Blog by Holly Rudel, Yale University
Over the past week, I had the opportunity to travel to Arizona State University. For the past five years, I have collaborated with Dr. Chris Muhich’s lab and Dr. Paul Westerhoff’s lab on designing selective adsorbents for drinking water treatment. This was my first opportunity to go to ASU and meet Srishti Gupta (Muhich lab) and Emily Briese (Westerhoff lab) and learn more about their work.
With Srishti, I was able to learn more about how she performs her DFT calculations. She and I have worked closely because we are curious what fundamental mechanisms are at play to explain my experimental work testing the selectivity of hematite nanostructures in the adsorption of As and Se. With Srishti, I was able to see how she sets up her “jobs”, and what process she utilizes to model my experimental system. To do this, she finds the most relaxed surface structure of hematite, add a water network, introduce the oxoanion of interest, and finally she can calculate the energetics of binding in a variety of different configurations.
Our experimental and computational results are in good agreement in terms of which oxoanions bind the strongest to hematite surfaces, and how the exposed surface facet can result in different energetics of adsorption. I was able to discuss with Srishti and Dr. Muhich, and this exciting alignment means that we expect to publish at least three collaborative papers based on these results over the next few months. Additionally, I was able to support Srishti as she successfully presented her thesis defense. Seeing her computational work, both based on the project we have worked on together and on a different NEWT project she has worked on, was a great opportunity to learn how to concisely and thoroughly present thesis research, as I will be defending my own thesis work in the next few months.
With Emily, we did an extensive tutorial of how she performs her surface complexation modelling (SCM) using Visual Minteq. She showed me how she is able to determine the governing surface complexation equations to consider, and how she can change experimental parameters of the sorbent (surface area, surface site binding) and solution (ionic strength, pH) to predict experimental sorption isotherms. We discussed how she could utilize her modelling to predict adsorption of my faceted hematite nanostructures and what experimental information I would need to collect in order for the model to be most accurate. Additionally, Emily has been working to embed my nanomaterials on optical fibers and test in batch systems, so I was able to go into lab and see this process for myself. We discussed the challenges with affixing the materials, as well as what sorption tests she could perform in order to compare with my own batch experiments. Based on these two projects, we discussed that we expect to publish at least two collaborative papers.
Overall, the trip was successful because of the different techniques I got to learn and also the opportunity to discuss how our expertise could coalesce into rigorous, collaborative papers. I am excited to continue work with Emily and Srishti with a better understanding of how they conduct their research so that we can ultimately work together to design effective, selective sorbents for remediation of arsenic and selenium contamination in drinking water.