Study On Pulping Method Of Straw In Ionic Liquids

Ionic liquids was widely used as a green solvent in recent years. The synthesis of ionic liquids and pulp cooking condition of straw in the ionic liquids was studied.Firstly, some ionic liquids were synthesized. Bromide1-ethyl-3-methylimidazole ([Emim]Br) was synthesized in traditional and microwave radiation methods respectively. The synthesis conditions were optimized based on the single factor experiment and orthogonal experiment and Synthesis kinetics of [Emim]Br was studied preliminarily under microwave radiation conditions, the results showed that the reaction was a second order reaction, and the reaction rate constant k=0.0993. Synthesis and the optimum conditions of sulfonate triethylamine ([HN+-(C2H5)3]HSO4) ionic liquids was studied by traditional method. Also synthesized two alkaline ionic liquids---hydroxide1-ethyl-3-methylimidazole ([Emim]OH) and alcohol amine ionic liquids ([NH-(C2H4OH)3]+) with references, the results showed good agreements with the reference data.Secondly, pulp cooking condition of straw in different ionic liquids was investigatated.In this paper, sulfonate triethylamine ([HN+-(C2H5)3]HSO4-) ionic liquids and alcohol amine alkaline ionic liquids ([NH-(C2H4OH)3]+) were the main objects for deeper researches, it is found for sulfonate triethylamine ([HN+-(C2H5)3]HSO4-) ionic liquids that the satisfied pulping and delignification result can be achieved with the conditions(8:1of liquid-solid ratio,90%of concentration of ionic liquids,60min of cooking time) under traditional heating condiations. When ratio of liquid to solid was8:1, concentration of ionic liquids was90%, microwave power was150W, and cooking time was20min, which showed a good pulping and delignification results under microwave irradiation conditions, and the yield of pulp was around50%. The optimum extraction conditions for pulping of straw in alcohol amine alkaline ionic liquids ([NH-(C2H4OH)3]+) defined by orthogonal test are:ratio of liquid to solid was5:1, microwave power was350W, cooking time was30min, and under the optimum conditions, the yield of pulp was around40%.Meanwhile, some preliminary exploration on pulping for alkaline ionic liquids ([Emim]OH) and neutral ionic liquids ([Emim]Br) were carried out, The best process conditions for alkaline ionic liquids ([Emim]OH) by traditional heating were obtained through tests. including70%of concentration of ionic liquids,12:1of liquid-solid ratio,90℃of cooking temperature,90min of heating time, and the yield of pulp was60%. Investigation on neutral ionic liquids ([Emim]Br) shows that satisfied pulping result can be achieved when microwave power was100W. reaction time was8min,reaction temperature was controlled at100℃Finally, some ionic liquids were recovered and reused, FT-IR spectra of original and recovered ionic liquids showed that the structure was not change, the recovered ionic liquids could be reused for several times with stable performance, and it had almost no effect on straw pulp.