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Interest has grown in the modification of titanium dioxide with graphene to improve the photocatalytic behaviour. In this work, titanium dioxide–reduced graphene oxide (TiO 2 –RGO) composites were synthesised by the photocatalytic reduction of exfoliated graphene oxide (GO) by TiO 2 (Evonik P25) under UV irradiation in the presence of methanol as a hole acceptor. The composite materials were characterised using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman and XPS analysis provided evidence that GO was converted to RGO by photocatalytic reduction. The TiO 2 –RGO composites were compared to TiO 2 in suspension reactors for the disinfection of water contaminated with Escherichia coli and Fusarium solani spores under real sunlight. Very rapid water disinfection was observed with both E. coli and F. solani spores. An enhancement in the rate of inactivation of E. coli was observed with the TiO 2 –RGO composite compared to P25 alone. The rate of inactivation of F. solani spores was similar for both the TiO 2 –RGO and P25. When the major part of the solar UVA was cut-off ( λ > 380 nm) using a methacrylate screen, there was a marked increase in the time required for inactivation of E. coli with P25 but no change in the inactivation rate for the TiO 2 –RGO. There is evidence of singlet oxygen production with visible light excitation of the TiO 2 –RGO composites which would lead to E. coli inactivation. [ABSTRACT FROM AUTHOR]

Agricultural wastewater is characterized by high organic matter and traces of organic pollutants. Effluents from the agro-food industry in particular are a potentially high environmental risk which requires appropriate, comprehensive treatment. This study evaluated the treatment of real wastewater from an agro-food processing plant by an Immobilized Biomass Reactor working in batch and continuous operating modes. Organic matter oxidation and the removal of reference organic pollutants were analyzed. Finally, the efficiency of a photocatalytic tertiary treatment with supported TiO 2 for the IBR effluent containing persistent microcontaminants was also studied. After the combined treatment, imazalil and thiabendazole were completely removed and over 90% of acetamiprid had been eliminated, but only with the additional contribution of hydrogen peroxide as an electron acceptor. [ABSTRACT FROM AUTHOR]