(585b) Exploring the Potential of Hydrolysis Residue Lignin for the Development of Functional Bio-Based Materials

Lignin, the second most abundant biopolymer, remains underutilized primarily due to its heterogeneous structure and its propensity to undergo structural rearrangement during extraction. The majority of technical lignins are derived from the kraft pulping process, which results in a highly condensed form that poses significant challenges for subsequent utilization in the production of biochemicals and bio-based materials. Alternatively, with the growth of biorefineries (i.e., the production of biofuels and chemicals from biomass), the production of biorefinery-derived lignin is expected to increase, either through a 'lignin-first' strategy or via the valorization of lignin from the residues of enzymatic hydrolysis of pretreated biomass (hydrolysis residue lignin).

The ‘lignin-first’ strategy focuses on extracting lignin with a high content of β-O-4 linkages using various solvent systems and has received considerable attention over the past decade. In contrast, the alternative pretreatment approach that retains lignin within the biomass during processing and recovers it from hydrolysis residues after enzymatic cellulose deconstruction is still under development. In this study, the feasibility of utilizing hydrolysis residue lignin obtained through various pretreatment methods was evaluated for potential applications such as lignin-based wood adhesives, as well as fused deposition modeling (FDM) 3D printing—through thermal blending with bioplastics like polylactic acid (PLA). It was found that using mild pretreatment conditions, which avoid severe lignin condensation, provides a balance between effective cellulose hydrolysis and the production of reactive lignin suitable for various applications, offering promising insights for the design of future biorefineries.