ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 6, pp. 914!919. + Pleiades Publishing, Inc., 2006.
Original Russian Text + A.G. Kasikov, A.M. Petrova, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 6, pp. 925!929.
AND INDUSTRIAL INORGANIC CHEMISTRY
Recovery of Rhenium(VII) with Triisooctylamine
from Sulfuric Acid Solutions
A. G. Kasikov and A. M. Petrova
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Resources,
Kola Scientific Center, Russian Academy of Sciences, Apatity, Murmansk oblast, Russia
Received March 23, 2006
Abstract-Extraction recovery of rhenium(VII) with triisooctylamine from model sulfuric acid solutions was
studied. The effect of the composition of the organic and aqueous phases on the recovery of rhenium(VII) was
analyzed, and the composition of rhenium(VII) complexes in the organic phase was determined. The possibil-
ity of effective re-extraction of rhenium(VII) from triisooctylamine with ammonia solutions was demonstrated.
Rhenium is one of the most needed rare elements;
the demand for rhenium has markedly increased re-
cently because of its larger-scale consumption in
manufacture of refractory alloys [1, 2]. The main
sources of rhenium are solutions of washing sulfuric
acid, in which rhenium concentrated is in catching of
roaster gases formed in pyrometallurgical processing
of molybdenum, copper, and copper-nickel ores .
The method of liquid extraction is widely used in
practice for recovery of rhenium(VII) from industrial
washing sulfuric acid solutions, with mixtures con-
taining trialkylamine used as extracting agents in
most cases . The extraction of rhenium(VII)
with tertiary amines of normal structure was also
studied in .
Data on application of tertiary amines of branched
structure, which are industrial extracting agents ,
for recovery of rhenium(VII) are exceedingly scarce
In view of the fact that the extracting capacity of
branched amines may markedly differ from that of
similar compounds of normal structure  and
sulfuric acid solutions are frequently used in practice,
the present study was aimed to examine the extraction
of rhenium(VII) from H
solutions with mixtures
As extracting agent served solutions containing
5330 vol % industrial triisooctylamine (TIOA) of
Hostarex A 324 brand (no less than 95% main sub-
stance and up to 5% primary and secondary amines)
in a Escaid 100 diluent with addition of 20370 vol %
isomeric aliphatic alcohols (1-octanol or 2-ethyl-hex-
anol-1 of pure grade).
The extracting agent was preliminarily converted
into the salt form via contact with a H
of the same concentration as a solution of rhenium,
from which the extraction was performed.
Model rhenium-containing solutions were prepared
by dissolution of ammonium perrhenate in distilled
water, with addition of a necessary amount of chem-
ically pure sulfuric acid. The concentration of rheni-
um(VII) was varied from 0.001 to 0.036 M, and that
of sulfuric acid, from 0.1 to 9 M.
The extraction was performed in separatory funnels
at a volume ratio of the organic to aqueous phase
equal to 1 : 25 at room temperature in the course of
5 min, which provided that equilibrium was attained
by the system.
The content of rhenium(VII) in the aqueous phase
was determined spectrophotometrically from the colora-
tion intensity of the thiourea complex of rhenium(IV),
formed in the presence of Sn(II) as reducing agent.
The light absorption was measured with a KFK-3
photoelectric colorimeter at a wavelength l = 390 nm
 or by the atomic-emission method on a Plazma
400 spectrometer. The content of rhenium in the or-
ganic phase was calculated as the difference of its con-
tents in the aqueous phase before and after extraction.