| Surfactants are widely used in household, industrial and agricultural applications. Adsorption of surfactants at the gas-liquid interface reduces the surface tension of water, altering water retention and hydraulic conductivity functions of unsaturated soils. In addition, surfactants have emerged as a potential means to enhance the removal and bioavailability of HOCs in soil and sediment environments. In this work, experimental studies and mathematical modeling were performed to investigate the effects of surfactants on water retention and flow in unsaturated soils, as well as, the fate and transport of hexachlorobenzene (HCB). Soil-water retention characteristics were determined at different surfactant concentrations using Tempe cells for a reference F-70 Ottawa sand and Appling soil. One-dimensional unsaturated column experiments were conducted to study the effect of surfactants on solute transport and water flow. Batch and water saturated column experiments were performed to investigate the fate and transport of two representative nonionic surfactants: Triton X-100 and Tween 80. Batch and column experiments were conducted to determine rate-limited coupled sorption and transport of HCB in the presence of Tween 80. |
