No description available.

No description available.

This thesis describes the synthesis and characterization of triaminocyclopropenium, [C3(NR2)3]+, ionic liquids. A range of triaminocyclopropenium salts were prepared: D3h, C3h, C2v and Cs symmetric cations with a variety of substituents. D3h and C3h symmetric cations were prepared from pentachlorocyclopropane and dialkylamines, whereas a variety of methods were investigated for C2v and Cs symmetric cations, with the most versatile synthesis involving the alkylation of bis(dialkylamino)cyclopropenone followed by reaction with dialkylamine. Metathesis with a range of common ionic liquid anions was carried out to facilitate comparisons to other common classes of ionic liquids. The triaminocyclopropenium salts were characterized by standard techniques (1H-, 13C{1H}-NMR, ES+ MS, microanalysis) as well as particular physicochemical properties relevant to ionic liquids. The thermal behaviour was examined with DSC, with the majority of salts being liquid at room temperature. The viscosity of triaminocyclopropenium ionic liquids was similar to other classes of ionic liquid cations, in the range of 58.4 to 554 mPa s at 20 °C. This is despite the generally large size of the cations investigated, which also causes the conductivity to be lower. Triaminocyclopropenium ionic liquids show good ionicity, more than other common classes of ionic liquid cation, which is likely due to the relatively electron-rich nature of the cation. The thermal, electrochemical and chemical stability of triaminocyclopropenium ionic liquids was accessed. Good thermal stabilities were observed, with onset temperatures of 339 to 413 °C. The electrochemical window of [C3(NEt2)3]TFSA is 3.6 V, this is low due to the easy oxidation of the cation. The chemical stability is good under acidic, weakly-basic, weakly-nucleophilic, reducing and weakly-oxidising conditions, however, the cations are unstable to the strong nucleophile/base hydroxide. Triaminocyclopropenium ionic liquids showed a full range of solubility and miscibility: from fully miscible in water to fully miscible in hexane. A preliminary investigation of ionic liquid fluorides was carried out. While stable ionic liquids with naked fluorides were not obtained, ionic liquids with strongly-bound solvate molecules (ethanol and acetic acid) were seeen, and their viscosity, conductivity and density were measured. The attachment of hydroxyl functional groups to triaminocyclopropenium cations was seen to improve the stability of ionic liquid fluorides, although at the cost of high viscosity.

No description available.

Thermodynamic modelling is a relatively new technique with which to study the interactions of ionic species in solution. Using the computer program PHREEQE, and the modified version PHRQPITZ, the effects of a range of reactive anions and cations on the components of cementitious systems are studied with respect to cement barrier performance in a nuclear waste repository. A review is made of the underlying thermodynamic theory, and of the development of the technique of thermodynamic modelling, before concentrating on the program PHREEQE and the method by which it performs calculations. The technique is then applied to the CaO-SiO₂-H₂O system under the influence of sulfate, carbonate, chloride, arsenite, Na₂O, K₂O, NaCl and MgSO₄. The effects of NaCl and MgSO₄ on certain sub-systems within the CaO-Al₂O₃-H₂O system are also studied. It is calculated that Ca(OH)₂ and CSH are the main pH maintaining phases, of which CSH has the greater stability under the influence of the species considered. AFm and AFt phases also act as pH buffers, but they are quantitatively less important. A review is made of solid solutions between members of the AFm and AFt groups of minerals. Experimental methods are used to study the extent of solid solution between monosulfoaluminate and Friedel's salt, and between monosulfoaluminate and C₄AH₁₃. In the case of the former, no solid solution is observed, but an intermediate phase, designated Kuzel's salt, is observed. In the latter case, two areas of solid solution at low and high sulfate content, separated by a miscibility gap, are detected. No evidence is found to support the existence of calcium hemisulfoaluminate.

Ionic liquids are molten salts with melting points below 100 °C and they consist entirely of cations and anions. The development of ionic liquids, especially air and water stable types, has attracted extensive attention since they have outstanding physical properties. Part I of the study focused on the pre-electrolysis process performed to remove impurities from the ionic liquid, 1-butyl-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide, ([BMP]Tf2N). Part II investigated the electroreduction of TaF5 and NbF5 from room temperature ionic liquid at 100 °C at a wide range of potentials and different time durations for the purpose of determining the optimal conditions for the electrodeposition of tantalum. The study was carried out using potentiostatic polarization for the pre-electrolysis treatments and electrodeposition and cyclic voltammetry to study the behaviour of the liquid at various stages. Potentiostatic depositions were complemented by scanning electron microscopy (SEM)/energy-dispersive x-ray analysis (EDX), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) for characterization of the electrodeposits.

Ionic liquids are molten salts with melting points below 100 °C and they consist entirely of cations and anions. The development of ionic liquids, especially air and water stable types, has attracted extensive attention since they have outstanding physical properties. Part I of the study focused on the pre-electrolysis process performed to remove impurities from the ionic liquid, 1-butyl-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide, ([BMP]Tf2N). Part II investigated the electroreduction of TaF5 and NbF5 from room temperature ionic liquid at 100 °C at a wide range of potentials and different time durations for the purpose of determining the optimal conditions for the electrodeposition of tantalum. The study was carried out using potentiostatic polarization for the pre-electrolysis treatments and electrodeposition and cyclic voltammetry to study the behaviour of the liquid at various stages. Potentiostatic depositions were complemented by scanning electron microscopy (SEM)/energy-dispersive x-ray analysis (EDX), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) for characterization of the electrodeposits.

Thesis (Ph. D - Hydrology and Water Resources) - University of Arizona. / Includes bibliographical references (leaves 206-216).

Thesis (Ph.D)--University of Adelaide, 1957. / "November 1957." Includes bibliographical references.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Typescript. "References": leaves 82-83.