Magnetic MnFe₂O₄/ZIF-67 nanocomposites with high activation of peroxymonosulfate for the degradation of tetracycline hydrochloride in wastewater

Advanced oxidation processes (AOPs) based on PMS have been used to degrade various refractory pollutants such as drugs, endocrine disruptors, dyes and perfluorinated compounds due to their wide application range, mild reaction conditions, fast reaction rate and simple operation. In this study, tetracycline hydrochloride (TCH) was degraded based on this method. Magnetic MnFe2O4/ZIF-67 nanocomposites were successfully prepared by a hydrothermal method, which combined the magnetic separation characteristics of MnFe2O4 with the high catalytic activity of ZIF-67 and were used to activate peroxymonosulfate (PMS) to efficiently degrade TCH. Satisfactory removal results were obtained with this simple and readily available material, with 82.6% of TCH removed in 15 min. The effect of different conditions on the degradation effect was investigated, and the optimal catalyst concentration and PMS concentration were determined to be 0.1 g L-1 and 0.2 g L-1, respectively, and all had good degradation effects at pH 5 to 10. XPS, impedance test and radical quenching experiments were used to investigate the degradation mechanism. The results showed that sulfate radical (SO4-) was the main active species in the degradation process. In addition, the catalyst has good cyclic stability, which provides a new idea for the removal of TCH in wastewater. It is worth mentioning that the catalyst also has good degradation property for other pollutants.