At a textile-recycling shop in Taiwan, piles of used clothing wait to get sorted. Credit: Annabelle Chih/Getty
Researchers have developed a substance control technique that can transform fabrics into washable molecules, even when they are mixed with a variety of materials.
The method, described in a Technology Advances document on July 3, 2018, demonstrates how chemical recycling does give worn-out fabric a new lease of life. According to research co-author Dionisios Vlachos, an expert at the University of Delaware in Newark, if it were scaled up, it may help address the growing pile of waste generated by the fashion industry.
Less than 1 % of fabric are recycled, and practically three-quarters of used clothing goes to the garbage or is incinerated, according to projections. ” A good second or more of the plastic that end up in the sea” come from clothes, says Vlachos. It is crucial for us to be able to create systems that can handle all this misuse and get it out of landfills, oceans, and the atmosphere.
Although recycling should be considered a last resort after reparing and reusing old clothes, the economy had allowed “investment in these new processes and technologies to be able to level up,” according to Miriam Ribul, who researches green materials at the UKRI Textiles Circularity Centre.
Tricky textiles
Physically separating waste into raw materials is a common practice in recycling, but this method has drawbacks when it comes to handling textiles. Many fabrics are composed of a variety of materials, like cotton that has been combined with polyester to create synthetic fibers. Multi-fiber textiles are a product that can be used again, but mechanical recycling techniques struggle to separate them into products that can be used again. ” The quality of what you get is reduced”, says Vlachos.
How to incorporate clothing into the circular economy
Instead, the researchers turned to chemical recycling to transform some synthetic fabrics into reusable building blocks. They used a technique known as microwave-aided glycolysis, which allows the breakdown of large chains of molecules— polymers — into smaller units with the aid of heat and a catalyst. They used this to process fabrics with different compositions, including 100 % polyester and 50/50 polycotton, which is made up of polyester and cotton.
90 % of the polyester was transformed into a molecule known as BHET, which can be directly recycled to make more polyester textiles. The researchers found that the reaction didn’t affect cotton, so in polyester–cotton fabrics, it was possible to both break down the polyester and recover the cotton. Crucially, the team was able to optimise the reaction conditions so that the process took just 15 minutes, making it extremely cost- effective. ” Typically, these things take days to break them down. So, going down from days into a few minutes, I think this is a major renewal”, Vlachos says. Eventually, he says,” I think we can actually go down into seconds”.
Scaling up
Additionally, the study looked into how other material combinations react with the reaction process. The results were good even when textiles contained unknown proportions of fibres including cotton, polyester, nylon or spandex. Spandex broke down into a useful molecule called MDA, and nylon, like cotton, could be extracted intact. However, some polyester materials, such as dyed fabrics and those that had been treated to be resistant to ultraviolet light or fire, produced lower levels of BHET. The team suggests that more research is required to optimize the conditions for such materials.
In an analysis as part of their study, Vlachos and his colleagues estimated that, with further development, 88% of clothing worldwide could be recycled.
“We have a simple process that we can scale to treat large quantities of clothing”, says Vlachos. We have high hopes that this can be applied to the real world.