Simulated Solar Light Driven Fe(III)/Fe(II) Redox Cycle for Roxarsone Degradation and Simultaneous Arsenate Immobilization

•A solar light driven Fe(III)/Fe(II) cycle strategy was used to treat roxarsone.•Partial hydrolysis of Fe(III) could degrade 85.3 % of roxarsone into arsenate.•Complete hydrolysis of Fe(III) could immobilize the generated arsenate.•The residual arsenate concentration in the solution was as low as 58 μg L−1.•DFT calculation was used to analyze the photo-reactivity of the Fe(III) species.