Extraction of Li(I), Al(III), and Fe(III) from Hydrochloric Solutions with Hydrophobic Eutectic Solvent TIBPS/Menthol

A new hydrophobic eutectic solvent based on triisobutylphosphine sulfide (TIBPS) and menthol is proposed, its main physicochemical properties are studied, and its extraction capacity for Fe(III), Al(III), and Li(I) ions is assessed. For the TIBPS/menthol system, a solid–liquid phase diagram is constructed and the interaction between the components in the eutectic solvent is established using IR and NMR spectroscopy. The temperature dependences of the dynamic viscosity, density, and refractive index of the proposed eutectic solvent are established. The extraction of Fe(III), Al(III), and Li(I) ions from hydrochloric acid solutions using TIBPS/menthol is studied depending on the concentration of HCl and NaCl, the volume ratio of the phases, and the initial concentration of the metal. The temperature dependences of the degree of extraction of metal ions are obtained and an assessment of the thermodynamic parameters of extraction is carried out. The indices of re-extraction of Fe(III) ions from the organic phase with distilled water are determined and the degree of its extraction with repeated use of the eutectic solvent is established. The potential of using the proposed hydrophobic eutectic solvent for the extraction of metals from aqueous solutions is shown.