Polyelectrolyte layer-by-layer deposition on nanoporous supports for ion selective membranes

Abstract

This work demonstrates that the ionic selectivity and ionic conductivity of nanoporous membranes can be controlled independently via layer-by-layer (LbL) deposition of polyelectrolytes and subsequent selective cross-linking of these polymer layers.

Evaluation of Electrodialysis Desalination Performance of Novel Bioinspired and Conventional Ion Exchange Membranes with Sodium Chloride Feed Solutions

“…The Sandia novel bioinspired cation exchange membrane (SandiaCEM) used in this study was fabricated by Percival et al [ 13 , 14 ] using a layer by layer (LbL) dip coating assembly process of electrolytes (e.g., polyacrylic acid (PAA) and polyethylimine (PEI)) with crosslinking reagents (e.g., glutaraldehyde (GA) and N-dimethylaminopropyl-N 0 -ethylcarbodimide hydrochloride (EDC)) over a bare polycarbonate (Polycarb) support membrane. The SandiaCEM demonstrated ionic selectivity, which was achieved with the use of LbL deposition of many nanostructured polyelectrolyte layers [ 13 , 14 ]. The cation transport selectivity was increased with the increasing number of polyelectrolyte layers when the polyelectrolyte or polymer layers were cross-linked with GA [ 13 ].…”

“…The SandiaCEM demonstrated ionic selectivity, which was achieved with the use of LbL deposition of many nanostructured polyelectrolyte layers [ 13 , 14 ]. The cation transport selectivity was increased with the increasing number of polyelectrolyte layers when the polyelectrolyte or polymer layers were cross-linked with GA [ 13 ]. Ionic selectivity was independent of ionic conductivity, and the ionic conductivity was decreased with the coatings but was found to regain a portion of it upon crosslinking the polyelectrolyte [ 13 , 14 ].…”

“…The cation transport selectivity was increased with the increasing number of polyelectrolyte layers when the polyelectrolyte or polymer layers were cross-linked with GA [ 13 ]. Ionic selectivity was independent of ionic conductivity, and the ionic conductivity was decreased with the coatings but was found to regain a portion of it upon crosslinking the polyelectrolyte [ 13 , 14 ]. Cross-linking the membranes also increased the intermolecular integrity of the polyelectrolyte films and inhibited the slow surface diffusion and redissolution of the polyelectrolyte films [ 13 ].…”

“…Ionic selectivity was independent of ionic conductivity, and the ionic conductivity was decreased with the coatings but was found to regain a portion of it upon crosslinking the polyelectrolyte [ 13 , 14 ]. Cross-linking the membranes also increased the intermolecular integrity of the polyelectrolyte films and inhibited the slow surface diffusion and redissolution of the polyelectrolyte films [ 13 ]. The SandiaCEM is an example of how a controllable and inexpensive method can be tailored to create ion-selective and chemically robust bioinspired membranes on porous supports for a wide range of applications.…”

“…Therefore, it is difficult to assess desalination performance of different commercially available and well-known IEMs and to recommend suitable IEMs for ED to achieve a desirable outcome (i.e., high ion‑selectivity, high salinity removal, high water recovery, low energy consumption, or low osmotic water flux). Moreover, the bioinspired IEM developed recently [ 13 , 14 ] has not been reported yet for use in ED.…”