Attenuating organic contaminant mobility by soil modification

Abstract

Low organic matter clays, soils and aquifer materials have very little sorptive capability for common groundwater contaminants. Here we use organic cations of the form [(CH₃)₃NR]⁺ to displace naturally occurring exchange ions resulting in significantly higher organic matter contents, and greatly enhanced sorptive properties for nonionic organic solutes. The organic phase derived from exchanged hexadecyltrimethylammonium, where R is a C-16 hydrocarbon, behaved as a powerful partitioning medium that was 10 to 30 times more effective on a unit weight basis than natural soil organic matter for removing benzene, dichlorobenzene and perchloroethene from water. This simple soil modification might be used to improve the retardation capabilities of low organic matter soils and aquifer materials, and to enhance the containment capabilities of clay landfill liners and bentonite slurry walls.