Lignosulfonates Enable the Coproduction of Fibrillated Lignocellulose and Fermentable Sugars from Chemi-Thermomechanical Wood Fibers

Lignosulfonates (LS) are known to reduce the recalcitrance of wood fibers to enzymatic hydrolysis. This study furthers the use of LS for the bioconversion of chemi-thermomechanical pulp (CTMP, ca. 26% lignin) at high solids content (10%) using a cellulase and hemicellulase prehydrolysis complex combined with LS loading (dual treatment). The process (10% solids, 12 h) increases the sugar yield by 20% and produces high-quality lignin-containing cellulose nanofibrils (LCNF) by mechanical fibrillation. Moreover, the dual treatment yields nanofibrils of smaller lateral size and enables better colloidal stability compared with those obtained by enzyme treatment alone or by sequential application (LS addition after enzyme). Translucent films were produced with LCNF, which are shown for their reduced hydrophilicity, high mechanical strength, and UV shielding performance. The introduced approach for efficient utilization of lignocellulose resources to coproduce high-value fibrillated lignocellulose and sugars is expected to lead to new opportunities given the availability of CTMP under the persistent reduction in demand of newsprint and printing grades.