| Abstract |
| During the extraction of metal ions from a weak acidic chloride solution by ionic liquids consisting of an organophosphorus extractant and Aliquat 336, the equilibrium pH is sometimes observed to be higher than the initial pH. To compare the hydrogen ion extraction behavior of tertiary and quaternary amines, Alamine 336, Aliquat 336 and their mixture with Cyanex 272, and an ionic liquid (prepared by mixing Cyanex 272 and Aliquat 336, R4NA) were employed in solvent extraction experiments at a pH range from 0.05 to 5. R4NA showed the highest extraction percentage of hydrogen ions. The initial pH of the chloride solution had a great effect on the extraction of hydrogen ions and the equilibrium pH value produced by these extractants. The order of hydrogen ion extraction was R4NA>Alamine 336>mixture of Alamine 336 and Cyanex 272. The addition of sodium chloride improved phase separation. The solvent extraction reaction of hydrogen ions with R4NA in the chloride solution was verified by applying a slope analysis method to the extraction data. UV-Vis and FT-IR spectra indicated a strong interaction between the hydrogen ions and R4NA during the extraction. The obtained results provide some information on the change in solution pH during the extraction of metal ions from weak acidic solution by an ionic liquid (R4NA).
(Received December 31, 2018; Accepted January 18, 2019) |
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| Key Words |
| solvent extraction, hydrogen ion, ionic liquids, aliquat 336, cyanex 272 |
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