Lignin recovery from spent liquors of sugar cane bagasse ethanol- water fractionation

FELISSIA, FERNANDO; VALLEJOS M.E.; AREA, MARIA CRISTINA

CELLULOSE CHEMISTRY AND TECHNOLOGY

Romanian Academy

Año: 2010 vol. 44 p. 311 - 318

0576-9787

The aim of the present work was to find the most adequate method of lignin recovery from two spent liquors from ethanol-water fractionations catalyzed with sulfuric acid. Different methodologies to separate lignin from liquors were assessed, based on the dilution and/or evaporation of the solvent. The carbohydrates, organic acids, ethanol and degradation products content of the spent liquors were analyzed by liquid chromatography. The yield of lignin recovery was quantified. The laboratory system, represented at an industrial scale by the reduction of ethanol concentration in the spent liquors through evaporation in a flash tank to 30% v/v, dilution 1:1 at 40 ºC and centrifugation, appeared as the best alternative for lignin recovery (45% of precipitate with a purity of 94%, yielding 42% pure lignin). The second feasible procedure involvedlignin precipitation and recovery from the spent liquors by dilution with water, at room temperature. This method yielded 41% pure lignin, from a precipitate of 48% with 87% purity (much more contaminated, mainly with carbohydrates).