Solubility and sorption of petroleum hydrocarbons in waterand cosolvent systems
CHEN Hong , CHEN Shuo , QUAN Xie , ZHAO Yazhi , ZHAO Huimin
DOI:
Received November 01, 2007,Revised February 12, 2008, Accepted , Available online
Volume 20,2008,Pages 1177-1182
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The solubility and sorption of oil by uncontaminated clay loam and silt loam soils were studied from water and cosolvent/water
solutions using batch techniques. The data obtained from the dissolution and sorption experiments were used to evaluate the
applicability of the cosolvent theory to oil as a complex mixture. Aqueous solubility and soil-water distribution coe cients (Kd,w,
L/kg) were estimated by extrapolating from cosolvent data, with a log-linear cosolvency model, to the volume fraction of cosolvent
( fc) 0, and were compared with direct aqueous measurements. The extrapolated water solubility was 3.16 mg/L, in good agreement
with the directly measured value of 3.83 mg/L. Extrapolated values of Kd,w for the two soils were close to each other but consistently
higher than the values from direct aqueous measurements, because of the presence of dissolved organic carbon (DOC). The partition
coe cient (KDOC) between the DOC and the freely dissolved phase and the OC-normalized sorption coe cient (KOC) were determined.
The average values of logKDOC and logKOC were estimated as 4.34 and 3.32, respectively, giving insight into the possibility of oil
becoming mobilized and/or of the soil being remedied. This study revealed that the cosolvency model can be applied to a broader range
of hydrophobic organic chemicals (HOCs) than has been previously thought. The results aided in a reliable determination of water
solubility and sorption coe cients and provide information about the fate of oil in solvent-contaminated environment.
