Polyethylenimine (PEI) cross-linked P84 nanofiltration membranes were successfully developed through a facile stirring cross-linking method. The separation performance of the membrane was tailored by changing the concentration of the P84 casting solution. A systematic characterization, including chemical structure, surface morphology, surface charge, and separation performance, was carried out. Nanofiltration membranes with a high positive charge and hydrophilic surface were successfully fabricated. All the PEI cross-linked membranes showed high isoelectric points at pH from 8 to 8.9 and a mean pore radius from 0.389 to 0.474 nm. Under the influence of the Donnan effect and size exclusion, the 20%P84/PEI membrane showed an excellent water permeance of 27.7 ± 1.5 L m⁻² h⁻¹ bar⁻¹ and a high rejection (>90%) for single-component heavy metal salts (ZnCl₂, PbCl₂, Ni(NO₃)₂ and Cu(NO₃)₂). A variety of mixed salt separation performance tests were performed. These results clearly indicate that the 20%P84/PEI and 22%P84/PEI membranes have a huge potential to remove and concentrate copper ions from aqueous solutions. In particular, the 24%P84/PEI membrane is promising in the selective removal of various heavy metals from highly saline water.

聚乙烯亚胺（PEI）交联P84纳滤膜通过简便的搅拌交联方法研制成功。通过改变 P84 浇铸溶液的浓度来调整膜的分离性能。进行了系统表征，包括化学结构、表面形态、表面电荷和分离性能。成功制备了具有高正电荷和亲水表面的纳滤膜。所有 PEI 交联膜在 pH 值为 8 至 8.9 时均显示出高等电点，平均孔径为 0.389 至 0.474 nm。在唐南效应和尺寸排阻的影响下，20%P84/PEI 膜表现出优异的透水性，为 27.7 ± 1.5 L m ^-2  h ^-1  bar^-1和对单组分重金属盐（ZnCl ₂、PbCl ₂、Ni(NO ₃ ) ₂和 Cu(NO ₃ ) ₂）的高去除率 (>90% )。进行了多种混合盐分离性能测试。这些结果清楚地表明，20% P84/PEI 和 22% P84/PEI 膜具有从水溶液中去除和浓缩铜离子的巨大潜力。特别是，24% P84/PEI 膜在选择性去除高盐水中的各种重金属方面很有前景。