Kinetic Study of MTBE Removal from Water by Stripping Method

Methyl tertiary-butyl ether (MTBE) is a gasoline additive used to enhance gasoline octane. It is highly soluble in water and is known for its carcinogenicity; hence its high risk of groundwater contamination. The present study was mainly designed to investigate MTBE effect on gasoline solubility in water, determine the associated COD value, and identify the kinetics of MTBE elimination from water by the stripping method. The results show that the kinetics of MTBE elimination from water can be expressed by a first order equation with the rate constants obtained as 0.0055 min-1 and 0.0074 min-1 at the two stirring rates of 100 rpm and 250 rpm, respectively. These rate constants are evidently high and are indicative of the effectiveness of the stripping method in MTBE removal from water. A linear function was established between COD reduction with respect to time at room temperature at low stirring rates (100 rpm) but an exponential function at high stiring rates (250 rpm). The solubility of gasoline with different additives (MTBE, ethanol, methanol) in water was also investigated. The results revealed that gasoline solubility decreased from 90 mg/l to 80mg/l and 69 mg/l, respectively, in the presence of ethanol and methanol. This is while the solubility of MTBE-containing gasoline in water rose from 90 mg/l to 778 mg/l, which shows an 8-fold increase in solubility in water.