Reinig Kimberly M, Seibert Rachel, Velazquez Daniel, Baumeister Jakob, Najafi Khosroshahi Firouzeh, Wycoff Wei, Terry Jeff, Adams John E, Deakyne Carol A, Jurisson Silvia S
Department of Physics, Illinois Institute of Technology , Chicago, Illinois 60616, United States.
Inorg Chem. 2017 Nov 6;56(21):13214-13227. doi: 10.1021/acs.inorgchem.7b02001. Epub 2017 Oct 10.
Technetium-99 (Tc) is important to the nuclear fuel cycle as a long-lived radionuclide produced in ∼6% fission yield from U or Pu. In its most common chemical form, namely, pertechnetate (TcO), it is environmentally mobile. In situ hydrogen sulfide reduction of pertechnetate has been proposed as a potential method to immobilize environmental TcO that has entered the environment. Reactions of TcO with sulfide in solution result in the precipitation of TcS except when olefinic acids, specifically fumaric or maleic acid, are present; a water-soluble Tc species forms. NMR (H, C, and 2D methods) and X-ray absorption spectroscopy [XAS; near-edge (XANES) and extended fine structure (EXAFS)] studies indicate that sulfide adds across the olefinic bond to generate mercaptosuccinic acid (HMSA) and/or dimercaptosuccinic acid (HDMSA), which then chelate(s) the Tc to form [TcO(MSA)], [TcO(DMSA)], or potentially [TcO(MSA)(DMSA)]. 2D NMR methods allowed identification of the products by comparison to Tc and nonradioactive rhenium standards. The rhenium standards allowed further identification by electrospray ionization mass spectrometry. TcO is essential to the reaction because no sulfide addition occurs in its absence, as determined by NMR. Computational studies were performed to investigate the structures and stabilities of the potential products. Because olefinic acid is a component of the naturally occurring humic and fulvic acids found in soils and groundwater, the viability of in situ hydrogen sulfide reduction of environmental TcO as an immobilization method is evaluated.
锝-99（Tc）作为一种长寿命放射性核素，在核燃料循环中具有重要意义，它由铀或钚的约6%裂变产额产生。在其最常见的化学形式即高锝酸盐（TcO）中，它在环境中具有迁移性。有人提出通过原位硫化氢还原高锝酸盐作为固定已进入环境的环境高锝酸盐的一种潜在方法。溶液中高锝酸盐与硫化物的反应会导致硫化锝沉淀，除非存在烯酸，特别是富马酸或马来酸，此时会形成一种水溶性锝物种。核磁共振（氢、碳和二维方法）和X射线吸收光谱[XAS；近边（XANES）和扩展精细结构（EXAFS）]研究表明，硫化物会加成到烯烃键上生成巯基琥珀酸（HMSA）和/或二巯基琥珀酸（HDMSA），然后它们螯合锝形成[TcO(MSA)]、[TcO(DMSA)]或可能[TcO(MSA)(DMSA)]。二维核磁共振方法通过与锝和非放射性铼标准物比较来鉴定产物。铼标准物通过电喷雾电离质谱法进行进一步鉴定。核磁共振确定，高锝酸盐对该反应至关重要，因为在其不存在时不会发生硫化物加成。进行了计算研究以探究潜在产物的结构和稳定性。由于烯酸是土壤和地下水中天然存在的腐殖酸和富里酸的组成部分，因此评估了原位硫化氢还原环境高锝酸盐作为一种固定方法的可行性。
