Vejar Manuel R, Zengotita Frances E, Weiss Stephan, Azzam Salim Shams Aldin, Huittinen Nina, Beutner Sabrina, Bazarkina Elena F, Amidani Lucia, Kvashnina Kristina O, Hixon Amy E
Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, Dresden 01328, Germany.
Environ Sci Technol. 2025 Jun 17;59(23):11756-11766. doi: 10.1021/acs.est.4c13899. Epub 2025 Jun 3.
To facilitate the continued use of commercial nuclear power and address environmental contamination, it is essential to understand the fate and transport of plutonium (Pu) in (sub)surface environments. Current geochemical models do not account for complexity in mineral assemblages, such as metal substitution or the role of nanoscale crystallite sizes. In this work, we studied mineralogically complex systems where Pu(V) was the sorbate and Al-substituted or nanoscale iron (oxyhydr)oxides were the sorbents. Using M-edge and L-edge high-energy resolution fluorescence detection X-ray absorption near-edge structure (HERFD-XANES) spectroscopy, we probed the electronic configuration of Pu, quantified the extent of Pu surface-mediated reduction, and explored Pu speciation. Our results indicate that nanoscale iron oxides exert a greater degree of control over the redox behavior of Pu than Al-substituted iron (oxyhydr)oxides under circumneutral pH and oxic conditions. This is due to the dependence of Pu surface-mediated reduction on an initial sorption step, which is greater with the increased specific surface area and reactivity of nanoscale crystallites.
为促进商业核电的持续使用并解决环境污染问题，了解钚（Pu）在（次）表层环境中的归宿和迁移至关重要。当前的地球化学模型未考虑矿物组合的复杂性，例如金属替代或纳米级微晶尺寸的作用。在这项工作中，我们研究了矿物学复杂的系统，其中Pu（V）为吸附质，铝取代的或纳米级铁（氢）氧化物为吸附剂。利用M边和L边高能分辨率荧光检测X射线吸收近边结构（HERFD-XANES）光谱，我们探测了Pu的电子构型，量化了Pu表面介导还原的程度，并探索了Pu的形态。我们的结果表明，在中性pH和有氧条件下，纳米级铁氧化物对Pu氧化还原行为的控制程度比铝取代的铁（氢）氧化物更大。这是由于Pu表面介导还原对初始吸附步骤的依赖性，随着纳米微晶比表面积和反应性的增加，这种依赖性更强。
