Photocatalytic degradation of alizarin red dye in aqueous solution using titania-nickel and titania-cobalt nanocomposites

Abstract

Titanium dioxide (TiO₂) was prepared by Sol-gel method which involved hydrolysis of Titanium trichloride (TiCl₃) with concentrated hydrochloric acid and oxidation by hydrogen peroxide. Doping of the TiO₂ was effected at 10% Ni-TiO₂ and 10% Co-TiO₂ using aqueous solutions of nickel nitrate and cobalt nitrate respectively. Characterization by X-ray Diffraction Crystallography (XRD) and Scanning Electron Microscopy (SEM) showed that the surface area and crystallinity of TiO₂ increased through doping. The XRD and SEM data confirmed the observed increase in the photocatalytic activities of the doped versus the undoped TiO₂ photocatalysts. Photocatalytic activities of both the doped and undoped TiO₂ was investigated on the photodegradation of Alizarin red dye. With a constant dye concentration of 25 ppm and temperature of 40 ^oC, it was observed that for all varying concentrations except 0.25 g/l of catalyst at 240 mins, the percentage degradation was of the order TiO₂ < Co-TiO₂ < Ni-TiO₂ . At the 0.25 g/l concentration of catalyst at 240 mins, the photocatalytic activities of the Ni-TiO₂ and Co-TiO₂ were observed respectively to be about 9 times and 12 times that of the TiO₂. 

Keywords: Titanium dioxide, titania-nickel, titania-cobalt,alizarin red and photocatalysts