DOWFAX surfactant components for enhancing contaminant solubilization

Surfactant selection is critical to successful implementation of surfactant -enhanced subsurface remediation. Previous research demonstrated the favora ble characteristics of commercial grade DOWFAX surfactants for enhancing co ntaminant solubilization. In this research we studied the effectiveness of higher purity DOWFAX components for enhancing containment solubilization. T he DOWFAX surfactant components are mono- and di-alkylated diphenyloxide di sulfonates and mono and di-sulfonated alkyl diphenyloxides. Surfactant solu bilization of phenanthrene increased as the surfactant hydrophobicity incre ased (increasing alkyl chain length and with dialkylation for a given chain length) and as the surfactant hydrophilicity decreased (mono- versus di-su lfonate). Surfactant sorption likewise increased with increasing surfactant hydrophobicity and for monosulfonates versus disulfonates. Surfactant sorp tion was reduced by a factor of 2.5 for the higher purity C-16 MADS compone nt versus commercial grade DOWFAX 8390 (which is a mixture of C16-MADS and DADS). in soil-contaminant systems surfactant-enhanced solubilization was o bserved to increase dramatically for DOWFAX components with higher solubili zation potential and was not significantly impacted by surfactant-media sor ption (reflecting the low sorption potential of these surfactants). These r esults thus further our understanding of how the DOWFAX components, and mix tures thereof impact surfactant-enhanced soil remediation. (C) 2000 Elsevie r Science Ltd. All rights reserved.