Begg James D, Zavarin Mavrik, Tumey Scott J, Kersting Annie B
Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.
J Environ Radioact. 2015 Mar;141:106-14. doi: 10.1016/j.jenvrad.2014.12.002. Epub 2015 Jan 6.
Understanding plutonium (Pu) sorption to, and desorption from, mineral phases is key to understanding its subsurface transport. In this work we study Pu(IV) sorption to industrial grade FEBEX bentonite over the concentration range 10(-7)-10(-16) M to determine if sorption at typical environmental concentrations (≤10(-12) M) is the same as sorption at Pu concentrations used in most laboratory experiments (10(-7)-10(-11) M). Pu(IV) sorption was broadly linear over the 10(-7)-10(-16) M concentration range during the 120 d experimental period; however, it took up to 100 d to reach sorption equilibrium. At concentrations ≥10(-8) M, sorption was likely affected by additional Pu(IV) precipitation/polymerization reactions. The extent of sorption was similar to that previously reported for Pu(IV) sorption to SWy-1 Na-montmorillonite over a narrower range of Pu concentrations (10(-11)-10(-7) M). Sorption experiments with FEBEX bentonite and Pu(V) were also performed across a concentration range of 10(-11)-10(-7) M and over a 10 month period which allowed us to estimate the slow apparent rates of Pu(V) reduction on a smectite-rich clay. Finally, a flow cell experiment with Pu(IV) loaded on FEBEX bentonite demonstrated continued desorption of Pu over a 12 day flow period. Comparison with a desorption experiment performed with SWy-1 montmorillonite showed a strong similarity and suggested the importance of montorillonite phases in controlling Pu sorption/desorption reactions on FEBEX bentonite.
了解钚（Pu）在矿物相上的吸附和解吸对于理解其在地下的迁移至关重要。在这项工作中，我们研究了Pu(IV)在工业级FEBEX膨润土上10(-7)-10(-16) M浓度范围内的吸附情况，以确定在典型环境浓度（≤10(-12) M）下的吸附是否与大多数实验室实验中使用的Pu浓度（10(-7)-10(-11) M）下的吸附相同。在120天的实验期内，Pu(IV)在10(-7)-10(-16) M浓度范围内的吸附大致呈线性；然而，达到吸附平衡需要长达100天的时间。在浓度≥10(-8) M时，吸附可能受到额外的Pu(IV)沉淀/聚合反应的影响。吸附程度与先前报道的Pu(IV)在较窄的Pu浓度范围（10(-11)-10(-7) M）内吸附到SWy-1钠蒙脱石上的情况相似。还在10(-11)-10(-7) M的浓度范围内对FEBEX膨润土和Pu(V)进行了为期10个月的吸附实验，这使我们能够估计富含蒙脱石的粘土上Pu(V)还原的缓慢表观速率。最后，用负载有Pu(IV)的FEBEX膨润土进行的流动池实验表明，在12天的流动期内Pu持续解吸。与用SWy-1蒙脱石进行的解吸实验相比，显示出很强的相似性，并表明蒙脱石相对控制FEBEX膨润土上的Pu吸附/解吸反应很重要。
