Response Surface Optimization of Alkali Extraction and Characterization of Poplar Hemicellulose

Hemicellulose was isolated from poplar powder using alkaline hydrolysis coupled with alcohol precipitation. Response surface methodology was applied to study the effects of sodium hydroxide concentration, reaction time, and temperature on the extraction yield. The optimal conditions for the extraction of the hemicellulose from poplar powder were an alkaline mass fraction of 9.5%, reaction time of 4 h and 12 min, and temperature of 78 degrees C. The extraction yield reached 52.8% under this optimal condition. Fourier-transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis, and sugar component analyses showed that the obtained hemicellulose with excellent water absorption and heat resistance consisted mainly of 4-O-methyl-glucurono-xylan, and the molar ratio of xylose to glucuronic acid on the molecule chains was 3.95.