MINIMIZING SURFACTANT LOSSES USING TWIN-HEAD ANIONIC SURFACTANTS IN SUBSURFACE REMEDIATION

The economics of surfactant-enhanced subsurface remediation are affected by losses of surfactants due to such phenomena as precipitation, sorption, etc. It is hypothesized that surfactants with twin head groups will exhibit lower losses in the subsurface as compared to single head group surfactants while maintaining high solubilization. The contaminant addressed in this research was naphthalene, and the surfactants evaluated were mono- and disulfonated anionics (sodium dodecylbenzenesulfonate and alkyl diphenyl oxide disulfonates). The results of this research demonstrated that disulfonates were significantly less susceptible to precipitation than monosulfonates and that disulfonates were less susceptible to sorption than monosulfonates and also less prone to sorption than nonionic surfactants evaluated in other research. Disulfonates also exhibited greater solubilization of naphthalene than monosulfonates and slightly lower solubilization than nonionics. Solubility ratios were evaluated on both a molar (MSR) and weight (WSR) basis, and corresponding micelle-phase/aqueous-phase partition coefficients (K(m) and K(w)) were reported. This research demonstrated that disulfonate surfactants are less susceptible to losses than other surfactants evaluated and thus are strong candidates for use in surfactant-enhanced subsurface remediation.