Tuning thin-film composite reverse osmosis membranes using deep eutectic solvents and ionic liquids toward enhanced water permeation

Soulmaz Seyyed Shahabi, Najmedin Azizi*, Vahid Vatanpour

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

Deep eutectic solvents (DES) have invoked an enormous interest as inexpensive, greener and biorenewable solvents and additives with promising applications. In the present study, we investigated a choline chloride-urea based DES and a series of commercial ionic liquids (ILs) as additives including 1-hexyl-3-methyl-imidazolium chloride, 3-methyl-1-octyl-imidazolium tetra fluoroborate, N-butyl pyridinium and betaine monohydrate to modify the polyamide (PA) layer of reverse osmosis (RO) membranes. The ILs were selected from various categories to find better of them in RO modification. Accordingly, the DES and ILs with different concentrations were added to the MPD aqueous solution. The results of SEM and AFM analyses showed a smoother surface for the DES and ILs-modified membranes. The membrane modified with 1 wt% of DES achieved the pure water flux of 56.7 L/m2h and the observed salt rejection of 96.4%, exhibiting a 27% and 3% increase in water flux and salt rejection, respectively, as compared with the unmodified membrane. Among the used ILs, the membranes modified with N-butyl pyridinium and betaine monohydrate showed the best desalination performance, with the pure water flux of 78.9 L/m2h and 51.7 L/m2h and the NaCl rejection of 97.3% and 94.4%, respectively. Also, choline hydroxide IL was used for the surface modification of the SO3H-g-C3N4 nanosheets to examine efficiency of ILs on membranes, when located on nanosheet surface. The results of the desalination experiments showed that the incorporation of the modified nanosheets at low concentrations was effective in enhancing the membrane performance. Although increasing the concentrations of nanosheets in the PA layer of the membranes resulted in the enhanced water flux, the salt rejection was decreased.

Original languageEnglish
Article number118267
JournalJournal of Membrane Science
Volume610
DOIs
Publication statusPublished - 1 Sept 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 Elsevier B.V.

Keywords

  • Deep eutectic solvent
  • Desalination
  • g-CN nanosheets
  • Ionic liquids
  • Reverse osmosis

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