基于离子液体共聚物荷正电膜的制备及其盐/水渗透分离性能研究

Preparation and salt/water permeation behavior of positively charged membrane based on ionic liquid block copolymer

采用可逆加成-断裂链转移聚合法合成了3种不同离子液体嵌段的共聚物PMMA-bPMEBIm-Br,并以该共聚物为成膜材料,通过溶剂蒸发法制备了致密离子液体共聚物膜,研究了共聚物的结构、膜的表面形貌以及荷电性等对膜纯水通量、盐渗透率、盐渗透通量及截留率等的影响.结果表明,该共聚物膜对NaCl、MgCl_2、CaCl_2、MgSO_4、Na_2SO_4等盐溶液均具有良好的渗透行为.相对于NaCl和MgSO_4,膜对MgCl_2的截留效果最好,截留率最高可达97%.同时,共聚物中聚离子液体链段的长度对膜的溶胀性、亲水性、荷电性及盐/水渗透性等均具有显著影响.

Ionic liquid block copolymers poly （methyl methacrylate） （PMMA）- b- poly （1- [（2- methacryloyloxy）ethyl]-3-butylimidazolium bromide） （PMEBIm-Br） with three different PMEBIm-Br block ratios were synthesized by reversible addition-fragmentation chain transfer （RAFT） polymerization method, and then used to prepare the dense membrane by solvent evaporation method. The effects of chemical structure, surface morphology and charge properties of PMMA-b-PMEBIm-Br on the membrane properties were studied. The pure water flux, salt permeability, salt flux and rejection of the membrane were tested and the results showed that PMMA-b-PMEBIm-Br membrane had good salt permeation behavior to NaCl, MgCl2, CaCl2, Na2SO4 and MgSO4 aqueous solutions. The membrane also exhibited higher rejection to MgCl2 aqueous solution than NaCl and MgSO4 and its value reached 97%. The length of PMEBIm-Br segments in the block copolymers also have great effects on the membrane performance, such as water swelling ratio, hydrophilicity, charged property and salt/water permeability.