Ozone pretreatment facilitating cellulase hydrolysis of unbleached bamboo pulp for improved fiber flexibility

In this study, an integrated and feasible approach by combining ozone pretreatment and cellulase hydrolysis of unbleached bamboo kraft pulp (UBKP) to improve the fiber flexibility was proposed. Ozone was utilized as green facilitator of cellulase treatment for increased enzyme accessibility and improved fiber flexibility by removing lignin and particle carbohydrates. Ozone was found to decrease the fiber stiffness and reduce the lignin content of UBKP fibers from 14.46 wt% to 9.96 wt%. The DP of UBKP was also decreased to 1210 after ozone-cellulase treatment, with a reduced carboxyl content of 0.064 mmol/g. The flexibility of UBKP fibers treated by ozone-cellulase system was 34.68 × 1014/(N·m2), which was 7 times higher than that of the original UBKP fibers. This study put forward a practical and sustainable approach to improve the flexibility of UBKP fibers, and to further study the possibility of ozone oxidation chemistry in cellulase hydrolysis process, thus would further broaden the high-value application of UBKP and ozone technology in tissue paper production. [Display omitted] •Ozone oxidation can soften the compact structure of bamboo fibers by removing lignin.•Cellulase treatment can be facilitated by ozone pretreatment for higher fiber flexibility.•Ozone treatment acts as effective approach to improve fiber flexibility.