Arsenite removal from aqueous solutions by γ-Fe2O3–TiO2 magnetic nanoparticles through simultaneous photocatalytic oxidation and adsorption

Abstract

A novel Fe–Ti binary oxide magnetic nanoparticles which combined the photocatalytic oxidation property of TiO2 and the high adsorption capacity and magnetic property of γ-Fe2O3 have been synthesized using a coprecipitation and simultaneous oxidation method. The as-prepared samples were characterized by powder XRD, TEM, TG-DTA, VSM and BET methods. Photocatalytic oxidation of arsenite, the effect of solution pH values and initial As(III) concentration on arsenite removal were investigated in laboratory experiments. Batch experimental results showed that under UV light, As(III) can be efficiently oxidized to As(V) by dissolved O2 in γ-Fe2O3–TiO2 nanoparticle suspensions at various pH values. At the same time, As(V) was effectively removed by adsorption onto the surface of nanoparticles. The maximum removal capability of the nano-material for arsenite was 33.03mg/g at pH 7.0. Among all the common coexisting ions investigated, phosphate was the greatest competitor with arsenic for adsorptive sites on the nano-material. Regeneration studies verified that the γ-Fe2O3–TiO2 nanoparticles, which underwent five successive adsorption–desorption processes, still retained comparable catalysis and adsorption performance, indicating the excellent stability of the nanoparticles. The excellent photocatalytic oxidation performance and high uptake capability of the magnetic nano-material make it potentially attractive material for the removal of As(III) from water.