Enhanced photocatalytic activities of metal doped titania catalysts in the degradation of some textile reactive azo dyes

Abstract

Our environment has been under serious threat from various newlinecontaminants and one of the major sources of contaminations is dyestuff newlinewhich comes from textile industries Several chemical physical and newlinebiological processes such as flocculation ultra filtration adsorption newlineozonation and chlorination for treating the textile industrial effluents are newlineineffective because they ultimately cause secondary pollution which requires newlinefurther treatment newlineTitanium dioxide is known to be an excellent semiconductor newlinephotocatalyst for various environmental protection applications Even though newlineit is an excellent catalyst its wide band gap 32 V limits its usage in visible newlinelight The normal 35 share of UV light in typical sunlight is not sufficient newlineto activate titania catalyst Therefore improving its efficiency has become an newlineimportant challenge for researchers around the world newlineNumerous studies have been carried out to develop the visible light newlineactivity of TiO through surface modification using various noble metals Ag newlineAu and Pt as it reduces the rate of recombination of electronhole pair newlineSurface modification also results in a shift in the absorption spectrum of newlinesemiconductor to the visible range resulting in a decreased bandgap More newlineover SiO TiO composite materials were widely investigated in the newlinephotocatalysis field since the addition of SiO facilitates degradation process newlineby bringing the pollutants close to the surface of TiO through adsorption and newlinethus improves photocatalytic efficiency newlineThe present work comprises synthesis of TO silver metal newlineimpregnated TiO catalyst TiO impregnated silica composite and silver newlinemetal impregnated TiOSiO composite catalysts by solgel method All the newlinesynthesized photocatalysts were characterized by using various instrumental newlinetechniques namely UVVisible spectrometric analysis Xray diffraction newlineanalysis BET surface area Diffused Reflectance Spectrophotometric analysis newlineand Transmission Electron Microscopy From the XRD patterns of TiO calcined at different temperatures it was observed newline newline