Targeted depolymerization of waste cotton textiles mediated by deep eutectic solvents: High-value recycling of waste...

The annual generation of waste cotton textiles is substantial, yet the recycling rate remains limited. Waste cotton textiles represent an abundant cellulose-rich resource for high-value recycling, yet their excessively high degree of polymerization (DP) limits direct dissolution and subsequent regeneration into cellulose fibers. This study employs a hydrated choline chloride/lactic acid/water deep eutectic solvent to convert waste cotton textiles into high-purity dissolving pulp through targeted depolymerization. By tuning the water content to 30%, the DP of waste cotton pulp was controllably reduced from 2409 to the range of 500-700, while preserving chemical composition and crystalline structure. The resulting dissolving pulp exhibits an α-cellulose content of 98.80%, a whiteness of 85.80%, an iron content of 17.01 ppm, and a pulp yield of 88.01%. Moreover, the DES achieved a recovery rate of 80.80%. The dissolving pulp was successfully processed into regenerated cellulose fibers using wet-spinning, giving fibers with a breaking strength of 1.27 cN·dtex^-1 and an elongation at break of 13.63%. This work establishes a novel solvent-mediated strategy for the sustainable valorization of waste cotton fabrics into high-quality regenerated cellulose products, providing an energy-efficient and environmentally benign pathway for the high-value recycling of cellulose-rich textile waste.