Surface-bound sulfate radical-dominated degradation of sulfamethoxazole in the CuFeAl-LDH/peroxymonosulfate system: The abundant hydroxyl groups enhancing efficiency mechanism

In this study, a fast and efficient Cu2Fe0.5Al0.5-LDH/PMS water purification system was constructed to degrade sulfamethoxazole (SMX). The optimized Cu2Fe0.5Al0.5-LDH/PMS reaction system degraded 50% SMX for only 0.5 min, and 98.25% SMX for 10 min. The advanced characterization techniques proved that the abundant hydroxyl groups of Cu2Fe0.5Al0.5-LDH can form ≡M−(O)OSO3− complexes with PMS, resulting in reactive oxygen species (ROS) and promoting SMX degradation. Moreover, the electron transfer between the active bimetallic components played a synergistic role in the generation of ROS species. Compared with the electron transfer degradation mechanism, ROS mechanism contributed more to SMX degradation, in which surface-bound SO4− was the dominated active species. The possible degradation pathway and intermediate toxicity of SMX were proposed. This work provided a strategy to fully explore the catalytic degradation mechanism of heterogeneous catalysts in wastewater purification.