Energy storage, clean water, and cryopreservation were the subjects of research posters selected as award recipients from the School of Chemical, Biological, and Environmental Engineering at the College of Engineering’s 2018 Graduate Research Showcase held Feb. 8.
A panel of the school’s faculty members selected the top three posters out of a field of more than 30 presentations representing a diverse cross-section of research interests from each of the school’s three main disciplines.
In addition to the recognition of their mentors and peers, winning presenters were invited to attend the 2018 Oregon Stater Awards ceremony on Feb. 22 in Portland, where they had the opportunity to present their research to the College of Engineering’s industry partners and distinguished alumni.
Improving batteries for a clean-energy future
Lynza Sprowl, a fifth-year chemical engineering student in the lab of Líney Árnadóttir, took top honors for her poster discussing how charge state impacts battery life in lithium-ion cells. Sprowl says improving upon this technology will be essential to making a global transition to clean and renewable energy.
“A lot of people are looking at solar panels and wind turbines, and there have been a lot of successes there,” Sprowl said. “But battery technology is the bottleneck. We need better energy storage to supply power when the sun isn’t shining or the wind isn’t blowing.”
When a lithium-ion battery is being charged, energized electrons at the surface of the anode cause the battery’s electrolyte to break down, consuming lithium ions and creating a chemical barrier that slows lithium ion diffusion to the anode.
“When lithium ions can’t reach the anode, you can’t charge the battery fully,” she said. “As the barrier gets thicker, fewer lithium ions remain and the lithium ion diffusion gets slower, until it reaches a point where it stops. At this point the battery lifetime is up.”
Sprowl uses mathematical modeling, specifically something called density functional theory (DFT), to look at the fundamental interactions of how electrolyte breaks down under different conditions.
“With computational studies, you can break down different electrolyte additives, see what products they make, and figure out how those additives match up experimentally with what you think is going to give the best results.”
One of Sprowl’s findings is that it is two times more favorable for the electrolyte to break down when the battery is at a high charge state. And this has immediate, practical implications that anyone can use.
“Basically, if you leave your phone plugged in overnight and it’s at 100 percent charge state for several hours, you’re shortening your battery life,” she said. “So, once it hits 100, take it off the charger.”
Using bacteria to clean up toxic waste
Riley Murnane, a second-year environmental engineering master’s student working in the lab of Lewis Semprini, took second place for his poster discussing substrate selection for a type of microorganism that shows promise in cleaning up toxic waste spills.
Rhodococcus rhodochrous is a species of soil bacteria that produces enzymes capable of degrading dioxane, a persistent groundwater contaminant, through a process called aerobic co-metabolism.
“The co-metabolism requires a certain substrate to be present,” Murnane said. “And I’m looking at which food-grade, economically viable, and readily available substrates work best in our context for this specific microbe’s enzyme.”
Murnane’s research focuses on a group of aromatic, sweet-smelling compounds called esters as potential substrates.
“The ones we’re looking at are all FDA-approved as food additives,” Murnane said. “For example, we’re working with things like sec-butyl acetate and benzyl acetate, which are used in fruit flavorings because they smell like banana or green apple.”
These esters hydrolyze, or degrade in water, over time to form an alcohol and an organic acid. It’s these end products that are taken up by the microbes, which in turn produce the enzyme that enables co-metabolism to happen.
“The idea is to encapsulate the microorganisms and their food supply into little gel beads that can be pumped into the upper sandy layer of the aquifer to work over time,” Murnane said. “We want the ester to hydrolyze slowly to the substrate that the bugs will use, so that they will continue to metabolize pollutants as they diffuse from the denser, clay layer. So the half-lives of the materials we’re looking at range from 100 to 3,000 days.”
Advancing cryopreservation to the next level
Ross Warner, a third-year chemical engineering Ph.D. student working in the lab of Adam Higgins, was awarded third place for his poster concerning a cryopreservation project.
Cryopreservation involves introducing chemicals such as ethylene glycol, better known as antifreeze, into biological specimens to suppress the formation of ice crystals so they can be preserved at very low temperatures.
“Dr. Higgins has done a lot of work at the single-cell level,” Warner said. “We’re at the point now of taking that knowledge gained and trying to advance to the next level of biological complexity. So a lot of my work has been on the theoretical modeling of tissues and organs.”
A major problem with exposing cells to ethylene glycol is toxicity. This problem is accentuated in larger specimens, such as whole organs, Warner says, because their larger volume requires greater cooling time and exposure to higher concentrations of antifreeze.
“If we can model the transport of this given antifreeze into and out of the cell, we can get a grasp of the toxicity it’s imparting,” Warner said. “Through mathematical modeling, we can calculate a given percentage of cell death at different concentrations, temperatures, time of exposure, and so on, and compare that to acceptable tolerances. If we can obtain a model that predicts concentration as a function of space and time we can predict toxicity as a function of space and time.”
Mathematical modeling enables researchers to home in on the type of experiments needed, Warner says, conserving time and resources and accelerating the pace of progress in the field. The research has big implications in the long-term preservation of tissues and organs, which could revolutionize transplant surgery.
“The lifespan of donor organs outside of the body is typically measured in hours,” Warner said. “What if we could extend that to days or weeks? Right now we have a pretty good grasp of blood banks, but what if there were organ banks? We could potentially save a lot of lives.”