T8 PM Measurement/ Estimation of Environmentally Relevant Physico-Chemical Properties
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 337-338

(ARE-1118-178860) Estimating partition coefficients for fuel-water mixture systems.

Arey, Jeremy¹, Gschwend, Philip², ¹ Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States² Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA

ABSTRACT- In many environmental transport problems, organic solutes partition between two immiscible phases that are each liquid mixtures. Examples include solute partitioning from gasoline, diesel fuel, and similar mixtures into contacting aqueous mixtures. To estimate the corresponding partition coefficients, we utilized linear solvation energy relationships (LSERs) developed for pure liquid-liquid systems, and we extended these to handle mixtures using either linear solvent strength theory or the solvent compartment model. These methods allowed prediction of liquid-liquid partition coefficients in a variety of fuel-water systems for a chemically diverse set of dilute solutes. When applied to 37 polar and nonpolar solutes partitioning between an aqueous mixture and several fuel-like mixtures (many including oxygenates), the root-mean-squared errors were a factor of 2 to 3 in the partition coefficient using these approaches. This was considerably more accurate than application of Raoult's law for the same set of systems. Regulators and scientists can use these methods to estimate fuel-water partition coefficients of novel additives in future fuel formulations and thus provide key inputs for "pre-manufacture" environmental assessments of these compounds.

Key words: fuel, LSER, oxygenate, partition-coefficient