Extraction and Characterization of Lignin from Corn Straw (Zea mays L.)

Brazil, as one of the largest corn producers in the world, annually generates large quantities of lignocellulosic residues, which have little added value after harvest. This study aimed to extract the lignin from corn straw by alkaline pulping, using as solvent an aqueous solution of NaOH (97%), as well as its characterization by FT-IR in the range between 400-4.000 cm(-1), H-1 NMR operating at 600 MHz, SEM, and EDS at 5 kV, and Thermogravimetric analysis between 25-800 degrees C. The extracted sample showed characteristic lignin spectra, in which the presence of hydroxyl groups and carboxylic groups. Typical aromatic rings of GSH lignin were verified. We observed a structure with a predominance of straight and slightly rounded regions. In the mineralogical composition, the elements carbon and oxygen were identified, in addition to the residual presence of sodium. Three thermal degradation stages were observed, which were related to moisture loss, lignin pyrolysis, and aromatic rings degradation, respectively, confirming its thermal stability.