Electrochemical oxidation of iodide in aqueous solution

Abstract

Electrochemical oxidation of iodide on DSA (Ti/RuO2) anode was investigated in laboratory cell and semi-industrial electrochemical reactor. Anodic polarization curves in the laboratory cell were obtained in solutions contained 0.10, 0.25 and 0.40 mol dm(-3) KI in order to determined current densities for electrolysis in the semi-industrial electrochemical reactor. Parameters of the electrolysis were estimated using semi-industrial electrochemical reactor in which concentration of KI and current density were varied. pH and reactor voltage, were measured as a function of time, as well. The electrolysis was carried out until stationary concentration of equivalent iodine was reached. It was concluded that optimal electrolysis conditions based on current efficiency, concentrations of equivalent iodine, and the other parameters, was achieved in solution contained 0.40 mol dm(-3) KI and with current density of 10 mA cm(-2). Based on the theoretical analysis of the iodine-iodide-water equilibria, it was concluded that at pH 11.6 main electrolysis products were triiodide, hypoiodite and IOH2-.