Process for fractionating lignocellulosics
Abstract:
A method for the isolation of lignin from a lignocellulosic biomass, comprising providing a lignocellulosic biomass; extracting sugar free lignin from the lignocellulosic biomass by contacting said biomass with an organic aqueous solution comprising water and at least one water miscible organic solvent, either discontinuously or continuously, whereby a biomass-solvent suspension is formed; separating the sugar free lignin solution from the biomass-solvent suspension to obtain a sugar free lignin solution and a cellulosic material enriched with lignin carbohydrate complexes and hemicellulose, and optionally isolating sugar free lignin from the sugar free lignin solution; extracting the lignin carbohydrate complexes from the cellulosic material enriched with lignin carbohydrate complexes and hemicellulose by contacting said cellulosic material with a liquid comprising at least water, whereby treated biomass suspension is formed; separating the lignin carbohydrate complexes solution from said treated biomass suspension to obtain a lignin carbohydrate complexes solution and cellulosic material enriched with hemicellulose, and, optionally isolating lignin carbohydrate complexes from the solution obtained and isolating further sugar free lignin from the mother liquor of said lignin carbohydrate complexes isolation, optionally after combining the mother liquor of said lignin carbohydrate complexes isolation with the sugar free lignin solution obtained from extracting sugar free lignin from the lignocellulosic biomass.
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