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Issue 14, 2017
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Effect of spacer length of ionic liquid-type imidazolium gemini surfactant-based water-in-oil microemulsion for the extraction of gold from hydrochloric acid

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Abstract

Microemulsions consisting of ionic liquid-type imidazolium gemini surfactants with different spacer lengths ([C14-n-C14im]Br2, n = 2, 4, 6), cyclohexane, n-hexyl alcohol and hydrochloric acid solution, were investigated for Au(III) extraction. [C14-n-C14im]Br2 in the microemulsion played a dual role as surfactant and extractant. The extraction efficiency (E%) of the [C14-n-C14im]Br2/cyclohexane/n-hexyl alcohol/HCl microemulsion system for Au was above 99% under optimal conditions. The results of our study indicated that the Au(III) extraction ability of the three different [C14-n-C14im]Br2 with different spacer lengths was better with longer a spacer. The mechanism for the Au(III) extraction by [C14-n-C14im]Br2 was confirmed to be based on an anion-exchange process by the continuous variation method and spectroscopic analysis (UV-Vis, FT-IR, 1H-NMR). The FT-IR spectra indicated that the better extraction ability of [C14-n-C14im]Br2 for Au(III) was positively correlated with the spacer length, due to a less significant steric effect of the methylene groups in surfactants with longer spacers. The electric conductivity values of the [C14-n-C14im]Br2 microemulsions indicated that surfactants with longer spacers can ionize to a higher extent to give more [C14-n-C14im]2+ cations and Br− anions, thus promoting anion-exchange and further increasing E%.

Graphical abstract: Effect of spacer length of ionic liquid-type imidazolium gemini surfactant-based water-in-oil microemulsion for the extraction of gold from hydrochloric acid

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Publication details

The article was received on 15 Feb 2017, accepted on 26 May 2017 and first published on 26 May 2017


Article type: Paper
DOI: 10.1039/C7NJ00551B
Citation: New J. Chem., 2017,41, 6180-6186
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    Effect of spacer length of ionic liquid-type imidazolium gemini surfactant-based water-in-oil microemulsion for the extraction of gold from hydrochloric acid

    Z. Xiang, Y. Zheng, H. Zhang, Y. Yan, X. Yang, X. Xin and Y. Yang, New J. Chem., 2017, 41, 6180
    DOI: 10.1039/C7NJ00551B

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