PVDF/PI阳离子交换膜的制备及脱盐性能

Preparation and desalination performance of PVDF/PI cation exchange membrane

通过浸没沉淀相转化的方法制备了聚偏氟乙烯(PVDF)/聚酰亚胺(PI)共混膜,使用4,4′-二氨基二苯乙烯-2,2′-二磺酸与三乙胺(DASD-TEA)溶液修饰共混膜表面,制备出PVDF/PI阳离子交换膜.探究了DASD-TEA溶液的浸泡时间、浸泡温度、DASD浓度与PI的浓度对PVDF/PI阳离子交换膜脱盐率的影响,得出最优的铸膜液配比为质量分数19.0的PVDF、1.0%的PI和80.0%的N,N-二甲基甲酰胺(DMF);最佳的DASD-TEA溶液修饰条件为质量分数0.03%的DASD,浸泡时间为10.0min,浸泡温度为50.0℃.最佳条件下,PVDF/PI阳离子交换膜的离子交换容量为0.32mmol/g,含水率为38.6%,纯水渗透率为500L/(m^2·h·MPa),接触角为81.9°,膜面电阻为2.96Ω·cm^2.采用3组膜对的电渗析装置在电压4V和流量40L/h下对2000mg/L的NaCl溶液进行了120min的脱盐实验,PVDF/PI阳离子交换膜的脱盐率为商品化阳离子交换膜的1.33倍,其脱盐性能高于商品化阳离子交换膜.

Polyvinylidene fluoride(PVDF)/Polyimide(PI)blend membrane was prepared by the immersion precipitation phase transformation method.Then the PVDF/PI membrane was modified using 4,4′-diaminostilbene-2,2′-disulfonic acid and triethylamine(DASD-TEA)aqueous solution to prepare PVDF/PI cation exchange membrane.The effects of soaking time,temperature,concentration of DASD-TEA solution and PI concentration on the desalination rate of the PVDF/PI cation exchange membrane were explored.The optimal composition of the casting solution is 19.0%PVDF,1.0%PI and 80.0%(mass fraction)N,N-dimethylformamide(DMF).The optimal conditions of the DASD-TEA modification are 0.03%DASD in the DASD-TEA aqueous solution,and soaking at 50.0℃for 10min.The ion exchange capacity of the PVDF/PI cation exchange membrane is 0.32mmol/g,the water content is 38.6%,the pure water permeability is 500L/(m^2·h·MPa),the contact angle is 81.9°,and the transmembrane resistance is 2.96Ω·cm^2.The desalination experiment was carried out in the electrodialysis device with three membrane pairs under 4Vvoltage for 120min,with 2000mg/L NaCl solution as feed at a flow rate of 40L/h.The desalination rate of the PVDF/PI cation exchange membrane is 1.33times that of the commercial cation exchange membrane.