Valorization of post-consumer cotton-rich textile waste into cellulose nanocrystals via sulfuric acid hydrolysis and ozone-assisted bleaching

The increasing global production of textile waste presents a critical environmental challenge, with most discarded materials ending up in landfills or incinerations. Existing recycling and upcycling technologies remain limited in efficiency and sustainability, highlighting the need for more sustainable valorization approaches. This study proposes an optimized method for extracting cellulose nanocrystals (CNCs) from post-consumer cotton-rich textile waste using sulfuric acid hydrolysis with ozone-assisted bleaching as a green purification approach. By refining reaction conditions, CNCs yield of 54.09 ± 3.47 % before and 55.88 ± 4.30 % after ozone-assisted bleaching was achieved with effective separation of synthetic fibers from the post-consumer textile waste. Additionally, ozonation post-treatment enhanced CNCs' purity by effectively removing dye residues without the need for harsh chemicals addition. This process was also applied to the post-hydrolysis acid to increase acid reusability. Comprehensive physicochemical characterizations confirmed the nanocrystalline morphology of the extracted CNCs and indicated subtle structural changes after ozonation. The proof-of-concept application potential of the extracted CNCs was demonstrated in selective cationic dye adsorption and oil-water separation. The CNCs composite filter paper exhibited successful selective removal of cationic dyes and achieved a demulsification efficiency of 85.54 % in oil-water separation, highlighting their efficacy in sustainable wastewater treatment.