Ding Rongrong, Guida Carolina, Pearce Carolyn I, Arenholz Elke, Grenèche Jean-Marc, Gloter Alexandre, Scheinost Andreas C, Kvashnina Kristina O, Wang Kaifeng, Fernandez-Martinez Alejandro, Mu Yang, Rosso Kevin M, Charlet Laurent
Institute of Earth Science (ISTerre), Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, F-38000 Grenoble, France.
CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China.
Sci Adv. 2025 May 16;11(20):eadq3650. doi: 10.1126/sciadv.adq3650.
Understanding the redox transitions that control rhenium geochemistry is central to paleoredox and geochronology studies, as well as predicting the fate of chemically similar hazardous oxyanions in the environment such as pertechnetate. However, detailed mechanistic information regarding rhenium redox transitions in anoxic systems is scarce. Here, we performed a comprehensive laboratory study of rhenium redox transitions on variably oxidized magnetite nanoparticle surfaces. Through high-end spectroscopic and microscopic tools, we propose an abiotic transition pathway in which aqueous iron(II) ions in the presence of pure or preoxidized magnetite serve as an electron source to reduce rhenium(VII) to individual rhenium(IV) atoms or small polynuclear species on nanoparticle surfaces. Notably, iron(II) ions recharged preoxidized magnetite nanoparticles exhibit a maghemite core and a magnetite shell, challenging the traditional core-shell magnetite-maghemite model. This study provides a fundamental understanding of redox processes governing rhenium fate and transport in the environment and enables an improved basis for predicting its speciation in geochemical systems.
了解控制铼地球化学的氧化还原转变对于古氧化还原和地质年代学研究至关重要，同时对于预测环境中化学性质相似的有害含氧阴离子（如高锝酸盐）的归宿也很关键。然而，关于缺氧系统中铼氧化还原转变的详细机理信息却很匮乏。在此，我们对可变氧化态的磁铁矿纳米颗粒表面上的铼氧化还原转变进行了全面的实验室研究。通过高端光谱和显微镜工具，我们提出了一种非生物转变途径，即在纯磁铁矿或预氧化磁铁矿存在的情况下，水合亚铁离子作为电子源，将铼（VII）还原为纳米颗粒表面上的单个铼（IV）原子或小的多核物种。值得注意的是，重新充电的预氧化磁铁矿纳米颗粒中的亚铁离子呈现出磁赤铁矿核心和磁铁矿外壳，这对传统的核壳磁铁矿 - 磁赤铁矿模型提出了挑战。这项研究为控制铼在环境中的归宿和迁移的氧化还原过程提供了基本认识，并为预测其在地球化学系统中的形态提供了更好的基础。
