer. These traps can capture electrons as well as holes during irradiation. Using this model, final oxide charge distributions in the oxide layer of MOS capacitors exposed to a total dose radiation can be predicted. The resulting charge distribution is calculated to yield the midgap voltage shifts as functions of total dose, bias voltage, and oxide thickness. The results are shown to agree well with the experimental data. Furthermore, the model successfully analyzes the radiation-induced negative oxide charge distribution in an ion-implanted, radiation-hard MOS capacitor. These negative oxide charge distributions not only partially compensate the effects of trapped positive oxide charges but also reduced the density of positive oxide charges trapped near the Si/SiO{sub 2} interface. We found the reduction of the positive oxide charge density near the Si/SiO{sub 2} interface is due to internal electric field modification in the oxide layer.

  2. 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.

  3. Protein oxidation and peroxidation.

    PubMed

    Davies, Michael J

    2016-04-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established.

  4. Protein oxidation and peroxidation

    PubMed Central

    Davies, Michael J.

    2016-01-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals and chain reactions with alcohols and carbonyls as major products; the latter are commonly used markers of protein damage. Direct oxidation of cysteine (and less commonly) methionine residues is a major reaction; this is typically faster than with H2O2, and results in altered protein activity and function. Unlike H2O2, which is rapidly removed by protective enzymes, protein peroxides are only slowly removed, and catabolism is a major fate. Although turnover of modified proteins by proteasomal and lysosomal enzymes, and other proteases (e.g. mitochondrial Lon), can be efficient, protein hydroperoxides inhibit these pathways and this may contribute to the accumulation of modified proteins in cells. Available evidence supports an association between protein oxidation and multiple human pathologies, but whether this link is causal remains to be established. PMID:27026395

  5. 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

  6. Experiments with Unusual Oxidation States

    ERIC Educational Resources Information Center

    Kauffman, G. B.

    1975-01-01

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

  7. Staged membrane oxidation reactor system

    SciTech Connect

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

    2013-04-16

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

  8. Staged membrane oxidation reactor system

    SciTech Connect

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

    2014-05-20

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

  9. Staged membrane oxidation reactor system

    DOEpatents

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

    2012-09-11

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

  10. Oxygen sensitive, refractory oxide composition

    DOEpatents

    Holcombe, Jr., Cressie E.; Smith, Douglas D.

    1976-01-01

    Oxide compositions containing niobium pentoxide and an oxide selected from the group consisting of hafnia, titania, and zirconia have electrical conductivity characteristics which vary greatly depending on the oxygen content.

  11. REVIEW OF PLUTONIUM OXIDATION LITERATURE

    SciTech Connect

    Korinko, P.

    2009-11-12

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

  12. Nitric oxide scavengers differentially inhibit ammonia oxidation in ammonia-oxidizing archaea and bacteria.

    PubMed

    Sauder, Laura A; Ross, Ashley A; Neufeld, Josh D

    2016-04-01

    Differential inhibitors are important for measuring the relative contributions of microbial groups, such as ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), to biogeochemical processes in environmental samples. In particular, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) represents a nitric oxide scavenger used for the specific inhibition of AOA, implicating nitric oxide as an intermediate of thaumarchaeotal ammonia oxidation. This study investigated four alternative nitric oxide scavengers for their ability to differentially inhibit AOA and AOB in comparison to PTIO. Caffeic acid, curcumin, methylene blue hydrate and trolox were tested onNitrosopumilus maritimus, two unpublished AOA representatives (AOA-6f and AOA-G6) as well as the AOB representative Nitrosomonas europaea All four scavengers inhibited ammonia oxidation by AOA at lower concentrations than for AOB. In particular, differential inhibition of AOA and AOB by caffeic acid (100 μM) and methylene blue hydrate (3 μM) was comparable to carboxy-PTIO (100 μM) in pure and enrichment culture incubations. However, when added to aquarium sponge biofilm microcosms, both scavengers were unable to inhibit ammonia oxidation consistently, likely due to degradation of the inhibitors themselves. This study provides evidence that a variety of nitric oxide scavengers result in differential inhibition of ammonia oxidation in AOA and AOB, and provides support to the proposed role of nitric oxide as a key intermediate in the thaumarchaeotal ammonia oxidation pathway.

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

    SciTech Connect

    Wang Gongkai; Sun Xiang; Lian Jie; Liu Changsheng

    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.

  14. Doped palladium containing oxidation catalysts

    DOEpatents

    Mohajeri, Nahid

    2014-02-18

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

  15. Catalytic oxidation of dimethyl ether

    DOEpatents

    Zelenay, Piotr; Wu, Gang; Johnston, Christina M.; Li, Qing

    2016-05-10

    A composition for oxidizing dimethyl ether includes an alloy supported on carbon, the alloy being of platinum, ruthenium, and palladium. A process for oxidizing dimethyl ether involves exposing dimethyl ether to a carbon-supported alloy of platinum, ruthenium, and palladium under conditions sufficient to electrochemically oxidize the dimethyl ether.

  16. Model catalytic oxidation studies using supported monometallic and heterobimetallic oxides

    SciTech Connect

    Ekerdt, J.G.

    1992-02-03

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

  17. Iron oxide surfaces

    NASA Astrophysics Data System (ADS)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  18. Intrinsic anion oxidation potentials.

    PubMed

    Johansson, Patrik

    2006-11-01

    Anions of lithium battery salts have been investigated by electronic structure calculations with the objective to find a computational measure to correlate with the observed (in)stability of nonaqueous lithium battery electrolytes vs oxidation often encountered in practice. Accurate prediction of intrinsic anion oxidation potentials is here made possible by computing the vertical free energy difference between anion and neutral radical (Delta Gv) and further strengthened by an empirical correction using only the anion volume as a parameter. The 6-311+G(2df,p) basis set, the VSXC functional, and the C-PCM SCRF algorithm were used. The Delta Gv calculations can be performed using any standard computational chemistry software. PMID:17078600

  19. Entropy-stabilized oxides

    PubMed Central

    Rost, Christina M.; Sachet, Edward; Borman, Trent; Moballegh, Ali; Dickey, Elizabeth C.; Hou, Dong; Jones, Jacob L.; Curtarolo, Stefano; Maria, Jon-Paul

    2015-01-01

    Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, a simple thermodynamic model, and a five-component oxide formulation, we demonstrate beyond reasonable doubt that entropy predominates the thermodynamic landscape, and drives a reversible solid-state transformation between a multiphase and single-phase state. In the latter, cation distributions are proven to be random and homogeneous. The findings validate the hypothesis that deliberate configurational disorder provides an orthogonal strategy to imagine and discover new phases of crystalline matter and untapped opportunities for property engineering. PMID:26415623

  20. Cutaneous oxidative stress.

    PubMed

    Polefka, Thomas G; Meyer, Thomas A; Agin, Patricia P; Bianchini, Robert J

    2012-03-01

    The earliest known microfossil records suggest that microorganisms existed on the earth approximately 3.8 billion years ago. Not only did sunlight drive this evolutionary process, but it also allowed photosynthetic organisms to elaborate oxygen and fundamentally change the earth's atmosphere and subsequent evolution. Paradoxically, however, an atmosphere of 20% oxygen offers aerobic organisms both benefits and some key challenges, particularly, to the external integument. This mini-review summarizes almost 40 years of research and provides a "60 000-foot" perspective on cutaneous oxidative stress. Topics reviewed include the following: What are free radicals and reactive oxygen species? Where do they come from? What is their chemistry? What are their roles and/or impact on the skin? What antioxidant defenses are available to mitigate oxidative stress. PMID:22360336

  1. Enzymatic Oxidation of Methane

    SciTech Connect

    Sirajuddin, S; Rosenzweig, AC

    2015-04-14

    Methane monooxygenases (MMOs) are enzymes that catalyze the oxidation of methane to methanol in methanotrophic bacteria. As potential targets for new gas-to-liquid methane bioconversion processes, MMOs have attracted intense attention in recent years. There are two distinct types of MMO, a soluble, cytoplasmic MMO (sMMO) and a membrane-bound, particulate MMO (pMMO). Both oxidize methane at metal centers within a complex, multisubunit scaffold, but the structures, active sites, and chemical mechanisms are completely different. This Current Topic review article focuses on the overall architectures, active site structures, substrate reactivities, proteinprotein interactions, and chemical mechanisms of both MMOs, with an emphasis on fundamental aspects. In addition, recent advances, including new details of interactions between the sMMO components, characterization of sMMO intermediates, and progress toward understanding the pMMO metal centers are highlighted. The work summarized here provides a guide for those interested in exploiting MMOs for biotechnological applications.

  2. Controlled CO preferential oxidation

    DOEpatents

    Meltser, Mark A.; Hoch, Martin M.

    1997-01-01

    Method for controlling the supply of air to a PROX reactor for the preferential oxidation in the presence of hydrogen wherein the concentration of the hydrogen entering and exiting the PROX reactor is monitored, the difference therebetween correlated to the amount of air needed to minimize such difference, and based thereon the air supply to the PROX reactor adjusted to provide such amount and minimize such difference.

  3. 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

  4. Oxidation, Reduction, and Deoxygenation

    NASA Astrophysics Data System (ADS)

    Madsen, Robert

    In this chapter, methods for oxidation, reduction, and deoxygenation of carbohydrates are presented. In most cases, the reactions have been used on aldoses and their derivatives including glycosides, uronic acids, glycals, and other unsaturated monosaccharides. A number of reactions have also been applied to aldonolactones. The methods include both chemical and enzymatic procedures and some of these can be applied for regioselective transformation of unprotected or partially protected carbohydrates.

