Preparation And Property Of Suspended Core （TiO₂）/Shell （SiO₂） Structure Photocatalytic Reactor

With the development of industrialization, environmental pollution problemsbecome more and more serious which call for an economical and practical techniquesto treat with. TiO2photocatalyst has raised utmost concern because of its nontoxicity,strong oxidizing power under UV irradiation, stable physical and chemical properties.After decades of research, the technology has become increasingly mature, mainlyused in water treatment, organic pollutants and landfill leachate. However, there arestill some problems to overcome in industrial applications, such as low efficiency,secondary pollution problems caused by the degradation process.Owing to these existing problems, we need further research to explore moreconvenient and practical solution. On the basis of mature technology for preparationof TiO2@@SiO2core-shell nanoparticle in our laboratory, we useoctadecyltriethoxysilane (ODTS) to prepare air-water interface photocatalyst(TiO2@@SiO2-O). After modification, TiO2@@SiO2-O nanoparticles can still bestably suspended between the water-air interface after ultrasonic treatment or UVirradiation. Then we use them to degrade methyl orange dye. Characterized by gasspectroscopy, UV-visible spectroscopy and total organic carbon (TOC) analysis,methyl orange solution can be completely degraded. In addition, TiO2@@SiO2-Onanoparticles can also effectively degrade high concentration of industrial landfillleachate.We use different silane coupling agents to modify TiO2@@SiO2nanoparticles.The results show that octadecyltriethoxysilane (ODTS) is the best grafting chainsegments with the contact angle reached to111.4°. Then we focused on its mechanismof degradation of Rhodamine B. By adsorption and degradation experimental research,we found that the bore diameter of particles has been reduced and the concentration ofthe dye has been decreased. Therefore, we speculate the degradation mechanismaccording to the results. But the specific degradation process needs to be furtherverified.Since the space of hollow layer in TiO2@@SiO2core-shell nanoparticles is small (2-3nm), we can not further study the adsorption in cavity. So it is very necessary toexpand this system. Firstly, monodisperse TiO2spherical particles with uniform sizewere prepared by a sol-gel process using tetrabutyl titanate as a titanium precursorand ehylene glycol as a chelating agent. The synthetic condition of water content inacetone, the amount of ethylene glycol, aging time and calcination were discussed andthe optimum conditions for the uniform spherical TiO2particles were confirmed.Based on the spherical TiO2particles, we prepared TiO2@@SiO2core-shellspheres by the hydrothermal method and stober method. Then we discussed someinfluence factor, such as the concentration of the glucose solution and the amount ofTEOS. Finally, the optimal experimental condition was determined: concentration ofglucose was0.1M and the amount of TEOS was1.5mL. Through characterization, theresult show that the size of TiO2@@SiO2core-shell spheres is about500nm, thespecific surface area is44.5m2/g, SiO2shell thickness is about40nm and the borediameter is4nm.