Effect of Dibutyltin Dichloride on the Partitioning Behavior of Surfactant,n-Butanol, Perchloroethylene, and Water

Abstract

Organometallic compounds added to organic compounds are sometimes found in contaminated sites. An organometallic compound is considered a dense nonaqueous phase liquid (DNAPL); thus, applying conventional surfactant-enhanced aqueous-based remediation may not be effective. Consequently, density-modified displacement (DMD), which is a surfactant-based remediation approach that decreases the density contrast between the remedial solution and the mobilized nonaqueous phase liquid (NAPL) through butanol (BuOH) partitioning, has been introduced. This approach converts a DNAPL into a light NAPL (LNAPL). Partitioning of each component during DMD is a vital variable in achieving efficient remediation. This study aimed to determine the effect of dibutyltin dichloride (DBT) on the distribution of each component between the aqueous phase and NAPL during the treatment process. DBT behaved as a polar organic compound and increased the polarity of the NAPL. When compared to the experiment with perchloroethylene (PCE) alone, presence of DBT increased partitioning of BuOH and the anionic surfactant from the aqueous phase to the NAPL. Moreover, presence of the anionic surfactant in the NAPL combined with a negligible level of aqueous surfactant at equilibrium in the system appeared to increase the partitioning of BuOH into the NAPL. This study's finding can be applied to the DMD technique. It can be expected that, by adding a proper polar/ionic organic compound or surfactant, the aqueous BuOH can be adequately reduced, thereby easing the transformation of the DNAPL into an LNAPL at the turning point in the DMD process.