Carson, Innis

Fischmann, Adam J.

Jakovljevic, Boban

Love, Jason B.

Morrison, Carole A.

Moser, Michael

Soderstrom, Matthew D.

Tasker, Peter A.

English

The mode of action of iron(III) uptake from sulfate solutions by the commercial extractant CYANEX®272, bis(2,4,4-trimethylpentyl)phosphinic acid, has been studied using conventional solvent extraction methods, together with 31P{1 H} NMR spectroscopy, electrospray ionisation mass spectrometry, and DFT calculations that have not previously been used to analyse the content of the ISOPAR M water-immiscible phase. The maximum Fe-loading recorded was 177% of the theoretical maximum, based on the formation of an Fe(III) complex [Fe(L)3] with a 1:3 molar ratio of Fe to phosphinate (L). Inductively coupled plasma optical emission spectroscopy (ICP-OES) indicates that sulfate or hydrogen sulfate ions are co-extracted in a 1:2 molar ratio with iron across the whole of the Fe-loading range, which helps to account for the loadings being greater than 100% of the theoretical value. 31P{1 H} NMR spectroscopy indicates that the limiting factor in Fe-loading is the availability of uncomplexed CYANEX®272 (sulfate is present in large excess). In contrast to the behaviour of Co(II) and Zn(II) extraction by CYANEX®272, there is no evidence for the formation of polymeric Fe(III) complexes and highly viscous solutions at high metal loadings. The identity of the extracted species is likely to be a polynuclear Fe(III) sulfate complex

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Co-extraction of Iron and Sulfate by Bis(2,4,4-trimethylpentyl)phosphinic Acid, CYANEX®272

https://www.research.ed.ac.uk/files/140115883/20200319_Morrison_Fe_CYANEX_272.pdf

Co-extraction of Iron and Sulfate by Bis(2,4,4-trimethylpentyl)phosphinic Acid, CYANEX®272

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