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

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[rad]⁻, [rad]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.