Aspects of the environmental chemistry of technetium.

摘要

Technetium-99 is a high yield daughter product from fission reactions. The chemistry of this isotope makes it an environmental contaminant that is difficult to remove. This dissertation describes three aspects regarding the chemistry of technetium and its chemical analog, rhenium.; The second chapter discusses a new method of extracting anionic metals from water with supercritical fluid carbon dioxide. Efficient extraction of tetrabutylammonium perrhenate was performed with methanol modified supercritical fluid carbon dioxide. This extraction was performed without complexation of rhenium prior to extraction. The third chapter examines the use of host-guest chemistry to selectively remove pertechnetate from aqueous systems. A metallated cyclotriveratrylene-type host selectively removed pertechnetate from saline at high efficiency in the presence of similar anions. The fourth chapter describes the possible use of technetium, in various chemical complexes, as a tracer for hydrological flows. Technetium-99m pharmaceuticals were added to different soils and water types to determine their sorption characteristics. Pertechnetate was found to have the lowest sorption while the complexed pharmaceuticals showed mixed, but higher, sorption.