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Journal of Contaminant Hydrology Apr 2017The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB...
The methods and results of the first field-scale demonstration of polymer-amended in situ chemical oxidation (PA-ISCO) are presented. The demonstration took place at MCB CAMLEJ (Marine Corps Base, Camp Lejeune) Operable Unit (OU) 15, Site 88, in Camp Lejeune, North Carolina between October and December 2010. PA-ISCO was developed as an alternative treatment approach that utilizes viscosity-modified fluids to improve the in situ delivery and distribution (i.e. sweep-efficiency) of chemical oxidants within texturally heterogeneous contaminated aquifers. The enhanced viscosity of the fluid mitigates the effects of preferential flows, improving sweep-efficiency and enhancing the subsurface contact between the injected oxidant and the target contamination within the treatment zone. The PA-ISCO fluid formulation used in this demonstration included sodium permanganate as oxidant, xanthan gum biopolymer as a shear-thinning viscosifier, and sodium hexametaphosphate (SHMP) as an anti-coagulant. It was the goal of this demonstration to validate the utility of PA-ISCO within a heterogeneous aquifer. An approximate 100% improvement in sweep-efficiency was achieved for the PA-ISCO fluid, as compared to a permanganate-only injection within an adjacent control plot.
Topics: Environmental Restoration and Remediation; Groundwater; Manganese Compounds; Models, Theoretical; North Carolina; Oxidants; Oxidation-Reduction; Oxides; Phosphates; Polymers; Seasons; Sodium Compounds; Viscosity; Water Pollutants, Chemical
PubMed: 28341384
DOI: 10.1016/j.jconhyd.2017.03.001 -
Chemosphere Aug 2013Oxidation is well-known process of transforming natural organic matter during the treatment of drinking water. Chlorine, ozone, and chlorine dioxide are common oxidants...
Oxidation is well-known process of transforming natural organic matter during the treatment of drinking water. Chlorine, ozone, and chlorine dioxide are common oxidants used in water treatment technologies for this purpose. We studied the influence of different doses of these oxidants on by-products formation and changes in biodegradable dissolved organic carbon (BDOC) and molecular weight distribution (MWD) of fulvic acids (FA) with different BDOC content. Chlorination did not significantly change the MWD of FA and disinfection by-products formation. However, higher molecular weight compounds, than those in the initial FA, were formed. It could be a result of chlorine substitution into the FA structure. Chlorine dioxide oxidized FA stronger than chlorine. During ozonation of FA, we found the highest increase of BDOD due to the formation of a high amount of organic acids and aldehydes. FA molecules were transformed into a more biodegradable form. Ozonation is the most preferable process among those observed for pre-treatment of FA before biofiltration.
Topics: Benzopyrans; Biodegradation, Environmental; Carbon; Chlorine; Chlorine Compounds; Drinking Water; Halogenation; Oxidants; Oxidation-Reduction; Oxides; Ozone; Water Purification
PubMed: 23746389
DOI: 10.1016/j.chemosphere.2013.05.046 -
Journal of the American Chemical Society Aug 2008The oxidation of alkanes by various peroxides ((t)BuOOH, H2O2, PhCH2C(CH3)2OOH) is efficiently catalyzed by [Os(VI)(N)Cl4](-)/Lewis acid (FeCl3 or Sc(OTf)3) in...
The oxidation of alkanes by various peroxides ((t)BuOOH, H2O2, PhCH2C(CH3)2OOH) is efficiently catalyzed by [Os(VI)(N)Cl4](-)/Lewis acid (FeCl3 or Sc(OTf)3) in CH2Cl2/CH3CO2H to give alcohols and ketones. Oxidations occur rapidly at ambient conditions, and excellent yields and turnover numbers of over 7500 and 1000 can be achieved in the oxidation of cyclohexane with (t)BuOOH and H2O2, respectively. In particular, this catalytic system can utilize PhCH2C(CH3)2OOH (MPPH) efficiently as the terminal oxidant; good yields of cyclohexanol and cyclohexanone (>70%) and MPPOH (>90%) are obtained in the oxidation of cyclohexane. This suggests that the mechanism does not involve alkoxy radicals derived from homolytic cleavage of MPPH but is consistent with heterolytic cleavage of MPPH to produce a metal-based active intermediate. The following evidence also shows that no free alkyl radicals are produced in the catalytic oxidation of alkanes: (1) The product yields and distributions are only slightly affected by the presence of O2. (2) Addition of BrCCl3 does not affect the yields of cyclohexanol and cyclohexanone in the oxidation of cyclohexane. (3) A complete retention of stereochemistry occurs in the hydroxylation of cis- and trans-1,2-dimethylcyclohexane. The proposed mechanism involves initial O-atom transfer from ROOH to [Os(VI)(N)Cl4](-)/Lewis acid to generate [Os(VIII)(N)(O)Cl4](-)/Lewis acid, which then oxidizes alkanes via H-atom abstraction.
