Comparative Study of Hydrogel-Based Recyclable Photocatalysts.

A series of hydrogen-based TiO2 photocatalysts were prepared by the simple entrapment of TiO2 nanoparticles in different hydrogel matrices using gelation processes. The hydrogels, namely, agarose, alginate, and chitosan, were used as matrices for TiO2 immobilization. Morphological differences were characterized for the three different hybrid gel photocatalysts. The rate of methylene blue (MB) photodegradation increased with increasing initial TiO2 dosage in all samples. The structural properties of the hydrogels significantly affected the diffusion of MB and altered the photocatalytic activities. Among these three different hybrid gel photocatalysts, the chitosan-based TiO2 membrane showed superior activity to the agarose- and alginate-based TiO2 hybrid gels. In addition, chitosan/TiO2 still showed excellent photocatalytic activity after being reused in three cycles, suggesting that chitosan/TiO2 is a new potential eco-friendly and a cost-effective photocatalyst for wastewater treatment.