Upcycling cotton textile waste into bio-based building blocks through an environmentally friendly and high-yield conversion process

This work presents mechanical refining as a chemical-free pretreatment of cotton textile waste to be converted into glucose via enzymatic hydrolysis. Both Cellic® CTec2 and CTec3 cellulase enzymes were evaluated to perform the enzymatic hydrolysis. Mechanical refining enabled cotton fiber fibrillation, thus increasing its specific surface area, water swellability, enzyme adsorption, and the efficiency of cotton conversion into sugars. Compared to conventional pretreatments, mechanical refining promoted sugar yields above 90% after enzymatic hydrolysis at lower enzyme usage (4–6 FPU/O.D g). From experimental data, a non-linear model was developed to predict cotton conversion. The predictive model allowed the optimization of the conversion process, which resulted in maximum yields of 89.3 and 98.3% when CTec2 and CTec3 were respectively used. Results from this work open the window to deploy mechanical refining as a promising and more sustainable transformation approach to produce sugar-based building blocks within the circular economy framework of textile waste.