Eco-friendly post-consumer cotton waste recycling for regenerated cellulose fibers.

In this study, post-consumer cotton waste was chemically recycled to produce regenerated fibers using eco-friendly alkaline/urea solvent systems. Both white and colored cotton waste was shredded and hydrolyzed using sulfuric acid to reduce the molecular weight of the cotton fibers. Two solvent systems, i.e., sodium hydroxide/urea and lithium hydroxide/urea, were used to dissolve the hydrolyzed cotton to prepare solutions for fiber regeneration by wet spinning. The diameter, morphology, thermal properties, crystallinity, and tensile properties of the regenerated fibers were characterized by SEM, TGA, XRD, and tensile testing. Results showed that, using this recycling method, fibers with tensile properties comparable to current commercial regular rayon fibers made from wood pulp could be produced, and dyes in the original cotton waste could be conserved to produce fibers with intrinsic colors, thus eliminating the need for dyeing processes. This study demonstrated an economical upcycling method for post-consumer cotton waste with environmentally friendly solvents.