N-doping modified zeolitic imidazole Framework-67 (ZIF-67) for enhanced peroxymonosulfate activation to remove ciprofloxacin from aqueous solution

Abstract

In this study, N doped ZIF-67 (N@ZIF-67) was prepared via hydrothermal method and applied for heterogeneous catalytic activation of peroxymonosulfate (PMS) in the remediation of pharmaceuticals, exemplified by antibiotic ciprofloxacin (CIP) in aqueous solution. The morphological and physicochemical properties of N@ZIF-67 were characterized and the catalytic activity for degradation of organic contaminants was studied. The N@ZIF-67 significantly enhanced electron transfer between reacting species with excellent catalytic performance in CIP degradation. CIP degradation in the N@ZIF-67/PMS system took place over a broad pH range of 5 to 9. Moreover, the synergistic effect between nitrogen and ZIF-67 structure not only significantly boosted the CIP removal efficiency but also long-term stability of the composite. The dissolution of cobalt ion was below the allowable drinking water standard. The superoxide radical (O2⋅−) was not only involved in the generation of singlet oxygen (1O2) but also played a crucial role in CIP degradation. This proof-of-concept study for the development of N@ZIF-67 paves the new venue for wastewater remediation through PMS activation.