Improvement of Sulfamethazine photodegradation by Fe(III) assisted MIL-53(Fe)/percarbonate system

Metal-organic frameworks (MOFs) have attracted tremendous interest as photocatalysis for the destruction of organic contaminants. Herein, we synthesize a Fe-based MOF namely MIL-53(Fe), combined with Fe(III) and percarbonate, exhibits photocatalytic activity for the destruction of Sulfamethazine (SMT) under visible LED light irradiation. The morphology and physicochemical properties of the MIL-53(Fe) were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectra (EDS), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). The results indicated that the photocatalytic performance of MIL-53(Fe) with unsatisfactory efficiency resulted from the rapid recombination of photogenerated electrons and holes. This may be suppressed through the introduction of an external electron acceptor (e.g., Fe(III) and percarbonate) to the catalytic process. It could be seen that the SMT degradation efficiency in the system of Vis/MIL-53(Fe)/Fe(III)/SPC attained nearly 90% within 60 min, while only 12% achieved in the system of Vis/MIL-53(Fe). The quenching experiments and EPR analysis were employed to illuminate the predominant reactive species in the system of Vis/MIL-53(Fe)/Fe(III)/SPC. It must be mentioned that the higher separation efficiency of photoinduced electron- hole pairs was achieved via the addition of Fe(III). The accelerated photocatalytic degradation of SMT could be attributed to the subsequent formation of reactive species, which were generated from the activation of SPS by Fe(II) reduced from Fe(III) in the Vis/MIL-53(Fe)/Fe(III)/SPC system. Furthermore, the mineralization of SMT was systematically investigated, as well as the effects of operating parameters (e.g., the dose of catalyst, the concentration of Fe(III), and pH). The work has expanded the possibility of MOFs as visible light responsive photocatalysts together with percarbonate for the remediation of contaminated water.