Abstract
At hazardous waste sites, removal of contaminant nonaqueous phase liquids (NAPLs) by mobilization using surfactant and cosolvent flushing is an attractive remediation option. Study of the changes in NAPL saturations (S n ) and specific NAPL-water interfacial areas (a nw ) before, during, and after the remediation process is essential in the characterization of waste sites, design, and evaluation of remediation strategies and risk assessment. Empirical indices, such as the capillary number (N Ca ) and, recently, the total trapping number (N T ), were presented in the literature to describe mobilization. Methods available for the measurement of S n allowed an adequate characterization and modeling of the S n -N Ca relationship. In contrast, no methods were available to measure a nw , and hence, no attempts to estimate or model the a nw -N Ca were reported. In the current work, the a nw -N T relationship was experimentally evaluated, using the recently reported interfacial tracers (IFTr) technique to estimate a nw and surfactant-flushing as a means of mobilization. It was found that, following mobilization of residual decane using AOT-100 surfactant, a nw initially remained insensitive to increase in N T , decreased passing through a minimum, and finally increased a with further increase in N T . This final increase is possible due to droplet dispersion or emulsification. A simple analytical model to describe the same relationship also is presented. The methods and results presented can be used as a basis for future investigations of changes in a nw following chemical flooding.
Published Version
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