Preparation of Lignin Nanoparticles from Wood Waste for Wood Surface Treatment

Lignin was isolated from wood wastes comprising Iroko sawdust (IR) and mixed sawdust from Iroko and Norway spruce (IRNS), furnished by a local wood houses producer. The respective acidolysis lignin fractions were structurally characterized using pyrolysis (Py)-GCMS, two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance (2D HSQC NMR), Fourier-transform infrared FTIR and ultraviolet-visible (UV-VIS) spectroscopies, size exclusion chromatography, and standard wet-chemistry methods for Klason lignin and polysaccharides determination. The isolated lignin fractions were subsequently used for the preparation of lignin nanoparticles (LNPs) using a non-solvent method. LNPs were then used for wood surface treatment using a dip-coating technique. The coated wood samples were analyzed by colorimetry and scanning electron microscopy (SEM) before and after artificial weathering experiments in a UV chamber to investigate the UV protection potential of the LNPs coatings. Wood samples dip-coated with LNPs showed promising surface modifications resembling a sort of film of fused LNPs. Coatings made from IR-LNPs and IRNS-LNPs performed significantly better in artificial weathering experiments than uncoated reference samples.