Enhanced photocatalytic activity of nickel and nitrogen codoped TiO2 under sunlight

Degradation of organic pollutants using modified titanium dioxide (TiO2) has received significant attention in the past years. In this work, nickel (Ni) and nitrogen (N) codoped TiO2 has been used for the effective degradation of phenol. The Ni and N codoped catalyst is synthesized by surface impregnation method and characterized by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of various parameters such as doping, the ratio of dopants in the codoped catalyst, calcination temperature, substrate concentration, catalyst loading and light source on the degradation of phenol is investigated. TiO2 codoped with Ni and N in the ratio 1:0.354 calcined at 400 degrees C was found to be optimum for the degradation of phenol under sunlight. For 25 mg L-1 phenol solution and 1 g L-1 of optimum photocatalyst, a remarkable 95.56% degradation was achieved in 4 h under sunlight. The kinetics of degradation in the concentration range 5-35 mg L-1 was studied, and Langmuir-Hinshelwood (L-H) equation is successfully fitted. The reaction rate constant (k(r)) and equilibrium adsorption constant (K) were determined to be 0.312 mg L-1 min(-1) and 0.035 L mg(-1), respectively. The results of the study show that Ni and N codoped TiO2 is a promising photocatalyst for the degradation of phenol under sunlight. (C) 2020 Elsevier B.V. All rights reserved.