Liquid-liquid extraction of barium with DEPHA: chemical equilibrium

Abstract

The objective of this work was to evaluate a liquid - liquid extraction process to separate barium in aqueous phase by means of an organic phase consisting of DEPHA (bis-2-ethylhexyl phosphate) in kerosene and isopropyl alcohol as modifying agent. Different variables were studied: a) metal concentration in the liquid phase, b) pH of the solution, c) concentration of the organic carrier and d) ratio of the organic to aqueous phase volume. A recovery efficiency of 89.5% was obtained using an organic solution based on DEPHA, 30% (V/V) and isopropyl alcohol, 30% (V/V) as selective extraction medium. The extraction of barium occurs at pH 11. A solution containing 100 mg/L of BaCl2.2H2O was used as aqueous phase. The chemical equilibrium present in the system was described and the parameter KqE = 0.338 was obtained. This parameter is useful for establishing the viability of the industrial barium separation process in the aqueous phase.

Keywords

• barium
• heavy metals
• liquid–liquid extraction
• DEPHA