Hydrogen peroxide, decomposition

As the temperature is increased through the NTC zone, the contribution of alkylperoxy radicals falls. Littie alkyl hydroperoxide is made and hydrogen peroxide decomposition makes a greater contribution to radical generation. Eventually the rate goes through a minimum. At this point, reaction 2 is highly displaced to the left and alkyl radicals are the dominant radical species. 

The mechanism and rate of hydrogen peroxide decomposition depend on many factors, including temperature, pH, presence or absence of a catalyst (7—10), such as metal ions, oxides, and hydroxides etc. Some common metal ions that actively support homogeneous catalysis of the decomposition include ferrous, ferric, cuprous, cupric, chromate, dichromate, molybdate, tungstate, and vanadate. For combinations, such as iron and... 

Metal-ion catalysis of hydrogen peroxide decomposition can generate perhydroxyl and hydroxyl free radicals as in Scheme 10.26 [235]. The catalytic effects of Fe2+ and Fe3+ ions are found to be similar [235]. It is not necessary for the active catalyst to be dissolved [237], as rust particles can be a prime cause of local damage. The degradative free-radical reaction competes with the bleaching reaction, as illustrated in Scheme 10.27 [237]. Two adverse consequences arise from the presence of free radicals ... 

The parameter most commonly monitored in this research is the extent of hydrogen peroxide decomposition. Measurement of tensile strength and/or the degree of polymerisation can be useful indicators of fibre damage. The effect of iron(III) ion concentration in accelerating the rate of peroxide decomposition is shown in Figure 10.23,... 

Figure 10.23 Effect of Fe(m) ion concentration on rate of hydrogen peroxide decomposition in absence of substrate [237]. Initial concentration 2.9 g/l H202, Sodium silicate 5 g/l, Magnesium sulphate 0.2 g/l, 95 °C, pH 12...

The catalysis of hydrogen peroxide decomposition by iron ions occupies a special place in redox catalysis. This was precisely the reaction for which the concept of redox cyclic reactions as the basis for this type of catalysis was formulated [10-13]. The detailed study of the steps of this process provided a series of valuable data on the mechanism of redox catalysis [14-17]. The catalytic decomposition of H202 is an important reaction in the system of processes that occur in the organism [18-22]. 

Fig. 18b.9. Example cychc voltammograms due to (a) multi-electron transfer redox reaction two-step reduction of methyl viologen MV2++e = MV++e = MV. (b) ferrocene confined as covalently attached surface-modified electroactive species—peaks show no diffusion tail, (c) follow-up chemical reaction A and C are electroactive, C is produced from B through irreversible chemical conversion of B, and (d) electrocatalysis of hydrogen peroxide decomposition by phosphomolybdic acid adsorbed on a graphite electrode.

Klais, O. (1993). "Hydrogen Peroxide Decomposition in the Presence of Organic Material. A Case Study." Thermochimica Acta 225, 213-22. 

The superoxide anion radical and hydrogen peroxide are not particularly harmful to cells. It is the product of hydrogen peroxide decomposition, the hydroxyl radical (HO ), that is responsible for most of the cytotoxicity of oxygen radicals. The reaction can he catalyzed hy several transition metals, including copper, manganese, cohalt, and iron, of which iron is the most ahimdant in the human body (Reaction 2 also called the Fenton reaction). To avoid iron-catalyzed reactions, iron is transported and stored chiefly as Fe(III), although redox active iron can be formed in oxidative reactions, and Fe(III) can be reduced by semiquinone radicals (Reaction 3). 

DHAP can be prepared by oxidation of L-glycerol-3-phosphate (L- G3P) catalyzed by glycerophosphate oxidase, coupled with hydrogen peroxide decomposition in the presence of catalase (Scheme 4.5) [14]. More recently, this synthetic route has... 

The total decomposition of hydrogen peroxide by the action of hydrogen ions was measured iodometrically in the absence of oxygen. The rate of hydrogen peroxide decomposition was found to be... 

If, as a result of the presence of some impurities in a vessel containing hydrogen peroxide, decomposition is hastened, it is advisable to add an additional quantity of stabilizer, i.e. phosphoric acid. If this proves inadequate, then, according to Shanley and Greenspan [31], it is necessary to dilute the hydrogen peroxide with water to 67 % concentration when it is no longer dangerous, otherwise, violent decomposition may occur and the container may blow up. 

Table III. Hydrogen Peroxide Decomposition by a Marine Bacterium Vibrio alginolyticus Culture...

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