From trash to wealth: integrated production of second-generation ethanol, xylooligosaccharides and lignin nanoparticles

The integration of different biorefinery platforms – combining the production of second-generation ethanol, xylooligosaccharides and lignin nanoparticles from various lignocellulosic biomasses (elephant grass, sugarcane bagasse, pine, eucalyptus, and grape stalk) – was evaluated. After pretreatment, the biomasses were subjected to enzymatic hydrolysis. Liquors from both the hydrothermal pretreatment and enzymatic hydrolysis were fermented to ethanol, reaching maximum yields of 14.20 g/L (for hydrothermal grape stalk liquor) and 8.37 g/L (for eucalyptus enzymatic hydrolysate). Following fermentation, these same liquors were analyzed for their xylooligosaccharide content. The enzymatic hydrolysate yielded more xylooligosaccharides (5.13 mg/g of sugarcane bagasse) than the liquor from hydrothermal pretreatment (1.32 mg/g of grape stalk). The resulting enzymatic lignins exhibited good UVB absorption, specially from sugarcane bagasse. Additionally, eucalyptus lignin demonstrated higher antioxidant activity. Finally, the enzymatic lignins were converted into lignin micro- and nanoparticles (Ø = 100 – 500 nm, for sugarcane bagasse), with distinct morphologies.