ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 7, pp. 1058!1062. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.A. Blokhin, N.D. Abovskii, Yu.V. Murashkin, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 7, pp. 1089!
AND ION-EXCHANGE PROCESSES
Ion-Exchange Recovery of Palladium(II) from Multicomponent
A. A. Blokhin, N. D. Abovskii, and Yu. V. Murashkin
St. Petersburg State Institute of Technology (Technical University), St. Petersburg, Russia
Received March 16, 2007
Abstract-Ion-exchange sorption of palladium(II) from both concentrated aqueous hydrochloric acid solution
containing Fe(III), Sn(II), Zn(II), and Cu(II) and weakly acidic concentrated aqueous ammonium chloride
solution containing Zn(II) and Cu(II) was studied. The Purolite S920, Purolite S924, and Purolite S984 macro-
porous resins with the thiourea, thiol, and polyethylenepolyamine functional groups, respectively, were used as
sorbents. Strongly basic Purolite A500 anion exchanger was also tested. The desorption of palladium(II) with
aqueous ammonia, hydrochloric acid, and acidified aqueous thiourea was examined.
In refining platinum metals (PMs), large volumes
of spent PM-containing solutions are formed. The
palladium(II) content in them can be as large as
150 mg l
. The platinum metals are commonly re-
covered from spent refining solutions by precipitation
in the form of poorly soluble compounds and also by
cementation or electrolysis . However, these meth-
ods do not ensure the required completeness of PM
recovery. Furthermore, their use leads to the formation
of poorly soluble products depleted of PMs, whose
further processing to recover PMs is difficult.
Extensive published data on ion-exchange sorption
of PMs show that resins with the thiourea, thiol, and
polyethylenepolyamine functional groups selectively
sorb these metals . Therefore, we can expect that
application of these resins will allow more complete
recovery of PMs from spent refining solutions. How-
ever, currently ion-exchange sorption is rather seldom
used for this purpose. The ion-exchange methods are
mainly used for preconcentrating PMs before their
chemical analysis . Studies concerning industrial
processing of PM-containing solutions mainly dealt
with commercial resins nonselective to PMs .
The modern chemical industry produces a large
number of resins with various selective functional
groups, which allows selection of sorbents suitable
for more complete recovery of PMs from spent multi-
component refining solutions.
In this study we examined the possibility of more
complete selective ion-exchange recovery of palladi-
um(II) from two kinds of spent refining solutions:
after precipitation of ammonium hexachloroplati-
nate(IV) and trans-dichlorodiamminepalladium(II).
We tested the following commercial macroporous
complexing resins produced by Purolite Int. Ltd.
company: Purolite S920, Purolite S924, and Purolite
984 with the thiourea, thiol, and polyethylenepoly-
amine functional groups, respectively. For compari-
son, Purolite A500 strongly basic anion exchanger
was also tested.
In the static sorption experiments, weighed por-
tions of a resin were brought in contact with solutions
containing a constant amount of macrocomponents
and impurity metals and variable amount of palladi-
um(II) at 1 : 200 ratio of the dry resin (g) and liquid
(ml). On attainment of the sorption equilibrium (53
7 days), the solution was separated from the resin and
analyzed for palladium. The amount of palladium
sorbed on the resin was determined by the difference
between its concentrations in the initial and equilibri-
um solutions, taking into account the weighed portion
of the resin, its specific volume, and the solution
volume. In determining the degree of palladium de-
sorption from the resin, its weighed sample pre-
liminarily saturated with palladium(II) was washed
with 0.3 M aqueous hydrochloric acid and then
brought in contact with a desorbing solution.