Study On Preparation And Properties Of TiO₂by Ultrasound/Microwave-assisted Sol-gel Method

Titanium dioxide is the most promising, environment-friendly and resource-conservingphotocatalytic material. In order to change the traditional photocatalysts synthesis process, tofurther improve the photocatalytic activity of TiO2, this paper used ultrasonic and microwavetechnology to improve synthesis method and experiments were conducted to explorepreparation method of TiO2photocatalyst. A variety of characterization methods were carriedout, such as scanning electron microscopy, X-ray diffraction and Fourier transform infraredspectra, to test surface morphology and crystal structure of the samples. The effects ofdifferent factors on TiO2photocatalytic properties were investigated by photocatalyticpurification experiments of contaminants methyl orange and formaldehyde using preparedsamples. The results are as follows:(1) Based on the sol-gel method, ultrasonic and microwave were utilized to assistreaction to prepare photocatalyst TiO2using titanium isopropoxide as precursor. Experimentswere carried out to investigate the effects of reaction time under ultrasound and microwaveconditions, ultrasonic power and microwave power on the photocatalytic properties of thesamples. When reaction time was1.5h, ultrasonic power300W and microwave power300W,photocatalytic activity of TiO2prepared was the best, and photocatalytic degradation rate ofmethyl orange solution reached more than60%after3h in xenon lamps simulating solar light.Through SEM, XRD and FT-IR characterization it was showed that TiO2prepared wasanatase, most particles were spherical shape and had better crystallinity, more uniformdispersion and smaller particle size. Amount of catalyst and initial concentration of reactantwould affect the degradation efficiency of methyl orange. When amount of catalyst was1.0g/L, initial concentration of the reactant was8mg/L, the degradation rate of methyl orangereached64.89%.(2)Using titanium isopropoxide, cadmium chloride and thiourea as raw materials, CdS/TiO2was prepared by ultrasonic hydrolysis. By orthogonal experiment, theimpact of molar ratio of CdS/TiO2on the photocatalytic properties was greatest, followed byultrasonic time, and then followed by mixing reaction time, mixing reaction temperature withminimal impact. When the CdS/TiO2molar ratio was0.75, ultrasonic time30min, reactiontime90min, and reaction temperature was70℃, the photocatalytic activity of the dopedsample prepared was the best, and the degradation rate of formaldehyde by photocatalyticpurification reached40.12%after180min in the simulated solar light. Through SEM, XRDand FT-IR characterization it was showed that the sample prepared was composed of anatasetitanium dioxide and cubic and hexagonal phase cadmium sulfide.