  5. Oxidation in a temperature gradient

    SciTech Connect

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

    2001-01-01

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

  6. Nonisostructural complex oxide heteroepitaxy

    SciTech Connect

    Wong, Franklin J. Ramanathan, Shriram

    2014-07-01

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

  7. Serum chemotactic inhibitory activity: heat activation of chemotactic inhibition.

    PubMed Central

    Epps, D E; Williams, R C

    1976-01-01

    Serum chemotactic inhibitory activity (CIA) was studied in 46 patients with various systemic diseases, using a system consisting of normal human leukocytes as indicator cells and 10% fresh normal serum as a control chemotactic attractant. It was shown, as previously reported, that an association exists between CIA and skin test anergy. Heat treatment of sera at 56 C for 30 min increased both the incidence and the degree of chemotactic inhibition observed in these patients. The effects of heat treatment of sera containing CIA on other chemotactic attractants (C3a, bacteria-derived chemotactic factor (BF), and casein) are shown. Before heat treatment, some sera suppressed chemotaxis mediated by BF in the absence of suppression of normal serum-mediated chemotaxis, indicating the possible involvement of more than one system of inhibition. Multiple systems were further supported by data indicating that room temperature incubation resulted in a loss of CIA as measured by normal serum-mediated chemotoxis with no apparent decrease in the inhibition of BF -mediated chemotaxis. Separation of sera containing CIA by Sephadex G-200 showed chemotactic inhibitory activity to be increased in both the void volume region. Experiments showed that heat treating before separation resulted in similar increases in both peaks, implying the presence of an antagonist to CIA. Experiments demonstrating that sera containing CIA do not suppress casein-mediated chemotaxis by means of an irreversible inactivation of chemotactic factor are included along with experiments demonstrating a cellular mode of action. The possible presence of two systems of chemotactic inhibition, one acting directly upon chemotactic factors and one interacting with the responding cell, are discussed. PMID:773824

  8. Lipid oxidation induced oxidative degradation of cereal beta-glucan.

    PubMed

    Wang, Yu-Jie; Mäkelä, Noora; Maina, Ndegwa Henry; Lampi, Anna-Maija; Sontag-Strohm, Tuula

    2016-04-15

    In food systems, lipid oxidation can cause oxidation of other molecules. This research for the first time investigated oxidative degradation of β-glucan induced by lipid oxidation using an oil-in-water emulsion system which simulated a multi-phased aqueous food system containing oil and β-glucan. Lipid oxidation was monitored using peroxide value and hexanal production while β-glucan degradation was evaluated by viscosity and molecular weight measurements. The study showed that while lipid oxidation proceeded, β-glucan degradation occurred. Emulsions containing β-glucan, oil and ferrous ion showed significant viscosity and molecular weight decrease after 1 week of oxidation at room temperature. Elevated temperature (40°C) enhanced the oxidation reactions causing higher viscosity drop. In addition, the presence of β-glucan appeared to retard the hexanal production in lipid oxidation. The study revealed that lipid oxidation may induce the degradation of β-glucan in aqueous food systems where β-glucan and lipids co-exist.

  9. Oxidative stress by inorganic nanoparticles.

    PubMed

    Tee, Jie Kai; Ong, Choon Nam; Bay, Boon Huat; Ho, Han Kiat; Leong, David Tai

    2016-05-01

    Metallic and metallic oxide nanoparticles (NPs) have been increasingly used for various bio-applications owing to their unique physiochemical properties in terms of conductivity, optical sensitivity, and reactivity. With the extensive usage of NPs, increased human exposure may cause oxidative stress and lead to undesirable health consequences. To date, various endogenous and exogenous sources of oxidants contributing to oxidative stress have been widely reported. Oxidative stress is generally defined as an imbalance between the production of oxidants and the activity of antioxidants, but it is often misrepresented as a single type of cellular stress. At the biological level, NPs can initiate oxidative stress directly or indirectly through various mechanisms, leading to profound effects ranging from the molecular to the disease level. Such effects of oxidative stress have been implicated owing to their small size and high biopersistence. On the other hand, cellular antioxidants help to counteract oxidative stress and protect the cells from further damage. While oxidative stress is commonly known to exert negative biological effects, measured and intentional use of NPs to induce oxidative stress may provide desirable effects to either stimulate cell growth or promote cell death. Hence, NP-induced oxidative stress can be viewed from a wide paradigm. Because oxidative stress is comprised of a wide array of factors, it is also important to use appropriate assays and methods to detect different pro-oxidant and antioxidant species at molecular and disease levels. WIREs Nanomed Nanobiotechnol 2016, 8:414-438. doi: 10.1002/wnan.1374 For further resources related to this article, please visit the WIREs website.

  10. Oxidative stress by inorganic nanoparticles.

    PubMed

    Tee, Jie Kai; Ong, Choon Nam; Bay, Boon Huat; Ho, Han Kiat; Leong, David Tai

    2016-05-01

    Metallic and metallic oxide nanoparticles (NPs) have been increasingly used for various bio-applications owing to their unique physiochemical properties in terms of conductivity, optical sensitivity, and reactivity. With the extensive usage of NPs, increased human exposure may cause oxidative stress and lead to undesirable health consequences. To date, various endogenous and exogenous sources of oxidants contributing to oxidative stress have been widely reported. Oxidative stress is generally defined as an imbalance between the production of oxidants and the activity of antioxidants, but it is often misrepresented as a single type of cellular stress. At the biological level, NPs can initiate oxidative stress directly or indirectly through various mechanisms, leading to profound effects ranging from the molecular to the disease level. Such effects of oxidative stress have been implicated owing to their small size and high biopersistence. On the other hand, cellular antioxidants help to counteract oxidative stress and protect the cells from further damage. While oxidative stress is commonly known to exert negative biological effects, measured and intentional use of NPs to induce oxidative stress may provide desirable effects to either stimulate cell growth or promote cell death. Hence, NP-induced oxidative stress can be viewed from a wide paradigm. Because oxidative stress is comprised of a wide array of factors, it is also important to use appropriate assays and methods to detect different pro-oxidant and antioxidant species at molecular and disease levels. WIREs Nanomed Nanobiotechnol 2016, 8:414-438. doi: 10.1002/wnan.1374 For further resources related to this article, please visit the WIREs website. PMID:26359790

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

    SciTech Connect

    Särhammar, Erik Berg, Sören; Nyberg, Tomas

    2014-07-01

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

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

    SciTech Connect

    Vogt, Patrick; Bierwagen, Oliver

    2015-02-23

    The hetero-epitaxial growth of the n-type semiconducting oxides β-Ga{sub 2}O{sub 3}, In{sub 2}O{sub 3}, and SnO{sub 2} on c- and r-plane sapphire was performed by plasma-assisted molecular beam epitaxy. The growth-rate and desorbing flux from the substrate were measured in-situ under various oxygen to metal ratios by laser reflectometry and quadrupole mass spectrometry, respectively. These measurements clarified the role of volatile sub-oxide formation (Ga{sub 2}O, In{sub 2}O, and SnO) during growth, the sub-oxide stoichiometry, and the efficiency of oxide formation for the three oxides. As a result, the formation of the sub-oxides decreased the growth-rate under metal-rich growth conditions and resulted in etching of the oxide film by supplying only metal flux. The flux ratio for the exclusive formation of the sub-oxide (e.g., the p-type semiconductor SnO) was determined, and the efficiency of oxide formation was found to be the highest for SnO{sub 2}, somewhat lower for In{sub 2}O{sub 3}, and the lowest for Ga{sub 2}O{sub 3}. Our findings can be generalized to further oxides that possess related sub-oxides.

  13. Iron oxide surfaces

    NASA Astrophysics Data System (ADS)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  14. Oxidative stress and oxidative damage in chemical carcinogenesis

    SciTech Connect

    Klaunig, James E. 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.

  15. Iridium oxide-polymer nanocomposite electrode materials for water oxidation.

    PubMed

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

    2014-08-13

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

  16. The oxidative hypothesis of senescence.

    PubMed

    Gilca, M; Stoian, I; Atanasiu, V; Virgolici, B

    2007-01-01

    The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g, those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc). This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal beta -oxidation and respiratory burst of phagocytic cells), antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol), alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  17. Oxidative Denitrogenation of Coal Liquids

    NASA Astrophysics Data System (ADS)

    Mirshamsi, Sepideh

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

  18. Arsenic doped zinc oxide

    SciTech Connect

    Volbers, N.; Lautenschlaeger, S.; Leichtweiss, T.; Laufer, A.; Graubner, S.; Meyer, B. K.; Potzger, K.; Zhou Shengqiang

    2008-06-15

    As-doping of zinc oxide has been approached by ion implantation and chemical vapor deposition. The effect of thermal annealing on the implanted samples has been investigated by using secondary ion mass spectrometry and Rutherford backscattering/channeling geometry. The crystal damage, the distribution of the arsenic, the diffusion of impurities, and the formation of secondary phases is discussed. For the thin films grown by vapor deposition, the composition has been determined with regard to the growth parameters. The bonding state of arsenic was investigated for both series of samples using x-ray photoelectron spectroscopy.

