High-quality acrylic fibers from waste textiles

The objective of this work is to develop a closed-loop recycling method specifically tailored for acrylic fibers. Recycling waste acrylic is essential, given the vast volumes of acrylic-containing textiles produced yearly and the strong capability of acrylics to generate toxic microplastics. However, none of the available closed-loop recycling, mechanical recycling, chemical recycling, and direct extrusion technologies work for acrylics. Acrylic fibers are always blended with other textile fibers, making fiber separation via mechanical recycling almost impossible. Polyacrylonitrile, an addition-polymerized thermoplastic material, cannot be depolymerized into its original monomer. Direct extrusion of waste acrylics faces issues of uncontrollable colors on fibers and pollution of spinning lines due to the influence of existing colorants. In our method, acrylic fibers were extracted from waste textiles using a novel approach involving maximized acrylic swelling and dissolution with dimethyl sulfoxide and butanediol. Cationic dyes were effectively removed through cost-effective recycling technology. This work demonstrates that cationic dyes seriously affect the acrylic dissolution, color consistency, and dyeability of regenerated fibers via direct wet extrusion. Such negative impacts of dyes have been eliminated by our cost-effective and closed-loop acrylic recycling technology, which enables the efficient separation of non-acrylic fibers and dyes from acrylic fibers. Our recycling system achieved zero discharges through recycling solvents, dyes, and acrylics. The regenerated acrylic fibers exhibited mechanical properties and dyeability comparable to virgin acrylic fibers. The material and energy costs to produce pure acrylic from waste textiles were only 40 % of those from fossils. This study successfully introduces a closed-loop recycling method for acrylic fibers from waste textiles, addressing key challenges in acrylic fiber recycling. Further research and implementation of this technology are recommended to advance its commercial viability and widespread adoption.