(471e) Characteization of Solubilized Biompolymers Fractionated From Alkali Pulping Liquors

Alkaline extraction of lignin and hemicellulose from woody biomass can be integrated with existing chemical pulp mills and can potentially increase revenue by utilizing the non-cellulosic portion of the biomass for fuels and chemicals rather than for combustion for heat and power.  The overall purpose of this work is to characterize the extractability, recoverability, and properties of the solubilized hemicellulose (glucuronoxylan) and lignin during the alkali impregnation and heat-up stages of soda pulping for two hardwood species, Acer saccharum (sugar maple) and Betula pendula (silver birch). Liquors will be sampled throughout the heat-up and during the course of pulping.  A material balance will compare the difference between the extracted material in the pulping liquor and the residual wood chips after pre-extraction based on total mass, xylan, and lignin removed.  The recoverable yield of the solubilized biopolymers will be determined using a variety of methods including aggregation and precipitation by acidification followed by ultrafiltration or by complete polymer precipitation by ethanol to determine an upper recoverability limit.  The properties of the recovered biopolymers as a function of extraction condition will be characterized by a variety of techniques including total composition, total polymer molecular weight distributions by size exclusion chromatography and xylan number average degree of polymerization by a novel reducing end assay.  Lignins will be fractionated using sequential solvent extraction and the properties of these lignins will be characterized by SEC and ¹³C NMR.