A Study On Preparation And Separation Performance Characterization Of Polysulfone Membranes Modified By Graphene Oxide-Based Composite Functional Materials

Graphene oxide has attracted wide attention of researchers in the field of membrane modification due to its high specific surface area,good hydrophilicity,excellent mechanical properties and biocompatibility.In addition,a large number of hydrophilic carboxyl,hydroxyl and carbonyl groups on the surface of graphene oxide impart many active sites,which facilitates the construction of novel composite inorganic functional materials.With the booming of membrane separation technology,the operating environment of membranes has also been diversified,and its performance requirements have become more stringent.Combining the advantages of organic membranes and inorganic functional materials to design a membrane with excellent performance is one of the research hotspots in the field of membrane separation.Herein,several composite functional materials have been successfully prepared by combining graphene oxide with different inorganic materials via chemical grafting or hydrothermal methods.They were used to modify the polysulfone ultrafiltration membrane or the polysulfone-based thin film composite nanofiltration membrane.Detailed research contents and results are as follows:?1?GO-SBA-15 composite functional material was synthesized by chemical grafting method and then blended into PSF/PVP/DMF system.The modified PSF ultrafiltration membrane was prepared by nonsolvent induce phase separation method and used to separate bovine serum albumin in water.The characterization results of GO-SBA-15 proved that SBA-15 can be uniformly dispersed in the GO layer,which relieved the agglomeration of inorganic materials inside the polymer.Modified ultrafiltration membranes possess superior pore structure,larger pore size and porosity,and higher surface hydrophilicity.The membrane separation performance experiment showed that the optimal load of GO-SBA-15 was 0.2 wt.%?G-S/M2?.The pure water flux of G-S/M2 was 641.7 L m^-22 h^-1,which was about 3 times than that of pure PSF membrane?229.2 L m^-22 h-1?.At the same time maintained a high rejection of 1 g/L BSA solution?98.22%?.In addition,the SBA-15/PSF membrane possessed better anti-pollution performance,80%of the membrane pollution was reversible,which can be recovered by a simple cleaning process and prolonged the service life of the membrane.?2?ZnO nanoparticles were hydrolyzed and deposited on SGO sheet by hydrothermal method to synthesize SGO-ZnO composite nanoparticles.The prepared SGO-ZnO was incorporated into PSF,and a modified PSF ultrafiltration membrane was prepared by nonsolvent induce phase separation method.The incorporation of SGO-ZnO not only improved the pore size,porosity and surface hydrophilicity of PSF membrane,but also greatly enhanced its separation performance.The optimum loading of SGO-ZnO was 0.2 wt.%?SG-Z/M3?,which reached the maximum pure water flux of modified ultrafiltration membrane(601.0 L m^-22 h^-1),and the rejection for BSA solution?1 g/L?was 98.25%.The FRR value was?88.6%?about 1.5 times than that of PSF membrane?58%?,indicating a significant increase in anti-contamination performance.The modified ultrafiltration membrane was further used to separate trace amounts of humic acid?HA?from water.The experiment results showed that the flux of SG-Z/M3 membrane to 10 mg/L HA was 522.8 L m^-22 h^-1,the rejection was 98.33%,and after continuously filtering 10 mg/L HA solution for 180 min,it still maintained87.9%of the original flux,which was much higher than the pure PSF film of 67.4%.?3?Support film?PSF ultrafiltration membrane?was prepraed by nonsolvent induce phase separation method.A novel thin film nanocomposite nanofiltration?TFN-NF?membrane was prepared by interfacial polymerization?IP?of polypiperazine?PIP?and trimesoyl chloride?TMC?monomers and embedding GO-SiO₂ nanocomposite in its polypiperazine amide layer.GO-SiO₂ composite nanomaterials were successfully synthesized by hydrolysis of SiO₂ nanoparticles on GO sheets.The superior performance of the TFN-NF membrane was observed in the case of 0.01 wt.%GO-SiO₂ with water flux of 43.55 L m^-22 h^-11 and salt rejection of40.7%,93.2%and 82.4%for NaCl,Na₂SO₄ and MgSO₄,respectively.Anti-fouling ability of the modified membranes tested by BSA solution filtration showed that 0.01wt.%GO-SiO₂/NF membrane possessed the best antifouling property.After continuously filtering 500 mg/L BSA solution for 180 min,the flux of bare NF membrane decreased by 33%,while this value was only 17%for 0.01 wt.%GO-SiO₂/NF membrane which confirmed that the doping of GO-SiO₂ can significantly improve the anti-fouling property of the thin film nanofiltration?TFC-NF?membrane.