Preparation of monoamine-incorporated polyamide nanofiltration membranes by interfacial polymerization for efficient separation of divalent anions from divalent cations
•Novel monoamines-incorporated polyamide NF membranes were developed.•Carboxyl or sulfo group of the monoamines resulted in larger negative charges.•The incorporation of the monoamines also resulted in larger MWCOs.•The membranes enabled efficient separations of sulfate ions from magnesium ions.•The...
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Veröffentlicht in: | Separation and purification technology 2020-05, Vol.239, p.116530, Article 116530 |
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Sprache: | eng |
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Zusammenfassung: | •Novel monoamines-incorporated polyamide NF membranes were developed.•Carboxyl or sulfo group of the monoamines resulted in larger negative charges.•The incorporation of the monoamines also resulted in larger MWCOs.•The membranes enabled efficient separations of sulfate ions from magnesium ions.•The membranes could be used for recovery of magnesium in desalinated seawater.
For the purpose of efficient separation of sulfate ions from magnesium ions, novel negatively-charged nanofiltration membranes were developed by incorporating the monoamines 4-aminobenozic acid, aniline-2,5-disulfonic acid monosodium salt, and iminodiacetic acid (IDA) during interfacial polymerization of piperazine (PIP) and trimesoyl chloride. PIP–amide membranes without these monomers tended to reject magnesium ions as well as sulfate ions. In contrast, incorporation of the monoamines resulted in large molecular weight cut-offs and large negative charge densities thanks to carboxyl or sulfo terminal groups of the monoamines, which enabled preferential permeation of magnesium ions while maintaining high rejection of sulfate ions. In particular, the IDA-incorporated nanofiltration membrane with an IDA to PIP + IDA mass ratio of 0.40 showed high rejection of sulfate ions with low rejection of magnesium ions even when the concentration of sodium chloride was much higher than that of magnesium sulfate. This result indicates the feasibility of the developed membrane for magnesium recovery from desalinated seawater in the electrodialysis process for table salt production. |
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ISSN: | 1383-5866 1873-3794 |
DOI: | 10.1016/j.seppur.2020.116530 |