Positively charged nanofiltration membrane synthesis, transport models, and lanthanides separation

Francisco Léniz-Pizarro, Chunqing Liu, Andrew Colburn, Isabel C. Escobar, Dibakar Bhattacharyya

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

The design and understanding of rejection mechanisms for both positively and negatively charged nanofiltration (NF) membranes are needed for the development of highly selective separation of multivalent ions. In this study, positively charged nanofiltration membranes were created via an addition of commercially available polyallylamine hydrochloride (PAH) by conventional interfacial polymerization technique. Demonstration of real increase in surface zeta potential, along with other characterization methods, confirmed the addition of weak basic functional groups from PAH. Both positively and negatively charged NF membranes were tested for evaluating their potential as a technology for the recovery or separation of lanthanide cations (neodymium and lanthanum chloride as model salts) from aqueous sources. The NF membranes with added PAH performed high and stable lanthanides retentions, with values around 99.3% in mixtures with high ionic strength (100 mM, equivalent to ~6000 ppm), 99.3% rejection at 85% water recovery (and high Na+/La3+ selectivity, with 0% Na+ rejection starting at 65% recovery), and both constant lanthanum rejection and permeate flux at even pH 2.7. Donnan steric pore model with dielectric exclusion elucidated the transport mechanism of lanthanides and sodium, proving the potential of high selective separation at low permeate fluxes using positively charged NF membranes.

Original languageEnglish
Article number118973
JournalJournal of Membrane Science
Volume620
DOIs
StatePublished - Feb 15 2021

Bibliographical note

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • DSPM-DE
  • Lanthanides separation
  • Nanofiltration
  • Positively charged membrane
  • Zeta potential

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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