Extraction of Cu(II), Ni(II), and Al(III) with the Deep Eutectic Solvent D2EHPA/Menthol

A new hydrophobic deep eutectic solvent (HDES) based on di(2-ethylhexyl)phosphoric acid and menthol has been proposed for the extraction of Al(III), Ni(II), and Cu(II) ions from aqueous solutions. The physicochemical properties of the synthesized deep eutectic solvent are determined as a function of temperature. The kinetics of the extraction of metal ions from hydrochloric acid solutions in an extraction system with an HDES has been studied. A comprehensive study of the extraction of metal ions with the proposed deep eutectic solvent was carried out under various conditions: the effect on the extraction of metal ions of the pH values of the aqueous phase, the ratio of the donor and acceptor of the hydrogen bond of the deep eutectic solvent, the volume ratio of the phases, and the concentration of chloride ions were described. It is shown that the proposed HDES can potentially be used to extract studied metal ions from aqueous solutions.