Your breakfast food can be transformed into a novel substance that can easily remove salt and microplastics from seawater, according to Princeton Engineering researchers
Aerogel, a light and porous substance developed by researchers using egg whites have a wide range of uses, including acoustic and thermal insulation, energy storage, and water purification.
As vice dean of innovation at Princeton and the Susan Dod Brown Professor of Mechanical and Aerospace Engineering, Craig Arnold collaborates with his lab to develop new materials, such as aerogels, for use in engineering.
He had an idea one day while attending a faculty meeting.
"I was sitting there, staring at the bread in my sandwich," said Arnold. "And I thought to myself, this is exactly the kind of structure that we need." So he asked his lab group to make different bread recipes mixed with carbon to see if they could recreate the aerogel structure he was looking for. None of them worked quite right initially, so the team kept eliminating ingredients as they tested until eventually, only egg whites remained.
"We started with a more complex system," Arnold said, "and we just kept reducing, reducing, reducing, until we got down to the core of what it was. It was the proteins in the egg whites that were leading to the structures that we needed."
When freeze-dried and heated to 900 degrees Celsius in an atmosphere devoid of oxygen, egg whites, a complex system of almost pure protein, produce a structure of intertwined carbon fibres and sheets of graphene. Arnold and his coauthors demonstrated the effectiveness of the final material in removing salt and microplastics from seawater in a paper that was published on August 24 in Materials Today.
"The egg whites even worked if they were fried on the stove first, or whipped," said Sehmus Ozden, the first author of the paper. Ozden is a former postdoctoral research associate at the Princeton Center for Complex Materials and is now a scientist at Aramco Research Center. While regular store-bought egg whites were used in initial tests, Ozden said, other similar commercially available proteins produced the same results.
"Eggs are cool because we can all connect to them and they are easy to get, but you want to be careful about competing against the food cycle," said Arnold. Because other proteins also worked, the material can potentially be produced in large quantities relatively cheaply and without impacting the food supply. One next step for the researchers, Ozden noted, is refining the fabrication process so it can be used in water purification on a larger scale.
The material has considerable advantages if this problem can be resolved because it is cheap to create, energy-efficient to use, and extremely effective. One of the least expensive materials used for water treatment is activated carbon. Our outcomes are far superior when compared to activated carbon, according to Ozden. This filtration technique uses only gravity and wastes no water, in contrast, to reverse osmosis, which operates with a substantial energy input and excess water.
Although Arnold considers water purity to be a "huge great problem," there are other possible uses for this substance. He is also looking into further applications for insulation and energy storage.