UNLV Theses, Dissertations, Professional Papers, and Capstones 12-1-2014 Technetium Sulfide: undamentalF Chemistry for Waste Storage Form's Application Maryline Ghislaine Ferrier University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Radiochemistry Commons Repository Citation Ferrier, Maryline Ghislaine, "Technetium Sulfide: undamentalF Chemistry for Waste Storage Form's Application" (2014). UNLV Theses, Dissertations, Professional Papers, and Capstones. 2259. http://dx.doi.org/10.34917/7048578 This Dissertation is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. 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TECHNETIUM SULFIDE: FUNDAMENTAL CHEMISTRY FOR WASTE STORAGE FORM’S APPLICATION By Maryline Ferrier Bachelor of Science in Chemistry Institut National des Sciences Appliquées de Rouen, France 2006 Master of Science in Chemistry Institut National des Sciences Appliquées de Rouen, France 2008 A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy - Radiochemistry Department of Chemistry College of Sciences The Graduate College University of Nevada, Las Vegas December 2014 Copyright by Maryline Ferrier, 2015 All Rights Reserved We recommend the dissertation prepared under our supervision by Maryline Ferrier entitled Technetium Sulfide: Fundamental Chemistry for Waste Storage Form’s Application is approved in partial fulfillment of the requirements for the degree of Doctor of Philosophy - Radiochemistry Department of Chemistry Kenneth Czerwinski, Ph.D., Committee Chair Frederic Poineau, Ph.D., Committee Member Alfred Sattelberger, Ph.D., Committee Member Ralf Sudowe, Ph.D., Graduate College Representative Kathryn Hausbeck Korgan, Ph.D., Interim Dean of the Graduate College December 2014 ii ABSTRACT Technetium Sulfide: Fundamental Chemistry for Waste Storage Form’s Application By Maryline Ferrier Dr. Kenneth Czerwinski, Advisory Committee Chair Professor of Chemistry University of Nevada, Las Vegas Technetium is the lightest radioelement. Thirty four isotopes are known, the two 99m 99 99m main isotopes being Tc and Tc. The isotope Tc (T1/2 = 6.01 hours, γ = 140.5 keV) is 99 5 used for diagnostics in nuclear medicine, while Tc (T1/2 = 2.13 x 10 years, β = 294 keV) is a major fission product of the nuclear industry with about 6% yield from 235U by thermal neutrons. Technetium exhibits nine oxidation state (-I to VII) and an extensive set of mixed oxidation states due to polynuclear complex formation. Under oxidizing conditions between pH 0 and 14, the aqueous chemistry of Tc(VII) is dominated by the - TcO4 which is highly mobile in the environment. The high production rate, mobility, long half-life and radiotoxicity make 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 iii neighboring transition metals; one of the most striking examples being its sulfide chemistry. Only two technetium 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, Tc2S7, were analyzed by Energy Dispersive X-ray (EDX) and X-ray Absorption Fine Structure (XAFS) spectroscopy and compared to previous studies and other transition metal sulfide characterizations. Analyses of the supernates by UV-Visible and XAFS spectroscopies were able to suggest speciation of pertechnetate in sulfuric acid under reducing conditions. 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. iv ACKNOWLEDGMENTS This work would not have been possible without the help of my advisor, Pr. Kenneth Ronald Czerwinski, who I thank for being a great advisor these few years. I would like also to thank him and all the committee members for giving me the opportunity to participate to the radiochemistry program at UNLV. It was a real pleasure to be a part of this team again. Thank you to my committee members for their inputs and suggestions. Specially, I would like to thank Dr. Frédéric Poineau, research professor within Ken’s team for providing me with useful and helpful assistance and contribution throughout my laboratory work. I also would like to thank Dr. Alfred Sattelberger for his help by giving me new ideas to explore and reviewing the papers for publication. I appreciate the radiochemistry group as a whole, and especially Julie Bertoia and Trevor Low for making the laboratory works efficiently. And thank you to my labmates for their advice, help and friendship. Finally, thank you to my family and friends for their support during all of those hours of doubt and stress. v TABLE OF CONTENTS ABSTRACT ...................................................................................................................... iii ACKNOWLEDGMENTS .................................................................................................... v TABLE OF CONTENTS..................................................................................................... vi LIST OF TABLES .............................................................................................................. xi LIST OF FIGURES ......................................................................................................... xvii CHAPTER 1: INTRODUCTION ......................................................................................... 1 1.1 Background....................................................................................................... 1 1.2 Technetium background .................................................................................. 5 1.3 Sulfur Chemistry ............................................................................................... 8 1.4 Transition metal sulfides ................................................................................ 12 1.4.1 Tetrathio-metallates ............................................................................... 13 1.4.2 d0 configuration for transition metal sulfides ......................................... 14 1.4.3 Disulfides ................................................................................................. 15 1.4.4 Technetium sulfides ................................................................................ 17 1.4.5 Transition metals comparison ................................................................. 19 1.5 Redox potential for manganese, technetium and rhenium .......................... 21 CHAPTER 2: Materials and Methods ........................................................................... 23 vi 2.1 Materials and methods used ......................................................................... 23 2.1.1 Synthesis of starting compounds ............................................................ 24 2.1.1.1 Tc(VII) ............................................................................................... 24 2.1.1.1.1 Preparation of NH4TcO4 ............................................................ 25 2.1.1.1.2 Preparation of KTcO4 ................................................................. 25 2.1.1.1.3 Preparation of (Bu4N)TcO4 ........................................................ 26 2.1.1.2 Tc(VI) ................................................................................................ 26 2.1.1.3 Tc(V) ................................................................................................. 27 2.1.1.4 Tc(IV) ................................................................................................ 28 2.1.1.4.1 Preparation of K2TcCl6 ............................................................... 28 2.1.1.4.2 Preparation of TcCl4 .................................................................. 29 2.1.1.5 Tc(0) .................................................................................................. 31 2.2 Characterization techniques .......................................................................... 32 2.2.1 Primary techniques ................................................................................