Highly efficient and green micro/nano cellulose preparation with micro-nano bubbles from mild alkali pretreated bagasse

Cellulose extraction accounts for 70% of the total production cost required for the preparation of micro/nano cellulose. Conventional pretreatment methods cause equipment corrosion and generate non-recyclable waste liquids. Thus the industrial-scale preparation of micro/nano cellulose is limited. To overcome this limitation, herein, a method is proposed, where in a mild alkaline pretreatment is combined with the micro-nano bubble (MNB) treatment, for the extraction of cellulose from bagasse. A delignification rate of > 92% was attained, micro/nano cellulose was exposed on the pulp surface owing to the MNB treatment; the 4-h MNB treatment resulted in the complete exposure of micro/nano fibers. The production cost for this process was only 3.19 USD/kg of CNFs, about 70.9 times lower than that of TEMPO oxidation. An appropriate MNB treatment time (1 h, 2 h) allowed the retention of moderate micro-fibers, which enhanced the maximum tensile force and tensile strength of micro/nano cellulose paper by about 50%. The results revealed that the proposed method serves as an efficient, green, and sustainable strategy for the large-scale and low-cost production of micro/nano cellulose.