| Biomass resources have become important sources of new energy, new material and new chemical in the current global energy crisis. Bamboo is a major biomass raw material resource with the largest planting acreage in China. Bamboo is also particularly important in many industries, including food, chemical, pharmaceutical, health care, pulp and paper, construction, and new energy. As a biomass component, hemicellulose research also becomes more and more important due to its significant amount and the broad application prospects. Ionic liquid (IL) has started to play an important role in the green chemical development in recent years. Its low vapor pressure, high stability, non-flammable, modifiable for specific purpose, and ease of recovery features have made it very attractive in the fields of electrochemistry, organic synthesis and catalytic chemistry. However, the application of ILs in the separation of biomass components is still in its infancy stage. The hemicelluloses in the bamboo shoots and one month old young bamboo were extracted using the ionic liquids and alkaline, and the structure of the hemicelluloses was characterized.The processes of hemicelluloses extraction using [Amim] Cl and [Emim][OAC] were developed, and used to separate the hemicellulose from biomass. The process was proved to be simple and had much less environmental impact than traditional extraction methods. At the same time, the traditional2%NaOH alkaline extraction method was also used as a comparison with the ILs extraction method.The galacturonic acid content and the neutral sugar composition in the hemicellulose were determined and analysized respectively. The results indicated that the uronic acid content in the hemicellulose ranges between0.2%and7.6%for hemicellulose obtained with different extraction methods, while neutral sugar compositions were similar for hemicellulose extracted with different methods, with xylose (6.1%-86%), arabinose (5.3%-20.9%), glucose (8.1%-55.2%) and a small amount of nect sugar. Hemicellulose characteristics were analyzed by FT-IR,1H NMR and13C NMR spectra methods. The result showed that the structural characteristics of hemicellulose extracted with different methods were very similar, all have the xylose main chain linked by1â†'4Glycosidic bond, with O-3or O-2substituted by acetyl, and α-L-furan arabinose and4-O-methyl-D β-D-xylopyranosyl-glucuronic acid as side chains. From SEM observations, the hemicellulose could present as sponge or solid piece structure, and that had nothing to do with the extraction method. Thermal decomposition characteristics of hemicelluloses extracted with different methods were analyzed by the thermal gravimetric analysis (TGA) method. The result showed that there was a large weight loss range which could be divided into four temperature ranges, the main pyrolysis stage occurred in the range of240℃-400℃. According to the TG-DTG curves, the maximum weight loss of the hemicellulose component occurred mainly in the range of250℃-300℃. The characteristics of the TG-DTG curves obtained for the hemicellulose derived from three extraction methods were very similar. The Coat-Redfern integral method was used to conduct the dynamic analysis for the maximum weight loss range of the hemicelluloses components. The activation energy E and pre-exponential factor A of each component were obtained and compared. |
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