Field-Driven Ion Transport and Reactivity

Principal Investigator: Elias Nakouzi

Selective precipitation, a commonly used method in chemical separations, often faces limitations in applicability and efficiency due to the comparable solubilities of the ions of interest. This issue usually results in a mixture of desired and undesired products, necessitating additional energy- and chemical-intensive processing steps for complete separations. We propose an innovative approach that leverages the non-equilibrium coupling of ion transport and precipitation kinetics, offering a fresh perspective on chemical separations. By balancing the diffusion and nucleation kinetics of competing ions, our method will precipitate these species selectively and sequentially. Our objective is to facilitate the efficient separation of rare earth elements, transition metals, and other critical materials from unconventional domestic feedstocks. Our method avoids using membranes, ligands, toxic solvents, or other specialty chemicals, thereby enhancing its environmental sustainability and adaptability to different feedstocks. To achieve this goal, we will develop a fundamental understanding of how external fields influence (1) ion speciation and transport and (2) ion precipitation kinetics from multicomponent solutions. By investigating these essential aspects, we will revolutionize the field of chemical separations, making it more efficient, adaptable, and sustainable.

On-Line Monitoring of Complex Real-World Feedstocks

Principal Investigator: Amanda Lines

A practical challenge in separating critical materials from complex, real-world feedstocks is the quantitative monitoring and measurement of the targeted species throughout the separation process in a complicated and evolving matrix. We will devise and validate on-chip sensors that deliver in situ, real-time chemical composition analysis. This capability will elucidate the chemical and physical process efficiency of flow- and field-driven separations within model microfluidic devices. Such insights will illuminate the fundamental chemistry of separation processes and provide valuable data to inform the scale-up and deployment of far-from-equilibrium conditions to applied separations. We will employ optical spectroscopy techniques and chemical data science methods, such as chemometric analysis, to dissect intricate data streams. This approach will facilitate highly precise, real-time analyses and adaptive process control. Our strategy will enable novel advances in flow- and field-driven separations, potentially unveiling new chemical insights and enabling instantaneous process optimization.

Hydrothermal Field-Driven Separation of Rare Earth Elements

Principal Investigator: Xin Zhang

We will develop sustainable and efficient rare earth element separations based on electric and magnetic field-driven fractional crystallization at hydrothermal temperature and pressure conditions. We will investigate the evolution of rare earth element–anion complexes, clusters, and dense liquid phases to elucidate the tunability of fractional crystallization mechanisms and selectivity in nucleation and particle growth processes. We will obtain fundamental insights into rare earth element precipitation processes employing distinguishing in situ Raman, time-resolved, laser-induced fluorescence spectroscopy, and X-ray scattering techniques coupled with hydrothermal diamond-anvil cells or fused silica capillary capsules.

Validation of Non-Equilibrium Separations in Complex Feedstock

Principal Investigator: Chinmayee Subban

We will identify sustainable resources and develop separation processes for critical materials, primarily focusing on unconventional feedstocks, such as diverse brines, industrial effluents, and recycling streams. Existing mineral separation and extraction methods are often costly and chemical- and energy-intensive as they depend on specialty chemicals, membranes, and solvents. They are also typically not broadly applicable to a diverse range of feedstocks. We will validate the potential of selectively extracting critical minerals using external flow- and field-driven precipitation without specialty chemicals and verify the associated reduction in process costs and environmental impact. We have demonstrated such non-equilibrium field-driven separation of critical elements using small volumes of model solutions. We will understand the scalability of this approach and its relevance to industrial-scale mineral extraction. Because real-world feedstocks are chemically complex and variable, we will investigate process efficiency as a function of critical element concentration and feedstock composition using experiments, modeling, and online monitoring of both model synthetic and real-world feedstocks. Our results will inform scale-up, life cycle, and techno-economic analyses, thereby determining the commercial relevance of external field-driven separations.

