芍药苷及芍药内酯苷在超临界CO_2中无限稀释扩散系数的测定与计算

Measurements and Prediction of Infinite Diffusion Coefficients of Paeoniflorin and Albiflorin in Supercritical Carbon Dioxide

在温度308.15~328.15 K,压力10~18 MPa,运用Taylor峰扩展法测定了芍药苷及芍药内酯苷在超临界CO_2中无限稀释扩散系数,两组分的扩散系数均随温度升高而增大,随压力升高而减小,随改性剂乙醇含量的增加而减小,并建立了芍药苷与芍药内酯苷的扩散系数与超临界CO_2的密度关联方程。分别采用修正的Wilke-Chang、Lusis-Ratcliff、Hayduck-Minhas模型和Dymond-Hildbrand-Batschinski(DHB)模型预测了芍药苷及芍药内酯苷在夹带乙醇的超临界CO_2中的三元扩散系数,与实验测定值对比表明,DHB模型的预测效果最好,对芍药苷及芍药内酯苷的平均绝对偏差分别为3.11%和4.96%。

Diffusion coefficients of paeoniflorin and albiflorin in SC(supercritical)-CO_2 were measured using Taylor peak extension under 308.15~328.15 K and 10~18 MPa. Effects of temperature, pressure and modifier content on diffusion coefficients were investigated. The diffusion coefficients of the two solutes increase with the increase of temperature and decrease with the increase of pressure or modifier content. Associated equations between the diffusion coefficients and the density of paeoniflorin and albiflorin were established, and the best fitting equation was selected. The diffusion coefficients of paeoniflorin and albiflorin in SC-CO_2/CH_3CH_2OH were predicted by the modified Wilke-Chang model, modified Hayduck-Minhas model, modified Lusis-Ratcliff model and Dymond-Hildbrand-Batschinski(DHB) model. Compared with the experimental results, the DHB model shows the best prediction and the average absolute deviations of paeoniflorin and albiflorin are 3.11 % and 4.96 %, respectively.