Efficiently photocatalysis activation of peroxymonosulfate by bimetallic metal-organic frameworks Mn-MIL-53(Fe) for ibuprofen degradation: Synergistic efficiency, mechanism and degradation pathways

In this study, a UV-driven photocatalytic activation of peroxymonosulfate (PMS) system was constructed using bimetallic metal-organic frameworks to degrade pharmaceuticals and personal care products (PPCPs). Mn-MIL-53(Fe) was successfully synthesised by adjusting the doping ratio of Mn using solvothermal method. The removal of ibuprofen (IBP) by UV/Mn-MIL-53(Fe)/PMS process was as high as 79.7% in 30 min with a Mn doping ratio of 1.0 (molar ratio of Mn to Fe), and the reaction rate constant was 26.9% higher than undoped. Mn-MIL-53(Fe) had been systematically characterized in terms of its physical structure, microscopic morphology, surface functional groups and photoelectric properties. The mechanism investigation revealed that the cycling of Mn and Fe accelerated the rate of electron transfer in the system, which significantly increased the activation efficacy of PMS to generate more hydroxyl and sulfate radicals for IBP degradation. A total of 13 transformation products were detected during the degradation of IBP by the UV/Mn-MIL-53(Fe)/PMS process. Theoretical calculations were used to predict the sites on the IBP molecule that were vulnerable to attack, and four possible degradation pathways were deduced. The excellent stability and efficient catalytic properties of Mn-MIL-53(Fe) provided a promising solution to the problem of water treatment contaminated with PPCPs.