engleski

Square-wave voltammetry of a cathodic stripping reaction complicated by adsorption of the reacting ligand

A model of the cathodic stripping process of an insoluble mercuric salt precipitated on the mercury electrode surface and complicated by adsorption of the reacting ligand, is developed under conditions of square-wave voltammtry (SWV). The adsorption isotherm of the reacting ligand is supposed to be linear. Theoretical relationships between the properties of the SW response and the parameters of the redox reaction as well as SW excitation signal are analyzed. Both reversible and quasireversible redox reactions are considered. The phenomena such as quasireversible maxima and splitting of the SW peak are discussed. The theoreticla model is verified experimentally with the mercury/6-propyl-2-thiouracil system. The kinetic parametrs of the redox reaction of the mercury in the presence of 6-propyl-2-thiouracil in 1 mol dm3 KNO3 are estimated as follows: standard rate konstant ks = 25 +-5 s-1 and cathodic coefficient alfa = 0.6 +- 0.1. The adsorption constantof 6-propyl-2-thiouracil on the mercury surface in 1 mol dm-3 KNO3 is estimated to be in range: 0.1<-log(K/cm-1)<-1.2.

sqare-wave voltammetry; cathodic stripping; quasireversible redox reaction

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