Accurate selection of a surfactant/alcohol formulation for mobilization of organic contaminants from soils requires consideration of oil volume fraction (θ O ) as a major parameter. This study examines the influence of θ O on behavior of systems containing brine, sodium dodecyl benzenesulfonate, n-pentanol, and n-alkanes. A batch salinity scan technique was employed to investigate the change of systems with the change of θ O . The results reveal that the effect of θ O is significant; with increasing θ O , the systems change from Winsor II → Winsor III → Winsor I. The batch experimental data were then used to develop a correlation for optimum formulation with corrected term, e.g. f(A) alcohol function to take into account the effect of θ O . At constant concentration of n-pentanol, the correlation exhibits a linear dependence of logarithm of optimal salinity (S*) on θ O . The importance of considering θ O as a major parameter in the optimum correlation was verified through the column experiments and good agreement was obtained. A surfactant formulation selected based on the developed correlation for θ O equal to degree of oil saturation (SO ) possessed the highest potential for n-dodecane recovery among other formulations. These findings will be valuable in the design of groundwater remediation scenarios when surfactant and alcohol are used for remediation of crude oils.

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Gypsum is widely used for the manufacture of various building materials because of its advantages such as rapid setting, good thermal insulating property and fire resistance, but their use is limited to interior finishings because of its poor water resistance. This paper deals with an improvement in the water resistance of gypsum composites by polymer modification and partial replacement of gypsum with ground granulated blast-furnace slag, silica fume and ordinary Portland cement. Polymer-modified gypsum-based composites are prepared with various polymer-binder (a mixture of gypsum and mineral admixtures) ratios, and tested for water absorption, flexural and compressive strengths before and after water immersion. In addition, the long-term water resistance of the polymer-modified gypsum-based composites with a superplasticizer are investigated by 3-y water immersion. As a result, SBR modified gypsum-based composites with optimum mix proportions are developed from the viewpoint of water resistance and strength development. The high water resistance of the gypsum-based composites is achieved by polymer modification, superplasticizer addition, and partial replacement of gypsum with the mineral admixtures.