Topics: Alkanes; Catalysis; Organometallic Compounds; Osmium; Oxidants; Oxidation-Reduction; Peroxides
PubMed: 18642814
DOI: 10.1021/ja802625e -
Dalton Transactions (Cambridge, England... Mar 2010Controlled oxidation of organic sulfides to sulfoxides under ambient conditions has been achieved by a series of titanium isopropoxide complexes that use environmentally...
Controlled oxidation of organic sulfides to sulfoxides under ambient conditions by a series of titanium isopropoxide complexes using environmentally benign H2O2 as an oxidant.
Controlled oxidation of organic sulfides to sulfoxides under ambient conditions has been achieved by a series of titanium isopropoxide complexes that use environmentally benign H(2)O(2) as a primary oxidant. Specifically, the [N,N'-bis(2-oxo-3-R(1)-5-R(2)-phenylmethyl)-N,N'-bis(methylene-R(3))-ethylenediamine]Ti(O(i)Pr)(2) [R(1) = t-Bu, R(2) = Me, R(3) = C(7)H(5)O(2) (1b); R(1) = R(2) = t-Bu, R(3) = C(7)H(5)O(2) (2b); R(1) = R(2) = Cl, R(3) = C(7)H(5)O(2) (3b) and R(1) = R(2) = Cl, R(3) = C(6)H(5) (4b)] complexes efficiently catalyzed the sulfoxidation reactions of organic sulfides to sulfoxides at room temperature within 30 min of the reaction time using aqueous H(2)O(2) as an oxidant. A mechanistic pathway, modeled using density functional theory for a representative thioanisole substrate catalyzed by 4b, suggested that the reaction proceeds via a titanium peroxo intermediate 4c', which displays an activation barrier of 22.5 kcal mol(-1) (DeltaG(++)) for the overall catalytic cycle in undergoing an attack by the S atom of the thioanisole substrate at its sigma*-orbital of the peroxo moiety. The formation of the titanium peroxo intermediate was experimentally corroborated by a mild ionization atmospheric pressure chemical ionization (APCI) mass spectrometric technique.
Topics: Crystallography, X-Ray; Hydrogen Peroxide; Models, Molecular; Molecular Structure; Organometallic Compounds; Oxidants; Oxidation-Reduction; Stereoisomerism; Sulfhydryl Compounds
PubMed: 20162218
DOI: 10.1039/b921720g -
Water Research Nov 2010Arsenic is widespread in soils, water and air. In natural water the main forms are arsenite (As(III)) and arsenate (As(V)). The consumption of water containing high... (Comparative Study)
Comparative Study
Arsenic is widespread in soils, water and air. In natural water the main forms are arsenite (As(III)) and arsenate (As(V)). The consumption of water containing high concentration of arsenic produces serious effects on human health, like skin and lung cancer. In Italy, Legislative Decree 2001/31 reduced the limit of arsenic from 50 to 10 μg/L, in agreement with the European Directive 98/83/EC. As consequence, many drinking water treatment plant companies needed to upgrade the existing plants where arsenic was previously removed or to build up new plants for arsenic removal when this contaminant was not previously a critical parameter. Arsenic removal from water may occur through the precipitation with iron or aluminum salts, adsorption on iron hydroxide or granular activated alumina (AA), reverse osmosis and ion exchange (IE). Some of the above techniques, especially precipitation, adsorption with AA and IE, can reach good arsenic removal yields only if arsenic is oxidized. The aim of the present work is to investigate the efficiency of the oxidation of As(III) by means of four conventional oxidants (chlorine dioxide, sodium hypochlorite, potassium permanganate and monochloramine) with different test conditions: different type of water (demineralised and real water), different pH values (5.7-6-7 and 8) and different doses of chemicals. The arsenic oxidation yields were excellent with potassium permanganate, very good with hypochlorite and low with monochloramine. These results were observed both on demineralised and real water for all the tested reagents with the exception of chlorine dioxide that showed a better arsenic oxidation on real groundwater than demineralised water.
