Study On Dissolving Hemicellulose Polysaccharide From Bamboo And The Whole Bamboo In Ionic Liquids

Bamboo is an important lignocellulosic biomass resource,which is widely distributed in China.However,because of the complex covalent bond and hydrogen bond network among the three main components including cellulose,hemicelluloses,and lignin in bamboo cell wall,the bamboo cell wall shows strong resistance to degradation,resulting in the great restriction of efficient utilization of bamboo resources.Ionic liquids(ILs)perform many excellent characteristics,such as designability,low volatility,recyclability,and so on.Earlier study showed that ILs have great potential in the effective dissolution of the main components of plant cell wall.Therefore,exploring the dissolution of the main components of bamboo in ILs and the interaction between the components and ILs,as well as optimizing the conditions of ILs pretreatment for bamboo to improve the efficiency of enzymolysis of bamboo are great significance for the efficient pretreatment of bamboo biomass.In the present study,the dissolution law and dissolution mechanism of bamboo hemicellulose in imidazolium ILs were discussed,and a series of works were carried out on the chemical composition,structure and yield of reducing sugar of bamboo after ILs pretreatment.The main conclusions were given as following:1.The solubilities of hemicellulose in the six ILs of BmimAc,EmimAc,AmimAc,PrmimAc,HOemimAc,and HmimAc were determined,and the possible reason for the difference of the solubility of hemicelluloses in the ILs was analyzed.The results showed that the difference of the structure of the side chain at N1 position on the 3-methylimidazolium ring of the ILs resulted in the difference of β value which affected the solubility of hemicellulose in the ILs.The acidic proton at the C2 position(C2-H)on the imidazolium ring of ILs was more likely to form hydrogen bonds with hydroxyl oxygen atoms in hemicellulose.Basic Ac-possibly interacted with hydroxyl protons in hemicellulose to form hydrogen bonds.Anions and cations in ILs played a synergistic role in the process of dissolving hemicellulose.The concentration of hemicellulose in the ILs also had greater impact on the interaction between the hemicellulose and ILs.2.Hemicellulose was regenerated from three IL solutions of EmimAc,BmimAc and AmimAc,and the recovered hemicellulose samples were characterized.The results showed that the dissolution temperature had great effect on the recovery yield of hemicellulose.The chemical structure of regenerated hemicellulose was similar to that of the original hemicellulose,and the influence of ILs pretreatment on the structure of hemicellulose was almost negligible.3.The solubility of bamboo powder in two different ILs(BmimAc and BmimCl)was measured under microwave-assisted heating,and the chemical composition,structure and yield of reducing sugar of bamboo were analyzed.The results showed that under the same heating conditions,the dissolving ability of BmimCl for bamboo powder was stronger than that of BmimAc,but the regeneration rate of bamboo powder after BmimAc pretreatment reached 73.03%,which was much higher than that after BmimCl pretreatment.The pretreatment of bamboo powder by the ILs was beneficial for enzymatic hydrolysis to produce sugar.The yield of glucose after enzymatic hydrolysis of bamboo powder could reach 96.2%,and the yield of xylose was 73.59%.The recovered IL obtained by the simple recycling process had poorer effect on the treatment of bamboo biomass,and the number of recycle times of ILs also affected the pretreatment efficiency.4.A factory design with an annual output of 900 tons of glucose was carried out.The design content included product standards,product solutions,site selection,process flow,and material balance.The CAD design drawings of the factory included factory floor plan,the floor plan of the workshop,and the perspective view of the piping layout of the workshop.