Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 1, pp. 40−43.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © Z.V. Podol’skaya, M.V. Buzaeva, E.S. Klimov, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 1, pp. 39−43.
INORGANIC SYNTHESIS AND INDUSTRIAL
Adsorption of Heavy Metal Ions on Galvanic Sludges
and Disposal of the Sludges in Soil
Z. V. Podol’skaya, M. V. Buzaeva, and E. S. Klimov
Ul’yanovsk State Technical University, Ul’yanovsk, Russia
Received April 5, 2010
Abstract—The sorption capacity of ferritized galvanic sludge toward nickel(II), zinc(II), and copper(II) ions was
studied. Sorption isotherms were plotted, and quantitative characteristics of adsorption were determined. Ferritized
sludges are stable in the natural environment and thus can be disposed of in soil in an environmentally friendly way.
The principal challenge to application of modern
process systems is the development of environmentally
sound technologies whose cycle is maximally closed,
and waste production, minimized .
One of the pressing environmental problems faced
by machine-building enterprises whose production
cycle includes electroplating procedures is that of
integrated wastewater treatment to remove toxic heavy
metal ions. To this end, natural and synthetic sorbents
are promising. Recent studies have shown that, in
wastewater treatment applications, expensive synthetic
sorbents can be replaced by cheaper natural materials or
process waste .
Here, we studied the sorption properties of ferritized
galvanic sludges and explore the possibilities for
environmentally safe disposal of these sludges in the
natural soil environment.
Sorption properties of the ferritized galvanic sludge
(FGS) were determined by static and dynamic methods.
Zinc, nickel, and copper salt solutions containing the
respective cation in a ﬁ xed concentration were mixed
with the calculated weighed portion of FGS (a 1–2-mm
fraction) at the solid : liquid ratio of 1 : 50. The mixture
was stirred for 90 min, after which the sorbent was
ﬁ ltered off, and the residual concentration of the cations
was determined in the ﬁ ltrate.
To assess the dynamic sorption capacity of the FGS,
the solution containing the respective metal cation in the
concentration of 100 mg l
was passed through a col-
umn packed with FGS (bed height 100 mm) at a rate
2 ml min
A ﬁ eld experiment on disposal of the initial and fer-
ritized galvanic sludges in soil was carried out in the
2007–2009 period according to GOST (State Standard)
17.4.4.02–91. Simultaneously, the background concen-
trations of the metals in natural soil were monitored. The
humus content in soil horizons down to 150 cm was 6.8–
0.9%. The soil acidity was close to neutral, pH 6.9–7.2.
The content of heavy metal ions was determined on
an S-115-M1 atomic-absorption spectrophotometer by
the standard technique. The results of the analyses were
processed using Microsoft Excel program .
One of the new approaches to sludge treatment
consists in chemical stabilization (ferritization) via
formation on the metal hydroxide surface of a strongly
adhered layer of mixed metal–iron oxides, ferrites.
Galvanic sludge is ferritized in an alkaline medium (pH
9–11) containing Fe(II) ions at 60°C under oxidation
of the reaction mixture with atmospheric oxygen .
The entire process can be represented schematically as