FRACTIONATION OF HEMICELLULOSE FROM RICE STRAW BY ALKALINE EXTRACTION AND ETHANOL PRECIPITATION

Abstract

© 2016, Malaysian Society of Analytical Sciences. All rights reserved. Hemicelluloses were extracted from rice straw using alkaline extraction and ethanol precipitation. The effects of different extraction conditions; temperature (45-65 °C), pH (4.5-6.5), and concentrations of NaOH (0.25-1 M) on the hemicellulose yield were investigated. Two hemicelllulosic fractions namely Ha 1 and Ha 2 were obtained by precipitation of alkaline soluble hemicellulose in 0.2 volumes and 4 volumes ethanol, respectively. The Ha 1 and Ha 2 were further characterized to obtain total sugar, monosaccharides and Klason Lignin content. The highest hemicellulose yield for Ha 1 was 4.00% obtained at 55 °C and pH 5.5 with 0.25 M of NaOH, whereas the highest hemicellulose yield for Ha 2 was 19.88% obtained at 55 °C and pH 5.5 with 0.5 M of NaOH. This study revealed that hemicellulose yield is dependent on the pH, temperature and concentration of NaOH in the alkaline extraction.