Sorption of Heavy Metals in Cationic and Anionic Forms
by SKS Synthetic Carbons Modified
with Nitrogen and Sulfur
S. S. Stavitskaya, V. M. Vikarchuk, S. V. Zhuravskii, N. N. Tsyba, and V. V. Strelko
Institute of Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received February 8, 2008
Abstract—Data on the sorbability of ions of heavy metals (lead, cobalt, cadmium, zinc, copper, nickel) from
Ringer's solution with complex composition by untreated SKS synthetic carbons and those modified with
nitrogen and sulfur were obtained. Exploratory studies of the sorption of complex anions of copper and iron
with complexing ligands (Cl and CN) were performed. Selectivity series of toxic metals were determined on
the basis of their calculated distribution coefficients. It was shown that the best sorption effect is due to the
presence of nitrogen atoms and strongly acidic SO
H groups in the carbon structure.
INORGANIC SYNTHESIS AND INDUSTRIAL
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 6, pp. 968–973. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © S.S. Stavitskaya, V.M. Vikarchuk, S.V. Zhuravskii, N.N. Tsyba, V.V. Strelko, 2009, published in Zhurnal Prikladnoi Khimii, 2009,
Vol. 82, No. 6, pp. 913–918.
The increasing role of adsorption in various
technological processes, including the adsorption of
heavy metals, favors continued search for carbon
materials with improved physicochemical properties
and performance characteristics.
Frequently, the sorption properties of carbons are
affected by the presence in their structure of atoms of
oxygen, hydrogen, nitrogen, sulfur, phosphorus, and
other elements because of their electronegativities
different from that of carbon. Of considerable interest
are, in particular, nitrogen-containing carbons that
have long been manufactured and studied [1–8].
Nitrogen atoms in a carbon structure behave as
polar centers: a nitrogen-containing carbon has a
higher surface polarity than a nitrogen-free carbon.
Nitrogen atoms raise the negative (pyridine nitrogen
[1, 7]) or positive (nitrogen atoms substituting carbon
atoms in the graphite lattice) charge on the carbon
surface. It is commonly believed [1, 3, 4, 8] that
nitrogen enhances the basicity of the carbon structure
and thereby enables its use in catalysis. It is known
that carbons containing chemically bound nitrogen
have an increased anion-exchange capacity that is one
of the most interesting properties of nitrogen-
containing carbons [1, 3–5, 8, 9].
For example, it can be seen from Fig. 1  that, in
contrast to the ordinary carbon sorbent composed of a
formaldehyde resin and having almost zero anion-
exchange capacity at pH ~6–8, a nitrogen-containing
carbon can absorb about 0.5 mg-equiv g
under these conditions. The increased anion-exchange
capacity of nitrogen-containing carbons opens up
prospects for their use in sorption of complex anions of
Fig. 1. Ion-exchange capacity A vs. the pH value of the
equilibrium solution for (1) nitrogen-containing activated
carbon SKN and (2) ordinary carbon prepared from phenol-
formaldehyde resin. (A) Adsorbed amount of Cl
4 8 12 pH