Efficient peroxydisulfate activation by a CoNiFc-MOF for rapid removal of emerging contaminants via both radical and non-radical pathways

Abstract

In the study presented in this paper, a multimetallic ferrocene-based metal–organic framework (CoNiFc-MOF) catalyst, characterized by a sea urchin-like morphology, was synthesized via a straightforward solvothermal method. The research focused on evaluating the efficacy of peroxydisulfate (PDS) activation by the CoNiFc-MOF catalyst for the removal of emerging contaminants. The results indicated that the CoNiFc-MOF catalyst achieved a removal efficiency exceeding 98% for 10 mg L⁻¹ bisphenol A (BPA) within a 5 min timeframe. The activation mechanism of PDS was elucidated through electron paramagnetic resonance (EPR), revealing the involvement of both radical and non-radical oxidation pathways. In this non-radical mechanism, BPA undergoes oxidation via a direct electron transfer pathway facilitated by the metastable reaction complex (CoNiFc-MOF/PDS*). The leaching percentages of Co, Ni, and Fe were calculated to be 3.9%, 3.8%, and 7.5%, respectively, based on ICP-MS analysis of the reaction solution before and after catalysis. The CoNiFc-MOF catalyst demonstrated a high removal efficiency, consistently maintaining over 90% efficiency across five consecutive cycles, indicative of its remarkable catalytic activity and stability. The intermediates of BPA were further identified using liquid chromatography-mass spectrometry (LC-MS), leading to the proposal of four potential degradation pathways. The catalyst also proved high efficacy in the removal of bisphenol B (BPB), tetracycline (TC), and oxytetracycline (OTC), with the reaction rate being closely associated with its structural characteristics and properties. Moreover, the CoNiFc-MOF catalyst is notable for its straightforward synthesis process and low cost, offering a promising design strategy for the development of efficient PDS-activated catalytic materials.