高性能聚磺酰胺耐酸纳滤复合膜的制备

Preparation of high performance polysulfonamide acid-stable nanofiltration composite membranes

聚磺酰胺(PSA)是一种常见的耐酸膜材料,通过传统界面聚合法制备的PSA薄层复合膜的通量低,限制了其应用.本文以聚砜(PSf)商品膜为基膜,以单宁酸/铁(TA/Fe)为中间层,1,6-己二胺(HDA)为水相单体,1,3,6-萘三磺酰氯(NTSC)为有机相单体,通过界面聚合法制备了PSA复合膜.通过X射线光电子能谱仪、扫描电镜、原子力显微镜对膜结构和形貌进行表征.研究结果表明,引入中间层后可以在更低的单体浓度下制备连续无缺陷的PSA层,降低了PSA层的厚度和表面粗糙度,制得的PSf-TA/Fe-PSA膜在1 MPa和25℃下,对1000 mg/L的Na2SO4溶液的通量为(18±1.2)L/(m^(2)·h),截留率为99.1%±0.1%,其性能明显高于无中间层的PSf-PSA膜[通量为(5.4±0.3)L/(m^(2)·h);Na2SO4截留率为93.3%±1.6%].TA/Fe中间层抑制了胺类单体的扩散,进而抑制了PSA表面凸起等微结构的生长,使PSA层变得更薄更光滑.酸浸泡实验表明,PSf-TA/Fe-PSA膜在200 g/L硫酸溶液中浸泡24 h后仍可以保持良好的纳滤性能.

Polysulfonamide(PSA)is a classic acid-stable membrane materials.The flux of PSA membranes prepared by traditional interfacial polymerization is low,which often hinders its application.PSA composite membranes were prepared by interfacial polymerization with polysulfone(PSf)commercial membranes as substrate membranes,tannic acid/iron(TA/Fe)as interlayer,1,6-hexanediamine(HDA)as aqueous phase monomer and 1,3,6-naphthalene trisulfonyl chloride(NTSC)as organic phase monomer.The structure and morphology of membranes were characterized by XPS,SEM and AFM.The results show that the continuous defect-free PSA layer could be prepared at lower monomer concentration by introducing the interlayer,which reduced the thickness and surface roughness of PSA layer.The water flux of PSf-TA/Fe-PSA membrane was(18±1.2)L/(m^(2)·h)and the rejection was 99.1%±0.1%under 1 MPa and 25℃for 1000 mg/L Na2SO4solution,its performance is significantly higher than PSA membranes without interlayer[the flux was(5.4±0.3)L/(m^(2)·h);Na2SO4rejection was 93.3%±1.6%].The TA/Fe interlayer restricts the amine monomer diffusion and the growth of microstructures of PSA surface bumps,rendering the PSA layer thinner and smoother.The acid immersion experiment showed that PSf-TA/Fe-PSA membrane could still maintain excellent nanofiltration performance after 24 h immersion in 200 g/L H2SO4.