Onur Apul, an assistant professor of environmental engineering at the University of Maine, will lead a NASA-supported $1.1 million multi-institutional investigation to determine whether nanobubbles can support space exploration, including the treatment of water on spaceships.

Through the Maine Space Grant Consortium, NASA’s Established Program to Stimulate Competitive Research (EPSCoR) awarded the project a grant of $753,750. It was matched with a cost-share contribution of $350,000 provided by participating institutions, which included UMaine, University of Southern Maine, and Arizona State University.

Nanobubbles are ultrafine pockets of oxygen, carbon dioxide, hydrogen, and other gases in liquids that are less than 100 nanometers in diameter. Apul says nanobubbles can be generated in liquids with simple instruments that cause liquids to oscillate and by other hydraulic, physicochemical and electrochemical methods. This results in mixtures known as biphasic liquids – those that take the form of both a liquid and a gas.

Apul says that due to their size, nanobubbles possess unique physicochemical properties that he believes can improve the efficiency of life support functions on spacecraft, especially water treatment and growth. algae to provide oxygen and nutrition to astronauts. Unlike ordinary bubbles that float on the surface of a liquid, nanobubbles can remain suspended there for hours, days, or even months. Apul says they also possess a large surface area and high reactivity, but are also malleable, making them ideal for chemical reactions. All of these aspects allow nanobubbles to provide reliable and accessible storage for various gases, which Apul says supports and reduces the energy cost of water treatment and other systems on earth and possibly in space.

To determine if nanobubbles can benefit life support systems beyond Earth’s atmosphere, Apul and his team need to ensure they can withstand micro- and weightlessness, as well as fluid conditions. in these environments. Their research will focus on nanobubbles of oxygen, hydrogen, nitrogen, ozone and other atmospheric gases. Additionally, they will assess the extent to which nanobubbles enhance mass transport of gases, which would increase the efficiency of water treatment systems and produce reactive oxygen species that could fuel algal growth.

The researchers will first generate their own nanobubbles in biphasic liquids with existing and new equipment at UMaine. They will then test their stability in a high-altitude balloon, which can travel up to 118,000 feet or more, thanks to UMaine’s high-altitude balloon program; a small research satellite called CubeSat, and in two rocket launches. blueShift Aerospace Inc. in Brunswick, Maine, will work with researchers on launches of the CubeSat, which will be called PINESAT2 and will be built at UMaine’s Department of Electrical and Computer Engineering’s WiSe-Net lab, as well as the two rockets launches, says Apul. One rocket will travel 62 miles and another will climb 186 miles.

Eventually, the researchers hope to test their biphasic liquids with nanobubbles by sending them to the International Space Station, Apul says.

“It’s very theoretical now, but we think it could change the paradigms for using gases in unconventional situations,” says Apul. “This is a new area of ​​research that is only 10 years old and has exciting potential. My slogan for them is “small bubbles, huge potential”.

The project team includes Apul, Ali Abedi, UMaine Associate Vice President for Research and Professor of Electrical and Computer Engineering; Sergi Garcia-Segura; assistant professor of environmental engineering at Arizona State; and Ashanthi Maxworth, assistant professor of environmental engineering at USM. They will collaborate on the project with researchers from NASA’s Johnson Space Center.

Apul has been studying nanobubbles for two years and has worked with various stakeholders interested in their development, including a distillery in Texas. Some of his students are also involved in nanobubble research. One of them, Zach Doherty, a graduate student in civil and environmental engineering, received the Susan J. Hunter Presidential Research Impact Award at the UMaine 2022 student symposium as a fourth-year undergraduate for his investigation of the use of nanobubbles to eliminate drinking water. pollutants. Joseph Patton, a Ph.D. student in the Department of Electrical and Computer Engineering at UMaine who worked with Abedi to develop MESAT1, Maine’s first CubeSat, is also involved in this project and is leading the CubeSat development for it.

The new study will help answer fundamental questions about nanobubbles, after which researchers can embark on investigating other possible applications for them on Earth and beyond, Apul said. The nanobubbles could even serve industries important to Maine, such as aquaculture and pulp and paper manufacturing.

Three doctorates. students, two in Maine and one in Arizona, and three to five undergraduate researchers are expected to work on the study. New equipment purchased for this research will complement existing tools and expand the ability of UMaine and USM scientists to study nanobubble production, characterization and application, Apul said.

“We’re creating the infrastructure, the backbone, for nanobubble research in Maine,” he says. “This is just the beginning.”

Contact: Marcus Wolf, 207.581.3721; [email protected]