Once thrown away, disposable items reminiscent of diapers and sanitary pads can take tons of of years to decompose, because their absorbent parts and waterproof layers contain plastics and other synthetic polymers. But now, researchers are replacing these materials with porous components constituted of protein biomass that is usually discarded by the food and agricultural industries. These components are sustainable and biodegradable, and will potentially allow future diapers and sanitary pads to be flushed down a rest room or used as fertilizer.
The researchers will present their results today on the spring meeting of the American Chemical Society (ACS). ACS Spring 2024 is a hybrid meeting being held virtually and in person March 17-21; it features nearly 12,000 presentations on a spread of science topics.
Antonio Capezza, who will present the research on the meeting, says that in Europe, regulations discourage using certain petroleum-based plastics in disposable goods. Nonetheless, there aren’t clear guidelines or regulations to ban these plastics in diapers, sanitary pads and other disposable sanitary items, he notes, because an excellent alternative hasn’t been available. “But we’re hoping to vary that with our protein-based materials.”
After all, washable diapers avoid the plastics issue altogether, but he says that few caregivers need to use them. He’s aiming to offer a special sort of sustainable, non-polluting solution to individuals who need to proceed using disposable sanitary products. “The acceptance rate can be much higher than should you come to a customer and say, ‘Okay, now you will have to clean your diapers,'” explains Capezza, a researcher within the polymeric materials division at KTH Royal Institute of Technology in Sweden.
Satirically, the project had its origins in an indication designed to show students what can go mistaken within the lab. Capezza was showing them make bioplastic filaments using proteins. To mimic the impact of unwanted humidity, he added wet cotton, which caused the mixture to foam. Once the product dried, he realized, the fabric had develop into super porous, meaning it could sop up liquid like a sponge.
“So it was kind of an accident, but an excellent one, because that led us to a completely latest line of research,” he says. Capezza is collaborating with researchers at KTH, the Swedish University of Agricultural Sciences, and other institutions, including Simón BolÃvar University in Venezuela, the University of Tokyo in Japan and the University of Seville in Spain.
Some cotton-based alternatives to plastic sanitary products are already available on the market, but they depend on virgin cotton and might have bleaching or other chemical treatment for his or her production. On the lookout for a more sustainable material source, Capezza’s team identified proteins and other natural molecules left over from food and agricultural production which may otherwise be landfilled or incinerated: as an example, zein from corn, gluten from wheat and natural antioxidant extracts.
The researchers mixed the proteins together in numerous proportions and added water and bicarbonates, reminiscent of baking soda, as foaming agents; the sweetener glycerol as a plasticizer; and natural extracts as preservatives.
The team then used equipment and processing techniques from the plastics industry, including extrusion, to make various components commonly present in pads and diapers. Just like a pasta maker, the extruder enabled the team to supply filaments and flat sheets while at the identical time allowing them to foam the materials. With these techniques, the researchers produced a flat “nonwoven” layer that remained dry to the touch while allowing liquid to rapidly go through; a fluffy porous material with superabsorbent properties that captured liquid; and waterproof movies to guard outer garments.
As a proof of concept, the researchers assembled these components to make protein-based absorbent prototypes that resembled disposable sanitary products. Once exposed to water or soil, the materials completely biodegraded in just a few weeks. Due to materials’ protein origin, this degradation released carbon, nitrogen, phosphorus, amino acids and other compounds that nature can reuse as nutrients.
With further development, Capezza says, this may lead to single-use sanitary products that could be flushed. Alternatively, after use, these products (or any waste produced on the manufacturing stage) could possibly be composted to fertilize crops, reminiscent of corn and wheat, which might in turn provide the starting materials to make latest sanitary products. “So it’s a totally circular design,” Capezza adds. The researchers have already shown that plants grow longer leaves and roots when exposed to this compost. “And our tests have shown that since it’s protein based, there isn’t any risk by any means that these products will pollute the soil with microplastics or other unwanted chemicals after they break down.”
Protein-based sanitary products could be about 10 to twenty% costlier than traditional plastic diapers and pads, Capezza estimates. The performance of protein sanitary pads is comparable to that of conventional pads. Then again, protein diapers aren’t as absorbent as their plastic counterparts. Which means protein diapers would either should be thicker, or their formulation would should be tweaked to enhance absorption. To spice up liquid uptake and mechanical strength, the researchers at the moment are exploring the addition of lignocellulose, a mix of lignin and cellulose that is present in plants. This material is a low-value byproduct of the farming and forestry sectors. Results up to now show its addition is bringing performance near that of conventional diapers.
The team is now preparing for pilot studies to check the feasibility of scaling up production. Additional evaluations, including human skin irritation tests, will should be done before any of those products can go available on the market, Capezza says.
The research was funded by the Bo Rydin Foundation and Formas, a Swedish government research council for sustainable development. The team has filed a patent application on the technology and process.
