(7gg) Investigation and Implementation of Adsorption Models in Nuclear Energy

Authors: 
Ladshaw, A., Georgia Institute of Technology
Yiacoumi, S., Georgia Institute of Technology
Tsouris, C., Oak Ridge National Laboratory
Adsorption is a complex physical-chemical process by which molecules are attached to surfaces of solid particles. The type of adsorption that occurs may often depend on the media the phenomenon is occurring in, making the design of models for various adsorption systems an arduous task. Regardless of the media, however, the basic mechanisms of the adsorption process are the same. Therefore, a plausible approach to the development of adsorption models in different systems would be to design a generalized mathematical framework with all the necessary methods built in that will be used as a platform to develop system-specific adsorption models. In this work, the investigation and development of such a structure will be discussed and a host of system-specific adsorption models that have been developed on top of that framework will be detailed. The problems of interest are all related to nuclear energy and specifically the availability of uranium in the Nuclear Fuel Cycle via recycling spent uranium fuel rods and capturing uranium fuel from seawater. In recycling spent uranium, the reprocessing procedure produces numerous gas pollutants that must be removed from the off-gases before emission to the atmosphere. To facilitate the design of that capture system, adsorption models have been developed to predict isothermal equilibria of complex gas mixtures and to quantify the rates of adsorption for various adsorbent materials. For recovering uranium from seawater, two different models were produced: (i) a predictive, multi-ligand adsorption model to incorporate effects of pH, ionic strength, and competing metals and (ii) an analytical model for quantifying the impact of current velocity on the mass transfer limitations of braided fiber adsorbents. The culmination of these adsorption models will provide tools for scientists and engineers to better understand adsorption phenomena in the applications of interest and subsequently design and/or control the necessary capture systems at both the front and back ends of the Nuclear Fuel Cycle.

Research Interests:

Throughout my academic career, my research focus has been on the development and application of adsorption models for engineered and natural systems. In environmental sciences and engineering, it is not very common to have researchers who have focused primarily on modeling and mathematics as opposed to experimentation. However, I felt drawn to modeling as I have a natural affinity towards mathematics, especially the applications of mathematics to solving complex problems. In addition, having expertise in computer modeling and simulation is becoming increasingly important today as computers have become cheaper and faster than ever before.

Part of my future plan includes exploring new and innovative numerical modeling techniques that I have learned over these last several years in graduate school. The current modeling framework I have developed is excellent for large, sparse systems of equations, but could be improved further by incorporating Message Passing Interface (MPI) aware/safe code. This would then allow the framework to be scaled onto massively parallel computing architectures. In addition, I would also like to expand some preliminary work I have done in developing my own types of numerical solvers, such as a recursive Krylov method for sparse linear systems and a variational polynomial technique for partial differential equations.

My work in the design and implementation of adsorption process models has given me a breadth of knowledge in both air and water quality engineering, as well as numerical methods and computer simulation. Beyond the nuclear fuel cycle application, the modeling framework for adsorption has broad functionality in numerous other areas of environmental science and engineering including ground water remediation, carbon capture, and activated carbon filtration. It is my hope to continue to add to this modeling framework while pursuing new research opportunities.

Teaching Interests:

Teaching environmental science and engineering has been a passion of mine ever since I started college. I have always enjoyed working with other students and have often taken the lead on many group activities, as I was extremely motivated to learn and to help others around me learn. As a teacher, I would work to communicate my passion of environmental science and engineering to my students and strive to instill in them the same motivation for learning as I had when I was a student.

A healthy balance between research and teaching is necessary to foster a successful career in academia. However, these two areas need not be treated entirely as separate entities. It has been my experience that the best college professors are the ones who can successfully connect classroom concepts to real world challenges. By bringing research concepts and problems into the course material, one can help foster interest and engagement in the subject by demonstrating its applicability outside of the classroom. I plan to regularly apply my own research in lectures whenever possible and would even want to design special homeworks or assignments based on problem solving exercises from research.

One course that I would be especially motivatd to teach is a numerical methods course with an emphasis on applying/designing algorithms to solving complex problems in environmental science. In today’s modern computing world, there is increasing demand for the use of computer simulations to predict how different environmental and engineered systems will behave under different stimuli or scenarios. For this course, I want to introduce students to the various numerical techniques developed for solving these very complex, coupled systems, then have them apply that knowledge through coding exercises in a computer language like C++ or Matlab.