ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 377!379. + Pleiades Publishing, Inc., 2006.
Original Russian Text + O.M. Trokhimenko, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3, pp. 383!386.
AND ION-EXCHANGE PROCESSES
Sorption of Molybdoarsenates Reduced by Ascorbic Acid
with Polyurethane Foams Based on Ethers, Esters,
and Their Copolymers
O. M. Trokhimenko
Shevchenko Kiev National University, Kiev, Ukraine
Received June 20, 2004; in final form, June 2005
Abstract-Sorption of molybdoarsenates reduced by ascorbic acid from aqueous solutions with polyurethane
foams based on ethers, esters, and their copolymers was studied in relation to the phase weight ratio and
Preconcentration is required to determine the total
content of arsenic or the content of its separate species
in the environment by physicochemical methods at
concentrations close to the maximum permissible
concentration (MPC) .
At present, the most widespread extraction methods
give way to sorption methods, which provide higher
distribution coefficients of microcomponents without
using toxic organic solvents .
Arsenic(V) as molybdoarsenate is recovered on
activated carbon  or on membrane nitrocellulose
filters in the presence of quaternary ammonium bases
. It was shown in  that molybdoarsenate is effi-
ciently recovered on an Amberlyte XAD-8 polyacry-
late sorbent, or on thin-layer cellulose triacetate filters
in the presence of tri-n-octylamine. Since polyure-
thane foams contain ether and amino groups [5, 6],
i.e., functional groups of organic solvents recovering
heteropoly complexes, they sorb such complexes with
phosphorus, silicon [7, 8], and arsenic  as central
There is substantial difference between solvents
and sorbents from the practical viewpoint: solvents are
individual chemical substances, whereas sorbents are
materials. The sorption properties of materials can
somewhat vary depending on producer or even from
one batch to another . Therefore, the analytical
characteristics should be studied for the same batch.
In addition, materials based on organic polymers can
undergo aging under the action of light, moisture, and
air depending on storage conditions.
In this study, we examined sorption of molybdoar-
senate reduced with ascorbic acid (RMA) on poly-
urethane foams based on ethers (PUF-1), esters
(PUF-3), and their copolymers (PUF-2). We cannot
guarantee the complete repeatability of the results
because of the reasons mentioned above. However,
general features of the behavior of these sorbents with
respect to RMA can be revealed.
The stock solution of sodium hydroarsenate
[chemically pure grade, 100 mg As(V) in 1 cm
prepared by dissolving an accurately weighed portion
of the compound. The other solutions were prepared
by dilution of the stock solution. The RMA solutions
were prepared in the presence of excess molybde-
num(VI) and ascorbic acid  taking into account
that preliminarily synthesized and isolated heteropoly
complexes, when dissolved in water, undergo irrevers-
ible acid3base transformations with formation of prod-
ucts with central atom : ligand ratio equal to 1 : 12,
1 : 11, 1 : 9, etc.
Acetone (chemically pure grade) was used to
desorb complexes from the PUF surface.
Polyurethane foams based on ethers, esters, and
their copolymers of 5-30, 35-98 and ER trademark,
respectively, produced by Radikal plant (Kiev) were
cut into 3 0 3 0 3 mm cubes and washed with sulfuric
acid, water, and acetone before use .
Electronic absorption and diffuse reflection spectra
were recorded on a Specord M-40 spectrophotometer
Sorption was measured in the static mode. A PUF
sample [(0.0503 0.500)+ 0.001 g] was introduced into
a beaker with an RMA solution (253500 cm
). A PUF
cube was pressed to a glass bottom with a spatula to