Dual coordination between loess and N-doped TiO2 for efficient removal and degradation of organics

Organic dyes pollution (especially methylene blue) in wastewater has seriously affected the livelihood and health of human beings. To address this issue, in this study, loess-based N-doped TiO 2 (NTiO 2 @ALS) photocatalysts were fabricated through in situ deposition of N-doped TiO 2 (NTiO 2 ) nanoparticles on the surface of acidified loess (ALS) particles by sol-gel method. The characterization was performed by XRF, SEM, FT-IR, XRD, XPS, UV–Vis DRS and BET, and small nanoparticles of NTiO 2 were found to be perfectly bound to the surface of the ALS particles. In addition, what factors affecting the photocatalytic activity were explored and it was found that calcination at 450 °C for 2 h was the best condition, under which the samples possessed the highest degradation efficiency under visible light irradiation. Furthermore, NTiO 2 @ALS was applied to the degradation of methylene blue (MB) and the mechanism of pre-adsorption and photocatalytic degradation was also investigated. Surprisingly, methylene blue (MB) could be degraded by 99.6% post pre-adsorption. This excellent result was attributed to the existence of dual coordination between catalytic active center (NTiO 2 ) and support (ALS) in NTiO 2 @ALS. Most significantly, the introduced ALS particles achieved the effective dispersion of small NTiO 2 nanoparticles and increased the specific surface area of materials, which greatly improved photocatalytic performance and adsorption properties. In brief, NTiO 2 @ALS holds promising application potential for the removal and degradation of organic dyes from wastewater.