The radical and non-radical oxidation mechanism of electrochemically activated persulfate process on different cathodes in divided and undivided cell.

Electrochemically activated persulfate (PS) employing stainless steel (SS), carbon felt (CF) and carbon black modified CF (CB-CF) as the cathode, in the divided and undivided cell, respectively, for degradation of atrazine (ATZ) was first investigated using novel B, Co-doped TiO nanotubes (B, Co-TNT) anode. In undivided cell, ATZ degradation was followed the order of CF<CB-CF<SS. The main radical for ATZ removal in SS and CF system was OH, while on CB-CF cathode, it was the comprehensive contribution of OH and SO. OH in SS system was more inclined to free OH, while in CF and CB-CF systems it was more likely to be surface OH. In divided anode cell, OH was responsible for ATZ degradation in all three cathodes system. However, in divided cathode cell, OH played a major role for ATZ degradation in SS cathode system. In CF and CB-CF cathode systems, the ATZ degradation was the comprehensive effect of OH and SO with the contribution of OH and SO was 91.7%, 8.3%, and 96.3%, 3.6%, respectively. The quenching studies showed that non-radical oxidation occurred in anode chamber in the presence of PS. Besides, the intermediates in divided and undivided cell were detected by LC-MS, and the possible degradation pathway was proposed.