Adsorption and photocatalytic degradation are considered as the most important ways of treating water from organic compounds. It would be very useful if the adsorption and photocatalytic properties are combined in the same catalyst used in the treatment. Titania is one of the best well-known photocatalysts. However, due to its poor selectivity, it is unfavorable for photocatalytic removal of highly toxic low-level organic pollutants in wastewater in the presence of other less toxic high-level pollutants. Recent trials to introduce selectivity for titania have been achieved via controlling the catalyst morphology or by modifying the catalyst surface. This chapter summarizes the control of selectivity of titanate nanostructures toward adsorption and/or photocatalytic degradation of toxic organic dyes. In the first part, the effect of morphologies of titanites on selective photocatalytic degradation of three food dyes (color yellow sunset, red allura, and red carmoisine) was discussed. In changing the morphology of titanite, each dye is being preferably adsorbed by one morphology and decomposing more rapidly. In the second part, the selective adsorption and/or photocatalytic degradation of methylene blue dye from mixed dye solution using sodium titanate (NaTNT), cobalt-doped titanate nanotubes (co-doped TNT), and the decorated one with gold nanoparticles has been discussed.
Part of the book: Photocatalysts