Application of Ag-doped TiO2nanoparticle prepared by photodeposition method for nitrate photocatalytic removal from aqueous solutions

Abstract

Nitrate pollution in surface and groundwater resources is considered as an environmental challenge because of the potential risks of nitrate in diseases such as methemoglobinemia, lymphatic disturbances, and blood cancer. On the other hand, nanomaterials have been recently applied for the control of water pollutants. The objective of this research was to investigate the efficiency of silver-doped TiO2 nanoparticles prepared by photodeposition method under UV irradiation for nitrate removal. Ag-doped TiO2 nanomaterials (Ag/Ti = 0.1 at %) were characterized by scanning electron microscope-energy dispersive X ray, transmission electron microscope, X-ray diffraction, and BET and used in doses of 0.1, 0.4, 0.8, and 1.2 g/L. Three nitrate concentrations of 20, 50, and 100 mg/l were considered in the pH range of 5–9. The effect of Ag-doped TiO2 nanoparticles both in dark and with UV irradiation was studied. Nitrite and ammonia, as intermediates of photocatalytic degradation of nitrate, were detected by spectrophotometric method. Also, in the study, the effect of change in Ag percent doped on TiO2 under UV irradiation for nitrate removal was investigated. The effect of calcination temperature was surveyed on Ag-doped TiO2/UV process efficiency in nitrate removal from aqueous solutions. The optimum performance of nitrate removal (95.5%) was obtained with initial concentration of 100 mg/l and in acidic pH. Increase of Nanoparticle concentration up to 0.8 g/L, improved the removal efficiency, but 1.2 g/l of nanoparticles reduced the degradation efficiency. Maximum reduction performances without nanoparticles (with UV irradiation and in dark) were 32 and 23.3%, respectively. Optimal calcination temperature and optimal silver content doped on TiO2 was obtained at 400°C and 1%.