A co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals from ball-milled woods

Abstract

This study demonstrated the technical potential for the large-scale co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals. Ball-milled woods with two particle sizes were prepared by ball milling for 80min or 120min (BMW₈₀, BMW₁₂₀) and then enzymatically hydrolyzed. 78.3% cellulose conversion of BMW₁₂₀ was achieved, which was three times as high as the conversion of BMW₈₀. The hydrolyzed residues (HRs) were neutrally sulfonated cooking. 57.72g/L and 88.16g/L lignosulfonate concentration, respectively, were harvested from HR₈₀ and HR₁₂₀, and 42.6±0.5% lignin were removed. The subsequent solid residuals were purified to produce cellulose and then this material was acid-hydrolyzed to produce cellulose nanocrystals. The BMW₁₂₀ maintained smaller particle size and aspect ratio during each step of during the multiple processes, while the average aspect ratio of its cellulose nanocrystals was larger. The crystallinity of both materials increased with each step of wet processing, reaching to 74% for the cellulose.

Keywords: Aspect ratio; Cellulose; Cellulose nanocrystals; Co-production; Crystallinity; Lignosulfonates; Mass balance; Particle size; Sugars.