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Uranium Release from Acidic Weathered Hanford Sediments: Single-Pass Flow-Through and Column Experiments
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2017-09-21 00:00:00 , DOI: 10.1021/acs.est.7b03475
Guohui Wang 1 , Wooyong Um 1, 2 , Zheming Wang 1 , Estela Reinoso-Maset 3 , Nancy M. Washton 1 , Karl T. Mueller 1 , Nicolas Perdrial 4, 5 , Peggy A. O’Day 3 , Jon Chorover 4
Affiliation  

The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford’s cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4)·3H2O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K2(UO2)6O4(OH)6·7H2O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 × 10–12 mol g–1 s–1. In the absence of phosphate, uranium release was controlled by dissolution of uranium oxyhydroxide (compreignacite-type) mineral with a release rate of 1.05–2.42 × 10–10 mol g–1 s–1. The uranium mineralogy and release rates determined for both systems in this study support the development of accurate U-release models for the prediction of contaminant transport. These results suggest that phosphate minerals may be a good candidate for uranium remediation approaches at contaminated sites.

中文翻译:

酸性风化汉福德沉积物中的铀释放:单程通流和色谱柱实验

酸性放射性废物与沉积物的反应可引起矿物转化反应,进而控制污染物的归宿。在这里,使用台式规模的实验研究了含合成铀的酸溶液对沉积物的风化作用,以模拟汉福德婴儿床(华盛顿州汉福德)的废物处理条件。在酸性风化过程中,磷酸盐的存在对铀的矿物学影响很大,并且使用光谱和衍射法鉴定出了快速沉淀的结晶铀磷酸盐相(间苯二酚[K(UO 2)(PO 4)·3H 2 O])。基础的技术。在不含磷酸盐的系统中,氢氧化正铀矿物质,例如K-尖晶石[K 2(UO 26形成了O 4(OH)6 ·7H 2 O]。使用合成汉福德孔隙水进行的单程流经(SPFT)和柱浸实验表明,在酸性风化过程中,作为偏长石沉淀的铀被牢固地保留在沉积物中,平均释放速率为2.67×10 –12 mol g – 1–1。在没有磷酸盐的情况下,铀的释放是通过溶解氢氧化氢氧化铀(辉绿岩型)矿物来控制的,释放速率为1.05–2.42×10 –10 mol g –1 s –1。在本研究中,为这两个系统确定的铀矿物学和释放速率均支持精确的U释放模型的开发,以预测污染物的迁移。这些结果表明,磷酸盐矿物质可能是污染场地铀修复方法的良好候选者。
更新日期:2017-09-21
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