Extraction and separation of Ce(iii) and Pr(iii) in the system containing two complexing agents with di-(2-ethylhexyl) phosphoric acid

Abstract

In order to develop a novel separation technology superior to the current extraction systems, the extraction behaviors of Ce(III) and Pr(III) from chloride medium with P204 in the presence of two complexing agents lactic acid (LA) and citric acid (H₃cit) have been reported. The distribution ratios increase with the increase of the equilibrium pH and the ratio of [H₃cit] : [LA] under certain conditions. The separation factors of Ce(III) and Pr(III) increase with the ratio of [H₃cit] : [LA] at fixed pH, and the maximum value is as high as 5.78 in this complexing system. The maximum saturated extraction capacity is 27.08 g L⁻¹ which is close to that in the current saponified P507 extraction system. The equilibrium constants and thermodynamic functions, ΔG, ΔH and ΔS have been calculated. Lactic acid and citric acid can be effectively recycled and enriched, providing possibilities for dissolving minerals in the circular process. By comparison with the experimental results, this complexing extraction method could be regarded as an effective strategy for separating REs.