(413a) Codesign of Combinatorial Organosolv Pretreatment (COP) and Lignin Nanoparticles (LNPs) in Biorefineries

Sustainable biorefinery of lignocellulosic biomass to usable platform molecules for producing a broad and multifunctional array of value-added products are key to achieving a green biobased economy. Given the accessibility of lignin, the second-most abundant organic polymer, efforts are underway to valorize lignin to value-added products to make a sustainability of biorefineries Despite various efforts, lignin valorization is still hindered by the poor fractionation performance and the low reactivity due to its inherent heterogeneity, which is highly sensitive to the fractionation approach employed. To address these challenges and make biorefineries sustainable, codesign of fractionation technologies and lignin valorization has been found to be essential. Combinatorial organosolv pretreatment (COP) was thus developed in an effort to efficiently produce sugars and improve lignin processability for the fabrication of lignin nanoparticles (LNPs). COP produced greater than a 90% glucose yield and 73% xylose yield, suggesting the improved sugar release from biomass. The lignin with specific reactivity fractionated from each COP was subsequently used to fabricate lignin nanoparticles (LNPs) via antisolvent precipitation. The smallest effective diameter (142 nm) of LNPs was obtained from COP using EtOH plus sulfuric acid. These LNPs possessed a lower polydispersity index and higher zeta potential, suggesting superior uniformity and greater stability. The lignin characterization results indicated that COP using EtOH plus sulfuric acid cleaved more β-O-4 and β–β linkages and produced lignin with a higher molecular weight and increased G-lignin and C5-substituted OH contents, suggesting the generation of condensed lignin. These modifications enhanced the hydrophobic interactions between lignins and thus enabled the fabrication of LNPs with a small particle size. COP using EtOH plus sulfuric acid also enriched total phenolic OH content and could promote the formation of a hydrogen-bonding network within LNPs. Together with a high zeta potential due to the increased phenolic OH and COOH groups, the stability of LNPs was thus enhanced. Overall, COP increased the sugar release from biomass and improved the lignin processability to facilitate the design of LNPs with satisfactory properties. Fabrication of LNPs in biorefineries will also open up a green and sustainable route to upgrade the lignin stream for lignin valorization and thus showed the potential to improve the sustainability of biorefineries.