Visible-light activation of persulfate by TiO2/g-C3N4 photocatalyst toward efficient degradation of micropollutants

[Display omitted] •A novel TiO2/g-C3N4-PS system was proposed for micropollutant degradation.•The TiO2/g-C3N4-PS system exhibits a high efficiency, nonselectivity and great stability.•The effects of different reaction conditions on the degradation rate of AAP were systematically studied.•The addition of PS greatly improved the degradation efficiency and oxidizing performance of the TiO2/g-C3N4 system.•The photocatalytic mechanism in the TiO2/g-C3N4-PS system was proposed. A novel TiO2/g-C3N4-PS system was proposed, in which a TiO2/g-C3N4 heterojunction was used to activate persulfate (PS) to enhance pollutant photodegradation under visible-light irradiation. In this study, the TiO2/g-C3N4 photocatalyst was synthesized by a simple calcination method, and acetaminophen (AAP) was chosen as a model pollutant to test the degradation efficiency of the photocatalytic system. The TiO2/g-C3N4-PS system exhibits an efficient activity for PS activation and a high efficiency for pollutant degradation. The results show that 100 mL of a 5 mg/L AAP solution could be almost completely degraded in 30 min with 0.5 g/L photocatalyst and 2 mM PS, and TOC can be decreased by 82.5% in 60 min. After adding PS, the degradation rate of the TiO2/g-C3N4 photocatalytic system was greatly improved by nearly 13 times, compared to the TiO2/g-C3N4 system. The radical quenching experiments and electron paramagnetic resonance (EPR) results indicate that SO4−, OH and h+ all contribute to eliminating organic compounds. Additionally, the TiO2/g-C3N4-PS photocatalytic system was employed to eliminate other typical micropollutants, such as phenol, bisphenol A and carbamazepine, and experiments were also carried out using real water matrices, and the ideal performance shows that the TiO2/g-C3N4-PS photocatalytic system has a strong nonselective oxidative ability for degrading contaminants.