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

稀土元素（ree）是几乎所有清洁能源技术所需的材料，将使能源系统脱碳。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。重稀土如镝是最稀有和最有价值的，它们主要产自纳米孔离子吸附粘土矿床。目前从离子吸附粘土沉积物中回收稀土的做法缺乏对回收率的控制，并且需要大量被称为渗滤液的化学溶液，这可能导致严重的生态影响。对环境无害的渗滤液，如海水，是直接从离子吸附粘土沉积物中回收稀土的一个有前途的选择。然而，对于这些渗滤液如何与纳米多孔粘土沉积物相互作用，从而从根本上控制稀土的大规模回收，人们的理解有限。该项目将探索控制纳米水-气-粘土界面多相传输和吸附的微观和纳米尺度机制，并将发展关系，为从离子吸附粘土矿床中大规模、环保地回收稀土提供信息。所获得的基础知识也可以转化为帮助理解环境修复、电池科学和分离科学中的类似过程。这项研究将教育和推广工作结合起来，通过开发一个交互式虚拟现实应用程序，促进幼儿接触科学，让孩子们在一个多孔的世界中进行探索。本CAREER项目的目标是发展对多相反应传输现象的基本理解，该现象控制着利用海水作为无害环境的渗滤液从非饱和、松散的纳米多孔粘土中回收稀土。将开发一套新型微流体和纳米流体成像平台，首次实现纳米多孔介质中流体-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，包括湿润的反应表面作为水化学的功能，以及由于纳米尺度电动力学现象而增强的反应运输，将被编织成孔隙集合参数，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位浸出方法。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到一个交互式虚拟现实世界中，以吸引学童参与STEM学习活动。通过感官游戏，学习模块将建立对纳米多孔介质中多相反应输运相关科学原理的基本直观理解。该应用程序将免费下载到手机上，应用程序的开发将与当地K-12教室进行反复反馈。K-12级的科学教师将参加为期一周的专业发展项目，重点关注多孔介质中的多相流，以帮助他们将教育模块整合到课堂中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.