  19. Zinc Oxide Nanophotonics

    NASA Astrophysics Data System (ADS)

    Choi, Sumin; Aharonovich, Igor

    2015-12-01

    The emerging field of nanophotonics initiated a dedicated study of single photon sources and optical resonators in new class of materials. One such material is zinc oxide (ZnO) that has been long considered only for classical light-emitting applications. However, it recently showed promise for quantum photonics technologies. In this review, we highlight the recent advances in studying single emitters in ZnO, engineering of optical cavities and practical nanophotonics devices including nanolasers and electrically triggered devices. We finalize with an outlook at this promising area, as well as provide perspectives and open questions in solid state nanophotonics employing ZnO.

  20. Electrolytic oxide reduction system

    DOEpatents

    Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L; Berger, John F

    2015-04-28

    An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies, a plurality of cathode assemblies, and a lift system configured to engage the anode and cathode assemblies. The cathode assemblies may be alternately arranged with the anode assemblies such that each cathode assembly is flanked by two anode assemblies. The lift system may be configured to selectively engage the anode and cathode assemblies so as to allow the simultaneous lifting of any combination of the anode and cathode assemblies (whether adjacent or non-adjacent).

  1. PLATES WITH OXIDE INSERTS

    DOEpatents

    West, J.M.; Schumar, J.F.

    1958-06-10

    Planar-type fuel assemblies for nuclear reactors are described, particularly those comprising fuel in the oxide form such as thoria and urania. The fuel assembly consists of a plurality of parallel spaced fuel plate mennbers having their longitudinal side edges attached to two parallel supporting side plates, thereby providing coolant flow channels between the opposite faces of adjacent fuel plates. The fuel plates are comprised of a plurality of longitudinally extending tubular sections connected by web portions, the tubular sections being filled with a plurality of pellets of the fuel material and the pellets being thermally bonded to the inside of the tubular section by lead.

  2. Novel Photocatalytic Metal Oxides

    SciTech Connect

    Smith, Robert W.; Mei, Wai-Ning; Sabirianov, Renat; Wang, Lu

    2012-08-31

    The principal short-term objective is to develop improved solid-state photocatalysts for the decomposition of water into hydrogen gas using ultraviolet and visible solar radiation. We will pursue our objective by modeling candidate metal oxides through computer simulations followed by synthesis of promising candidates. We will characterize samples through standard experimental techniques. The long-term objective is to provide a more efficient source of hydrogen gas for fixed-site hydrogen fuel cells, particularly for energy users in remote locations.

  3. Heterogeneous Oxidation of Catechol.

    PubMed

    Pillar, Elizabeth A; Zhou, Ruixin; Guzman, Marcelo I

    2015-10-15

    Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air-solid interface under variable relative humidity (RH = 0-90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10(-6) occurs for 90% RH. Upon exposure of ca. 104-μm thick catechol films to O3(g) mixing ratios between 230 ppbv and 25 ppmv, three main reaction pathways are observed. (1) The cleavage of the 1,2 carbon-carbon bond at the air-solid interface resulting in the formation of cis,cis-muconic acid via primary ozonide and hydroperoxide intermediates. Further direct ozonolysis of cis,cis-muconic yields glyoxylic, oxalic, crotonic, and maleic acids. (2) A second pathway is evidenced by the presence of Baeyer-Villiger oxidation products including glutaconic 4-hydroxy-2-butenoic and 5-oxo-2-pentenoic acids during electrospray ionization mass spectrometry (MS) and ion chromatography MS analyses. (3) Finally, indirect oxidation by in situ produced hydroxyl radical (HO(•)) results in the generation of semiquinone radical intermediates toward the synthesis of polyhydoxylated aromatic rings such as tri-, tetra-, and penta-hydroxybenzene. Remarkably, heavier polyhydroxylated biphenyl and terphenyl products present in the extracted oxidized films result from coupling reactions of semiquinones of catechol and its polyhydroxylated rings. The direct ozonolysis of 1,2,3- and 1,2,4-trihydroxybenezene yields 2- and 3-hydroxy-cis,cis-muconic acid, respectively. The production of 2,4- or 3,4-dihdroxyhex-2-enedioic acid is

  4. Ultra supercritical steamside oxidation

    SciTech Connect

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

    2004-01-01

    Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions, which are part of the U.S. Department of Energy's Vision 21 goals. Most current coal power plants in the U.S. operate at a maximum steam temperature of 538 C. However, new supercritical plants worldwide are being brought into service with steam temperatures of up to 620 C. Vision 21 goals include steam temperatures of up to 760 C. This research examines the steamside oxidation of advanced alloys for use in USC systems. Emphasis is placed on alloys for high- and intermediate-pressure turbine sections. Initial results of this research are presented.

  5. Photocatalytic oxidation by uranyl

    SciTech Connect

    McCleskey, T.M.; Tumas, W.; Burns, C.J.

    1995-12-01

    The excited state of uranyl (UO{sub 2}{sup 2+}*) is a potent oxidant (E{sup 0}(UO{sub 2}{sup 2+}*/UO{sub 2}{sup +}) {approx} 2.5 V) which can be quenched by either electron transfer (ET) or H atom abstraction. We have investigated both types of quenching with a variety of organic substrates in water and acetone/water media. Excited-state reactions with alkenes proceed by ET to form cation radicals, while reactions with tertiary alkanes follow an H-atom abstraction pathway. In aqueous media uranyl photocatalytically decomposes tert-butyl peroxide in a manner analogous to Fenton-type chemistry.

  6. Oxidative Metabolism in Muscle

    NASA Astrophysics Data System (ADS)

    Ferrari, M.; Binzoni, T.; Quaresima, V.

    1997-06-01

    Oxidative metabolism is the dominant source of energy for skeletal muscle. Near-infrared spectroscopy allows the non-invasive measurement of local oxygenation, blood flow and oxygen consumption. Although several muscle studies have been made using various near-infrared optical techniques, it is still difficult to interpret the local muscle metabolism properly. The main findings of near-infrared spectroscopy muscle studies in human physiology and clinical medicine are summarized. The advantages and problems of near-infrared spectroscopy measurements, in resting and exercising skeletal muscles studies, are discussed through some representative examples.

  7. The 2016 oxide electronic materials and oxide interfaces roadmap

    NASA Astrophysics Data System (ADS)

    Lorenz, M.; Ramachandra Rao, M. S.; Venkatesan, T.; Fortunato, E.; Barquinha, P.; Branquinho, R.; Salgueiro, D.; Martins, R.; Carlos, E.; Liu, A.; Shan, F. K.; Grundmann, M.; Boschker, H.; Mukherjee, J.; Priyadarshini, M.; DasGupta, N.; Rogers, D. J.; Teherani, F. H.; Sandana, E. V.; Bove, P.; Rietwyk, K.; Zaban, A.; Veziridis, A.; Weidenkaff, A.; Muralidhar, M.; Murakami, M.; Abel, S.; Fompeyrine, J.; Zuniga-Perez, J.; Ramesh, R.; Spaldin, N. A.; Ostanin, S.; Borisov, V.; Mertig, I.; Lazenka, V.; Srinivasan, G.; Prellier, W.; Uchida, M.; Kawasaki, M.; Pentcheva, R.; Gegenwart, P.; Miletto Granozio, F.; Fontcuberta, J.; Pryds, N.

    2016-11-01

    Oxide electronic materials provide a plethora of possible applications and offer ample opportunity for scientists to probe into some of the exciting and intriguing phenomena exhibited by oxide systems and oxide interfaces. In addition to the already diverse spectrum of properties, the nanoscale form of oxides provides a new dimension of hitherto unknown phenomena due to the increased surface-to-volume ratio. Oxide electronic materials are becoming increasingly important in a wide range of applications including transparent electronics, optoelectronics, magnetoelectronics, photonics, spintronics, thermoelectrics, piezoelectrics, power harvesting, hydrogen storage and environmental waste management. Synthesis and fabrication of these materials, as well as processing into particular device structures to suit a specific application is still a challenge. Further, characterization of these materials to understand the tunability of their properties and the novel properties that evolve due to their nanostructured nature is another facet of the challenge. The research related to the oxide electronic field is at an impressionable stage, and this has motivated us to contribute with a roadmap on ‘oxide electronic materials and oxide interfaces’. This roadmap envisages the potential applications of oxide materials in cutting edge technologies and focuses on the necessary advances required to implement these materials, including both conventional and novel techniques for the synthesis, characterization, processing and fabrication of nanostructured oxides and oxide-based devices. The contents of this roadmap will highlight the functional and correlated properties of oxides in bulk, nano, thin film, multilayer and heterostructure forms, as well as the theoretical considerations behind both present and future applications in many technologically important areas as pointed out by Venkatesan. The contributions in this roadmap span several thematic groups which are represented by

  8. Au/metal oxides for low temperature CO oxidation

    SciTech Connect

    Srinivas, G.; Wright, J.; Bai, C.S.; Cook, R.

