Extraction of Rhodium(III) with Petroleum Sulfoxides
from Hydrochloric Acid Solutions
N. G. Afzaletdinova and Yu. I. Murinov
Institute of Organic Chemistry, Ufa Branch, Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Received December 21, 2009
Abstract—Extraction of rhodium(III) from hydrochloric acid solutions with petroleum sulfoxides was studied.
The optimal conditions of its recovery were found. The composition and structure of the compound being
extracted was determined by electronic absorption,
H NMR, and IR spectroscopies and elemental analysis.
OF SYSTEMS AND PROCESSES
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 9, pp. 1570–1575. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © N.G. Afzaletdinova, Yu.I. Murinov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 9, pp. 1471–1475.
Recently, the increasing amount of mining of leaner
ores with a more complex composition has aroused
considerable interest in petroleum sulfoxides (PSOs) as
extractive agents for rare and radioactive elements
[1–5]. The assortment of industrial extractive agents is
insufficient for performing hydrometallurgical techno-
logical processes. These are for the most part include
tributyl phosphate, di(2-ethylhexyl)phosphoric acid,
carboxylic acids, and amines.
Petroleum sulfoxides, mostly composed of cyclic
structures, markedly exceed in extraction capacity
dialkyl sulfoxides and tributyl phosphate and are close
in this regard to phosphonates [6, 7].
It should be noted hardly any reports on studies of
the extraction of rhodium(III) with sulfoxides of
petroleum origin can be found in the literature.
Our study is concerned with the extraction me-
chanism of rhodium(III) from hydrochloric acid
solutions with sulfoxides of petroleum origin.
We produced petroleum sulfoxides having the form
of a brown liquid from a concentrate of sulfides from
the kerosene–gas oil fraction of Arlan oil (boiling
away at 270–360°C) by the method described in .
The content of the sulfoxide sulfur in the PSOs was
11.7 wt % at a total sulfur content of 12.1 wt %. The
purity of the petroleum sulfoxides was judged from IR
spectra and elemental analysis data. The content of the
sulfoxide sulfur was determined by titration of a
weighed portion of a sample with a solution of per-
chloric acid in dioxane on a pH-340 potentiometer .
Petroleum sulfoxides are thermally stable under
heating to 100°C for up to 12 h. It has been found that,
in oxidation of petroleum sulfides to sulfoxides, the
structure of molecules being oxidized remains
unchanged (Table 1). As a diluent in our study of the
extraction properties of PSOs served para-xylene (bp
138°C) in a mixture with 15% decanol.
We used the K
O)] salt synthesized by
the method described in . Working solutions of
potassium aquapentachlororhodate were prepared by
dilution of the starting solution of the rhodium(III) salt
with a 6 M solution of HCl. Rhodium(III) was deter-
mined spectrophotometrically with tin chloride .
The extraction was performed from freshly prepared
solutions of rhodium(III) .
The extraction was performed at room temperature
and organic to aqueous phase ratio of 1 : 1. The phases
were agitated with an R-3 magnetic rabble (Radelkis).
The phase separation after the agitation was clearly
pronounced and occurred in 1–2 min after the
termination of the contact.
Electronic absorption spectra (EASs) were recorded
with a Specord M-40 spectrophotometer in glass and
quartz cuvettes, and IR spectra, with an IR Prestige-21
spectrophotometer (Fourier Spectrophotometer, Shimadzu)
in the range 4000–400 cm
in Vaseline oil. The
spectra were recorded using disks made of poly-