An environmentally friendly xylanase-assisted pretreatment for cellulose nanofibrils isolation from sugarcane bagasse by high-pressure homogenization

• First report to use the whiteness index to identify quality of extracted cellulose.
• Xylanase-assisted pretreatment reduced the use of NaClO2 for bleaching by 44%.
• Xylanase pre-treatment improved the crystallinity of the bleached fibers.
• An environmentally friendly method for the isolation of cellulose nanofibrils.
• Cellulose nanofibrils were isolated from bagasse by high pressure homogenization.

Cellulose nanofibrils (CNFs) from sugarcane bagasse (SCB) were isolated by high-pressure homogenization. Xylanase-assisted pretreatment after steam explosion was studied to investigate its effect on various cellulose properties such as bleaching times, reduced chemical use and color in the subsequent bleaching stage. High cellulose contents were successfully extracted from SCB with xylanase-assisted pretreatment; moreover, xylanase-treated fibers exhibited decreased bleaching times, a 44% reduction in the amount of chemicals used and had a satisfactory whiteness index compared to untreated fibers. X-ray diffraction (XRD) analysis revealed significant increases in crystallinity index for xylanase-assisted pretreatment fibers. Characterization of the fibers by scanning electron microscopy (SEM) and atomic force microscopy (AFM) indicated that the fiber diameters decreased with each treatment stage; the final CNFs obtained at 15,000 psi for 30 passes primarily ranged from 5 to 10 nm in diameter. Thermogravimetric analysis (TGA) indicated that CNFs have lower thermal stability than raw cellulose fibers. These results indicate that xylanase-assisted pretreatment with high-pressure homogenization is an environmentally friendly method to isolate CNFs and clearly demonstrates the potential of enzymatic pretreatment for reducing environmental contamination, especially with regard to toxic chlorine compounds that are required for the bleaching process.

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