ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 2, pp. 185!188. C Pleiades Publishing, Ltd., 2007.
Original Russian Text C D.E. Chirkst, T.E. Litvinova, V.S. Starshinova, G.S. Roshchin, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80,
No. 2, pp. 187!190.
AND INDUSTRIAL INORGANIC CHEMISTRY
Cerium(III) Extraction with Oleic Acid
from Nitrate Solutions
D. E. Chirkst, T. E. Litvinova, V. S. Starshinova, and G. S. Roshchin
St. Petersburg Mining Institute, St. Petersburg, Russia
Received October 10, 2005; in final form, October 2006
Abstract-Cerium(III) extraction with oleic acid in o-xylene from nitrate solutions was studied.
The extraction mechanism and the dependence of the distribution ratio on pH and composition of the organic
and aqueous phases were examined. The thermodynamic characteristics of extraction were calculated.
The best studied among extractants used for re-
covery of REEs from nitrate solutions are organophos-
phorus compounds, mainly tributyl phosphate. How-
ever, with sulfuric  and hydrochloric [23 4] acids
are more effective in leaching of lean ores and tech-
nologically produced raw materials and TBP is inef-
ficient with these media .
REEs are present in acid solutions in the form of
anionic complexes [M(An)
3 3 zx
, where An is anion,
and x is the anionic charge equal to 1 or 2 . There-
fore, REEs are commonly recovered from acid solu-
tions with anion-exchange extractants, mainly with
carboxylic acids .
In this study, the characteristics of cerium(III) ex-
traction with oleic acid from nitrate solutions were
determined and compared with those of tributyl phos-
phate and trialkylbenzylammonium nitrate.
In our experiments, cerium(III) was extracted from
aqueous nitrate solutions of Ce(III) with a concentra-
tion of 0.01 mol kg
, which is close to the REEs
concentration in process solutions formed in extractive
recovery of REE from depleted and technogenic raw
materials. An 0.5 M solution of oleic acid in o-xylene
was used as extractant. The dissociation constant of
oleic acid is 1.25 0 10
. The required pH was
adjusted by adding sodium hydroxide or nitric acid.
The REE concentration in the initial and equilib-
rium solutions was determined photometrically with
Arsenazo III .
The cerium(III) concentration in the organic phase
was determined from the difference between its con-
centrations in the initial solution and equilibrium aque-
ous phase with account of the difference between the
volumes (weights) of the organic and aqueous phases
are the equilibrium concentrations
) of metals in the organic and aqueous
phases, respectively; c
, REE concentration in the ini-
tial aqueous solution (mol kg
ratio of the aqueous and organic phases equal to 50 : 5;
and the organic phase density r
= 0.86+ 0.1 g cm
The distribution ratio was calculated by the equation
D = c
The data on cerium(III) extraction with 0.5 M
oleic acid in o-xylene from nitrate solutions within
the pH range 333.5 are listed in Table 1.
Table 1. Distribution ratios of Ce(III) D
at various pH
(initial Ce(III) concentration 0.014 mol kg
³ mol kg
3.0 ³ 13.1 ³ 0.9 ³ 0.65
3.5 ³ 9.6 ³ 4.4 ³ 4.52
4.0 ³ 8.9 ³ 5.1 ³ 5.81
4.4 ³ 6.4 ³ 7.6 ³ 11.78
4.5 ³ 4.7 ³ 9.3 ³ 19.70
4.8 ³ 1.7 ³ 12.3 ³ 71.67
5.0 ³ 1.3 ³ 12.7 ³ 98.89
5.5 ³ 0.6 ³ 13.4 ³ 235.00