Preparation and performance of anatase-loaded porous carbons for water purification

Fine particles of photoactive anatase-type TiO 2 were loaded on activated carbon and carbon spheres through the hydrolysis of titanium oxysulfate under autogenous hydrothermal conditions. Their photoactivity and adsorptivity were evaluated separately by the measurements of relative concentration of methylene blue (MB) and iminoctadine triacetate (IT) remained in the solution either in the dark or under UV irradiation. Activated carbon could adsorb a large amount of MB but only a small amount of IT, and carbon spheres could adsorb only a small amount of MB. Loading of anatase under hydrothermal conditions was found to occur preferentially at the entrance of pores on the surface of substrate carbon in the beginning of deposition and to result in the reduction of specific surface area and consequently of the adsorption rate of MB. Further hydrothermal treatment was found to give homogeneous coverage of the surface of activated carbon by anatase fine particles. By UV irradiation after the saturation of adsorption in the dark, a marked decrease in concentration of MB and IT was observed, which recovered a high adsorptivity of activated carbon. Through repetitive measurements of concentration decrease in the solution in the dark and under UV irradiation, it was proved that MB and IT, which were adsorbed in the dark, could be decomposed under UV irradiation.