Photocatalytic treatment of landfill leachate: A comparison between N-, P-, and N-P-type TiO2 nanoparticles

Abstract

Abstract Landfill leachate is included in the group of recalcitrant wastewaters and its treatment is a necessary measure for environmental protection and sustainable development. Photocatalytic treatment method using N-, P-, and N-P-type TiO2 nanoparticles under visible light irradiation has been recently considered for the treatment of recalcitrant wastewaters. Since the oxidizing agents in each type of nanoparticles are different, their efficiency for pollutant treatment is different. Therefore, this study aims at comparing the leachate treatment efficiency using N-, P-, and N-P-type TiO2 under visible light irradiation. For this purpose, TiO2 nanoparticles were doped by tungsten (W) and carbon (C) separately and simultaneously (W-C). The effect of leachate pH, dopant content, calcination temperature, and exposure time on the leachate treatment efficiency was experimentally investigated and optimized. Finally, the best nanoparticle type for leachate photocatalytic treatment was determined by performing experiments with same leachate under the optimum conditions of each type of nanoparticles. Based on the results, the COD removal efficiency for leachate with 2,050 mg/L initial COD in the photocatalytic treatment process using W-doped, C-doped, and W-C-codoped TiO2 nanoparticles was 46, 60, and 64%, respectively, after 46 h exposure time. The findings of this study provide researchers with new insights about the most efficient doped TiO2 nanoparticles for leachate treatment under visible light irradiation using slurry and fixed bed reactors.