A heterogeneously activated peroxymonosulfate with a Co and Cu codoped bimetallic metal-organic framework efficiently degrades tetracycline in water

In the study presented in this paper, a cobalt and copper codoped bimetallic metal-organic framework (CoCu–MOF) was synthesized by a solvothermal method. The CoCu–MOF was then utilized to activate peroxymonosulfate (PMS) to degrade the tetracycline (TC) present in water. When the concentration of organic pollutants was 20 mg/L, the degradation efficiency of TC by the Co1Cu1–MOF/PMS system reached 98.17 % within 30 min, which was better than that of the PMS and Cu-MOF/PMS systems alone. The effects of catalyst addition, PMS usage, initial pH, temperature, coexisting ions and initial TC concentration on the degradation of TC by Co1Cu1–MOF were investigated. The sulfate radical (SO4•−), hydroxyl radical (•OH), superoxide radical (O2•−), and nonradical singlet oxygen (1O2) were identified as the primary reactive species through quenching experiments and electron paramagnetic resonance (EPR) analyses. Moreover, linear sweep voltammetry (LSV) analysis was used to determine the occurrence of an electron transfer-mediated nonradical pathway in the reaction system in addition to 1O2. The concentrations of the TC intermediates were determined using liquid chromatography‒mass spectrometry (LC‒MS), and potential degradation processes were proposed. This study showed that CoCu–MOF is a heterogeneous catalyst that activates PMS for efficient TC degradation.