Estimating Partition Coefficients for
Fuel−Water Systems: Developing
Linear Solvation Energy
Relationships Using Linear Solvent
Strength Theory To Handle Mixtures
posted on 2005-04-15, 00:00authored byJ. Samuel Arey, Philip M. Gschwend
In many environmental transport
problems, organic
solutes partition between immiscible phases that consist
of liquid mixtures. To estimate the corresponding partition
coefficients, we evaluated the efficacy of combining
linear solvation energy relationships (LSERs) developed
for pure 1:1 systems via application of linear solvent strength
theory. In this way, existing LSERs could be extended to
treat solute partitioning from gasoline, diesel fuel, and similar
mixtures into contacting aqueous mixtures. Unlike other
approaches, this method allowed prediction of liquid−liquid
partition coefficients in a variety of fuel−water systems
for a broad range of dilute solutes. When applied to 37 polar
and nonpolar solutes partitioning between an aqueous
mixture and 12 different fuel-like mixtures (many including
oxygenates), the root-mean-squared error was a factor
of ∼2.5 in the partition coefficient. This was considerably
more accurate than application of Raoult's law for the
same set of systems. Regulators and scientists could use
this method to estimate fuel−water partition coefficients
of novel additives in future fuel formulations and thereby
provide key inputs for environmental transport assessments
of these compounds.