Enzymatic hydrolysis of ionic liquid-pretreated celluloses: Contribution of CP-MAS 13C NMR and SEM

• Published in: Bioresource technology 2011-08, Vol.102 (15), p.7335-7342
• Main Authors: Husson, Eric, Buchoux, Sébastien, Avondo, Carine, Cailleu, Dominique, Djellab, Karim, Gosselin, Isabelle, Wattraint, Olivier, Sarazin, Catherine
• Format: Article
• Language: English
• Subjects: Carbon Isotopes; Cellobiose - biosynthesis; Cellulase - metabolism; Cellulase from Trichoderma reesei; Cellulose; Cellulose - chemistry; Cellulose - metabolism; Cellulose - ultrastructure; Cellulose fibers; Chemical Sciences; Crystallinity; Crystallization; Glucose; Glucose - biosynthesis; Hydrolysis; Hydrolysis - drug effects; Ionic liquid; Ionic liquids; Ionic Liquids - pharmacology; Kinetics; Magnetic Resonance Spectroscopy; Microscopy, Electron, Scanning; Nuclear magnetic resonance; Pretreatment; Scanning electron microscopy; Substrate Specificity - drug effects; Supramolecular structure; Time Factors; Trichoderma - enzymology
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2011.04.097

[Display omitted] ► [Emim]+[MeO(H)PO2]− is a suitable solvent for cellulose pretreatment. ► Reduced glucose production after 24h is concomitant with cellobiose consumption. ► The efficiency of cellulose degradation could not be exclusively linked to the CrI. ► SEM shows a total loss of fiber organization which correlates with the high yields. The supramolecular structure of four model celluloses was altered prior to their enzymatic saccharification using two ionic liquid pretreatments: one with the commonly used 1-ethyl-3-methylimidazolium acetate ([Emim]+[CH3COO]−) and the other with the newly developed 1-ethyl-3-methylimidazolium methylphosphonate ([Emim]+[MeO(H)PO2]−). The estimation of crystallinity index (CrI) by solid state 13C nuclear magnetic resonance for each untreated/pretreated celluloses was compared with the performances of their enzymatic hydrolysis. For α-cellulose, both pretreatments led to a significant decrease in CrI from 25% to 5% but had no effect on glucose yields. In contrast, The [Emim]+[MeO(H)PO2]− pretreatment on the long fibers of cellulose had no significant effect on the CrI although a conversion yield in glucose of 88% is obtained versus 32% without pretreatment. However, scanning electron microscopy analysis suggested a loss of fiber organization induced by both ionic liquid pretreatments leading to a larger accessibility by cellulases to the cellulose surface.