Describe the work you will be presenting for your Research Café.

Ion exchange is a key technique for the separation, purification and concentration of cations and anions that may have commercial value or are hazardous. In this class of materials the actinides present particular challenges, such as the recovery of actinides and fission products found in irradiated nuclear fuels. Important parameters that one can tune for successful ion-exchange separations include the chemical and physical properties of the ion exchanger, the chemical composition of feed and eluting solutions, oxidation state, temperature, and pressure.  A key metric in ion-exchange separations is the inherent selectivity of an ion-exchanger for a particular sorbate. This is particularly true when the feed solution is comprised of multiple chemically similar ions.

We propose a systematic study of the titanium-based exchangers, such as sodium titanates, which are known to selectively separate strontium actinide ions from high ionic-strength solutions, in order to determine the mechanism of selectivity. Because these are nano-crystalline materials we will employ high energy x-ray scattering and the Pair Distribution Function to gain insight into the structures of these materials in their native and ion-exchanged forms.

Are there any other projects you are currently working on?

Naturally occurring nano-minerals dominate important chemical reactions in the environment - clays and iron/aluminum oxide-hydroxides are amongst the most critical vectors of nutrient and contaminant exchange in soils; deposition and transportation of solutions containing amorphous/nano-carbonates and phosphates dominate the growth of exo- and endo-skeletons in organisms.  Very little is known about the atomic arrangements in these materials and how these evolve with time, concentration and temperature. The group has made progress with one of these systems - iron oxide hydroxide. Along with former graduate student, Marc Michel, we published our most highly cited paper in Science and received the President’s Award for Doctoral Research. What that work lacked, however, was the time aspect: How does the nano-particle evolve and how is this reflected in changing atomic arrangements? To attack these problems requires a whole new way of thinking and the development of new experimental protocols.

We collaborate with Dr. Richard (Rick) Weber of Materials Development Inc. (MDI) who is an expert in the design, construction and commissioning of ultrasonic levitators. These devices allow us to levitate a droplet solutions from which nano-particles precipitate. Using high energy x-ray beams at the Argonne synchrotron we can then obtain the scattering data that will allow us to propose models for how the solutions and the nano-particles precipitating from them evolve. Since the solution is suspended in midair, it is not in a container - it is the interference from the container scattering that has made these sorts of experiments difficult in the past. We have the opportunity to be in "on the ground floor" as ultrasonic levitation is interfaced to the synchrotron beam.   

What was the deciding factor for you to come to Stony Brook for your graduate studies?

There were several factors that contributed to my decision to pursue my doctoral degree at Stony Brook. SBU is ranked as the top 1% universities worldwide and the Geosciences Department was recommended by my advisors at CUNY Brooklyn College. SBU also offered me a very enticing financial package; since I was offered a Turner Fellowship, I would be funded for at least five years. Lastly, and most importantly, was the Center for Inclusive Education. I was worried about the diversity amongst SBU graduate students, but the CIE community provided a safe space to interact with other minority students. They became my closest colleagues, friends and mentors.

What are your future goals?

My future goals are to complete my doctoral degree in Geosciences at SBU and then pursue a research career in academia. I am also open to working in Industry or DOE national labs where I can pursue nanomaterials research.

What do you enjoy most about research?

I enjoy the autonomy and the opportunity to pursue lifelong learning in a flexible environment. As long as I can continue to improve my craft as a scientist and an educator, I will be content.