Title
Comparison of isolated hemicelluloses from soda cooking black liquor with commercial and bacterial xylan
Authors
HAO REN and SHIGETOSHI OMORI

Received August 1, 2013
Published Volume 48 Issue 7-8 July-August
Keywords hemicellulose, carboxymethylation, bacterial xylan, 4-O-methyl-D-glucurono-D-xylan, comparison

Abstract
In this study, hemicelluloses were isolated from soda cooking black liquor. The structural features of different raw materials (wheat straw, rice straw, reed) were characterized and compared with those of commercial 4-O-methyl-D glucurono-D-xylan and bacterial xylan, using Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetry (TG) and Scanning Electron Microscopy (SEM). Furthermore, hemicelluloses isolated from black liquor and two kinds of xylan were converted to carboxymethyl hemicelluloses (CMH), using carboxymethylation with sodium monochloroacetate and sodium hydroxide in 2-propanol medium. The reactions were performed at 55 ºC for 4 hours, with 33 mL 2-propanol and 1 mL 30% NaOH per 0.6 g hemicelluloses. The product had maximum degrees of substitution (DS) of 0.54 for wheat straw, 0.55 for rice straw, 0.67 for reed, 0.65 for commercial xylan and 0.43 for bacterial xylan (which can be completely soluble in water). The structures of the resulting polymers were characterized using FT-IR, TG, SEM and Gel Permeation Chromatography (GPC). The objectives of this study were to investigate the extractability of hemicellulosic components from cooking black liquors, to synthetize CMH and evaluate their performance.