| CO2 responsive switch solvent is an intelligent and controllable green solvent,whose properties will change reversibly after introducing and removing CO2.Taking advantage of this feature,it is possible to achieve separation and purification of some chemicals.Compared with traditional separation techniques such as salting-out and rectification,CO2 responsive switch solvents have several merits like simple operation,environmental protection and cyclicutilization.Therefore,the author chooses 1-ethylpiperidine(EP)and N,N-dimethylbutylamine(DMBA)to construct two kinds of CO2 responsive switch solvents,1-ethylpiperidine bicarbonate([EPH][HCO3])and N,N-dimethylbutylamine bicarbonate([DMBAH][HCO3]).Some physical properties of tertiary amine salt([EPH][HCO3])solution at different temperatures and concentrations are measured,and the ternary phase equilibrium data of tertiary amine salt([EPH][HCO3]and[DMBAH][HCO3])+organic matter(1,3-dioxolane,1,4-dioxane,tetrahydrofuran and L-threonine)+water system is measured,which provides basic data and theoretical basis for its application in industry?The main research contents are as follows:1 The density,viscosity,refractive index and electrical conductivity of[EPH][HCO3]were measured at the temperature from 283.15 K to 308.15 K and the changes of physical properties with temperature and concentration were analyzed.Based on the measured density and viscosity data,the volume properties of the solution under the system(apparent molar volume,expansion rate of standard partial molar volume and standard partial molar volume)and viscosity properties are calculated and discussed.A molecular thermodynamic model suitable for the system was established,and the model parameters and calculated values were determined.The experimental data are correlated by the model,The values of average relative deviations(RAD)of the system were 4.67×10-3,3.13×10-3,1.06×10-4 and 7.68×10-3,respectively.The calculated results were in good agreement with the experimental results.2 The liquid-liquid equilibrium data of the ternary system of tertiary amine salt([EPH][HCO3]and[DMBAH][HCO3])+heterocyclic organic compound(1,3-dioxolane,1,4-dioxane and tetrahydrofuran)+water were measured respectively at 283.15 K,293.15 K and 303.15 K,according to which the ternary phase diagram was drawn.The e-NRTL model is used to correlate the ternary data.The maximum RAD value of the system is exceed 6.62×10-2,and the root mean square deviation(RMSD)is less than 8.76×10-3.The model correlation result is good.The Othmer-Tobias equation,Bancroft equation and setschenow-type equation are used to verify the experimental results.The correlation coefficient R2 is close to 1,indicating that the experimental data are reliable.Comparing several systems,it is found that[EPH][HCO3]has the best extraction effect on 1,4-dioxane.3 The solubility of L-threonine in different concentrations of tertiary amine salts([EPH][HCO3]and[DMBAH][HCO3])was measured at the temperature from 278.15 K to 308.15 K.What was revealed was that the solubility of L-threonine decreased with the increase of salt concentration.The simplified Apelblat equation,Ah equation and e-NRTL equation were used to correlate the phase equilibrium solubility data,The RAD value and RMSD value were less than 4.11×102 and 3.70×104,respectively,and the correlation effect of the Apelblat equation was the best.Meanwhile,the standard dissolution enthalpy and thermodynamic transfer properties of L-threonine in the mixed system were also calculated.The ternary phase equilibrium data of the tertiary amine salt+L-threonine+water system were measured at 283.15 K,293.15 K and 303.15 K,and the phase diagram was drawn.It is found that[DMBAH][HCO3]has a slightly better salting-out effect on L-threonine. |
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