Photocatalytic degradation of dyestuff wastewater with Zn(2+)-TiO2-SiO2 nanocomposite.

A novel photocatalyst of Zn(2+)-TiO2-SiO2 nanocomposite has been prepared by a sol-gel method, which is used for the degradation of Rhodamine B (RhB) and Congo red (CR) as the probe dyestuff that are notorious organic compounds present in dyes wastewater. The prepared samples are characterized by low temperature N2 adsorption (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (DRS) and Fourier transformed infrared spectroscopy (FT-IR). It is found that the nanocomposite of Zn(2+)-TiO2-SiO2 exhibits much higher photocatalytic activity under both UV light and visible light irradiation as compared with Degussa P25, Zn(2+)-TiO2 and SiO2-TiO2. The photodegradation efficiencies of RhB (5 mg/L) and CR (10 mg/L) can reach above 90% and 83% for 1.5 h visible light irradiation, respectively. Synergetic effect between Zn(2+)-SiO2-doping not only inhibit the crystal growth and anatase-to-rutile transformation of TiO2 nanocatalyst, but also extend the light response to the visible region, which provides a good way and material in the degradation field of dyes wastewater.