Enhanced photocatalytic oxidation of Sn/N co-doping TiO2 on As(III) under visible light

Abstract

The photocatalytic oxidation technology has been verified as an effective method to oxidize As(III) to As(V) with low toxicity and the photocatalyst with perfect performances is still the core factor in the treatment procedure. In this paper, a high property photocatalyst of Sn/N co-doping TiO2 (Sn/N-TiO2) has been synthesized and applied to the photocatalytic oxidation of As(III). Through a series of characterization methods, it is proved that Sn and N atoms have been effectively doped into the crystal structure of TiO2, which makes the optical absorption wavelength of TiO2 extend from ultraviolet light to visible light region. At the same time, the presence of O-Ti-N bonds can offer an efficient electron moving path and further improve the photogenerated electron transfer rate, so as to enhance the photocatalytic oxidation effect. The synthesized Sn/N-TiO2 photocatalyst only takes 21 min to realize complete oxidation of As(III) (10,000 μg/L, 40 mL) to As(V) under visible light, superior to N-doped TiO2 (27 min) and Sn doped TiO2 (24 min) photocatalysts. The achievements of such efficient photocatalytic oxidation performances result from the synergistic interaction of hydroxyl radicals (·OH), superoxide radical (·O2–), and hole (h+) formed in the photocatalytic oxidation process and the O-Ti-N bond formed by co-doping. This paper provides a new insight for solving arsenic pollution by photocatalytic oxidation technology.