| Polyvinylidene fluoride(PVDF)has attracted wide attention for its excellent mechanical strength,thermal stability and chemical resistance.However,PVDF ultrafiltration membranes are easily contaminated by bacteria,proteins and other organic molecules,which are easily adhered to the hydrophobic membrane surface and clogged the membrane pore,resulting in a significant reduction in membrane performance,and increased energy consumption and total cost.Therefore,the preparation of hydrophilic PVDF membrane is important for the wide application of PVDF membrane in practical production.In order to improve the hydrophilicity and pollution resistance of PVDF membrane,ZnL/PVDF blend membrane,ZCN/PVDF blend membrane were prepared by phase inversion method and ZnL-PVDF supramolecular blend membrane were prepared by in situ blending method,the contents of the study are as follows:Firstly,one-dimensional chain polymer(ZnL),with high specific surface area,high porosity and regular pore structure was synthesized via solvothermal method and used as filler to prepare ZnL/PVDF blend membrane via phase inversion method.The effects of ZnL crystals on the hydrophilicity and antifouling properties of PVDF membranes were studied.The results of EDX test showed that the uniform ZnL/PVDF blend membrane was prepared,and the water flux of the blend membrane increased and then decreased with the content of ZnL,but the decrease of rejection rate was relatively small.According to the above test results,the addition of ZnL crystal can obviously improve the hydrophilicity of PVDF membrane.When the content of ZnL crystal is 0.5%,the performance of the blend membrane are the best.Secondly,ZnL@MWCNT(ZCN)crystals were synthesized via solvothermal method,and ZCN/PVDF blend membranes were prepared via phase inversion method with different content of ZCN crystals and PVDF.The membranes were analyzed and characterized by a series of tests.The effect of ZCN crystal on hydrophilic and antifouling properties of PVDF membrane was studied.The results showed that the water contact angle and water flux of ZCN/PVDF blend membrane increased firstly and then decreased,but the rejection rate of BSA decreased slightly.According to the above test results,the addition of ZCN crystal can obviously improve the hydrophilicity of PVDF membrane.When the content of ZCN crystal is 0.5%,the properties of the blend film are the best.Finally,a simple and effective method for preparing supramolecular blend membranes with good dispersibility and excellent performance is proposed,which is called in situ blending method.The ZnL-PVDF supramolecular blend membranes are prepared by this method,and analyzed and characterized by a series of tests.The hydrophilicity and antifouling properties of ZnL-PVDF supramolecular blend membrane with different contents of ZnL crystals were studied and compared with those prepared by traditional blending method when the content of ZnL crystals was 0.5%.The results showed that:the supermolecular blend membrane with uniform surface and no defect and excellent performance was prepared via this method.On the basis of the MOF/polymer blend film prepared by the traditional blending method,the in-situ polymerization method improved the dispersion of the MOF material and formed the hinge structure with the C-H-F bond,and the hydrophilicity of the blend membrane.The anti-pollution and mechanical propertie s have been greatly improved. |
