Lignin recovery from a mixture of SIX lignocellulosic biomasses within a biorefinery scheme based on a sequential process of autohydrolysis and organosolv

Abstract

A mixture of six lignocellulosic biomasses could be a solution for sustainable biorefinery supply throughout the year compared with seasonal feedstock. In this study, a sequential process of autohydrolysis and organosolv was used for this mixture. To optimize lignin extraction, an experimental design was used to study the impacts of temperature, ethanol concentration, and time on lignin yield and related characteristics of the organosolv process. A highly pure organosolv lignin (OL) (ca. 90% Klason lignin) was recovered. FTIR analysis showed the main lignin structure was almost unchanged. NMR confirmed this and revealed the presence of guaiacyl-syringyl type with small amounts of p-hydroxyphenyl units (25% G, 70% S, and 5% H), predominantly presenting β-O-4 units (ca. 80%). Tg from 73 to 85 °C was detected. OL showed radical scavenging activity as high as the commercial antioxidant BHT. Moreover, enzymatic susceptibility of delignified biomass was accessed, in which 50% glucose yield was achieved.