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dc.contributor.authorCheng, Wei
Liu, Caihong
Tong, Tiezheng
Epsztein, Razi
Sun, Meng
Verduzco, Rafael
Ma, Jun
Elimelech, Menachem
dc.date.accessioned 2018-10-31T18:20:48Z
dc.date.available 2018-10-31T18:20:48Z
dc.date.issued 2018
dc.identifier.citation Cheng, Wei, Liu, Caihong, Tong, Tiezheng, et al.. "Selective removal of divalent cations by polyelectrolyte multilayer nanofiltration membrane: Role of polyelectrolyte charge, ion size, and ionic strength." Journal of Membrane Science, 559, (2018) Elsevier: 98-106. https://doi.org/10.1016/j.memsci.2018.04.052.
dc.identifier.urihttps://hdl.handle.net/1911/103249
dc.description.abstract We fabricatedᅠpolyelectrolyteᅠmultilayerᅠ(PEM)ᅠnanofiltrationᅠ(NF) membranes using a layer-by-layer (LbL) method for effective removal of scale-forming divalent cations (Mg2+, Ca2+, Sr2+, and Ba2+) from feedwaters with different salinities. Twoᅠpolymersᅠwith opposite charges, polycation (poly(diallyldimethylammonium chloride), PDADMAC) and polyanion (poly(sodium 4-styrenesulfonate), PSS), were sequentially deposited on a commercialᅠpolyamideᅠNF membrane to form a PEM. Compared to pristine and PSS-terminated membranes, PDADMAC-terminated membranes demonstrated much higher rejection of divalent cations and selectivity forᅠsodiumᅠtransport over divalent cations (Na+/X2+) due to a combination of both Donnan- and size-exclusion effects. A PDADMAC-terminated membrane with 5.5 bilayers exhibited 97% rejection of Mg2+ᅠwith selectivity (Na+/Mg2+) greater than 30. We attribute the order of cation rejection (Mg2+ᅠ> Ca2+ᅠ> Sr2+ᅠ> Ba2+) to the ionic size, which governs both the hydration radius and hydration energy of the cations. The ionic strength (salinity) of the feed solution had a significant influence on both water flux and cation rejection of PEM membranes. In feed solutions with high ionic strength, abundant NaCl salt screened the charge of the polyelectrolytes and led to swelling of the multilayers, resulting in decreased selectivity (Na+/X2+) and increased water permeability. The fabricated PEM membranes can be potentially applied to the pretreatment of mild-salinity brackish waters to reduce membrane scaling in the mainᅠdesalinationᅠstage.
dc.language.iso eng
dc.publisher Elsevier
dc.rights This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier.
dc.title Selective removal of divalent cations by polyelectrolyte multilayer nanofiltration membrane: Role of polyelectrolyte charge, ion size, and ionic strength
dc.type Journal article
dc.citation.journalTitle Journal of Membrane Science
dc.contributor.org Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment
dc.subject.keywordNanofiltration
Polyelectrolyte multilayer
Divalent cation removal
Ionic strength
Scaling control
dc.citation.volumeNumber 559
dc.type.dcmi Text
dc.identifier.doihttps://doi.org/10.1016/j.memsci.2018.04.052
dc.type.publication post-print
dc.citation.firstpage 98
dc.citation.lastpage 106


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