Enhanced degradation of organic water pollutants by photocatalytic in-situ activation of sulfate based on Z-scheme g-C3N4/BiPO4

In recent years, the excellent performance of sulfate radical (SO4 center dot-) in advanced oxidation process has attracted more and more attention. However, it requires the consumption of expensive persulphate (PMS/PDS), and the resulting sulfate ion (SO42-) requires subsequent processing procedures, which limits its practical application value. In this work, a Z-scheme heterojunction g-C3N4/BiPO4 (CNBx) photocatalyst was constructed to in-situ activate the residual SO42-, H2O and dissolved O-2 in organic wastewater simultaneously and produce SO4 center dot-, center dot OH and O-2(center dot)- efficiently, so as to realize enhanced organic pollutant treatment by using clean and renewable solar energy resources. Under the condition of 10 mM SO(4)(2-)addition and 100 mW center dot cm(-1) illumination, the degradation rate of BPA (C0 = 20 mg center dot L-1) by optimized CNB150 catalyst was 0.30 min(-1), which was 50% higher than that without SO42-(0.20 min(-1)). Detailed characterizations shown that a direct Z-scheme heterojunction was formed between g-C3N4 and BiPO4, which could be simultaneously stimulated by light, and then effective charge separation and migration could be achieved through the internal electric field caused by the Fermi-level difference between the g-C3N4 (-0.12 eV) and BiPO4 (0.01 eV). In general, this study makes full use of renewable solar energy and provides a feasible path for promoting the simultaneous in-situ utilization of small molecules (SO42-, H2O and O-2) that originally exist in water, which makes organic wastewater treatment more economic, eco-friendly and sustainable.

Automated summary

This study constructed a Z-scheme heterojunction g-C3N4/BiPO4 photocatalyst, which can simultaneously activate and utilize SO42-, H2O and O2 in organic wastewater, achieving efficient treatment of organic pollutants.