In this study, cellulose fibers were removed from crop by-products using a combination of sodium hydroxide treatment
followed by acidified sodium chlorite treatment. The objective was to obtain high recovery of cellulose by optimizing treatment conditions with sodium hydroxide (5–20%, 25–75 °C and 2–10 h) followed by acidified sodium chlorite (1.7%, 75 °C
for 2–6 h) to remove maximum lignin and hemicellulose, as well as to investigate the effect of lignin content of the starting
materials on the treatment efficiency. Samples were characterized for their chemical composition, crystallinity, thermal
behavior and morphology to evaluate the effects of treatments on the fibers’ structure. The optimum sodium hydroxide
treatment conditions for maximum cellulose recovery was at 15% NaOH concentration, 99 °C and 6 h. Subsequent acidified
sodium chlorite treatment at 75 °C was found to be effective in removing both hemicellulose and lignin, resulting in higher
recovery of cellulose in lupin hull (~ 95%) and canola straw (~ 93%). The resultant cellulose fibers of both crop by-products
had increased crystallinity without changing cellulose I structure (~ 68–73%). Improved thermal stabilities were observed
with increased onset of degradation temperatures up to 307–318 °C. Morphological investigations validated the effectiveness of treatments, revealing disrupted cell wall matrix and increased surface area due to the removal of non-cellulosics.
The results suggest that the optimized combination of sodium hydroxide and acidified sodium chlorite treatments could be
effectively used for the isolation of cellulose fibers from sweet blue lupin hull and canola straw, which find a great number
of uses in a wide range of industrial applications.

• Cellulose Fiber Isolation and Characterization from Sweet Blue Lupin Hull and Canola Straw