RESEARCH OF KINETICS AND MECHANISM OF ELECTROOXIDATION-REDUCTION OF SULPHUR IN ALKALINE SOLUTIONS

In this work kinetics and mechanism of electrode processes of oxidation-reduction of sulphur, proceeding on electro-conductive sulphur-graphite electrode in alkaline solutions by potentiodynamic method have been studied. In order to elucidate the mechanism of electrode processes occurring in the polarization by alternate currents on sulphur-graphite electrode, the anode-cathode and cathode-anode cyclic polarizing curves, anodic polarising curves were removed. According to polarizing measurements data, kinetic parameters, such as coefficient ionstransfer (alpha), coefficients of diffusion (D), heterogeneous constants of velocity (k(s)), effective energy of activation of process (A(ef)) were calculated. The analysis of results and measurements of the calculated kinetic parametres of electrode processes has shown that sulphur-discharge ionization in alkaline solution proceeds in two successive stages and is quasi-reversible process. Final influence on velocity of process renders the velocity of sulphur oxidation to sulfite ions, being slower and having, possibly, mixed nature of the control. In the field of potentials between the cathodic reduction of sulphur and its anodic dissolution, sulphur-graphite electrode is stable in investigated alkaline solutions and it can have oxidation and reduction processes involving sulphur-containing ions.