Researchers at TU Wien have created a new method to separate and recycle mixed textiles efficiently using two common substances, menthol and benzoic acid. Although both are solid at room temperature, they form a liquid when combined, known as a deep eutectic solvent. This liquid is easy to produce, non-toxic and has strong dissolving properties.

When this special solvent is heated to 216°C, it triggers a quick separation process. Within five minutes, the polyester in the blended fabric dissolves completely, while the cotton stays unchanged. The cotton can then be washed, dried and reused, and the dissolved polyester settles out as the mixture cools, allowing it to be collected and recycled.

The method recovers 100% of the cotton and 97% of the polyester, achieving an almost complete recycling rate. What makes the process especially impressive is that neither cotton nor polyester is damaged or chemically changed. Tests show that the cotton fibres remain strong and maintain their original qualities, making them suitable for spinning into new yarns. The polyester also retains its structure and melting temperature, proving that the process is both gentle and effective.

Traditionally, polyester is chemically broken down into smaller molecules during recycling. This new technique keeps the polyester chains intact, helping maintain the material’s original quality.

So far, the process has been demonstrated only in the lab, but the research team led by Nika Depope and Andreas Bartl believes it has strong industrial potential. The recovered cotton and polyester can be reused in many applications, including new yarns, fibres, nonwovens and technical textiles.

The team is now working on reducing the energy needed for the process, as the high temperature of 216°C is a current limitation. However, they are optimistic that further improvements can be made and that this method could eventually be adopted on an industrial scale.