| Puerarin, one of the functional factors of pueraria isoflavonoids, has been generally used in treatment of hypertension, diabetes mellitus, liver protection and other diseases. In radix puerariae starch process, the vast majority of puerarin is washed away with wastewater and waste residue, which causes unwanted resource waste. The research of separating and purifying puerarin from radix puerariae starch wastewater has not been reported yet. Therefore, how to make full use of radix puerariae, especially to recover puerarin from wastewater is of practical importance.In this article, the reliability of content determination of puerarin in radix puerariae starch industrial wastewater by UV spectrophotometry was studied, the contents of puerarin in different parts of radix puerariae starch process were analysed, and the technology of recovering and separating puerarin from radix puerariae starch wastewater was explored. The main results of this study are as follows:The reliability of determining the content of puerarin in radix puerariae starch industrial wastewater by UV method was established.75%ethanol was choosen as solution, the linear relativity between the content of puerarin and OD value at250nm was investigated. The effect of the mixing of BSA on the measured value of puerarin with known contents was investigated; the difference between contents of puerarin in radix puerariae starch industrial wastewater which determined by UV method and HPLC method were compared. The results showed that the calibration curve of puerarin got a satisfying linear relativity in the range of2-20mg/L with R2=0.9995, RSD<1%, and the limit of detection of UV method was0.740mg/L. The P values of T Test showed that BSA did not have a significant interference on puerarin determination by UV method. The relative error between the results of UV and HPLC methods was5.0%. The determination of puerarin in radix puerariae starch industrial wastewater by UV method was easy to operate and the result was accurate.The contents of puerarin in different parts of radix puerariae starch process were determined, and dynamic monitoring of puerarin’s contents in wastewater was advanced. The contents of puerarin of radix puerariae, radix puerariae starch, waste residue, the first centrifugation wastewater and twice centrifugation wastewater were10.28mg/g(dry basis)、0.71mg/g(dry basis)、2.00mg/g(dry basis)、293.24mg/L、129.56mg/L, respectively.The puerarin in the first centrifugation wastewater was of great recycling value with a high content. Meanwhile, there was a large quantity of protein in the first centrifugation wastewater with the content of670.47mg/L.Therefore, before recovering and separating the wastewater, it is necessary to remove the protein in it. The result of dynamic monitoring showed that, the contents of puerarin changed a lot at different times. So it’s necessary to determine the content of puerarin in wastewater before processing. Puerarin showed a good heat stability and the loss of it was very low with thermal processing.Puerarin in radix puerariae starch wastewater was recycled and separated by macroporous resin and membrane separation. Flocculation was carried out in wastewater and aluminum potassium sulfate dodecahydrate was chosen as the optimal flocculant. The removal rate of protein was43.96%with added content0.1g/L at25℃.By comparing the adsorption and desorption capacities of the seven macroporous resins with different physical and chemical properties, AB-8resin showed a fast adsorption rate by reaching adsorption equilibrium in3hours. Moreover, AB-8resin offered the optimum efficiency for having the best adsorption and desorption capacities among the seven macroporous resins choosen, with the adsorption capacity and desorption ratio of12.20mg/g and95.50%, respectively. In order to optimize the separation condition, a series of eluents were used to desorb the puerarin which was adsorbed on macroporous resins. pH5.5of80%(v/v) ethanol solution performed the best eluting effect. After one run macroporous resin treatment, the puerarin content reached53.65%and the recovery yield was89.55%. AB-8resin got a long serviceable cycle which could be continuously used for5cycles. AB-8resin-column of100times(column volume5.0L) was used to recover the puerarin, the purity and recovery of the product were49.18%,85.54%, respectively. The result indicated that AB-8resin was appropriate for separating and recovering puerarin from radix puerariae starch industrial wastewater. Membrane separation was used for the further purification of puerarin. Ultrafiltration membrane of molecular weight cut-off10000Da was employed for further purification of the eluate of macroporous resin at0.15MPa,25℃. Ultrafiltration membrane was ideal for puerarin purification with the purity72.42%and recovery78.88%, respectively. SDS-PAGE electrophoretogram of separation products indicated that protein in wastewater was significantly removed by resin separation, but the effect of protein removal of membrane separation was not satisfactory. |
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