Study On Preparation And Properties Of Nano-TiO₂ Composite Photocatalyst Supported On Fly Ash Microsphere

Titanium dioxide（TiO₂）is the most widely used typical semiconductor photocatalytic material.The effective way to solve the problems of particle agglomeration and reuse is to load nano TiO₂ on the surface of the carrier,among which fly ash micro beads have some advantages and development prospects.In order to improve the carrier function,realize the material and high value-added utilization of fly ash micro beads,the composite photocatalyst was prepared by surface treatment and nano TiO₂ loading on the surface of the treated fly ash micro beads,The preparation process and the properties of the composite photocatalyst were studied.The composite photocatalyst supported by TiO₂（commercial p25）on the surface of the micro beads was prepared by wet grinding method,and the structure,morphology and properties of the composite photocatalyst were studied.The degradation rate of methyl orange solution was100%under UV light for 15 minutes.Compared with nano TiO₂,the degradation ability of methyl orange was the same.The fly ash micro bead carrier has a positive effect on improving the dispersion and saving the actual use amount while not destroying the structure of nano TiO₂crystal.The surface roughness of the micro beads was significantly increased,and the impurities and hydroxyl number of the beads were increased,which provided favorable conditions for the nano TiO₂ loaded on the beads.Compared with the two etching methods of HCl and NaOH solution,the surface morphology of the micro beads treated with HCl has more obvious etching effect.The composite photocatalyst was prepared by sol-gel method with nano TiO₂ on the surface of the fly ash beads treated by HCl and NaOH etching respectively.The composite photocatalyst has good photocatalytic degradation ability for methyl orange solution,and is significantly better than that of nano TiO₂ composite photocatalyst supported by micro beads without surface treatment.Under the optimized conditions,the degradation rate of methyl orange solution by UV irradiation for 60 min was 97%,twice that of the untreated samples.The degradation rate of 10ppm methyl orange was 97%and the initial concentration was 39%in 60 minutes.The structure,morphology and mechanism of nano TiO₂ composite photocatalyst supported by fly ash beads were studied by acid-base etching.The results show that TiO₂ is loaded on the surface of the micro beads as nanoparticles and is combined with the micro bead carrier by Si-o-Ti bond.UV Vis DRS and XPS showed that nano TiO₂ supported by micro beads can not only increase the absorption of TiO₂ to UV,but also effectively inhibit the recombination of photogenerated electron hole pairs.