Biological renewable hemicellulose-template for synthesis of visible light responsive sulfur-doped TiO2 for photocatalytic oxidation of toxic organic and As(III) pollutants

Abstract

Sulfur-doped TiO2 catalysts using biological renewable hemicellulose template (S/TiO2-T) were synthesized and characterized with different instruments. The photocatalytic activities of the resulting S/TiO2-T photocatalysts with different amounts of S-doped TiO2 were investigated through the decomposition of toxic nitrobenzene, p-chlorophenol, and phenol organic compounds and oxidation of As(III) pollutant under visible light irradiation. The highest photocatalytic activity was obtained from S/TiO2-T catalyst prepared with the n(TiCl4)/n(Thiourea) precursor molar ratio of 4/2 after calcinations at 600 °C to achieve the complete removal of nitrobenzene within 40 min. However, only 75.2%, 8.8%, and 7.9% were removed by S/TiO2, TiO2-T, and P25-TiO2, respectively. It was also observed that the S/TiO2-T(4/2) catalyst had higher catalytic efficiency for oxidation of As(III) under visible light irradiation. The complete oxidation of 250 ml (50 mg/L) of As(III) solution was achieved within 20 min under visible light irradiation by 125 mg S/TiO2-T(4/2) catalyst. The hemicellulose aided synthesis led to high dispersion, small grain size, and high specific surface area of S/TiO2-T catalysts. Moreover, the S-doping of TiO2 is also the key factor for the visible light responsive degradation of toxic organic compounds and oxidation of As(III), and using the template in the synthesis further improves the catalytic performances.