| Membrane separation has become a mature technology and been widely used in various fields of life and production,however,the conventional membrane materials could not be used in some process of separation in extreme environment,such as the strong acid,strong alkali,strong organic solvent and high temperature.Polyphenylene sulfide(PPS)membrane is suitable usage for the separation in harsh or extreme environments because of PPS having the strong acid and alkali resistance,organic solvent corrosion resistance and high temperature resistance.Herein,PPS microfiltration membrane was used as the based membrane to prepare composite nanofiltration membrane by post modification,and nanofiltration membrane was obtained by separation functional layer establish.In addition,the preparation method of PPS hollow fiber membrane was studied,and the effects of diluent composition and post-treatment process on membrane structure and performance were discussed.The main research contents are as follows:(1)Using PPS microporous membrane as based membrane,the separation layer of graphene oxide(GO)modified by 1,2-triethoxysilyl ethane(BTESE)was constructed on the surface of based membrane by vacuum assisted self-assembly technology.The effects of BTESE concentration on the structure and properties of the composite membrane were studied systematically.The results showed that organosilicon nanoparticles(PB)were uniformly grown to realize the uniform intercalation of PB nanoparticles by in-situ polymerization between GO layers.On the one hand,the continuous hydrophilic transport channel was formed between go layers to improve the permeability of water and ethanol molecules.On the other hand,the porous structure of PB nanoparticles could effectively enhance the separation efficiency of dye molecules.(2)The composite functional layer was prepared by immobilizing the weakly crosslinked nano GO(NGO)/piperazine(PIP)self-assembly units on the surface of PPS/polydopamine/polyethyleneimine(PDA/PEI)membrane by interfacial polymerization.The effects of PIP concentration on the structure and properties of the composite functional layer were studied systematically.The results showed that the NGO sheets in the NGO/PA functional layer formed by vacuum assisted self-assembly and interfacial polymerization existed the "two channels" structure with disordered stacking,including NGO interlayer channels and small-sized vacancy channels.Under the synergistic effect of the two channels,metal ion rejection and water molecule penetration are realized.(3)The ultra-thin composite membrane with sandwich structure was prepared by molecular layer by layer assembly(m LBL).The effects of water phase monomer and the number of interfacial polymerization layers on the structure of composite membrane were studied systematically.The mechanism of membrane formation and the influence of membrane structure on performance were analyzed.The results showed that the structure and properties of the functional separation layer were quite different due to the different reaction activity of PIP and MPD with TMC and their different diffusion rate in the oil phase.The structure of functional layer synthesized from PIP was looser,and its surface was smooth,but the rejection rate was lower.The functional layer synthesized from MPD was denser,and the rejection rate was higher.(4)With DPK/BZ as diluent,PPS hollow fiber membrane was prepared by TIPS method.The effects of diluent composition and the heat stretching process on the structure and properties of PPS hollow fiber membrane were studied.The results showed that the cross-section structure was changed to a bi-continuous structure with the increase of DPK content in diluent.There was dense cortex on the outer and inner surface of PPS hollow fiber membrane,resulting in low water flux.After the hotstretching treatment of PPS hollow fiber membrane,there were tensile holes and microcrack-like holes,and the water flux and mechanical properties were improved significantly. |
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