Enhanced solubility in nanopores and its role in adsorption separations

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Proposal Number: 1603851, GubbinsEnhanced solubility in nanoporous media and its role in adsorption separationsWhen gases or liquids are adsorbed into porous materials, such as activated carbon and silica, the fluid confined within the narrow pores often displays properties that are very different from those in the bulk gas or liquid. These differences are exploited in many practical applications, including industrial separation of chemicals, and in daily life in the purification of water and air. Much research has been reported on the effects of such confinement in a nanoporous solid on vapor-liquid and liquid-solid phase separations for pure substances, and the effects are found to be large. However, little is known of the effects of such confinement on the solubility of sparingly soluble solutes in liquid solvents. Knowledge of these confinement effects on solubility are important in many applications, including industrial adsorption separations, oil and gas exploration, hydraulic fracturing, geological carbon dioxide sequestration, the behavior of toxic gases and chemicals in soils, dissolved gases in fuel cells and in drug delivery. In this project molecular simulation and modeling will be used to investigate the effects of confinement within porous materials on the solubility of sparingly soluble substances in water and in liquid hydrocarbons. An important aspect will be the development and testing of molecular theory for solvents that exhibit strong molecular association or Coulombic interactions; this will be of particular significance for water and aqueous electrolytes. The initial work will involve a broad study for simple systems in which the pores are of simple geometry and fluid molecules are non-polar, that will provide a fundamental understanding of the influence of the materials and other variables on the solubility. This will be carried out using advanced molecular simulation methods (Monte Carlo and molecular dynamics), and will explore effects of temperature, pressure, chemical composition, pore size and shape. In addition a density functional theory will be developed for highly polar and associating molecules for the first time. This latter part of the work will be carried out in collaboration with researchers at the East China University of Science and Technology in Shanghai. In addition, further and more detailed studies will be made for specific systems of direct interest in industrial adsorption separations, enhanced oil and gas recovery and carbon dioxide sequestration. While the research under the grant will be primarily theoretical (molecular simulation and classical density functional theory studies), the team will also collaborate with three international research groups in the U.K., Poland and Germany, carrying out experiments in this area. The development of density functional theory for water and aqueous solutions is expected to impact many fields. One graduate student and one undergraduate will be involved in this research, and will receive training in advanced simulation and theory methods, and gain experience of international research collaboration.