Synergistic degradation of oxytetracycline hydrochloride by persulfate activated by Ni-doped MIL-88A three-dimensional catalyst: Free radical and non-free radical pathways

The advanced oxidation technology of persulfate has great potential in removing pollutants. Appropriate bimetallic activation method has obvious synergistic effect on the formation of free radicals and non-free radicals, and can also promote the electron transfer process. Therefore, in this paper, Ni was doped on the iron-based metal organic framework (MIL-88A) to form bimetallic catalyst and used as persulfate activator for oxytetracycline (OTC) degradation. The introduction of Ni increased the specific surface area of the catalyst and significantly improved its catalytic performance. Within 30 min, the degradation efficiency of 5 mg/L OTC reached 81.30%. The used catalyst can be simply recovered by standing, and the catalytic stability is high. The composition of main reactive oxygen species (ROS) in pollutant decomposition was clarified through the analysis of degradation mechanism. In addition to typical •OH、SO4•− and O2•−, non-free radical 1O2 was also generated. Based on LC-MS detection and toxicological experiments, the possible degradation pathways were proposed and the toxicity was analyzed. This material provides a new insight for activating PS to remove refractory organic compounds, and promotes the application of Fe-MOF materials in environmental pollution remediation.