Ph.D., University of Arizona
Few analytical methods are truly specific for a single species. As a result, problems in chemical analysis frequently involve a preliminary separation step to isolate the species of interest from matrix constituents and from potential interferents. Chemical separations play an equally important role in many preparative and process-scale applications, the preparation of high-purity radiopharmaceuticals and the reprocessing of spent nuclear fuel representing just two of many possible examples.
In general terms, the goal of our research is to devise improved reagents, media, and processes for the separation and preconcentration of metal ions and organic molecules, and to explore the fundamental chemistry underlying their use. Of particular interest is the development of environmentally benign approaches to chemical separations. Within this broad framework lie two specific areas of study: room-temperature ionic liquids (RTILs) and supercritical fluids (SCFs). Supercritical fluids comprise a unique class of solvents with properties intermediate between those of a liquid and a gas.
Ionic liquids, unlike SCFs or conventional molecular solvents, consist entirely of ions, and as a result, exhibit a wide variety of interesting and useful properties.
Both classes of solvents show enormous potential as replacements for the toxic and volatile organic solvents employed in many separation processes, in part a result of their extraordinary tunabililty. In the case of SCFs, simply changing the temperature or pressure can significantly alter the solvent properties of the fluid. Similarly, for RTILs, minor changes in the nature of the cation or anion comprising the solvent can lead to dramatic changes in its behavior. It is this tunability that we seek to exploit in developing improved methods of separation.
Our recent work in this area has focused on three topics:
Progress in these areas is expected to provide the basis of efficient and selective "green" approaches to the separation of metal ions and organic molecules from a variety of complex matrices.