Ionic diffusion phenomena and organic polymer addition in thin clay films: Investigation of electrokinetic remediation and heavy metal transport mechanisms in clay and the construction of a miniaturized total analysis system.

摘要

This research work addresses two fundamental issues involving molecular transport phenomena in clay minerals. The majority (Part II) of this dissertation describes studies of ionic diffusion through thin layer clay films and the effect of a range of organic polymer additions on that diffusion. The final section (Part III) of this dissertation describes the development of a miniaturized electrokinetic remediation analysis cell and the investigation of ionic heavy metal transport mechanisms and subsurface remediation methodology. Both research projects contribute to the fundamental understanding of ionic material transport in soils.; The movement (diffusive transport) of molecules through clay barriers used as landfill liners at municipal and other waste disposal sites has been implicated in pollution of ground waters. When hazardous materials migrate into the ground water tables they can pose serious health risks to human and animal populations. The flow of ions through nanoporous media is also of great significance in the fields of agriculture, industrial chemistry, oil technology and environmental chemistry. The importance of clay-organic interactions in industrial practices and the possibility of producing materials with new or modified properties have attracted considerable attention to this field.; A rapid determination (under 12 hours) of diffusion rates has been obtained by use of a unique fiber optic instrument based on absorption spectrometry. The system allows for a true sink-source experimental arrangement. This dissertation describes the validation of that fiber optic detection system for measuring diffusive transport of solutes in clays. The detection limit can be as low as parts per million for molecules with molar absorptivities larger than 10 4 in the LTV-visible range. Additionally, the effect that organic polymer additions have on diffusion phenomena and the reasons for that effect are described. A mathematical model and computer simulation of the system was also developed. The experimental data are well simulated by the computer model and compared to that from an electrochemical system.