碳纳米管改性PEBA膜的制备及氮气脱湿性能

Preparation and nitrogen dehumidification of PEBA membranes modified by MWCNTs

为提高膜法氮气脱湿性能,以聚砜(PSF)超滤膜为多孔支撑层,以聚醚嵌段酰胺(PEBA)为活性分离层,以羧基化碳纳米管(MWCNTs-COOH)为添加剂,以正丁醇为溶剂,通过涂覆法制备PEBA/MWCNTs-COOH混合基质膜,并研究碳纳米管含量对膜表面亲水性和氮气脱湿性能的影响,以及不同操作条件对膜分离性能的影响.结果表明:碳纳米管对PEBA的化学结构无影响,添加少量碳纳米管会稍微降低混合基质膜的结晶度,进一步增加碳纳米管含量会导致微晶产生;随着羧基化碳纳米管含量增加,膜表面亲水性增加,膜的渗透性和选择性均有显著提高,当MWCNTs-COOH质量分数为0.04%时,水蒸汽的渗透速率为246 GPU(1 GPU=3.35×10^(-9) mol/(cm^2·s·kPa)),H_2O/N_2分离因子为315,比无添加膜分别提高了107%和54%;随着渗透侧压力减小,H_2O/N_2分离因子增加,随着原料温度升高,H_2O/N_2分离因子下降.

In order to improve the nitrogen dehumidification performance of membrane,the mixed matrix membranes(MMMs)PEBA/MWCNTs-COOH were fabricated via coating method with polysulfone(PSF)ultrafiltration membrane as the porous supporting layer,poly(ether-block-amide)(PEBA)as the material of active layer,the carboxylic multi-walled carbon nanotubes(MWCNTs-COOH)as the filler,n-butyl alcohol as the solvent,the effects of MWCNTs-COOH concentration in a membrane on the hydrophilicity and nitrogen dehumidification property of the MMMs and the impacts of operating conditions on the permeation performance of the MMMs were explored.The results indicated that the addition of MWCNTs-COOH had no effect on the chemical structure of PEBA,a small amount of carbon nanotubes decreased the crystallinity of the mixed matrix membrane slightly,and further increasing the content of the carbon nanotubes caused the formation of microcrystal.It was found that with an increase in the content of carbon nanotubes,the hydrophilicity of the membrane increased,and both the permeance and separation factor of H2O/N2 were significantly improved.When the mass fraction of MWCNTs-COOH was 0.04%,the water permeance reached 246 GPU(1 GPU=3.35×10^-9 mol/(cm^2·s·kPa))and the separation factor of H2O/N2 was 315,compared with those of the pure PEBA membrane,which were increased by 107%and 54%,respectively; as the permeate pressure decreased,the separation factor of H2O/N2 increased,and as the raw material temperature increased,the separation factor of H2O/N2 decreased.