| Abstract
| - Partitioning alcohol tracers were evaluated for characterizingthe hydrophobicity of high molecular weight light,nonaqueous phase liquids (LNAPLs). Alcohol partitioningcoefficients were found to decrease with increasing n-alkanemolecular size. It is hypothesized that this decrease inpartitioning coefficient is due to a decreased entropy ofmixing. A thermodynamic model and an empirical modelwere used for fitting alcohol partitioning coefficients forn-alkanes ranging from hexane to hexadecane. Theresulting expressions were further evaluated for characterizingequally and more hydrophobic oils of unknown equivalentalkane carbon number (EACN), including squalane(expected EACN of 24−30), and lower EACN oils (3.0−20),including PCE (EACN ∼ 3.0). Good agreement wasobserved for all the high EACN oils and for PCE. Theagreement becomes progressively poorer as the EACNdecreases below 3.0, illustrating the danger of extrapolatingwell beyond the range of data used to develop anempirical relationship. Based on our results we proposethat simultaneously using the thermodynamic and empiricalmodels can further characterize a NAPL based on asingle partitioning tracer test.
|
