Valorisation scenarios of blended post-consumer textile waste with the focus on thermal processing strategies

Blended textiles present significant challenges for recycling due to the differing physical and chemical properties of natural and synthetic polymers. While current strategies for recycling mono-material textile waste are relatively well-developed and often more straightforward than those for the blended fabrics, in many cases they are limited to downcycling. Consequently, mono-blend recycling approaches are still evolving through advancements in sorting technologies, innovative chemical processing methods, and emerging biochemical techniques. In contrast, valorization approaches for blended textile waste remain largely underexplored, hindering progress in both research and industrial applications. This review explores the challenges and opportunities associated with valorizing blended textile waste, focusing on post-consumer fiber blends such as polycotton. It compares various reprocessing methods, emphasizing thermochemical techniques - including pyrolysis, torrefaction, hydrothermal liquefaction, and gasification. Unlike mechanical, chemical, or biochemical approaches, thermochemical processes are highly adaptable to diverse feedstocks of varying quality and can yield valuable products such as biofuels, chemicals, and filtration materials. Pyrolysis and torrefaction are particularly suitable for decentralized applications, as they require less complex equipment and generate locally applicable products like activated carbon, bio-oil, and syngas. This review highlights the critical role of thermochemical processes in promoting sustainable, localized waste valorization and enhancing the utilization of complex textile waste streams.