Patent ID: 8529731

Claim:
A process for the fractionation and isolation of high α-cellulose pulp, hemicellulose (xylan) and lignin from-fibrous organic biomass wherein the organic biomass is sugarcane bagasse, said process consisting essentially of: a) saturating the organic biomass with water; b) then contacting the saturated organic biomass from step (a) with steam in a steam explosion reactor at a temperature in the range 140° C.-230° C., for period of 0.5 minute to 60 minutes, hydrolyzing and solubilizing the hemicellulose component to an extent of 70%-90%, followed by exploding the saturated biomass into fine particles of biomass by instant release of pressure, followed by evaporation of condensed water to obtain hemicellulose, c) separating and washing the fine particles of biomass with water and treating the fine particles of biomass with 10%-24% sodium hydroxide, at a temperatures in the range 80° C.-180° C. to solubilize lignin component to an extent of 90%-95% as well as solubilizing residual hemicellulose to obtain an undissolved fibrous organic biomass and a soluble fraction containing lignin, followed by precipitation of lignin out of the soluble fraction with mineral acid, d) separating and washing the undissolved fibrous organic biomass and bleaching the undissolved fibrous organic biomass with 1-10% by weight of sodium chlorite or chlorine dioxide, at a temperature of 20° C.-90° C., for a period of 1-18 hrs, at a pH of 3.5-4.0 to form a bleached fibrous organic residue, e) separating, washing and drying the bleached fibrous organic residue to obtain a pulp containing 90%-94% α-cellulose.