Rapid Preparation of TiO_2- and Its Photocatalytic Oxidation for Arsenic Adsorption under Visible Light

A rapid preparation method of TiO_2- by thermal treatment using H₂TiO₃ as the precursor was proposed compared with the static hydrogenation thermal treatment process. Its adsorption properties of arsenic under visible light were explored and investigated as well. Various colors of TiO_2- were prepared and characterized via XRD, TEM, BET, and so on. The results indicate that the method of rapid preparation is feasible. The TiO_2- exhibits a larger particle size that varied from 10 nm to 2 μm, and deeper color products were obtained as the treatment temperature increased from 600 to 900 °C. Light yellow TiO_2- was prepared after increasing the temperature from 600 to 900 °C, Ti₄O₇ and Ti₆O₁₁ with a dark color were formed under a H₂ atmosphere at 1500 °C. The arsenic adsorption performances of some samples under visible light were tested, and reveal a high efficiency of TiO_2- in the photocatalytic oxidation arsenic adsorption under visible light, the conversion ratio of As(III) photocatalytic oxidation fluctuates around 2.85 mgAsg^-1 h^-1. In the absence of visible light, the adsorption capacities for As(III) and As(V) are 3.7 and 42.7 mg/g, respectively, at pH = 3. Under visible light condition, the adsorption capacity of As(III) increases sharply to 15.6 mg/g, which provides the foundation for a new application of TiO_2- in the field of arsenic adsorption.