New Hydrophobic Deep Eutectic Solvent Based on Di-(2-Ethylhexyl)Phosphoric Acid and Trioctylphosphine Oxide: Properties and Application

Abstract

In this work, a new hydrophobic deep eutectic solvent (HDES) based on trioctylphosphine oxide and di-(2-ethylhexyl)phosphoric acid was obtained. The formation of HDES was confirmed by NMR and FT-IR spectroscopy. The physical properties of the synthesized HDES were studied, density, dynamic viscosity, refractive index in the range of 15–60 °C, and phase diagram. The possibility of extraction of Co(II) and Al(III) ions from nitrate aqueous solutions was studied. The regularities of the interfacial distribution of metal ions were studied depending on the time of the extraction process, the ratio of components in HDES and pH of the aqueous phase. It has been shown that this HDES can be used for the selective extraction of metal ions.

Keywords

• deep eutectic solvent
• di-(2-ethylhexyl)phosphoric acid
• trioctylphosphine oxide
• metal extraction
• liquid–liquid extraction