The influence of interfacial properties on two-phase liquid flow of organic contaminants in groundwater

Abstract

The purpose of this project is to investigate how changes in interfacial chemical properties affect two-phase transport relationships. Specifically, the objective is to develop a quantitative theory that will enable the prediction of changes in the capillary pressure-saturation relationship, a fundamental constitutive relationship in multiphase flow modeling, from changes in interfacial properties through a knowledge of their effect on wettability. The information presented here summarizes the progress we have made in the first project period. Based on preliminary adsorption, surface charge and surface potential measurements, we have demonstrated that it is possible to change the wettability of silica in a controlled manner by adsorbing varying quantities of a strongly-binding, cationic surfactant like cetyltrimethylammonium bromide (CTAB). Adsorption, surface charge and surface potential measurements have been made on the silica-water-CTAB system to yield a relationship between the amount adsorbed and the interfacial potential. Our work on the ideal soil model has demonstrated that the incorporation of roughness effects in the ideal soil model improves the prediction of the operative contact angles for drainage and imbibition from the intrinsic contact angle. This leads to better estimates of the capillary pressure-saturation relationships. Preliminary capillary pressure experiments on the silica-water-air system have shown that adsorptionmore » of a surfactant at the solid surface changes the capillary pressure-saturation relationship significantly.« less