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Issue 48, 2018
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Selective separation of heavy metal ions from dilute aqueous solutions by foams and micelles of surfactants

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Abstract

Traditional metal ion separation by surfactant foams is dependent on the interaction difference of various metal ions with surfactant monomers rather than surfactant aggregates, because the binding of metal ions with surfactant aggregates retains the metal ions in bulk solution. This kind of separation method is only effective for the metal ions with obvious differences in valence, size or coordination ability. The present study proposes a novel separation method based on the binding affinity difference of metal ions with micelles and monomers of two surfactants to selectively separate multivalent ions Cr3+, Ni2+ and Cu2+ from their dilute mixed aqueous solution. The two surfactants are single-chain surfactant sodium dodecyl sulfate (SDS) and gemini surfactant 1,3-bis(N-dodecyl-N-propanesulfonate sodium)-propane (C12C3C12(SO3)2), which show negligible synergism because they are both negatively charged and hold a significantly different self-assembling ability, thus allowing the coexistence of SDS/C12C3C12(SO3)2 micelles with SDS monomers. At first, Cr3+ ions were separated from Cu2+ and Ni2+ ions by the foam generated by the SDS monomers due to more intensive electrostatic interaction of Cr3+ ions with the SDS monomers. Afterwards Ni2+ ions were separated from Cu2+ ions by utilizing the high binding affinity of Cu2+ with the SDS/C12C3C12(SO3)2 micelles in the bulk solution and Ni2+ with the SDS monomers in the foam. This work has proved that micelles can assist the selective separation of “twin-like” metal ions Ni2+ and Cu2+ when the concentrations of monomers and micelles are properly adjusted.

Graphical abstract: Selective separation of heavy metal ions from dilute aqueous solutions by foams and micelles of surfactants

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Publication details

The article was received on 06 Oct 2018, accepted on 14 Nov 2018 and first published on 15 Nov 2018


Article type: Paper
DOI: 10.1039/C8SM02036A
Citation: Soft Matter, 2018,14, 9830-9837
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    Selective separation of heavy metal ions from dilute aqueous solutions by foams and micelles of surfactants

    Z. Liu, Y. Fan and Y. Wang, Soft Matter, 2018, 14, 9830
    DOI: 10.1039/C8SM02036A

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