| The photocatalytic degradations of Methyl tert-Butyl Ether (MTBE) and 2-isopropylphenyl-N-methylcarbamate (MIPC) were studied and the reaction schemes were presumed by using GC-MS, HPLC, FTIR, IC and UV-Vis spectra. The effects of initial concentration(C0) of reactant, the amount of catalyst,coexistence metal ion, pH and light intensity(I) on photodegradation of MTBE and MIPC have been investigated. The results showed:MTBE was photocatalytically transformed to innocuous products and mineralized ultimately in oxygenated TiO2 slurries. The major intermediates of this reaction had been identified as t-butyl formate,t-butyl alcohol, and acetone, all of which were also readily degraded photocatalytically, albeit at different rates. Based on identification of intermediates and final products, the first step in the destruction of MTBE was thought to be abstraction of a α-hydrogen by ·OH and a reaction scheme was proposed. The degradation rate of MTBE depended on the amount and calcined temperature of catalyst, and the optimum concentration and calcined temperature of catalyst were 0.5g/L and 400 ℃, respectively. However, the degradation rate of MTBE was independent of its initial concentration and solution pH in our experiment. MIPC was photocatalytically transformed to 3,4-dihydroxyl hypnone, 2-iso-butyl phenol and acetic acid, and mineralized ultimately in oxygenated TiO2 slurries. The photocatalytic degradation processed according to first order kinetics with the apparent rate constant depending on initial concentration, light intensity and the amount of catalyst. The amount of catalyst had an optimum value (0.5g/L). The apparent rate was inversely proportional to square root of the initial concentration approximately. Furthermore, the apparent rate constant was proportional to light intensity, and affected by coexistence metal ion, especially the existence of Cu2+ inhibited the degradation of MIPC. Based on our experiment, a kinetics empirical equation was proposed.
|
PDF Full Text Request