Fractionation of wood polymers by carboxymethylation: Exploring the strategy

Abstract

We explored the feasibility of fractionating wood polymers in situ by carboxymethylation to yield the carboxymethyl derivatives of cellulose (CMC), hemicelluloses, and lignin for potential industrial applications. The initial water-soluble materials formed were a mixture of hemicelluloses and cellulose derivatives, and also contained some lignin (3%–5%). Interestingly, the water-insoluble residue after another carboxymethylation treatment gave essentially a CMC product containing less than 1% of residual lignin. Thus, the bulk of wood lignin is less reactive than the polysaccharide components under typical carboxymethylation conditions. Also, a hot water pre-extraction or dilute acid pre-treatment of wood samples was found to significantly enhance the reactivity of the cellulose component. A preextraction approach would facilitate CMC preparation and also provide the flexibility to convert the extracted hemicelluloses to other bio-based fuels or materials.