Preparation of Porous and Recyclable PVA-TIO2HYBRID Hydrogel

Abstract

Nano TiO2, one of the most effective photocatalysts, has extensive use in fields such as air purification, sewage treatment, water spitting, reduction of CO2, and solar cells. Nowadays, the most promising method to recycle nano TiO2during the photocatalysis is to immobilize TiO2onto matrix, such as polyvinyl alcohol (PVA). However, due to the slow water permeability of PVA after cross-linking, the pollutants could not contact with nano TiO2photocatalyst in time. To overcome this problem, we dispersed calcium carbonate particles into a PVA-TiO2 mixture and then filmed the glass. PVA-TiO2-CaCO3 films were obtained by drying. Through thermal treatment, we obtained the cross-linked PVA-TiO2-CaCO3 films. Finally, the calcium carbonate in the film was dissolved by hydrochloric acid, and the porous PVA-TiO2 composite photocatalyst was obtained. The results show the addition of CaCO3 has no obvious effect on PVA cross-linking and that a large number of cavities have been generated on the surface and inside of porous PVA-TiO2 hybrid hydrogel film. The size of the holes is about 5-15μm, which is consistent with that of CaCO3.The photocatalytic rate constant of porous PVA-TiO2 hybrid hydrogel film is 2.49 times higher than that of nonporous PVA-TiO2 hybrid hydrogel film.

Keywords: Hybrid Hydrogel, Photocatalysis, TiO2, PVA