Electrochemistry of the oxidation of sulfite and bisulfite ions at a graphite surface: an overall approach

Abstract

An investigation of the electrochemical oxidation of sulfite and bisulfite ions dissolved in a sodium electrolyte solutions at a graphite surface was undertaken. The study relies upon linear voltammetry and the importance of the various oxidative processes occuring at the graphite surface, namely electrochemical of residual organic groups, carbon oxides and oxygen evolution, as well as the oxidation of tetravalent sulfur oxidation. The i—E curves relevant to bisulfite and the sulfite oxidation are modeled by the simple Butler—Volmer law for irreversible direct proceses even though the oxidation scheme has not yet been elucidated. Confidence intervals of the determined parameters, diffusion coefficient, exchange current density, and charge-transfer coefficient are estimated.