Effects of Surfactants on Solubilization of Perchloroethylene (PCE) and Trichloroethylene (TCE)

Abstract

Enhanced solubilization of dense nonaqueous phase liquids (DNAPLs) especially chlorinated hydrocarbons using four types of surfactants was investigated. The solubilization kinetics of perchloroethylene PCE (100 mg/L solubility in water) and trichloroethylene TCE (1000 mg/L) in anionic (sodium dodecyl sulfate (SDS)), nonionic (Triton X-100), cationic (cetyltrimethylammonium bromide (CTAB)), and a biosurfactant (UH biosurfactant) were investigated at room temperature in continuously stirred batch reactors. The size distribution of surfactant micelles were measured using the dynamic light scattering device (DLS). The mean size of SDS, CTAB, Triton X-100, and UH biosurfactant micelles were 4.2 nm, 3.8 nm, 4.5 nm, and 59.1 nm, respectively. Micelle partition coefficients (Km) and molar solubility ratio (MSR) for PCE and TCE in 10 g/L of surfactant solutions have been quantified, and the solubility of PCE and TCE in the surfactant solutions increased by about 10-fold. Solubilization kinetics for PCE and TCE in various surfactant solutions was represented using a hyperbolic relationship. Also the relationship between solubility and interfacial surface tension reduction was investigated. Of the surfactants studied, Triton X-100 had the highest PCE solubilized per gram of surfactant, whereas for TCE, biosurfactant had the highest TCE solubility per gram of surfactant.