Remediation and by-products of MTBE in groundwater by a photochemical process

Abstract

MTBE has been used as an octane number enhancer in gasoline, and blended with gasoline to about 15% by volume. High concentrations of MTBE have been discovered in the groundwater at a number of petrol stations in Iran. MTBE exhibits very high mobility in groundwater. Due to its solubility, groundwater contaminated with MTBE poses many problems for remediation. The properties of MTBE, including water solubility, vapour pressure, soil adsorption coefficient, retardation factor and Henrys law constant affect the selection and design of remediation technologies. Although MTBE is difficult to treat economically with conventional techniques, it readily degraded photocatalytically. The degradation of MTBE at high concentration (10,000 μg/l) was investigated in batch nanocrystalline TiO2 slurries. The optimum loading of TiO2 was found experimentally. In this experiment MTBE degradation proceeded with a pseudo first order reaction. The primary by-products have been identified. Mass balance calculation has shown that MTBE is completely mineralised. A reaction pathway is proposed.