Electrodeposition of nickel from sulfate solutions in the presence of aminoacetic acid

Article abstract of DOI:10.1134/S107042721001012X

Kinetics of nickel electrodeposition from sulfate electrolytes in the presence of aminoacetic acid at pH of 2.0 and 5.5 in the temperature range 20-50°C is considered. Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S107042721001012X

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 1, pp. 58−61. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © O.A. Taranina, N.V. Evreinova, I.A. Shoshina, V.N. Naraev, K.I. Tikhonov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83,
No. 1, pp. 60−63.
APPLIED ELECTROCHEMISTRY
AND CORROSION PROTECTION OF METALS
Electrodeposition of Nickel from Sulfate Solutions
in the Presence of Aminoacetic Acid
O. A. Taranina, N. V. Evreinova, I. A. Shoshina, V. N. Naraev, and K. I. Tikhonov
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received October 15, 2009
Abstract—Kinetics of nickel electrodeposition from sulfate electrolytes in the presence of aminoacetic acid at
pH of 2.0 and 5.5 in the temperature range 20–50°C is considered.
DOI: 10.1134/S107042721001012X
It is known [1] that various To obtain high-quality
coatingscomposedofiron-groupmetals, itisrecommended
to introduce aminoacetic acid into the electrolyte [1, 2],
mostly as a buffer additive [3]. It is known, however,
that glycine forms complexes of various compositions
with many metals [4]. Published data on the influence
of glycine on the kinetics of electrode reactions in
electrolyses of nickel salt solutions are scarce.
of N0 brand, as auxiliary electrodes; and saturated silver
chloride, as reference. The potentials were recalculated
to the standard hydrogen electrode scale. The buffer
capacity was determined by potentiometric titration,
following the procedure described in [6]. Electronic
absorption spectra of solutions were recorded with an
SF-56 spectrophotometer in the range 190–1100 nm in
quartz cuvettes with a layer thickness l = 1 cm.
The current efficiencies by nickel at various glycine
concentrations at 40°C are listed in Table 1 in relation to
the current density and solution pH. It can be seen that
the manner in which the CE varies with the aminoacetic
acid concentration depends on the pH value. For
example, at pH 5.5, introduction of 0.13 M of glycine
somewhat raises the CE, whereas further increase in
the glycine concentration hardly has any effect because
the CE fluctuates within 1–2%. However, the presence
of glycine results in that the outward appearance of the
coatings is improved, with the coatings becoming light
gray and lustrous, and the range of current densities at
which high-quality coatings are obtained is extended (to
10 A dm–2).
The goal of this study was to examine the kinetics of
electrode processes and coating deposition conditions in
an electrolysis of a nickel sulfate electrolyte containing
aminoacetic acid.
EXPERIMENTAL
The study was performed under the following
conditions: solution composition (M): NiSO4 0.36, NaCl
0.20, aminoacetic acid concentrations in the range 0.13–
0.30; pH 2.0 and 5.5; temperature range 20–50°C. The
.
solutions were prepared from NiSO4 7H2O and NaCl of
chemically pure grade and NH2CH2COOH of analytically
pure grade. The necessary pH value was set using
concentrated sulfuric acid or sodium hydroxide (both
of analytically pure grade). The concentration of nickel
ions in solution was determined by complexonometric
titration [5], and the current efficiency (CE) by nickel,
by the gravimetric method. Deposits were obtained in the
galvanostatic mode, using a B5-47 stabilized power source.
Polarization curves were measured potentiostatically in a
thermostated three-electrode glass cell. A 1-cm2 plate of
electrolytic nickel served as the working electrode; nickel
Another behavior is observed at pH 2.0: the CE sharply
decreases as the glycine concentration is raised. Probably,
presence of aminoacetic acid in the electrolyte makes
lower the hydrogen evolution overvoltage. It should be
noted, however, that, under the conditions studied, the
increase in the CE with the current density is preserved.
Similar dependences were observed at temperatures of 20
and 50°C. Metal deposits obtained from a solution with
pH 2.0 are light gray, matte, and show no cracking.
58

