Energy-efficient fabrication of lignin-containing microfibrillated cellulose via high-consistency alkali kneading

Although microfibrillated cellulose (MFC) has attracted considerable attention as a sustainable alternative to petroleum-based polymers, its large-scale production remains constrained owing to the high energy requirement of mechanical fibrillation. This study presents an energy-efficient approach to producing lignin-containing MFC (L-MFC) from organosolv pulp (OP) via a high-consistency, dough-like alkali-kneading pretreatment. Lengths of the lignocellulose fibers derived from OP were relatively short, which is advantageous for subsequent mechanical fibrillation. Using L-MFC C prepared via 15 wt% high-concentration alkali kneading pretreatment (Method C) reduced energy consumption by up to 35% and shortened homogenization processing time by approximately 32% relative to the other methods. The L-MFC C five-pass film, despite its high residual lignin content, exhibited a tensile strength comparable to that of a commercial enzymatically pretreated cellulose nanofibril film processed through ten homogenization passes. In addition, this L-MFC film possessed good barrier properties against oxygen and water vapor. This suggests that the proposed pretreatment method provides a route to economically and feasibly produce L-MFC and is expected to be applied in the development of sustainable bio-based packaging materials.