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