Heterostructured MWCNTs@PANI@TiO2 Nanocomposites for Enhanced Adsorption of As(III) from Aqueous Solution: Adsorption and Photocatalytic Oxidation Behaviors

Arsenite contamination in groundwater seriously impairs human health due to its high mobility and toxicity. Herein, a novel heterostructured MWCNTs@PANI@TiO 2 nanocomposite was synthesized via a one-pot polymerization process for the adsorption and photocatalytic oxidation of As(III) from aqueous solution. In the dark, the as-synthesized nanocomposite had a high adsorption capacity of As(III) at about 0.29 mmol·g –1 with an initial As(III) concentration of 0.067–0.801 mmol·L –1 at 298.15 K and exhibited a stable adsorption capacity in a wide pH range of 2–9. The adsorption kinetics of As(III) on MWCNTs@PANI@TiO 2 was in accordance with the PSO model and was mainly controlled by chemical adsorption. Under visible light irradiation, the adsorption amount of As(III) on MWCNTs@PANI@TiO 2 was substantially enhanced by about 57%, and the photocatalytic conversion of As(III) to As(V) was found to be caused by the photogenerated holes and superoxide free radical (•O 2 – ). The hypothesized adsorption mechanisms of As(III) and As(V) ions on the nanocomposite were possibly ascribed to surface complexation and hydrogen-bonded interactions. The heterostructured MWCNTs@PANI@TiO 2 nanocomposite offers a promising candidate for highly efficient removal of As(III) ions from arsenite-polluted groundwater.