Study On Impurity Removal Mechanism Of Chinese Medicinal Herb Decoction By Selective Flocculation

Compared with alcohol-precipitation method in clarification and removal of impurity, flocculation technology shows special superiority. But there is an important problem that it can flocculate available composition with impurity together. In this paper, firstly, flocculating cornel decoction and radix astragali decoction by two kinds flocculants with reserving the available composition and removing the impurity in the decoction is studied. And then mechanics of selective flocculation and the factors effect on selective flocculation are studied.In this paper, orthogonal experiments are designed to select the optimum technological conditions, and then, the effect of flocculant dosage, temperature and mixing speed on selective flocculation is studied.The results of experiments show that chitosan floccualant has good performance of selective flocculation in cornel decoction, removal rate of tannin is 90.66% and retention rate of loganin is 98.87%; In radix astragali decoction, the selectivity of flocculation is not so good as in cornel decoction, at the optimum condition, retention rate of Astragaloside is 88.39%, and removal rate of tannin is 97.46%. Chitosan hydrochlorate also show selective flocculation in cornel decoction, because the hydrochloric acid functional group in it suppressed ionization of the hydroxyl in tannin, more dosage is needed to reach optimum selective flocculation. At optimum condition, dosage of chitosan is 0.5mg/ml, and chitosan hydrochlorate is 1mg/ml. Since DMDAAC function group in PAM-DMDAAC flocculant, it has better selectivity than CPAM in flocculating tannin. APAM is amphoteric flocculant, in our test, it is the best flocculant among CPAM, APAM and PAM-DMDAAC.Start turbidity and suspended substance, surface activity of Astragaloside also impacting selective flocculation is founded in our paper.