Technical kraft lignin from coffee parchment

Abstract The biomass deconstructed by kraft process and the lignin dissolved in the black liquor are burned to generate energy in a pulp mill. This study used the black liquor from coffee parchment cooking, a residue from the coffee industry, to isolate kraft technical lignin. The parchment was subjected to the kraft pulping process to obtain pulps of kappa number 60 and 25, and the resulting black liquors were used for lignin extraction. Chemical characterization, elemental analysis and heating value of liquors and lignins were performed, as well as FTIR and Py-CG-MS analysis of lignins. The cooking provided liquors with similar characteristics, with lignin content of 31.67 and 32.63% for kappa 60 and 25 liquors, respectively. The extractions resulted in high purity lignin (92.35% for K#60 lignin and 93.96% for K#25 lignin). The higher heating values were 23.8 and 25.4 MJ/kg for K#25 and K#60 lignins, respectively. FTIR analysis showed characteristic peaks of lignin. Through Py-GC-MS, it was possible to observe the slight predominance of guaiacyl-type lignin, which can be an advantage depending on the application. It is possible to extract lignin from the black liquor obtained from the coffee parchment pulping to generate products with high-added value.