Fixed-bed reactor packed with pumice-supported TiO2 for the treatment of polluted water by solar-driven photocatalytic oxidation.

A bench-scale tubular photo-reactor was built to evaluate the solar-driven TiO2-based photocatalytic degradation of synthetic polluted water samples. The reactor was designed as a compound-parabolic-collector and operated in batch mode using TiO2 P25 immobilized on a bed of pumice. The immobilization of TiO2 on pumice was carried out using a facile dip impregnation method followed by heat treatment. The obtained material was characterized by SEM, EDS, XRD, and nitrogen adsorption. It was possible to impregnate up to 68.5 mg of TiO2 per gram of pumice stones of 8-14 mm. Conversions of up to 35-40 and 62-69%, after 4 h of treatment and UV doses of 20.8 ± 3.5 kJ L-1, were achieved when the catalyst was used immobilized on pumice stone and in the form of a suspension, respectively. The stability and reusability of the catalyst-coated support was tested through a series of consecutive photocatalytic experiments. After four consecutive runs, the immobilized catalyst showed a decrease in its photoactivity leading to removal levels of 23%.