HYDROLYSIS OF MTBE: IMPLICATIONS FOR ANAEROBIC AND ABIOTIC NATURAL ATTENUATION

摘要

Methyl tertiary-Butyl Ether (MTBE) is generally considered to be resistant to chemical transformation in the aqueous phase. This lack of reactivity has lead to concerns of the long term impacts of MTBE in groundwater. Although hydrolysis has been recognized as a mechanism for MTBE transformation, it has been discounted as a significant reaction under environmental conditions. This idea is reinforced by the chemical literature that indicates alkyl ethers are only sensitive to hydrolysis under strongly acidic conditions. In this study, we have examined the fate of MTBE and other ether oxygenates under moderately acidic conditions (≥ pH 2). Our results demonstrate that MTBE is sensitive to acid-catalyzed hydrolysis reaction that generates tertiary butyl alcohol and methanol as products. The transformation rate decreases with pH and increases with temperature. A rate of 1 X 10~(_3) d~(-1) was measured at pH 2 and 25℃. The results will be discussed in terms of the potential implication for the natural attenuation of MTBE. A hypothesis of abiotic soil catalyzed hydrolysis will be presented. Hydrolysis also has implications for microbial degradation. Although oxygenase enzymes are typically responsible for MTBE transformation in aerobic organisms, these findings suggest a potential anaerobic enzymatic mechanism.