Photoreduction of Cr(VI) Catalyzed by TiO2-Lignin

Abstract

In order to increase  the  activity of TiO₂ photocatalyst, preparation and characterization of TiO₂-lignin and its activity on Cr(VI) photoreduction have been carried out. TiO₂-lignin was prepared by mixing TiO₂ powder with lignin powder  in water-ethanol followed by stirring for 24 h and calcination at 400°C. The crystal structure characterizations were performed by X-ray diffraction (XRD), Lignin was identified using FT-IR whereas photoreduction of Cr(VI) was conducted in a batch reactor. The effect of TiO₂ content on TiO₂-lignin, irradiation time, weight of photocatalyst and initial concentration of Cr(VI) were studied to obtain effectiveness of photoreduction. Activity of TiO₂-lignin on the photoreduction of Cr(VI) showed higher result than TiO₂. The increased of TiO₂ content in TiO₂-lignin result in higher Cr(VI) photoreduction and gave maximum yield at mass ratio of TiO₂/lignin 2:1. The irradiation time, weight of TiO₂-lignin photocatalyst and initial concentration of Cr(VI) obtained for maximum Cr(VI) photoreduction are 40 h, 50 mg and 1 mg/L respectively which reduced Cr(VI) by 81.44%. 

Keywords: TiO₂-lignin, Cr(VI) ion, photoreduction