Lignin–carbohydrate complexes from sugarcane bagasse: Preparation, purification, and characterization

• Published in: Carbohydrate polymers Vol. 62; no. 1; pp. 57 - 66
• Main Authors: Singh, R., Singh, S., Trimukhe, K.D., Pandare, K.V., Bastawade, K.B., Gokhale, D.V., Varma, A.J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 17.10.2005; Elsevier Science
• Subjects: Applied sciences; Biodegradability; Exact sciences and technology; Hardwood lignins; lignin; Lignin and derivatives; Lignin–carbohydrate complex; Natural polymers; Physicochemistry of polymers; Softwood lignins; Sugarcane bagasse; Sulfur-free lignins; Xylanase enzyme; xylanases; Biodegradability; Xylanase enzyme; Lignin–carbohydrate complex; Sulfur-free lignins; Hardwood lignins; Sugarcane bagasse; Softwood lignins; Lignin; Purification; Molecular structure; Lignocellulosics; Experimental study; Thermal stability; Sugar cane(by product); Bagasse; Enzymatic digestion; Physical separation; Lignin-carbohydrate complex; Agricultural waste; Lignosulfonate; Lignin derivatives
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2005.07.011

Lignin–carbohydrate complexes were isolated from sugarcane bagasse by a process, which yielded sulfur-free lignins. These could be made carbohydrate-free, if necessary, by treatment with xylanase enzyme. A study of the preparation, purification, and characterization of such lignin–carbohydrate complexes, comparison with commercial lignin samples (wood based as well as bagasse based) and some other lignin derivatives was made by using a variety of analytical tools such as FTIR, HPLC at three different UV-wavelengths, GPC, thermal analysis and elemental analysis. The use of such a diverse range of lignin–carbohydrate complex samples enabled us to predict the sensitivity of the various analytical techniques for characterization of complex polymers containing carbohydrate moieties. Evidence for lignin–carbohydrate complex was detectable by FTIR as well as HPLC studies. Thermal analysis studies showed the crucial effect of carbohydrate groups, the content of aliphatic chains, and the sulfur content of the lignins. Generalized structures of lignin–carbohydrate complexes obtained from various sources using different preparation methods and chemical modifications are presented. This will aid the applications development effort with advantageously using lignins containing low levels of carbohydrate moieties as reactive sites as well as biodegradability inducing sites.