Статья

Complexation of Uranium(VI) by Gluconate in Acidic Solutions: a Thermodynamic Study with Structural Analysis

Zhicheng ZhangChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, ItalyGregory L. HelmsChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, ItalySue B. ClarkChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, ItalyGuoxin TianChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, ItalyP. ZanonatoChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, ItalyLinfeng RaoChemistry Department and Center for NMR Spectroscopy, Washington State University, Pullman, Washington 99164, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, 35131, Padova, Italy

2009en

ABI

Аннотация

Within the pC(H) range of 2.5 to 4.2, gluconate forms three uranyl complexes UO(2)(GH(4))(+), UO(2)(GH(3))(aq), and UO(2)(GH(3))(GH(4))(-), through the following reactions: (1) UO(2)(2+) + GH(4)(-) = UO(2)(GH(4))(+), (2) UO(2)(2+) + GH(4)(-) = UO(2)(GH(3))(aq) + H(+), and (3) UO(2)(2+) + 2GH(4)(-) = UO(2)(GH(3))(GH(4))(-) + H(+). Complexes were inferred from potentiometric, calorimetric, NMR, and EXAFS studies. Correspondingly, the stability constants and enthalpies were determined to be log beta(1) = 2.2 +/- 0.3 and DeltaH(1) = 7.5 +/- 1.3 kJ mol(-1) for reaction (1), log beta(2) = -(0.38 +/- 0.05) and DeltaH(2) = 15.4 +/- 0.3 kJ mol(-1) for reaction (2), and log beta(3) = 1.3 +/- 0.2 and DeltaH(3) = 14.6 +/- 0.3 kJ mol(-1) for reaction (3), at I = 1.0 M NaClO(4) and t = 25 degrees C. The UO(2)(GH(4))(+) complex forms through the bidentate carboxylate binding to U(VI). In the UO(2)(GH(3))(aq) complex, hydroxyl-deprotonated gluconate (GH(3)(2-)) coordinates to U(VI) through the five-membered ring chelation. For the UO(2)(GH(3))(GH(4))(-) complex, multiple coordination modes are suggested. These results are discussed in the context of trivalent and pentavalent actinide complexation by gluconate.

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Идентификаторы

DOI: 10.1021/ic8018925

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Цитирований: 3Использованных источников: 0

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