Effective photocatalytic removal of As(III) by ZnFe2O4/Ag/AgCl coupled peroxymonosulfate: Z-Scheme charge transfer and dual active sites

Inorganic arsenic threatens human health due to its high mobility and toxicity. In this work, rapid and effective treatment of As(III) wastewater was achieved by Z-Scheme photocatalyst (ZnFe 2 O 4 /Ag/AgCl). By means of peroxymonosulfate (PMS) activation, 50 mg/L As(III) was completely removed within 20 min under light irradiation. During photocatalytic system, free radicals ( SO 4 − , OH, O 2 − ) and non-radicals ( 1 O 2 ) were responsible for As(III) removal. The fast PMS activation was attributed to the loop conversion of Fe(III)/Fe(II) and Ag 0 /Ag + . Besides, density functional theory (DFT) calculations exhibited that Fe atoms were active sites for As(III) adsorption and Ag nanoparticles were spots for PMS activation. Specially, the dual active sites on photocatalyst could effectively minimize the distance between oxidizing product with arsenite molecular and thus facilitate As(III) fast oxidation.