Study On Preparation And Photocatalytic Properties Of TiO₂ By Ultrasound Assisted Microwave Method

Titanium dioxide photocatalytic functional material has characteristics of high stability, non-toxic, no secondary pollution and so on, but it can only use ultraviolet photocatalytic which greatly limits its application. In order to prepare good performance photocatalyst under visible light, this paper by introducing ultrasound technology and microwave technology to improve the traditional production method, prepared excel ent catalytic performance CdS/TiO₂ composite powder. In order to determine the process parameters for preparing CdS/TiO 2, the effects of different factors on CdS/TiO₂ photocatalytic properties were investigated by photocatalytic purification experiments of methyl orange simulated wastewater. Samples were characterized by scanning electron microscopy（SEM）, X-ray diffraction（XRD）and Fourier transform infrared spectra（FT-IR）. The results were as follows:（1）Based on the microwave hydrolysis method, ultrasonic was utilized to assist reaction to prepare photocatalyst CdS/TiO₂ composite powder by using titanium isopropoxide. With methyl orange simulated wastewater, experiments were carried out to investigate the effects of the molar ratio of TiO₂ and CdS, microwave temperature, microwave time, ultrasonic power, ultrasonic time on the photocatalytic properties of the samples. When the molar ratio of TiO 2 and CdS was 25, microwave temperature was 60 ℃, microwave time was 90 min, ultrasonic power was 300 W, ultrasonic time was 45 min, the photocatalytic activity of prepared composite powders was better. Taking 0.12 g CdS/TiO₂ sample were applied in methyl orange solution that the concentration was 8 mg/L for photocatalytic degradation, the degradation rate reached 69.34% after 5 h in visible light. The prepared sample had more uniform dispersion, better crystal inity which was composed of anatase titanium dioxide and hexagonal phase cadmium sulfide.（2） Using titanium isopropoxide as raw materials, CdS/TiO₂ composite powder was prepared by ultrasonic hydrothermal method. With methyl orange simulated wastewater, experiments were carried out to investigate the effects of the molar ratio of CdS and TiO 2, the temperature of the reaction, ultrasonic power on the photocatalytic properties of the samples. When the molar ratio of CdS and TiO₂ was 1.5, the temperature of the reaction was 200 ℃, ultrasonic power was 300 W, the photocatalytic activity of prepared CdS/TiO 2 was better. Taking 0.12 g CdS/TiO₂ sample were applied in methyl orange solution that the concentration was 8 mg/L for photocatalytic degradation, the degradation rate reached 62.45% after 5 h in visible light. Composite samples were prepared showing the smooth spherical of TiO₂, the rough hexagonal block form of CdS. CdS/TiO₂ had good crystal inity which was composed of anatase titanium dioxide and hexagonal phase cadmium sulfide.