SONO-CHEMICAL PREPARATION OF CELLULOSE NANOWHISKERS FROM &ITLUFFA CYLINDRICA&IT FIBERS OPTIMIZED BY RESPONSE SURFACE METHODOLOGY

摘要

An attempt to optimize the sono-chemical processing for cellulose nanowhiskers (CNWs) from Luffa cylindrica has been reported. Response surface methodology was applied to describe the influence of sulfuric acid concentration, temperature and sonication time on the yield of CNWs using the Box-Behnken experimental design. The sulfuric acid concentration of 62 wt%, temperature of 51 degrees C, and sonication time of 46 min were the optimal conditions for preparing CNWs via low-intensity ultrasound-assisted acid hydrolysis. The CNW yield reached 93.6% at the optimal combination of parameter settings and the value was well within the range predicted by the model, while the yield was only 72.1% in the absence of ultrasonic treatment. TEM observation revealed that CNWs obtained from ultrasound-assisted hydrolysis and conventional hydrolysis was very similar in rod-like micro-morphology with widths and lengths of 10-20 and 100-300 nm, respectively. XRD analysis indicated that both CNW samples presented cellulose I crystal structure with a Segal crystallinity index of 68.7% for ultrasound-assisted hydrolysis and 73.4% for conventional hydrolysis. These results suggest that low-intensity ultrasound-assisted acid hydrolysis could be a recommendable option for the high-yield production of uniform nanosized CNWs from Luffa cylindrica with high crystallinity and good dispersion stability at industrial level.