Efficient and stable activation of persulfate to degrade antibiotics by double redox MOF: Performance and mechanism

Abstract

Aim at that problem of Fe(II) regeneration of iron-based catalyst in persulfate system, an efficient bimetallic organic skeleton catalyst (2D-MOF NSs@88A-Cu) was designed and synthesized to promote the regeneration of Fe(II) through the redox cycle of Cu, thus improving the activation efficiency of PDS. In the 2D-MOF NSs@88A-Cu/PDS system, the transformation from Cu(I) to Cu(II) effectively drives the reduction of Fe(III) to Fe(II), which significantly improves the ability of the catalyst to remove oxytetracycline (OTC). Through electrochemical test, quenching experiment and electron paramagnetic resonance (EPR) analysis, the synergistic mechanism of adsorption-catalytic oxidation of the catalyst was revealed. Specifically, 2D-MOF NSs@88A-Cu, with its unique structural characteristics, significantly enhanced the adsorption capacity of OTC through electrostatic attraction and π-π stacking, and the adsorption process was mainly physical adsorption and multi-layer adsorption. At the same time, the efficient electron transfer ability of the catalyst and the production of rich reactive oxygen species (SO₄^•−, •OH, O₂^•−, and ¹O₂) and Fe(IV) promote the efficient catalytic oxidative degradation of OTC. In addition, the catalytic durability and recovery performance of 2D-MOF NSs@88A-Cu were evaluated by a self-built continuous flow reactor system. The results showed that the catalyst had good stability and recovery. In a word, the 2D-MOF NSs@88A-Cu catalyst developed in this study provides an effective solution to the problem of antibiotic wastewater. Moreover, it also provides a new perspective and reference for the application of advanced oxidation technology in environmental remediation.