Lignin is part of the lignocellulosic biomass found in hardwoods, softwoods and herbaceous plants, such as wheat straw. It is isolated by fractionation and pulping processes, where it is considered a waste product and is currently mainly burned to generate electricity and heat. However, lignin is a biopolymer containing large amounts of aromatic compounds and is thus a potential source for many chemicals of significant value. The main processes for its valorisation require dissolution in organic solvents. This step may affect the mass balance of the entire process and the chemical structure of the biopolymer, as lignins are rarely completely soluble in organic solvents. The thesis was focused on the dissolution of two commercial kraft lignins derived from softwood and hardwood. Lignin samples were treated using different green organic solvents, measuring the soluble and insoluble content to determine the mass balance and using chemical structure characterisation using the FTIR technique.
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