Z-scheme TiO2 derived from MIL-125(Ti)/g-C3N5 heterojunction for enhanced photocatalytic degradation of sulfadiazine via peroxymonosulfate activation

A catalyst, Ti-MIL@g-C3N5, was successfully synthesized by combining g-C3N5 nanosheets with carbonized MIL125(Ti) for peroxymonosulfate (PMS) activation under visible light irradiation for sulfadiazine (SDZ) removal from wastewater. The result demonstrated that with the narrow bandgap, the composite Ti-MIL@g-C3N5 catalyst exhibited the superior SDZ removal performance. Efficient degradation of 0.04 mM SDZ in a 50 mL solution was accomplished in just 15 min using 100 mg L-1 of Ti-MIL@g-C3N5 catalyst, and 0.4 mM of PMS. The quenching test and electron paramagnetic resonance (EPR) results disclosed the reactive species (1O2, SOS ,and O 2 ) were mainly attributed to accelerating the PMS activation and SDZ degradation. The catalyst remained the high performance for SDZ removal after five consecutive cycles. Moreover, the Ti-MIL@g-C3N5/PMS/visible light (TiMIL@g-C3N5/PMS/vis) system demonstrated high and stable SDZ removal performance in real water samples and with various pharmaceutical compounds. This work proved the great potential of composite catalyst in advanced oxidation process for contaminant elimination and environmental pollution control.