Aluminoborosilicate Waste Glass Dissolution under Alkaline Conditions at 40°C: Implications for a Chemical Affinity-Based Rate Equation
Aluminoborosilicate Waste Glass Dissolution under Alkaline Conditions at 40°C: Implications for a Chemical Affinity-Based Rate Equation
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40°C 碱性条件下铝硼硅酸盐废玻璃溶解：对基于化学亲和力的速率方程的影响
DOI：
10.1071/en07058
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发表时间：
2008
影响因子：
4.3
通讯作者：
Elsa A. Rodriguez
中科院分区：
文献类型：
--
作者：
E. Pierce;E. L. Richards;A. Davis;L. R. Reed;Elsa A. Rodriguez
环境背景。核材料的生产产生了大量的高放射性废物，需要以使其在数百万年内不构成危险的方式加以处置，直到放射性衰减。为完成这项艰巨的任务，正在考虑的工艺是将废物控制在玻璃中。尽管对古代和天然玻璃的研究表明，玻璃的风化是缓慢的，但人们正在进行实验，以确定这种材料对自然环境的影响，并试图预测其长期行为。本文件简要讨论了为实施这一进程正在考虑的三种模式，以及似乎最有希望的一种模式。抽象。用铝硼硅酸盐废玻璃进行单程流通实验，以评估溶液组成的变化如何影响在40°C和pH（23°C）= 9.0下的溶解速率（r）。在这些实验中使用的三种原型低活性废物（LAW）玻璃，LAWE-1A、-95A和290 A，涵盖了候选固定低活性废物（ILAW）玻璃的预期处理组成的广泛范围。结果表明，在低流速（q）下，Al、B、Na和Si不一致地释放到样品表面积（S），单位为（m s-1），（log 10（q/S）-7.9）。溶出速率从log 10（q/S）≥-9.3增加到-8.0，然后在log 10（q/S）>-7.9时保持恒定。基于B释放的前向（最大）溶出速率相同，与玻璃组成无关，溶出速率在彼此的实验误差范围内，这一点很明显（r1 A = 0.0301 ± 0.0153 g m-2天-1，r95 A = 0.0248 ± 0.0125 g m-2天-1，r290 A = 0.0389 ± 0.0197 g m-2天-1）。结果还表明，随着SiO2（aq）活性的增加，玻璃的溶解速率降低到剩余速率。根据这些结果预测的假平衡常数Kg（log 10（Kg）= -3.7）略低于40°C时玉髓的K（log 10（K）= -3.48）。最后，这些结果支持使用的化学亲和力为基础的速率定律来描述玻璃溶解作为溶液组合物的函数。
Environmental context. The production of nuclear materials has generated a very large amount of highly radioactive wastes that need to be disposed of in a manner that will keep them from posing a danger for millions of years until the radioactivity decays. The process being considered for this daunting task is to contain the wastes in glass. Although studies with ancient and natural glass suggest the weathering of glass is slow, experiments are being conducted to determine the impact of this material on the natural environment and attempt to predict its long-term behaviour. The present paper briefly discusses three models that are being considered for implementing this process and the one that appears to hold the most promise. Abstract. Single-pass flow-through experiments were conducted with aluminoborosilicate waste glasses to evaluate how changes in solution composition affect the dissolution rate (r) at 40°C and pH (23°C) = 9.0. The three prototypic low-activity waste (LAW) glasses, LAWE-1A, -95A and -290A, used in these experiments span a wide range covering the expected processing composition of candidate immobilised low-activity waste (ILAW) glasses. Results suggest incongruent release of Al, B, Na, and Si at low flow-rate (q) to sample surface area (S), in units of (m s–1), (log10(q/S) –7.9). Dissolution rates increase from log10(q/S) ≈ –9.3 to –8.0 and then become constant at log10(q/S) > –7.9. Forward (maximum) dissolution rates, based on B release, are the same irrespective of glass composition, evident by the dissolution rates being within the experimental error of one another (r1A = 0.0301 ± 0.0153 g m–2 day–1, r95A = 0.0248 ± 0.0125 g m–2 day–1, and r290A = 0.0389 ± 0.0197 g m–2 day–1). The results also illustrate that as the activity of SiO2(aq) increases, the rate of glass dissolution decreases to a residual rate. The pseudo-equilibrium constant, Kg, (log10(Kg) = –3.7) predicted with these results is slightly lower than the K for chalcedony (log10(K) = –3.48) at 40°C. Finally, these results support the use of a chemical affinity-based rate law to describe glass dissolution as a function of solution composition.