ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 10, pp. 1571!1575. + Pleiades Publishing, Inc., 2006.
Original Russian Text + E.S. Plokhov, M.G. Mikhalenko, S.V. Plokhov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 10,
AND ION-EXCHANGE PROCESSES
Ion-Exchange Recovery of Nickel(II) from Wash Water Formed
in Electroless Plating in Acid Hypophosphite Solutions
E. S. Plokhov, M. G. Mikhalenko, and S. V. Plokhov
Nizhni Novgorod State Technical University, Nizhni Novgorod, Russia
Received May 26, 2005; in final form, March 2006
Abstract-Kinetic aspects of extraction of Ni(II) ions with KU-2-8 cation-exchange resin in the Na
from wash water produced in electroless nickel-plating were studied. The optimal conditions and parameters
of ion-exchange purification and regeneration of the cation-exchanger were determined.
Despite the undeniable advantages of Ni3P coat-
ings , a wider industrial application of process-
es for their deposition from acid hypophosphite solu-
tions is hindered by the formation of large amounts of
liquid nickel-containing waste , mostly constituted
by spent plating solutions and wash water. The amount
of this waste can be reduced to a minimum by inte-
grated solution of the following problems: use of ef-
fective stabilizers in solutions for electroless nickel-
plating, optimization of the plating and electrolyte
adjustment conditions and of the composition of
the adjusting solution used in plating, development
of technologies for recovery and utilization of com-
ponents from spent solutions and wash water .
The best technical and economic effect is achieved
by purification of wash water to remove nickel(II)
ions. It is known that joint use of ion exchange and
electrolysis, with preliminary sorption treatment of
wash water with activated carbon, is advisable for re-
covery of heavy metals ions from wash water .
The aim of this study was to determine the funda-
mental kinetic aspects and the optimal conditions and
parameters of ion-exchange recovery of Ni(II) from
wash water after electroless nickel-plating in acid
As objects of study served model solutions and
industrial wash water of the following composition
O 0.331.25 (in terms of nickel
ions), sodium hypophosphite (NaH
) 2.0, sodium
) 0.4, sodium acetate 2.2, and
COOH 3. The pH value was 4.5. The electrolyte
temperature was 20 + 2oC. The concentrations of im-
purity metal ions [Cu(II), Zn(II), Fe(III), and Sn(II)]
in wash water were very low because of the short time
of use of electroless nickel-plating solutions, which
did not allow their quantitative determination. Re-
moval of these ions was not considered in this study
and they were not introduced into model solutions,
because they had virtually no effect on the results
of ion-exchange recovery of nickel(II). No stabilizer
(thiourea, 0.0005 g l
) was introduced, either, into
model solutions, because wash water is subjected to
sorption treatment before ion exchange and this com-
pletely extracts the stabilizing agent from it.
The ion-exchange recovery of Ni(II) from wash
water was studied on a laboratory setup comprising
a glass column with an inner diameter of 0.019 m.
The ratio of the inner diameter of the column to
the height of a bed of the swollen ion exchanger was
1 : 9. The mass of the KU-2-8 cation exchanger in
form in the column was 21.89 g. The concen-
tration of nickel cations in wash water and in eluates
was determined by spectrophotocolorimetry 
and atomic-absorption spectroscopy  on SF-26
and SF-115 Saturn spectrophotometers, respectively.
The relative determination error did not exceed +2%.
Wash water produced in electroless nickel-plating
in acid hypophosphite solutions contains nickel(II)
in several cationic forms. Together with simple hy-
aqua-complex ions, [Ni(H
(n =13 6)
are present in the wash water, the most stable of which
is the complex ion with octahedral structure .
The ion-exchange purification was performed to
remove all kinds of nickel ions without separation.
For this purpose, the cation exchanger was used in