| The effectiveness of microemulsions in aquifer remediation depends on both the surfactant's interactions with the nonaqueous phase liquid (NAPL) and with the aquifer media. Knowledge of the effects of alcohols, which are an indispensable ingredient to microemulsions, on these interactions is essential for the optimum microemulsion formulation.;The partitioning behavior of alcohols in Winsor Type I microemulsions was investigated using the pseudophase model coupled with the alcohol self-association model. A linear relationship was found between interfacial cosurfactant concentration and NAPL solubilization. A two-region partitioning model for alcohol in the micelle was proposed. Alcohol prefers to partition into the micelle interface, acting as a cosurfactant before interfacial alcohol saturation, and it prefers to partition into the micelle inner core, acting as a polar oil after interfacial alcohol saturation.;Based on the alcohol partitioning behavior, NAPL solubilization and phase behavior, I found that medium-chain alcohol is a good cosurfactant for solubilizing light nonaqueous phase liquid (LNAPL), while branched short-chain alcohol is a good interfacial modifier for solubilizing dense nonaqueous phase liquid (DNAPL).;Relatively high perchlorethylene (PCE) solubilization and high interfacial tension (IFT) were simultaneously achieved by using a nonionic surfactant/cosurfactant system. Experimental data suggest that remediation of aquifers, contaminated with DNAPL, can be achieved via in-situ solubilization, without mobilization.;Precipitation is the primary mechanism for anionic surfactant loss in calcareous soils, while adsorption is the predominant loss mechanism in soils with high iron oxide content. Cosurfactant decreases anionic surfactant precipitation and adsorption through comicellization. |
