Ultrafast ion sieving using nanoporous polymeric membranes

• Published in: Nature communications Vol. 9; no. 1; pp. 569 - 9
• Main Authors: Wang, Pengfei, Wang, Mao, Liu, Feng, Ding, Siyuan, Wang, Xue, Du, Guanghua, Liu, Jie, Apel, Pavel, Kluth, Patrick, Trautmann, Christina, Wang, Yugang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.02.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 639/301/1005/190; 639/638/298; 639/925/927/1058; Alkali metals; Chemical separation; Computer simulation; Dehydration; Heavy ions; Heavy metals; Humanities and Social Sciences; Ions; Membrane permeability; Membranes; Metal ions; Molecular dynamics; multidisciplinary; Permeability; Polyethylene; Polyethylene terephthalate; Porosity; Science; Science (multidisciplinary); Selectivity; Thick films; Transport; Water filtration; Water purification
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-02941-6

The great potential of nanoporous membranes for water filtration and chemical separation has been challenged by the trade-off between selectivity and permeability. Here we report on nanoporous polymer membranes with an excellent balance between selectivity and permeability of ions. Our membranes are fabricated by irradiating 2-μm-thick polyethylene terephthalate Lumirror® films with GeV heavy ions followed by ultraviolet exposure. These membranes show a high transport rate of K + ions of up to 14 mol h −1  m −2 and a selectivity of alkali metal ions over heavy metal ions of >500. Combining transport experiments and molecular dynamics simulations with a polymeric nanopore model, we demonstrate that the high permeability is attributable to the presence of nanopores with a radius of ~0.5 nm and a density of up to 5 × 10 10  cm −2 , and the selectivity is ascribed to the interaction between the partially dehydrated ions and the negatively charged nanopore wall. Nanoporous membranes show great potential for ionic separations, but the typical trade-off between permeability and selectivity hinders their applicability. Here the authors fabricate nanoporous polymeric membranes with a high density of 0.5 nm pores and demonstrate their exceptional performance for ion sieving.