Deactivation of complex formation by anodic oxidation on boron-doped diamond electrodes

The wastewater discharged from the plating process contains highly toxic transition metals. To decontaminate plating wastewater, we investigated the deactivation of complex formation via the anodic oxidation of three complexing agents - (ethylenediaminetetraacetic acid (EDTA), gluconic acid (GA), and triethanolamine (TEA)) - on a boron-doped diamond (BDD) electrode. The performance of the BDD electrode was compared with those of existing electrodes: a Pt electrode, an IrO2 electrode, and a PbO2 electrode. Compared with the Pt and IrO2 electrodes, the BDD electrode achieved higher deactivation rates of GA and TEA. Moreover, we investigated the decomposition products of the complexing agents and the variation in the total organic carbon content during the electrooxidation. The BDD electrode rapidly oxidized the formic acid generated as the decomposition product and achieved the complete mineralization of EDTA after 8 h of anodic oxidation and GA and TEA after 12 h. These results indicate that anodic oxidation on a BDD electrode is a suitable method for treating plating wastewater containing complexing agents.