Metal-organic framework–derived porous Cu–Co bimetallic catalyst for efficient peroxymonosulfate activation toward tetracycline degradation

Abstract

Porous carbon-supported Cu–Co bimetallic catalysts (Cu–Co/NC) were synthesized from a Zn/Co bimetallic metal-organic framework (MOF) precursor and employed for peroxymonosulfate (PMS) activation toward tetracycline (TC) degradation. Among the prepared catalysts, Cu–Co/NC-1 exhibited the highest catalytic activity, achieving approximately 99% TC removal within 6 min with an apparent rate constant of 0.7831 min−1, which was 15.47 times higher than that of the NC/PMS system. Adsorption accounted for only 9.36% of TC removal during the 30 min pre-equilibration period, confirming that rapid TC elimination after PMS addition predominantly originated from catalytic oxidation. The catalyst maintained effective performance over a broad pH range and showed acceptable tolerance toward common coexisting anions. Quenching experiments and EPR analysis indicated that PMS activation proceeded through both radical and nonradical pathways involving SO4·−, ·OH, O2·−, and 1O2. The enhanced catalytic activity is attributed to the cooperative redox behavior of Cu and Co species, together with the contribution of oxygen-containing surface functionalities and the porous N-doped carbon framework. Furthermore, a Cu–Co/NC-1-loaded PTFE membrane reactor maintained high TC removal efficiency during 240 min of continuous operation, demonstrating the feasibility of continuous-flow catalytic degradation. This work provides a rational strategy for developing MOF-derived bimetallic carbon catalysts for PMS-based treatment of antibiotic contaminants.