Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 5, pp. 801−805.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
A.V. Mamchenko, I.M. Kosygina, O.A. Savchenko, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 5, pp. 751−754.
OF SYSTEMS AND PROCESSES
Dynamics of the Na
on a Carboxy Cation Exchanger
A. V. Mamchenko, I. M. Kosygina, and O. A. Savchenko
Dumanskii Institute of Colloid Chemistry and Water Chemistry,
National Academy of Sciences of Ukraine, Kiev, Ukraine
Received July 15, 2009
Abstract—Nonequilibrium dynamics of the Na
exchange in water softening on a Lewatit CNP 80 carboxylic
cation-exchanger was studied at a widely varying linear velocity of water ﬁ ltration. The kinetic coefﬁ cient of the
pore-diffusion mass-transfer was determined at various ﬂ ow rates of the model solution.
It is known that ion-exchange processes are perform-
ed in ﬁ lters with a dense bed of an ion-exchange resin.
The technological cycle is closed and includes the
following procedures: water treatment, loosening of the
ion-exchanger bed, regeneration of the ion exchanger,
and washing of the ion-exchanger bed to remove the
excess reagent and salts of desorbed ions.
exchange occurs in water softening
on ﬁ rst-stage cation-exchanger ﬁ lters. An a priori
calculation of technological characteristics of ion-
exchanger ﬁ lters can be made in terms of the theory of
the nonequilibrium sorption dynamics [1–5]. Analytical
solutions to a system of equations have been obtained
for particular cases, in which the sorption kinetics is
limited only by the outer- or inner-sphere diffusion and
a parallel transfer of the sorption front occurs in the
ion-exchanger bed. These solutions make it possible
to prognosticate working parameters of ion-exchanger
ﬁ lters [4–10], i.e., to determine how their operation
mode depends on the length of the ion-exchanger bed,
ﬁ ltration rate of the ﬂ uid ﬂ ow, and sorption equilibrium
conditions (type of the sorption isotherm), which is the
main requirement to be satisﬁ ed when optimizing the
equipment operation .
The theory of the nonequilibrium sorption dynamics
has been tested in calculations of the sorption of
chlorides by weakly basic polyacrylic anion exchangers
[12, 13] and in the stage of regeneration of polyacrylic
cation exchangers .
The goal of our study was to examine the non-
equilibrium dynamics of the Na
exchange and to
analyze the possibility of using the theory for calculating
Because carboxylic cation exchangers have high
total exchange capacity and their cost is approximately
three times that of sulfocation exchangers synthesized
from copolymers of styrene and divinylbenzene, the
height of the acrylic ion-exchanger bed should be as
small as possible. Manufacturers of carboxy acrylic
cation exchangers specify the conditions guaranteeing
their effective operation: the minimum bed height of
the carboxylic cation exchanger of no less than 0.8 m
and the ﬂ ow rate of water being treated of up to 40 m
. When carboxylic acrylic cation exchangers are
used in domestic water-treatment installations, the bed
height of the ion exchanger is, as a rule, 1.0–1.2 m. With
these circumstances taken into account, the experiments
were performed at a bed height of Lewatit CNP 80
cation exchanger of 0.8 m (the bed heights are given as
recalculated to the H-form of the ion exchanger). The
ion exchanger preliminarily converted to the Na
was charged into a glass column.
We prepared a model solution from commercial