Redox Reactions and Metal Speciation in Ionic Liquids, Brines and Leachates: Electrochemical and Spectroscopic Investigations of Metallurgical Reactions

Datum

07.03.2018

Zeit

10:00 - 11:00

Sprecher

Prof. Gero Frisch

Zugehörigkeit

TU Bergakademie Freiberg, Institut für Anorganische Chemie

Sprache

en

Hauptthema

Chemie

Andere Themen

Physik

Host

Prof. Vinzenz Brendler

Beschreibung

Redox and complexation reactions are part of many metallurgical processing chains. Redox potentials of metals are strongly influenced by the coordination of the solution species, which is controlled through the composition of the solvent. Ionic liquids and brines provide a high level of control over metal speciation through judicious choice of potential ligands in the solvent [1]. However, actual design is only possible if the link between solvent composition, metal speciation and redox behaviour is thoroughly understood. We investigate metal complexation with spectroscopic methods such as EXAFS or Raman spectroscopy and try to connect speciation to electrochemical behaviour of metals in ionic liquids with various anions [2,3]. These results are compared to aqueous solutions containing a range of concentrations of the same complexant, illustrating the high level of reactivity control in ionic liquids. Fig.1 shows a simple example from the redox chemistry of copper, where the stability window of the monovalent oxidation state is controlled by chloride activity. Using examples from chemically very different metals, we compare the electrochemical series with its ionic liquids equivalents. We are currently transferring electrochemical methods to determine equilibrium constants [4] from aqueous systems to ionic liquids, with the aim to model solution speciation ionic media. Results can be applied to metal plating and mineral processing [5-7]. In aqueous solutions, modelling of leaching solutions and mechanistic studies into leaching and bioleaching reactions for sulfidic ores have been performed. Our data show e.g. that copper can play an important role in the iron-mediated sulfide oxidation chain (Fig.2), which is also part of microbial leaching mechanisms. In abiotic leaching, we aim to design new mineral processing techniques using other redox shuttles such as iodine/iodide (Fig.3).

Letztmalig verändert: 07.03.2018, 08:50:53