Characterization of distinct types of isolated lignins from industrial waste and their potential use calorific

The replacement of fossil fuels with alternative energy sources has proven to be a promising approach to reducing greenhouse gas emissions. In this context, agro-industrial residues serve as an important source to produce new materials, chemicals, or energy. One of the advancements in recent technologies applied in biorefineries is focused on the valorization of lignin for bioenergy production and the development of new products. This article aims to analyze and characterize distinct types of lignins isolated from four Brazilian agro-industrial residues: sugarcane bagasse, black liquor from cellulose pulp, mango seed, and pineapple peel. The focus is on the thermal and structural characterization of the samples through energy content analysis, TGA, DSC, UV-Vis, SEM, FT-IR, and elemental analysis. All of them demonstrated high potential for caloric and energy use, considering their high SCP (Superior Calorific Power) and carbon content in their compositions, which increases the profitability of bioenergy production. However, particular emphasis is given to lignin isolated from sugarcane bagasse and eucalyptus due to their wide availability as industrial residues, easy access for use, and the large quantity of unused waste and improper disposal, suggesting further studies for their applications.