Probing Field-Driven Ion Transport and Reactivity

Principal Investigator: Venky Prabhakaran

We will build minimally invasive operando experimental probes to directly visualize non-equilibrium processes emerging across relevant spatiotemporal scales in complex chemical mixtures with variable composition under liquid flow and applied electric and magnetic fields. These novel operando spectroscopy and microscopy tools will be used to establish causality between transport- and field-driven ion concentrations and measure (1) selective concentration gradients (i.e., ions, ion pairs, clusters, nucleates) across liquid–liquid interfaces and (2) the evolution kinetics of localized domains consisting of targeted ions (i.e., enrichment zones) near interfaces to enable selective precipitation reactions in complex aqueous solutions for non-equilibrium separations.

Modeling Specific Ion Responses to Electromagnetic Fields Across Fluid Domains

Principal Investigator: Maria Sushko

We will resolve the effect of coupled magnetic and electric fields on ion transport, speciation, and crystallization to facilitate separations from multicomponent mixtures. We will use a novel quantum chemistry approach within a many-body expansion formalism and ab initio molecular dynamics simulations to calculate the intrinsic properties of solvated ions, such as their charge density, excess polarizability, and magnetic susceptibility, to predict ion-specific responses to external fields. We will couple the data within a multiphysics approach that includes only elementary processes capable of affecting ion behavior and is sufficiently computationally efficient to encompass all solution species with realistic densities in cubic micron volumes. This approach will enable us to understand how the effects of hydrodynamic, magnetic, and electric fields drive ion transport and accumulation in targeted locations. We will test the hypothesis that local magnetic forces facilitate ion accumulation through positive feedback between field-induced concentration gradients and the formation of ion-specific magnetic domains and explore this effect as a driving force for ion-specific accumulation and precipitation from complex mixtures. The new theoretical framework will be an efficient capability for predicting electromagnetic field and flow conditions for efficient separations of critical materials from complex mixtures.

Theoretical Approaches for Far-from-Equilibrium and Non-Steady-State Conditions 

Principal Investigator: Hadi Dinpajooh

We will explore how inhomogeneous magnetic fields influence the motion of ions and solvent molecules, forming unique micro/nanodomains with distinct structural and dynamic properties. By leveraging these magnetic fields under far-from-equilibrium conditions, we will selectively separate correlated liquid domains and ions based on their magnetic properties. We will understand the dynamic evolution of these domains by developing accurate theoretical models and frameworks using new computational algorithms. The goal is to produce quantitative descriptions of micro/nanoscale interactions, critical for improving field-driven separation processes through magnetophoresis.

Probing External Field Effects on Rare Earth Element Separations at Liquid/Liquid Interfaces

Principal Investigator: Mavis Boamah

Emerging renewable energy technologies demand a sustainable and reliable supply of critical materials and rare earth elements (REEs). However, selective separation of REEs is challenging due to their similar physical and chemical properties. We will obtain a molecular-level understanding of non-equilibrium processes in liquid/liquid separations by developing an externally applied field vibrational sum frequency generation spectroscopy capability. By probing the effects of external fields at liquid interfaces, we will identify precursor species, changes in interfacial charge, and hydration states before precipitation. Manipulating interfacial potential based on pH, ionic strength, concentration, and applied external fields will allow us to control REE precipitation at aqueous interfaces. The molecular-level insights gained will enable us to better direct, predict, and control interface-driven liquid/liquid extraction of lanthanides and critical materials under flow conditions relevant for mineral processing and recycling.

Electrochemical Separation and Recovery of Critical Metals

Principal Investigator: Dan-Thien Nguyen; Co-principal Investigator: Ajay Karakoti

We will develop a flow-assisted direct alloy-to-metals (A2M) recovery process to enable energy-efficient recycling of end-of-life electronics and permanent magnets. The A2M approach seamlessly integrates electrochemical separation and electroplating into a single module operating at room temperature, facilitating the direct recovery of critical metals from metallic components of end-of-life products with high energy efficiency in an environmentally friendly manner. The system’s modular architecture will support continuous feedstock and chemical flow, facilitating integration into autonomous facilities. Our design will reduce operational costs, enhance atom and energy efficiency, and offer high customization based on feedstock composition.