    1996-12-31

    Oxidation of carbon monoxide is important for several operations including fuel cells and carbon dioxide lasers. Room temperature CO oxidation has been investigated on a series of Au/metal oxide catalysts at conditions typical of spacecraft atmospheres; CO = 50 ppm, CO{sub 2} = 7,000 ppm, H{sub 2}O = 40% (RH) at 25{degrees}C, balance = air, and gas hourly space velocities of 7,000-60,000 hr{sup -1}. The addition of Au increases the room temperature CO oxidation activity of the metal oxides dramatically. All the Au/metal oxides deactivate during the CO oxidation reaction, especially in the presence of CO{sub 2} in the feed. The stability of the Au/metal oxide catalysts decreases in the following order: TiO{sub 2} > Fe{sub 2}O{sub 3} > NiO > Co{sub 3}O{sub 4}. The stability appears to decrease with an increase in the basicity of the metal oxides. In situ FTIR of CO adsorption on Au/TiO{sub 2} at 25{degrees}C indicates the formation of adsorbed CO, carboxylate, and carbonate species on the catalyst surface.

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

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

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

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

    DOEpatents

    Dunning, John S.; Alman, David E.

    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

  11. Oxidation of sulfites on vanadium-molybdenum oxides

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    PubMed

    Eng, Alex Yong Sheng; Ambrosi, Adriano; Chua, Chun Kiang; Saněk, Filip; Sofer, Zdeněk; 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.

  13. PREPARATION OF REFRACTORY OXIDE MICROSPHERE

    DOEpatents

    Haws, C.C. Jr.

    1963-09-24

    A method is described of preparing thorium oxide in the form of fused spherical particles about 1 to 2 microns in diameter. A combustible organic solution of thorium nitrate containing additive metal values is dispersed into a reflected, oxygen-fed flame at a temperature above the melting point of the resulting oxide. The metal additive is aluminum at a proportion such as to provide 1 to 10 weight per cent aluminum oxide in the product, silicon at the same proportion, or beryllium at a proportion of 12 to 25 weight per cent beryllium oxide in the product. A minor proportion of uranium values may also be provided in the solution. The metal additive lowers the oxide melting point and allows fusion and sphere formation in conventional equipment. The product particles are suitable for use in thorium oxide slurries for nuclear reactors. (AEC)

  14. Low Temperature Oxidation Catalyst

    NASA Technical Reports Server (NTRS)

    1995-01-01

    One day soon homeowners everywhere may be protected from deadly carbon monoxide fumes, thanks to a device invented at NASA Langley Research Center in Hampton, Va. It uses a new class of low-temperature oxidation catalysts to convert carbon monoxide to non-toxic carbon dioxide at room temperature. It can also remove formaldehyde from the air. The catalysts initially were developed for research involving carbon dioxide lasers. Industry already has shown an interest. Rochester Gas and Electric Co., of Rochester, N.Y., has an agreement with NASA Langley to develop a product for habitable spaces such as homes, cars and aircraft. The Mantic Corp., of Salt Lake City, Utah, plans to use them in breathing apparatus, such as firefighter masks. The catalysts also have applications as trace-gas detectors, and in cold-engine emission control. To work, the catalysts - tin oxide and platinum - are applied to a surface. Air passing over the surface reacts with the catalysts, transforming carbon monoxide and formaldehyde. The device requires no energy for operation, doesn't need to be plugged in, has no moving parts and lasts a long time.

  15. Nitric oxide and cancer

    PubMed Central

    Muntané, Jordi; la Mata, Manuel De

    2010-01-01

    Nitric oxide (NO) is a lipophilic, highly diffusible and short-lived physiological messenger which regulates a variety of important physiological responses including vasodilation, respiration, cell migration, immune response and apoptosis. NO is synthesized by three differentially gene-encoded NO synthase (NOS) in mammals: neuronal NOS (nNOS or NOS-1), inducible NOS (iNOS or NOS-2) and endothelial NOS (eNOS or NOS-3). All isoforms of NOS catalyze the reaction of L-arginine, NADPH and oxygen to NO, L-citrulline and NADP. NO may exert its cellular action by cGMP-dependent as well as by cGMP-independent pathways including postranslational modifications in cysteine (S-nitrosylation or S-nitrosation) and tyrosine (nitration) residues, mixed disulfide formation (S-nitrosoglutathione or GSNO) or promoting further oxidation protein stages which have been related to altered protein function and gene transcription, genotoxic lesions, alteration of cell-cycle check points, apoptosis and DNA repair. NO sensitizes tumor cells to chemotherapeutic compounds. The expression of NOS-2 and NOS-3 has been found to be increased in a variety of human cancers. The multiple actions of NO in the tumor environment is related to heterogeneous cell responses with particular attention in the regulation of the stress response mediated by the hypoxia inducible factor-1 and p53 generally leading to growth arrest, apoptosis or adaptation. PMID:21161018

  16. Biotransformation of nitric oxide

    SciTech Connect

    Yoshida, K.; Kasama, K.

    1987-08-01

    Previous investigations into the health effects of nitrogen oxides (NO/sub x/) have mostly been conducted with special reference to nitrogen dioxide (NO/sub 2/) and its direct effects on the respiratory system, while the study of nitric oxide (NO) has been disregarded. The authors carried out a study on NO by exposing rats and mice to /sup 15/NO or administering /sup 15/N-nitrite and /sup 15/N-nitrate to these animals by IP injection in order to elucidate the metabolic fate of NO. The results of their study and previous findings led them to assume that the major metabolic path of inhaled NO is as follows: inhaled NO reacts with hemoglobin, forming nitrosyl-hemoglobin (NOHb), and from NOHb, nitrate (NO/sub 2//sup -/ and nitrate (NO/sub 3//sup -/) are generated. Major quantities of NO/sub 3//sup -/ are discharged into the urine and a certain amount is discharged into the oral cavity through the salivary glands and transformed to NO/sub 2//sup -/. Part of this NO/sub 2//sup -/ is converted to N/sub 2/ gas in the stomach. Nitrate in the intestine is partly reduced to ammonia (NH/sub 3/) through NO/sub 2//sup -/, reabsorbed into the body, and converted to urea. Most of the metabolites of inhaled NO are excreted rapidly from the body within 48 hr.

  17. 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.

  18. Zinc oxide varistors and/or resistors

    DOEpatents

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

    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.

  19. 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.

  20. Buried oxide layer in silicon

    DOEpatents

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

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

  1. Continuous lengths of oxide superconductors

    DOEpatents

    Kroeger, Donald M.; List, III, Frederick A.

    2000-01-01

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

  2. Novel method for controlled oxidation

    SciTech Connect

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

    1981-01-01

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

  3. HYDROCARBON OXIDATION OVER VANADIUM PHOSPHORUS OXIDE CATALYST USING HYDROGEN PEROXIDE

    EPA Science Inventory

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

  4. Sulfite oxidizing enzymes

    PubMed Central

    Feng, Changjian; Tollin, Gordon; Enemark, John H.

    2007-01-01

    Sulfite oxidizing enzymes are essential mononuclear molybdenum (Mo) proteins involved in sulfur metabolism of animals, plants and bacteria. There are three such enzymes presently known: (1) sulfite oxidase (SO) in animals, (2) SO in plants, and (3) sulfite dehydrogenase (SDH) in bacteria. X-ray crystal structures of enzymes from all three sources (chicken SO, Arabidopsis thaliana SO, and Starkeya novella SDH) show nearly identical square pyramidal coordination around the Mo atom, even though the overall structures of the proteins and the presence of additional cofactors vary. This structural information provides a molecular basis for studying the role of specific amino acids in catalysis. Animal SO catalyzes the final step in the degradation of sulfur-containing amino acids and is critical in detoxifying excess sulfite. Human SO deficiency is a fatal genetic disorder that leads to early death, and impaired SO activity is implicated in sulfite neurotoxicity. Animal SO and bacterial SDH contain both Mo and heme domains, whereas plant SO only has the Mo domain. Intraprotein electron transfer (IET) between the Mo and Fe centers in animal SO and bacterial SDH is a key step in the catalysis, which can be studied by laser flash photolysis in the presence of deazariboflavin. IET studies on animal SO and bacterial SDH clearly demonstrate the similarities and differences between these two types of sulfite oxidizing enzymes. Conformational change is involved in the IET of animal SO, in which electrostatic interactions may play a major role in guiding the docking of the heme domain to the Mo domain prior to electron transfer. In contrast, IET measurements for SDH demonstrate that IET occurs directly through the protein medium, which is distinctly different from that in animal SO. Point mutations in human SO can result in significantly impaired IET or no IET, thus rationalizing their fatal effects. The recent developments in our understanding of sulfite oxidizing enzyme

  5. Ferromagnet / superconductor oxide superlattices

    NASA Astrophysics Data System (ADS)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  6. Liquid-phase oxidation of cyclohexanone over cerium oxide catalyst

    SciTech Connect

    Shen, H.C. ); Weng, H.S. )

    1990-05-01

    Catalytic oxidation of cyclohexanone in the liquid phase with glacial acetic acid as the solvent over cerium oxide was studied between 5 and 15 atm and 98 and 118 {degrees} C in a batch reactor. The products were adipic acid, glutaric acid, succinic acid, caprolactone, carbon oxides, etc. The reaction undergoes a short induction period prior to a rapid reaction regime. In both regimes, the reaction is independent of oxygen pressure when the system pressure is above 10 atm. The induction period is inversely proportional to both of the catalyst weight and cyclohexanone concentration.During the rapid reaction regime, the reaction rate was found to be proportional to the 0.5 power of the catalyst weight and to the 1.5 power of the cyclohexanone concentration. Reaction mechanisms and rate expressions are proposed. The carbon oxides produced in this study were much lower than those previously reported. The cerium oxide catalyst is stable during the reaction.

  7. 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.

