Authors: Patricia Paviet-Hartmann1, Joshua Pak2, Eric Brown3, Jared Horkley1, Earle Wolfrom1
Affiliation: (1) Idaho State
University/Idaho National Laboratory, (2)
Title: Extraction of Perrhenate and Pertechnetate by Crown Ethers
Abstract: The long half-life of
technetium-99 and its ability to form an anionic species makes it a major
concern when considering long-term disposal of high-level radioactive waste.
Furthermore, as its most stable species in the environment, the
pertechnetate ion, TcO4- is highly mobile and is considered as a long-term
hazard in nuclear waste disposal.
Because of the small activities of technetium-99 relative to other fission
products cesium-137 or strontium-90, and its long half-life time (t1/2 = 2.1 E5
yrs), technetium-99 is one of the key isotopes that should always be analyzed in
the radioactive liquid waste streams from the reprocessing industry where the
largest concentrations are to be expected.
However, since this radionuclide is a pure beta-emitter, tedious and
time-consuming chemical separations are usually performed prior to any
measurement in such complex media.
There is a need for the development of new extractant systems, such as systems
based on crown ethers that may serve to selectively extract and separate this
long lived radionuclide from different streams for potential industrial
application. In this paper, we are
reporting the design and synthesis of new macrocyclic compounds to selectively
extract technetium and rhenium from complex mixtures.
These macromolecules can be functionalized with oxygen, sulfur, and
nitrogen donating functional groups with various cavity sizes and/or bonding
modes. Preliminary tests have been
performed for the selective extraction of pertechnetate and perrhenate, and will
be presented.