Cosolvent effects of oxygenated fuels on PAH solubility

Cosolvents have been recognized to have a significant impact on the redistribution and movement of hydrophobic organic compounds (HOCs) in the environment. The cosolvent effect of oxygenated compounds (methanol, ethanol, and methyl tert-butyl ether) on the solubility of polynuclear aromatic hydrocarbons (PAHs) was examined by laboratory experiments. Coal-tar-contaminated sediment was used to study the redistribution and facilitated solubilization of 18 PAH compounds in both sediment and aqueous phases caused by cosolvent effects when oxygenated fuel spills occur. A batch dilution experiment was designed to represent the dilution effect of the cosolvent in a simulated river system. The results indicate that PAH solubility increased essentially in a log-linear manner with an increased volume fraction of methanol and ethanol. Deviations from a log-linear relationship were observed for methyl tert-butyl ether due to its limited aqueous solubility, and the cosolvent effect was seen only at the simulated fuel spill site. A linear relationship between the cosolvency power and logarithm of octanol/water partition coefficient was observed.