Researchers in the US have created a way to break down old polyester clothing and reuse some of its compounds to make fabrics that are fire resistant, anti-bacterial or wrinkle-free—and to halt the proliferation of garment waste in landfills.
- The researchers know that to succeed, their technique must be adaptable to existing industry practices. They are hoping that manufacturers will use the concept in existing infrastructure.
- The research was led by Juan Hinestroza, the Rebecca Q Morgan ’60 Professor of Fiber Science and Apparel Design in the College of Human Ecology at Cornell University. Others involved include Phill Milner, assistant professor of chemistry and chemical biology in the College of Arts and Sciences, and Jin Suntivich, associate professor of materials science and engineering in Cornell Engineering.
- The team believes that the new techniques can disrupt the business-as-usual textile and apparel processes, which they say are unsustainable.
The Research: Scientists can extract an old fabric’s monomers from a “soup” and use them to create linkers to be assembled into metal-organic frameworks, or MOFs.
- The laboratory “soup” is an assortment of colorful strips of polyester fabrics that are put inside a small round-bottom flask over which a sodium hydroxide solution is poured to cover the textile. With agitation, a little applied heat, ethanol and cooling water, those tiny pieces of polyester cloth—made of polyethylene terephthalate, the kind of goop from which plastic soda bottles also are made—become the laboratory soup.
- The MOF structures can be used to create coatings on clothing that protect people from germs or noxious gases, to shield firefighters from fire or other uses not yet imagined.
- Instead of using toxic solvents to recover the monomers to link the MOFs, the researchers have been using ethanol and water as solvents—and reclaiming the monomers significantly faster.
- With the right metal salts, like some copper salts, they can chemically grab the organic molecule from the monomers recovered from the digested textiles. Within 30 minutes the polyester is depolymerised—safely and without environmental destruction—at room temperature.
- The chemistry is governed by the idea of self-assembly, which is that the components themselves want to become an ordered structure.
- The scientists add copper salts to an acid to create a precursor solution, which they then bring to the soup of depolymerised polyester. The natural process keeps going until it builds an extended structure—the MOFs—which is what comes out of the solution.
EARLIER WORK: In earlier research projects, Hinestroza had created naturally fibrous materials to selectively capture or decompose harsh contaminants like dyes from textile manufacturing, arsenic from fracking, mercury and cyanide from coal mining, and insecticides and fertilizers from agricultural production.
- The seed of those projects was planted while Hinestroza was traveling in his native Colombia. He noticed that large bags for packaging coffee beans were made from a strong fibre called fique. Under a microscope, the fibre revealed cavities where manganese oxide can loiter. When the fibrous cloth was placed in polluted water, the manganese oxide decomposed 99% of the indigo dye within minutes—making the water clear.
- Looking for a local material that would do the same thing, Hinestroza thought to use fibre made from the peels of Cortland apple grown at Cornell Orchards and the stems of grapes sold at the Ithaca Farmers Market. Six years ago, he showed how nanorods created using those natural materials could also decompose toxins in waterways.
- Hinestroza thinks the same concept, but using the MOF textiles, could help halt some of the pollution generated through textile and apparel manufacturing.
WHAT THEY SAID:
We have to proactively find answers for this business, and that is a key motivation for our research work. The menacing problem is not only the waste generated in future textile and apparel production, but also the waste and pollution that has been already generated, which will not suddenly vanish.
— Juan Hinestroza
Rebecca Q Morgan ’60 Professor of Fiber Science and Apparel Design, College of Human Ecology
Cornell University
