Métodos de extração e aproveitamento da lignina proveniente de biomassa vegetal

Abstract

Lignin is one of the most widely available biopolymers in the nature, being less abundant only when compared to cellulose. It is a three-dimensional shaped molecule, with a complex and highly branched phenolic structure. Lignin is synthesized by the enzymatic polymerization process and its structure is strongly influenced by the characteristics of the source biomass, as well as the extraction process, being the variability in the structure the main obstacle to its use. The agribusiness, with emphasis on the production of ethanol and paper, generates a large amount of biomass rich in lignin, which is used in the generation of energy or additives, since it has low value-added. The constant search for polymers, fuels and chemicals from renewable sources has driven in recent years the research for applications for lignin from lignocelullosic biomass. This work discusses the methods of extracting lignin through the pre-treatment of biomass, as the routes for transforming the extracted lignin into products with greater value-added. As the main result of this work, the four methods of extracting lignin from vegetable biomass available on the industry were analyzed: Kraft, Lignosulfonate, Soda Pulping and Organosolv, comparing their operating conditions, the molecular mass of the isolated lignin and the main chemical agents used in the process. The main routes for the synthesis of polymers from lignin available in the literature were also analyzed, being the polymers of interest Polyurethane, Lignin-Phenol-Formaldehyde (LPF), Epoxy, Polyesters, Phenolic Resins and Polyamides.