| Recent advances in computationally efficient algorithms and accurate force field have opened the door for investigating molecular structure on a microscopic level. My research involves the use of Gibbs ensemble Monte Carlo simulations in con junction with the transferable potential for phase equilibria (TraPPE) force field to explore interesting separation phenomena such as tunable solvents, semi-fluorinated hydrocarbon surfactants, and reversed-phase liquid chromatography (RPLC) systems. Detailed microscopic pictures and analysis are particularly emphasized in the study.; The miscibility of hydrocarbon/perfluorocarbon mixtures can be tuned via pressurization with carbon dioxide. This unique behavior makes these mixtures strong candidates for biphasic catalytic processes, where the pressure tuning method allows switching from two liquid phases to one and vice versa thereby allowing for fast turnover and facile catalyst separation. The simulations focus on analyzing the microheterogeneous nature of the liquid phases through snapshots, radial distribution functions and local mole fraction enhancements.; The addition of semi-fluorinated hydrocarbon surfactants can greatly increase the solubility of hydrocarbon solutes in perfluorocarbon solvents, thereby improving the grease cleaning efficiency of perfluorocarbon-based solvents. Studies on the solubility enhancement and aggregation structure of these surfactants upon modification of their hydrocarbon lengths are described.; A system consisting of dimethyl octadecyl chains bonded to the surface of the (111) beta-cristobalite polymorph of silica is a good model to study retention mechanisms in RPLC. By varying the water to methanol ratio, the influence of the mobile phase composition on the structure of the bonded phase and on the solvent partitioning are investigated. |
