Extraction And Degradation Of Hemicellulose For The Production Of Xylose From The Bamboo

Bamboo bits was as the raw material in this study,it was first extracted by distilled water with 60% ethanol precipitated,got the water-soluble impure hemicellulose.From the High Performance Liquid Chromatography(HPLC),Fourier Transform Infrared Spectroscopy(FT-IR),and Nuclear Magnetic Resonance Hydrogen Spectrum(1H NMR)analysis found that it was glucose-based,contained a certain of xylose and a small amount of arabinose,which was a kind of mixed polysaccharide with glucan,xylanase and so on.It was further purified on DEAE-Cellulose-52 chromatography,eluted by distilled water,0.1 M NaCl,0.3 M NaCl,0.5 M NaCl,0.1 M NaOH,0.3 M NaOH and 0.5 M NaOH,and isolated 5 hemicellulose components,then the polysaccharide that distilled water eluted given another purification by Sephadex G-100 column chromatography,got two complete separation of hemicellulose.The fifteen hemicellulose fractions were further sequentially extracted by 1%,3%,5%,10% and 15% NaOH aqueous solution after water extracted of the bamboo,using HPLC,FT-IR,and 1H NMR techniques to study hemicellulose obtained.The results showed that,the sugars of the hemicellulose mainly consisting of xylose with glucose and a small amount of arabinose.The alkali soluble hemicellulose of bamboo is xylanase mainly composed of β-xylose as the main chain and arabinose as the branched chain,contained a small amount of 4-O-methyl-D-glucuronic acid.The bamboo bits was further used to study the optimal condition of hemicellulose produce.Firstly,ammonia exploded was used for bamboo pretreatment.It indicated that the ammonia exploded method is effective and can be used as a pretreatment method for hemicellulose utilization with the hemicellulose retained 82.62%,but the hemicellulose extracted the explosion of ammonia material have was only 2.43% more than the raw materials have under the same concentration of alkali.It is rational to use the bamboo without pretreatment as the raw material from an economic point of view and equipment safety considerations.After the selection of hemicellulose material,on the basis of the single factor,the optimum condition for the extraction of hemicellulose is obtained by means of the orthogonal experiment.The best extraction of hemicellulose was achieved with 8% NaOH,4 hours reaction time under 55 ℃with solid-liquid ratio 1:10.The yield of hemicellulose mostly depends on alkali concentration,followed by time and temperature,and the effect of solid-liquid ratio was the least.The orthogonal test was also carried out on the hemicellulose conversion into xylan by sulphuric acid.The result showed that the best reaction conditions was that 0.25 M H2SO4 with 90-min reaction time under 130 ℃with solid to Liquid ratio 2:100(g/mL).Sulfuric acid concentration is the main factor affecting the solution of hemicellulose,followed by time and temperature,and the effect of solid-liquid ratio was the least.The acid solution was further processed to higher purity xylose,the yield was 79.60%.