ELECTRODEPOSITION OF NICKEL FROM SULFATE SOLUTIONS
59
Table 1. Current efficiency by nickel at various glycine concentrations and pH values of the electrolyte
Table 2. Potential shift ΔE at various glycine concentrations
and current densities
The whole set of cathodic polarization curves and
values of the CE by nickel were used to calculate
partial curves of discharge of nickel ions. These results
are presented in Figs. 1a and 1b, whence follows that
an increase in the glycine concentration makes lower
the discharge rate of nickel ions. Plotted in the semilog
coordinates, the partial polarization curves (Fig. 2) have,
in a certain range of current densities, almost the same
slope ratio of 0.18 V for all of the electrolytes studied.
This fact indicates that the discharge rate of nickel ions
is limited by the same stage, presumably by the transfer
of a first electron. As the glycine concentration in the
solution increases, the potential is shifted in the negative
direction by the same value, irrespective of the solution
acidity (Table 2).
(a)
(b)
E, mV
E, mV
Fig. 1. Partial polarization curves of discharge of nickel ions at pH (a) 2.0 and (b) 5.5. (i) Current density and (E) potential; the same
for Figs. 2 and 4. Aminoacetic acid concentration (M): (1) 0, (2) 0.13, (3) 0.18, and (4) 0.3; the same for Fig. 4.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 1 2010

60
TARANINA et al.
E, mV
λ, nm
log i [A dm–2]
Fig. 3. Electronic absorption spectra of NiSO4 solutions at pH
(1, 2) 2.0 and (3, 4) 5.5. (D) Optical density and (λ) wavelength.
Aminoacetic acid concentration (M): (1) 0, (2, 4) 0.3, and (3)
0.13.
Fig. 2. Partial polarization curves of nickel deposition, plotted
in the Tafel coordinates, at pH (1, 3, 5) 2.0 and (2, 4, 6) 5.5.
Aminoacetic acid concentration (M): (1, 2) 0, (3, 4) 0.13, and
(5, 6) 0.3.
However, with the low affinity of nickel for oxygen-
containing ligands taken into account, formation of NiGly+
or NiCly2 is unlikely, which is indicated by the complete
coincidence of the electronic absorption spectra (Fig. 3,
curves 1 and 2).As the solution acidity decreases (pH 5.5)
and the amount of unprotonated glycine increases, the
intensity of the bands at 300 and 650 nm grows (Fig. 3,
curves 3 and 4), which confirms the formation of
a complex compound [9]. Thus, the too large values of
ΔE/Δlog i for the polarization curves, irrespective of the
solution acidity and glycine concentration, and the rise
in the overvoltage are possibly due to a simultaneous
adsorption of glycine on the electrode surface.
It can be suggested that the discharge of nickel ions is
hindered by nickel complexes of various compositions,
appearing in the solution. With the fact that, depending
on the glycine concentration, NiGly+ and NiGly2 species
(log β1 = 5.65, log β2 = 10.51 [7]) can be formed taken into
account, the shift of the potential from the equilibrium
value will be proportional to 2.3RTlog βi /nF [8] and
equal to –0.164 and –0.405 V, respectively. Therefore, it
seems reasonable to suggest that complexes of the type
NiGly+ can appear. However, electronic spectroscopy data
confirm the formation of complex species in the solution
bulk only for weakly acidic electrolytes (Fig. 3).At pH 2,
glycine is present in solution as a cation H3N+CH2COOH,
which can only be coordinated to nickel ions via oxygen.
The apparent activation energies of discharge of nickel
ions were calculated from the temperature dependence
(b)
(a)
E, mV
E, mV
Fig. 4. Anodic polarization curves of nickel at pH (a) 2.0 and (b) 5.5.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 1 2010

