Photocatalytic treatment of 2,4,6-trinitotoluene in red water by multi-doped TiO2 with enhanced visible light photocatalytic activity

Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 were prepared with Fe doping peroxotitanium complex (Fe-PTC) as precursor in aqueous solution by a low-temperature process. The structure and properties of catalysts were characterized by XRD, FT-IR, XPS, TEM and UV–Vis respectively. Fe-N-doped TiO2, Fe-S-doped TiO2 and Fe-N-S-doped TiO2 all belong to anatase phase. The UV–Vis spectra of doped TiO2 exhibited a red shift to 535 nm and stronger absorption than that of pure TiO2 in visible region. The pure TiO2 displays bullet-like morphology with widths of about 20 nm and Fe-N-S-doped TiO2 consisted of irregular particles with diameters about 5–10 nm. The doped samples all exhibited higher photocatalytic activity in the degradation of 2,4,6-trinitotoluene (TNT) in red water compared to pure TiO2. Fe-N-S-doped TiO2 presented the highest photocatalytic activity and degraded about 91.5% 2,4,6-trinitotoluene within 12 h under visible light irradiation. Structural characterization and property analysis results revealed that the co-doping of Fe-N, Fe-S and Fe-N-S remarkably altered the crystal specific surface area, microstructure, as well as the photocatalytic activity.