Removal Mechanism And Effect Of Typical Impurities In Traditional Chinese Medicine Water-extract By Flocculation Method

Flocculation method has drawn much attention in the traditional Chinesemedicine (TCM) purification field due to its advantages of high clarity, high retentionrate of effective constituents, simple working procedure, short production period. AsTCM has many different kinds and complex constituents, the flocculation purifyingdiscipline of different water extracts also has many differences. The flocculationmechanism and discipline of tannins and protein, the typical impurities widespread inthe TCM water extracts, was studied in this paper. A series of experiments focused onthe effect of flocculant type, flocculant dosage, pH and impurity concentration onflocculation were carried out in order to summarize a widely used flocculationdiscipline and analyze the reaction mechanism between flocculants and impurities.And then a flocculant with the best flocculation performance was selected toflocculate the “Qinggan Lidan Oral Liquid” water extract, and investigate the effecton flocculation by adjusting the flocculant dosage, pH, fast stirring speed, slowstirring speed and temperature.In the tannins and protein flocculation experiments, based on the impurityremoval rate and supernatant turbidity, the effect of the flocculant dosage, pH andconcentration of solution on flocculation were investigated and the results showedthat the flocculation effectiveness firstly increased and then decreased with theincrease of the levels of factors. Meanwhile, the zeta potential of flocs always kept arising tendency with the increase of the flocculant dosage. Chitosan, chitosanquaternary ammonium salt, chitosan hydrochloride, hydroxypropyl chitosan, gelatin,and cationic polyacrylamide had the good flocculation performance on the tannic acidremoval, of which the hydroxypropyl chitosan had the best flocculation performance.The best flocculation condition of hydroxypropyl chitosan is: flocculant dosage0.085g/L, pH4.5, concentration of tannic acid10g/L, and the tannic acid removal ratecould reach to82.26%. Chitosan, chitosan quaternary ammonium salt and chitosanhydrochloride had the good flocculation performance on the protein removal, and theflocculating performance of them were ordered as follows: chitosan> chitosanquaternary ammonium salt> chitosan hydrochloride. The best flocculation conditionof chitosan is: flocculant dosage0.3g/L, pH6.0, concentration of protein7g/L, and the protein removal rate could reach to97.95%.In the flocculation experiment of the “Qinggan Lidan Oral Liquid” water extract,based on the flocculant of chitosan and the effectiveness indexes of tannins removalrate, protein removal rate and supernatant turbidity, there was always a optimal valueof different flocculating conditions to make the flocculation performance best. Theoptimal flocculation process conditions for the chitosan flocculation on the “QingganLidan Oral Liquid” water extract were: chitosan dosage1g/L, fast stirring speed250r/min, fast stirring time1min, slow stirring speed80r/min, slow stirring time12min and temperature30℃. After flocculation, the supernatant turbidity could reachto14.6NTU, tannins removal rate was73.31%, protein removal rate was68.54%, andthe retention rate of the effective constituent chlorogenic acid was93.04%. So thisflocculation method is effective and reliable.