Entrapped and pooled dense nonaqueous-phase liquids (DNAPLs) often persist in aquifers and serve as a long-term source of groundwater contamination. To address the problematic nature of DNAPL remediation, a surfactant-enhanced aquifer remediation (SEAR) technology, @entity9680 ( @entity9680 ), has been developed which significantly reduces the risk of downward migration of displaced DNAPLs. The @entity9680 method is designed to accomplish DNAPL density conversion through the introduction of a partitioning @entity167 , @entity10439 ( @entity32361 ), in a predisplacement flood using conventional horizontal flushing schemes. Subsequent displacement and recovery of the resulting LNAPL is achieved by flushing with a low-interfacial tension surfactant solution. The objective of this study was to investigate density conversion of two representative DNAPLs, @entity30170 (CB) and @entity4965 ( @entity4966 ). A series of batch experiments was performed to assess changes in NAPL composition, density, and phase behavior as a function of @entity32361 mole fraction. Experimental results were used to develop contaminant/ @entity32361 /water ternary phase diagrams and to elucidate regions of contrasting NAPL density. UNIQUAC calculations are presented to support measured compositional and phase behavior data. Density conversion of CB and @entity4966 , relative to water, occurred at NAPL @entity32361 mole fractions of 0.38 and 0.50, respectively. Significant incorporation of water into the organic phase was observed at relatively high @entity32361 mole fractions and was shown to limit changes in NAPL composition and density. Interfacial tensions between CB-NAPL and @entity4966 -NAPL and a 6% (by wt) @entity32361 aqueous solution were found to decrease with increasing NAPL @entity32361 mole fraction, although in both cases the measured values remained above 2.5 dyn/cm. Total trapping number calculations suggest that, in most aquifer formations, density conversion can be achieved without premature NAPL displacement using a 6% (by wt) @entity32361 aqueous solution.

Density-modified displacement for dense nonaqueous-phase liquid source-zone remediation: density conversion using a partitioning XXXX .

@entity4966 :: ('CHEBI:16602', 'Chemical') :: ['TCE'] @entity30170 :: ('MESH:C031294', 'Chemical') :: ['chlorobenzene'] @entity167 :: ('CHEBI:16236', 'Chemical') :: ['alcohol'] @entity9680 :: ('MESH:D052456', 'Disease') :: ['density-modified displacement', 'DMD'] @entity32361 :: ('CHEBI:28885', 'Chemical') :: ['BuOH'] @entity10439 :: ('MESH:D020001', 'Chemical') :: ['n-butanol'] @entity4965 :: ('MESH:D014241', 'Chemical') :: ['trichloroethene']
@entity167 :: (CHEBI:16236,Chemical) :: ['alcohol']
