Electrochemical oxidation of humic acid at the antimony- and nickel-doped tin oxide electrode

This work investigated the degradation of humic acid (HA) in aqueous solution by electrochemical oxidation with Antimony- and Nickel-doped Tin oxide electrode (Ni-Sb-SnO₂/Ti electrode) as the anode. Initial concentrations of HA ranged from 3 to 9 mg·L^-1. Under such a concentration scope, the degradation of HA was a mass transfer controlled process. Degradation rate increased with the increase of HA initial concentration. Test on the effect of tert-butanol revealed that ·OH played an important role in the oxidation of HA. The absence of cation Ca²⁺ was beneficial to HA degradation, which suggested that both indirect and direct electrolyze happened during the whole electrochemical oxidation process. Alkaly (pH = 12) and neutral (pH = 7) conditions were benefical to HA degradation.