  8. The oxidation behavior of Co-15 wt % Cr alloy containing dispersed oxides formed by internal oxidation

    SciTech Connect

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

    1991-12-01

    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 of various pretreatments on the subsequent oxidation of these alloys was studied at 1000{degree}C, and compared with that of Co-15wt%Cr-1wt%Si alloy. The main purpose of this study was to determine the relative effectiveness of the dispersed oxide particles and the contaminated silicon on the selective oxidation of chromium. It was found that the oxidation behavior of both treated alloys were strongly affected by the degree of silicon contamination. Selective oxidation of chromium to form a nearly continuous protective Cr{sub 2}O{sub 3} scale was achieved with greater than 0.4wt% silicon. The presence of dispersed particles reduced initial oxidation rate, but was ineffective in promoting Cr{sub 2}O{sub 3} scale formation.

  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. Effects of Oxidation on Oxidation-Resistant Graphite

    SciTech Connect

    Windes, William; Smith, Rebecca; Carroll, Mark

    2015-05-01

    The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

  11. Biological water oxidation.

    PubMed

    Cox, Nicholas; Pantazis, Dimitrios A; Neese, Frank; Lubitz, Wolfgang

    2013-07-16

    Photosystem II (PSII), a multisubunit pigment-protein supercomplex found in cyanobacteria, algae, and plants, catalyzes a unique reaction in nature: the light-driven oxidation of water. Remarkable recent advances in the structural analysis of PSII now give a detailed picture of the static supercomplex on the molecular level. These data provide a solid foundation for future functional studies, in particular the mechanism of water oxidation and oxygen release. The catalytic core of the PSII is a tetramanganese-calcium cluster (Mn₄O₅Ca), commonly referred to as the oxygen-evolving complex (OEC). The function of the OEC rests on its ability to cycle through five metastable states (Si, i = 0-4), transiently storing four oxidizing equivalents, and in so doing, facilitates the four electron water splitting reaction. While the latest crystallographic model of PSII gives an atomic picture of the OEC, the exact connectivity within the inorganic core and the S-state(s) that the X-ray model represents remain uncertain. In this Account, we describe our joint experimental and theoretical efforts to eliminate these ambiguities by combining the X-ray data with spectroscopic constraints and introducing computational modeling. We are developing quantum chemical methods to predict electron paramagnetic resonance (EPR) parameters for transition metal clusters, especially focusing on spin-projection approaches combined with density functional theory (DFT) calculations. We aim to resolve the geometric and electronic structures of all S-states, correlating their structural features with spectroscopic observations to elucidate reactivity. The sequence of manganese oxidations and concomitant charge compensation events via proton transfer allow us to rationalize the multielectron S-state cycle. EPR spectroscopy combined with theoretical calculations provides a unique window into the tetramangenese complex, in particular its protonation states and metal ligand sphere evolution, far

  12. Polymorphism of phosphoric oxide

    USGS Publications Warehouse

    Hill, W.L.; Faust, G.T.; Hendricks, S.B.

    1943-01-01

    The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

  13. Phosphine oxide surfactants revisited.

    PubMed

    Stubenrauch, Cosima; Preisig, Natalie; Laughlin, Robert G

    2016-04-01

    This review summarizes everything we currently know about the nonionic surfactants alkyl dimethyl (C(n)DMPO) and alkyl diethyl (C(n)DEPO) phosphine oxide (PO surfactants). The review starts with the synthesis and the general properties (Section 2) of these compounds and continues with their interfacial properties (Section 3) such as surface tension, surface rheology, interfacial tension and adsorption at solid surfaces. We discuss studies on thin liquid films and foams stabilized by PO surfactants (Section 4) as well as studies on their self-assembly into lyotropic liquid crystals and microemulsions, respectively (Section 5). We aim at encouraging colleagues from both academia and industry to take on board PO surfactants whenever possible and feasible because of their broad variety of excellent properties. PMID:26869216

  14. Main Oxidizer Valve Design

    NASA Technical Reports Server (NTRS)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  15. Oxycodone N-oxide.

    PubMed

    Sonar, Vijayakumar N; Parkin, Sean; Crooks, Peter A

    2012-11-01

    The title compound, (5R,9R,13S,14S,17R)-14-hydroxy-3-methoxy-17-methyl-4,5-epoxymorphinan-6-one N-oxide, C(18)H(21)NO(5), has been prepared in a diastereomerically pure form by the reaction of oxycodone with 3-chloroperbenzoic acid and subsequent crystallization of the product from chloroform. The crystal packing shows that the molecule exhibits intramolecular O-H···O [D···A = 2.482 (2) Å] hydrogen bonding. In addition, there are weak intermolecular C-H...O interactions which, along with van der Waals forces, stabilize the structure. The new chiral center at the 17-position is demonstrated to be R.

  16. Wet oxidation of a spacecraft model waste

    NASA Technical Reports Server (NTRS)

    Johnson, C. C.; Wydeven, T.

    1985-01-01

    Wet oxidation was used to oxidize a spacecraft model waste under different oxidation conditions. The variables studied were pressure, temperature, duration of oxidation, and the use of one homogeneous and three heterogeneous catalysts. Emphasis is placed on the final oxidation state of carbon and nitrogen since these are the two major components of the spacecraft model waste and two important plant nutrients.

  17. 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.

  18. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, Joseph L.; Hung, Cheng-Hung

    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.

  19. 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.

  20. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  1. 21 CFR 184.1545 - Nitrous oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrous oxide. 184.1545 Section 184.1545 Food and... Substances Affirmed as GRAS § 184.1545 Nitrous oxide. (a) Nitrous oxide (empirical formula N2O, CAS Reg. No.... Nitrous oxide is manufactured by the thermal decomposition of ammonium nitrate. Higher oxides of...

  2. Complex oxides: Intricate disorder

    DOE PAGES

    Uberuaga, Blas Pedro

    2016-02-29

    In this study, complex oxides such as pyrochlores have a myriad of potential technological applications, including as fast ion conductors and radiation-tolerant nuclear waste forms. They are also of interest for their catalytic and spin ice properties. Many of these functional properties are enabled by the atomic structure of the cation sublattices. Pyrochlores (A2B2O7) contain two different cations (A and B), typically a 3+ rare earth and a 4+ transition metal such as Hf, Zr, or Ti. The large variety of chemistries that can form pyrochlores leads to a rich space in which to search for exotic new materials. Furthermore,more » how cations order or disorder on their respective sublattices for a given chemical composition influences the functional properties of the oxide. For example, oxygen ionic conductivity is directly correlated with the level of cation disorder — the swapping of A and B cations1. Further, the resistance of these materials against amorphization has also been connected with the ability of the cations to disorder2, 3. These correlations between cation structure and functionality have spurred great interest in the structure of the cation sublattice under irradiation, with significant focus on the disordering mechanisms and disordered structure. Previous studies have found that, upon irradiation, pyrochlores often undergo an order-to-disorder transformation, in which the resulting structure is, from a diffraction point of view, indistinguishable from fluorite (AO2) (ref. 3). Shamblin et al. now reveal that the structure of disordered pyrochlore is more complicated than previously thought4.« less

  3. The oxidation of carbonized binders

    SciTech Connect

    Prokushin, V.N.; Fedoseev, S.D.; Kleimenov, V.V.; Kovaneva, M.A.; Marochkin, E.P.; Smyslov, V.I.; Trapeznikov, N.M.

    1983-01-01

    The oxidation by air of carbonized binders used in the production of carbonaceous materials has been studied by the derivatographic method. The effective activation energies of the process have been calculated. Of the materials investigated, the greatest oxidative resistance was possessed by coke obtained from medium-temperature hard-coal pitch.

  4. 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.

  5. Metal oxide films on metal

    DOEpatents

    Wu, Xin D.; Tiwari, Prabhat

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  6. Detection of nitric oxide pollution

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  7. Catalysts for low temperature oxidation

    DOEpatents

    Toops, Todd J.; Parks, III, James E.; Bauer, John C.

    2016-03-01

    The invention provides a composite catalyst containing a first component and a second component. The first component contains nanosized gold particles. The second component contains nanosized platinum group metals. The composite catalyst is useful for catalyzing the oxidation of carbon monoxide, hydrocarbons, oxides of nitrogen, and other pollutants at low temperatures.

  8. Oxidation and photooxidation of asphalts

    SciTech Connect

    Mill, T.; Tse, D. )

    1990-07-01

    Oxidation of asphalt is a major cause of pavement failure owing to hardening of the asphalt binder with accompanying changes in viscosity, separation of components, embrittlement and loss of cohesion and adhesion of the asphalt in the mix. However oxidation of asphalt-aggregate mixes at high temperature is deliberately done to partly harden the mix prior to laydown; hardening then continues during cooling. Excessive hardening at this point is undesirable because of embrittlement and cracking. Slow oxidation of asphalt continues during the service life of the roadbed at a rate that appears to be partly determined by the void volume of the roadbed, as well as the properties of the asphalt and (possibly) the properties of the aggregate. The authors focused their efforts on understanding the mechanistic basis for slow oxidation of asphalt under service conditions in order to predict how rapidly an asphalt will oxidize, based on its composition, and to find better ways to inhibit the process under service conditions.

  9. Thermal oxidation of gallium arsenide

    SciTech Connect

    Monteiro, O.R.; Evans, J.W.

