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Physical Sciences and Engineering

Heavy Element Chemistry and Separation Science

Insights into heavy element structural chemistries, both in solution and in the solid state, are informing fundamental behaviors relevant to inorganic, physical, and materials chemistries, as well as separations and environmental sciences.

Heavy Elements Chemistry

The Heavy Elements Group studies the fundamental chemistry of the actinide series of elements.  Of particular focus is the role of the 5f electrons in their chemistry and how they influence the structure and reactivity of these elements.  Synthetic chemistry, spectroscopy, and structural characterization in both the solution and the solid states are used as probes of structure, bonding and electronic speciation, with significant focus on the transuranium elements.  We are interested in identifying the periodic trends across the actinide series that inform our understanding of the role both the 5f and 6d orbitals have on their chemistry with the goal of relating the complex chemistry of the actinide elements to the larger periodic system.   

Separation Science

Our separation science efforts are largely focused on liquid-liquid extraction (LLE), the go-to technology for f-element separation and purification. Our research is centered on detailing the free-energy components that drive the non-thermal separations, with a specific emphasis on quantifying the entropic contributions. Underpinning our work is the hypothesis that an accurate description of structural correlations spanning multiple length scales, from the atomic to the mesoscale, is required to describe and predict these liquid separations. Our experimental efforts involve a multimodal approach to system characterization, including the determination of separations efficacy through standard, in house techniques such as distribution ratios using radiotracers and dynamic light scattering. Key to our assessment of structure are synchrotron measurements of local structure (XAFS, HEXS), techniques probing longer-range solution aggregates, (SAXS and XPCS) and molecular-scale liquid surface and interfacial studies (XR, RAXR). The overall program is built a telescoping approach to quantifying these phenomena that couples atomic and molecular scale chemistry with the structure, energetics and dynamics of larger mesoscopic hierarchical assemblies. The broader implications of our research portfolio extend from use-inspired syntheses to soft-matter chemistry to interfacial behavior of multivalent ions and are meant to inform discussions ranging from energy production to chemical waste processing and storage.


How Water and Ions Interact with Graphene Oxide Films

Membranes are useful for separating materials from solutions, and graphene oxide (GO) membranes might prove superior to those made from polymers because of their greater durability and mechanical strength, especially in applications such as removing radioactive elements from contaminated groundwater. Read more…



Scientists Gain Insight into Recycling Process for Nuclear and Electronic Waste

The Hawaii and Alaska of chemistry, lanthanides and actinides are the elements that are always shown separately from the main block on the periodic table. Although they are split up from the more mainstream elements, they are important metals for applications such as nuclear power and magnets used in wind turbines and electric cars. Read more…

The Element of Surprise

Chemical elements on the periodic table also have family resemblances that could provide predictive insight into the way elements interact, leading scientists to not-yet-imagined applications. 

In the case of one element, protactinium, chemical similarities produced by the configuration of its outermost electrons link two families of elements: the stable and well-known transition metals and the more exotic actinides. Read more…


Unique Interface and Unexpected Behavior Help Explain How Heavy Metals Act 

Refining platinum, plutonium, or certain other metals often depends on how the metal behaves at liquid interfaces. The challenge? Scientists have limited ways to analyze the details of liquid interfaces. Now, researchers described in significant detail how water molecules surround a platinum-based ion. Their description includes an unexpectedly complex structure that forms on the liquid’s surface. Read more…