Metal-Organic-Framework-based nanofiltration membranes for selective multi-cationic recovery from seawater and brines

Carmelo Morgante, Xianzheng Ma, Xinxin Chen, Deyong Wang, Vittorio Boffa*, V Stathopoulosd, J. Lopez, J. Cortina, A. Cipollina, A. Tamburini, G. Micale

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

2 Citations (Scopus)
64 Downloads (Pure)

Abstract

Nanofiltration (NF) is gaining a role of increasing importance in Zero Liquid Discharge (ZLD)/Minimal Liquid Discharge (MLD) systems, enhancing the efficiency of downstream technologies to recover valuable minerals from seawater and brines. However, often the purity of the recovered minerals does not meet market specifications, making ZLD/MLD currently economically unfeasible. To such end, in this study, a novel positively charged NF membrane was developed to enhance magnesium and calcium selectivity. The membrane comprised: (i) an ultrafiltration substrate and (ii) an active layer that incorporated NH2-MIL-101(Al) and ZnO nanoparticles in a chitosan matrix. The influence of different loadings of NH2-MIL-101(Al) and ZnO on membrane structure, selectivity and water permeability was investigated. Initial filtration tests with single-salt solutions at 1000 ppm (NaCl, Na2SO4, MgCl2, CaCl2) showed that the membrane with 35%wt of ZnO presented the highest rejections of MgCl2 (90.10%) and CaCl2 (86.49%). Selectivity towards MgCl2 and CaCl2 was higher than those of commercial membranes (NF90 and NF270) and the positively charged membranes introduced in recent literature. The novel synthesized membrane in this work was also tested with synthetic seawater and brine at a trans-membrane pressure of 30 bar. Results highlighted the intriguing competitiveness of the novel membrane in terms of magnesium and calcium selectivity with NF90 and NF270 within the field of both seawater and brine valorization.
Original languageEnglish
Article number121941
JournalJournal of Membrane Science
Volume685
ISSN0376-7388
DOIs
Publication statusPublished - 5 Nov 2023

Keywords

  • Brine valorization
  • Critical raw materials
  • Metal-organic-framework
  • Mineral recovery
  • Zinc oxide

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