Abstract
Valorization of lignin is essential for the success of emerging lignocellulosic biorefineries. Additional valorization of non-cellulosic forest resources can also generate secondary revenue streams helpful for their sustainable operation. Toward these goals, lignins recovered from hot- water extracts of angiosperms produced at pilot scale (sugar maple, willow, miscanthus, wheat straw, mixed angiosperms) were characterized and further fractionated to generate fractions with distinct physicochemical properties. The recovered and fractionated lignins were used in synthesis of lignin-acrylamide-kaolin (10.7% w/w total lignin) and lignin-poly(ethylene glycol) diglycidyl ether (PEGDGE) gels (66.7 w/w total lignin). Lignin-acrylamide-kaolin gels were suitable for adsorption-based applications (removal of dye and metallic cations from aqueous solutions), while lignin-PEGDGE gels were suitable for absorption-based applications (absorption and release of fragrances and bioactive solutions). Two types of fractionation were found to influence gel properties differently, demonstrating the importance of lignin-to-carbohydrates ratio in the produced fraction on the hydrogel architecture. The methanolic and aqueous extracts of chaga mushroom (a non-lignocellulosic forest biomass) were found to have viable antioxidant properties. The hot-water extracts of chaga were further used in green synthesis of chaga-silver nanoparticles, expected to have bioactive properties. Lignin-PEGDGE gels were found to be good carriers for the delivery of these nanoparticles.