离子液体[Bmim]Cl改性PVDF膜的制备与性能

Preparation and properties of ionic liquid[Bmim]Cl modified PVDF membrane

为改善聚偏氟乙烯(PVDF)膜的亲水性,提高其过滤性能和抗污染性能,以离子液体1-丁基-3-甲基咪唑氯盐([Bmim]Cl)为添加剂,通过共混法和热致相分离法(TIPS)制备改性PVDF超滤膜;探究离子液体添加量对膜的水接触角、水通量、截留率和通量恢复率等的影响,并利用EDX表征[Bmim]Cl在膜表面的分布状态,通过SEM观察膜的微观结构。结果表明:[Bmim]Cl在膜表面均匀分散,改性膜的水接触角明显变小,亲水性得到较大改善;随着[Bmim]Cl质量分数提高,膜中指状孔变少,粒子堆积状态愈发明显,膜皮层厚度先减小后增大,水通量和截留率变化趋势与之相反,而通量恢复率逐渐提高;当[Bmim]Cl质量分数为0.25%时,改性膜水通量达到峰值,约为80 L/(m^2·h),比纯PVDF膜提高61.1%;当[Bmim]Cl质量分数为0.50%时,改性膜皮层最薄,截留率达到最大值95%左右,通量恢复率达86.4%,比纯PVDF膜分别提高了38.4%和17.9%。

In order to improve the hydrophilicity of polyvinylidene fluoride(PVDF)membrane and increase its filtration performance and anti-pollution performance,using the ionic liquid 1-butyl-3-methylimidazolium chloride([Bmim]Cl)as the additive,the modified PVDF ultrafiltration membranes were prepared by mixed and thermally induced phase separation(TIPS)method.The effects of ionic liquid additions on the water contact angle,water flux,retention rate and flux recovery rate of the membrane were investigated.The distribution of[Bmim]Cl on the surface of the membrane was characterized by EDX,and the microstructure of the membrane was observed by SEM.The results show that[Bmim]Cl uniformly disperses on the membrane surface,the water contact angle of modified PVDF membrane obviously decreases and its hydrophilicity is greatly improved.With the mass fraction of[Bmin]Cl increasing,in the modified PVDF membrane the finger hole decreases and the ion accumulation state is more obvious,the membrane cortex thickness first decreases and then increases,and the change trend of membrane water flux and retention rate is opposite,while the flux recovery rate increases gradually.When the mass fraction of[Bmim]Cl is 0.25%,the water flux of modified membrane reaches the peak value about 80 L(m^2·h),which is 61.1%higher than that of the pure PVDF membrane.When the mass fraction of[Bmim]Cl is 0.50%,the modified membrane has the thinnest cortex,the retention rate reaches the peak value about 95%and the flux recovery rate is 86.4%,which is 38.4%and 17.9%respectively higher than that of the pure PVDF membrane.