Topics: Arsenic; Chloramines; Chlorine Compounds; Hydrogen-Ion Concentration; Hypochlorous Acid; Oxidants; Oxidation-Reduction; Oxides; Potassium Permanganate; Water; Water Purification
PubMed: 20638704
DOI: 10.1016/j.watres.2010.06.032 -
FEBS Letters Jul 2010Oxidative protein folding in the luminal compartment of the endoplasmic reticulum is thought to be mediated by a proteinaceous electron relay system composed by PDI and... (Review)
Review
Oxidative protein folding in the luminal compartment of the endoplasmic reticulum is thought to be mediated by a proteinaceous electron relay system composed by PDI and ER oxidoreductin 1 (Ero1), transferring electrons from the cysteinyl residues of substrate proteins to oxygen. However, recent observations revealed that Ero1 isoforms are dispensable. Endoplasmic reticulum is known as a generator and accumulator of low molecular weight oxidants; some of them have already been shown to promote oxidative folding. On the basis of these observations a new theory of oxidative folding is proposed where the oxidative power is provided by the stochastic contribution of prooxidants.
Topics: Animals; Endoplasmic Reticulum; Models, Biological; Oxidants; Oxidation-Reduction; Oxides; Oxygen; Protein Folding; Protein Isoforms; Reactive Oxygen Species
PubMed: 20621831
DOI: 10.1016/j.febslet.2010.05.055 -
Journal of Neurochemistry Dec 1999Increased nitric oxide (NO) production has been implicated in many examples of neuronal injury such as the selective neurotoxicity of methamphetamine and... (Comparative Study)
Comparative Study
Increased nitric oxide (NO) production has been implicated in many examples of neuronal injury such as the selective neurotoxicity of methamphetamine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to dopaminergic cells, presumably through the generation of the potent oxidant peroxynitrite (ONOO). Dopamine (DA) is a reactive molecule that, when oxidized to DA quinone, can bind to and inactivate proteins through the sulfhydryl group of the amino acid cysteine. In this study, we sought to determine if ONOO could oxidize DA and participate in this process of protein modification. We measured the oxidation of the catecholamine by following the binding of [3H]DA to the sulfhydryl-rich protein alcohol dehydrogenase. Results showed that ONOO oxidized DA in a concentration- and pH-dependent manner. We confirmed that the resulting DA-protein conjugates were predominantly 5-cysteinyl-DA residues. In addition, it was observed that ONOO decomposition products such as nitrite were also effective at oxidizing DA. These data suggest that the generation of NO and subsequent formation of ONOO or nitrite may contribute to the selective vulnerability of dopaminergic neurons through the oxidation of DA and modification of protein.
Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Alcohol Dehydrogenase; Antioxidants; Apoptosis; Catalase; Chromatography, High Pressure Liquid; Dopamine; Hydrogen-Ion Concentration; Methamphetamine; Monophenol Monooxygenase; Nerve Tissue Proteins; Neurons; Nitrates; Nitric Oxide; Nitrites; Oxidants; Oxidation-Reduction; Parkinson Disease; Protein Binding; Sulfhydryl Compounds; Superoxide Dismutase
PubMed: 10582617
DOI: 10.1046/j.1471-4159.1999.0732546.x -
Journal of Hazardous Materials Jun 2010The activated carbon-MnO(2) catalyst has been prepared by the dipping-calcination method with activated carbon used as a carrier. The catalyst is used for...
The activated carbon-MnO(2) catalyst has been prepared by the dipping-calcination method with activated carbon used as a carrier. The catalyst is used for catalyzing/degrading simulated o-chlorophenol wastewater with chlorine dioxide as oxidant. The COD removal efficiency by catalytic oxidation is 93.5% at the condition of wastewater's COD is 2085 mg/l, the pH value is 1.2, the dosage of chlorine dioxide is 1000 mg/l, the dosage of activated carbon-MnO(2) catalyst is 6g by reacting 60 min. The COD removal efficiency by catalytic oxidation is great than that of chemical oxidation. The catalytic activity of the catalyst only decreased a small amount in terms of COD removal efficiency after using 11 times. The COD removal efficiency is 80-90% during the continuity wastewater treatment experiment, which indicates that the wastewater treatment process is practical. The FTIR spectra indicate that the active ingredient of manganese dioxide is linked with activated carbon by chemical bond, not merely mechanical blending.
