Highly effective fractionation chemistry to overcome the recalcitrance of softwood lignocellulose

Juho Antti Sirviö; Marja Mikola; Juha Ahola; Juha P Heiskanen; Svitlana Filonenko; Ari Ämmälä

doi:10.1016/j.carbpol.2023.120815

Highly effective fractionation chemistry to overcome the recalcitrance of softwood lignocellulose

Carbohydr Polym. 2023 Jul 15:312:120815. doi: 10.1016/j.carbpol.2023.120815. Epub 2023 Mar 16.

Authors

Juho Antti Sirviö¹, Marja Mikola², Juha Ahola², Juha P Heiskanen³, Svitlana Filonenko⁴, Ari Ämmälä⁵

Affiliations

¹ Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland. Electronic address: juho.sirvio@oulu.fi.
² Chemical Process Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland.
³ Research Unit of Sustainable Chemistry, University of Oulu, P.O. Box 4300, FI-90014 Oulu, Finland.
⁴ Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany.
⁵ Fibre and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland.

PMID: 37059543
DOI: 10.1016/j.carbpol.2023.120815

Abstract

The efficient fractionation and thus production of individual biomass components are pivotal processes in the biorefinery concept. However, the recalcitrant nature of lignocellulose biomass, especially in the case of softwood, is one of the main obstacles to the wider application of biomass-based chemicals and materials. In this study, the use of aqueous acidic systems in the presence of thiourea was studied for the fractionation of softwood in mild conditions. Despite relatively low temperature (100 °C) and treatment times (30-90 min), notable high lignin removal efficiency (approximately 90 %) was obtained. Chemical characterization and the isolation of minor fraction of cationic, water-soluble lignin indicated that the fractionation proceed via nucleophilic addition of thiourea to lignin, resulting in dissolution of lignin in acidic water in relatively mild conditions. Besides high fractionation efficiency, both fiber and lignin fractions were obtained with bright color, significantly elevating their usability in material applications.

Keywords: Fractionation; Lignin; Lignocellulose; Softwood; Thiourea.