Optimising cellulose nanofiber extraction from water hyacinth (Eichhornia crassipes) stems: Effects of steam explosion pretreatment and ultrasonication time

This study presents a highly efficient approach to isolate high-quality cellulose nanofibers (CNFs) from water hyacinth. The researchers employed a synergistic combination of steam explosion pretreatment and optimised ultrasonic fibrillation. The steam explosion pretreatment effectively disrupted the lignocellulosic structure, enhancing subsequent chemical and mechanical processing steps. Ultrasonic fibrillation for 1, 2, and 3 h yielded CNFs with average diameters of 24.3 nm, 12.05 nm, and 8.9 nm, respectively. The cellulose yield was 43.2 % from the steam-exploded sample, with 92–98 % CNF recovery. Comprehensive analyses revealed that the steam explosion pretreatment substantially improved the dispersion stability, crystallinity index (71 %), and the thermal stability (304 °C) of the CNFs as compared to the untreated fibres. The optimised chemical treatment further enhanced the CNF properties by removing lignin and hemicellulose components. The 1 h ultrasonic fibrillation of steam-exploded cellulose demonstrated superior efficiency, outperforming previous studies without pretreatment. Prolonged fibrillation had minimal impact on the CNF characteristics. This synergistic approach provides a highly effective and efficient method for isolating premium-quality CNFs from water hyacinth, with exceptional physical and thermal properties for advanced materials and composites. These findings pave the way for further exploration of water hyacinth-derived CNF's industrial potential.