Topics: Catalysis; Chlorine Compounds; Chlorophenols; Indicators and Reagents; Manganese Compounds; Oxidants; Oxidation-Reduction; Oxides; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Waste Disposal, Fluid; Water Purification
PubMed: 20149526
DOI: 10.1016/j.jhazmat.2010.01.125 -
Chemistry, An Asian Journal Sep 2006A protocol that adopts aqueous hydrogen peroxide as a terminal oxidant and [(Me3tacn)(CF3CO2)2Ru(III)(OH2)]CF3CO2 (1; Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane)...
A protocol that adopts aqueous hydrogen peroxide as a terminal oxidant and [(Me3tacn)(CF3CO2)2Ru(III)(OH2)]CF3CO2 (1; Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane) as a catalyst for oxidation of alkenes, alkynes, and alcohols to organic acids in over 80% yield is presented. For the oxidation of cyclohexene to adipic acid, the loading of 1 can be lowered to 0.1 mol %. On the one-mole scale, the oxidation of cyclohexene, cyclooctene, and 1-octanol with 1 mol % of 1 produced adipic acid (124 g, 85% yield), suberic acid (158 g, 91% yield), and 1-octanoic acid (129 g, 90% yield), respectively. The oxidative C=C bond-cleavage reaction proceeded through the formation of cis- and trans-diol intermediates, which were further oxidized to carboxylic acids via C-C bond cleavage.
Topics: Adipates; Alcohols; Alkenes; Alkynes; Carbon; Carboxylic Acids; Catalysis; Chemistry, Pharmaceutical; Cyclohexenes; Hydrogen Peroxide; Models, Chemical; Oxidants; Oxygen; Ruthenium
PubMed: 17441082
DOI: 10.1002/asia.200600091 -
The Biochemical Journal Mar 2006Eosinophil peroxidase is a haem enzyme of eosinophils that is implicated in oxidative tissue injury in asthma. It uses hydrogen peroxide to oxidize thiocyanate and...
Eosinophil peroxidase is a haem enzyme of eosinophils that is implicated in oxidative tissue injury in asthma. It uses hydrogen peroxide to oxidize thiocyanate and bromide to their respective hypohalous acids. Nitrite is also a substrate for eosinophil peroxidase. We have investigated the mechanisms by which the enzyme oxidizes nitrite. Nitrite was very effective at inhibiting hypothiocyanous acid ('cyanosulphenic acid') and hypobromous acid production. Spectral studies showed that nitrite reduced the enzyme to its compound II form, which is a redox intermediate containing Fe(IV) in the haem active site. Compound II does not oxidize thiocyanate or bromide. These results demonstrate that nitrite is readily oxidized by compound I, which contains Fe(V) at the active site. However, it reacts more slowly with compound II. The observed rate constant for reduction of compound II by nitrite was determined to be 5.6x10(3) M(-1) x s(-1). Eosinophils were at least 4-fold more effective at promoting nitration of a heptapeptide than neutrophils. This result is explained by our finding that nitrite reacts 10-fold faster with compound II of eosinophil peroxidase than with the analogous redox intermediate of myeloperoxidase. Nitration by eosinophils was increased 3-fold by superoxide dismutase, which indicates that superoxide interferes with nitration. We propose that at sites of eosinophilic inflammation, low concentrations of nitrite will retard oxidant production by eosinophil peroxidase, whereas at higher concentrations nitrogen dioxide will be a major oxidant formed by these cells. The efficiency of protein nitration will be decreased by the diffusion-controlled reaction of superoxide with nitrogen dioxide.
Topics: Eosinophil Peroxidase; Eosinophils; Humans; Hydrogen Peroxide; Neutrophils; Nitrates; Nitrites; Oxidants; Oxidation-Reduction; Substrate Specificity
PubMed: 16336215
DOI: 10.1042/BJ20051470