[关键词]
[摘要]
目的 研究紫苏Perilla frutescens叶中咖啡酸存在状态与其纳滤传质过程的相关性。方法 以紫苏叶中的咖啡酸为研究对象,改变溶液酸碱度调节咖啡酸游离-解离比例,收集不同存在状态下相应初始浓度和操作压力产生的截留率及其膜通量,基于纳滤分离中的溶解-扩散效应和电荷效应理论,构建截留率与传质系数线性方程,拟合传质系数与初始浓度的相关性,并建立基于操作压力和浓度预测咖啡酸截留率的数学模型,通过紫苏叶水提液验证其适用性。结果 操作压力与膜通量存在线性关系,在电荷效应和溶解-扩散效应的双重作用下,咖啡酸传质系数与初始浓度呈正相关,解离状态下的咖啡酸传质系数小于游离态及解离-游离共存态,同时,在传质系数与初始浓度呈幂函数相关的基础上,建立的纳滤传质数学模型预测的紫苏提取液中咖啡酸截留率与实验值接近。结论 咖啡酸传质系数与存在状态和初始浓度相关,以咖啡酸为例建立的纳滤分离预测模型预测效果好,为热敏性中药成分的纳滤分离提供理论支撑。
[Key word]
[Abstract]
Objective To explore the correlation of molecular state of caffeic acid from Perilla frutescens and its nanofiltration mass transfer process. Methods The pH value of solution was changed and the free-dissociation ratio was adjusted with caffeic acid as an index, the rejection and membrane flux of the corresponding initial concentration and operating pressure in different existence conditions were collected. Based on the solution-diffusion effect and charge effect in nanofiltration separation, the linear equations between the rejection and mass transfer coefficient was constructed, the correlation between mass transfer coefficient and initial concentration was established, the mathematical models which based on the operating pressure and initial concentration to predict the rejection of caffeic acid was developed and used to verify its applicability by aqueous extract of P. frutescens. Results Experiments indicated that there was a linear relationship between operation pressure and membrane flux. Besides, mass transfer coefficient and initial concentration of caffeic acid were positively correlated with each other by solution-diffusion effect and charge effect. The mass transfer coefficient of dissociated caffeic acid was less than those of free state and free-dissociation. Moreover, on the basis of power function relationship between mass transfer coefficient and initial concentration, the results showed that the predicted rejections of caffeic acid from P. frutescens water extract using mathematical model approximate well to real ones. Conclusion The mass transfer coefficient of caffeic acid is associated with existential state and initial concentration. The predicted model of nanofiltration separation has a preferable applicability to caffeic acid and provides references for nanofiltration separation, especially for heat-sensitive traditional Chinese medicine.
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[基金项目]
国家自然科学基金资助项目(81503258,81373980);江苏省自然科学基金青年基金资助(BK20151005);江苏省高等学校自然科学基金资助项目(17KJB360010)