Upcycling Wool Waste to Keratin Gel-Based Nanofibers Using Deep Eutectic Solvents

Abstract

Millions of tons of wool waste are produced yearly by textile industries, which may become a serious environmental hazard in the near future. Given this concern, it is crucial to explore strategies to reduce the amount of wool waste generated worldwide and adopt more sustainable practices for dissolving and regenerating wool keratin (WK) from textile waste. Most traditional methods involve the use of expensive, toxic, harmful, and poorly biodegradable compounds. To overcome these limitations and facilitate the reuse of wool waste through a cascade valorization strategy, researchers have started testing the use of deep eutectic solvents (DES) as a more sus-tainable and eco-friendlier alternative for WK dissolution and regeneration.
 In this study, the potential of two different DES mixtures, Choline chloride (ChCl): Urea and L-Cysteine (L-Cys): Lactic acid (LA), was explored for dissolving wool waste. Subsequently, the obtained gels based on DES-WK were blended with polyvinyl alcohol (PVA) in different ratios to produce nanofibers using the electrospinning technique. The effect of pH and the properties of the electrospinning solutions, namely electrical conductivity and viscosity, on the morphology of the gel solutions were evaluated. Moreover, the morphological features of the produced gel-based electrospun PVA/DES-WK nanofibrous membranes were analyzed using scanning electron mi-croscopy (SEM). Additionally, the PVA/L-Cys: LA DES-WK, which proved to be the most effective DES mixture for fabricating WK gel-based nanofibers, were characterized through Fourier transform infrared spectroscopy (FTIR) and tensile tests. Furthermore, their antioxidant and an-timicrobial abilities were evaluated.
 The results obtained revealed that this approach to valorize textile waste offers a unique avenue for the development of sustainable functional materials with potential applications in various biomedical and industrial fields.