Production of cellulose nano/microfibers through simultaneous milling and enzymatic hydrolysis with an optimized cocktail of cellulase/xylanase/LPMO

Abstract

Cellulose nanofibers (CNF) and microfibrillated cellulose (MFC) are biodegradable micro and nanomaterials derived from plant cellulose. The properties of CNF, influenced by fibril length, impact the strength of cellulose-based nanomaterials. This study uses enzymatic milling to explore pretreatments, enzymatic optimization, and CNF/MFC production. The study found that hammer milling and lamination are effective pretreatments for preserving fibers. The optimal enzymatic mixture contained 75 % cellulase and 25 % xylanase, yielding 68.7 % and 2.86 %/h productivity, respectively. The addition of the LPMO enzyme increased the yield by 10–13 %, depending on its concentration. Enzymatic milling was introduced as an innovative approach to CNF production, reducing hydrolysis time and creating milder processing conditions. The combined process of ball milling and enzymatic hydrolysis on pre-ground pulp in the hammer mill achieved a maximum CNF yield of 45.83 % and productivity of 13.10 %/h. X-ray diffraction showed that the lamination-pre-treated pulp had a high crystallinity index of 84.34 %. Scanning electron microscopy revealed fibers with diameters ranging from 52 nm to 296 nm. These findings support the search for sustainable and eco-friendly alternatives to non-renewable resources, enabling sustainable CNF production at room temperature with reduced processing time.