Anatomical and compressive characterization of Cryptomeria japonica hydrolyzed with phosphoric acid for lignin residue utilization

• Published in: Journal of materials science 2023-07, Vol.58 (28), p.11680-11696
• Main Authors: Kurei, Tatsuki, Hirano, Seiya, Nakaba, Satoshi, Funada, Ryo, Horikawa, Yoshiki
• Format: Article
• Language: English
• Subjects: Acids; Analysis; Anisotropy; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Composites & Nanocomposites; Compressive strength; Crystallography and Scattering Methods; Densification; Density; Hydrolysis; Infrared analysis; Infrared spectra; Lignin; Materials Science; Phosphates; Phosphoric acid; Polymer Sciences; Polysaccharides; Principal components analysis; Residues; Solid Mechanics
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-023-08753-4

The handling of lignin residues is a concern for the use of wood in biorefineries. This study proposes a new pathway for lignin residues that uses the structure of wood. Optimal phosphoric acid hydrolysis to remove polysaccharides was selected from the principal component analysis based on infrared spectra. Acid-hydrolyzed wood, the lignin residue, exhibited anisotropic shrinkage, but its anatomical structure was not fractured. The strength and modulus of the lignin residue varied with the compression direction, reflecting the anisotropic structure of the wood that was not fractured by acid hydrolysis. The density of the lignin residue initially decreased and then slightly increased during ten cycles of 5 wt% phosphoric acid hydrolysis at 180 °C for 1 h, resulting in minor recovery of the modulus and strength. Therefore, practical durability can be achieved by increasing the density of the lignin residue through densification or combination with other functional polymers. Thus, simpler top-down strategies are expected compared with the currently proposed bottom-up approach for lignin. Graphical abstract