1070-4272/04/7707-1097C2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 7, 2004, pp. 1097!1099. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 7,
2004, pp. 1112!1115.
Original Russian Text Copyright + 2004 by Nagornyi, Kolyshkin, Vol’khin.
AND ION-EXCHANGE PROCESSES
Mercury(II) Sorption on Nickel(II) Hydroxide:
Influence of Halide Ion Concentration and pH of the Solutions
O. V. Nagornyi, A. S. Kolyshkin, and V. V. Vol’khin
Perm State Technical University, Perm, Russia
Received November 25, 2003
Abstract-Sorption of Hg(II) on b-Ni(OH)
was studied as influenced by chloride ion concentration and pH
of the solutions, affecting the Hg(II) speciation. The sorption mechanism was considered.
Mercury(II) compounds are biologically hazardous.
Mercury and its compounds are concentrated naturally
by soil particles and mineral suspension and are ac-
cumulated in bottom sediments. Accumulation and
transfer of mercury in the nature is largely controlled
by adsorption .
Sorption is used to remove mercury compounds
from aqueous solutions. Leikin et al.  used organic
anion-exchangers as sorbents for negatively charged
mercury halide complexes. Sorption of mercury(II) on
natural minerals, kaolinite , goethite , and quartz
, was studied.
Although many minerals can adsorb mercury com-
pounds, only synthetic inorganic sorbents are effi-
ciently used at present to remove mercury compounds
from aqueous solutions. More than 90% of Hg(II) is
removed with freshly prepared hydrated iron(III)
oxide from aqueous solutions with pH from 5 to 8.6
. A number of new inorganic sorbents including
those for anionic complexes have been developed to
date . Nickel(II) hydroxide  and double nickel
hydroxides with other metals  have relatively high
anion-exchange capacity for Hg(II) complexes. There-
fore, the study of synthetic inorganic sorbents for
Hg(II) is an urgent problem.
The diversity of mercury species present in aque-
ous solutions complicates selection of inorganic
sorbents for Hg(II). For example, in aqueous solutions
anions, Hg(II) exists in the form of
the following aqua, hydroxoaqua, and mixed hy-
droxoaquachloride or chloride complexes: Hg
[1, 4, 10, 11]. Formation
of cationic, neutral, and anionic mercury(II) species
can result in incomplete mercury sorption from aque-
ous solutions. Neutral and anionic Hg(II) species are
stable mainly at pH close to that of natural waters .
In this case, anion exchangers can be used as the
sorbents. However, to determine the mechanism of
Hg(II) sorption on metal hydroxides exhibiting anion-
exchange properties, additional studies are required.
The aim of this work was to determine the influ-
ence of Cl
concentration and pH of the solution on
Hg(II) sorption on nickel(II) hydroxide and to propose
the sorption mechanism.
Nickel(II) hydroxide exists in a- and b-modifica-
tions. In this work we studied b-Ni(OH)
modifications have the layered brucite structure. The
interlayer spacings in b-Ni(OH)
lattice are broadened
owing to incorporation of H
O molecules (c =
0.80 nm); the brucite layers in b-Ni(OH)
closer (c = 0.46 nm) . The a-modification is un-
stable and is unsuitable as a sorbent.
was prepared by exchange reaction of
aqueous solution of Ni(NO
with NaOH taken in
a 5% excess. The resulting precipitate was washed
with distilled water and granulated by freezing. To
impurity, the granulated material was
treated with 0.1 M NaOH for a long time. The NO
content in the solid phase was determined by IR spec-
The sorption experiments under dynamic conditions
were performed by the conventional methods .
Aqueous Hg(II) solutions were prepared from
O. Mercury halide complexes were syn-
thesized by addition of aqueous solutions of KCl,
KBr, and KI. All the salts were of analytically pure
grade. The Hg(II) content in the solution was deter-
mined by absorption of the mercury complex with
Crystalline Violet at l = 605 nm using a KFK-2MP
The relative content of different Hg(II) species
formed at various concentrations of free Cl