Enhancing degradation of sulfamethoxazole by layered double hydroxide/carbon nanotubes catalyst via synergistic effect of photocatalysis/persulfate activation.

A CoMn-LDHs and carbon nanotube (CoMn-LDHs/CNT) composite catalyst was constructed for permonosulfate (PMS) activation and degrading sulfamethoxazole (SMX) under Vis light irradiation. The introduction of CNTs into CoMn-LDHs facilitate the exciton dissociation and carrier migration, and the e- and h+ were readily separated from CoMn-LDHs/CNT in the photocatalysis process, which promoted the production rate of reactive oxygen species (ROS), so the CoMn-LDHs + Vis + PMS system exhibited better activity with an SMX degradation ratio of 61.25% than those of CoMn-LDHs + Vis system (42.30%) and CoMn-LDHs + PMS system (48.30%). After 10 cycles, the degradation rate of SMX only decreased by 7.16%, indicating the good reusability of the CoMn-LDHs/CNTs catalyst. The results of electron paramagnetic resonance (EPR) analysis and radical quenching experiments demonstrated that that the SO played crucial role for SMX removal in CoMn-LDHs/CNTs + Vis + PMS system, and both e and h made an important contribution to activating PMS to produce ROS. Overall, this work provided an excellent catalyst for photo-assisted PMS activation and suggested the activation mechanism for organic pollutant remediation.