Surfactant solubilization of hydrophobic compounds in soil and water : I. Dodecylsulphate monomer and micellar partition coefficients for 28 polychlorinated biphenyls (PCBs) [41].

Reductions in the apparent soil-water partition coefficients (Kd (*)) for 28 polychlorinated biphenyls (PCBs) caused by the surfactant sodium dodecylsulphate (SDS) in the aqueous phase were studied. Above the critical micelle concentration (CMC) of the surfactant, Kd (*) was reduced by 2-3 orders of magnitude, but even far below CMC at environmentally relevant surfactant concentrations significant reductions in Kd (*) were observed. The plot of the soil-water partition coefficient (Kd) divided by Kd (*) versus the concentration of SDS allowed for the calculation of monomer (Kmn (oc)) and micellar (Kmc (oc)) surfactant-water partition coefficients normalized to organic carbon for each PCB congener. Kmn (oc) values were comparable with published values for the partition of PCBs between natural dissolved organic matter and lake water. Kmc (oc) values were up to 30 times higher than Kmn (oc) values and comparable with published octanol-water distribution coefficients. The findings of the present study underline the potential of surfactants at concentrations below their CMC to mobilize otherwise strongly bound hydrophobic compounds in soil-water systems.