RECYCLING old clothes is no mean feat, especially garments made from mixes of different fibres. But the tide may be turning, thanks to the results of research by Danish scientists.
They have developed a new technology capable of separating the various fibres of a garment so that they can be processed and used again.
Fashion is one of the world's most polluting industries, and waste management — including used clothing — is now central to efforts to reduce this environmental impact.
In addition to the hundreds of thousands of tonnes of plastic microparticles released into nature and the oceans every year -— particularly when clothes are machine-washed — 80 per cent of textiles disposed of each year (4 million tonnes in Europe alone) end up in the household trash, according to data from the French Agency for Ecological Transition.
While the rules are becoming stricter in Europe, the proportion of recycled textiles is still low because it's not easy to recycle a garment containing several different fibres, such as nylon, elastane and cotton. Yet, these kinds of blends are very commonly used.
Researchers at the Interdisciplinary Nanoscience Center at Aarhus University, Denmark, have looked into that matter to develop a technology that could soon change the game.
"We've developed a method to remove elastane completely from nylon. We're not quite there yet with cotton, because some of the cotton fibres are broken down in the process. But we believe that, with some minor adjustments, we can solve this problem," says study co-author, Steffan Kvist Kristensen, quoted in a news release.
Although the technology is not yet fully perfected, the scientists are pleased to be able to remove elastane from nylon, a major step forward in textile recycling.
Separating elastane — the fibre used to make garments stretchy — from other materials is one of the biggest challenges in textile recycling. The researchers explain that "clothes are made by winding the main fibres, such as nylon or cotton, around the elastane fibres, which consist of long chains of molecules. The fibres only break apart if we break the long chains of molecules."
For the purposes of their research, the scientists heated the garments to 225ºC in a sort of large pressure cooker, and added alcohol and a specific base before letting the whole thing "cook" for four hours.
This operation separates the various fibres, in particular the elastane, whose bonds had broken. The base in question is potassium hydroxide — an ingredient in certain detergents, soaps and other cleaning products.
"We found that adding it accelerated the process by increasing the speed of the chemical reaction," says Kristensen.
This breakthrough could make it easier to recycle a wide range of garments, especially those containing elastane, such as underwear, pants, swimwear and tights which are difficult to recycle.
The researchers point out, however, that their technology is not yet ready for implementation at industrial scale because it can only break down a limited amount of clothing at this stage.
