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在温度305.15~323.15 K、压力10~18 MPa范围内,采用Taylor峰扩展法测定了Z-藁本内酯在超临界CO2中的无限稀释扩散系数。结果表明,扩散系数范围在(2.75~5.55)×10-8m2/s之间,并随温度升高而增大,随压力和超临界CO2密度增大而减小,当温度和压力一定时,改性剂乙醇含量的增加能促进扩散系数缓慢增大。分别采用修正的Wilke-Chang、Scheibel、Lusis-Ratcliff、Reddy-Doraiswamy、He-Yu-Su模型预测了Z-藁本内酯的扩散系数,与实验测定值对比表明,平均绝对偏差分别为9.352%、9.356%、9.354%、9.360%和10.444%,均能很好的预测Z-藁本内酯在超临界CO2中的无限稀释扩散系数。
The infinite dilution diffusion coefficient of Z-ligustilide in supercritical CO2 was determined by Taylor peak expansion method at temperature of 305.15 ~ 323.15 K and pressure of 10 ~ 18 MPa. The results show that the diffusion coefficients range from (2.75 to 5.55) × 10-8m2 / s, and increase with increasing temperature. With the increase of pressure and supercritical CO2 density, when the temperature and pressure are constant, The increase of ethanol content in modifier can promote the slow increase of diffusion coefficient. The diffusion coefficient of Z-ligustilide was predicted by the modified Wilke-Chang, Scheibel, Lusis-Ratcliff, Reddy-Doraiswamy and He-Yu-Su models respectively. The experimental results showed that the average absolute deviations were 9.352% , 9.356%, 9.354%, 9.360% and 10.444%, all of which can well predict the infinite dilution diffusion coefficient of Z-ligustilide in supercritical CO2.