Layer-by-layer coatings on ion exchange membranes: effect of multilayer charge and hydration on monovalent ion selectivities

Timon Rijnaarts, Dennis M. Reurink, Farzaneh Radmanesh, Wiebe M. de Vos, Kitty Nijmeijer

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Electrodialysis (ED) is an important process to desalinate brackish water, which contains scale-forming divalent ions. Hence, there is an interest in separating mono- and divalent ions. In recent years, layer-by-layer (LbL) polyelectrolyte coatings on ion exchange membranes (IEMs) have provided high monovalent ion selectivities. However, there is a lack of understanding on the structure-property relationships for polyelectrolyte multilayers for membrane applications and lack of evaluation under practical conditions. In this work, we evaluate polyelectrolyte multilayer properties by optical techniques, connect them to monovalent-selectivity using resistance measurements and upscale this to practical monovalent-selectivities for an ED unit. Excess positive poly(allyl amine) (PAH) was observed in the PAH/PSS (polystyrene sulfonate) multilayer, resulting in a positively charged multilayer. Coated multilayers with low hydrations (0.2) are able to achieve high monovalent-selectivities (of 5.7 up to 7.8) on CEMs comparable to the commercial monovalent-selective CSO (with 6.9). This enhanced selectivity was only observed for cations with LbL-coated CEMs and not for anions with LbL-coated AEMs, which we argue is due to the excess positive charge of the PAH/PSS multilayers. Finally, LbL-coatings show an improved monovalent-selectivity in ED stack experiments with artificial brackish water of 1.7 for LbL-coated CEMs compared to uncoated CEMs (with a monovalent-selectivity of 0.5).

LanguageEnglish
Pages513-521
Number of pages9
JournalJournal of Membrane Science
Volume570-571
DOIs
StatePublished - 15 Jan 2019

Fingerprint

Ion exchange membranes
Ion Exchange
Hydration
hydration
Multilayers
selectivity
Ions
membranes
coatings
Coatings
Electrodialysis
Membranes
Polycyclic aromatic hydrocarbons
Polyelectrolytes
electrodialysis
ions
polycyclic aromatic hydrocarbons
Amines
Anions
Cations

Keywords

  • Electrodialysis
  • Hydration
  • Ion exchange membranes
  • Layer-by-layer
  • Monovalent-selectivity

Cite this

Rijnaarts, Timon ; Reurink, Dennis M. ; Radmanesh, Farzaneh ; de Vos, Wiebe M. ; Nijmeijer, Kitty. / Layer-by-layer coatings on ion exchange membranes : effect of multilayer charge and hydration on monovalent ion selectivities. In: Journal of Membrane Science. 2019 ; Vol. 570-571. pp. 513-521
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abstract = "Electrodialysis (ED) is an important process to desalinate brackish water, which contains scale-forming divalent ions. Hence, there is an interest in separating mono- and divalent ions. In recent years, layer-by-layer (LbL) polyelectrolyte coatings on ion exchange membranes (IEMs) have provided high monovalent ion selectivities. However, there is a lack of understanding on the structure-property relationships for polyelectrolyte multilayers for membrane applications and lack of evaluation under practical conditions. In this work, we evaluate polyelectrolyte multilayer properties by optical techniques, connect them to monovalent-selectivity using resistance measurements and upscale this to practical monovalent-selectivities for an ED unit. Excess positive poly(allyl amine) (PAH) was observed in the PAH/PSS (polystyrene sulfonate) multilayer, resulting in a positively charged multilayer. Coated multilayers with low hydrations (0.2) are able to achieve high monovalent-selectivities (of 5.7 up to 7.8) on CEMs comparable to the commercial monovalent-selective CSO (with 6.9). This enhanced selectivity was only observed for cations with LbL-coated CEMs and not for anions with LbL-coated AEMs, which we argue is due to the excess positive charge of the PAH/PSS multilayers. Finally, LbL-coatings show an improved monovalent-selectivity in ED stack experiments with artificial brackish water of 1.7 for LbL-coated CEMs compared to uncoated CEMs (with a monovalent-selectivity of 0.5).",
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Layer-by-layer coatings on ion exchange membranes : effect of multilayer charge and hydration on monovalent ion selectivities. / Rijnaarts, Timon; Reurink, Dennis M.; Radmanesh, Farzaneh; de Vos, Wiebe M.; Nijmeijer, Kitty.

In: Journal of Membrane Science, Vol. 570-571, 15.01.2019, p. 513-521.

Research output: Contribution to journalArticleAcademicpeer-review

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T1 - Layer-by-layer coatings on ion exchange membranes

T2 - Journal of Membrane Science

AU - Rijnaarts,Timon

AU - Reurink,Dennis M.

AU - Radmanesh,Farzaneh

AU - de Vos,Wiebe M.

AU - Nijmeijer,Kitty

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