Disposable diapers make many a modern, eco-conscious parent fret. Mainstream diapers are made of plastic, petroleum-based absorbent layers, and chemicals that are harmful to babies and the planet. And the average baby goes through 5,000 before they are potty-trained.
Now researchers have come up with a new bio-based material for sustainable diapers: wheat gluten, the main protein in wheat. The highly absorbent gluten-based material, which they report in the journal Advanced Sustainable Systems, could also be used in other hygiene and medical products, and for uses such as flood water retention.
Driven largely by consumer demand, several brands of eco-friendly disposable diapers already exist on the market. They are typically made from bamboo, cotton, or plant-based pulp.
To make an even more sustainable alternative, Scientists at KTH Royal Institute of Technology in Sweden focused on materials that are waste products of agricultural processing streams. “If we want to be sustainable, we need to use raw materials that are renewable and that are not going to interfere with the main food production chain in the future,” said lead author Antonio Capezza in a press release.
The team chose wheat gluten protein, which is the byproduct of wheat starch and ethanol production. That means using it millions of diapers would not be competing with food sources. The material is already known to be super-absorbent. But by chemically tweaking it, they were able to increase its swelling capacity by over 10 times.
In the past, others have boosted gluten’s swelling ability by adding molecules known as protein cross-linkers. But the molecules that have been used before are regarded as toxic, which makes them less than suitable for use in health-care products. Here the researchers used a natural non-toxic cross-linker called genipin, which is an extract from the fruit of the cape jasmine evergreen plant.
The new material is capable of swelling up to 4,000 percent in water and 600 percent in saline solution. That’s comparable to other bio-based absorbent materials. But by further modifying the material, the researchers believe that its absorbency could match that of it’s petroleum-based counterparts.
Source: Capezza, A. J., et al. Superabsorbent Polymers: High Capacity Functionalized Protein Superabsorbents from an Agricultural Co‐Product: A Cradle‐to‐Cradle Approach. Advanced Sustainable Systems, 2020.