Most of the ion exchange membranes distinguished monovalent ions from the multivalent ions according to the charge difference, but scarcely had selectivity to the specific ions. In order to effectively separate potassium ions from seawater containing more than 30 times sodium ions, potassium ion-sieve composite membranes with specific selectivity to potassium ions had been synthesized in this paper. The potassium ion sieve was successfully synthesized on the flat α-Al₂O₃ membrane by secondary hydrothermal method to form potassium ion sieve composite membrane. Then, the results of SEM, XRD and EDS showed that the potassium ion sieve had been successfully bonded with base membrane. The results of electrodialysis experiments showed that the ionic perm-selectivity were α (K/Na) = 7.62, α (K/Mg) = 68.43 and α (K/Ca) = 162.92 respectively, which indicated that the composite membrane had special selectivity for potassium ions. The composite membrane had been evaluated under different voltages and temperatures. As the voltage increased, the ion flux and the perm-selectivity to potassium were all improved. Moreover, with the increase of temperature, the ion flux increased but the selectivity to potassium decreased. The separation performance of the composite membrane was studied by using equimolar solution (containing K⁺, Na⁺, Ca²⁺, Mg²⁺), seawater and twice concentrated seawater as the test solutions, and the results had exhibited that the composite membrane had good application performance in extracting potassium from seawater.

大多数离子交换膜根据电荷差将一价离子与多价离子区分开，但几乎没有对特定离子的选择性。为了有效地将钾离子从钠离子含量超过30倍的海水中分离出来，本文合成了对钾离子具有特定选择性的钾离子筛复合膜。钾离子筛平上成功地合成的α-Al ₂ ö ₃膜通过二次水热法形成钾离子筛复合膜。然后，SEM，XRD和EDS的结果表明，钾离子筛已成功地与基膜结合。电渗析实验结果表明，离子渗透选择性为α（K / Na）= 7.62，α（K / Mg）= 68.43，α（K / Ca）= 162.92，表明复合膜具有特殊的选择性。用于钾离子。已经在不同的电压和温度下评估了复合膜。随着电压的增加，离子通量和对钾的渗透选择性均得到改善。此外，随着温度的升高，离子通量增加，但对钾的选择性降低。用等摩尔溶液（含钾）研究复合膜的分离性能。⁺，钠⁺，钙²⁺，镁²⁺），海水和两次浓缩海水作为试验溶液，结果显示出了该复合膜具有在从海水中提取钾良好的应用性能。