Award Date

12-1-2014

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Committee Member

Kenneth R. Czerwinski

Second Committee Member

Frederic Poineau

Third Committee Member

Alfred P. Sattelberger

Fourth Committee Member

Ralf Sudowe

Number of Pages

251

Abstract

Technetium is the lightest radioelement. The isotope 99Tc has around a 6% yield from 235U with a half-life of 2.13 x 105 years. The high mobility of TcO4-, the common chemical form of technetium in the environment makes 99Tc an isotope of concern in nuclear waste management. Despite its important role in radiopharmaceuticals and in the nuclear fuel cycle, the fundamental chemistry of technetium is not as well developed as that of the neighboring transition metals; one of the most striking examples being its sulfide chemistry.

Only two technetium binary sulfide compounds had been reported: Tc2S7 and TcS2. Even though technetium heptasulfide was studied, with some uncertainty in its solid state characterization, the speciation of the supernate during the reaction had never been explored. Reactions of pertechnetate in various sulfuric acid molarities with hydrogen sulfide were studied. Precipitates and supernates were analyzed by X-ray Absorption Fine Structure (XAFS) and UV-Visible spectroscopy. While TcS2 has been unambiguously characterized and synthesized, new routes of synthesis were explored and the solids obtained were analyzed by XAFS spectroscopy. Synthesis of ternary technetium sulfides in acetonitrile with bis(trimethylsilyl) sulfide was also examined.

Those studies related to the synthesis and behavior of different technetium materials will permit an increase in the scientific knowledge related to technetium sulfide chemistry. They will improve the fundamental understanding of behavior of 99Tc in repository conditions, which are potentially varied, and thus improve waste forms development.

Keywords

Inorganic compounds – Synthesis; Radiochemistry; Speciation (Chemistry); Sulfides; Synthetic chemistry; Technetium; Technetium compounds; X-ray Absorption Spectroscopy

Disciplines

Chemistry | Radiochemistry

File Format

pdf

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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