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.