Targeted degradation of sulfamethoxazole in wastewater by molecularly imprinted MOFs in advanced oxidation processes: Degradation pathways and mechanism

It seems to be a feasible strategy to treat organic micro-pollutions in wastewater by enriching pollutants toward the surface of catalyst before its degradation. In this study, NH2-MIL-53(Fe) (metal organic frameworks) surface molecularly imprinted catalyst (MIP-AA) was synthesized for investigating the targeted degradation mechanism of Sulfamethoxazole (SMX) in advanced oxidation processes (AOPs). The catalyst exhibited the accurate recognition and catalysis property for SMX, and the removal rate of SMX reached 38.04 mg/g collaborated with the adsorption and catalysis of MIP-AA. The degradation mechanism was studied according to the degradation pathways and the results of density functional theory (DFT), which was applied to predict the reaction active sites of SMX. UV–vis analysis and kinetic confirmed that pre-adsorption of MIP-AA mainly concentrated pollutants toward the catalyst through weak interactions such as hydrogen bonds. Besides, the weak interactions would also enrich the intermediate products in the surface of the catalyst to promote its degradation but without affecting the active sites of SMX. Moreover, radical quenching experiments showed that ·OH was the predominant free radical and the imprinted layer in MIP-AA was not affected its generation. These results indicated that the imprinted layer only provided the recognition sites and specific pore structures but not involved the process of catalysis. These characteristics ultimately led to the reduction of types of intermediate products and degradation pathways of SMX in the MIP-AA catalysis system.