Electrocatalytic Oxidation of Sulfite on a Cobalt Pentacyanonitrosylferrate Film Modified Glassy Carbon Electrode

The electrocatalytic oxidation of sulfite has been studied on the cobalt pentacyanonitrosylferrate modified glassy carbon electrode (CoPCNF). The CoPCNF films on the glassy carbon electrodes show an excellent electrocatalytic activity toward the oxidation of sulfite in 0.5 M KNO3. The kinetics of the catalytic reaction was investigated by using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry. The average value of the rate constant, K, for the catalytic reaction and the diffusion coefficient, D, were evaluated by different approaches for sulfite and found to be 2.9×102 M−1s−1 and 4.6×10−6 cm2s−1, respectively. At a fixed potential under hydrodynamic conditions (stirred solutions), the oxidation current is proportional to the sulfite concentration and the calibration plot was linear over the concentration range 5×10−6–1×10−4 M. The detection limit of the method is 3×10−6 M., low enough for the trace sulfite determination.