Study On The Influence Of Nano-TiO₂ To Degradation Of MTBE In Water

The methyl tertiary butyl ether (MTBE), as an addictive in gasoline, is used widely since the leaded gasoline has been prohibited. By some ways, MTBE can be transferred into water. Since the degradation of MTBE is very slow naturally, the pollution of MTBE in water is attracting more and more attentions. MTBE can lead to acute and chronic toxicity on living organisms, and there are apparente damage in liver, kidney, central nervous system to humans. Toxicology studies have shown that MTBE is an carcinogen in experimental animal, and also is a suspected carcinogen in human. In consideration of harm in MTBE, how to remove the MTBE from water economically and effectively has been become the focus on environmental healthy area. The degradation technologies of MTBE include mainly biodegradation, phytoremediation, physical and chemical methods, photocatalytic degradation and so on at present stage. This project attempts to study on the degradation of MTBE in water applying three forms nano-TiO₂ under the visible light condition, to observe the impact factors in degradation of MTBE, to find the best degradation conditions.In the first charpter, the sources and hazards on living organisms of MTBE, the research situation in degradation of MTBE at home and abroad, the research progresses on nano-TiO₂ photocatalysis related technologies and the purpose and contents in this paper are introduced.In the second chapter, a method in static headspace gas chromatography to detect MTBE in water was established. The influencing factors on the strength of the sensitivity including headspace equilibrium temperature water bath, heat balance of timing, flow split ratio and the choice of column, detector temperature, chromatography column temperature and injector temperature were studied to determine the optimum conditions. Under this optimum conditions, the detection limit of MTBE in water was 1.63×10-2μg/L, the linear range was 1.56×10-2～120.00 mg/L. The coefficient of correlation was 0.9997, recoveries were 92.6%～100.1% and RSD was less than 1.1%. This method of the determination of MTBE in water less interference, high sensitivity, low detection limit, simple, rapid, accurate and easy to operate and the advantages of wide linear range. The method is suitable for analyzing MTBE in water.In chapter 3: N, Ag doping of nano-TiO₂ was prepared by hydrolysis precipitation and monoclinic TiO₂ prepared by chemical complex precipitated, characterized by X-ray diffraction measurements (XRD), Transmission electron microscopy (TEM), Scanning Electron Micrograph (SEM), Thermogravimetry differentian scanning (TG-DSC).In chapter 4: Describe three kinds of nano-TiO₂ photocatalytic degradation of MTBE in water, find out the best degradation conditions. In this experiment, discuss the initial concentration of MTBE, pH, catalyst and hydrogen peroxide dosage on the MTBE degradation rate. The results showed that degradation of MTBE has high catalytic activity, the lower the initial concentration of MTBE in water, the better of the degradation among three systems. And when MTBE concentration was 10 mg/L, N, Ag doping of nano-TiO₂ catalyst was 2.0 g/L, hydrogen peroxide was 15 mmol/L, pH value is between 6 and 7, the degradation efficiency can reach 81.2% in 3 hours; monoclinic TiO₂ catalyst was 4.0 g/L, hydrogen peroxide was 10 mmol/L, pH value is between 6 and 7, the degradation efficiency can reach 84.9% in 3 hours.In chapter 5: Discuss the degradation mechanism of catalytic degradation of MTBE, using malachite green spectrophotometric indirectly detection of the reaction system whether is generated ?OH, then determine whether the degradation of MTBE in these studies is related to ?OH. The results show that: monoclinic TiO₂ degradation system because of generating ?OH.