Preparation And Performance Of Anti-Fouling High-Flux Ultrafiltration Membrane By Carbon Nanotube And PVDF

With the shortage of water resources,the problem of water pollution and the increasing water quality standards,ultrafiltration technology has drawn more and more attention due to its advantages of high separation efficiency,low energy consumption,simple process and no need to add other additives.However,membrane fouling and membrane longevity are two major problems that the ultrafiltration technology faces,seriously restricting its popularization and application.Therefore,in this paper,modified by blending method,adding amphiphilic graft copolymer PVDF-g-PEGMA and carbon nanotubes to the casting solution to improve the hydrophilic properties of PVDF ultrafiltration membrane and improve the membrane anti-pollution and through the amount.First,the amphiphilic graft copolymer PVDF-g-PEGMA was synthesized by the method of Atomic Transfer Radical Polymerization(ATRP).By phase inversion method,the PVDF and the graft copolymer were blended to prepare an ultrafiltration membrane,and the morphology of the membrane was observed with a scanning electron microscope(SEM);the contact angle was measured with a contact angle meter;the Fourier transform infrared spectrometer The structure of the membrane changes to reveal the nature of hydrophilic membrane performance;use of water flux device measured flux,pollution flux.The membrane performance was analyzed by the calculation of the indexes of flux recovery,rejection and bovine serum albumin adsorption.The pure water flux of PVDF-g-PEGMA/PVDF blends was 1382L/(m2·h),the contact angle was 63.4°,and the BSA adsorption amount was 45.25?g/cm2.When TOC concentration was 13.26mg/L sodium alginate,the removal rate of TOC was80.2%and the flux was 448L/(m2·h)when PVDF-g-PEGMA/PVDF blend ultrafiltration membrane was used.The flux was1112L/(m2·h)and the flux recovery was 80.4%.Next,0.00 g,0.01 g,0.02 g and 0.05 g of carbon nanotubes were respectively cast into the casting solution for preparing the PVDF-g-PEGMA/PVDF membrane in the weight proportions of 0.00%,0.02%,0.04%and 0.1%,in order to study the carbon nanotubes on the film performance.The morphology of the membrane was observed by scanning electron microscope(SEM).The influence of carbon nanotubes on the hydrophilicity of the membrane was investigated by means of contact angle and Fourier transform infrared spectroscopy.The flux,flux,flux recovery,Adsorption capacity of carbon nanotubes on membrane flux and anti-pollution performance.The results showed that adding CNTs without functional groups had little effect on membrane performance,but compared with adding four kinds of weight ratio membranes,adding ultrafiltration membrane prepared by adding 0.04wt.%Carbon nanotubes was better.The pure water flux of PVDF-g-PEGMA/PVDF/0.04wt.%Carbon nanotube blend ultrafiltration membrane was 1394L/(m2· h),the contact angle was 62.6° and the adsorption capacity of BSA was 31?g/cm2.PVDF-g-PEGMA/PVDF/0.04wt.%Carbon nanotubes with a total of 13.26mg/L sodium alginate water were treated with PVDF-g-PEGMA/PVDF/different weight ratios of carbon nanotube blend ultrafiltration membrane The removal rate of TOC was 80.7%,the flux was 647L/(m2·h),the pure water flux after cleaning was 1125L/(m2 · h)and the flux recovery rate was 80.7%.Then,carbon nanotubes containing four functional groups of amino group,oxy group,hydroxyl group and carboxyl group,and carbon nanotubes containing no functional group were respectively dosed in the cast solution for preparing PVDF-g-PEGMA/PVDF membrane to study the effect of different functional groups of carbon Effect of nanotubes on membrane performance.The morphology of the membrane was observed by scanning electron microscopy(SEM).The influence of carbon nanotubes with different functional groups on the hydrophilicity of the membrane was investigated by means of contact angle and Fourier transform infrared spectroscopy(FTIR)the amount.The membrane performance was analyzed by calculation of flux recovery rate,retention rate and the amount of bovine serum albumin adsorption.The results showed that the pure water flux was carbon nanotubes with hydroxyl functional groups>carbon nanotubes with carboxyl functional group>carbon nanotubes with oxygen functional group>carbon nanotubes with amino functional group>carbon nanotubes without functional group;contact angle Carbon nanotubes with hydroxyl functional groups<Carbon nanotubes with carboxyl functional groups<Carbon nanotubes with non-functional groups<Carbon nanotubes containing oxy functional groups<Carbon nanotubes containing amino functional groups;the amount of BSA adsorbed is carbon with hydroxyl functional groups Nanotubes<Carbon Functional Group-Containing Carbon Nanotubes<Functional Groupless Carbon Nanotubes<Functional Group-Containing Carbon Nanotubes<Functional Group-Containing Carbon Nanotubes.When the concentration of TOC was 13.26mg/L sodium alginate water,the removal rate of TOC by using PVDF-g-PEGMA/PVDF/CNTs with different functional groups was as follows:CNTs with hydroxyl functional group>carboxyl group-containing functional group Carbon nanotubes>Carbon nanotubes containing oxygen-containing functional groups>Carbon nanotubes containing amino functional groups>Carbon nanotubes without functional groups;flux recovery ratios sorted by size Carbon nanotubes with hydroxyl functional groups>Carbon with oxygen-containing functional groups Nanotubes>Amino-Functional Carbon Nanotubes>Carboxyl-Functional Carbon Nanotubes>Non-Functional Carbon Nanotubes.Finally,the artificial lake and lake water was treated with the mixed-membrane ultrafiltration membrane containing carbon nanotubes with hydroxyl functional groups and the mixed membrane without carbon nanotubes respectively.The SS of the lake was 234mg/L,the turbidity was 4.72NTU,CODcr was 34.67mg/L,permanganate index 18.624mg/L,UV254 0.054,ammonia nitrogen 1.05.The:flux recoveries of the two membranes were 93.8%and 87%,respectively.