Transforming post-consumer cotton waste textiles into viscose staple fiber using hydrated zinc chloride

Large amounts of cellulose-based waste textiles are generated every year, yet little is done to recycle this waste. Alternatives such as fiber-to-fiber recycling, where a significant part of the value of the waste textiles is recovered, are attractive possibilities. In this study, we have investigated the viability of using hydrated zinc chloride (ZnCl2·4H2O) as a solvent and swelling agent to convert cotton waste textiles (the most abundant cellulose-based waste textile) into a dissolving pulp that can be used as raw material for the production and spinning of viscose fibers. The solvent produced an accessible dissolving pulp and exhibited excellent recyclability, maintaining good dissolving power even after repeated recycling. The dissolving pulp was subsequently used to produce viscose dope, a spinning solution which was spun and cut into viscose staple fibers. The viscose dope exhibited good properties (moderate filter clogging value and gamma number), and the resulting staple fibers were strong and of good quality (high linear density, elongation, and tenacity). These results illustrate the potential of using hydrated zinc chloride for the production of viscose grade dissolving pulp from cotton waste textiles. Open access funding provided by Lund University. This work was funded by the Swedish Energy Agency (project number 51217–1) and ShareTex AB. ShareTex AB financed the zinc chloride used in this work. Furthermore, ShareTex AB also funded the treatment of cotton textile waste with zinc chloride as well as the experiments on recycling of zinc chloride. The rest was funded by the Swedish Energy Agency.