VISIBLE LIGHT PHOTOCATALYTIC DEGRADATION OF AQUEOUS METHYLENE BLUE BY Ni/Ti LAYERED DOUBLE HYDROXIDE

Abstract

Visible light responsive Ni/Ti layered double hydroxide (LDH) was synthesized by a single step hydrothermal route using commercially available Ni(NO₃)₂.6H₂O, TiCl₄ and urea which exhibited significant UV-visible absorption with a much narrower band gap (2.69 eV) that contributed significantly to the degradation of methylene blue under visible light. X-ray diffraction, Fourier transformed infrared spectroscopy (FT-IR) and N₂ adsorption at 77 K were also carried out to investigate the structure and surface area of the sample. The photocatalytic degradation of aqueous methylene blue (MB) was observed due to the narrow band gap accompanied by comparatively high surface area. The photocatalytic activity improved in alkaline media particularly at pH 11 (catalyst dose 0.075 gL^-1, 1 x 10^-6 M MB). The catalytic activity was found to be higher than commercial catalysts like ZnO, ZnS, TiO₂ and Degussa P25. Thus, this work demonstrated significantly photocatalytic properties of the Ni/Ti LDH in the field of environmental wastewater treatment.