SOLUBILIZATION OF DODECANE, TETRACHLOROETHYLENE, AND 1,2-DICHLOROBENZENE IN MICELLAR SOLUTIONS OF ETHOXYLATED NONIONIC SURFACTANTS

Although surfactants have received considerable attention as a potenti al means for enhancing the recovery of organic compounds from the subs urface, only limited information is available regarding the micellar s olubilization of common groundwater contaminants by nonionic surfactan ts. The purpose of this study was to examine the influence of surfacta nt properties and environmental factors on the solubility of dodecane, tetrachloroethylene (PCE), and 1,2-dichlorobenzene (DCB) in micellar solutions of Witconol 2722, Tergitol NP-15, and Witconol SN-120. A mat rix of batch experiments was performed at 10 and 25 degrees C and in t he presence of CaCl2 for surfactant concentrations ranging from 0.5 to 15% by weight. Although the hydrophile-lipophile balance (HLB) values of the surfactants are similar, Witconol 2722 solubilized approximate ly three times more organic than the other surfactants, which was attr ibuted to the greater alkyl chain length and ethoxylation of Witconol 2722. Results of HLB scans, conducted using Tergitol NP surfactants, s howed that solubilization capacity was related to the micelle core vol ume and that cloud point effects can reduce the aqueous solubility of PCE. These findings demonstrate the importance of considering the spec ific surfactant-organic interactions, cloud point temperature, and mac roemulsion formation when selecting nonionic surfactants for use in su bsurface remediation applications.