    1989-01-01

    Here we present some results of transmission electron microscopy and secondary ion mass spectroscopy of thermally oxidized gallium arsenide with different types of dopants. At temperatures below 400 /sup 0/C an amorphous oxide is formed. Oxidation at temperatures between 500 and 600 /sup 0/C initially produces an epitaxial film of ..gamma..-Ga/sub 2/O/sub 3/. As the reaction proceeds, this film becomes polycrystalline and then transforms to ..beta..-Ga/sub 2/O/sub 3/. This film contains small crystallites of As/sub 2/O/sub 5/ and As/sub 2/O/sub 3/ in the case of the chromium doped samples, whereas only the former was detected in the case of silicon and tellurium doped samples. Elemental arsenic was always found at the interface between the oxide and GaAs. Chromium doped gallium also exhibited a slower oxidation kinetics than the other materials.

  10. Stabilization of elusive silicon oxides.

    PubMed

    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-(i)Pr2C6H3)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.

  11. Engelhard expands oxidation catalysts portfolio

    SciTech Connect

    Rotman, D.

    1997-02-26

    Engelhard says its agreement earlier this month to market Amoco Chemical`s proprietary maleic anhydride catalyst reflects an effort to expand its speciality catalysts business (CW, Feb. 19, p.5). In particular, the company says it is looking for additional alliances to bolster its oxidation catalysts portfolio. {open_quotes}There are some areas of oxidation catalysis that are reasonably attractive,{close_quotes} says Paul Lamb, marketing director/chemical catalysts. He says that while Engelhard is not interested in commodity oxidation catalysts, such as those used to make sulfuric acid, it does want to boost offerings for higher-value oxidation catalysts. Engelhard is collaborating with Geon to offer oxychlorination catalysts for making ethylene dichloride. It also markets oxidation catalysts for vinyl acetate production.

  12. Photocatalytic oxidation of methane over silver decorated zinc oxide nanocatalysts.

    PubMed

    Chen, Xuxing; Li, Yunpeng; Pan, Xiaoyang; Cortie, David; Huang, Xintang; Yi, Zhiguo

    2016-01-01

    The search for active catalysts that efficiently oxidize methane under ambient conditions remains a challenging task for both C1 utilization and atmospheric cleansing. Here, we show that when the particle size of zinc oxide is reduced down to the nanoscale, it exhibits high activity for methane oxidation under simulated sunlight illumination, and nano silver decoration further enhances the photo-activity via the surface plasmon resonance. The high quantum yield of 8% at wavelengths <400 nm and over 0.1% at wavelengths ∼470 nm achieved on the silver decorated zinc oxide nanostructures shows great promise for atmospheric methane oxidation. Moreover, the nano-particulate composites can efficiently photo-oxidize other small molecular hydrocarbons such as ethane, propane and ethylene, and in particular, can dehydrogenize methane to generate ethane, ethylene and so on. On the basis of the experimental results, a two-step photocatalytic reaction process is suggested to account for the methane photo-oxidation. PMID:27435112

  13. Photocatalytic oxidation of methane over silver decorated zinc oxide nanocatalysts

    PubMed Central

    Chen, Xuxing; Li, Yunpeng; Pan, Xiaoyang; Cortie, David; Huang, Xintang; Yi, Zhiguo

    2016-01-01

    The search for active catalysts that efficiently oxidize methane under ambient conditions remains a challenging task for both C1 utilization and atmospheric cleansing. Here, we show that when the particle size of zinc oxide is reduced down to the nanoscale, it exhibits high activity for methane oxidation under simulated sunlight illumination, and nano silver decoration further enhances the photo-activity via the surface plasmon resonance. The high quantum yield of 8% at wavelengths <400 nm and over 0.1% at wavelengths ∼470 nm achieved on the silver decorated zinc oxide nanostructures shows great promise for atmospheric methane oxidation. Moreover, the nano-particulate composites can efficiently photo-oxidize other small molecular hydrocarbons such as ethane, propane and ethylene, and in particular, can dehydrogenize methane to generate ethane, ethylene and so on. On the basis of the experimental results, a two-step photocatalytic reaction process is suggested to account for the methane photo-oxidation. PMID:27435112

  14. Oxidative decarboxylation of diclofenac by manganese oxide bed filter.

    PubMed

    Huguet, Mélissa; Deborde, Marie; Papot, Sébastien; Gallard, Hervé

    2013-09-15

    Diclofenac (DCF) was eliminated by fast chemical oxidation on natural manganese oxide in a column reactor. Identification of transformation by-products of DCF by HPLC-UV-MS(n) gave evidence of decarboxylation, iminoquinone formation and dimerization. The fast oxidation of DCF is also accompanied by a strong adsorption of organic carbon that was explained by the sorption of dimer products on the surface of manganese oxide. Decarboxylation and dimerization increased the hydrophobic interactions with manganese oxide and reduced the presence of potentially toxic by-products in the effluent. The rate of oxidation was first order with respect to DCF and was slowed down by the presence of organic buffer MOPS (3-morpholinopropane-1-sulfonic acid). The first order rate constant in absence of MOPS was extrapolated by considering a surface site-binding model and MOPS as a co-adsorbate. The rate constant was 0.818 min(-1) at pH 7 and 10 mM NaCl corresponding to empty bed residence time of 50 s only for 50% removal of DCF. Rate constants increased when pH decreased from pH 8.0 to 6.5 and when ionic strength increased. Manganese oxide bed filter can be considered as an alternative treatment for polishing waste water effluent or for remediation of contaminated groundwater.

  15. New developments in oxidative fermentation.

    PubMed

    Adachi, O; Moonmangmee, D; Toyama, H; Yamada, M; Shinagawa, E; Matsushita, K

    2003-02-01

    Oxidative fermentations have been well established for a long time, especially in vinegar and in L-sorbose production. Recently, information on the enzyme systems involved in these oxidative fermentations has accumulated and new developments are possible based on these findings. We have recently isolated several thermotolerant acetic acid bacteria, which also seem to be useful for new developments in oxidative fermentation. Two different types of membrane-bound enzymes, quinoproteins and flavoproteins, are involved in oxidative fermentation, and sometimes work with the same substrate but produce different oxidation products. Recently, there have been new developments in two different oxidative fermentations, D-gluconate and D-sorbitol oxidations. Flavoproteins, D-gluconate dehydrogenase, and D-sorbitol dehydrogenase were isolated almost 2 decades ago, while the enzyme involved in the same oxidation reaction for D-gluconate and D-sorbitol has been recently isolated and shown to be a quinoprotein. Thus, these flavoproteins and a quinoprotein have been re-assessed for the oxidation reaction. Flavoprotein D-gluconate dehydrogenase and D-sorbitol dehydrogenase were shown to produce 2-keto- D-gluconate and D-fructose, respectively, whereas the quinoprotein was shown to produce 5-keto- D-gluconate and L-sorbose from D-gluconate and D-sorbitol, respectively. In addition to the quinoproteins described above, a new quinoprotein for quinate oxidation has been recently isolated from Gluconobacter strains. The quinate dehydrogenase is also a membrane-bound quinoprotein that produces 3-dehydroquinate. This enzyme can be useful for the production of shikimate, which is a convenient salvage synthesis system for many antibiotics, herbicides, and aromatic amino acids synthesis. In order to reduce energy costs of oxidative fermentation in industry, several thermotolerant acetic acid bacteria that can grow up to 40 degrees C have been isolated. Of such isolated strains, some

  16. 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.

  17. Treatment of Fatty Acid Oxidation Disorders

    MedlinePlus

    ... of fatty acid oxidation disorders Treatment of fatty acid oxidation disorders E-mail to a friend Please ... page It's been added to your dashboard . Fatty acid oxidation disorders are rare health conditions that affect ...

  18. 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

  19. The oxidation of carbon monoxide using tin oxide based catalysts

    NASA Technical Reports Server (NTRS)

    Sampson, Christopher F.; Jorgensen, Norman

    1990-01-01

    The preparation conditions for precious metal/tin oxide catalysts were optimized for maximum carbon monoxide/oxygen recombination efficiency. This was achieved by controlling the tin digestion, the peptization to form the sol, the calcination process and the method of adding the precious metals. Extensive studies of the tin oxide structure were carried out over the temperature range 20 to 500 C in air or hydrogen environments using Raman scattering and X ray diffraction. Adsorbed species on tin oxide, generated in an environment containing carbon monoxide, gave rise to a Raman band at about 1600 cm(exp -1) which was assigned to carbonaceous groups, possible carbonate.

