| Poly(vinylidene fluoride)(PVDF)membranes are widely used in waste watertreatment,membrane distillation,gas separation and so on,because of its excellent chemical stability,thermal stability and mechanical properties.However,due to its strong hydrophobicity on the surface,the application of PVDF membranes is limited.In the process,PVDF membrane is likely to be contaminated,the membrane flux and the service life will be reduced.Therefore,the hydrophilic modification of PVDF membrane is a in recent years.Organic-inorganic modification can combine the advantages of organic and inorganic materials to improve the membrane performance.In this paper,the experiments are based on the organic-inorganic blending modification.Zeolite 4A serve as inorganic additive to modify the performance of PVDF membranes and with N,N-dimethylacetamide(DMAc)as organic solvents.The hybrid membranes were produced by the method of immersion-precipitation phase transformation,and the structure and properties of the membranes were analyzed.Due to add zeolite 4A to PVDF directly is not good,a brush-like copolymer SMA-g-PEG was compounded of styrene/maleic anhydride(SMA)copolymerized and poly(ethylene glycol)(PEG-1000)by coupling grafting,in order to improve the compatibility of zeolite 4A and PVDF and the dispersibility of zeolite 4A in the casting solution.The amount of zeolite 4A with respectto PVDF was varied at 0,4,8,12,16 and20wt%,and theresulting membranes were designated as M0,M1,M2,M3,M4 and M5 respectively.While the samples of were designated as M0?,M1?,M2?,M3?,M4? and M5?respectively as a comparison.The compatibility of zeolite 4A/PVDF blends system and zeolite 4A/PVDF/SMA-g-PEG blends system are partially,which were determined by co-solvent method and dilute solution viscosity method.And the compatibility of zeolite 4A and PVDF will increase because of the addition of brush amphiphilic copolymer SMA-g-PEG.The surface structure and blending of the membranes were observed by scanning electron microscopy(SEM)and fourier transform infrared(FT-IR)analysis.The porosity and the retention rate of bovine serum albumin(BSA)of the membranes was tested.The pure water flux,as well as the attenuation rate and the recovery rate of membrane pure water flux was tested.The change of contact angle in 100 s of the membranes were tested.And the adsorptive property and the mechanical property of the membranes were tested.The result shows that with the increase of zeolite 4A content,the porosity,pure water flux,anti-pollution and adsorption capacity of zeolite 4A/PVDF blendingmembranes and zeolite 4A/PVDF/SMA-g-PEG blending membranes are increased,while the rejection rate is decreased.The rate of contact angle change is faster.In addition,the maximum of the mechanical properties are M4 and M4?,and M0? ~M5?changes more.Compared with M0,the porosity of M5? is 78.54%,increased by 52%.The pure water flux of M0? increased 160.4L/m2·h,and M5? is maximum 719L/m2·h;The adsorption capacity of Cu2+ of M0? increased by 48% and M5? increased by 279%.The attenuation rate of pure water flux at M5 is 12.4%,and the maximum of the recovery rate of pure water flux is 94.8%.The results show that zeolite 4A has obvious effect on improving the hydrophilicity of PVDF,and SMA-g-PEG can promote the hydrophilic modification of PVDF.The modified membranes have the adsorption capacity of zeolite4 A,which is helpful to remove heavy metal ions in waste water treatment.But reduce the rejection rate and mechanical properties of membranes.Comprehensive analysis,the performance of zeolite 4A 16%wt of zeolite4A/PVDF/SMA-g-PEG hybrid membrane is best. |
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