UV辐照接枝制备酚酞基聚芳醚酮纳滤膜——链转移剂的作用

酚酞基聚芳醚酮(PEK-C)超滤膜的表面通过紫外辐照接枝丙烯酸(AA)可以制备对II价盐有很好截留率的亲水性纳滤膜. FTIR-ATR、表面接触角、SEM和AFM的研究结果表明, 在接枝单体溶液中加入异丙醇(i-PrOH)作为链转移剂并不影响AA在PEK-C超滤膜表面的接枝反应. 得到的改性膜同样具有优良的纳滤性能. 与不加i-PrOH的AA改性膜相比, 新合成的膜有较高的滤出液通量, 该膜对盐离子的截留率虽有所降低, 但可以通过增加接枝反应时间和辐照光源的强度来提高. i-PrOH的浓度对膜的分离性能的影响很大, 在低浓度时, 改性膜对离子的截留率会有所下降, 继续提高i-PrOH的浓度, 膜的截留率不再变化而滤出液通量会有成倍的增加, 表明链转移剂的存在可能会提高膜的接枝密度, 增加膜的表面电荷, 使膜对离子的截留率保持不变.

Preparation of PEK-C Nanofiltration Membrane by UV Irradiation Graft-Polymerization and Influence of Transfer Agent

Hydrophilic nanofiltration membranes with good retention to bivalent salts were prepared by graft polymerization of acrylic acid (AA) onto surface of cardo polyetherketone (PEK-C) ultrafiltration membranes. The influence of isopropanol (i-PrOH) as transfer agent on the graft polymerization and the performance of nanofiltration membranes were studied. The results of FTIR-ATR, contact angle, SEM and AFM showed that the presence of i-PrOH did not disturb the graft polymerization of AA. It was in favor of membrane permeation increase. Although the retention to salts was a little decreased, it could be improved by increasing the irradiation time or irradiation intensity. It was found that when the weight ratio of i-PrOH over AA was higher than 0.75, the flux of modified membrane was linearly increased with i-PrOH concentration while the retention to salt was kept unchanged. It was suggested that the transfer reaction of i-PrOH should increase grafting density and surface charge, which would be in favor of salt retention.