Abstract
The ionic liquid A327H+Cl− is generated by reaction of the tertiary amine A327 (industrial mixture of tri-octyl and tri-decyl amines) and hydrochloric acid solutions. In this study, the extraction of Au(III) by A327H+Cl− ionic liquid under various variables, including metal and ionic liquid concentrations, was investigated. Results indicate that A327H+AuCl4− is formed by an exothermic (ΔH° = −3 kJ/mol) reaction in the organic solution. Aqueous ionic strength influences the formation constant values, and the specific interaction theory (SIT) was used to estimate the interaction coefficient between AuCl4− and H+. Gold (III) was stripped using thiocyanate media, and from the strip solutions, gold was precipitated as gold nanoparticles.
Highlights
The concept of urban mining has widespread application because recycling is of primary importance, and modern life results in the generation of waste that contains a variety of valuable and non-valuable materials.Valuable items include electronic wastes, jewelry scraps, and similar products, which are of interest because they contain metals
It is claimed in the literature that organic diluents are not required when ionic liquids are used in the extraction of metal; the experience of the authors of this work showed that the use of an organic diluent was needed in this particular use of the ionic liquids, because: (i) The high viscosity of the ionic liquids impairs easy and quick phase separation; this viscosity results in a flowing problem in the process of scaling-up to mixer-settlers. (ii) The use of a diluent allowed the correct concentration of the ionic liquid to be used in each case
Preparation of A327H+ Cl− Ionic Liquid. This ionic liquid was+prepared by reaction of the tertiary amine A327 diluted in toluene
Summary
Valuable items include electronic wastes, jewelry scraps, and similar products, which are of interest because they contain metals. The separation and recovery of this precious metal, from any of the above materials, has attracted wide interest, and different separation technologies have been proposed for this task: adsorption [1,2], ion exchange [3], liquid membranes [4,5], and liquid–liquid extraction using ethers [6,7,8], amides [9], amines [10], ionic liquids [11] or phosphonic acid derivatives [12]. Liquid–liquid extraction or solvent extraction is one of these separation steps, and is currently used in the production of a series of metals, copper. The technology uses an organic extractant, normally diluted in a suitable diluent, which is characteristic to each case, to make the operation selective in relation to the targeted metal
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