Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates
Thermodynamics of uranyl minerals: Enthalpies of formation of uranyl oxide hydrates
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铀酰矿物的热力学：氧化铀酰水合物的形成焓
DOI：
10.2138/am.2006.1856
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发表时间：
2006
影响因子：
3.1
通讯作者：
P. Burns
中科院分区：
文献类型：
--
作者：
Karrie;K. Helean;A. Navrotsky;P. Burns
摘要 使用高温氧化物熔融溶液量热法测定了七种氧化铀酰水合物相和一种铀酸盐的形成焓：[(UO2)4O(OH)6](H2O)5，metaschoepite； β-UO2(OH)2; CaUO4; Ca(UO2)6O4(OH)6(H2O)8，贝克尔石； Ca(UO2)4O3(OH)4(H2O)2; Na(UO2)O(OH)，钾镁石； Na2(UO2)6O4(OH)6(H2O)7，钙镁石的钠类似物，和 Pb3(UO2)8O8(OH)6(H2O)2，钙镁石。每种化合物在 298 K 下的二元氧化物形成焓 ΔHf-ox 是根据各自滴溶液的焓 ΔHds 计算得出的。 298 K 时元素的标准生成焓 ΔH0f 为 -1791.0 ± 3.2、-1536.2 ± 2.8、-2002.0 ± 3.2、-11389.2 ± 13.5、-6653.1 ± 13.8、-1724.7 ± 5.1、-10936.4 ±分别为 14.5 和 -13163.2 ± 34.4 kJ/mol。这些值可用于探索氧化铀酰水合物在辅助化学系统中的稳定性，例如在铀污染环境中预期的系统。
Abstract The enthalpies of formation of seven uranyl oxide hydrate phases and one uranate have been determined using high-temperature oxide melt solution calorimetry: [(UO2)4O(OH)6](H2O)5, metaschoepite; β-UO2(OH)2; CaUO4; Ca(UO2)6O4(OH)6(H2O)8, becquerelite; Ca(UO2)4O3(OH)4(H2O)2; Na(UO2)O(OH), clarkeite; Na2(UO2)6O4(OH)6(H2O)7, the sodium analogue of compreignacite, and Pb3(UO2)8O8(OH)6(H2O)2, curite. The enthalpy of formation from the binary oxides, ΔHf-ox, at 298 K was calculated for each compound from the respective drop solution enthalpy, ΔHds. The standard enthalpies of formation from the elements, ΔH0f, at 298 K are -1791.0 ± 3.2, -1536.2 ± 2.8, -2002.0 ± 3.2, -11389.2 ± 13.5, -6653.1 ± 13.8, -1724.7 ± 5.1, -10936.4 ± 14.5, and -13163.2 ± 34.4 kJ/mol, respectively. These values are useful in exploring the stability of uranyl oxide hydrates in auxiliary chemical systems, such as those expected in U-contaminated environments.