Using Egg Whites To Remove Microplastics

Scientists from Princeton Engineering have created a new material using egg whites. The material – an aerogel – can be used to purify water, removing microplastics, with a high efficiency. The study is published in Materials Today.

Inspired by a sandwich

Professor Craig Arnold’s laboratory at Princeton University develops novel materials for engineering applications, such as purifying water. This, says Arnold, is a “grand challenge”. It is also one of several potential applications of a novel material that his research team have created using egg whites.

The material is a lightweight and porous aerogel. The journey to its creation began when Arnold was eating a sandwich during a faculty meeting and became somewhat fixated on the bread’s porous structure. “I thought to myself, this is exactly the kind of structure that we need,” he recalls.

He tasked his lab with creating different bread recipes using varied amounts of carbon to create the aerogel structure that he was searching for. Eventually, all ingredients were eliminated bar egg whites. “We started with a more complex system, and we just kept reducing, reducing and 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,” says Arnold.

Egg whites used to make interconnected structure

Egg whites are made of ~90% protein (including ovalbumin, ovomucoid and ovotransferrin, among others) and water. When egg whites are frozen and heated to 900 degrees Celsius in an environment lacking oxygen, they form an interconnected structure of carbon strands and graphene sheets. Arnold and team demonstrated that this material can be used to remove salt and microplastics from seawater, with 98% and 99% efficiency.

The eggs used in the study were bought from a regular food store, but the authors say that other commercially available proteins produced the same results. “The egg whites even worked if they were fried on the stove first, or whipped,” says Dr. Sehmus Ozden, first author on 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.

“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,” says Arnold.

The material can be produced at-scale at a relatively cheap cost due to the ease by which the proteins can be sourced. The next step for the research group, says Ozden, is to refine the fabrication process, such that it can be adopted for water purification on a larger scale.

Reference: Ozden S, Monti S, Tozzini V, et al. Egg protein derived ultralightweight hybrid monolithic aerogel for water purification. Mater Today. 2022. doi: 10.1016/j.mattod.2022.08.001.

This article is a rework of a press release issued by Princeton University. Material has been edited for length and content.