ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 4, pp. 672!674. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.G. Kasikov, A.M. Petrova, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 4, pp. 689 ! 690.
Effect of the Structure of Octanols on Their
Extraction Capacity for Rhenium(VII)
in 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 October 16, 2006
Abstract-Extraction of Re(VII) from sulfuric acid solutions with isomers of octanol was studied.
In their physicochemical characteristics, aliphatic
meet the basic requirements to in-
dustrial extractants. Furthermore, with these alcohols,
there is no need to use some diluents and modifiers,
which simplifies extraction systems. That is why in-
tensive research is being conducted on extraction of
inorganic acids and some chemical elements with
alcohols, primarily with various isomers of octanol
Despite that octanols differ in their physicochem-
ical characteristics, in most of these studies no com-
parison has been made of the extraction capacity of
the isomers. At the same time, Karamushko et al.
 demonstrated that alcohols can differ significantly
in their extraction capacity for Nb(V), depending on
their structure, and they recommended 2-octanol for
extraction processing of fluorometallate solutions.
The goal of this study was to examine the effect of
the structure of octanols on their extraction capacity
and to search for efficient extractants for Re(VII).
For this purpose, we studied the extraction of Re(VII)
from sulfuric acid solutions with isomers of octanol.
The possibility of use of octanols for extraction of Re
has been reported previously . However, in these
studies, the results were obtained under different ex-
perimental conditions and, generally, without control
over the equilibrium concentration of sulfuric acid.
In the experiments on extraction of Re(VII), we
used 1-octanol and DL-2-octanol from Vekton Private
Company, and 3-octanol (synthetic grade, Merck). To
prepare the initial solutions, we used chemically pure
. The extraction experi-
ments were carried out at room temperature in 50-ml
volumetric cylinders for 5 min at 1 : 1 organic to aque-
ous phase ratio. Rhenium in the raffinates was deter-
mined spectrophotometrically from the band of the
thiourea complex of Re(IV), which is formed in
the presence of Sn(II) as a reducing agent. The meas-
urements were performed at l = 390 nm on a KFK-3
photoelectric colorimeter . The sulfuric acid con-
centration in the aqueous phase was determined by
titration. The Re(VII) concentration in the organic
phase was estimated as the difference between its con-
centrations in the initial solution and raffinate, with
account taken of changing phase volumes.
The dependence of the Re(VII) distribution ratio
on the H
concentration in the initial solution
is shown in Fig. 1 for three octanol isomers. With
increasing acid concentration, D
passes through a maximum at 437MH
ing on the isomer, and then decreases. The increase
in the extraction capacity of the alcohols with the acid
concentration is due to the fact that hydrogen ions are
involved in the extraction by the hydration-solvation
+(n + 1)H
The subsequent decrease in the distribution coeffi-
cients can be attributed to a concurrent extraction of