CAREER: Rare Earth Elements Recovery from Nanoporous Ion-Adsorption Clays using Seawater

稀土元素（REEs）是几乎所有清洁能源技术所需的材料，可以实现能源系统的脱碳。例如，镝是一种重稀土元素，用于制造风力涡轮机和电动汽车中的永磁体。重稀土元素如镝是最稀缺和最有价值的，它们主要来自纳米多孔离子吸附粘土矿床。目前从离子吸附粘土矿床中回收稀土元素的做法缺乏对回收率的控制，需要大量的化学溶液，称为沥滤液，这可能会导致严重的生态影响。环境友好的渗滤液，如海水是一个有前途的替代回收稀土离子吸附粘土矿床直接。然而，这些沥滤液如何与纳米多孔粘土矿床相互作用，从根本上控制稀土回收规模的了解有限。该项目将探索控制纳米承压水-空气-粘土界面多相运输和吸附的微观和纳米尺度机制，并将建立关系，以告知从离子吸附粘土矿床中回收升级的环境友好型稀土元素。所获得的基础知识也可以翻译，以帮助理解环境修复，电池科学和分离科学中的类似过程。该研究整合了教育和推广工作，以促进早期接触科学，通过开发一个互动的虚拟现实应用程序，在那里孩子们采取探索性的“游乐设施”通过一个多孔的world.The CAREER项目的目标是发展的多相反应传输现象的基本理解，控制稀土回收不饱和，松散的纳米多孔粘土使用海水作为环境友好的渗滤液。将开发一套新的微流体和纳米流体成像平台，首次实现纳米多孔介质内原位流体-固体相互作用的操作可视化。微观和纳米尺度孔隙级可视化的定量处理，包括润湿反应表面作为水化学的函数和由于纳米级电动现象而增强的反应性运输，将被编织成孔隙集合参数，例如相对渗透率和有效反应动力学，使用降阶模型来预测和设计环境友好和有效的原地浸出方法。移动的水-空气-粘土界面的光学和电子显微照片序列将被构建成一个互动的虚拟现实世界，让学童参与STEM学习活动。通过感官游戏，学习模块将建立与纳米约束多孔介质中多相反应运输相关的科学原理的基本直观理解。该应用程序将免费下载到移动的手机上，应用程序的开发将使当地的K-12教室参与迭代反馈。K-12级别的科学教师将参加为期一周的专业发展计划，重点是通过多孔介质的多相流，以帮助将教育模块整合到他们的教室中。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Rare earth elements (REEs) are required materials in nearly all clean energy technologies that will enable the decarbonization of energy systems. For example, dysprosium is a heavy REE that is used to make the permanent magnets found in wind turbines and electric vehicles. Heavy REEs like dysprosium are the scarcest and most valuable, and they are produced predominantly from nanoporous ion-adsorption clay deposits. Current practices for REEs recovery from ion-adsorption clay deposits lack control over recovery rates and require enormous volumes of chemical solutions called leachates, which can result in severe ecological impacts. Environmentally-benign leachates such as seawater are a promising alternative for recovering REEs directly from ion-adsorption clay deposits. However, there is limited understanding of how these leachates interact with the nanoporous clay deposits to fundamentally control REEs recovery at scale. This project will explore the micro- and nano-scale mechanisms that control multiphase transport and sorption at nanoconfined water-air-clay interfaces, and relationships will be developed to inform upscaled, environmentally-benign REEs recovery from ion-adsorption clay deposits. The fundamental knowledge gained can also be translated to help understand similar processes in environmental remediation, battery science, and separations science. The research integrates education and outreach efforts to promote early-age exposure to science through the development of an interactive virtual reality application, where children take exploratory “rides” through a porous world.The goal of this CAREER project is to develop a fundamental understanding of the multiphase reactive transport phenomena that control REEs recovery from unsaturated, unconsolidated nanoporous clays using seawater as environmentally-benign leachate. A suite of novel micro- and nanofluidic imaging platforms will be developed that enable, for the first time, operando visualization of in situ fluid-solid interactions within nanoporous media. Quantitative treatment of micro- and nano-scale pore-level visualizations, including wetted reaction surfaces as a function of aqueous chemistry and the enhancement of reactive transport due to nanoscale electrokinetic phenomena, will be woven into pore-ensemble parameters, such as relative permeability and effective reaction kinetics, using reduced-order models to predict and design environmentally-benign and effective in situ leaching approaches. Optical and electron micrograph sequences of moving water-air-clay interfaces will be built into an interactive virtual reality world to engage school children in STEM learning activities. Through sensory play, the learning modules will build a basic intuitive understanding of the scientific principles associated with multiphase reactive transport in nanoconfined porous media. The application will be downloadable onto mobile phones at no cost, and application development will engage local K-12 classrooms in iterative feedback. Science teachers at the K-12 level will participate in a week-long professional development program focused on multiphase flow through porous media to assist in integrating the educational modules in their classrooms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.