Feasibility study of surfactant use for remediation of organic and metal contaminated soils

In this investigation, four surfactants were examined in a laboratory study that included testing for naphthalene solubilization capacity, surfactant sorption to soil, and treatability for a sandy soil artificially contaminated with lead and naphthalene. Of interest was an examination of surfactant performance characteristics under the acidic conditions that may be required for metal removal. Although pH is recognized as a critical factor in metal sorption to soils, it did not significantly impact the solubilization ability of any of the surfactants for naphthalene. The sorption of nonionic surfactants to the soil was not affected by pH, while sorption of anionic surfactants increased as the pH decreased. Although nonionic surfactants showed better solubility enhancement for naphthalene than anionic surfactants, the latter may enhance lead desorption from the soil, presumably due to interactions between the anionic head groups of the surfactant and the Pb²⁺ ion. A mass balance model was used to interpret experimental data for naphthalene solubilization. The results of the study suggest that remediation of metal-organic contaminated soils by an acidic solution (for metal removal) containing surfactants (for organic removal) may be feasible.