ARS | Publication request: Chemical modification of cotton-based natural materials: products from carboxymethylation

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 19, 2010
Publication Date: February 16, 2011
Citation: Cheng, H.N., Biswas, A. 2011. Chemical modification of cotton-based natural materials: products from carboxymethylation. Carbohydrate Polymers. 84:1004-1010.

Interpretive Summary: One of our research goals is to find new utilization for agricultural byproducts and waste. Two of the undervalued products in the cotton process are cotton burr and cottonseed hull. In this work, we have developed a process that permits us to convert 26 – 58% of burr and hull into water-soluble mixtures of carboxymethyl cellulose (CMC) and carboxymethyl xylan (CMX) without prior separation of cellulose from non-cellulosic components. In addition, some lightly carboxymethylated insoluble materials are obtained in the reactions. All these materials are anionic polymers and perhaps may be considered for use in low-cost applications.

Technical Abstract: The processing of cotton generates a number of byproducts, two of which are cotton burr and cottonseed hull. A proximate analysis indicates that they contain about 30-31% cellulose, 17-18% lignin and lesser amounts of protein and oil. They differ in level of hemicelluose with burr containing ~6% and hull containing ~20%. Both materials can swell in aqueous NaOH-isopropanol solutions at pH 13.6 in which state they become susceptible to reaction with monochloroacetic acid. The products of this reaction consist of a water-soluble fraction (weight yields ranging from 28-58%) and a water-insoluble residue. The water-soluble fractions produce clear films that dissolve slowly in water with viscosities that are somewhat lower than for carboxymethyl products generated from purified cellulose. The products were characterized by NMR and IR and were found to consist mostly of carboxymethyl derivatives of cellulose and hemicellulose.