Dissolution Study of Metatorbernite: Thermodynamic Properties and the Effect of pH and Phosphate
Dissolution Study of Metatorbernite: Thermodynamic Properties and the Effect of pH and Phosphate
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DOI：
10.1021/es101619f
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发表时间：
2010-10-01
影响因子：
11.4
通讯作者：
Felmy, Andrew R.
中科院分区：
文献类型：
--
作者：
Ilton, Eugene S.;Zachara, John M.;Felmy, Andrew R.
在美国华盛顿州汉福德300 A区域的浅包气带中，已发现了铀酰铜磷酸盐，即变水砷铜矿。因此，模拟由大气降水补给驱动的包气带孔隙水中U浓度的演变需要准确了解变斑铜矿的溶解度。以前确定的溶解度常数为metatorbernite的约束。在本贡献中，天然变水钠长石晶体的溶解进行了研究，在目标pH值2.5和3.0，使用硝酸和磷酸。从欠饱和和过饱和接近稳态。实验和计算得出的优选log K-sp = -28.0 +/-0.1显著不同于先前确定的值。此外，化学计量和非化学计量溶解作为pH值和磷酸盐水溶液浓度的函数进行观察。
The uranyl copper-phosphate, metatorbernite, has been identified in the shallow vadose zone of the 300 A area at the Hanford site, WA, USA. Consequently, modeling the evolution of U concentrations in vadose zone porewaters driven by meteoric water recharge requires accurate knowledge of metatorbernite solubility. Previous determinations of the solubility constant for metatorbernite were under constrained. In the present contribution, the dissolution of natural metatorbernite crystals was studied at target pH 2.5 and 3.0, using both nitric and phosphoric acid. Steady state was approached from under- and supersaturation. The experiments and calculations yielded a preferred log K-sp = -28.0 +/- 0.1 that is significantly different than previously determined values. Further, both stoichiometric and nonstoichiometric dissolution was observed as a function of pH and aqueous phosphate concentration.