One-Pot Synthesis of a Magnetic TiO<sub>2</sub>/PTh/γ-Fe<sub>2</sub>O<sub>3</sub> Heterojunction Nanocomposite for Removing Trace Arsenite via Simultaneous Photocatalytic Oxidation and Adsorption
Xuemei Liu, Yuan Wang, Tian C. Zhang, Gang Xiang, Xin-Long Wang, Shaojun Yuan
Abstract
Arsenic pollution has drawn wide attention, owing to its severe carcinogenicity, strong poisonousness, and high mobility in groundwater. Herein, a magnetic heterojunction nanocomposite of TiO2/polythiophene/γ-Fe2O3 (TiO2/PTh/γ-Fe2O3) was fabricated by one-pot oxidation polymerization as a novel photocatalyst for removing trace As(III) from aqueous solution by a visible-light-driven photocatalytic oxidation–adsorption coupling process. The nanocomposite showed excellent stability to adsorb As(III) in a low-pH region (2–6). Under dark conditions, approximately 46.5% of As(III) was adsorbed by the as-synthesized nanocomposite, and the kinetic data indicated the dominating chemical adsorption. However, under visible light illumination, more than 99.1% of As(III) was transformed into As(V) and simultaneously 90.1% of produced As(V) was adsorbed by the nanocomposite. Furthermore, the photogenerated holes (h+) and superoxide free radicals (•O2–) were the main reactive substances on the TiO2/PTh/γ-Fe2O3 nanoparticle for visible-light-driven photocatalytic oxidation of As(III). The novel magnetic TiO2/PTh/γ-Fe2O3 heterojunction nanocomposite may have potential application for arsenic removal in the aquatic environment.