The Study Of Degradation Of Methyl Tert-butyl Ether By Ultraviolet Radiation Catalyze

Methyl Tert-Butyl Ether(MTBE), as a widely used gasoline additive as well as a kind of persistent and refractory pollutant, is mainly used to replace alkyl in order to enhance octane rating of gasoline. MTBE, being used extensively, will pose a potential pollution threat to surface water and groundwater due to the increasing quantity of MTBE entering into the environment and water through various ways. At the beginning, an analytical method of Headspace—Gas Chromatography (GC) for the determination of MTBE in water sample was studied, discussing the factors influencing the determination such as equilibrium time, volume ratio of gas and liquid equilibrium temperature, etc. The experimental results showed that the recovery of MTBE falls within the range of 100±1% ,corresponding RSD within 3 % , and the lowest detection limits 0.0005 0.001mM.The application results show that headspace—GC method is accurate and rapid . On the basic of this work, degradation of MTBE in aqueous solution by UV/Fenton, UV/H₂O₂, UV/TiO₂ three advanced oxidation processes was investigated and researched carefully and systematically.(1) Degradation of MTBE in aqueous solution by UV/Fenton was investigated, and effects of reaction conditions on the oxidation efficiency of MTBE by UV/Fenton were examined in batch experiments. Under 10 mM H₂O₂, 2 mM Fe²⁺, pH 2.4 and room temperature, the initial 1mM MTBE solution could be reduced by 99 % within 30 min, the removal rate of CODcr could reach 54.7%, within 60 min. Results also showed that MTBE was decomposed in a two-stage reaction. MTBE was first decomposed swiftly based on a UV/Fe²⁺/H₂O₂ reaction and then decomposed somewhat less rapidly because of the sharp decrease of Fe²⁺.(2) Degradation of MTBE in aqueous solution by UV/H₂O₂ was investigated by a batch photo-reactor, effects of reaction conditions and anions Cl^-, HCO₃^- in aqueous solution on the degradation of MTBE by UV/H₂O₂ were examined. The results showed, under UV wavelength 254nm, 15mM H₂O₂, pH3.0 and room temperature, the removal rate of MTBE could reach 97.6% within 60 minutes, the removal rate ofCODcr could reach 46.1%, the oxidation rate of MTBE decreased with increase of the amount of Cl^- and HCO₃^-. UV/H₂O₂ process is an efficient method to remove MTBE in aqueous solution. Isobutylene and TBA are the primary products of degradation of MTBE.(3) Degradation of MTBE in aqueous solution by UV/TiO₂ was investigated by a batch photo-reactor. The result showed, under UV wavelength 254nm, 2. Og/L— 3. Og/L TiO₂, pH3.0 and room temperature, the removal rate of MTBE could reach 80% within 60 minutes and 99% within 120 minutes respectively. Besides, the removal rate of CODcr could reach 46.1% within 60 minutes. It was proved that Ag/TiO₂ was more efficient than individual process (TiO₂) under the same condition.