Influence of Synergistic Tributyl Phosphate and Di-(2-ethylhexyl)phosphoric Acid for Separation of Gadolinium and Samarium by Emulsion Liquid Membrane

Abstract

Gadolinium is one of the rare earth elements, which plays an essential role in modern industry. Its separation from mixtures of other rare earth elements is challenging due to similar physical and chemical properties. The extraction method using an emulsion liquid membrane is an effective and simple method for separating low concentration gadolinium from other rare earth elements mixtures. It is more eco-friendly than the liquid-liquid extraction process and also has various advantages. This study aims to determine the effectiveness, permeability and optimum formulation conditions for the separation of gadolinium and samarium using synergistic ligands tributyl phosphate and di-(2-ethylhexyl)phosphoric acid. The results showed a quantitative extraction (87.40%) of gadolinium ion at the optimum conditions of 0.025 M tributyl phosphate + 0.075 M di-(2-ethylhexyl phosphate), 4% span 80 as surfactant, 9000 rpm emulsification stirring speed and 0.5 M nitric acid as stripping phase, for a feed containing 1.5 mg/L gadolinium ion and 3 mg/L samarium ion at 5 M HNO3.