Enhancing photocatalytic degradation of methylene blue by mixed oxides TiO2/SnO2/CeO2 under visible light

Abstract

This study focus on modification of TiO2 with a mixture of SnO2 and CeO2 that can actively degrade methylene blue as industrial dye under visible light. The synthesis of mixed oxides SnO2/CeO2/TiO2 was carried out by the precipitation method which included dissolving the reactants using HNO3 and re-precipitation with NaOH solution. The precipitate was then dried and calcined at 650 °C. The calcined products were characterized by XRD, DRUV, FTIR, SEM-EDX, TEM, and photoluminescence spectroscopy. The addition of both SnO2 and CeO2 can decrease the bandgap of TiO2 and inhibit the recombination process. The results showed that the photodegradation of MB under visible light using mixed oxides SnO2/CeO2/TiO2 was higher than that of TiO2, SnO2, and CeO2. The preparation of mixed oxides SnO2/CeO2/TiO2 using Sn/Ce ratio of 1:1 showed the highest photodegradation of MB up to 87%. The optimum conditions for the photodegradation of 40 ppm of MB were obtained at pH 7, with 0.2 g of catalyst mass, and 120 min of reaction time. The photocatalytic mechanism of the SnO2/CeO2/TiO2 mixed oxides was obtained up to three runs without appreciable loss of activity and shows great potential to be an excellent candidate for environmental remediation.