NEWS
04 July 2024

‘Chemical recycling’: 15-minute reaction turns old clothes into useful molecules

Fast fashion creates millions of tonnes of waste each year — could clever chemistry help to tackle the problem?

By Helena Kudiabor

Researchers have developed a chemical-processing technique that can break down fabrics into reusable molecules, even when they contain a mixture of materials.

The process, outlined in a Science Advances paper on 3 July1, shows that chemical recycling can give old textiles a new lease of life. If scaled up, it could help to tackle the growing mountain of waste generated by the fashion industry, says study co-author Dionisios Vlachos, an engineer at the University of Delaware in Newark.

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The researchers instead turned to chemical recycling to break down some synthetic components of fabrics into reusable building blocks. They used a chemical reaction called microwave-assisted glycolysis, which can break up large chains of molecules — polymers — into smaller units, with the help 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.

For pure polyester fabric, the reaction converted 90% of the polyester into a molecule called BHET, which can be directly recycled to create 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”.

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Chemical recycling of mixed textile waste

ERHA ANDINI, POOJA BHALODE, EVAN GANTERT, SUNITHA SADULA, AND DIONISIOS G. VLACHOS

3 Jul 2024
Vol 10, Issue 27
DOI: 10.1126/sciadv.ado682

Abstract

Globally, less than 0.5% of postconsumer textile waste is recycled, with the majority incinerated or ending up in landfills. Most postconsumer textiles are mixed fibers, complicating mechanical recycling due to material blends and contaminants. Here, we demonstrate the chemical conversion of postconsumer mixed textile waste using microwave-assisted glycolysis over a ZnO catalyst followed by solvent dissolution. This approach electrifies the process heat while allowing rapid depolymerization of polyester and spandex to their monomers in 15 minutes. A simple solvent dissolution enables the separation of cotton and nylon. We assess the quality of all components through extensive material characterization, discuss their potential for sustainable recycling, and provide a techno-economic analysis of the economic feasibility of the process.

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