Analysis of the electrode kinetics of Ni(II) reduction in thiocyanate media on the dropping mercury electrode

摘要

A study of two prewaves of the Ni(II)-SCN- system was carried out under the experimental conditions when the influence of electroreduction of SCN- is negligible. Kinetics of Ni(II) reduction in thiocyanate media on the dropping mercury electrode was studied by DC Tast Polarography (DCTP) via determination of Koutecky's parameter chi; the influence of different variables was analyzed. The study of prewaves was performed using various polarographic techniques. Values of chi depend on the SCN- concentration, pH, ionic strength (Psi-effect) and on the nature of the supporting electrolyte. The number of electrons it, the transfer coefficient alpha, the stoichiometric number nu, Delta H-not equal, and Delta S-not equal were determined (compensation effect). The first prewave has character of a reaction in the solution, the second prewave is a surface process. Main features of both mechanisms are common: catalytic nature, one-electron step discharge and the rate-determining process between species of opposite charges. [References: 37]