Enhanced enzymatic saccharification of kenaf powder after ultrasonic pretreatment in ionic liquids at room temperature

• Published in: Bioresource technology 2012-01, Vol.103 (1), p.259-265
• Main Authors: Ninomiya, Kazuaki, Kamide, Kazuki, Takahashi, Kenji, Shimizu, Nobuaki
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biotechnology; Biotechnology - methods; Carbohydrate Metabolism - drug effects; Cellulase - metabolism; Cellulose; Cellulose - analysis; Chlorides; Crystallization; Enzymatic hydrolysis; Fundamental and applied biological sciences. Psychology; Glucose; Hibiscus - drug effects; Hibiscus - ultrastructure; Hydrolysis; Hydrolysis - drug effects; Imidazoles - pharmacology; Ionic liquid; Ionic liquids; Ionic Liquids - pharmacology; Kenaf; Lignin - analysis; Lignocellulose; phosphates; Polysaccharides - analysis; Powders; Pretreatment; Saccharification; Spectroscopy, Fourier Transform Infrared; Temperature; Time Factors; Ultrasonic pretreatment; Ultrasonics; X-Ray Diffraction
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2011.10.019

► Ultrasonic pretreatment of lignocellulose in ionic liquids is suggested. ► This was more efficient than the existing thermal pretreatment in ionic liquid. ► Sixty to ninety-five percentage of cellulose in kenaf powder was hydrolyzed to glucose after the pretreatment. This study demonstrates for the first time that the enzymatic hydrolysis of cellulose is drastically enhanced following ultrasonic pretreatment of lignocellulosic material in ionic liquids (ILs) when compared to conventional thermal pretreatment. Five types of ILs, 1-buthyl-3-methylimidazolium chloride (BmimCl), 1-allyl-3-methylimidazolium chloride (AmimCl), 1-ethyl-3-methylimidazolium chloride (EmimCl), 1-ethyl-3-methylimidazolium diethyl phosphate (EmimDep), and 1-ethyl-3-methylimidazolium acetate (EmimOAc) were tested. Cellulose saccharification ratio was about 20% for kenaf powders pretreated in BmimCl, AmimCl, EmimCl, and EmimDep by conventional heating at 110°C for 120min. Conversely, 60–95% of cellulose was hydrolyzed to glucose, subsequent to ultrasonic pretreatment in the same ILs for 120min at 25°C. The cellulose saccharification ratio of kenaf powder in EmimOAc was 86% after only 15min of the ultrasonic pretreatment at 25°C, compared to only 47% in that case of thermal pretreatment in the IL.