Oxalate enhanced synergistic removal of chromium(VI) and arsenic(III) over ZnFe2O4/g-C3N4: Z-scheme charge transfer pathway and photo-Fenton like reaction

In this work, direct Z-Scheme photocatalyst (ZnFe 2 O 4 /g-C 3 N 4 ) was employed to purify Cr(VI) and As(III) in wastewater. Results showed that Cr(VI) and As(III) was completely removed in a wide pH range of 3–7 under visible light irradiation. During photo reaction, oxalate enhanced the generation of Fe(II) and CO 2 − , which were beneficial for formation of OH and O 2 − . In photocatalytic system, Fe(II), photogenerated electron, as well as CO 2 − contributed to Cr(VI) reduction, OH and O 2 − were responsible for treatment of As(III). Moreover, ZnFe 2 O 4 /g-C 3 N 4 was easily recycled by magnetic separation, and presented an excellent reuse ability in treatment of Cr(VI) and As(III).