Uranium uptake by phosphate minerals at hydrothermal conditions
Uranium uptake by phosphate minerals at hydrothermal conditions
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磷酸盐矿物在热液条件下对铀的吸收
DOI：
10.1016/j.chemgeo.2023.121581
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发表时间：
2023
期刊：
影响因子：
3.9
通讯作者：
Perez-Huerta, Alberto
中科院分区：
文献类型：
--
作者：
Jiménez-Arroyo, Ángel;Gabitov, Rinat;Migdisov, Artas;Lui, Juejing;Strzelecki, Andrew;Zhao, Xiaodong;Guo, Xiaofeng;Paul, Varun;Mlsna, Todd;Perez-Huerta, Alberto
这项工作的目的是评估通过磷酸钙矿物（磷酸盐）的结晶来固定铀（U），磷酸钙矿物具有很强的吸收和保留溶解铀酰的能力，因此，在各种地质和环境应用中是有用的。迄今为止，大多数实验研究都是在室温和高温下进行的，对铀固定的评估依赖于外推程序，这并不总是准确的。为了评估铀在磷酸盐和热液流体之间的分配系数，我们在25-350° C和各种含水铀浓度下进行了一系列结晶实验。在掺铀水溶液中透钙磷石向三斜磷钙石或/和磷灰石的转化过程中发生了结晶。采用X射线衍射（XRD）和扫描电子显微镜（SEM）对固体产物进行了表征。用X射线吸收光谱法测定了磷灰石中铀的局部成键环境和价态。用电感耦合等离子体质谱法（ICP-MS）测定了晶体和共存溶液中铀的浓度。表观分配系数计算为能斯特分配系数（D U）和Doener-Hoskins分配系数（K D− H U/Ca）（考虑封闭储层效应）。实验的DU值进行了比较与使用晶格应变模型计算。结果表明，通过这种结晶方法提取了添加到溶液中的> 92%的U，并且随着磷酸盐结晶温度的升高，K D− HU/Ca降低。因此，磷酸盐，特别是磷灰石，具有很强的潜力，在水热条件下，可用于开发工程屏障，以进一步提高现有回填材料在核废料处理中的效率。
The goal of this work was to evaluate the immobilization of uranium (U) through crystallization of calcium phosphate minerals (phosphates), which have a strong ability to absorb and retain dissolved uranyl, and therefore, are useful in various geological and environmental applications. To date, most of the experimental studies have been conducted at room temperature and high temperature assessments on uranium immobilization rely on the extrapolation procedure, which is not always accurate. To evaluate uranium partition coefficients between phosphates and hydrothermal fluid, we performed a series of crystallization experiments at 25–350° C and various aqueous uranium concentrations. Crystallization occurred through the transformation of brushite to monetite or/and apatite in aqueous solutions doped with uranium aliquots. Solid products were extracted and characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The local bonding environment and valence state of uranium in apatite were determined via X-ray absorption spectroscopy (XAS). Uranium concentration in crystals and coexisting solutions were measured with inductively coupled plasma mass spectrometry (ICP-MS). Apparent partition coefficients were calculated as Nernst partition coefficients (D U) and Doener-Hoskins partition coefficients (K D− H U/Ca)(to account for closed reservoir effect). Experimental D U values were compared with those calculated using the lattice strain model. Results showed that> 92% of U added to solutions was extracted via this crystallization method and K D− H U/Ca decreases with increasing phosphate crystallization temperature. Thus, phosphates, especially apatite, has a strong potential to immobilize uranium under hydrothermal conditions and can be used in the development of engineering barriers to further improve the efficiency of existing backfill materials in the disposal of nuclear waste.
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DOI：
--
发表时间：
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期刊：
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