Volmer mechanism evaluation

The electrochemical hydrogen permeation technique has proved to be a valuable tool in the study of these reaction mechanisms. This is mainly due to the ability to estimate the amount of an intermediate (Hads) in the reaction scheme. Such studies have been presented, for example, by Devanathan and Stachurski, by Bockris et and by Iyer et The applicability of the Volmer-Tafel reaction scheme can be evaluated by considering the kinetic expressions for reactions (22) and (23), together with equilibrium in the absorption process (25)... 

In fact, quenching effects can be evaluated and linearized through classic Stem-Volmer plots. Rate constants responsible for dechlorination, decay of triplets, and quenching can be estimated according to a proposed mechanism. A Stern-Volmer analysis of photochemical kinetics postulates that a reaction mechanism involves a competition between unimolecular decay of pollutant in the excited state, D, and a bimolecular quenching reaction involving D and the quencher, Q (Turro N.J.. 1978). The kinetics are modeled with the steady-state approximation, where the excited intermediate is assumed to exist at a steady-state concentration ... 

The effect of humic materials on the photolytic micellar system was evaluated in DR s photodegradation. DR solubilized within Tween 80 micellar solution with or without humic materials was determined. In order to calculate the quantum yield, the molar absorptivity of DR was determined by spectrophotometry. The determination of the quantum yield and reaction rates was examined through a pseudo first-order decay rate expression. Quenching and catalytic effects resulting from the humic substances were examined through Stem-Volmer analysis. A reaction mechanism of photolytic decay of DR solubilized within surfactant micelles in the presence of various amount of humic materials was proposed for this purpose. The effect of high and low concentration of humic materials has been accounted for by a designed model. 

For charge transfer leading to a fluorescent exciplex, aU rate constants can be evaluated from the fluorescence decays, but particular attention should be paid to the possibility of occurrence of (1) transient effects, (2) the harpoon mechanism [70] (the electron goes first and then the exciplex is formed) and (3) ground-state charge-transfer complexes. All these phenomena lead to deviations from doubleexponential decays and/or differences between Stem-Volmer plots obtained from time-resolved (tq/t vs [Q]) and steady-state (Iq// vs [Q]) measurements. 

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