Recent progress in photocatalysts for oxidation of As(III) and photocatalyst-impregnated adsorbents for removing aqueous arsenic

Arsenic (As) in drinking water remains a major challenge to public health globally. Since aqueous As is often present as As(III), oxidation of As(III) to As(V) by photocatalysis is an efficient and low-cost treatment method for As removal from water, as As(V) is readily removed by adsorption. Novel photocatalysts such as C/TiO₂@Fe₃O₄, WO₃/TiO₂, Fe/TiO_2, Bi_2.15WO₆, and g-C₃N₄ can efficiently (100% or close) oxidize As(III) in 6–150 min under UV irradiation, and in 12–180 min under visual light irradiation. Furthermore, impregnating nanoscale photocatalysts into adsorbents such as metal oxides (e.g., Fe₂O₃, Fe₃O₄), activated carbon, and chitosan enables both As(III) oxidation and adsorption of the resulting As(V) in up to 90 min by using these integrated materials, which can be separated from water by sedimentation or magnetism. These novel technologies provide economically feasible and environmentally friendly options for As abatement, particularly in decentralized water systems in developing communities.