New Hydrophobic Eutectic Solvent Based on Bis(2,4,4-trimethylpentyl)phosphinic Acid and Menthol: Properties and Application

In this work, a new hydrophobic eutectic solvent (HES) based on bis(2,4,4-trimethylpentyl)phosphinic acid and menthol was synthesized and characterized for the first time. Important physical properties of the prepared HES, such as the density, viscosity, refractive index, as a function of temperature in the range 15–60 °C, were obtained. The new HES was applied for the extraction of Co, Ni, Cu, Mn, Al, and Fe from chloride solution. The extraction rate of Fe(III) reached 44%, while for other metals the extraction rate was not more than 3%. The potential possibility of the selective extraction of iron ions from an aqueous solution of a mixture of metals using the proposed HES was shown.