Designing polymeric membranes with coordination chemistry for high-precision ion separations

Ryan M DuChanois; Mohammad Heiranian; Jason Yang; Cassandra J Porter; Qilin Li; Xuan Zhang; Rafael Verduzco; Menachem Elimelech

doi:10.1126/sciadv.abm9436

Designing polymeric membranes with coordination chemistry for high-precision ion separations

Sci Adv. 2022 Mar 4;8(9):eabm9436. doi: 10.1126/sciadv.abm9436. Epub 2022 Mar 4.

Authors

Ryan M DuChanois^{1

2}, Mohammad Heiranian¹, Jason Yang¹, Cassandra J Porter¹, Qilin Li^{2

3

4

5}, Xuan Zhang⁶, Rafael Verduzco^{2

5}, Menachem Elimelech^{1

2}

Affiliations

¹ Department of Chemical and Environmental Engineering, Yale University, New Haven, CT 06520-8286, USA.
² Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), 6100 Main Street, MS 6398, Houston, TX 77005, USA.
³ Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA.
⁴ Department of Materials Science and Nano Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA.
⁵ Department of Chemical and Biomolecular Engineering, Materials Science and NanoEngineering, Rice University, Houston, TX 77005, USA.
⁶ Key Laboratory of New Membrane Materials, Ministry of Industry and Information Technology; School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.

Abstract

State-of-the-art polymeric membranes are unable to perform the high-precision ion separations needed for technologies essential to a circular economy and clean energy future. Coordinative interactions are a mechanism to increase sorption of a target species into a membrane, but the effects of these interactions on membrane permeability and selectivity are poorly understood. We use a multilayered polymer membrane to assess how ion-membrane binding energies affect membrane permeability of similarly sized cations: Cu²⁺, Ni²⁺, Zn²⁺, Co²⁺, and Mg²⁺. We report that metals with higher binding energy to iminodiacetate groups of the polymer more selectively permeate through the membrane in multisalt solutions than single-salt solutions. In contrast, weaker binding species are precluded from diffusing into the polymer membrane, which leads to passage proportional to binding energy and independent of membrane thickness. Our findings demonstrate that selectivity of polymeric membranes can markedly increase by tailoring ion-membrane binding energy and minimizing membrane thickness.