Study On Modification Of Poly (Vinylidene Fluoride) Membrane And Its Application In Bioseparation

The paper focuses on hydrophilic modification of Poly(vinylidene fluoride) (PVDF) hollow fiber membranes and their application in bioseparation.Firstly, PVDF hollow membrane was treated by solutions of NaOH, NaOH/Ethanol and KMnO₄/KOH with NaHSO₄/H₂SO₄ as reductant respectively. The treated membrane surface was measured by FTIR and XPS. On the surface of the membrane there were several hydrophilic groups such as hydroxy from FTIR. XPS analysis indicated that C, O, F content of the membrane were changed from 55.4%, 38.3%, 5.6% to 55.9%, 31.1%, 13.0%. The consequence of the treated membrane performance showed that major structure of the membrane was not changed. The result of the experiment showed that hydrophilicity of the treated membrane was improved and nonspecific adsorption of the membrane was decreased.Secondly, the treated membrane was activated by Epichlorohydrin and coupled with 1,6-Hexanediamine as space arm, then the PVDF hollow fiber affinity membranes with Phe, Tip and His as ligand respectively were prepared. FTIR and XPS analysis measured the changes of chemical structure on the surface of affinity membrane with Phe as ligand. The analysis showed that affinity membrane had corresponding chemical construction such as hydroxy, amino group which indicated that the affinity membrane had spacer and linker after reactions.The affinity membrane with Phe as ligand was used for separating y-globulin from human plasma. The result of experiment showed that the affinity membrane had low nonspecific adsorption and adsorption capacity of y-globulin by the affinity membrane was 5.85 mg/g membrane under the condition of pH=7.4, 1=0.18 (ionic strength), c=1.0 mg/ml (feed liquid) while the purity of y-globulin separated from human plasma was up to 83.9%. The adsorption capacity of y-globulin by the Phe, His, Trp affinity membrane were compared and the optimum condition of y-globulin separation was studied. The result showed that the adsorption capacity and purity of y-globulin by the Phe affinity membrane was highest while purity of y-globulin by the amino acid affinity membrane was greater than 76%.Lastly, hydrophilia-modified PVDF membranes cross-linked with Chitosan were prepared. The changes of chemical structure on the membrane surface were measured by FTIR and XPS and the Test of of the membrane characteristics showed that there were some Chitosan on the membranes surface. The PVDF-chitosan membranes usedto remove cholesterin was studied. The result of experiment identified that the PVDF-chitosan membranes had low nonspecific adsorption and cholesterin adsorption of the membranes was up to 5.20 mg/g membrane, and the membrane were successfully used to adsorb cholesterin in human plasma while adsorption of the membranes for other components in human plasma should be considered in future.