Improved chemical reactivity of lignocellulose from high solids content defibrillation by twin-screw extrusion

Abstract

The low reactivity of lignocellulose limits the effective chemical conversion of lignocellulose biomass into functional bioproducts. Conventional wet micro-fibrillation using a grinder or homogenizer can improve the chemical accessibility of lignocellulose but has limited productivity for industry by the low processing solids content. The presented work demonstrates fibrillation of lignocellulose at high solids content up to 70 wt% can be achieved by a pilot-scale twin-screw extruder. Morphological characterizations of the extruded lignocellulose show that twin-screw extrusion can effectively fibrillate the wood pulp into submicron fibrils, and the degree of fibrillation is enhanced by operating at higher solids content, making for an economical process. The treated wood pulp presents 2.08 and 4.8 times higher water retention capacity and specific surface area, respectively, as compared with the original material, thus opening the cell wall structure for improving chemical accessibility. Acetylation results show that twin-screw extrusion pre-treatment can significantly accelerate the chemical modifications of lignocellulose by 50% and reduce chemicals usage. This method for micro-fibrillating lignocellulose shows high reported consistency and should be of great interest to the bioplastics industry.