1070-4272/04/7702-0249 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 2, 2004, pp. 249!253. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 2, 2004,
Original Russian Text Copyright + 2004 by Shunkevich, Martsinkevich, Medyak, Sokol, Filanchuk, Soldatov.
OF CHEMISTRY AND TECHNOLOGY
Comparison of Fibrous Carboxylic Ion Exchangers
in Water Treatment to Remove Heavy Metal Ions
A. A. Shunkevich, R. V. Martsinkevich, G. V. Medyak, V. P. Sokol,
L. P. Filanchuk, and V. S. Soldatov
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received March 4, 2003
Abstract-Treatment of drinking water to remove heavy metal ions Pb
with commercial fibrous carboxylic ion exchangers FIBAN Kh-1, K-3, K-4, and K-5 was studied.
Features of metal ion sorption from two-component solutions were determined. A comparative evaluation
of the sorption selectivity of FIBAN fibrous ion exchangers with respect to heavy metal ions was made.
Fibrous carboxylic ion exchangers are of interest
in treatment of natural water and wastewater to re-
move heavy metal ions . However, methods usu-
ally used in studying metal sorption with both fibrous
and granulated ion exchangers do not allow assess-
ment of their practical efficiency in water purification.
These methods give too optimistic estimations and
reveal no significant differences between various car-
boxylic ion exchangers. The capacity with respect
to an ion being recovered, which is the criterion of
the sorptive power, is determined by a static method
at a preset volume ratio of the sorbent to the solution
containing a metal in a too high concentration [5, 6].
The model solution containing 135gl
ions is prepared with distilled water with addition of
0.5 M supporting ions, usually Na
. Carboxylic ion
exchangers are very weakly selective with respect to
these ions as compared to double-charged ions. Thus,
the data obtained are related to the systems far from
the real water for which the sorbents are intended.
In such experiments, the amount of sorbed ions is
actually determined by the total ion-exchange capacity
and pH of the initial and equilibrium solutions.
In natural water, the concentration of heavy metal
ions is usually substantially lower than that used in the
model solution, and the content of these ions should
be monitored at the maximum permissible concentra-
tion (MPC) limit. As a rule, water to be purified con-
tains a background of metal ions (Na
) with the concentrations exceeding the con-
centration of toxic ions by 235 orders of magnitude.
The problem of water treatment to remove iron is
solved separately, and then water containing Na
, and Mg
is usually subjected to purification.
Water with moderate hardness contains 1.533mM
) ions, which are also selectively sorbed
by carboxylic ion exchangers and compete with heavy
metal ions for ion-exchange centers. In the static
method of sorption, pH and concentrations of support-
ing and target ions change simultaneously in the equi-
librium solutions, and hence each point of the sorption
curve is related to different conditions. Therefore, the
static method of determination of the ion exchanger
sorption power in a multicomponent solution inade-
quately characterizes the sorbent behavior in purifica-
tion of real drinking water.
In this study, real possibilities of commercial
FIBAN carboxylic ion exchangers in treatment of
drinking water to remove heavy metal ions Pb
, and Zn
were assessed under
the dynamic conditions.
FIBAN Kh-1, K-4, and K-3 ion exchangers pro-
duced by the Institute of Physical Organic Chemistry
and FIBAN K-5 ion exchanger produced by Ekofil-
Deko Research and Production Association in the form
of a staple with single fibers about 30 mm in diameter
and 66 mm long were used in the experiments. FIBAN
Kh-1, K-3, and K-5 ion exchangers are products of
chemical modification of Nitron polyacrylonitrile
(PAN) fiber. They contain several kinds of carboxy
groups and a certain amount of various basic groups.