Desalination Potential of Aquaporin-Inspired Functionalization of Carbon Nanotubes: Bridging Between Simulation and Experiment


Güvensoy Morkoyun A., Velioglu S., Ahunbay M. G., Ersolmaz Ş. B.

ACS APPLIED MATERIALS & INTERFACES, vol.14, no.24, pp.28174-28185, 2022 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 14 Issue: 24
  • Publication Date: 2022
  • Doi Number: 10.1021/acsami.2c03700
  • Journal Name: ACS APPLIED MATERIALS & INTERFACES
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, EMBASE, INSPEC, MEDLINE
  • Page Numbers: pp.28174-28185
  • Keywords: carbon nanotube, desalination, molecular dynamics, thin fi lm nanocomposite, biomimetic membrane, ARTIFICIAL WATER CHANNELS, REVERSE-OSMOSIS MEMBRANE, BIOMIMETIC MEMBRANES, TRANSPORT, PERMEATION, PURIFICATION, PERFORMANCE, SELECTIVITY, CONDUCTION, SEPARATION
  • Istanbul Technical University Affiliated: Yes

Abstract

Outstanding water/ion selectivity of aquaporins paves the way for bioinspired desalination membranes. Since the amino acid asparagine (Asn) plays a critical role in the fast water conduction of aquaporins through hydrogen bonding interactions, we adapted this feature by functionalizing carbon nanotubes (CNTs) with Asn. We also studied a nonpolar amino acid and carboxylate functional groups for comparison. Computation of the ideal performance of individual CNTs at atomistic scale is a powerful tool for probing the effect of tip-functionalized CNTs on water and ion transport mechanism. Molecular simulation study suggests that steric effects required for ion rejection compromise fast water conductivity; however, an Asn functional group having polarity and hydrogen bonding capability can be used to balance this trade-off to some extent. To test our hypothesis, we incorporated functionalized CNTs (f-CNTs) into the in situ polymerized selective polyamide (PA) layer of thin film nanocomposite membranes and compared their experimental RO desalination performance. The f-CNTs were found to change the separation environment through modification of cross-linking density, thickness, and hydrophilicity of the PA layer. Asn functionalization led to more cross-linked and thinner PA layer while hydrophilicity is improved compared to other functional groups. Accordingly, water permeance is increased by 25% relative to neat PA with a salt rejection above 98%. Starting from the nanomaterial itself and benefiting from molecular simulation, it is possible to design superior membranes suited for practical applications.