  20. 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

  1. Zinc oxide nanorods

    NASA Astrophysics Data System (ADS)

    Chik, Hope Wuming

    Non-lithographic, bottom-up techniques have been developed to advance the state of the art and contribute to the development of new material structures, fabrication methods, devices, and applications using the Zinc Oxide material system as a demonstration vehicle. The novel low temperature catalytic vapour-liquid-solid growth process developed is technologically simple, inexpensive, and a robust fabrication technique offering complete control over the physical dimensions of the nanorod such as its diameter and length, and over the positioning of the nanorods for site-selective growth. By controlling the distribution of the Au catalysts with the use of a self-organized anodized aluminum oxide nanopore membrane as a template, we have been able to synthesize highly ordered, hexagonally packed, array of ZnO nanorods spanning a large area. These nanorods are single crystal, hexagonally shaped, indicative of the wurtzite structure, and are vertically aligned to the substrate. By pre-patterning the template, arbitrary nanorod patterns can be formed. We have also demonstrated the assembly of the nanorods into functional devices using controlled methods that are less resource intensive, easily scalable, and adaptable to other material systems, without resorting to the manipulation of each individual nanostructures. Examples of these devices include the random network device that exploits the common attributes of the nanorods, and those formed using an external field to control the nanorod orientation. Two and three terminal device measurements show that the as-grown nanorods are n-type doped, and that by controlling the external optical excitation and its test environment, the photoconductivity can be altered dramatically. Self assemble techniques such as the spontaneous formation of nanodendrites into complex networks of interconnects were studied. Controlled formation of interconnects achieved by controlling the placement of the catalyst is demonstrated by growing the

  2. Oxidants, antioxidants and carcinogenesis.

    PubMed

    Ray, Gibanananda; Husain, Syed Akhtar

    2002-11-01

    Reactive oxygen metabolites (ROMs), such as superoxide anions (O2*-) hydrogen peroxide (H2O2), and hydroxyl radical (*OH), malondialdehyde (MDA) and nitric oxide (NO) are directly or indirectly involved in multistage process of carcinogenesis. They are mainly involved in DNA damage leading sometimes to mutations in tumour suppressor genes. They also act as initiator and/or promotor in carcinogenesis. Some of them are mutagenic in mammalian systems. O2*-, H2O2 and *OH are reported to be involved in higher frequencies of sister chromatid exchanges (SCEs) and chromosome breaks and gaps (CBGs). MDA, a bi-product of lipid peroxidation (LPO), is said to be involved in DNA adduct formations, which are believed to be responsible for carcinogenesis. NO, on the other hand, plays a duel role in cancer. At high concentration it kills tumour cells, but at low concentration it promotes tumour growth and metastasis. It causes DNA single and double strand breaks. The metabolites of NO such as peroxynitrite (OONO-) is a potent mutagen that can induce transversion mutations. NO can stimulate O2*-/H2O2/*OH-induced LPO. These deleterious actions of oxidants can be countered by antioxidant defence system in humans. There are first line defense antioxidants such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT). SOD converts O2*- to H2O2, which is further converted to H2O with the help of GPx and CAT. SOD inhibits *OH production. SOD also act as antipoliferative agent, anticarcinogens, and inhibitor at initiation and promotion/transformation stage in carcinogenesis. GPx is another antioxidative enzyme which catalyses to convert H2O2, to H2O. The most potent enzyme is CAT. GPx and CAT are important in the inactivation of many environmental mutagens. CAT is also found to reduce the SCE levels and chromosomal aberrations. Antioxidative vitamins such as vitamin A, E, and C have a number of biological activities such as immune stimulation, inhibition of

  3. The oxidation and corrosion of ODS alloys

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  4. Surface-Step-Induced Oscillatory Oxide Growth

    NASA Astrophysics Data System (ADS)

    Li, Liang; Luo, Langli; Ciston, Jim; Saidi, Wissam A.; Stach, Eric A.; Yang, Judith C.; Zhou, Guangwen

    2014-09-01

    We report in situ atomic-resolution transmission electron microscopy observations of the oxidation of stepped Cu surfaces. We find that the presence of surface steps both inhibits oxide film growth and leads to the oxide decomposition, thereby resulting in oscillatory oxide film growth. Using atomistic simulations, we show that the oscillatory oxide film growth is induced by oxygen adsorption on the lower terrace along the step edge, which destabilizes the oxide film formed on the upper terrace.

  5. Manganese oxidation by Leptothrix discophora.

    PubMed

    Boogerd, F C; de Vrind, J P

    1987-02-01

    Cells of Leptothrix discophora SS1 released Mn2+-oxidizing factors into the medium during growth in batch culture. Manganese was optimally oxidized when the medium was buffered with HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid) at pH 7.5. Manganese-oxidizing activity in the culture medium in which this strain had been grown previously was sensitive to heat, phosphate, Tris, NaN3, HgCl2 NaCl, sodium dodecyl sulfate, and pronase; 0.5 mol of O2 was consumed per mol of MnO2 formed. During Mn2+ oxidation, protons were liberated. With sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two protein-containing bands were detected in the spent culture medium. One band had an apparent molecular weight of 110,000 and was predominant in Mn2+-oxidizing activity. The second product (Mr 85,000) was only detected in some cases and probably represents a proteolytic breakdown moiety of the 110,000-Mr protein. The Mn2+-oxidizing factors were associated with the MnO2 aggregates that had been formed in spent culture medium. After solubilization of this MnO2 with ascorbate, Mn2+-oxidizing activity could be recovered. PMID:3804969

  6. Compound semiconductor oxide antireflection coatings

    NASA Astrophysics Data System (ADS)

    Knopp, K. J.; Mirin, R. P.; Bertness, K. A.; Silverman, K. L.; Christensen, D. H.

    2000-05-01

    We report the development of high quality, broad-bandwidth, antireflection (AR) coatings using the low index provided by wet thermally oxidized Al0.98Ga0.02As. We address the design criteria, fabrication, and characterizations of AR coatings composed of surface and buried oxide layers on GaAs. We show, using native-oxide dispersion data, that surface oxide coatings can be designed to offer a nearly zero minimum of reflectance and a reflectance of <1% over bandwidths as large as 500 nm. Surface coatings having a reflectance minimum of 0.4% and a reflectance of <1% over >250 nm have been experimentally demonstrated at a design wavelength of 1 micrometer. Additionally, buried oxide coatings can be designed with an AlxGa1-xAs matching layer of any composition to exactly match the admittance of any substrate with effective index between 2.5 and 3.5. We have demonstrated buried oxide coatings, also designed for 1 micrometer, having a reflectance minimum of 0.4% and a reflectance of <1% over 21 nm. The calculated optical scattering loss from measured roughness data indicates that reflectance minima as low as 10-4 % are ultimately achievable with native-oxide antireflection coatings.

  7. (Oxidation of intermetallics and ceramics)

    SciTech Connect

    DeVan, J.H.; Tortorelli, P.F.

    1990-05-11

    The travelers presented papers at the Conference on Microscopy of Oxidation and learned about new applications of microscopic techniques to studies of oxides scales. Mr. DeVan visited the Corrosion and Protection Centre at UMIST to discuss oxidation of Fe{sub 3}Al. Dr. Tortorelli visited Cranfield Institute of Technology to discuss the mechanical properties of oxide scales. Both travelers visited the Coal Research Establishment of British Coal to review results from exposure of Fe{sub 3}Al in a gasifier environment and plans for development of advanced coal-fired power generation utilizing a topping cycle. The ORNL staff members independently visited Harwell Laboratory to present results on oxidation of Ni{sub 3}Al composites, discuss indentation testing of oxide scales, and help conduct a secondary ion mass spectrometry (SIMS) investigation of oxidized Ni{sub 3}Al--Al{sub 2}O{sub 3}. Harwell was underground a change from a national laboratory to a profit-based business venture.

  8. The surface oxidation of pyrite

    NASA Astrophysics Data System (ADS)

    Buckley, A. N.; Woods, R.

    1987-02-01

    The surface oxidation in air and air-saturated aqueous solutions of the iron sulfide mineral, pyrite, has been studied by X-ray photoelectron spectroscopy. Iron sulfate was produced on fracture surfaces within the first few minutes of exposure to air under ambient conditions. Iron oxide was also included in the oxidation products after prolonged exposure which implies that a sulfur product in addition to sulfate must be formed. It is suggested that this product is an iron-deficient sulfide. Elemental sulfur was not evident at surfaces exposed to air. Iron oxide rather than sulfate was present at abraded surfaces exposed to air for a few minutes. Oxidation of pyrite in air-saturated acid solutions resulted in the formation of a surface sulfur layer the extent and nature of which depended on solution composition and exposure time. Sulfate was the only sulfur oxidation product identified in alkaline solutions not containing soluble sulfide, and iron oxide remained at the surface after such treatment. Thin layers of elemental sulfur were observed at fracture surfaces immersed in aerated, dilute sodium sulfide solutions.

  9. Urinary Biomarkers of Oxidative Status

    PubMed Central

    Il’yasova, Dora; Scarbrough, Peter; Spasojevic, Ivan

    2012-01-01

    Oxidative damage produced by reactive oxygen species (ROS) has been implicated in the etiology and pathology of many health conditions, including a large number of chronic diseases. Urinary biomarkers of oxidative status present a great opportunity to study redox balance in human populations. With urinary biomarkers, specimen collection is non-invasive and the organic/metal content is low, which minimizes the artifactual formation of oxidative damage to molecules in specimens. Also, urinary levels of the biomarkers present intergraded indices of redox balance over a longer period of time compared to blood levels. This review summarizes the criteria for evaluation of biomarkers applicable to epidemiological studies and evaluation of several classes of biomarkers that are formed non-enzymatically: oxidative damage to lipids, proteins, DNA, and allantoin, an oxidative product of uric acid. The review considers formation, metabolism, and exertion of each biomarker, available data on validation in animal and clinical models of oxidative stress, analytical approaches, and their intra- and inter-individual variation. The recommended biomarkers for monitoring oxidative status over time are F2-isoprostanes and 8-oxodG. For inter-individual comparisons, F2-isoprostanes are recommended, whereas urinary 8-oxodG levels may be confounded by differences in the DNA repair capacity. Promising urinary biomarkers include allantoin, acrolein-lysine, and dityrosine. PMID:22683781

  10. Oxidation kinetics of aluminum diboride

    NASA Astrophysics Data System (ADS)

    Whittaker, Michael L.; Sohn, H. Y.; Cutler, Raymond A.

