Activation of persulfate with magnetic Fe3O4-municipal solid waste incineration bottom ash-derived zeolite core-shell materials for tetracycline hydrochloride degradation

A novel and environmentally friendly magnetic iron zeolite (MIZ) core-shell were successfully fabricated using municipal solid waste incineration bottom ash-derived zeolite (MWZ) coated with Fe₃O₄ and innovatively investigated as a heterogeneous persulfate (PS) catalyst. The morphology and structure composition of as-prepared catalysts were characterized, and it was proved that the core-shell structure of MIZ was successfully synthesized by coating Fe₃O₄ uniformly on the MWZ surface. The tetracycline hydrochloride (TCH) degradation experiment indicate that the optimum equimolar amount of iron precursors was 3 mmol (MIZ-3). Compared with other systems, MIZ-3 possessed a superior catalytic performance, and the degradation efficiency of TCH (50 mg·L^-1) in the MIZ-3/PS system reached 87.3%. The effects of reaction parameters on the catalytic activity of MIZ-3, including pH, initial concentration of TCH, temperature, the dosage of catalyst, and Na₂S₂O₈, were assessed. The catalyst had high stability according to three recycling experiments and the leaching test of iron ions. Furthermore, the working mechanism of the MIZ-3/PS system to TCH was discussed. The electron spin resonance (ESR) results demonstrated that the reactive radicals generated in the MIZ-3/PS system were sulfate radical (SO₄^-•) and hydroxyl radical (•OH). This work provided a novel strategy for TCH degradation under PS with a broad perspective on the fabrication of non-toxic and low-cost catalysts in practical wastewater treatment.