ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 12, pp. 2028!2030. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + L.D. Kurbatova, D.I. Kurbatov, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 12, pp. 1950!1952.
AND INDUSTRIAL INORGANIC CHEMISTRY
Extractable Oxo Complexes of Vanadium(V)
with Di(2-ethylhexyl) Hydrogen Phosphate
L. D. Kurbatova and D. I. Kurbatov
Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Yekaterinburg, Russia
Received January 31, 2007
Abstract-Extraction of vanadium(V) with di(2-ethylhexyl) hydrogen phosphate from 1.038.0 M aqueous
sulfuric acid solutions was studied. The optimal conditions for the extraction were found. The composition
of the extractable complex was determined, and the reaction equation for the extraction of V(V) was es-
tablished. The extraction constant was determined.
It is known that di(2-ethylhexyl) hydrogen phos-
phate (HDEHP) is an efficient extractant for V(IV). It
has also been reported  that HDEHP poorly extracts
V(V) present in solutions in the form of dioxocations
. At the same time, it was shown earlier that
HDEHP effectively extracts V(V) from weakly acidic
solutions. In this study, we examined extraction of
V(V) with HDEHP from moderately concentrated aqu-
eous sulfuric acid.
Before use, di(2-ethylhexyl) hydrogen phosphate
was purified to remove mono(2-ethylhexyl) dihy-
drogen phosphate . The extraction of V(V) with
HDEHP was studied at 25.0 + 0.5oC by multistage
contact of neat HDEHP with a solution of V(V) in
aqueous sulfuric acid for 4 min. The V(V)-containing
solutions were prepared by dissolving potassium
metavanadate in aqueous sulfuric acid (chemically
pure grade). The V(V) concentration was determined
by the atomic-absorption method. The electronic ab-
sorption spectra of both the solutions of V(V) in
aqueous sulfuric acid and V(V)3HDEHP extracts were
recorded in the range 13 000330 000 cm
in a 1-cm
quartz cell (Specord UV-VIS spectrophotometer).
The IR spectra of V(V)3HDEHP extracts (thin layer
between KRS-6 plates) were recorded in the range
on a Specord 75 IR spectrometer.
In this study we examined the extraction of V(V)
from both straight moderately concentrated aqueous
sulfuric acid solutions (c
= 1.038.0 M) and those
containing cationic and anionic additives. We found
that the extraction of V(V) with HDEHP starts at
a sulfuric acid concentration higher than 5.0 M, when
extractable ionic species of V(V) are formed. The elec-
tronic absorption spectra of a solution of V(V) in
aqueous sulfuric acid of concentration 1.0 33.0 M con-
tains the absorption bands at 48000, 44000, and
, which belong to mononuclear complexes
of V(V) with the dioxocationic VO
center . An increase in the sulfuric acid concentra-
tion over 5 M results in that the optical density grows
and the shape of the spectrum noticeably changes.
These spectroscopic effects suggest that a new kind
of extractable ionic V(V) species is formed under
To identify ionic species of V(V) extracted with
HDEHP, the IR and electronic absorption spectra
of V(V)3HDEHP extracts were examined. It can be
seen from Fig. 1 that, in going from HDEHP3H
Fig. 1. IR spectra of HDEHP3H
V(V) extracts. ( T) Transmission and (n) wavenumber.
(1) HDEHP3V(V) extract (c
= 0.1053 M), (2) HDEHP-
V(V) extract after compensation of HDEHP absorption,
extract, and (4) HDEHP.