| The development and utilization of biomass resources is considered to be an effective way to solve the increasingly depleted fossil resources and environmental resources.China is a large agricultural country with abundant bamboo resources.Bamboo leaves is a traditional Chinese herbal medicine,which contains a variety of active ingredients,a large number of cellulose,hemicellulose and lignin.When the active substances were been extracted of bamboo leaves,the remainders often been discarded or burned,resulting in great waste and environmental problems.In addition,due to the complexity of the structure of hemicellulose and the complex interactions between the components,it is hard to be efficient utilization hemicellulose.In order to realize the high efficient utilization of bamboo resources,the following studies were carried out on the leaves of Phyllostachys Pubescens in this study.1.After the lipids were removed by methanol-chloroform(1: 1,v/v),the polyphenols were extracted by ultrasonic-assisted organic solution.The effects of solid-liquid ratio,ultrasonic extraction time,extraction temperature and the concentration of ethanol on the extraction rate of polyphenols in bamboo leaves.The optimum extraction process was optimized by orthogonal experiment.The extraction temperature was 70 ?,ultrasonic time was 60 min,material ratio was 1:20 and ethanol concentration was 70%.The extraction rate of bamboo leaves polyphenols was 1.031%.2.The antioxidant activity of polyphenols was studied by investigating the removal of DPPH free radicals and ABTS free radicals.The results showed that bamboo polyphenols have a strong ability to scavenge free radicals and have good antioxidant activity.3.The hemicellulose was extracted from the leaves of bamboo leaves by triethylamine-sulfur dioxide,0.5,1.0,2.0,3.0 mol/L KOH and so on.Five hemicellulose samples were obtained and total weight 2.019 g,accounting for 20.19% of raw materials.The chemical structure,surface structure and thermal stability of the hemicellulose components were determined by Fourier transform infrared spectroscopy(FT-IR),gas chromatography(GC),thermogravimetric analysis(TG)and scanning electronic microscopy(SEM)Sexual characterization.GC map showed that the monosaccharides in the extracted components were mainly xylose and arabinose.The FT-IR spectra showed that the structure of the arabinose-xylan and the uronic acid structure were present in the extracted components.TG spectra showed that there were two weight loss processes in the neutral solution and the low concentration of lye.The hemicellulose extracted from the high concentration of alkali had four weight loss processes,and the thermal stability was different.The SEM showed that the hemicellulose surface structure increased with the increase of the surface voids.4.Using the sulfur trioxide pyridine complex-DMF method,LiCl as catalyst and N,N-dimethylformamide(DMF)as a sulfuric acid ester solvent,the extraction of hemicellulose samples were swere subjected to sulfuric acid modification in the homogeneous reaction system.The effects of material ratio,reaction time and reaction temperature on the degree of substitution of hemicellulose sulfate were investigated.The experimental results showed that the material ratio was the main factor of sulfation reaction.The hemicellulose sulfates were prepared at the material ratio of 1: 3,the reaction temperature of 50 ? and the reaction time of 3 h.The modified sulfuric acid esterification was characterized by elemental analysis,FT-IR,UV spectroscopy(UV),TG The physicochemical properties,FT-IR and UV spectra of hemicellulose showed that the extracted hemi-fibers were attached to the sulfuric acid group and the hemicellulose sulfate was 1.68 by means of elemental analysis.The TG spectra showed that hemicellulose Sulfate has four weight loss processes,and the thermal stability deteriorates compared to hemicellulose. |
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