Researchers at Princeton School of Engineering have found a way to turn your breakfast food into a new material that cheaply removes salt and microplastics from seawater.
The researchers created an aerogel with protein, a lightweight porous material that can be used in a variety of applications, including water filtration, energy storage, sound insulation, and heat insulation. Craig Arnold, Professor of Mechanical and Aerospace Engineering at Susan Dod Brown and Vice President of Innovation at Princeton University, worked with his laboratory to create new materials, including aerogels, for engineering applications.
One day at the faculty meeting he came up with an idea.
“I sat there staring at the bread in the sandwich,” Arnold said. “I say to myself, this is the kind of structure we need.” So, he asked his lab team to mix carbon and make different bread recipes to see if they could reproduce the aerogel structure he was looking for. At first, they didn’t work well, so the team kept removing ingredients during testing until only egg white was left.
“We start with a more complex system,” Arnold says. “We keep decreasing, decreasing, decreasing until we find its core. It is the protein in the protein that leads to the structure we need.”
Protein is a complex system of almost pure protein that forms a structure interconnected by carbon fiber chains and graphene flakes when freeze-dried and heated to 900 degrees Celsius in an anaerobic environment. Arnold and his collaborators showed that the synthesized material could remove salts and microplastics from seawater with 98% and 99% efficiency, respectively.
Sehmus Ozden, lead author of the paper, said: “Even if fried on a stove first, or hit, the protein can work.” Ozden was a postdoctoral research associate at Princeton Complex Materials Center and is now a scientist at Amy Petroleum Research Center. Ozden says while the initial tests used common proteins purchased from stores, other similar commercially available proteins produced the same results.
“Eggs are cool because we can reach them and they are easily available, but you have to be careful about competing with the food cycle,” Arnold said. Because other proteins also work, this substance can be produced in large quantities at relatively low cost without affecting food supply. Ozden points out that the researchers’ next step is to improve the manufacturing process so that it can be used for water purification on a larger scale.
If this challenge can be addressed, this material will have significant benefits because of its low cost of production, and high efficiency. “Activated carbon is one of the cheapest water purification materials. We compared our results with activated carbon and found much better results. Compared with reverse osmosis, which requires a lot of energy input and excess water operation, this filtration process only requires gravity operation and does not waste water.
Although Arnold considers the purity of water to be a “significant challenge,” this is not the only potential application of this material. He is also exploring other uses related to energy storage and insulation.
The study included contributions from the Department of Chemistry, Bioengineering and Earth Sciences at Princeton University and elsewhere. “Making things in the lab is one thing,” Arnold says. “Understanding why and how to do it is another.” Collaborators who helped answer the questions “why” and “how” included Rodney Presley and Professor a James Lynch from Chemistry and Bioengineering who helped identify the mechanisms of protein transformation at the molecular level. Colleagues in geoscience at Princeton University assisted in measuring water filtration.
Theoretical simulations were created by Suzanne Monty of the Institute for Chemistry of Organometallic Compounds and Valentina Tozy of the Institute for Nanoscience and NEST-Scuola Normale Superiore to reveal the conversion of egg white proteins into aerogels.
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