A first-principle flotation model was derived at Virginia Tech from the basic mechanisms involved in the bubble-particle and bubble-bubble interactions occurring in a flotation cell (Yoon and Mao, 1996; Sherrell and Yoon, 2005; Do, H, 2010). The model consists of a series of analytical equations for bubble generation, bubble-particle collision, attachment, detachment, and froth phase recovery. The process of bubble-particle attachment has been modelled on the premise that bubble-particle attachment occurs when the disjoining pressure of the thin liquid in a wetting films formed between particle and bubble is negative, as was first suggested by Laskowski and Kitchener (1969). These provisions allow for the flotation model to incorporate various chemistry parameters such as zeta-potentials, contact angles, surface tension in addition to the physical and hydrodynamic parameters such as particle size, bubble size, and energy dissipation rate. In the present work, the effects of both hydrodynamic and chemistry parameters have been studied using the model-based computer simulator. A series of laboratory batch flotation experiments carried out on mono-sized glass beads validated the simulation results. The flotation feeds were characterized in terms of particle size, contact angle, and Hamaker constant, and the flotation experiments were conducted at different energy dissipation rates, gas rates, froth heights. The flotation tests were also carried out on mixtures of hydrophobic silica and hydrophilic magnetite particles, so that the grades of the flotation products can be readily determined by magnetic separation. The experimental results are in good agreement with the model predictions both in terms of grade and recovery. / Master of Science

<p>Liquid Chromatography (LC) and Capillary Electrophoresis (CE) are modern analytical techniques that play very important roles in many areas of modern science such as life science, biotechnology, biomedicine, environmental studies, and development of pharmaceutics. Even though these two techniques have existed and been subjected to studies for several decades, the developments of new separation materials for them are still very important till now in order to meet the different new demands for improvement from other disciplines in science.</p><p>In this doctoral thesis, several novel covalently bonded sulfobetaine type zwitterionic separation materials are synthesized for the application in LC and CE. These materials carry both positively charged quaternary ammonium groups and negatively charged sulfonic groups, which result in a very low net surface charge compared to conventional separation materials with only anionic or cationic functional groups. Consequently, it is possible to employ these materials for separation of different ionic species under mild conditions. The surface properties have also been characterized, mainly by elemental analysis, sorption isotherm, ζ-potential measurements, and spectroscopic methods.</p><p>By using packed zwitterionic columns for liquid chromatography, small inorganic anions or cations, and acidic or basic proteins can be independently and simultaneously separated in a single run using optimal sets of separation conditions. This is a unique property compared to conventional ionic separation material for LC. When fused silica capillaries coated with zwitterionic polymer are used for capillary electrophoresis, good separations can be achieved for solutes as different as inorganic anions, peptides, proteins, and tryptically digested proteins.</p>

Liquid Chromatography (LC) and Capillary Electrophoresis (CE) are modern analytical techniques that play very important roles in many areas of modern science such as life science, biotechnology, biomedicine, environmental studies, and development of pharmaceutics. Even though these two techniques have existed and been subjected to studies for several decades, the developments of new separation materials for them are still very important till now in order to meet the different new demands for improvement from other disciplines in science. In this doctoral thesis, several novel covalently bonded sulfobetaine type zwitterionic separation materials are synthesized for the application in LC and CE. These materials carry both positively charged quaternary ammonium groups and negatively charged sulfonic groups, which result in a very low net surface charge compared to conventional separation materials with only anionic or cationic functional groups. Consequently, it is possible to employ these materials for separation of different ionic species under mild conditions. The surface properties have also been characterized, mainly by elemental analysis, sorption isotherm, ζ-potential measurements, and spectroscopic methods. By using packed zwitterionic columns for liquid chromatography, small inorganic anions or cations, and acidic or basic proteins can be independently and simultaneously separated in a single run using optimal sets of separation conditions. This is a unique property compared to conventional ionic separation material for LC. When fused silica capillaries coated with zwitterionic polymer are used for capillary electrophoresis, good separations can be achieved for solutes as different as inorganic anions, peptides, proteins, and tryptically digested proteins.