Separation of iron(iii), zinc(ii) and lead(ii) from a choline chloride-ethylene glycol deep eutectic solvent by solvent extraction

Stylianos Spathariotis; Nand Peeters; Karl S Ryder; Andrew P Abbott; Koen Binnemans; Sofia Riaño

doi:10.1039/d0ra06091g

Separation of iron(iii), zinc(ii) and lead(ii) from a choline chloride-ethylene glycol deep eutectic solvent by solvent extraction

RSC Adv. 2020 Sep 8;10(55):33161-33170. doi: 10.1039/d0ra06091g. eCollection 2020 Sep 7.

Authors

Stylianos Spathariotis¹, Nand Peeters², Karl S Ryder¹, Andrew P Abbott¹, Koen Binnemans², Sofia Riaño²

Affiliations

¹ School of Chemistry, University of Leicester Leicester LE1 7RH UK.
² Department of Chemistry, KU Leuven Celestijnenlaan 200F, P.O. Box 2404 B-3001 Heverlee Belgium sofia.riano@kuleuven.be.

Abstract

Deep eutectic solvents (DESs) were used as alternatives to the aqueous phase in solvent extraction of iron(iii), zinc(ii) and lead(ii). The selective extraction of iron(iii) and zinc(ii) was studied from a feed of ethaline (1 : 2 molar ratio of choline chloride : ethylene glycol) and lactiline (1 : 2 molar ratio of choline chloride : lactic acid), with the former DES being more selective. A commercial mixture of trialkylphosphine oxides (Cyanex 923, C923) diluted in an aliphatic diluent selectively extracted iron(iii) from a feed containing also zinc(ii) and lead(ii). The subsequent separation of zinc(ii) from lead(ii) was carried out using the basic extractant Aliquat 336 (A336). The equilibration time and the extractant concentration were optimized for both systems. Iron(iii) and zinc(ii) were stripped using 1.2 mol L^-1 oxalic acid and 0.5 mol L^-1 aqueous ammonia, respectively. An efficient solvometallurgical flowsheet is proposed for the separation and recovery of iron(iii), lead(ii) and zinc(ii) from ethaline using commercial extractants. Moreover, the process was upscaled in a countercurrent mixer-settler set-up resulting in successful separation and purification.