SORPTION AND TRANSPORT KINETICS OF A NONIONIC SURFACTANT THROUGH AN AQUIFER SEDIMENT

Sorption of nonionic surfactant onto aquifer sediment affects both surfactant transport and related surfactant solubilization properties as well as the potential for surfactant-aided mobilization of organic compounds in sediment-aqueous systems. Column experiments were conducted to evaluate the transport and sorption of a nonionic surfactant, Triton X-100, onto an aquifer sediment material, Lincoln fine sand. Unusual two-step breakthrough curves were observed in the column tests, suggesting the existence of two sorption regimes dependent on the sorbed surfactant concentration and molecular conformation. Elution of the sorbed surfactant exhibited considerable tailing. A simplified two-stage, sorption kinetic model is proposed as a first approximation toward characterizing the sorption phenomena, where sorption in each stage is governed by a specific kinetic parameter. The results from this study indicate the importance of kinetic phenomena to describe surfactant transport in sediments.