Chemical Oxidation of MTBE and TBA

摘要

Methyl tertiary butyl ether (MTBE) is a synthetic chemical that was historically used as an octane booster additive to gasoline. Increasingly, there have been concerns about its toxicity and potential carcinogenicity. Because of these concerns, 18 states regulate MTBE levels in groundwater and 17 have banned its use in gasoline. Because of its chemical characteristics, MTBE-contaminated sites are difficult to remediate. MTBE readily dissolves and spreads in water. Additionally, MTBE resists biodegradation, does not sorb to soil, and has a low Henry's Law constant. As a result, the extent of MTBE contamination is usually much greater than that of the other common gasoline components. Because of these factors, remediation of MTBE-impacted groundwater can be very difficult and costly.MTBE can breakdown in groundwater to form tert-butyl alcohol (TBA). TBA is also an impurity in or is formulated with MTBE. Many states are also beginning to regulate TBA in groundwater. The problem of remediating groundwater contaminated with MTBE is complicated by the presence or formation of TBA. There is considerable interest in finding an efficient technology that can be used for remediation of MTBE. The utilization of in situ chemical oxidation (ISCO) is becoming a more common method for treatment of MTBE. Previous case studies and research have shown that a variety of oxidants will reduce concentrations of MTBE. However, the production of tertiary TBA with many of these oxidants poses a significant problem. Fenton's reagent, permanganate, ozone, and uncatalyzed persulfate all produce TBA. The oxidation of MTBE by activated persulfate does not generate much TBA. Additionally, activated persulfate will also oxidize TBA, if it is present.