Chemical recycling of polycotton textiles: Fractionation of cotton by TEMPO-mediated oxidation

Developing chemical recycling methods for textiles is needed to improve the sustainability of the textile industry and provide solutions for recycling textile blends. TEMPO oxidation is a little-studied method in the context of textile recycling, although it could enable the upcycling of cotton in the form of nanocellulose. Earlier literature shows that pure cotton textiles can be successfully recycled by the method. This study aimed to fill the gap in the literature by testing if TEMPO oxidation could also be used for separating the materials of polycotton textiles.

This study examined the effects of temperature, pH, and reaction time on the recovery of cotton and polyester as separate fractions. The TEMPO-oxidized polycotton samples were disintegrated using a high-shear mixer. The results showed a significantly lower yield of nanocellulose-like cotton fraction compared to earlier literature. However, the oxidization at a high temperature and pH allowed a high recovery of polyester. The polyester was recovered in fibre form and its purity increased with the temperature, pH, and reaction time. The chemical structure and molecular weight of the recovered polyester were not significantly damaged by the oxidation.

The findings suggest that TEMPO oxidation is an interesting method for recycling polycotton textiles. Further studies are needed to improve the efficiency of material separation and the recovery of cotton.