A Study on the Anodic Oxidation of Iodide-Mediated Sulfur Dioxide Solution

A potent iodynamic method was used to invest igate the catalytic effect of potass ium iodide on the anodic oxidat ion of sul fur d iox ide solution. The catalytic depolar izat ion effects of potass ium iodide are between 0.25 and 0.5V, depend ing on e lect rode mater ia ls and cur rent densi t ies. The e lect rocata lyt ic ox idat ion behav iors are d i f ferent at the p la t inum and graphi te e lectrodes and are affected by the ensu ing chemica l react ions. At low electrode potent ia l iodide ions are init ial ly oxidized to iodine and this is fol lowed by the chemica l react ion of iodine wi th sulfur dioxide. At h igh electrode potent ia l the e lectrochemica l ox idat ion of iodide progresses to iodate and this is fol lowed by the chemica l react ion of iodate with sul fur dioxide. The iodide ions regenerated from the chemica l react ion near the electrode surface are avai lable again for ox idat ion w i thout a supply of iodide ion f rom the bu lk solution. The e lec t rochemica l ox idat ion of su l fur d iox ide has at-t rac ted a t tent ion i energy generat ion, hydrogen pro-duct ion, sod ium sul fate electrolysis, and e lec t rowinn ing of su l f ide ores. A l though many s tud ies were devoted t the anod ic ox idat ion f su l fu r d iox ide (1-5), many ques-t ions assoc ia ted w i th the ox idat ion mechan ism and th