Synergy mechanism for TiO2/activated carbon composite material: Photocatalytic degradation of methylene blue solution

To improve the photocatalytic effect of TiO2 and the possibility of recycling, three different types of commercial activated carbon (AC) are used to prepare the TiO2/AC composite photocatalyst using the sol-gel method. The properties and catalytic activity of TiO2/AC composite are evaluated in comparison with bare TiO2, based on several characterization techniques and methylene blue (MB) photodegradation studies. The results show that the addition of AC improves the degradation effect of MB. The TiO2/AC-(L) composite material has the best photocatalytic effect. The efficiency of removing the MB solution in 60 min reaches 99.43% at the initial concentration of MB 20 mg/L and material dosage 400 mg/L. The synergy between the adsorption characteristics of the AC surface and the photocatalytic activity of TiO2 is the main reason for increasing the MB degradation rate. Hydroxyl radicals play a major role in the process of photocatalysis. The addition of AC enhances the formation of hydroxyl radicals and superoxide radicals, thereby improving the photocatalytic performance of the material. Compared with bare TiO2, the three TiO2/AC composite photocatalysts can maintain excellent photocatalytic effect after four cycles of experiments and are easier to recycle and reuse.