Synthesis of Magnesium Aluminate-Grapheme Oxide Composite for Dye Removal

The aim of this research is to synthesis and modify the low cost MgAl2O4-based photocatalyst. For this purpose, MgAl2O4 was first synthesized by sol-gel combustion method and then the effect of calcination temperature on the photocatalytic performance of semiconductor was evaluated through the elimination of methylene blue. In the next step, magnesium aluminate/graphene oxide composite was synthesized by three methods; sol-gel combustion, surface grafting by APS and hydrothermal method. The obtained samples were also employed for dye degradation to understand the role of synthesis method on the composite activity. Samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and Field emission scanning electron microscopy. The photocatalytic activity was evaluated by measuring the level of MB degradation by UV spectroscopy. Results show that the presence of amorphous phase has a considerable effect on the photocatalytic performance of magnesium aluminate. Furthermore, graphene oxide nanosheets play an important role in the improvement of photocatalytic activity. Synthesis of composite by addition of graphene to the precursor, in the hydrolysis step of sol-gel combustion method, yields significantly superior photocatalytic activity compared to those synthesized by other two methods, so that 79% and 98% of methylene blue elimination could be achieved under 180 minutes of lamp and sun light irradiation, respectively.