非对称聚丙烯腈纳滤膜的制备及性能研究

Preparation and performance study of asymmetric polyacrylonitrile nanofiltration membrane

聚丙烯腈(PAN)是一种价格低廉、耐候性强、化学稳定性优异的大宗合成高分子材料,已被成功应用于制备超滤和微滤膜,但在制备纳滤膜方面却面临着挑战.以国产PAN为原料,采用N,N二甲基乙酰胺(DMAc)为溶剂、四氢呋喃(THF)为共溶剂,经一步非溶剂诱导相转化过程(NIPS)制备非对称纳滤膜.通过调节液膜层相转化前的热处理温度,调控膜表面THF的挥发速率,进而控制所得PAN膜的皮层致密性,得到了纳滤膜.系统表征了所得膜的形貌、亲水性、表面流动电位等性质,测试了所得膜的水通量、对盐离子和小分子染料的截留性能.结果表明,随着对液膜层的热处理温度升高,所得膜对盐水溶液的渗透通量逐渐降低,对相应盐离子的截留率则逐渐升高,对Na_(2)SO_(4)的最高截留率可达85.6%.优化的膜对6种研究的染料水溶液过滤的产水通量处于2.14~111.5 L/(m^(2)·h),对较高相对分子质量的染料的截留率可达99.8%以上.所得膜可满足对染料水溶液的脱色应用要求.PAN有望成为一种低成本的染料废水处理纳滤膜材料.

Polyacrylonitrile(PAN)is a bulk synthetic polymer material with low price,strong weather resistance,and excellent chemical stability.PAN has been successfully applied to the preparation of ultrafiltration and microfiltration membranes,but facing challenges in preparation of nanofiltration membranes.In this paper,domestic PAN was used as raw material,N,N-dimethylacetamide(DMAc)as solvent and tetrahydrofuran(THF)as co-solvent,asymmetric nanofiltration membranes were prepared through an one-step non-solvent induced phase inversion process(NIPS).By adjusting the heat treatment temperature before the phase inversion of the liquid membrane layer,regulating the volatilization of THF on the membrane surface,the skin compactness of the PAN membrane obtained could be controlled,and nanofiltration membranes would be obtained.The morphology,hydrophilicity,surface streaming potential and other properties of the obtained membranes were systematically characterized,and the water flux and the retention of salt ion as well as small molecule dyes were tested.The results indicated that as the heat treatment temperature of the liquid membrane layer increased,the permeation flux of the resulted membranes to salt solutions gradually decreased,and the rejection to the corresponding salt ions gradually increased.And the highest rejection to Na_(2)SO_(4) was detected,reaching at 85.6%.The optimized membrane showed a flux of 2.14~111.5 L/(m^(2)·h)for the six studied dye aqueous solutions,and the rejection to dyes with relatively higher molecular weight could reach over 99.8%.The obtained membranes could meet the application requirements for the decolorization of the dye aqueous solution.PAN are expected to be a low-cost nanofiltration membrane material for dye wastewater treatment.