Separation of Polycotton for Textile Recycling Using the DBU/DMSO/CO2 Switchable Solvent System

Disposal of textile waste is a growing concern in terms of environmental pollution. Especially, blends of different fibers such as polycotton render recycling of textile wastes difficult, which contributes to low recycling rates in the textile industry. The separation of polycotton into polyester and cotton can enable the recycling of these blended textiles. The selective dissolution of cotton using a switchable solvent system consisting of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU), dimethyl sulfoxide (DMSO), and carbon dioxide is investigated. After the separation of cellulose from polyester, upon addition of ethanol, cotton precipitates, which allows for facile removal from the solvent system. Extraction at 40 degrees C and 5 bar CO2 is feasible for full separation of the constituents of polycotton without degradation of the polyester component, as identified by thermal gravimetric analyses, infrared spectroscopy, size-exclusion chromatography, and scanning electron microscopy of the extracted textiles.