| Summary: | 碩士 === 國立中興大學 === 環境工程學系所 === 98 === Methyl tert-butyl ether (MTBE) is used primarily as a gasoline oxygenate. Due to low octanol water partition coefficient (Kow) and high water solubility, MTBE once accidently released in subsurface may contaminate groundwater. Permeable reactive barriers (PRBs) filled with reactive materials could intercept and decontaminate the polluted groundwater plume in the subsurface. Activated carbons (AC) adsorption is a suitable reaction mechanism for PRBs. However, once the filled ACs is exhausted, it is required to replace the spent AC with new materials. Therefore, it is desired to regenerate spent AC in situ and hence to reduce the cost for AC replacement. In situ chemical oxidation (ISCO) oxidant persulfate (S2O82-) and its activated product known as the sulfate free radical (SO4-•) exhibit capability of destroying organic contaminants. Therefore, the goal of this study was to evaluate the degradation of MTBE by persulfate and investigate the potential of using persulfate for regeneration MTBE spent AC. All experiments were carried out in batch mode. The results show that persulfate can desorb MTBE from spent AC. However, upon contacts between AC and persulfate, acidic functional groups would be produced on the AC to interfere adsorption of MTBE. Pyrite (FeS2) is a natural ferrous ion bearing mineral which can slowly release Fe2+ to activate persulfate to form SO4-•. It has been identified that pyrite activated persulfate oxidation can effectively oxidize MTBE and the reaction pathway undergoes α-abstraction process. Furthermore, the observed intermediates upon MTBE degradation include: tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone, and methyl acetate (MA). Spent ACs regenerated by pyrite activated persulfate exhibits a better readsorption of MTBE than those regenerated by persulfate only.
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