phase Behavior of Chlorinated Solvent + Water + Alcohol Mixtures with Application to Alcohol Flushing

摘要

Alcohol flushing is a new in-situ remediation technique for the removal of water-immiscible solvnets from contaminated soil and groundwater. Understanding the changes in the physical and chemical properties of chlorinated solvents and the aqueous-phase solution during flushing is prerequisite for the successful application of this technology. The overall objectives of these experiments were to characterize the ternary-phase behavior, interfacial tension, viscosity, and density for mixtures containing a chlorinated solvent, water and alcohol. Two chlorinated solvnets were used: tetrachloroethylene and trichloroethylene. The alcohols studied included methanol, ethanol, and propan-2-ol. Results showed that the single-phase region of the ternary relationships increased as the molecular weight of the alcohol increased. The interfacial tension betweenthe chlorinated solvents and aqueous solutions decreased with increasing alcohol concetration and increasing molecular weight of the alcohol. Changes in the viscosity of water + alcohol mixtures due to the addition of the solvents were only evident at high alcohol concentrations. Small changes in density were noted for the chlorinated solvnets in equilibrium with water + alcohol solutions except in the case of trichloroethylene and propan-2-ol solutions, which exhibited considerable swelling.