Upcycling Diverse Textile Waste into Cellulose Nanocrystals Through Composition-Dependent Mild Acid Hydrolysis

The escalating global concern over textile waste highlights the need for effective recycling strategies that can convert discarded fabrics into value-added materials. Cellulose nanocrystals (CNCs) are promising bio-based nanomaterials that can be recovered from cellulose-rich textile waste. In this study, CNCs were extracted from cotton, polycotton, and linen wastes via direct acid hydrolysis with sulfuric and phosphoric acids at a relatively low acid concentration of 27 wt%. The hydrolysis was conducted at 50 °C for 1 h with a solid-to-liquid ratio of 1:20, followed by washing and freeze-drying. The use of 27 wt% acid is significant because it offers a milder hydrolysis route than conventional high-acid CNC extraction methods, thereby reducing chemical consumption and avoiding intensive pretreatment steps such as bleaching, alkali treatment, or delignification. The results showed that CNC yield was strongly influenced by textile composition and acid type, with the highest yield, 90%, obtained from linen waste treated with H2SO4. The products obtained were characterized using FE-SEM, particle-size distribution analysis, BET adsorption–desorption isotherms, and BET pore-size distribution. These findings indicate that mild, direct acid hydrolysis can provide a simplified, low-chemical-input pathway for valorizing diverse textile wastes. The approach offers practical implications for industrial textile recycling by reducing processing steps, minimizing chemical inputs, and supporting the development of composition-specific strategies to convert post-consumer textile waste into high-value cellulose-based materials. Although further crystallinity and nanoscale characterization are required, the results demonstrate the feasibility of mild hydrolysis for textile waste valorization.