Photocatalytic degradation of orange II by TiO2 catalysts supported on adsorbents

TiO2 mediated semiconductor photocatalysis is an established advanced oxidation process for the treatment of contaminated aqueous and gaseous streams. However, TiO2 exhibits low adsorption ability, especially for non-polar substances due to its polar structure. Low adsorption ability of non-porous TiO2 particles can be improved by surface augmentation using inert supports. In this work, TiO2 was impregnated on three different kinds of adsorbents, mesoporous (MCM-41), microporous (β-zeolite) and pillared structure (montmorillonite) where different loadings (10–80%) of TiO2 were obtained using sol–gel method. The catalysts were characterized by several analytical techniques including XRD, SEM–EDX, XPS, and BET analyzer. Subsequent to the dark adsorption studies, photocatalytic efficiency of the supported catalysts was evaluated using an azo-dye, orange II in water as model compound under different operating conditions. All supported catalysts exhibit good photodegradation efficiency of orange II, and their overall removal efficiency was always better than that of bare TiO2 produced by the sol–gel method and commercial catalyst, Degussa-P25.