Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 2, pp. 186−191.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © T.Zh. Sadyrbaeva, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 2, pp. 202−208.
AND CORROSION PROTECTION OF METALS
Electrodialytic Separation of Cobalt(II) and Nickel(II)
Using Liquid Membranes Based on Tri-n-octylamine
and Trialkylbenzylammonium Chloride
T. Zh. Sadyrbaeva
Institute of Inorganic Chemistry, Riga Technical University, Salaspils, Latvia
Received September 10, 2012
Abstract—Electrodialytic separation of Co(II) and Ni(II) in the course of their transfer from 3–4 M HCl solutions
into dilute solutions of various acids using liquid membranes that contain anion-exchange carriers was studied.
The inﬂ uence exerted on the metal transport rate and separation efﬁ ciency by the compositions of the feed and
receiving aqueous solutions and of liquid membranes and by the electrodialysis current density was examined.
Under optimal conditions, in metal recovery from a solution containing an equimolar mixture of 0.01 M CoCl
, the separation factor β
is 147; when nickel in the feed solution is in excess, it reaches 330, and
when cobalt(II) is in excess, it exceeds 400.
Cobalt, nickel, and their compounds are widely
used in industry as components of alloyed steels and
magnetic alloys, as decorative and protective coatings
for metals, as catalysts in organic synthesis, as pigments
for ceramics and glasses, in production of batteries,
paints, and varnishes, and in medicine . Cobalt and
nickel often accompany each other in the nature and have
close physicochemical properties. Therefore, separation
of these elements is an important practical problem.
Separation of cobalt and nickel using anion-exchange
extractants is based on different stability of anionic
chloride complexes of these metals in HCl solutions.
Nickel(II) in hydrochloric acid solutions mainly forms
cationic aqua complexes, whereas cobalt(II) can form
anionic complexes in the presence of excess chloride
ions in solutions ; therefore, the metals can be
separated by anion-exchange extractions with salts of
amines and quaternary ammonium bases . Tertiary
amines are also used in membrane extraction as carriers
for cobalt(II) ions in its separation from nickel(II) using
impregnated [4, 5], emulsion [6–9], and polymeric 
membranes. Application of an electrostatic ﬁ eld to a
membrane system intensiﬁ es the transfer of ions through
liquid membranes and facilitates the back extraction
of metals from amine salt solutions . Previously
liquid membranes containing tri-n-octylamine (TOA)
and trialkylbenzylammonium chloride (TABAC) were
successfully used for separation of palladium from
macroimpurities of copper, nickel, and iron , of
platinum and iron , and of platinum and nickel
 in the course of recovery from hydrochloric acid
mixtures under the conditions of electrodialysis.
The goals of this work were to study the membrane
extraction of cobalt(II) from hydrochloric acid solutions