AN INVESTIGATION OF TRANSPORT PROPERTIES AND ION ASSOCIATION IN ROOM TEMPERATURE HALOALUMINATE MOLTEN SALTS

The physical and transport properties of the ionic liquid formed from mixtures of aluminum bromide with 1-methyl-3-ethylimidazolium bromide were investigated. A phase diagram, including glass transitions, was determined. Density data were fit to linear equations as functions of both composition and temperature. The non-Arrhenius behavior of this system was attributed to its glass forming properties. Viscosity and conductivity data were fitted to the Vogel-Tammann-Fulcher equation as functions of composition and temperature in order to get the temperature dependent activation energies for these transport properties.; Internal transport numbers relative to halide ion and external transport numbers relative to a porous barrier were determined across the composition region 0.30 {dollar}<{dollar} X{dollar}sb{lcub}rm Al{rcub}{dollar} {dollar}<{dollar} 0.50 for the aluminum chloride-1-methyl-3-ethylimidazolium chloride ionic liquid and across the composition region 0.30 {dollar}<{dollar} X{dollar}sb{lcub}rm Al{rcub} < 0.71{dollar} for the aluminum bromide-1-methyl-3-ethylimidazolium bromide melt system. Models are proposed for both systems. The internal transport number of the organic cation was found to be unity in the chloroaluminate system. This indicates that the anionic mobilities in this system are approximately equal, and it permits the use of simplified equations to represent the EMF of concentration cells. In contrast, the tetrabromoaluminate ion was shown to have greater mobility than either the bromide ion or the heptabromoaluminate ion in all but the most acidic bromide melts that were studied.; Anion-cation association was investigated in several haloaluminate ionic liquids by {dollar}sp1{dollar}H and {dollar}sp{lcub}13{rcub}{dollar}C NMR spectroscopy across the composition range 0 {dollar}le{dollar} X{dollar}sb{lcub}rm Al{rcub} le{dollar} 0.50. Both a two parameter model, which takes into account simple ion pairing, and a three parameter model, which takes into account more extensive interactions, were examined. It was found that the latter model best fits the experimental data.