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首页> 外文期刊>Environmental Science & Technology >Reduction of Uranium(VI) by Soluble Iron(ll) Conforms with Thermodynamic Predictions
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Reduction of Uranium(VI) by Soluble Iron(ll) Conforms with Thermodynamic Predictions

机译：溶解铁（II）还原铀（VI）符合热力学预测

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摘要

Soluble Fe(II) can reduce soluble U(VI) at rapid rates and in accordance with thermodynamic predictions. This was established by initially creating acidic aqueous solutions in which the sole oxidants were soluble U(VI) species and the sole reductants were soluble Fe(II) species. The pH of the solution was then increased by stepwise addition of OH", thereby increasing the potential for electron transfer from Fe(II) to U(VI). For each new pH value resulting from addition of base, values of AG for the Fe(II)-mediated reduction of U(VI) were calculated using the computed distribution of U and Fe species and possible half reaction combinations. For initial conditions of pH 2.4 and a molar ratio of Fe(II) to U(VI) of 5:1 (l mM Fe(II) and 0.2 mM U(VI)), AG for U(VI) reduction was greater than zero, and U(VI) reduction was not observed. When sufficient OH" was added to exceed the computed equilibrium pH of 5.4, AG for U(VI) reduction was negative and soluble Fe(II) species reacted with U(VI) in a molar ratio of ~2:1. X-ray absorption near-edge structure (XANES) spectroscopy confirmed production of U(IV). A decrease in pH confirmed production of acidity as the reaction advanced. As solution pH decreased to the equilibrium value, the rate of reaction declined, stopping completely at the predicted equilibrium pH. Initiation of the reaction at a higher pH resulted in a higher final ratio of U(IV) to U(VI) at equilibrium.
机译：可溶性Fe（II）可以快速且根据热力学预测还原可溶性U（VI）。这是通过首先创建酸性水溶液而建立的，其中唯一的氧化剂为可溶的U（VI）物种，唯一的还原剂为可溶的Fe（II）物种。然后通过逐步添加OH”来增加溶液的pH值，从而增加了电子从Fe（II）转移到U（VI）的可能性。对于每个因添加碱而产生的新pH值，Fe的AG值（II）介导的U（VI）还原是使用U和Fe物种的分布以及可能的半反应组合计算的，初始条件为pH 2.4，Fe（II）与U（VI）的摩尔比为5 ：1（1 mM Fe（II）和0.2 mM U（VI）），用于U（VI）还原的AG大于零，未观察到U（VI）还原。当添加足够的OH“超过计算值时平衡pH值为5.4，用于还原U（VI）的AG为负，可溶性Fe（II）物种与U（VI）的摩尔比为〜2：1。 X射线吸收近边缘结构（XANES）光谱证实了U（IV）的产生。随着反应的进行，pH的降低证实了酸度的产生。随着溶液pH降低至平衡值，反应速率下降，完全停止在预测的平衡pH下。在较高的pH下引发反应会导致平衡时U（IV）与U（VI）的最终比率更高。

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  • 来源
    《Environmental Science & Technology》 |2011年第11期|p.4718-4725|共8页
  • 作者

    Xin Du; Benjaporn Boonchayaanant; Wei-Min Wu; Scott Fendorf; John Bargar; Craig S. Criddle;

  • 作者单位

    Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States;

    Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States;

    Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States;

    Department of Environmental Earth System Sciences, Stanford University, Stanford, California 94305, United States;

    Stanford Synchrotron Radiation Laboratory (SSRL), Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory,Stanford, California 94305, United States;

    Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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