Modified and Nonmodified TiO2 Nanoparticles for Environmental Applications

Abstract Adsorption and photocatalysis have been proposed as effective technologies for the treatment of wastewater. This review discusses the effectiveness of modified and nonmodified TiO 2 as adsorbent and/or photocatalyst for its use in wastewater treatment technologies. A disadvantage is the need of an additional separation step involving the removal of the photocatalyst from the treated water. In this respect, magnetically separable photocatalysts have been developed that enable the easy recovery of the adsorbent/photocatalyst by an external magnetic field. We review various synthetic methods for their preparation and their photoactivity toward the degradation of various substances. Another approach to obviate the need for an additional separation step is the dispersion of TiO 2 on layered clays, as the resulting composite materials sediment much faster than raw or commercial TiO 2 nanoparticles. A brief presentation of papers focused on the synthesis of TiO 2 silicate nanocomposites with environmental applications is included.