Photocatalytic oxidation process for the removal of methyl tert-butyl ether(MTBE)from highly contaminated water

摘要

The oxygenate methyl tert-butyl ether(MTBE)is added to gasoline to increase the octane level and to reduce carbon monoxide and hydrocarbon emissions by vehicles.The high mobility,water solubility,and resistance to natural attenuation associated with MTBE may result in contamination of ground and surface waters.In this research the degradation of aqueous MTBE at relatively high concentrations was investigated by UV-vis/TiO2/H2O2 photocatalytic process.The effect of important operational parameters such as pH,amount of H2O2,catalyst loading,and irradiation time were also studied.Concentrations of MTBE and intermediates such as tert-butyl formate(TBF)and tert-butyl alcohol(TBA) were measured over a 180 min period using a gas chromatograph equipped with flame ionization detector and combined with headspace sampler.Results showed that the time required for complete degradation increased from 30 to 180min,when the initial concentration was increased from 10 to 500meg/L.The first order rate constant for degradation of MTBE from the hydroxyl radical was estimated to be 0.177 to 0.022 min-1 as the concentration increased from 10 to 500 mg/L.Study on the overall mineralization monitored by total organic carbon(TOC)analysis showed that in the initial concentration of 100 me/L,MTBE.complete mineralization was obtained after 110 min under UVvis/TiO2/H2O2 photocatalytic process.The last objective of the present study was to investigate the degradation efficiency of MTBE in an actual gasoline contaminated water,obtained from drainage water of a gas station in Zanjan city.