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首页> 外文期刊>Environmental Science & Technology >Effect of Reaction Pathway on the Extent and Mechanism of Uranium(Ⅵ) Immobilization with Calcium and Phosphate
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Effect of Reaction Pathway on the Extent and Mechanism of Uranium(Ⅵ) Immobilization with Calcium and Phosphate

机译：反应途径对钙和磷酸盐固定铀（Ⅵ）的程度和机理的影响

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摘要

Phosphate addition to subsurface environments contaminated with uranium can be used as an in situ remediation approach. Batch experiments were conducted to evaluate the dependence of the extent and mechanism of uranium uptake on the pathway for reaction with calcium phosphates. At pH 4.0 and 6.0 uranium uptake from solution occurred via autunite (Ca(UO_2)_2(PO_4)_2) precipitation irrespective of the starting forms of calcium and phosphate. At pH 7.5, a condition at which calcium phosphate solids could form, the uptake mechanism depended on the nature of the calcium and phosphate as determined by X-ray absorption spectros-copy and laser-induced fluorescence spectroscopy. When dissolved uranium, calcium, and phosphate were added simultaneously, uranium was structurally incorporated into a newly formed amorphous calcium phosphate solid. Adsorption was the dominant removal mechanism for uranium contacted with preformed amorphous calcium phosphate solids. When U(Ⅵ) was added to a suspension containing amorphous calcium phosphate solids as well as dissolved calcium and phosphate, then removal occurred through precipitation (57 ± 4%) of autuntte and adsorption (43 ± 4%) onto calcium phosphate. Dissolved uranium, calcium, and phosphate concentrations with saturation index calculations helped identify removal mechanisms and determine thennodynamically favorable solid phases.
机译：将磷酸盐添加到被铀污染的地下环境中可以用作原位修复方法。进行批处理实验以评估铀吸收程度和机理对与磷酸钙反应的途径的依赖性。在pH 4.0和6.0时，无论钙和磷酸盐的起始形式如何，都会通过金铁矿（Ca（UO_2）_2（PO_4）_2）沉淀从溶液中吸收铀。在pH 7.5（可能形成磷酸钙固体的条件）下，其吸收机理取决于X射线吸收光谱法和激光诱导荧光光谱法测定的钙和磷酸盐的性质。当同时添加溶解的铀，钙和磷酸盐时，铀会在结构上掺入新形成的无定形磷酸钙固体中。吸附是铀与预先形成的无定形磷酸钙固体接触的主要去除机理。当将U（Ⅵ）添加到含有无定形磷酸钙固体以及溶解的钙和磷酸盐的悬浮液中时，通过沉淀（57±4％）的自发沉淀并吸附（43±4％）到磷酸钙上而进行去除。计算出的饱和指数计算出的铀，钙和磷酸盐的浓度有助于确定去除机理并确定动力学上有利的固相。

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  • 来源
    《Environmental Science & Technology》 |2016年第6期|3128-3136|共9页
  • 作者

    Vrajesh S. Mehta; Fabien Maillot; Zheming Wang; Jeffrey G. Catalano; Daniel E. Giammar;

  • 作者单位

    Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States;

    Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States;

    Department of Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States;

    Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States;

    Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, 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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