High efficiency degradation of RhB by MIL-88A(Fe)/MoS2 activated persulfate and its mechanism

MoS₂/MIL-88A (Fe) composite catalyst was prepared by in-situ formation method. The material was characterized by SEM, TEM, XRD and XPS, and the Rhodamine B(RhB) was activated and degraded by persulfate (PMS). The results showed that M-10/M_1:2 had the best degradation effect on RhB, the rate constant was 0.66420 min⁻¹, and the degradation rate could reach 1.89–14 times that of other doped composite catalysts. The SEM results showed that M − 10 had the least sulfur content, fewer MoS₂ flower layers and more exposed Mo⁴⁺ atoms, which improved the electron transfer efficiency and accelerated the degradation reaction. The XPS spectra before and after M-10/M_1:2 reaction showed that the REDOX reaction of Fe³⁺/Fe²⁺ and Mo⁴⁺/Mo⁶⁺ on the catalyst surface played an important role in the activation of PMS. The results of free radical capture experiment and ESR test showed that the main active substances in M-10/M_1:2/PMS reaction system were SO₄^•−, ¹O₂, •O₂⁻, and •OH, which only played a role in the degradation of RhB. Finally, based on the ESR results of M-10/M_1:2/PMS system and the changes of Fe and Mo elements in XPS characterization before and after the reaction, the degradation mechanism of M-10/M_1:2/PMS system was proposed.