Trapping and decomposing of color compounds from recycled water by TiO_2 coated activated carbon

摘要

Five types of commercially available activated carbons (ACs) were coated with TiO_2 nanoparticles prepared using a sol-gel method. Color and trace organics remaining in the actual treated effluent were adsorbed by TiO_2 coated ACs. The absorbed organic compounds were then decomposed using a photo-catalytic process, and the ACs were regenerated for reuse. The efficiency of the process was assessed by the characterization of true color and A_(254) (the organics absorption at the wavelength of 254 nm) at the beginning and the end of the experiment. The effects of UV light source, UV irradiation time, hydrogen peroxide and ultrasound on the efficiency of photocatalytic regeneration were also investigated. Significant differences in the efficiency were observed between uncoated ACs and TiO_2 coated samples. Among the 5 types of ACs tested, AC-3, AC-4 and their coated ones achieved better efficiency in color and A_(254) removal, with around 90% or more color and A_(254) being removed within 1 h of treatment. The data obtained in this study also demonstrated that the photocatalytic process was effective for decomposing the adsorbed compounds and regenerating the spent TiO_2/AC-3. Finally, it was found that this regeneration process could be greatly enhanced with the assistance of H_2O_2 and ultrasound by reducing the required regeneration time.