    2013-11-01

    The oxidation characteristics of aluminum diboride (AlB2) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB2 in the onset of oxidation and final conversion fraction, with AlB2 beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB2 and Al+2B in both air and oxygen. AlB2 exhibited O2-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O2 than in air. Differences in the composition and morphology between oxidized Al+2B and AlB2 suggested that Al2O3-B2O3 interactions slowed Al+2B oxidation by converting Al2O3 on aluminum particles into a Al4B2O9 shell, while the same Al4B2O9 developed a needle-like morphology in AlB2 that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB2, but both appear to be resistant to oxidation in cool, dry environments.

  11. Mixed oxide fuel development

    SciTech Connect

    Leggett, R.D.; Omberg, R.P.

    1987-05-08

    This paper describes the success of the ongoing mixed-oxide fuel development program in the United States aimed at qualifying an economical fuel system for liquid metal cooled reactors. This development has been the cornerstone of the US program for the past 20 years and has proceeded in a deliberate and highly disciplined fashion with high emphasis on fuel reliability and operational safety as major features of an economical fuel system. The program progresses from feature testing in EBR-II to qualifying full size components in FFTF under fully prototypic conditions to establish a basis for extending allowable lifetimes. The development program started with the one year (300 EFPD) core, which is the FFTF driver fuel, continued with the demonstration of a two year (600 EFPD) core and is presently evaluating a three year (900 EFPD) fuel system. All three of these systems, consistent with other LMR fuel programs around the world, use fuel pellets gas bonded to a cladding tube that is assembled into a bundle and fitted into a wrapper tube or duct for ease of insertion into a core. The materials of construction progressed from austenitic CW 316 SS to lower swelling austenitic D9 to non swelling ferritic/martensitic HT9. 6 figs., 2 tabs.

  12. Catalysts for hydrocarbon oxidation

    SciTech Connect

    Ott, K.C.; Paffett, M.T.; Earl, W.L.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The focus of this project was elucidating structural aspects of a titanosilicate TS-1 that is an oxidation catalyst. The authors have prepared samples of TS-1 and used scanning electron microscopy, high resolution transmission electron microscopy, and ultraviolet-visible spectroscopy to examine the samples of TS-1 for amorphous titanium-containing phases that may confound the analysis of the neutron scattering data. They observed that the volume fraction of titanium-containing impurity phases(s) determined from electron microscopy did not correlate well with that amount determined by ultraviolet-visible diffuse-reflectance spectroscopy. The authors also designed, constructed and tested a flow reactor that can be placed into the neutron flight path at the High Intensity Powder Diffractometer line at the Manual Lujan, Jr. Neutron Scattering Center. This reactor will allow for the observation of crystallographic changes of catalysts and other materials under reaction conditions.

  13. Oxidants from Pulverized Minerals

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2007-06-01

    Joel Hurowitz (previously at State University of New York at Stony Brook and now at the Jet Propulsion Laboratory), Nick Tosca, Scott McLennan, and Martin Schoonen (SUNY at Stony Brook) studied the production of hydrogen peroxide from freshly pulverized minerals in solution. Their experiments focused on olivine, augite, and labradorite; silicate minerals of basaltic planetary surfaces, such as the Moon and Mars, that are exposed to the intense crushing and grinding of impact cratering processes. The hydrogen peroxide produced in the experiments was enough to adequately explain the oxidizing nature of Martian regolith first determined by the Viking Landers and the results suggest, for the first time, that mechanically activated mineral surfaces may be an important part of the overall explanation for the Viking Lander biology experiment results. Hurowitz and coauthors further showed that when the pulverized minerals are heat-treated to high temperature under vacuum (to cause dehydroxylation) there is almost a 20 times increase in hydrogen peroxide production, a result which may be highly relevant to lunar dust. These careful studies demonstrate the importance of and concern about reactive dusts on planetary surfaces from two standpoints: the health of astronauts on surface maneuvers who may inadvertently breath it and the viability of possible Martian organic species to survive in such a corrosive, antiseptic surface environment.

  14. Oxidative desulfurization: kinetic modelling.

    PubMed

    Dhir, S; Uppaluri, R; Purkait, M K

    2009-01-30

    Increasing environmental legislations coupled with enhanced production of petroleum products demand, the deployment of novel technologies to remove organic sulfur efficiently. This work represents the kinetic modeling of ODS using H(2)O(2) over tungsten-containing layered double hydroxide (LDH) using the experimental data provided by Hulea et al. [V. Hulea, A.L. Maciuca, F. Fajula, E. Dumitriu, Catalytic oxidation of thiophenes and thioethers with hydrogen peroxide in the presence of W-containing layered double hydroxides, Appl. Catal. A: Gen. 313 (2) (2006) 200-207]. The kinetic modeling approach in this work initially targets the scope of the generation of a superstructure of micro-kinetic reaction schemes and models assuming Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. Subsequently, the screening and selection of above models is initially based on profile-based elimination of incompetent schemes followed by non-linear regression search performed using the Levenberg-Marquardt algorithm (LMA) for the chosen models. The above analysis inferred that Eley-Rideal mechanism describes the kinetic behavior of ODS process using tungsten-containing LDH, with adsorption of reactant and intermediate product only taking place on the catalyst surface. Finally, an economic index is presented that scopes the economic aspects of the novel catalytic technology with the parameters obtained during regression analysis to conclude that the cost factor for the catalyst is 0.0062-0.04759 US $ per barrel. PMID:18541367

  15. 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.

  16. Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation.

    PubMed

    Koch, Hanna; Galushko, Alexander; Albertsen, Mads; Schintlmeister, Arno; Gruber-Dorninger, Christiane; Lücker, Sebastian; Pelletier, Eric; Le Paslier, Denis; Spieck, Eva; Richter, Andreas; Nielsen, Per H; Wagner, Michael; Daims, Holger

    2014-08-29

    The bacterial oxidation of nitrite to nitrate is a key process of the biogeochemical nitrogen cycle. Nitrite-oxidizing bacteria are considered a highly specialized functional group, which depends on the supply of nitrite from other microorganisms and whose distribution strictly correlates with nitrification in the environment and in wastewater treatment plants. On the basis of genomics, physiological experiments, and single-cell analyses, we show that Nitrospira moscoviensis, which represents a widely distributed lineage of nitrite-oxidizing bacteria, has the genetic inventory to utilize hydrogen (H2) as an alternative energy source for aerobic respiration and grows on H2 without nitrite. CO2 fixation occurred with H2 as the sole electron donor. Our results demonstrate a chemolithoautotrophic lifestyle of nitrite-oxidizing bacteria outside the nitrogen cycle, suggesting greater ecological flexibility than previously assumed.

  17. 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.

  18. Metal-Catalyzed Oxidation and Photo-oxidation of Glucagon.

    PubMed

    Zhang, Jian

    2016-08-01

    The oxidation of glucagon by the H2O2/Cu(2+) system and by simulated sunlight was studied using HPLC-MS methodologies. It was found that copper ion-catalyzed oxidation is much faster in the residue 1-12 region than in photo-oxidation, but it is slower than photo-oxidation in the residue 18-29 region. This difference is due to the unique feature of the primary sequence of glucagon. The residue 1-12 region contains His-1 and Asp-9 that can bind to Cu(2+) ions and catalyze the oxidation of His-1 and Tyr-10, while the residue 18-29 region lacks these charged residues near the liable Met-27 and Trp-25 and hence no catalysis by the neighboring groups occurs. Fragment (residue 13-17) was more stable than the other regions of the peptide toward photo-oxidation because it contains only one oxidizable residue, Tyr-13. These findings may help explain the mechanism of action of glucagon and provide some hints for the development of effective anti-diabetic drug molecules and stable glucagon formulations.

  19. 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.

  20. Investigation of Mixed Oxide Catalysts for NO Oxidation

    SciTech Connect

    Szanyi, Janos; Karim, Ayman M.; Pederson, Larry R.; Kwak, Ja Hun; Mei, Donghai; Tran, Diana N.; Herling, Darrell R.; Muntean, George G.; Peden, Charles HF; Howden, Ken; Qi, Gongshin; Li, Wei

    2014-12-09

    The oxidation of engine-generated NO to NO2 is an important step in the reduction of NOx in lean engine exhaust because NO2 is required for the performance of the LNT technology [2], and it enhances the activities of ammonia selective catalytic reduction (SCR) catalysts [1]. In particular, for SCR catalysts an NO:NO2 ratio of 1:1 is most effective for NOx reduction, whereas for LNT catalysts, NO must be oxidized to NO2 before adsorption on the storage components. However, NO2 typically constitutes less than 10% of NOx in lean exhaust, so catalytic oxidation of NO is essential. Platinum has been found to be especially active for NO oxidation, and is widely used in DOC and LNT catalysts. However, because of the high cost and poor thermal durability of Pt-based catalysts, there is substantial interest in the development of alternatives. The objective of this project, in collaboration with partner General Motors, is to develop mixed metal oxide catalysts for NO oxidation, enabling lower precious metal usage in emission control systems. [1] M. Koebel, G. Madia, and M. Elsener, Catalysis Today 73, 239 (2002). [2] C. H. Kim, G. S. Qi, K. Dahlberg, and W. Li, Science 327, 1624 (2010).