Electrochemical decomposition of PPCPs on hydrophobic Ti/SnO2-Sb/La-PbO2 anodes: Relationship between surface hydrophobicity and decomposition performance

Abstract The global detection and potential harm of pharmaceuticals and personal care products (PPCPs) call for the effective decomposition technology. In this study, the modified β-PbO2 anodes with different hydrophobicity (Ti/SnO2-Sb/La-PbO2, Ti/SnO2-Sb/La-PbO2-PTFE and Ti/SnO2-Sb/La-PbO2-PVDF) were prepared to decompose aqueous PPCPs, i.e. isoniazid, methotrexate, carbamazepine, sulfamethoxazole and ibuprofen. PTFE and PVDF modification improved the physical property, electrochemical property, stability and safety of β-PbO2 electrode. Moreover, Ti/SnO2-Sb/La-PbO2-PVDF had the highest oxygen evolution potential (1.95 V vs. SCE), the largest electroactive area (88.85 cm2), the highest HO• production rate (10.44 mM min−1 m−2) and the best degradation performance for all the five PPCPs. The hydrophobic surface increased the proportion of free HO•, resulting in higher radical utilization rate and better degradation performance. The excessive hydrophobicity could decrease the degradation performance of PPCPs with high log Kow due to the relatively large hydrophobic force zone. Furthermore, the hydrophobicity enhanced the mineralization (current) efficiency of isoniazid, and its electrochemical degradation mechanism on Ti/SnO2-Sb/La-PbO2-PVDF was thoroughly proposed. These results demonstrated that Ti/SnO2-Sb/La-PbO2-PVDF anode exhibited a good application prospect in treating wastewater containing PPCPs.