Biosurfactant microfoam: Application in the removal of pollutants from soil

Surfactant solutions are frequently used in environmental decontamination. More recently, the use of microfoams (MF) has been investigated as an alternative to the use of surfactant solutions, since MF have the advantage of improving the contact with the contaminated environment due to their surface properties. The aim of this study was to remove petroleum and diesel oil from soil using microfoams of biological and chemical surfactants and to compare their efficiencies in removing the contaminants. For this purpose, a sandy soil contaminated with 5% (w/w) of petroleum and 5% (w/w) of diesel oil was used. After 72 h, the soil samples were washed with solution or microfoam of two chemical surfactants (sodium dodecyl sulfate – SDS and cetyltrimethylammonium bromide – CTAB) and one biosurfactant (rhamnolipid – RML). At the end of the remediation process using SDS or RML microfoams, petroleum removal efficiencies of 44.26 ± 0.54% and 42.12 ± 0.61% were obtained, respectively; for the soil contaminated with diesel oil, the removal efficiency using MF of SDS and RML was 62.90 ± 0.68% and 44.75 ± 1.22%, respectively. For both contaminants, either CTAB solution or MF had low removal efficiency. Probable mechanisms involved in the remediation process were solubilization for petroleum and mobilization for diesel oil.