The Research Of Solid Phase Synthesis And Property Of Titanium Dioxide Supported On Rice Husk With Sulfur Doped

Titania photocatalyst for its wide band gap, can only use the ultraviolet light which is about 4% of solar spectral range, and it’s difficult to separate the titanium dioxide from the solution after photocatalytic reaction, so its production applications is limited to some extent. To solve these above shortcomings, S-TiO2/RH composite photocatalyst was synthesized by solid state reaction method in this study, with tetrabutyl titanate used as titanium source, sodium thiosulfate pentahydrate used as sulfur source, rice husk used as carrier. Conclusions are as follows:(1) Study had compared five solid-state method of synthesizing S-TiO2/RH composite photocatalyst and their photodegradation, results indicated that the best synthesis way of synthesizing was grinding in a mortar to induce the hydrolysis reaction and loading rice husk with precursor. Preparation process:tetrabutyl titanate was grinded in a glass mortar with sodium thiosulfate pentahydrate to induce hydrolysis reaction, and then being standed, warmed, washed, and milled with pre-treatment rice husk. After tabletting and calcining, ultimately the S-TiO2/RH composite photocatalyst was generated.(2) The TiO2 photocatalyst which doped with sulfur, the absorption band edge could be moved to the visible zone, and in result owned visible light induced activity. The loading of rice husk satisfied the original properties of photocatalyst, achieved a better fixation because of the strong binding between them, and improved the dispersibility, surface area and adsorption properties of the material.(3) Calcination temperature mainly affected the crystal phase. When samples calcined at 500 ℃, it showed a significant red shift in the UV-visible spectrum, exhibited well-developed crystal without agglomeration and excellent degradation rate of dye, so 500 ℃ was chosed as the calcination temperature. When the calcination time was 4 h, sample showed maximum degree of red shift in the UV-visible spectrum and highest removal rate in the photocatalytic activity, so the appropriate calcination time was 4 h.(4) When rice husk loaded, the rare brookite phase appeared in all samples calcined within the range of 300 ℃-800 ℃. It could contribute to the large number of pores and high specific surface area of rice husk ash which the calcined product of rice husk, brookite nucleated on the phase interface and then grew gradually spread to the internal phase of anatase, phase transition from anatase to brookite could be occurred.(5) When the calcination temperature was 500 ℃, calcination time was 4 h, the crystal structure of S-TiO2/RH sample was mixed with 54% anatase phase and 46% brookite phase. The result of FTIR spectroscopy indicated Si in supporter and S in sulfur source had already entered the crystal lattice of TiO2 and formatted defect because of Ti-O-Si bond and Ti-O-S bond.(6) The results showed that when the amount of S-TiO2/RH composite photocatalyst was 1.5 g/L, the initial concentration of the solution was 20 mg/L, initial pH value of solution was 7, the photocatalytic activity of Congo red solution reached the maximum. The photocatalyst could be used repeatedly, its photocatalytic rate was not decreased after five times and owned long service life.