Solubilization and adsolubilization of phenylethanol and ethylcyclohexane using anionic carboxylate extended surfactants on an aluminum oxide surface

Abstract

Surfactant enhanced aquifer remediation (SEAR) of organic contaminants has been receiving increased attention. It makes use of extended surfactants, within which groups of intermediate polarity such as polypropylene oxides (PO) and/or ethylene oxide (EO) have been inserted between the hydrocarbon tail and hydrophilic head groups, thereby enhancing the surfactants’ solubilization capacity. In this study, the adsorption/desorption, solubilization, and adsolubilization capabilities of anionic extended surfactants are evaluated and compared to those of a conventional surfactant (C12S). The results of surfactant adsorption onto aluminum oxide surfaces showed that the sulfate extended surfactant (C16.5-4POS) has the highest maximum adsorption capacity. Moreover, the carboxylate extended surfactants (C16.5-4PO5EOC and C17-4PO5EOC) have strong packing (bilayer coverage) and reduce the surfactants’ desorption from the surface. For solubilization and adsolubilization, the extended surfactant systems showed greater phenylethanol and ethylcyclohexane solubilization and adsolubilization compared to the C12S. This is because the extended surfactants have larger aggregation numbers than that of the C12S. These results provide insights into extended surfactant-based admicellar systems that can enhance the industrial and environmental applications of surfactant-modified materials.