Electrochemical Ozone Production Coupled with Activated Peroxymonosulfate for Efficient Degradation of Emerging Contaminants

Electrochemical ozone production (EOP) is a promising method for water treatment. Nonetheless, the undiversified active species and the selective oxidation of O3 call for the development of coupling technologies to expand its processing scope. Herein, a system that coupled EOP with peroxymonosulfate (PMS) activation was constructed using Cu–Ni-doped Sb–SnO2 (CuNi-ATO) as the anode, whose performance and mechanism for the degradation of emerging contaminants (ECs) were investigated for the first time. The CuNi-ATO/PMS system achieved nearly 100% removal of metronidazole (MNZ) within 30 min under a current density of 10 mA cm–2, with a pseudo-first-order rate constant of up to 0.14 min–1. SO4•–, •OH, 1O2, and O2•– were identified and measured during the degradation process, where 1O2 as the dominant active species contributed 58.9% to MNZ degradation, while the radicals contributed to the majority of the rest. Additionally, the CuNi-ATO/PMS system showed excellent performance in removing different types of ECs via both radical and nonradical pathways. It was confirmed that O3 played a dominant role in activating PMS with the exclusion of the contribution from electrochemistry. Benefiting from the abundant active species, the CuNi-ATO/PMS system displayed satisfactory anti-interference ability for the degradation of MNZ in complex matrices and was competent to mineralize the real wastewater efficiently.