一种高性能盐湖提锂纳滤膜的制备及研究

Preparation and research of a high performance nanofiltration membrane for lithium extraction from salt lake

采用界面聚合+涂层法制备了高性能盐湖提锂纳滤膜。以哌嗪(PIP)与十聚甘油混合水溶液为水相,1,3,5-苯三甲酰氯(TMC)的异构烷烃Isopar G溶液为油相,通过优化水相中十聚甘油添加量经界面聚合获得表面荷负电的疏松分离层,之后通过调整涂覆液中荷正电高聚物壳聚糖季铵盐的添加量在疏松分离层上附着性能优异的荷正电涂层,得到高性能盐湖提锂复合纳滤膜。采用Zeta电位仪、扫描电子显微镜(SEM)表征膜表面荷电性及膜表面形貌。之后考察了该复合膜对模拟卤水的提锂性能,结果表明,当水相中十聚甘油的质量分数为0.3%,涂层中壳聚糖季铵盐的质量分数为0.5%时,所制备的复合纳滤膜在操作压力2.0 MPa下,对镁锂质量比为60∶1的模拟卤水中镁锂分离因子达0.028,产水通量达20 L/(m^(2)·d)。

The interface polymerization and coating method were used to prepare high-performance salt lake lithium extraction nanofiltration membranes.A mixed aqueous solution of piperazine(PIP)and polyglycerin-10 as the aqueous phase and isoalkane(Isopar G)solution of 1,3,5-benzenetriacylchloride(TMC)as the oil phase,a loose separation layer with negative surface charge was obtained by optimizing the amount of polyglycerin-10 added in the aqueous phase.The positively charged coating with excellent performance was prepared by adjusting the addition amount of positively charged polymer chitosan quaternary ammonium salt to obtain a composite nanofiltration membrane for lithium extraction from salt lake.Zeta potentiometer and scanning electron microscope(SEM)were used to characterize the surface charge and morphology of the membrane.The lithium extraction performance of the composite membrane for simulated brine was researched.The results showed that,when the mass fraction of polyglycerin-10 in the aqueous phase was 0.3%and the mass fraction of coating polymer chitosan quaternary ammonium salt was 0.5%,the prepared composite nanofiltration membrane achieved a magnesium/lithium separation factor of 0.028 and a water yield of 20 L/(m^(2)·d)in a simulated brine with a magnesium/lithium mass ratio of 60∶1 under an operating pressure of 2.0 MPa.