Integrated Computational and Experimental Protocol for Understanding Rh(III) Speciation in Hydrochloric and Nitric Acid Solutions

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• 作者：Alex C. Samuels ; Cherilynn A. Boele ; Kevin T. Bennett ; Sue B. Clark ; Nathalie A. Wall ; Aurora E. Clark
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：December 1, 2014
• 年：2014
• 卷：53
• 期：23
• 页码：12315-12322
• 全文大小：358K
• ISSN：1520-510X

文摘

Platinum group metals (PGMs), including rhodium, generated by the fission of ²³⁵U are present in significant quantities within spent nuclear fuel located on power generation sites in the United States, the amount of which is expected to exceed natural reserves by 2030. Yet, spent fuel raffinates are highly acidic media that may result in complex speciation of the PGM. This work provides an understanding of Rh(III) speciation up to 9 M HCl and HNO₃, and utilizes a combination of ultraviolet鈥搗isible (UV-vis) and capillary zone electrophoresis data, along with computationally predicted thermochemistry and simulated UV-vis spectra to approximate the relative concentrations of potential species in solution as a function of acid concentration. One Rh(III) species, [Rh(NO₃)₃], is observed under all conditions in HNO₃ and for Rh(III) concentrations smaller than 10^鈥? M. In contrast, a variety of chloridated Rh(III) species may exist simultaneously in a HCl medium. The species [RhCl₂(H₂O)₄]⁺ and [RhCl₃(H₂O)₃] are observed in HCl solutions of concentrations ranging from 0 to 1 M; the species [RhCl₄(H₂O)₂]^{鈭?/sup>, [RhCl₅(H₂O)]2鈥?/sup>, and [Rh₂Cl₉]3鈥?/sup> are observed between 2 and 9 M HCl.}