Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 4, pp. 569−573.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
L.Yu. Kotel, A.V. Brichka, S.Ya. Brichka, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 4, pp. 576−580.
OF SYSTEMS AND PROCESSES
Adsorption Properties of Modiﬁ ed Multilayer Carbon
Nanotubes with Respect to Benzoic Acid
L. Yu. Kotel, A. V. Brichka, and S. Ya. Brichka
Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received April 1, 2008
Abstract—Multilayer carbon nanotubes were modified by ultrasonic treatment in nitric acid and subsequent
calcination in an inert atmosphere of argon at temperatures of 500, 800, and 1200°C. The dependence of the
adsorption of benzoic acid on carbon nanotubes on the temperature of their calcination was analyzed.
The discovery of carbon nanotubes (CNT) by S. Iijima
in 1991 initiated a steadily increasing number of studies
in this area. Active development of methods for synthesis
of CNTs with prescribed properties and structure and
a search for their promising application areas were
commenced [1–3]. At present, CNTs are successfully used
as sorbents, which is due to their high speciﬁ c surface
area of up to 2000 m
Benzoic acid (C
COOH) belongs to permitted
synthetic preservatives most frequently used in Russia,
Ukraine, and other countries. The solubility of benzoic
acid is about 0.34 g per 100 g of water at 25°C. The
maximum permissible concentration of (C
for various food products is 150 to 2000 mg per gram
of a product . Together with parabens, salicylic acid,
and 4-hydroxy benzoic acid, benzoic acid is used in the
cosmetic industry and can penetrate into organisms from
various makeup preparations via respiratory tracts and skin
. Benzoic acid is a component of bottled sweet water
and juices, added to prolong their storage life. In natural
water basins, (C
COOH) is formed in the life activities
of various aquatic organisms and in their decomposition.
Industrial wastewater is a source of synthetic benzoic
acid found in surface water . Numerous human
diseases are caused by consumption of water containing
toxins, radionuclides, pathogenic microorganisms,
and substances whose content exceeds the maximum
permissible concentration. Some researchers believe that
COOH) is a carcinogen because, when reacting
with vitamin C, it forms benzene frequently found in tap
and bottled water. Benzene can cause malignant changes
in organs of a human organism. Therefore, there presently
exists the problem of a search for effective sorbents for
extraction of benzoic acid from water .
The adsorption activity of carbon nanotubes with
respect to polar organic molecules has been studied .
In [10, 11], experiments were performed on adsorption
of benzoic acid from aqueous solutions on activated
carbon. Single- and multilayer nanotubes have been used
for adsorption of zinc ions from aqueous solutions .
particles deposited onto the CNT surface have been
used to purify water to remove arsenates . In , the
advantage of carbon nanotubes over activated carbon as
sorbents for dioxins was demonstrated. The adsorption of
o- and p-xylene from water by carbon nanotubes oxidized
with nitric acid was studied in . The adsorption of
resorcin, phenol, catechine, hydroquinone, and pyrogallol
from water by oxidized multilayer was analyzed in 
in order to develop new adsorbents for water puriﬁ cation
to remove contaminants.
The aim of the present study was to examine the
adsorption of benzoic acid from water by modified
multilayer carbon nanotubes and to determine the
dependence of the adsorption of the acid by CNTs on the
temperature of their thermal treatment.
Certiﬁ ed multilayer carbon nanotubes (Nanothinx
S. A.; diameter 12–31 nm, length >10 μm, number of