A magnetic γ-Fe2O3@PANI@TiO2 core–shell nanocomposite for arsenic removal via a coupled visible-light-induced photocatalytic oxidation–adsorption process

Abstract

Arsenic polluted groundwater impairs human health and poses severe threats to drinking water supplies and ecosystems. Hence, an efficient method of simultaneous oxidation of As(III) to As(V), and removal of As(V) from water has triggered increasing attention. In this study, a magnetic γ-Fe₂O₃ core–shell heterojunction nanocomposite was synthesized by means of hydrothermal crystallization of TiO₂ on the surface of the magnetic core–shell loaded with polyaniline (γ-Fe₂O₃@PANI@TiO₂). As an efficient photocatalyst coupled with adsorption, γ-Fe₂O₃@PANI@TiO₂ has a high light utilization and good adsorption capacity. Notably, the nanocomposite has excellent stability at various initial pH values with good reusability. Among the co-existing ions investigated, PO₄³⁻ has the greatest competitive reaction. The photocatalytic oxidation of As(III) on γ-Fe₂O₃@PANI@TiO₂ is dominated by the synergy of several active substances, with superoxide free radicals and photogenerated holes being the major players.