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Submitted in fulfillment of the academic requirements for the degree of Master in Engineering, Durban University of Technology, Durban, South Africa, 2017. / Phase equilibrium data plays a significant role in the design and optimization of industrial separation schemes, such as distillation and absorption units. These separation processes are utilised for the purification of valuable chemicals, which play a pivotal role in daily human life. Separation units are operated at various conditions of temperature and pressure, however it is common for most units to operate in the moderate pressure region (100-500 kPa). On the contrary, there is a lack of phase equilibrium data available in the moderate pressure region, thus prompting an interest in this area. In this study, a new static synthetic cell was tested, and the experimental apparatus was successfully set up and commissioned. Some key features of this design include a total working cell volume of 60 cm3 (which reduces the amount of chemicals required compared to conventional static synthetic cells) and equilibrium is achieved faster. In addition, two high-accuracy Teledyne Isco pumps were utilised for the feed loading, as it is vital that the volume of chemicals dispensed into the cell be accurately determined. The necessary calibrations were conducted and the overall uncertainties were found to be 0.06 K, 0.36 kPa and 0.1 ml for temperature, pressure and volume respectively. The following test systems were measured to determine the reproducibility of the apparatus and to verify the experimental technique: • water (1) + 2-butanol (2) at 323.16 K • n-hexane (1) + 2-butanol (2) at 329.21 K • n-pentane (1) + 1-propanol (2) at 317.18 K • n-pentane (1) + 2-butanol (2) at 303.17 K • n-pentane (1) + ethanol (2) at 303.11 K The test systems measured produced a good fit with the literature data, and thus the experimental apparatus was commissioned. New systems, previously unmeasured in the open literature, were measured in this study. These systems include: • n-hexane (1) + perfluoro-n-heptane (2) at 313.21 and 333.12 K • n-pentane (1) + 2-propanol (2) at 313.11, 323.11 and 333.12 K The data was modelled on Aspen Plus®. Since the method of operation is of the static synthetic type, no analysis of the vapour and liquid phases took place, and instead an algorithm was developed using the combined method (γ-ϕ) together with the method of Barker (1953), to convert the overall composition (zi) to liquid mole fraction (xi). The Wilson and Non-Random Two-Liquid (NRTL) activity coefficient models together with the Ideal Gas law and Hayden O’Connell second virial coefficient were utilised to regress the data. For both the fluorinated and alkane + alcohol systems, the experimental i data produced an excellent fit with the activity coefficient models. For both systems, azeotropes were observed, indicating poor separation of these binary combinations at specific mole fractions. This is due to the boiling point of both components being similar under certain conditions. The calculated pressure residuals were well within the overall combined uncertainty for pressure, whilst the calculated temperature residuals were slightly above the overall combined uncertainty for temperature. / M

Le besoin d’accès aux énantiomères purs a largement augmenté depuis les années 90. Les procédés ayant recours à la cristallisation sont souvent moins cher mais tout aussi efficace que les autres procédés. Deux études ont été réalisées dans cette thèse : -La première concerne l’amélioration d’un procédé déjà établi. En effet, l’efficacité de la Cristallisation Préférentielle (PC) de conglomérat est connue. Néanmoins, son application à des solutions solides images l’une de l’autre dans un miroir est plus complexe. Est présenté le premier exemple de PC réalisée sur un système à solution solide complète démixant à basse température : le sel d’hydrogénomaléate de baclofène (un API). De plus, il s’agit de la première preuve expérimentale d’un tel équilibre de phases et de PC de solutions solides dont les résultats sont comparables à la cristallisation préférentielle traditionnelle. -Le second sujet ne traite pas directement de la séparation d’énantiomère mais de prometteuses discriminations chirales ont été obtenues. Le diagramme d’équilibre de phases entre les compositions racémiques de deux couples d’atropoisomères a été étudié. Deux résultats en lien avec la discrimination chirale ont été établis : le premier est la possibilité de déracémiser un composé A initialement non-discriminé (composé racémique) à l’intérieur de la matrice d’un composé B discriminé (conglomérat). Le second est l’observation d’un nouveau type de chiralité : Chiralité Induite par Dissymmétrie de Distribution (CIDD). / The need for access to pure enantiomers has largely increased since the nineties. Processes using crystallization are often cheaper and as efficient as other processes. Thus, the improvement of existing techniques and the need for new processes are attractive for scientist and industry. Two studies have been performed in this thesis:The first one concerns the improvement of an existing technique. Indeed, conglomerate Preferential Crystallization efficiency is well known. Nonetheless, its application to mirror image partial solid solutions is more difficult. Here is presented the first example of PC performed on a complete solid solution at high temperature which shows a solid solutions demixion at low temperature: the baclofen hydrogenomaleate salt (an API). Moreover, it is the first experimental observation of such phase equilibria and PC of mirror image solid solutions whose results are comparable to classical PC. -The second topic did not involve directly enantiomer separation but promising chiral discriminations have been obtained. The phase diagram between the racemic composition of two couples of atropisomers has been defined. Beside multiples equilibria observed, two results concerning the chiral discrimination can be highlighted: the first one is the possibility to deracemize a compound A initially not discriminated (racemic compound) inside the matrix of a compound B (which forms a stable conglomerate). The second is the observation of a new kind of chirality: Chirality Induced by Dissymmetric Distribution (CIDD).

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 1977 / Vita. / Includes bibliographical references. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Materials Science and Engineering

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1978. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Mohammad Seyed Saiedfar. / M.S.

Ultra-pure reagents, platinum resistance thermometry and modern inert atmosphere glove box facilities have made possible a detailed examination of the NaK system at atmospheric pressure. A thermoanalytical study of solid-liquid phase equilibria in the NaK alloy system was conducted in the tetrahedral press to 55 kbars to investigate possible intermediate compound formation and shifting of the invariant points at various pressures. An expected shift in the eutectic composition to lower potassium content with an increase in the halt temperature on increasing pressure was confirmed. A merging of the meritectic and eutectic points at 343 ±2°K and 37 ±3 kbars occurred at 0.40 mole fraction K. Above 35 kbars the original meritectic halt behaves much like elemental cesium, suggesting new structural modifications. The possibility of a eutectoid with increased solid solubility limits is suggested for the invariant point which decreases with increasing pressure. The formation of NaK2 under pressure is suggested but not confirmed.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Vita. / Bibliography : leaves 446-473. / by Rateb M. Abu-Eid. / Ph.D.

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Bibliography: leaves 124-128. / by James R. Besancon. / Ph.D.

M.S.

The NaCaAlF₆-Al₂O₃ and Na₃AlF₆-Al₂O₃-NaCaAlF₆ phase diagrams were determined using DTA, x-ray diffraction, quench analysis, and optical microscopy. The NaCaAlF₆-Al₂O₃ system was a simple eutectic system with the eutectic located below 0.5 weight percent NaCaAlF₆. The ternary system was a eutectic system showing solid solution of NaCaAlF₆ in both polymorphs of Na₃AlF₆. Alumina exhibited no appreciable solubility in Na₃AlF₆ and, in the ternary system, less than 2% solubility above 15% NaCaAlF₆. / Master of Science