Process for obtaining cellulose acetate from agricultural by-products

Agricultural residues such as corn fiber, rice hulls and wheat straw can be used as abundant low-cost feedstock for production of fuel ethanol. However, the cost of cellulase enzymes to saccharify cellulose to glucose is a major hindrance. As an alternative, a novel process to obtain industrially important cellulose acetate from these by-products after removing hemicellulosic sugars was developed. Rice-straw, wheat hull and corn fiber were treated with dilute acid at a moderate temperature to hydrolyze the hemicellulose to monomeric sugars that can be fermented to ethanol. The cellulose was then treated with acetic anhydride and catalytic amount of sulfuric acid to make cellulose acetate. The production of cellulose acetate was confirmed by NMR analysis. The pretreatment used to hydrolyze the hemicellulose was also useful for cellulose acetate production. Without the pretreatment cellulose acetate conversions from wheat straw, corn fiber, and rice hulls were 0.5, 1.8 and 13.5, respectively. After pretreatment the conversion rate increased to about 25 wt% for all three agricultural residues used.