Preparation Of Carbon Nanotube Modified PEBA Membrane And Study Of Nitrogen Dehumidification Performance

Membrane gas dehydration,with a small footprint?flexible operation?low cost?low energy consumption and other unique advantages,is a promising and attractive high-technology.Many important applications can be found in the dehydration of flue gas,natural gas dehumidification,the drying of compressed air and the storage of vegetables and fruits under protective atmosphere.In order to make full use of the advantages of flexibility of polymer materials and high selectivity of inorganic materials,the purpose of improving both selectivity and permeance was achieved by dispersing the carbon nanotubes into a continuous polymer matrix in this paper;to solve the problem of dispersion of the nanoparticles and make use of the stable ancd well-organized nanochannels of carbon nanotubes to further improve the membrane gas dehydration performance,an external direct-current electric field was applied to promote carbon nanotubes vertically aligned to the membrane surf'ace.The specific research contents are as follows:Polysulfone(PSF)membrane was used as porous supporting layer,poly(ether-block-ainide)(PEBA)as matrix material,carboxylic multi-walled carbon nanotubes(CNTs)were used as inorganic additive particles.PEBA/CNTs mixed matrix membirane with carbon nanotubes content from 0.01%to 0.06%were prepared by blending The surface morphology and structure of the PEBA/CNTs membrane were characterized by SEM,FT-IR and XRD,the results showed that the carbon nanotubes had no effect on the chemical structure of PEBA,the addition of a small amount of carbon nanotubes slightly reduccd the crystallinity of the mixed matrix membranes and further increasing the content of nanotubes can lead to the formation of micorocrystal.The effects of carbon nanotubes content on the surface hydrophilicity and nitrogen dehydration performance of membranes were investigated.With the increase of the content of carbon nanotubes,the hydrophilicity of the membrane initially increased and remained almost unchanged subsequently.The permeance and selectivity of the membrane significantly mproved,when the content of CNTs was 0.04%,the permeance of H2O was 246 GPU,and the separation factor of H2O/N2 was 315,which were 107%and 54%higher than that of the PEBA membrane respectively.The effects of diff'erent operating conditions(including permeate pressure and feed temperature)on membranes separation performance were also studied.The E-PEBA/CNTs mixed matrix membrane with carbon nanotubes content of 0.01%-0.04%were prepared by applying electric field on both sides of the membrane in the film-forming process.Raman spectroscopic?XRD and tensile test results showed that the carbon nanotubes could not only align along the direction of film thickness,but also disperse more homogeneously in the membrane under the electric field.XPS and contact angle measurements showed that the electric field force helps to improve the membrane surface hydrophilicity.The electric field could improve the nitrogen dehydration performance of the membrane,when the amount of carbon nanotubes was 0.04%,the H2O permeance of the membrane was 300 GPU;the N2 permeance was 0.9 GPU,with a separation factor of 333.