Preparation And Performance Evaluation Of High Efficiency Composite TiO₂ Photocatalyst

Nanosized titania powder was prepared by sol-gel and hydrothermal precipitation method in the study. Effects of several factors such as reactants ratio, hydrolyzation temperature and calcinations temperature, on the particle size, surface area, crystal type and photocatalytic performance of the titania powder were investigated by orthogonal experiment method. Fly coal ash- polystyrene microspheres carrier with the size of 0.1～10 mm was prepared through suspension polymerization. Through grafting and mineralization on the substrate, the nanosized titania film was anchored on the surface of the microspheres, and the modification of visible light photocatalytic was studied through high conducting polyaniline doping. A simulated wastewater with formaldehyde was used to test the photocatalytic performance of the nanosized TiO₂, and the effects of the activity of carriers and the conducting polyaniline doping on the photocatalytic performance were studied. The crystal phase, grain size and morphology of the prepared powders were studied by infra-red, XRD, SEM and surface area techniques. The results revealed that the particles were well distributed in the surface of the support and the equality of the particle sizes was very good . The particle diameter ranges from 30 to 60 nm. It was also found that high conducting polyaniline doping could improve the nanosized TiO₂ catalyst's utilization efficiency of sun light.. The diameter of particles prepared by this method could be well controlled. Results indicated that some characteristics of the fly coal ash, for example, its large surface area, high adsorption capability, and transition metal such as Fe component, could improve the nanosized TiO₂ catalyst's photocatalytic performance significantly. The fibrous structure of the polymer surface was formed between the carrier and photocatalyst through grafting technology. The adsorption of the nanosized TiO₂ was improved and the application time was also extended. The study provided a solution for some problems encountered in the immobilization and reuse of nanosized TiO₂, facilitating the industrialization and commercialization of the nanosized TiO₂ photocatalyst.