Evaluation of Lignin Extraction Using Different Routes after Hydrothermal Treatment

Abstract

Hydrothermal and enzymatic hydrolysis processes are concepts for applications in biorefineries commonly used in the pulp and cellulose industries to improve the removal of hemicelluloses, optimizing the cellulose content in product. However, the same procedures can be used to increase the lignin isolation from lignocellulosic biomass. Thus, this study aimed to analyze the extraction of lignin from two Brazilian tree biomasses through different extraction sequences. Sawdust from Joannesia princeps Vellozo (B1) and Astronium concinnum (Engl.) Schott (B2) were used. The route1 use a lignin extraction with acetone (AEL) after the autohydrolysis step, and route 2 included an enzymatic hydrolysis step prior to the extraction (EAEL). Both routes adopted two distinct hydrothermal treatment (HTT) severities reaction (P-factor 800 and 2000). Chemical characterization analysis was done in the original biomass and in the solids generated by the reaction steps. The route 1 promoted higher lignin efficiency removal in both biomasses at P-factor 2000, with 76% AEL in B1, and 43% in B2. The EH sequence adopted in route 2 did not significantly impair the lignin extraction. The Joannesia princeps Vellozo (B1) presented better results in both extraction routes, but in route 1 the efficiency in lignin removal (AEL) was greater at higher severities (P-factor 800), which can be related to biomass properties. The inclusion of EH sequence after HTT, studied in route 2, did not result in higher removal efficiency of lignin (EAEL) for the two studied biomasses.

Keywords: autohydrolysis, biorefinery concept, Brazilian hardwood residues.