Dissolution kinetics of NAPLs at residual saturation: An investigation with coal tar
- Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Civil Engineering
Organic, nonaqueous phase liquids (NAPLs), trapped in the subsurface due to capillary forces, are often reported as sources of groundwater contamination. The dissolution of these liquids, has therefore been the subject of much research in recent years. In various experimental studies, local equilibrium between the flowing phase and the residual phase has been observed, but this is probably true only for a limited range of porous media, flow conditions, and NAPL saturations. This paper reviews current research efforts to quantify the kinetics of dissolution of residual fluids. Since the distribution of NAPL in a porous medium is complex, the common approach is to develop a correlation between the observed mass transfer coefficient and one or more experimental conditions. An experimental study was performed at Carnegie Mellon with coal tar as a contaminant at residual saturation in short, glass-bead-packed columns. The dissolution of coal tar into flowing solutions of organic solvent and water was studied as part of an effort to evaluate the feasibility of remediation of coal tar sites by injection of water-miscible organic solvents. The effluent coal tar concentrations from the columns was significantly below that predicted by local equilibrium. A correlation for mass transfer with the NAPL saturation and flow velocity was developed to describe the dissolution process. This correlation was then used to simulate the proposed solvent extraction process on a larger scale. The results showed that the effects of mass transfer limitations was more pronounced under certain conditions (such as low saturation) and less pronounced under other conditions (high saturation, greater contact length).
- OSTI ID:
- 5819041
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COAL TAR
DISSOLUTION
GROUND WATER
LAND RECLAMATION
ORGANIC SOLVENTS
PLANNING
REACTION KINETICS
SATURATION
SOILS
SOLVENT EXTRACTION
SOLVENT PROPERTIES
WATER
WATER POLLUTION
EXTRACTION
HYDROGEN COMPOUNDS
KINETICS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
SEPARATION PROCESSES
SOLVENTS
TAR
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