Normalized polarity indices of tri-n‑butyl phosphate metal complexes in ionic liquid using Reichardt’s dye as polarity probe

Abstract

• Detail solvatochromic studies in ionic liquid medium. • Polarity of ionic liquid phase containing extractant. • Polarity of metal-ligand complex in ionic liquid. • Application towards understanding the third phase formation during the extraction of metal ions. Exploring the polarity of ionic liquid phase composed of a ligand bonded to metal complex is essential for understanding the insights of solvent extraction. The normalized polarity of the ionic liquid phase composed of the tri- n ‑butyl phosphate ligand and metal-ligand complex (metal = U , Nd, Th) was determined by a spectrophotometric technique using Reichardt’s dye as the polarity probe. The polarity was measured as a function of various parameters such as concentration of ionic liquid, concentration of nitric acid, ligand concentration and metal ion concentration of the system. The polarity increased with increase in the concentration of ionic liquid, nitric acid and metal ion in ionic liquid phase. The results are reported in this paper.