The practical advancement of functional polymer membranes is often constrained by the leaching of active modifiers, which compromises long-term stability. To fundamentally address this issue, an amino-functionalized poly(ionic liquid)-grafted silica hybrid (PIL–SiO2–NH2) was synthesized via graft polymerization to serve as an efficient and stable modifier. With a covalently anchored polyionic liquid (PIL) shell on a rigid silica core, it was incorporated into the polyvinylidene fluoride (PVDF) matrix to prepare a positively charged blend membrane. The optimal membrane demonstrated outstanding separation performance, achieving up to 99.3% rejection rates for various dyes. More critically, the membrane showed good rejections of heavy metal ions, including Zn(II), Pb(II), and especially Cr(VI) (75.3% to >99%). The underlying mechanism, particularly for Cr(VI) removal, was evidenced by a combination of elemental distribution analysis and density functional theory (DFT) calculations, revealing the dual mechanism (electrostatic interactions and hydrogen bonding). Furthermore, comprehensive evaluations confirmed the membrane’s exceptional stability, including the robust performance in a continuous 40 h filtration of a mixed heavy metal ion solution, strong resistance to acidic/alkaline environments, and maintained separation performance after 5 cycles of EDTA-2Na-mediated desorption. This work provides a reliable material strategy for developing high-performance and durable separation membranes.
Guo et al. (2026) studied this question.