Physicochemical Recycling of Cotton from Textile Waste Driven by the Ionic Liquid [DBNH][AcO] via Wet Spinning Through Factorial Design of Experiments

The textile industry is positioned as one of the most significant contributors to waste generation but remains with low implementation of post-consumer recycling practices. In response to this challenge, this study focuses on the physicochemical recycling of cotton derived from textile waste aided by a protic ionic liquid, 1,5-diazabicyclo [4.3.0]non-5-ene acetate ([DBNH][OAc]), as a green alternative solvent for dissolving cotton and generating a dope, which is then transformed into a filament through the wet spinning technique. A dedicated setup was developed for the spinning process, and an experimental design based on a statistical factorial approach was applied to optimise the spinning conditions, as temperature, die diameter and velocity of extrusion. The mechanical properties of the filaments, including tenacity and elongation at break, were analysed to assess their performance. The statistical model facilitated the simultaneous optimisation of both responses—tenacity and elongation—resulting in the following optimal conditions: a temperature of 95 °C, a flow rate of 70 μL·min−1, and an extrusion diameter of 0.4 mm. The results demonstrate that both the selected solvent and wet spinning are effective in producing filaments suitable for reuse in the textile industry. Remarkably, filaments derived from textile waste exhibited superior mechanical properties compared to those obtained from virgin white cotton.