Coupling between acid precipitation and resin adsorption for purifying alkaline extracted hemicellulose from sugarcane bagasse

Abstract

Hemicellulose is considered the second most renewable component in lignocellulosic biomass after cellulose, and can be used in value-added industrial applications including medical dressing, packaging materials and hydrogels. Hence, the purification methods of different acid precipitation conditions, ethanol precipitation and resin adsorption were investigated. In this paper, the results showed that most of the lignin was removed by acid precipitation. With the adjustment of pH value from 6 to 2 by acid precipitation, the less lignin remains in hemicellulose samples, the higher the purity of hemicellulose. After resin adsorption treatment, the molecular weight of hemicellulose increased slightly and the weight average molecular weight of Ha2 (Ha2 is hemicelluloses precipitated at pH = 2) is 7.91 × 104 g/mol among, the branching degree of hemicellulose decreased slightly, the thermal stability of hemicellulose increased slightly. It can be shown from 2D HSQC NMR that the structure of hemicellulose did not change significantly before or after adsorption and at different pH values. Trace lignin-carbohydrate complexes (LCCs) structures were remained in hemicellulose sample. The slight loss of hemicellulose caused by resin adsorption is due to LCCs. The sensitivity of XAD-16N resin to phenyl glycoside bond (PhGlc) of different forms was different.