Removal of phenol in aqueous media by N-doped TiO2 based photocatalytic aerogels

In this work, composite monolithic aerogels based on syndiotactic polystyrene (s-PS) and N-doped TiO2 (NdT) photocatalyst characterized by high surface areas (up to 280 m2/g) and low density (0.1 g cm−3) are presented. These aerogels are obtained by supercritical carbon dioxide extraction of NdT/s-PS gels prepared by s-PS dissolution with NdT in suitable organic solvent. X-ray diffraction measurements and SEM analysis showed that a highly efficient dispersion of NdT nanoparticles can be achieved in the composite aerogels avoiding thus the aggregation phenomena that typically occur when the photocatalyst is used in slurry reactors. The optimization of NdT amount dispersed in s-PS was evaluated using phenol as model pollutant both under UV and visible light irradiation. The photoactivity of NdT/s-PS samples increased with increase of the amount of NdT dispersed in aerogel matrix up to NdT/s-PS weight ratio equal to 10/90 (10NdT/s-PS), for which the highest phenol degradation and TOC removal were achieved both under UV and visible light irradiation. Moreover, the photocatalytic activity of the optimized photocatalyst 10NdT/s-PS did not change significantly after several reuses underlining that any NdT particles are removed from the polymeric matrix.