Effect of Enhanced-Solubilization Agents on Dissolution and Mass Flux from Uniformly Distributed Immiscible Liquid Trichloroethene (TCE) in Homogeneous Porous Media

摘要

The use of enhanced-flushing technologies has emerged as a promising technique for the remediation of sites contaminated with immiscible liquids. An important aspect for the effective remediation of these sites depends on the physical heterogeneity of the subsurface and the related distribution of immiscible liquid present within porous media. Recent interest has developed in using mass flux-based approaches to evaluate remediation success and performance for immiscible liquid-contaminated sites. The unique focus of these experiments was to evaluate trichloroethene (TCE) mass flux behavior and mass removal effectiveness for various solubili-zation agents when the distribution of immiscible liquid is uniform. In order to accurately compare the performance of each enhanced-solubilization agent, the distribution of immiscible liquid must be consistent and uniform. Previous dissolution experiments have typically relied upon injecting immiscible liquid into the porous media which can result in nonuniform immiscible liquid distribution causing nonideal dissolution and mass flux behavior (i.e., immiscible liquid fingering and bypass flow). Homogeneous 20/30rnquartz sand was thoroughly mixed with a predetermined amount of immiscible liquid TCE and packed into columns to ensure that uniform distributions of residually saturated TCE (S_N=8-11%) were created. These columns were then flushed with a specific enhanced-solubilization flushing agent to initiate dissolution. Of the four enhanced-solubilization used, the lower solubilization power flushing agents (i.e., cyclodextrins) resulted in more ideal TCE mass flux behavior in which mass flux is maximized and maintained during the majority of the flushing experiment. A strong positive correlation (R~2=0.92) exists between enhancement factor and mass flux ideality which may suggest that these systems were in fact uniformly distributed with immiscible liquid. In order to appropriately evaluate and compare the effectiveness of specific solubilization agents, it is important to consider mass flux behavior in conjunction with elution behavior and mass removal efficiency.