Influence of TIO2-rGO optical properties on the photocatalytic activity and efficiency to photodegrade an emerging pollutant

[Display omitted] •TiO2-rGO optical properties were estimated using the Monte Carlo method.•TiO2-rGO exhibited higher scattering coefficients than TiO2.•rGO was found to increase quantum efficiency of bare TiO2.•Complete degradation of clofibric acid was achieved after 6 h of irradiation time. TiO2-reduced graphene oxide (TiO2-rGO) photocatalysts with different mass ratios (GO:TiO2 0.1-0.5-1%) were synthesized via a hydrothermal method and compared through their physico-chemical properties and photocatalytic activity in the degradation of an emerging contaminant, clofibric acid. The optical properties of the TiO2-rGO nanocomposites were first estimated in order to calculate the local volumetric rate of photon absorption inside a photocatalytic reactor. Radiation models were solved using the Monte Carlo method. The effect of rGO as well as the photocatalyst loadings on the radiation absorption was evaluated. The lowest photodegradation rate found in P25-rGO 1% was ascribed to an excess of rGO that could well favor charge carriers recombination leading to detrimental photoactivity. A GO/TiO2 mass ratio of 0.5% provided the fastest initial photodegradation rate under the operating conditions studied here. Finally, the photo-efficiency of all these photocatalysts was also analyzed by calculating the quantum efficiency parameter. The highest value of quantum efficiency was achieved with P25-rGO 0.5% at 100 mg L−1, with an increase of 11% compared to the value obtained for P25-rGO 0%.