Dissolution of metal oxides in task-specific ionic liquid

Richter, Janine; Ruck, Michael

doi:10.1039/c9ra06423k

Cited by 45 publications

(80 citation statements)

References 30 publications

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“…For all copper atoms, almost equal distances to coordinating betaine oxygen atoms are found [193.6(2)–197.1(2) pm]. These values are in the same range as in previously reported monomeric and dimeric copper betaine complexes [33,35] . For chloride, shorter distances to copper are present in equatorial positions (226.5–231.3 pm) and longer distances in axial positions (243.4–246.4 pm).…”

Section: Resultssupporting

confidence: 83%

“…Furthermore, ν as (COO) is not or very weakly observed at 1770 cm −1 as expected for uncoordinated [Hbet] + . Instead, bands shifted to lower wave numbers occur, suggesting the coordination of betaine [35] . These observations suggest a precipitated copper‐betaine coordination compound free of [NTf 2 ] − anions for the acetone and acetonitrile precipitations, but [NTf 2 ] − ‐containing or ‐associated copper‐betaine complexes for the precipitations in the other solvents.…”

Section: Resultsmentioning

confidence: 86%

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Speciation of Copper(II)‐Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids

2020

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The application of ionic liquids for the dissolution of metal oxides is a promising field for the development of more energy‐ and resource‐efficient metallurgical processes. Using such solutions for the production of valuable chemicals or electrochemical metal deposition requires a detailed understanding of the chemical system and the factors influencing it. In the present work, several compounds are reported that crystallize after the dissolution of copper(II) oxide in the ionic liquid [Hbet][NTf2]. Dependent on the initial amount of chloride, the reaction temperature and the purity of the reagent, copper crystallizes in complexes with varying coordination geometries and ligands. Subsequently, the influence of these different complex species on electrochemical properties is shown. For the first time, copper is deposited from the ionic liquid [Hbet][NTf2], giving promising opportunities for more resource‐efficient copper plating. The copper coatings were analyzed by SEM and EDX measurements. Furthermore, a mechanism for the decomposition of [Hbet][NTf2] in the presence of chloride is suggested and supported by experimental evidence.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 86%

Speciation of Copper(II)‐Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids

2020

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“…Indeed, a positive effect of water on the dissolution was confirmed, but by the addition of [Hbet]Cl, thus providing chloride as additional, nucleophilic ligand in the IL [Hbet] 2 [NTf 2 ]Cl, significantly more metal oxides can be dissolved in the IL, including quite unreactive metal oxides, such as Fe 2 O 3 (haematite), MnO 2 (pyrolusite) and ThO 2 . However, under the chosen conditions, chloride ions cause a partly decomposition of the IL [106]. Similar to the previously discussed separation experiments, the optimisation of the reaction parameters, such as reaction temperature and duration, as well as chloride concentration could enable the avoidance of this effect.…”

Section: Task-specific Ilsmentioning

confidence: 69%

“…As the dissolution of metal oxides in [Hbet][NTf 2 ] comes down to an acid-base reaction, we consider especially the basicity of the metal oxide to be significant. Hence, for example, a very good solubility is found for alkaline earth metal oxides [106]. However, because of the lack of quantitative data about the basicity of different metal oxides, a validation of this assumption and the exact prediction of dissolution behaviour is not possible, yet.…”

Section: Task-specific Ilsmentioning

confidence: 99%

Synthesis and Dissolution of Metal Oxides in Ionic Liquids and Deep Eutectic Solvents

Richter

Ruck

2019

Molecules

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Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion.

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“…The idea that ILs could replace typical industrial solvents which are generally considered toxic, volatile and flammable, has aroused great interest in the field of metallurgy. There is a significant group of ILs that are partially or conditionally immiscible with water and have been examined in many studies as media for metal extraction, either in metal oxides dissolution, or in liquid/liquid separation processes [ 3 , 4 ]. An important issue in such process is controlling the mutual solubility of IL-H 2 O systems.…”

Section: Introductionmentioning

confidence: 99%

Utilizing Recyclable Task-Specific Ionic Liquid for Selective Leaching and Refining of Scandium from Bauxite Residue

2021

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Ionic liquids (ILs) have attracted great interest in the field of extractive metallurgy mainly because they can be utilized in low temperature leaching processes where they exhibit selectivity and recyclability. A major drawback in mixed aqueous-IL systems, is IL dissolution in the aqueous phase, which leads to IL losses, increasing the overall processing cost. This study advances the method for recovering scandium (Sc) from bauxite residue (BR) using as leaching agent the IL betainium bistriflimide, [Hbet][Tf2N] mixed with water, which has been reported in previous publications. Ionic liquid leachate (IL-PLS) was prepared by leaching BR with a mixture of [Hbet][Tf2N]-H2O and subjected to different stripping experiments using hydrochloric acid. The advancement, presented in this work, is related with the optimization of the metal extraction (stripping) from the IL-PLS, where an aqueous solution with high Sc concentration and minimum metal impurities and minimum IL co-extraction is produced. It is further proven that the metal cation extraction is defined by the stoichiometry of the acidic solution and the dissolution (losses) of the IL in the aqueous phase can be minimized by adjusting the volume ratio and the acid concentration. A two-step stripping process described, achieves the selective increase of Sc concentration by 8 times in the aqueous solution, while maintaining cumulative IL losses to similar levels as the optimum 1 step non-Sc selective stripping process.

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Dissolution of metal oxides in task-specific ionic liquid

Abstract: Investigation on the dissolution of 30 metal oxides in the water-free ionic liquid [Hbet][NTf2] and the catalytic effect of chloride for the application in green ore processing.

Cited by 45 publications

References 30 publications

Speciation of Copper(II)‐Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids

Speciation of Copper(II)‐Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids

Synthesis and Dissolution of Metal Oxides in Ionic Liquids and Deep Eutectic Solvents

Utilizing Recyclable Task-Specific Ionic Liquid for Selective Leaching and Refining of Scandium from Bauxite Residue

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