Surfactant-enhanced mobilization of hydrocarbons from soil: Comparison between anionic and nonionic surfactants in terms of remediation efficiency and residual phytotoxicity

The aim of the present study was to assess the effectiveness of two surfactants (Polysorbate 80 – Tween 80 and Sodium Dodecyl Benzensulphonate – SDBS) for the remediation of hydrocarbon-contaminated soil. To study the effectiveness of these surfactants, an experimental laboratory-scale apparatus was set up for the simulation of a soil flushing intervention. Different surfactant concentrations and flushing flow rates were investigated. At the end of the experiments, the removal efficiency was evaluated and phytotoxicity tests were performed by means of germination index (GI). Results showed that the use of both surfactants allows to reach high removal efficiency (~50% for Tween 80 and ~70% for SDBS) of hydrocarbons from soil and that either the surfactant concentration and the contact time between surfactant and contaminant affected the extraction performance. GI results showed different effects of the two surfactants on the phytotoxic features of the soil after treatment. Indeed, while the soil treated with SDBS was found to be more phytotoxic, leading to a lowering of the GI (10.88 %), the soil samples flushed with Tween 80 were characterized by higher values (146.61%). These results might be of interest in the case of surfactant application in remediation interventions in soils intended for future agricultural activity.