Photocatalytic activity of TiO2 nanofibers in simulated and real municipal effluents

Improvement of photo-oxidation efficiency and separation ability of photocatalysts is a challengeable issue for the application of TiO2-based technology in water treatment. A recently developed H-titanate nanofiber (NF) was proven to be a promising catalyst. In this study, adsorption and degradation performances of the NF and commercial Degussa P25 (P25) catalysts were assessed in a laboratory scale photo-reactor. Matrix effect on the photocatalytic degradation of two different compounds, the anionic azodye Congo Red (CR) and the recalcitrant pharmaceutical Carbamazepine (CBZ), was studied in saline water and real municipal effluent. Dark adsorption of CR appeared to be higher in real effluents than in saline water, while CBZ adsorption was negligible in both the matrixes. The two catalysts showed similar photocatalytic activity in saline water and MBR effluent. Opposite matrix effects were found for the degradation of the two model compounds, and the degradation selectivity strongly depended on the initial adsorption step. A weak influence of different anions, but a strong influence of the divalent calcium was found in the photocatalytic system using NF catalyst. The negative influence of the organic substances in the real effluent was proved to remain stable in repeated tests.