Purification of Water-Extraction Solution of Mulferry Root Bark with Chitosan

A major disadvantage of ethanol precipitation method used for purifying the water-extraction solution of traditional Chinese medicine is its high losing ratio of active ingredients. Therefore the technology of flocculation was used instead of the ethanol precipitation method. In this study, chitosan, which is a natural macromolecule flocculant, was used to flocculate the mulferry root bark water-extraction solution. The clarity of the water-extraction solution after flocculation and the losing ratio of flavones were taken as the guide lines to evaluate the effect of different influencing factors on flocculation. The most suitable conditions for flocculation with chitosan were obtained by experiments as follows: the chitosan concentration of 0.747 g·L-1, operation temperature of 40℃ and pH of 4.9. Comparing with the results of using the precipitation method, the flocculation method is more effective and selective for removing impurity particles and has both the advantages of increasing the clarity of the water-extraction solution and reducing the losing ratio of the active ingredients.