Zhaowu Zhu

Synergistic extraction of rare earth by mixtures of 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester and di-(2-ethylhexyl) phosphoric acid from sulfuric acid medium

Abstract The extraction of Nd 3+ and Sm 3+ , including the extraction and stripping capability as well as the separation effect of Nd 3+ or Sm 3+ , from a sulfuric acid medium, by mixtures of di-(2-ethylhexyl) phosphoric acid (HDEHP, H 2 A 2(0) ) and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (HEH/EHP, H 2 L 2(0) ) were studied. The distribution ratios and synergistic coefficients of Nd 3+ and Sm 3+ in different acidities were also determined. A synergistic extractive effect was found when HDEHP and HEH/EHP were used as mixed extractants for Sm 3+ or Nd 3+ . The chemical compositions of the extracted complex were determined as Nd · (HA 2 ) 2 · HL 2 and Sm · (HA 2 ) 2 · HL 2 . The extraction equilibrium constants, enthalpy change, and entropy change of the extraction reaction were also determined.

Synergistic extraction of cerium from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester and Di-(2-ethyl hexyl) phosphoric acid as extractant

Abstract Synergistic extraction of cerium(IV) from sulfuric acid medium using mixture of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester(HEH/EHP, HL) and Di-(2-ethyl hexyl) phosphoric acid (HDEHP, HA) as extractant was investigated. The results indicated that the maximum synergistic enhancement coefficients were obtained at the mole fraction of HEH/EHP=0.6, and cerium(IV) was extracted into organic phase in the form of Ce(SO 4 ) 0.5 HL 2 A 2 . A cation exchange mechanism was proposed for the synergistic extraction of Ce(IV). The equilibrium constants and thermodynamic functions such as Δ G , Δ H, and Δ S were determined in the extraction of Ce(IV) from sulfuric medium using mixture of HEH/EHP and HDEHP.

Synergistic extraction of rare earths by mixture of HDEHP and HEH/EHP in sulfuric acid medium

The extraction of RE(III) (RE=La, Nd, Sm, Gd) in sulfuric acid medium using the mixture of HDEHP(H2B2) and HEH/EHP(H2L2) was investigated. The synergistic enhancement coefficient(R) was calculated for La (1.96), Nd(3.52), Sm(5.96), and Gd(5.71), respectively, at pH=2.0, and it was seen that the R increased with the increase of aqueous quilibrium pH. The configuration of the extracted complexes was considered to be RE(SO4)xH2x(HB2)3 with HDEHP, RE(SO4)xH2x(HL2)3 with HEH/EHP, and RE(HB2)2(HL2) with their mixture as the extractant with the slope method. The equilibrium constants and stability constants were calculated. A cation exchange mechanism was proposed as well.