Production of cellulose nanofibers and sugars using high dry matter feedstock

Abstract

Sugars are a sustainable platform for producing chemicals and polymers, while cellulose nanofibers (CNF) are sustainable materials with high specific mechanical properties that have an important role to play in many applications. This study highlights the feasibility of producing sugars and CNF using high dry matter (DM) content of 20 %. A commercial enzyme cocktail at low dosage, 5 mg EP/g DM, and a high 15 mg EP/g DM, were used to hydrolyze the pulp cellulose to produce sugars and CNF. HPLC was used to evaluate the cellulose conversion rate and amount of sugar realized. The CNF were studied using TEM, the diameter of the CNF were measured and estimate the crystallinity. The cellulose conversion plateaued at about 48 h for both the low and high dosage, indicating inhibition due to higher sugar concentration and/or increased recalcitrance of the remaining CNF. The CNF obtained at low enzyme indicated the fibrils were insufficiently separated. At the high dosage, less clumps were observed and with smaller diameter than with the low enzyme dosage. The high dosage also produced CNF with significantly higher crystallinity index, confirming that amorphous cellulose portions readily underwent enzymatic hydrolysis and left more recalcitrant CNF.