Preparation of renewable porous TiO_2/PVA composite sphere as photocatalyst for methyl orange degradation

摘要

Firstly, preparation of porous polyvinyl alcohol (PVA) spheres were investigated in detail by phase inversion method using N,N-dimethylacetamide (DMAc) and polyvinylpyrrolidone (PVP) as pore-forming additives. The morphology and pore structure of PVA spheres were characterized by SEM and BET measurements. It was found that the addition of DMAc and PVP increased the pore volume and the surface pore size of PVA sphere respectively. The maximum surface area of the porous PVA sphere reached 220 m(2)/g. Secondly; the synthesis of photoactive TiO2 NPs (anatase type) at the low temperature was developed by controlling the aging process of the TiO2 precursors. The crystallinity and photoactivity of TiO2 NPs increased with the aging time. Finally, TiO2 NPs/PVA composite spheres were prepared by immersing PVA sphere into TiO2 precursor solution. Their structures were characterized by XRD pattern, TEM and TGA measurement. It was found that TiO2 NPs were successfully immobilized into PVA spheres. The photodegradation of methyl orange (MO) under UV light by TiO2/PVA spheres showed a good photocatalytic efficiency. Moreover, TiO2/PVA spheres can be easily regenerated by the repeated immersion process. Overall, the porous TiO2/PVA sphere displays a good photoactive property and an advantage of easier recovery, which facilitates its application in large-scale wastewater treatment.