Pesticide Partitioning within a Surfactant-Aided Soil Washing System

The most commonly used technique to remediate pesticide contaminated soil is soil washing technique; however, its cleaning efficiency is limited due to pesticide’s low water solubility and high sorption onto soil particles. In recent years, surfactants have been added into this process to help improve its contaminant removal efficiency. In this research, the sorption and desorption of pesticides (Atrazine and Diuron) onto/from five soil samples in the presence of surfactants (LAS [Linear Alkyl Sulfate]; SDS [Sodium Dodecyl Sulfate]; BC [Benzalkonium Chloride], and Triton-100) were investigated using batch equilibrium technique. Our results show that the presence of the surfactant has a significant effect on the pesticide partitioning within the soil washing system. The sorption of the surfactants have similar patterns but to a different extent. LAS and SDS sorb less and BC sorbs more onto the soils than Triton. At low surfactant concentration, instead of increasing the pesticide desorption, the sorption of the surfactants actually increases the sorption of the pesticides and the enhanced desorption happens only if the surfactant concentration is higher than a certain value which is surfactant and soil dependent. Moreover, different surfactants have different potential to enhance pesticide desorption and this enhancement is surfactant and soil dependent as well.