Surfactant-enhanced soil washing for  the remediation of sites contaminated with pesticides

Erick R. Bandala, Fernando Aguilar and Luis G. Torres

The application of surfactant-enhanced soil washing for the remediation of soil contaminated with a chlorinated pesticide was tested. The pesticide used, 2,4-dichlorophenoxyacetic acid (2,4-D), is one of the most widely applied in Mexico. The effectiveness of two different surfactants: sodium dodecyl sulphate (SDS) and ethoxylated lauryl ether (Brij 30), at removing 2,4-D from the soil was assessed. The effect of surfactant concentration, pH and ionic strength on the pesticide removal were also examined. It was found that the anionic surfactant (SDS) showed the best results, being capable of removing up to 50% of the pesticide using one soil-washing step, and up to 80% using two consecutive soil-washing steps; whereas the non-ionic surfactant (Brij 30) showed lower efficiency, removing only 13% of the pesticide from the soil under the most favourable conditions. Tests carried out at different pH values did not show any positive effect on the extraction process, but conversely, when the pH value was adjusted to lower or higher values than that of the original mixture, pesticide removal decreased considerably for both surfactants tested. The use of sodium chloride to modify the ionic strength of the extraction mixture was observed to improve the percentage extraction shown by Brij 30, whereas, in the case of SDS, no such effect was observed.

© EPP Publications Ltd 2010