ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 7, pp. 1157–1161. © Pleiades Publishing, Ltd., 2011.
PHYSICAL CHEMISTRY
OF SOLUTIONS
LiquidꢀLiquid Solvent Extraction of Rare Earths from Chloride
Medium with SecꢀNonylphenoxy Acetic Acid and Its Mixtures
1
with Neutral Organophosphorus Extractants
Pengfei Xiao, Changli Bao, Naizhong Song, Cui Li, and Qiong Jia
College of Chemistry, Jilin University, Changchun 130022, China
eꢀmail: jiaqiong@jlu.edu.cn
Received December 30, 2009
Abstract—In the present study, secꢀnonylphenoxy acetic acid (CA100) and its mixtures with four neutral
organophosphorus extractants, triꢀbutylꢀphosphate (TBP), 2ꢀethylhexyl phosphonic acid diꢀ2ꢀethyl ester
(DEHEHP), Cyanex923, and Cyanex925 have been applied to the extraction of rare earths. Results show that
all the four mixing systems do not have evident synergistic effects on the extraction of rare earths. The differꢀ
ent extraction effects have been considered to the separation of rare earths. The four mixtures may be applied
to the separation of yttrium from some certain lanthanoids at proper mole fractions of CA100.
DOI: 10.1134/S0036023611070321
1
1
. INTRODUCTION
stants, and thermodynamic functions have also been
determined.
As a kind of organic carboxylic acid, naphthenic
In our previous work, the synergistic extraction of
REs with mixtures containing CA100 or another carꢀ
boxylic acid, secꢀoctylphenoxy acetic acid (CA12),
has been reported [6–8, 11, 12, 21]. The mixing sysꢀ
tems of CA100 or CA12 with di(2ꢀethylhexyl) phosꢀ
phoric acid (D2EHPA), 2ꢀethylhexyl phosphonic acid
monoꢀ(2ꢀethylhexyl) ester (HEHEHP), bis(2,4,4ꢀtriꢀ
methylpentyl) dithiophosphinic acid (Cyanex301)
acid has been widely used for the separation of rare
earths. Although carboxylic acid is easy to get and
cheap, it has some shortcomings such as complicated
composition, instability in technology, easy to emulsiꢀ
fication, etc. Secꢀnonylphenoxy acetic acid (CA100),
an extractant recently developed by Shanghai Institute
of Organic Chemistry, Chinese Academy of Sciences,
has several advantages including stable composition, have been applied to the extraction of REs. All the
low solubility, easy preparation, and uneasy emulsifiꢀ above organophosphorus extractants are acidic
cation during extraction [1]. The extraction of rare reagents. However, there are no reports about the
earths (REs) with CA100 has been reported in some extraction of REs with the mixing systems containing
previous papers [2–5], Wang et al. [3] have studied the these two carboxylic acids and neutral organophosꢀ
3+
extraction behavior of Eu from hydrochloric acid phorus extractants.
2
+
2+
2+
2+
2+
solutions together with Zn , Cd , Co , Ni , Cu ,
In the present study, CA100 and its mixtures with
four neutral extractants, triꢀbutylꢀphosphate (TBP),
2ꢀethylhexyl phosphonic acid diꢀ2ꢀethyl ester
2+
2+
3+
Mn , and Mg . It is proved that Eu can be effecꢀ
tively separated from the other metal ions.
(
DEHEHP), Cyanex923, and Cyanex925, have been
Synergistic extraction, i.e. the extraction with two
kinds of extractants, has been applied extensively in
order to enhance extractability and selectivity. Kinds
of mixing systems have been employed to the synergisꢀ
tic extraction of REs. Organophosphorus acids [6–
used for the extraction of REs. The extraction effects are
determined and considered for the separation of REs.
2. EXPERIMENTAL
1
6], neutral organophosphorus reagents [14–20],
amines [13, 15], and ꢀdiketones [18–21] are very
common extractants used in synergistic extraction sysꢀ
tems. For example, Sun et al. [10] have investigated Pr O (99.95%), Eu O (99.99%), Tb O (99.999%),
2.1. Reagents
β
Highꢀpurity La O (99.999%), Ce O (99.99%),
2
3
2
3
2
3
2
3
2
3
the synergistic extraction of REs using mixtures of Ho O (99.999%), Tm O (99.999%), Lu O (99.995%),
2
3
2
3
2
3
CA100 and bis(2,4,4ꢀtrimethylpentyl)phosphinic acid
Y O (99.99%) were obtained from Changchun Instiꢀ
2 3
in n
ꢀheptane. A cation exchange mechanism has been tute of Applied Chemistry, Chinese Academy of Sciꢀ
proposed. The equilibrium constants, formation conꢀ ences (Changchun, China), Stock solutions of REs
were prepared by dissolving their oxides in concenꢀ
1
The article is published in the original.
trated hydrochloric acid and diluting to the required
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