| Membrane separation is widely used in drinking water production,treatment and recycling of municipal and industrial wastewater,desalination of seawater and salt water,etc.Especially in the field of ultrafiltration,the easy processing and formability of polymer ultrafiltration membranes and their excellent separation and recyclability properties have attracted more and more attention from researchers.The morphological structure and physicochemical properties of polymer ultrafiltration membranes are the main factors affecting the separation effect,and there are still shortcomings such as low separation flux,low separation efficiency,easy pollution and difficult recycling,which limit their wide application.In order to solve the above problems,cellulose acetate(CA),deacetylated cellulose acetate(d-CA)and d-CA/polydopamine(PDA)/β-Fe OOH composite ultrafiltration membranes with different pore morphology and structure were successfully prepared by solution casting,non-solvent phase separation(NIPS)and room temperature extraction,and the effects of ultrafiltration membrane material components,processing parameters,modification methods on pore morphology,structure,separation performance and anti-pollution performance were systematically studied,including the main work:1.The CA ultrafiltration membrane was successfully prepared by solution casting,NIPS and room temperature extraction,and the effects of the preparation process parameters,molecular weight and content of the pore promoter polyethylene glycol(PEG)on the pore morphology,structure,chemical composition and surface wetting performance of the CA ultrafiltration membrane were studied by viscometer,field emission scanning electron microscope(FESEM)and contact angle measuring instrument.Pure water permeation flux,bovine serum albumin(BSA)rejection and antifouling ability were studied.The results showed that when the molecular weight and content of PEG were 10k Da and 10wt%,respectively,the pure water flux of CA10k membrane was as high as 877.5 L/m~2h.bar,the BSA rejection rate was as high as 96.5%,and the flux recovery rate(FRR)was as high as 90.9%,indicating that CA ultrafiltration membrane had broad application prospects in the field of BSA separation.2.Using simple deacetylation treatment technology,d-CA ultrafiltration membrane was successfully prepared.The pore morphology and structure,chemical composition,roughness,wettability,mechanical properties and separation properties of d-CA ultrafiltration membranes were studied by FESEM,infrared spectroscopy(FTIR),atomic force microscopy(AFM),contact angle measuring instrument and ultraviolet analyzer.The results show that the surface wettability of d-CA ultrafiltration membrane after deacetylation is significantly improved without changing the pore morphology and structure,and the water contact angle of d-CA10k ultrafiltration membrane decreases to 46.5±0.9°,and the wetting performance is optimal.In addition,the pure water flux and BSA solute retention rate of d-CA10k ultrafiltration membrane were as high as 1956.1 L/m~2h.bar and 93.5%,showing good separation performance.In addition,the FRR of d-CA10k ultrafiltration membrane was 86.6%,DRt was 35.0%,DRr was 21.6%,and DRir was 13.4%,indicating that it had good antifouling effect.These results show that d-CA ultrafiltration membrane has excellent separation performance and good anti-fouling ability,and has broad application prospects in the field of membrane separation.3.The d-CA6k/PDA/β-Fe OOH composite ultrafiltration membrane was successfully prepared by dopamine(DA)autopolymerization reaction and hydrothermal mineralization technology.The pore morphology and structure,chemical composition,mechanical properties,wettability properties,photocatalytic performance,separation performance and anti-pollution performance of d-CA6k/PDA/β-Fe OOH ultrafiltration membrane were studied by FESEM,FTIR,XRD,TGA,water contact angle,mechanical testing machine,ultraviolet spectroscopy,etc.The results showed that the d-CA6k/PDA/β-Fe OOH composite ultrafiltration membrane had good wettability.Under the illumination of visible light,methylene blue(MB)can be successfully and completely degraded by it after 20 min.The pure water flux of the composite ultrafiltration membrane was 326.5 L/m~2h.bar,and the retention rate of MB solute was as high as 96.5%.Recycling tests have shown flux recovery rates of up to 100%FRR,and the ultrafiltration membrane can be restored to its original ultrafiltration capacity after contamination.These results show that d-CA6k/PDA/β-Fe OOH composite ultrafiltration membrane has excellent separation performance,good antifouling ability and excellent photocatalytic degradation of organic dyes,and has broad application prospects in the field of membrane separation. |
