Evaluation of an elevated non-ionic surfactant critical micelle concentration in a soil/aqueous system

In this study, an elevated non-ionic surfactant critical micelle concentration (CMC) in a soil/aqueous system was examined. Experimental measurements have been made of surfactant solubilization of polycyclic aromatic hydrocarbons (PAH) (i.e. fluoranthene and pyrene) in a 5-month aged PAH contaminated soil, as well as surfactant sorption onto soil. Fluoranthene and pyrene in the soil/aqueous system in the presence of three non-ionic surfactants (i.e. Tween 80, Triton X-100 and Brij 35) were extracted using dichloramethane and analyzed using GC-MS. Maximum sorption of non-ionic surfactant onto soil was evaluated using a surface tension technique. It was observed that PAH solubilization is proportional to surfactant dose after the elevated CMC, termed as the effective CMC (CMC eff), is achieved. The values of surfactant CMC eff assessed by the surface tension technique were found to be similar to those determined from surfactant PAH solublization, thereby proving the research hypothesis that surfactant sorption is the cause for the elevation of surfactant CMC in a soil/aqueous system.