Dissolution of Trichloroethene (TCE) from a Simple Multi-Component NAPL System
Abstract
The presence of complex NAPL mixtures in the subsurface further complicates remediation efforts, transport predictions, and the development of accurate risk assessments. A series of column and time sequential batch experiments were conducted to assess the factors controlling dissolution processes under dynamic flow and equilibrium conditions. TCE dissolution in the two-component NAPL systems (TCE and HEX) exhibited less rate limitations than the single-component TCE systems, likely due to the presence of a constant interfacial area for mass-transfer to occur during flushing. The multi-component TCE:HEX column system experienced the fastest mass removal time, but was not considered the most efficient in terms of mass-flux reduction. The batch experiments demonstrated that as mole fraction of a particular component of a NAPL (TCE) mixture decreases, greater dissolution nonideality occurs, resulting in greater observed concentrations than those predicted by equilibrium dissolution (i.e. Raoult's Law). Dissolution nonideality, quantified by the NAPL-activity coefficient, increased for the lower TCE mole fraction systems from 1.7 to 6.1 for TCE:HEX mole fractions of 0.2:0.8 to 0.003:0.997, respectively. The results of the batch experiments also indicated that dissolution mass-transfer rates were nearly identical for both the single-component TCE systems and the TCE:HEX systems. This suggests that intra-NAPL diffusion was not a rate-limited process under the conditions of these experiments.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.H41M..07B
- Keywords:
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- 1829 HYDROLOGY / Groundwater hydrology;
- 1831 HYDROLOGY / Groundwater quality;
- 1832 HYDROLOGY / Groundwater transport