Synthesis and thermodynamics of uranium-incorporated α-Fe2O3 nanoparticles
Synthesis and thermodynamics of uranium-incorporated α-Fe2O3 nanoparticles
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DOI：
10.1016/j.jnucmat.2021.153172
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发表时间：
2021-07-14
影响因子：
3.1
通讯作者：
Navrotsky, Alexandra
中科院分区：
文献类型：
--
作者：
Lam, Andy;Hyler, Forrest;Navrotsky, Alexandra
采用共沉淀-水热法在中性水溶液中合成了纳米级的赤铁矿。XRD、TEM和EXAFS分析表明，铀可能沿沿着晶界聚集并占据赤铁矿中的Fe位。所描述的合成方法产生不存在表面结合的铀酰络合物的结晶单相氧化铁纳米颗粒。EXAFS数据与现有研究的光谱相当，现有研究的合成更能代表自然发生的延长老化过程。这项工作提供并验证了一种加速合成铀固定氧化铁纳米粒子的方法，为进一步的机理研究。高温氧化物熔体溶液量热法测量进行计算的热力学稳定性的铀纳入氧化铁纳米粒子。赤铁矿中铀含量的增加导致了更积极的形成。当x = 0.037时，UxFe（2-2x）O（3）的标准生成能高达76.88 ± 2.83 kJ/mol（相对于其二元氧化物）或-764.04 ± 3.74 kJ/mol（相对于其组成元素）。关于铀保留途径的热力学稳定性的数据可能有助于预测废物铀酰的再活化，以及开发更有效的方法来保留从水环境中捕获的铀。(C)2021爱思唯尔有限公司版权所有。
Hematite nanoparticles were synthesized with U(VI) in circumneutral water through a coprecipitation and hydrothermal treatment process. XRD, TEM, and EXAFS analyses reveal that uranium may aggregate along grain boundaries and occupy Fe sites within hematite. The described synthesis method produces crystalline, single-phase iron oxide nanoparticles absent of surface-bound uranyl complexes. EXAFS data were comparable to spectra from existing studies whose syntheses were more representative of natu-rally occurring, extended aging processes. This work provides and validates an accelerated method of synthesizing uranium-immobilized iron oxide nanoparticles for further mechanistic studies. High tem-perature oxide melt solution calorimetry measurements were performed to calculate the thermodynamic stability of uranium-incorporated iron oxide nanoparticles. Increasing uranium content within hematite resulted in more positive formation enthalpies. Standard formation enthalpies of UxFe(2-2x)O(3) were as high as 76.88 +/- 2.83 kJ/mol relative to their binary oxides, or -764.04 +/- 3.74 kJ/mol relative to their con-stituent elements, at x = 0.037. Data on the thermodynamic stability of uranium retention pathways may assist in predicting waste uranyl remobilization, as well as in developing more effective methods to retain uranium captured from aqueous environments. (C) 2021 Elsevier B.V. All rights reserved.