Environment-friendly and efficient electrochemical degradation of sulfamethoxazole using reduced TiO2 nanotube arrays-based Ti membrane coated with Sb-SnO2

This study focused on the preparation, characterization, and sulfamethoxazole (SMX) removal performance of the SnO2-coated reactive electrochemical membrane (REM). This REM was fabricated by loading SnO2 on the reduced TiO2 nanotube arrays (RTNA)-based Ti membrane (TM). Regarding the dopant for SnO2, Sb was more effective in boosting the electrocatalytic activity than Bi, and the energy consumption for Sb-SnO2-coated REM (TM/RTNA/ATO) was lower than Bi-SnO2-coated REM (TM/RTNA/BTO). As for the internal layer, RTNA provided TM/RTNA/ATO with more electroactive surface areas and prolonged the service lifetime. Compared with batch mode, the SMX removal efficiency in flow-through mode was increased up to 8.4-fold. The SMX degradation performances were also affected by fluid velocity, current density, initial SMX concentration, and electrolyte concentration. The synergistic effects of •OH oxidation and direct electron transfer were responsible for the effective removal of SMX. TM/RTNA/ATO was proved to be stable and durable by multi-cycle and accelerated lifetime tests. Its extensive applicability was verified with high removal efficiencies of SMX in the surface water and wastewater effluent. These results demonstrate the promise of TM/RTNA/ATO for water treatment applications.