Non-aqueous solvent extraction of indium from an ethylene glycol feed solution by the ionic liquid Cyphos IL 101: speciation study and continuous counter-current process in mixer–settlers

Abstract

Speciation studies give insight into the mechanism of non-aqueous solvent extraction of indium from ethylene glycol solution by the ionic liquid Cyphos IL 101.

Nonaqueous Solvent Extraction for Enhanced Metal Separations: Concept, Systems, and Mechanisms

“…A similar NASX system, using Cyphos IL 101 instead of Aliquat 336, was applied to the separation of In­(III) and Zn­(II). The extraction of In­(III) from EG solution was more efficient than from aqueous solution, whereas the extraction of Zn­(II) was less efficient, leading to enhanced separation of these two elements . The species of In­(III) in EG was found to change from the bridging (InCl 3 ) 2 (EG) 3 or mononuclear (InCl 3 )­(EG) 2 complex at low LiCl concentrations to [In­(EG)­Cl 4 ] − at high LiCl concentrations .…”

Liquid-Liquid Extraction of Indium(III) from the HCl Medium by Ionic Liquid A327H+Cl− and Its Use in a Supported Liquid Membrane System

“…[In] aq,e (17) where [In] org,e and [In] aq,e are the indium concentrations in the equilibrated organic and aqueous phases, respectively.…”

“…− [20]), or chloride-rich deep eutectic solvents [21]; in all the above cases, the extraction efficiencies of the different extractants were high, i.e., exceeding 95%, though the experimental conditions vary from one investigation to another, i.e., pH 2 [13] against a medium rich in HCl [15,19], a type of an acidic medium, i.e., HCl [16] against sulphuric acid [20], and varying extractant concentrations [13][14][15][16][17][18][19][20][21]. Ionic liquids are a group of chemicals, which are considered of interest in the field of liquid-liquid extraction due to the ability to react with metal compounds [22][23][24][25], and also due to their properties, such as low melting point, nonflammability, high thermal stability, and low vapor pressure; due to their non-volatile nature, they are called "green solvents", though there are voices claiming about their harmfulness and the toxicity associated with some of their components.…”

“…Hydrometallurgical recovery of indium from a material containing it requires some steps: the first is to leach the solid product, and in the case of indium, as expected, mineral acids and aqua regia is the media to dissolve the element [3,4], though incursions in the use of bioleaching [5] and deep eutectic solvents [6] are also known. Once dissolved, the approaches to recover the metal include ion exchange [7], precipitation [8], membranes [9,10], counter-current foam separation [11], electrowinning [12], cementation [4], but the main interest seemed to be in the use of solvent extraction using conventional extractants, such as 8-hydroxyquinoline derivatives [13], D2EHPA [14], TBP (tributyl phosphate [15], methylimino-dioctylacetamide (MIDOA) [16], ionic liquids (Cyphos IL101 and Aliquat 336 [17], Cyphos IL104 [18], A324H + Cl − [19], PJMTH + HSO 4…”

“…Hydrometallurgical recovery of indium from a material containing it requires some steps: the first is to leach the solid product, and in the case of indium, as expected, mineral acids and aqua regia is the media to dissolve the element [ 3 , 4 ], though incursions in the use of bioleaching [ 5 ] and deep eutectic solvents [ 6 ] are also known. Once dissolved, the approaches to recover the metal include ion exchange [ 7 ], precipitation [ 8 ], membranes [ 9 , 10 ], counter-current foam separation [ 11 ], electrowinning [ 12 ], cementation [ 4 ], but the main interest seemed to be in the use of solvent extraction using conventional extractants, such as 8-hydroxyquinoline derivatives [ 13 ], D2EHPA [ 14 ], TBP (tributyl phosphate [ 15 ], methylimino-dioctylacetamide (MIDOA) [ 16 ], ionic liquids (Cyphos IL101 and Aliquat 336 [ 17 ], Cyphos IL104 [ 18 ], A324H + Cl − [ 19 ], PJMTH + HSO 4 − [ 20 ]), or chloride-rich deep eutectic solvents [ 21 ]; in all the above cases, the extraction efficiencies of the different extractants were high, i.e., exceeding 95%, though the experimental conditions vary from one investigation to another, i.e., pH 2 [ 13 ] against a medium rich in HCl [ 15 , 19 ], a type of an acidic medium, i.e., HCl [ 16 ] against sulphuric acid [ 20 ], and varying extractant concentrations [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ].…”