Zif-67-Derived Nico-Mof for Catalytic Activation of Peroxymonosulfate To Degrade Norfloxacin:Mechanism, Degradation Pathway, and Toxicity Analysis

Abstract

In this study, a hollow-structured bimetallic metal-organic framework (NiCo-MOF, NCM) was synthesized through a direct etching method using a zeolitic imidazolate framework (ZIF) as the precursor. The NCM catalyst exhibited excellent performance in activating peroxymonosulfate (PMS) for the degradation of norfloxacin (NOR), achieving nearly complete removal within 60 minutes.Comprehensive structural characterization and batch experiments demonstrated that the remarkable catalytic efficiency of NCM/PMS was attributed to its petal-like surface morphology, which provided abundant reactive sites for PMS activation, as well as the synergistic interaction between the Ni and Co active centers. NOR consistently maintained a good degradation rate under the influence of catalyst dosage, PMS amount, pollutant concentration, pH, inorganic anions, and HA.Even after modifications in the catalyst’s chemical composition during the reaction, the NCM retained satisfactory stability, maintaining a NOR degradation efficiency of 70% after five consecutive cycles.Mechanistic investigations, including electron paramagnetic resonance (EPR) analysis, quenching experiments, and electrochemical characterization, revealed that the NOR degradation involved a hybrid mechanism of radical oxidation (SO4·-) and non-radical oxidation (1O2) facilitated by electron transfer processes. Density functional theory (DFT) calculations identified the most vulnerable reactive sites on the NOR molecule, while intermediate products were analyzed to propose a plausible degradation pathway. Furthermore, toxicity assessments demonstrated a significant reduction in the ecological toxicity of NOR after degradation.This work provides a robust in-situ grown bimetallic MOF catalyst for peroxymonosulfate-based advanced oxidation processes, offering a promising strategy for the removal of antibiotics and environmental remediation.

Keywords: Peroxymonosulfate、NiCo-MOF、norfloxacin、Degradation mechanism、DFT caculation