Australia – Researchers at Deakin University in the Australian state of Victoria have found a way to separate blends of cotton-polyester material, hailing this as ‘a major breakthrough’ for recycling textile and other waste.
A significant hurdle to recycling waste clothing and other textiles into their original fibres is that most of this material is composed of blended fibres – the most common being polyester/cotton blends. While it is easy to recycle cotton and polyester individually, it is not possible to mechanically separate the blends where the fibres are closely bonded together.
Chemical solutions attempted to date have not been viable economically or environmentally, it is explained. However, researchers at Deakin’s Institute for Frontier Materials – Dr Nolene Byrne and PhD student Rasike De Silva – have developed a simple process to separate polyester-cotton blends into their individual components using an ionic liquid, or a salt in a liquid state.
Unlike harsh solvents which have previously been used to dissolve polyester, ionic liquids ‘provide an environmentally friendly solvent’ to chemically separate polyester/cotton blends. Another benefit of using ionic liquids, says De Silva, is the ease with which the polyester and cotton can be separated.
‘The ionic liquid selectively dissolves the cotton component, with the added advantage that the liquid can then be recycled and reused,’ he explains. ‘This cotton can then be regenerated into various forms, such as spun into fibres or cast as cellulose films, like cellophane.’
The recovered polyester can also be recycled by melting and reshaping it into other forms, such as plastic bottles or fibres. Regenerated cellulose fibres such as viscose, rayon and lyocell have a considerable market share and are growing in popularity, it is noted.
Regenerated cotton is also increasingly being used as a low-cost precursor in the carbon fibre industry and as the starting material for bioethanol production.
The new process is not limited to textile recycling but can also be applied to the recycling of any type of biocomposite material – including those used in the automotive industry, according to the researchers.
A textile engineer from Sri Lanka, De Silva has carried out the project as part of his PhD research into separation and utilisation of polymer fibre blends using environmentally-friendly approaches.
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