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Uranyl oxalate species in high ionic strength environments: stability constants for aqueous and solid uranyl oxalate complexes
Radiochimica Acta ( IF 1.4 ) Pub Date : 2021-03-01 , DOI: 10.1515/ract-2020-0083
Yongliang Xiong 1 , Yifeng Wang 1
Affiliation  

Uranyl ion, UO 2 2+ , and its aqueous complexes with organic and inorganic ligands can be the dominant species for uranium transport on the Earth surface or in a nuclear waste disposal system if an oxidizing condition is present. As an important biodegradation product, oxalate, C 2 O 4 2− , is ubiquitous in natural environments and is known for its ability to complex with the uranyl ion. Oxalate can also form solid phases with uranyl ion in certain environments thus limiting uranium migration. Therefore, the determination of stability constants for aqueous and solid uranyl oxalate complexes is important not only to the understanding of uranium mobility in natural environments, but also to the performance assessment of nuclear waste disposal. Here we developed a thermodynamic model for the UO 2 2+ –Na + –H + –Cl – –ClO 4 – –C 2 O 4 2– –NO 3 – –H 2 O system to ionic strength up to ∼11 mol•kg −1 . We constrained the stability constants for UO 2 C 2 O 4 (aq) and UO 2 (C 2 O 4 ) 2 2− at infinite dilution based on our evaluation of the literature data over a wide range of ionic strengths up to ∼11 mol•kg −1 . We also obtained the solubility constants at infinite dilution for solid uranyl oxalates, UO 2 C 2 O 4 •3H 2 O, based on the solubility data over a wide range of ionic strengths. The developed model will enable for the accurate stability assessment of oxalate complexes affecting uranium mobility under a wide range of conditions including those in deep geological repositories.

中文翻译:

高离子强度环境中的草酸铀酰酯种类:含水和固体草酸铀酰酯配合物的稳定性常数

如果存在氧化条件,铀酰离子,UO 2 2+及其与有机和无机配体的水络合物可能是铀在地球表面或核废料处理系统中运输的主要物质。草酸C 2 O 4 2-是一种重要的生物降解产物,在自然环境中无处不在,并具有与铀酰离子络合的能力。草酸盐在某些环境中还可以与铀酰离子形成固相,从而限制了铀的迁移。因此,确定含水草酸铀酰和固体草酸铀酰酯配合物的稳定常数,不仅对了解自然环境中铀的迁移性具有重要意义,而且对核废料处置的性能评估也很重要。在这里,我们为UO 2 2+ –Na + –H + –Cl – –ClO 4 – –C 2 O 4 2– –NO 3 – –H 2 O系统开发了一个热力学模型,离子强度高达〜11 mol•。千克-1。我们根据对离子强度高达11 mol的宽范围离子色谱数据的评估,限制了UO 2 C 2 O 4(aq)和UO 2(C 2 O 4)2 2-在无限稀释下的稳定性常数。 •kg -1。基于广泛的离子强度范围内的溶解度数据,我们还获得了固体草酰铀酰UO 2 C 2 O 4•3H 2 O在无限稀释下的溶解度常数。开发的模型将能够在广泛的条件下,包括在深部地质库中,对影响铀迁移率的草酸盐配合物进行准确的稳定性评估。我们根据对离子强度高达11 mol的宽范围离子色谱数据的评估,限制了UO 2 C 2 O 4(aq)和UO 2(C 2 O 4)2 2-在无限稀释下的稳定性常数。 •kg -1。基于广泛的离子强度范围内的溶解度数据,我们还获得了固体草酰铀酰UO 2 C 2 O 4•3H 2 O在无限稀释下的溶解度常数。开发的模型将能够在广泛的条件下,包括在深部地质库中,对影响铀迁移率的草酸盐配合物进行准确的稳定性评估。我们根据对离子强度高达11 mol的宽范围离子色谱数据的评估,限制了UO 2 C 2 O 4(aq)和UO 2(C 2 O 4)2 2-在无限稀释下的稳定性常数。 •kg -1。基于广泛的离子强度范围内的溶解度数据,我们还获得了固体草酰铀酰UO 2 C 2 O 4•3H 2 O在无限稀释下的溶解度常数。开发的模型将能够在广泛的条件下,包括在深部地质库中,对影响铀迁移率的草酸盐配合物进行准确的稳定性评估。基于各种离子强度的溶解度数据。开发的模型将能够在广泛的条件下,包括在深部地质库中,对影响铀迁移率的草酸盐配合物进行准确的稳定性评估。基于各种离子强度的溶解度数据。开发的模型将能够在广泛的条件下,包括在深部地质库中,对影响铀迁移率的草酸盐配合物进行准确的稳定性评估。
更新日期:2021-03-17
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