Strong Differential Monovalent Anion Selectivity in Narrow Diameter Carbon Nanotube Porins

Zhongwu Li, Yuhao Li, Yun Chiao Yao, Fikret Aydin, Cheng Zhan, Yunfei Chen, Menachem Elimelech, Tuan Anh Pham, Aleksandr Noy

Research output: Contribution to journalArticle

Abstract

Inner pores of carbon nanotubes combine extremely fast water transport and ion selectivity that could potentially be useful for high-performance water desalination and separation applications. We used dye-quenching halide assays and stopped-flow spectrometry to determine intrinsic permeability of three small monovalent halide anions (chloride, bromide, iodide) and one pseudohalide anion (thiocyanate) through narrow 0.8 nm diameter carbon nanotube porins (CNTPs). These measurements revealed unexpectedly strong differential ion selectivity with permeabilities of different ions varying by up to 2 orders of magnitude. Removal of the negative charge from the nanotube entrance increased anion permeability by only a relatively small factor, indicating that electrostatic repulsion was not a major determinant of CNTP selectivity. First principle molecular dynamics simulations revealed that the origin of this strong differential ion selectivity is partial dehydration of anions upon entry into the narrow CNTP channels.

Original languageEnglish (US)
Pages (from-to)6269-6275
Number of pages7
JournalACS Nano
Volume14
Issue number5
DOIs
StatePublished - May 26 2020
Externally publishedYes

Keywords

  • carbon nanotube porins
  • halide anions
  • ion channels
  • ion selectivity
  • nanofluidics

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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  • Cite this

    Li, Z., Li, Y., Yao, Y. C., Aydin, F., Zhan, C., Chen, Y., Elimelech, M., Pham, T. A., & Noy, A. (2020). Strong Differential Monovalent Anion Selectivity in Narrow Diameter Carbon Nanotube Porins. ACS Nano, 14(5), 6269-6275. https://doi.org/10.1021/acsnano.0c02423