Activation of persulfate by β-PDI/MIL-101(Fe) photocatalyst under visible light toward efficient degradation of sulfamethoxazole

Abstract

Recently, the removal of antibiotics from wastewater has become increasingly important. Advanced oxidation processes (AOPs) combining persulfate (PS) activation and photocatalysis have been proven as a promising strategy for antibiotics degradation. For the first time, the β-alanine modified perylene diimide derivative (β-PDI) and MIL-101(Fe) were selected to create novel Z-scheme photocatalysts (MPx) by simple milling method based on the electrostatic attraction. The optimal MP50/PS/vis system could remove 99.7 % of SMX within 6 min and the MP50 displayed great recyclability and sustainability. The persulfate as electron scavenger not only inhibited the recombination of photogenerated electron-hole pairs but also generated additional SO4•-, thereby improving the efficiency of SMX degradation. The removal of SMX was simultaneously dependent on radicals (h+, O2•-, SO4•-, and •OH) and non-radical (1O2) pathways, and it is noteworthy that h+ played a major role. LC-MS was applied to investigate the degradation pathways and intermediates of SMX, their toxicities were further studied and the results showed that the MP50/PS/vis system was successful in reducing its biotoxicity and the risk of inducing potentially drug-resistant bacteria. This work provided profound insights into the mechanism of antibiotic degradation by persulfate activating-photocatalysis coupling AOPs.