Hemicellulosic polymer from Vetiver grass and its physicochemical properties

Abstract

Chemical composition of two ecotypes of the Vetiver grass (Vetiveria zizanioides nash) leaves has been investigated using the gravimetric method. The principal polysaccharides found in samples were hemicelluloses (ca. 38%), followed by cellulose (ca. 27%). Protein content determined by bicinchoninic acid assay using bovine serum albumin (BSA) as a standard was approximately 5%. Lignin content determined by acid chlorite method was approximately 10%. Ash content was 3% consisting of mainly silica (ca. 50%). The obtained hemicelluloses with the molecular weight of 30,000 showed the decomposition temperature at 310 °C. In order to determine an optimum condition for extraction of hemicelluloses, effects of process parameters: alkaline type (NaOH, KOH, Ca(OH)2and Ba(OH)2), alkaline concentration (0.025-4 M), extraction time (2-18 h) and temperature (25-60 °C) were studied. It was found that all parameters influenced on the hemicellulose yield and properties in various degrees. Finally, an optimum condition giving a maximum yield of 35% hemicelluloses was recommended as 4 M NaOH at ambient temperature for 8 h. © 2003 Elsevier Ltd. All rights reserved.