Topic
Hydrogen peroxide
About: Hydrogen peroxide is a research topic. Over the lifetime, 42583 publications have been published within this topic receiving 1043732 citations. The topic is also known as: H2O2 & dioxidane.
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TL;DR: The inability of reagents to prevent losses of soluble metal in these experiments strongly suggests that a proportion of the metal actually released from a sediment sample during an extraction will be readsorbed, which may lead to serious misinterpretation of extraction data.
Abstract: w The adsorption of Cu, Pb, and Cd from selected extractant solutions, onto uncontaminated river sediments, has been investigated under typical extraction conditions. Significant adsqrption of added metal was found to occur during overnight extraction with dilute HC1 (pH >1.5), 0.1 M hydroxylamine hydrochloride (pH 2), 0.1 M sodium citrate (pH 4.6), 1 M ammonium acetate, 10% sodium citrate-1% sodium dithionite, and 25% acetic acid. Adsorption also occurred during a hydrogen peroxide digestion procedure. The inability of reagents to prevent losses of soluble metal in these experiments strongly suggests that a proportion of the metal actually released from a sediment sample during an extraction will be readsorbed. This may lead to serious misinterpretation of extraction data because the metal concentrations determined in the extract do not represent metal levels in the sediment fractions attacked.
208 citations
TL;DR: The importance of O2- in carrying the reaction chains was shown by the inhibition of phenylhydrazine oxidation by superoxide dismutase, and a mechanism was proposed which is consistent with the data.
Abstract: The oxidation of phenylhydrazine in buffered aqueous solutions is a complex process involving several intermediates. It can be initiated by metal cations, such as Cu2+; in which case EDTA acts as an inhibitor. It can also be intiated by oxyhemoglobin; in which case chelating agents do not interfere. Superoxide radical is both a product of this reaction and a chain propagator. The formation of O2- could be demonstrated in terms of a reduction of nitroblue tetrazolium, which was prevented by superoxide dismutase. The importance of O2- in carrying the reaction chains was shown by the inhibition of phenylhydrazine oxidation by superoxide dismutase. Hydrogen peroxide accumulated during the reaction and could be detected with catalase. The progress of this oxidation could be monitored in terms of oxygen consumption and by following increases in absorbance at 280 or 320 nm. The oxidation was markedly autocatalytic and superoxide dismutase had the effect of extending the lag period. The absorbance at 280 nm was due to an intermediate which first accumulated and was then consumed. This intermediate appears to be benzendiazonium ion. The absorbance at 320 nm was due to a stable product, which was not identified. The time course of oxygen consumption paralleled the increase in absorbance at 320 nm and lagged behind the changes at 280 nm. Exogenous benzenediazonium ion accelerated the oxidation of phenylhydrazine and eliminated the lag phase. Benzenediazonium ion must therefore react with phenylhydrazine to produce a very reactive intermediate, possibly phenyldiazene. A mechanism was proposed which is consistent with the data. The intermediates and products of the oxidation of phenylhydrazine include superoxide radical, hydrogen peroxide, phenylhydrazyl radical, phenyldiazene, and benzenediazonium ion. This is a minimal list: others remain to be detected and identified. It appears likely that the diverse biological effects of phenylhydrazine are largely due to the reactivities of these intermediates and products.
207 citations
TL;DR: A kinetic model of the process, which was developed based on H 2 O 2 /UV-induced radical oxidation of organic compounds, was successfully verified in pure water as well as in synthetic solutions.
Abstract: This paper describes a study of a chemical oxidation process involving simultaneous application of hydrogen peroxide solution and ultraviolet light (H 2 O 2 /UV)for removal of organic pollutants from aqueous solution. The process was investigated experimentally in a continuous-flow stirred tank reactor (CSTR) under various operational conditions, i.e., H 2 O 2 dosage, UV light intensity, and liquid residence time. Synthetic solutions of a model organic compound, n-chlorobutane (BuCI), were oxidized at various pH and in the presence of various amounts of humic material and carbonate/bicarbonate ions in order to examine the effect of water quality on the process efficiency. A kinetic model of the process, which was developed based on H 2 O 2 /UV-induced radical oxidation of organic compounds, was successfully verified in pure water as well as in synthetic solutions.
207 citations
TL;DR: The results suggest that the injection of BPA induces overproduction of hydrogen peroxide in the mouse organs and the decrease of GSH and the increase of GSSG may be caused by the hydroxy radical.
207 citations
TL;DR: The complete reduction of molecular oxygen to water requires four electrons and is catalyzed by cytochrome oxidase in aerobic bacteria and mitochondria, but 1% to 3% of all oxygen consumed by respiration is inevitably reduced to superoxide radicals and hydrogen peroxide.
Abstract: The complete reduction of molecular oxygen to water requires four electrons and is catalyzed by cytochrome oxidase in aerobic bacteria and mitochondria. However, 1% to 3% of all oxygen consumed by respiration is inevitably reduced to superoxide radicals and hydrogen peroxide (H2O2). These and other
207 citations