2023-08-21 17:28:59
That new T-shirt or the white socks you put on for sports: both garments contain polyester, a common plastic that is made from oil.
Now the EU wants 75 percent of all textiles to be recycled by 2030. But at least that won’t work for a long time now. One of the reasons is that clothing is difficult to recycle, especially polyester clothing. But researchers at the University of Copenhagen present a new, potentially promising method for that.
Currently, recycling involves melting down polyester and then spun it into a new polyester fibre. Bottles, other packaging and clothing can be made from it. Another way of recycling is to use chemical processes to return polyester to the building blocks that make up the plastic. They can then be reused for clothing. But that is an expensive process that takes a lot of energy.
Researchers at the University of Copenhagen have developed a method that appears to cost less energy and is also more environmentally friendly. It works as follows: for example, the researchers heat a piece of sports sock together with deer horn salt and a solvent to 160 degrees. After it has been left alone for a day, cotton and plastic are left separated from each other.
Stag horn salt used to be a home garden and kitchen product. It is made from the natural minerals ammonium sulfate and calcium carbonate and was used as a baking powder, but because of its peculiar, ammonia-like smell, it has disappeared from most households. “Other methods use chemicals. We want to limit the effect on the environment, so we use a natural substance,” says one of the researchers, Shriaya Sharma, on the phone from Copenhagen.
Blouse with buttons
Another advantage of this method is that it only works with polyester and cotton. So suppose you throw a blouse with buttons in such a recycling bin, they don’t disrupt the process. “As a test, we put clothes in a bin with waste to see if the method would still work,” says Sharma. “The plastic and cotton were neatly separated and the other products floated. We might easily get them out.”
“It is an interesting technology,” says Esther van den Beuken, plastics expert at TNO. “In one step, the plastic can be separated from the cotton and recycled with high quality. That is not possible with current methods.” She does emphasize, however, that the Danes have only worked on a lab scale and have not yet demonstrated that their innovation also works on a large scale. “It is still too early to determine whether the method will be successful,” she says.
High temperatures
Van den Beuken does have one point of criticism with regard to the Danish method: the temperature. It is not as high as the 200 to 240 degrees with current recycling methods, but at 160 degrees it is still quite high. This requires a lot of energy and can therefore be harmful to the environment. “A lower temperature is not yet possible,” says Sharma. “The amount of cotton and polyester left following separation decreased at a lower temperature.”
The Danish researchers themselves are convinced that they have discovered the future of clothing recycling. The next step is scaling up. Sharma: “We now have to work with kilos, instead of grams.” They want to do this in collaboration with large recycling companies. If that proves successful, this one method will not be enough to meet the ambitious EU targets for clothing recycling. But it does bring them a little closer.
Read also:
How do clothing stores ensure that they will recycle half of it in the future?
A new law obliges clothing companies to recycle or reuse half of the jeans, blouses and socks sold over two years. How will the sector achieve this?
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