Research On Dissolution And Separation Of Bamboo In Ionic Liquid Mixture Solvent

Bamboo is a major biomass resource with the largest planting acreage in China, and alsohas great application potential. However, bamboo has little applications as chemical rawmaterials. This is because the density and strength of bamboo is higher than wood and straw.What’s more, the distribution of cellulose, hemicellulose and lignin in bamboo has obviousinhomogeneity. So bamboo is much more difficult to deal with than wood and straw, whichgreatly reduces its utilization efficiency. So in this paper, green solvent ionic liquid waschosen to selectively dissolution and separation bamboo, providing a theoretical basis for theapplication of bamboo as raw chemical materials.In this paper, one-pot method of synthesizing [BMIM]Br was proposed by simplifyingthe traditional method. Then the one-pot synthesized [BMIM]Br was mixed with ethanol andwater in a certain ratio and used to selectively dissolve bamboo lignin, at the same timecellulose could be reserved to a greater degree. Meanwhile, ionic liquid [AMIM]Cl, whichhad good effect of dissolving lignocellulose reported by literature, was used to dissolve andseparate bamboo.On the basis of single factor study of the experiment conditions, orthogonalexperiments were used to optimize the conditions of the dissolution and separation process.The results were as follows: in the one-pot synthesized [BMIM]Br mixture solvent, reactiontemperature190℃, reaction time5h,[BMIM] Br/ethanol(v/v)=3:7, water content2%.Under the condition, bamboo dissolution yield can reach54%, lignin purity can reach91%,and yield can up to67%, while cellulose purity can reach85%, and yield can up to94%. Inthe [AMIM]Cl mixture solvent, reaction temperature190℃, reaction time5h,[BMIM] Br/ethanol(v/v)=3:7, water content4%. Under the condition, bamboo dissolution yield can reach64%, lignin purity can reach94%, and yield can up to66%, while cellulose purity can reach91%, and yield can up to80%. Compared to the results of the two kinds of ionic liquidsmixed solvent, cellulose could be reserved to a greater degree on the dissolution andseparation process of the one-pot synthesized [BMIM]Br under the optimum conditions, sothe yield of cellulose is higher. At the same time, GPC、1H-NMR、FTIR、TG-DTG、HPLCand some other determined methods were used to examine the products. It was found that the chemical structure of products did not change significantly during the separation process; asmall amount of lignin hydrolyzed, hemicellulose degraded to sugar and remained in themixture solvent.In order to recycle the ionic liquids, two steps of sugar conversion process were used toseparate the sugars. Under the best conditions the sugar separation yield can up to81%, andthe yield of product furfural can reach50%. Repeated experiments were conducted to test therecovered ionic liquids and the results showed that the recovered ionic liquid can retain theoriginal characteristics and activity, and the dissolution efficiency can still very high.In conclusion, bamboo components were successfully dissolved and separated by theionic liquid mixture solvent. And the separation efficiency is better than the traditionalseparation methods. Meanwhile ionic liquid was successfully recovered and achieved goodreuse efficiency. Therefore, the ionic liquid mixture solvent has some potential applications inthe direction of dissolution and separation of bamboo.