(490s) Alkaline Hemicellulose Extraction and Solubility-Based Separation From Hardwoods

Authors: 
Hodge, D., Michigan State University


Woody cellulosic biomass presents a unique opportunity for the production of liquid biofuels and other chemicals from renewable resources. By utilizing woody biomass existing supply chains and infrastructure developed for the forest products industry can be employed which both shortens the timeline for commercialization for these technologies and greatly enhances the economic attractiveness of pretreatment technologies that can successfully work on these feedstocks. Therefore, the challenge is to integrate existing alkaline pulping processes with extraction processes that utilize the hemicellulose and lignin fractions for fermentation-based fuels, solid fuels, and chemicals. Overall, the goal of this work is to better characterize the impacts of these extraction processes on the properties of the solubilized biopolymers and the potential for solubility-based separations to recover useful hemicellulose and lignin fractions. An alkaline (e.g. soda pulping) pre-extraction before pulping or black liquor removal during pulping can permit use of the hemicellulose and lignin fractions for higher value fuels and chemicals. These solubilized hemicellulose and lignin fractions exhibit different functionalities due to their chemical alteration from the original biopolymer. Recovery of the soluble biopolymers from the pretreatment liquors can be accomplished through solubility-based separations such as adjustment of the pH or through the addition of an organic solvent to precipitate and recover the hemicellulose and/or lignin components from the liquid phase. The solubility of the hemicelluloses and lignins depends on their chemical properties such as degree of polymerization and acetylation. This work will characterize both the alkaline extraction and precipitation requirements for 4-O methyl glucuronoxylan from sugar maple (Acer saccharum) as a function of polymer chain length. Separation techniques of this nature can be utilized to remove sugars from a potentially harsh environment that is detrimental to not only enzymes for hydrolysis, but also micro-organisms for fermentation.