Preparation And Characterization Of Novel Solvents-Resistant Nanofiltration Membrane Based On Chloromethylated Polysulfone

Solvent resistant nanofiltration(SRNF)shows quite good usage in many fields,the development of high-performance SRNF membranes has become a hot topic in membrane separation.Polysulfone(PSF)is one of thermoplastics,and process the excellent chemical resistance and thermal stability.In this investigation,the effects of film formation process on the morphology of membrane were studied,which can ultimately lead to different separation properties.The relationship between membranes morphology and their performance was clarified by studying their crosslinking mechanism,microstructure and separation performance.The structure,composition and preparation of high performance solvent resistance nanofiltraion membrane were established.The detailed work is as follows:(1)Design and fabrication of CMPSF membrane material,and the structure was confirmed by NMR and IR.The CMPSF membranes were prepared via phase inversion.The relationship between membranes morphology and their separation performance was investigated.The results showed that with the increased polymer concentration in the cast solution,the number of macrovoids gradually decreased and the skin layer became denser.Accordingly,permeance of solvent decreased,but no obvious change was found in the rejection of prepared CMPSF membrane(2)To enhance the chemical stability and separation properties of CMPSF membranes,the internal cross-linking networks are constructed by reacting imidazole with CMPSF.The crosslinking networks can dramatically improve the solvent stability of the CMPSF membranes and the performance of the membrane is tuned via changing the polymer concentration from 20 wt%to 28 wt%.The crossed CMPSF solvent resistant nanofiltration membranes showed more than 92%rejection on RB,CV and BTB in acetone and dimethylacetamide.Specially,the Rose Bengal rejection was as high as 96%in dimethylacetamide.(3)The morphology of CMPSF nanofiltration membranes can be tuned by controlling the concentration of volatile co-solvent tetrahydrofuran(THF),and the membrane showed good separation performance with the 20%THF in cast solution.In addition,the morphology of CMPSF membranes can be tuned via controlling the evaporation time of co-solvent.With increasing the evaporation time of volatile solvent,the thickness of membrane surface layer increased.The membranes showed higher rejection and lower permeance.