Study On The Selection And Application Of 1,8-cineole Separation Aid

Eucalyptus oil is a kind of aromatic oil and its main component is 1,8-cineole.1,8-cineole is used in food,daily chemicals,medicament and so on,because of its good anti-bacterial,anti-inflammatory,antiseptic and insecticide repellent effect.Eucalyptus oil has complex components and the majority of impurities are isomers or have the similar molecular structure with 1,8-cineole.So they have similar physical and chemical properties,which bring great difficulties to separate and purify 1,8-cineole.In this work,"adjustable" ionic liquids were used as additives to improve the selectivity for eucalyptus oil separation.Batch vacuum distillation and supercritical fluid extraction processes were investigated in purification of 1,8-cineole from coarse oil.The main contents of this thesis were organized as the following:1)The COSMOtherm software was used to screen ionic liquids for separation.The specific surface screening charge density distribution and chemical potential were calculated by quantum chemical method for the main components of eucalyptus oil and ionic liquids.The solvent capacity and selectivity of ionic liquids in eucalyptus oil were predicted by COSMO-RS.According to the principle of maximum solvent capacity and selectivity,the most suitable ionic liquids were selected.The results showed that 1-octyl-3-methyl imidazolium bis((trifluoromethyl)-sulfonyl)-imide([OMIM]+[NTf2]-),1-decyl-3-methylimidazolium bis((trifluoromethyl)-sulfonyl)imide([DMIM]+[NTf2]-)and dibutyl ammonium bis((trifluoromethyl)sulfonyl)-imide([N4,4,H2]+[NTf2]-)had good solvent capacity and selectivity in eucalyptus oil system.Then they were selected as cosolvents for batch vacuum distillation.2)Data of saturated vapor pressure and vapor-liquid phase equilibrium were measured.The saturated vapor pressure of α-pinene,1,8-cineole and p-cymene were measured,and their Antoine formula were associated.The vapor-liquid equilibrium data between 1,8-cineole and α-pinene,limonene,p-cymene,y-terpinene and α-terpineol were measured,respectively.At the same time,the effect for the phase equilibrium data of ionic liquids-[OMIM]+[NTf2]-,[N4,4,H2]+[NTf2]-and[DMIM]+[NTf2]-were also measured.3)Batch vacuum distillation was applied in separation of 1,8-cineole.Pressure,reflux ratio and cosolvent in purifying 1,8-cineole were investigated.The experimental results indicated that the appropriate pressure was 5.0kPa and the reflux ratio was R2,and the sequence of the cosolvent interact with 1,8-cineole from strong to weak was:[OMIM]+[NTf2]->[N4,4,H2]+[NTf2]>ethanol>[DMIM]+[NTf2]>no cosolvent,and the optimum amount for[OMIM]+[NTf2]-is 1wt%.4)Extraction behavior of eucalyptus oil with supercritical CO2 was studied.Extraction pressure,temperature,time and entrainer dependences were researched.The experimental results indicated that ethanol as a cosolvent could improve the extraction rate and extraction percentage composition.For 1,8-cineole,the appropriate pressure was 15000kPa and the temperature was 45℃.However,it was benefit to the extraction of limonene,p-cymene and y-terpinene,except 1,8-cineole,under CO2 flow rate of 18 g/min.Extraction time could not improve the concentration of the substance obviously,but increase the yield of these components.