Layer-by-layer modification of aliphatic polyamide anion-exchange membranes to increase Cl^-/SO₄^2- selectivity

Journal Article · Sat Feb 16 00:00:00 EST 2019 · Journal of Membrane Science

DOI:https://doi.org/10.1016/j.memsci.2019.02.018· OSTI ID:1597629

Ahmad, Muhammad ^[1]; Tang, Chao ^[2]; Yang, Liu ^[2]; Yaroshchuk, Andriy ^[3]; Bruening, Merlin L. ^[2]

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1. Univ. of Notre Dame, IN (United States); University of Notre Dame
2. Univ. of Notre Dame, IN (United States)
3. ICREA, Barcelona (Spain); Polytechnic University of Catalonia, Barcelona (Spain)

Development of anion-exchange membranes (AEMs) with selectivities among anions may expand the applications of these membranes in salt separations. This work shows that layer-by-layer coating of aliphatic polyamide AEMs with poly(4-styrenesulfonate) (PSS)/protonated poly(allylamine) (PAH) films enhances Cl^-/SO₄^2- dialysis selectivities, and the extent of this enhancement depends on the source-phase salt concentrations. For a source phase containing 0.01 M NaCl and 0.01 M Na₂SO₄ and a receiving phase of 0.01 M Na₂CO₃, a (PSS/PAH)₅PSS coating (5 PSS/PAH “bilayers” capped with a layer of PSS) increases the Cl^-/SO₄^2- selectivity from 1.7 to 5.3 in diffusion dialysis and from 1.3 to 7.4 in electrodialysis. Remarkably, the diffusion dialysis selectivity of a coated membrane increases to 140 when the salt concentrations in the source phase are 0.1 M. Even with bare membranes, selectivity increases to 13 with 0.1 M source-phase salt concentrations. Moreover, AEMs coated only on the receiving side show much higher selectivities but lower fluxes than those coated only on the source side. In conclusion, partitioning experiments and modelling suggest that the increased Cl^-/SO₄^2- selectivities at high source-phase salt concentrations stem from enhanced Cl^- partitioning and electromigration that disproportionately decreases SO₄^2- flux in the AEM.

• Research Organization: Univ. of Notre Dame, IN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
• Grant/Contract Number: SC0017618
• OSTI ID: 1597629
• Alternate ID(s): OSTI ID: 1547741
• Journal Information: Journal of Membrane Science, Journal Name: Journal of Membrane Science Journal Issue: C Vol. 578; ISSN 0376-7388
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Dialysis
Ion-exchange membranes
Layer-by-layer
Polyelectrolytes
Selectivity