表面引发原子转移自由基聚合(SI-ATRP)法制备超疏水膜及其膜蒸馏应用

Preparation of superhydrophobic membrane via SI-ATRP method and its application in membrane distillation

为探究对膜结构控制行之有效的制膜法,采用表面引发原子转移自由基聚合(SI-ATRP)法制备真空膜蒸馏(VMD)用超疏水膜;以聚丙烯中空纤维膜为基膜,用过硫酸铵溶液活化膜表面,随后引发甲基丙烯酸缩水甘油酯(GMA)的多次SI-ATRP聚合,并使用全氟辛酰氯对接枝层进行修饰;之后对改性膜表面化学组成、表面粗糙度、抗润湿性、孔径及孔隙率进行了表征;同时比较了改性前后膜在高进料浓度下以及长期运行时间内的VMD性能。结果表明:改性后,膜表面SEM结果显示出明显的接枝层覆盖,且共聚焦显微镜(CSM)、水接触角(WCA)结果证实当初始单体用量为膜质量的20倍时,制得表面具备多孔拓扑结构,水接触角高达179.0°的超疏水膜L-PP-20;孔径分布及孔隙率结果显示L-PP-20的孔径分布变窄、孔隙率增大;通过短期高进料浓度及21 h的长期VMD实验,表明L-PP-20的短期性能尚可,长期平均通量为11.01 kg/(m^(2)·h),超出原膜4.53 kg/(m^(2)·h),通量及截留率长期稳定性好,为SI-ATRP法制膜在VMD中提供良好范例。

In order to explore an effective method for controlling membrane structure,surface-initiated atom transfer radical polymerization(SI-ATRP)was employed to prepare superhydrophobic membranes for vacuum membrane distillation(VMD).The polypropylene hollow fiber membrane was used as the base membrane,the surface was activated with ammonium persulfate solution,followed by multiple SI-ATRP polymerizations of glycidyl methacrylate(GMA),and the graft layer was modified with perfluorooctanoyl chloride.Then,the surface chemical composition,surface roughness,anti-wetting property,pore size and porosity of the modified membrane were characterized.At the same time,the VMD performance of the modified membrane under high feed concentration and long-term running time was compared.The results showed that after modification,the SEM images of the membrane surface demonstrated prominent graft layer coverage.The results of CSM and WCA reveal that when the initial monomer content was 20 times the mass of membranes,the surface exhibited porous topology and the water contact angle was as high as 179.0°,indicating superhydrophobic membrane was acquired,the corresponding sample was L-PP-20.The pore size distribution and porosity suggested that the pore size distribution of L-PP-20 was narrowed and the porosity increased.When the short-term high feed concentration and 21 h long-term VMD were tested,the results indicated that the short-term performance of L-PP-20 was acceptable and long-operation average flux was 11.01 kg/(m^(2)·h),exceeding the original membrane by 4.53 kg/(m^(2)·h).The long-term stability of flux and rejection rate was excellent.L-PP-20 set a good example for the application of SI-ATRP method in VMD.