Correlation of molecular state of caffeic acid from Perilla frutescens and its nanofiltration mass transfer process / 中草药

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.