| Methyl tert-butyl ether (MTBE) is currently the leading contaminant of groundwater in the United States. The widespread presence of MTBE along with its degradation by-product, tert-butyl alcohol (TBA), in groundwater has created great concern in the scientific community because MTBE and TBA are suspected as possible human carcinogens. In this research, the degradation of MTBE and TBA in aqueous solution by O3/UV process has been investigated. Laboratory studies were conducted using a semi-batch reactor under various experimental conditions, i.e., incident UV light intensity, influent ozone gas concentration, and water quality in terms of varying bicarbonate concentration.; Furthermore, the O3/UV process was modeled by using oxalic acid as a probe chemical. Oxalic acid was oxidized by O3/UV process under various experimental conditions; and the model successfully predicted the residual concentration of oxalic acid. In order to understand the degradation mechanisms of MTBE and TBA, a comprehensive kinetic model that describes the degradations of MTBE, TBA and their intermediates by O3/UV process was proposed. The model was calibrated using experimental data on MTBE and TBA spiked in synthetic solution. An attempt was made to verify the kinetic model using different sets of experimental data. The model predicted well the removal of MTBE and TBA; however, the accumulation and decay of some primarily intermediates were predicted with slight variations.; Finally, real groundwater samples contaminated with MTBE and TBA were oxidized by O3/UV process under various experimental conditions. It was observed that the removal rate of MTBE and TBA was reduced by the presence of other gasoline components, such as BTEX. Furthermore, for groundwater sample without iron the kinetic model predicted the degradation of MTBE as well as accumulation and decay of reaction intermediates with slight variations.; In conclusion, this research provides valuable information on the degradation mechanisms of MTBE, TBA, and their intermediates. The O3/UV process was very successful in degrading MTBE and TBA in aqueous solution. Moreover, it was observed that the reaction intermediates react well in the O3 /UV process, and complete mineralization could be achieved, if desired. |