Control and Measure Collective Ion Transport Under Inhomogeneous Electric and Magnetic Fields with Fluid Force Microscopy

Principal Investigator: Shuai Zhang

We will investigate non-equilibrium ion transport and nucleation driven by inhomogeneous electric and magnetic fields using a newly developed, noninvasive force mapping approach with nanometer-scale spatial and microsecond temporal resolution. This innovative method will bridge knowledge gaps in understanding how external fields influence interactions between critical material ions, enabling selective transport and precipitation. In operando, we will quantitatively measure the electrostatic and magnetic forces exerted on nanodroplets of critical minerals such as neodymium, dysprosium, and cobalt. These minerals are predicted to transport and selectively crystallize in laminar co-flow-based separations. Additionally, we will contribute to the development of predictive models that describe collective ion motion and nucleation, incorporating the effects of solvation environments and ion speciation under external stimuli.

Technoeconomic Assessment of Critical Mineral Feedstocks and Recovery Technologies

Principal Investigator: Peter Valdez 

Economic feasibility is a key driver for selecting and improving new technologies during their development phase. We will use technoeconomic and life cycle assessment (TEA/LCA) to screen and select promising feedstock and technology combinations that cost-effectively recover critical minerals, creating sustainable and reliable domestic supply chains. As new concepts are being tested, our early-stage assessments will quantify their economic potential and benefits compared to existing industry standards. Once completed, TEA/LCA, alongside initial experiments and modeling, will inform economic constraints and guide researchers to more feasible and scalable technical solutions. TEA will also explore the nationwide impact of a particular domestic resource based on the volume, concentration, and value of critical minerals present in the feedstock. TEA will guide technology development by assessing the scalability of a particular technology to achieve high-throughput processing while achieving cost targets and maximizing energy and chemical efficiency.

Nanoscale Dynamics of Rare Earth Element Separation and Assembly in Magnetic Fields

Principal Investigator: Hyoju Park 

We will investigate the nanoscale pathways and spatiotemporal evolution of rare earth element (REE) precipitation and separation under the influence of magnetic fields. Using transmission electron microscopy, we will directly visualize the nanoscale dynamics of REEs, from solution structuring and nucleation to nanodomain formation, particle growth/assembly, and selective enrichment. We will capture REE structures along reaction pathways using plunge-freezing and cryogenic transmission electron microscopy to preserve their native states and generate spatiotemporal distribution maps of REE precipitates. This project will provide fundamental insights into the mechanisms governing magnetic field–driven REE separation, precipitation, and assembly into materials, enabling the design of innovative strategies for selective extraction and recovery of critical minerals.

Multiscale Modeling of Paramagnetic Ion Transport in External Fields

Principal Investigator: Pauline Simonnin 

We will develop a physics-based multiscale framework to predict how coupled magnetic and flow fields influence the transport, clustering, and selective enrichment of paramagnetic ions in complex mixed solutions. By extending nonequilibrium molecular dynamics models to include magnetic interactions, we will quantify how ion coordination and magnetic susceptibility control nanoscale structuring and macroscopic mobility. The resulting molecular descriptors—such as viscosity, diffusivity, and dielectric response—will be validated through complementary atomic force microscopy and X-ray scattering experiments and integrated into continuum-scale computational fluid dynamics models used for process design and scale-up. This integrated modeling approach will connect molecular-scale dynamics to macroscopic transport, providing a predictive tool for designing efficient field-driven separations of critical materials under nonequilibrium conditions.

Multiphysics Modeling to Predict, Accelerate, and Optimize Scalable Designs for Nonequilibrium Separations

Principal Investigator: Yucheng Fu

We will develop a multiphysics modeling framework to predict and optimize far-from-equilibrium separations of critical minerals from unconventional domestic feedstocks. Integrating hydrodynamics, nonuniform magnetic fields, ion transport, precipitation kinetics, and particle dynamics, the model will capture how localized field gradients and flow conditions drive selective ion migration as well as particle formation and transport. The framework will also enable geometry optimization of scalable reactors, such as Y-shaped co-flow devices, to maximize elemental selectivity and energy efficiency, providing valuable input for technoeconomic and life cycle assessments. By bridging theory and experiment, this computational fluid dynamics capability will establish quantitative design rules that accelerate separations research and advance the goal of feedstock-agnostic recovery of critical minerals and materials from diverse unconventional domestic feedstocks.