Polyester, the second most widely used textile in the world, poses a significant environmental challenge due to its low recycling rate. A group of innovative chemists from the University of Copenhagen has come up with a remarkable solution, using a single household ingredient, to address this pressing issue. Their groundbreaking approach allows them to depolymerize polyester into its monomers while simultaneously recovering cotton, making the process environmentally friendly and straightforward.
Currently, the textile industry struggles to recycle blended fabrics like polyester/cotton, often resulting in either the loss of plastic or cotton fibers. However, with this newly discovered technique, the chemists can achieve a scale of hundreds of grams in recycling while preserving both components. The absence of metal catalysts in the process reduces complexity and eliminates potential contamination.
The impact of polyester production on the climate and environment is significant, with only 15% of it being recycled annually, while the rest ends up in landfills or incinerators, contributing to carbon emissions. This breakthrough solution has the potential to revolutionize the sustainability of the textile industry by offering an efficient and green method to recycle polyester and cotton blends, reducing waste and promoting a more environmentally friendly future. The research article, authored by postdoc Yang Yang of the Jiwoong Lee group at the University of Copenhagen’s Department of Chemistry, highlights the transformative nature of this traceless catalytic methodology.
Hartshorn salt and 24 hours in the ‘oven’
A groundbreaking new method for recycling polyester has emerged, requiring nothing more than heat, a non-toxic solvent, and a common household ingredient. Developed by chemists from the University of Copenhagen, this simple yet effective process involves cutting a polyester dress into small pieces, adding a mild solvent and hartshorn salt (ammonium bicarbonate), and heating it to 160° Celsius for 24 hours. The result is a liquid where the plastic and cotton fibers separate into distinct layers, making it easy to recover both materials.
The key to this breakthrough lies in the decomposition of hartshorn salt into ammonia, CO2, and water. The combination of ammonia and CO2 acts as a catalyst for selective depolymerization, breaking down the polyester while preserving the cotton fibers. What’s remarkable is that although ammonia is toxic on its own, when paired with CO2, it becomes environmentally friendly and safe. Thanks to the mild nature of the chemicals involved, the cotton fibers remain intact and undamaged.
Previously, the same research group had successfully used CO2 as a catalyst to break down nylon without leaving any trace. This led them to explore the use of hartshorn salt for polyester recycling, and their simple recipe delivered promising results.
The researchers are enthusiastic about the scalability of this technique and have begun discussions with companies to test it on an industrial level. Their goal is to commercialize this eco-friendly technology, as keeping such valuable knowledge confined to the university would be a missed opportunity. With the potential to revolutionize polyester recycling, this method could pave the way for a more sustainable textile industry.