Aliquat 336 in Solvent Extraction Chemistry of Metallic ReO₄⁻ Anions

Abstract

A study of the liquid–liquid extraction of ReO4− anions from hydrochloric acid solutions using the ionic liquid Aliquat 336 (QCl: trialkyl(C8–C10)methylammonium chloride) via the well-known method of slope analysis along with the determination of the process parameters is presented. This study employs CCl4, CHCl3 and C6H12 as diluents. This study was carried out at room temperature (22 ± 2) °C and an aqueous/organic volumetric ratio of unity. The ligand effect on the complexation properties of ReO4− is quantitatively assessed in different organic media. The organic extract in chloroform media is examined through 1H, 13C and 15N NMR analysis as well as the HRMS technique and UV-Vis spectroscopy in order to view the anion exchange and ligand coordination in the organic phase solution. Final conclusions are given highlighting the role of the molecular diluent in complexation processes and selectivity involving ionic liquid ligands and various metal s-, p-, d- and f-cations. ReO4− ions have shown one of the best solvent extraction behaviors compared to other ions. For instance, the Aliquat 336 derivative bearing Cl− functions shows strongly enhanced extraction as well as pronounced separation abilities towards ReO4−.

Keywords

• liquid–liquid extraction
• Aliquat 336
• ReO₄⁻
• organic diluents
• selectivity