Preparation, Characterization And Photocatalytic Properties Application Of TiO₂-SiO₂/C Driven By Visible Light

The photocatalytic technology, represented by TiO₂, was considered as an ideal method to deal with environmental pollution, and an important way to solve the global energy crisis. However, it limits practical application of TiO₂ due to its low photocatalytic activity and utilization of solar energy. Under this background, it is of self-evident practical significance and use value to research and develop a new type photocatalytic material with high efficiency and utilization of solar power.The TiO₂-SiO₂/C composite photocatalyst driven by visible light with high activity was prepared by an Evaporation induced self assembly technology in this work, by using tetrabutyl titanate and tetraethyl orthosilicate as the main raw materials, L-isoleucine as carbon source and coupling agent. The element composition, badgap, crystal structure, morphology, partical size of the composite photocatalysts are analyzed by a series of characterization methods, such as XPS、UV-Vis、XRD、TEM、BET、FT-IR, and the formation mechanism of TiO₂-SiO₂/C is explored. The influence of different process conditions on the photocatalytic performance is studied to optimize the process parameters, and then an efficient and green photocatalytic technology can be obtained for the treatment industrial wastewater. The results were as follows:1) The formation mechanism of TiO₂-SiO₂/C composite photocatalyst is: the oxygen atom is substituted by some carbon atoms in the lattice of TiO₂, to form the Ti-C or Ti-O-C bond. The other carbon coated the outer layer of TiO₂ and SiO₂, which formed porous carbon covered on the surface of particles. The Si of dopants incorporated into TiO₂ and TiO₂ was linked by chemical bonds, be ascribed to the bond of Ti-O-Si. A small part of amorphous SiO₂ gathered around the TiO₂ grain boundaries. Analyzing the characterization of the sample, which the bandgap was 2.79 eV, the particle size was 4.69 nm, and specific surface area was 529.46 m2g-1. Samples still keeping anatase phase by 600℃ heat treatment.2)Photocatalysis degrades Rhodamine B solution, the effects of carbon doped concentration, pH, calcination temperature on the photocatalytic performance were investigated. The effects of the photocatalytic efficiency with the stability and usage amount of composite photocatalyst were also investigated. The results showed that degradation rate of the sample reached 90.46% in highest, when the visible light irradiation 80 min, carbon doped concentration was 0.4, pH was 1.5, the temperature was 450℃, the usage was 0.05 g. After six times of recycling, the degradation rate was kept into 89-90%,which showed that the sample has good stability.3)Photocatalysis restores Uranium ion solution, the effects of pH, shocking time, reaction temperature, and usage of composite photocatalyst on the Uranium ion removal rate were investigated, and characterized, discussed the removal rate of Uranium ions is photocatalytic reduction reaction whether or not. XPS analysis showed that after the photocatalytic reaction, the U（VI） ion in the Uranium ion solution was adsorbed firstly, then through photocatalysis, it can be reduced to the U（IV）. The results showed that the pH was 6, shocking time was 30 min and the usage was 1.0g, the removal rate can reach 96.7% in highest.