2 days ago
Northwestern University scientists develop possible replacement for PFAS, common "forever chemicals"
They're in cookware, cosmetic products, clothing, tap water, and even detectable in human bodies – PFAS, a group of synthetic chemicals.
PFAS are known as "forever chemicals" because they resist breaking down and can stay in the body for prolonged periods of time.
However, a new nontoxic material developed by Northwestern University scientists could replace these harmful chemicals in paper-based food and beverage packaging.
Professor of Chemistry SonBinh Nguyen and Professor of Engineering Tim Wei have developed a graphene oxide solution that is water- and oil-resistant, more compostable, and recyclable than the current average paper plate or take-out cup.
The patient-pending product is being commercialized by Go-Eco, a subsidiary of Chang Robotics, where Wei is chief scientist, and a resident startup at Northwestern's Querrey InQbation Lab.
Twenty years into Nguyen's research on graphene oxide, Wei came to Northwestern to give a talk about the engineering of food manufacturing before he had worked there. They remained in touch and formed a partnership over the last decade.
The team has successfully tested the material on cardboard boxes, plastic produce bags, plates, cups, and straws.
What are PFAS?
PFAS stands for per- and polyfluoroalkyl substances. These chemicals resist grease, oil, water, and heat. According to the National Institute of Environmental Health Sciences, PFAS do not degrade easily in the environment because their molecules have one of the strongest bonds. Because of this, PFAS break down slowly, if at all.
If you grabbed a cup of coffee at your local convenience store not so terribly long ago, that cup would have contained PFAS.
"Even 10 years ago, if you remember a paper cup, the outside of the cup was paper, but the inside had this sort of plasticky coating to it, and so that literally would be like a plastic, or it could be a PFAS, and that was essential to make sure your cup of coffee didn't disintegrate in your hand while you're still trying to drink it," explained Wei.
A study done by the Centers for Disease Control and Prevention found PFAS in the blood of 97% of Americans.
There are over 15,000 types of PFAS, according to the U.S. Environmental Protection Agency. Although not all of them are in use, many are hard to detect.
The EPA says it will require public water systems to monitor the level of 6 PFAS by 2027.
PFAS arealso detected in food, soil and air, in addition to the consumer Johns Hopkins Bloomberg School of Public Health says that PFAS can last thousands of years.
How the graphene oxide material works
Graphite — a naturally occurring crystalline form of carbon — is a common everyday substance best known as pencil "lead" (actual lead was never used in pencils despite the name). Graphene is a single, two-dimensional layer of graphite — simply a sheet of carbon atoms arranged in a hexagonal lattice structure.
Nguyen called it "hexagonal chicken wire."
Graphene oxide is synthesized when graphene is exposed to oxygen. This process causes the substance to form functional groups — that is, structures that are responsible for reactions.
Importantly, graphene oxide with its functional groups is water soluble, while pure graphene is a solid and is not soluble in anything.
"So it becomes a solution that we can use to spray, to coat, to integrate it with paper making," explained Nguyen.
Specifically, an oxygen function group in the graphene oxide binds onto the fiber of the paper and changes its properties — making it hydrophobic, or resistant to water. Graphene oxide also makes paper more resistant to oil, and reduces the amount of water vapor and gases that make contact with the paper, Wei explained.
In other words, graphene creates a barrier when applied to paper.
Studies also showed that graphene increases the strength of the substance to which it is applied.
In Nguyen's early research, adding graphene oxide to a synthetic polymer, or plastic, dramatically increases its Young's modulus — a measurement of how strong a material is under compression or tension. Graphene oxide also increases the polymer's tensile strength — essentially, the force required to pull it apart.
When graphene oxide is used on paper, such as a to-go cup, data likewise document a 30% to 40% increase in strength, Wei said.
Better for the environment and health
Graphene oxide is safer than PFAS because it is derived from carbon, according to Nguyen.
"It resembles a carbohydrate," he said. "Graphene oxide will degrade in the environment the same way wood does biologically."
Because graphene oxide is also water soluble, the theory is that it would not stick or stay inside the body the same way microplastics and PFAS do. The team said they are not yet at the step of getting FDA approval and will test this and verify their theories.
"This material would be a lot safer for the environment, and a consumer could know that their disposable cup of coffee can safely go in the dumpster or to the compost without spreading harmful chemicals," Nguyen said.
Graphene oxide has been shown to be able to filter out heavy metals from tap water, according to research done at MIT in 2021.
Northwestern estimates that the U.S. produces approximately 14 million metric tons of paper-based food packaging and corrugated cardboard every year, many of which are coated with PFAS.
Next steps
"The problem is PFAS work really well and are really inexpensive, but as we learn as a society, that those are really problematic materials, they have to be removed," Wei said.
Nguyen said the scientists are trying to "solve a little bit at a time," while pushing ahead in search of an even better alternative.
Their long-term goal is to create a paper-based material that replaces plastic for food packaging for produce and meat, paper bags and tableware.
The team received funding from a major national tableware manufacturer and is in talks with several companies to try pilot testing.
"We work on this to make an impact on our future, our children, grandchildren, and for the whole earth," Nguyen said.