ELECTRODEPOSITION OF NICKEL FROM SULFATE SOLUTIONS
61
REFERENCES
of the cathodic process in the solutions under study. It was
found that, at pH 2.0 and aminoacetic acid concentrations
of 0.13 and 0.3 M, these energies are, respectively, 45.5 and
53.2 kJ mol–1, and for solutions with pH 5.5 at the same
concentrations of glycine, 31.4 and 34.0 kJ mol–1. These
values also confirm the slow course of the electrochemical
event complicated by the adsorption of glycine.
1. Voitsekhovskii, Yu.G., Voitsekhovskaya, R.N., and
Galyamova, T.A., Prikladnaya elektrokhimiya: Teoriya,
tekhnologiya i zashchitnye svoistva gal’vanicheskikh
pokrytii (Applied Electrochemistry: Theory, Technology,
and Protective Properties of Electroplated Coatings),
Kazan, 1989., pp. 8–16.
The presence of aminoacetic acid in the electrolyte also
affects the rate of the anodic process, with the nature of this
influence determined by the solution acidity. In electrolytes
with pH 2.0 (Fig. 4a), the dissolution rate decreases with
increasing glycine concentration and a passivity plateau is
observed at concentrations exceeding 0.18 M.According
to [10], the ionization of nickel at pH 2 occurs via formation
of a catalytic complex with sulfate ions. Probably being
adsorbed on the electrode surface, aminoacetic acid
displaces SO42– ions and thereby has an inhibiting effect.
In solutions with pH > 2, no passivity is observed (Fig.
4b); the process of nickel ionization is also retarded as the
glycine concentration in the electrolyte increases.
2. Vinogradov, S.N., Magomedova, E.A., Mal’tseva, G.N.,
and Makarycheva, I.V., Sbornik materialov Vserossiiskoi
nauchno-prakticheskoi konferentsii “Zashchitnye pokrytiya
v mashinostroenii i priborostroenii” (Proc.All-Russia Sci.-
Pract. Conf. Protective Coatings in Machine Building and
Instrument Making”), Penza, 2001., pp. 5–6.
3. Kurnakova, N.Yu. and Bakalai, V.I., Sbornik materialov
Vserossiiskoi nauchno-prakticheskoi konferentsii
“Zashchitnye pokrytiya v mashinostroenii i priborostroenii”
(Proc. All-Russia Sci.-Pract. Conf. Protective Coatings in
Machine Building and Instrument Making”), Penza, 2005,
pp. 22–25.
4. Dyatlova, N.M., Temkina, V.Ya., and Popov, K.I.,
Kompleksony i kompleksonaty metallov (Metal Complexons
and Complexonates), Moscow: Khimiya, 1988.
The buffer capacity of the electrolyte in the presence
of glycine exceeds that with boric acid. In addition,
the electrolytes studied can be used to obtain lustrous
coatings at current densities of up to 10 A dm–2 without
introduction of brightening additives.
5. Kruglova, E.G. and Vyacheslavov, P.M., Kontrol’
gal’vanicheskikh vann i pokrytii (Control over Galvanic
Baths and Electroplated Coatings), Leningrad: Mashgiz,
1961.
6. Peters., D.G., Hayes, J.M., and Hieftje, G.M., Chemical
Separations and Measurements: Theory and Practice of
Analytical Chemistry, Saunders Company, 1974.
CONCLUSIONS
(1) It was found that presence of glycine in a nickel
sulfate electrolyte makes lower the discharge rate of
nickel ions under any of the conditions studied.
7. Ohnaka, N. and Matsuda, H., J. Electroanalyt. Chem.,
1975, vol. 62., pp. 245–257.
8. Kravtsov, V.I., Ravnovesie i kinetika elektrodnykh reaktsii
kompleksnykh metallov (Equilibrium and Kinetics of
Electrode Reactions of Complex Metals), Leningrad:
Khimiya, 1985.
(2) Electronic spectroscopy data confirmed the
formation of nickel complexes with glycine in the solution
bulk only at pH 5.5 in the concentration range studied.
(3) An analysis of partial polarization curves
demonstrated that the discharge rate of nickel ions in
a glycine-containing sulfate electrolyte is limited by
the electrochemical stage of transfer of a first electron,
complicated by the adsorption of glycine.
9. Lever,A.B.P., Inorganic Electronic Spectroscopy, Elsevier
Science, 1985.
10. Ivanov, E.S., Ingibitory korrozii metallov v kislykh sredakh
(Inhibitors of Metal Corrosion in Acid Media), Moscow:
Metallurgiya, 1986.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 83 No. 1 2010