Physicochemical characterization of residue from the enzymatic hydrolysis of sugarcane bagasse in a cellulosic ethanol process at pilot scale

Abstract

One of the major obstacles to use lignin as feedstock for value-added products at industrial scale is that its physicochemical characteristics can widely vary. Thus, it is necessary to know such characteristics before applying in the synthesis of products. In this study, we produce a lignocellulosic biomass in pilot scale composed of lignin (47%w/w) and cellulose fibers (40%w/w). This biomass was obtained from the enzymatic hydrolysis of sugarcane bagasse that was pretreated by a hydrothermal process (190°C/10min). After obtaining this residue, which is listed here as “Enzymatic Hydrolysis Residue Lignin” (EHRL), its physicochemical and thermal characterization was performed. A highly concentrated lignin from the LignoBoost process in Kraft pulp mill, lignin LignoBoost (LBL), was also evaluated in order to compare it with the EHRL. The C9-formulae of the lignin extracted from the EHRL is C9.0H11.2O4.3S0.08N0.17(OCH3)0.9(OHphenolic)0.7(OHaliphatic)0.6 and the C9-formulae of the LBL is C9.0H7.9O1.4S0.16N0.01(OCH3)1.1(OHphenolic)0.7(OHaliphatic)0.5. By the 2D Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC) technique, syringyl/guaiacyl ratios for the EHRL and the LBL are 1.8 and 4.8, respectively. Thus, the EHRL appears to be promising for phenolic composite, for instance, since it has lower methoxyl content. The EHRL showed larger range of fiber particle sizes (<4.05mm–0.4μm) than the LBL (0.4–1090μm).