Towards fiber-to-fiber recycling of synthetic textile wastes: the problem of decolorization

Polyester and polyamide are the most widely used synthetic fibers globally, with a combined annual production of approximately 78 million tons. Despite their prevalence, textile waste from these polymers is predominantly landfilled or incinerated due to inefficiencies in recycling technologies. A major bottleneck in textile recycling is the presence of dyes and pigments that compromise material purity and mechanical properties. This review provides a comprehensive evaluation of current decolorization strategies for polyester and polyamide textiles, focusing on three main approaches: back stripping, dissolution-precipitation and depolymerization. Back stripping techniques include solvent-based extraction and adsorption, allowing partial to total dye removal without altering the polymer backbone. Dissolution-precipitation processes offer enhanced purification by selective solubilization, while depolymerization achieves monomer recovery, enabling the synthesis of virgin-like polymers. Environmental and scalability concerns associated with each method are critically discussed, along with recent advancements in sustainable solvent systems. Integrating efficient dye removal into recycling workflows is proposed as a key step to enhance circularity and reduce textile waste, supporting a sustainable transition in the textile industry.