Electrochemical behaviour of sodium dithionite at a platinum electrode and determination of diffusion coefficient in alkaline solution

The electrochemical behaviour of sodium dithionite at a platinum electrode has been investigated in this paper. Two oxidation waves of sodium dithionite were observed with formation of sulfite as a stable intermediate species. It has been found that the oxidation of sodium dithionite to sulfite, according to the first wave, is controlled by the rate of mass transport, the oxidation of sulfite to sulfate, however, is not purely controlled by transport phenomena. Using the ratio of the limiting currents of both oxidation waves it was possible to determine the diffusion coefficient of sodium dithionite by extrapolation to the small rotation rate of the platinum electrode. From the obtained results it is also advisable to make use of the first oxidation reaction for analytical purposes.