title: Implications of alcohol partitioning behavior for in situ density modification of entrapped dense nonaqueous phase liquids.
abstract: Surfactant-based remediation techniques have the potential to be very effective for removing dense nonaqueous-phase liquids (DNAPLs) from contaminated sites. However, a risk associated with surfactant-based remediation of DNAPLs is the potential for unwanted downward mobilization of the DNAPL contaminants, making them more difficult to remove from the subsurface. The work described here examines the use of hydrophobic alcohol solutions to reduce the densities of entrapped DNAPLs, converting them to light nonaqueous-phase liquids (LNAPLs). Results of partitioning studies are presented for alcohol-DNAPL systems, in the absence and presence of surfactants. Results indicate that alcohol concentrations near saturation are necessary for conversion of DNAPLs to LNAPLs--particularly for high-density DNAPLs such as trichloroethylene (TCE) and tetrachloroethylene (PCE). Although surfactants can increase the mass of alcohol that can be delivered to a contaminated zone, they appear to change the partitioning equilibrium such that higher alcohol concentrations are required to achieve the same result. Results of this work indicate the importance of minimizing dilution during density modification applications and suggest the concept of using an alcohol macroemulsion flood for density conversion. Implications of the results of this work for remediation system design are discussed.
authors.affiliation: School of Civil Engineering and Environmental Science, University of Oklahoma, Norman 73019-1024, USA. kibbey@ou.edu
authors.forename: Tohren C G
authors.initials: TC
authors.lastname: Kibbey
authors.forename: C Andrew
authors.initials: CA
authors.lastname: Ramsburg
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Pennell
authors.forename: Kim F
authors.initials: KF
authors.lastname: Hayes
mesh_terms: D004784:Environmental Monitoring; D004787:Environmental Pollution / Q000517:prevention & control; D000431:Ethanol / Q000032:analysis / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D012997:Solvents / Q000032:analysis / Q000737:chemistry*; D013750:Tetrachloroethylene / Q000032:analysis / Q000737:chemistry*; D014241:Trichloroethylene / Q000032:analysis / Q000737:chemistry*; D014872:Water Movements
chemical_list: D012989:Soil Pollutants; D012997:Solvents; D014241:Trichloroethylene; D000431:Ethanol; D013750:Tetrachloroethylene