Ion Permeability of Free-Suspended Layer-by-Layer (LbL) Films Prepared Using an Alginate Scaffold

Abstract

Abstract:Layer-by-layer (LbL) films were prepared over an aperture (diameter 1-5 mm) on a glass plate to study ion permeation across free-suspended LbL films. LbL films were prepared by depositing alternating layers of poly(allylamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) on the surface of a glass plate with an aperture filled with an alginate gel, followed by dissolution of the alginate gel. PAH-PSS films prepared in this way showed permeability to inorganic salts, depending on the size and charge. Permeability to alkali metal chlorides depended on the Stokes radius of the alkali metal cations. The effect of the type of halide was negligible because of the halides' smaller ionic radii. Permeation of multivalent ions such as Ru(NH 3 ) 6 3+ and [Fe(CN) 6 ] 3− was severely suppressed owing to Donnan exclusion.

Layer-by-layer preparation of polyelectrolyte multilayer membranes for separation

“…129 Recently the transport of alkali metal halides through a free-suspended LBL lm based on poly(allylamine hydrochloride) (PAH)/PSS was studied and the permeability depended on the Stokes radius of the alkali metal cations. 130 The transport of alkali metal cations with smaller Stokes radii is faster than for cations with larger Stokes radii. The surface charge also plays a signicant role by suppressing the permeation of ions with the same charge.…”

Nanoarchitectonics for Free‐Standing Polyelectrolyte Multilayers Films: Exploring the Flipped Surfaces

“…The challenge of creating FS-PEM for ion filtration was taken up by Katsuhiko et al, with PSS/PAH on a glass plate having an aperture of ~1-5 mm by utilizing ALG gel as support. [149] ALG gel was dissolved after the deposition of PSS/PAH, acting as a filtration matrix. These FS-PEMs successfully filtered various inorganic salts based on charge/size-based exclusions.…”

“…The former is more preferred to achieve better flux, whereas the later strategy compromises the flux and limits the filtration capabilities of PEM. The challenge of creating FS‐PEM for ion filtration was taken up by Katsuhiko et al., with PSS/PAH on a glass plate having an aperture of ∼1–5 mm by utilizing ALG gel as support [149] . ALG gel was dissolved after the deposition of PSS/PAH, acting as a filtration matrix.…”

Selective exchange of alkali metal ions on EAB zeolite

“…The channel dimension of EAB zeolite framework was 3.7 Â 5.1, and the calculated maximum radium of a sphere that can diffuse along the channel was 1.77 Å [22]. In aqueous solution, the permeability into the channel depended on the Stokes radii of alkali metal ions at 25°C [23]. The Stokes radium of K + ion was 1.25 Å, smaller than the calculated maximum radium; the Stokes radium of Na + ion was 1.84 Å, comparable to the calculated maximum radium; and the Stokes radium of Li + ion was 2.38 Å, much bigger than the calculated maximum radium [24].…”