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MODIFICATION OF FUNCTIONAL GROUPS IN NANOTUBE
SYNTHESIS
Mamatqodirov B.D.
Yakubov Y. Y.
Ibragimov A.B.
Sidorenko A.Yu.
Institute of General and Inorganic Chemistry, Academy of Sciences of
Uzbekistan, 77a Mirzo Ulugbek Street, Tashkent 100170, Uzbekistan.
Institute of Chemistry of New Materials of the National Academy of Sciences of
Belarus.
Our address: 220084, Minsk, Belarus. E-mail:
mamatqodirovbehzodjon@gmail.com
https://doi.org/10.5281/zenodo.15797126
Over the past decade, kaolin-based nanotubes have once again become the
focus of numerous studies and patents, even though their nanoscale structure
was identified several decades ago [1]. This renewed interest is associated with
the rapid development of nanoparticles and nanotechnology over the last
twenty years, which has led to growing attention to naturally occurring
nanostructures [2]. Kaolin nanotubes possess several advantages over synthetic
nanotubes such as carbon nanotubes [3]. Although the purification of kaolin may
increase the cost of secondary raw materials, kaolin remains a low-cost material
with a global supply exceeding several thousand tons annually [4].
Figure 1. Description of Functional Group Transformations
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Accordingly, aluminosilicate nanotubes were successfully synthesized from
kaolin through a multistep chemical treatment process (Figure 1). The
morphological characteristics of the resulting nanostructures were investigated
using scanning electron microscopy (SEM), which revealed that the synthesized
nanotubes possessed lengths ranging from 800 to 1100 nm and outer diameters
between 50 and 60 nm, confirming the formation of well-defined tubular
aluminosilicate structures. The FTIR spectrum of the pristine kaolinite displayed
prominent absorption bands in the 1000–1200 cm⁻¹ range, which are assigned
to the stretching vibrations of Si–O bonds, with specific peaks observed at 909,
995, 1023, and 1113 cm⁻¹. The spectral region between 400 and 600 cm⁻¹
corresponds to the deformation vibrations of Si–O bonds, where significant
absorption bands at 453 and 530 cm⁻¹ were attributed to Si–O–Al and Si–O–Si
linkages, respectively. Additionally, a distinct absorption band at 952 cm⁻¹
indicates the presence of Al–OH vibrational modes. In the high-frequency region
(3700–3500 cm⁻¹), strong absorption bands at 3619 and 3696 cm⁻¹ are
observed, corresponding to the stretching vibrations of structural –OH groups
that participate in hydrogen bonding with tetrahedral (Si–O) layers. A broad
absorption feature near 3500 cm⁻¹ further confirms the presence of physisorbed
water molecules on the kaolin surface. Upon chemical modification of the clay,
notable changes were detected in the FTIR spectrum. New absorption bands
appeared at 3530, 3621, and 3693 cm⁻¹, while the intensity of the 3696 cm⁻¹
band markedly decreased. These spectral changes are indicative of the
formation of hydrogen bonds between surface-bound Al–OH groups and S=O
functionalities, reflecting molecular-level interactions within the kaolinite
layered structure. Moreover, the emergence of absorption bands at 2851 and
2924 cm⁻¹ corresponds to the stretching vibrations of –CH₃ groups, confirming
the adsorption of organic reagents on the clay matrix. Following extraction, the
absorption bands at 3530 and 3693 cm⁻¹—characteristic of dimethyl sulfoxide
(DMSO)—disappeared, and the remaining bands at 3619 and 3621 cm⁻¹
exhibited reduced intensity. This attenuation is associated with the formation of
Al–O–Me (metal-alkoxide) linkages. The slight shift of the 3619 cm⁻¹ peak to
3621 cm⁻¹ further supports the presence of hydrogen bonding interactions
between methanol molecules and Al–OH groups.
Subsequent thermal treatment of the organically modified kaolin did not
result in substantial alterations in the FTIR spectral profile, suggesting that the
structural and chemical modifications introduced during synthesis were stable
under thermal conditions. Collectively, these spectroscopic findings confirm the
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successful functionalization and transformation of kaolin into aluminosilicate
nanotubes, as evidenced by characteristic FTIR features consistent with their
expected chemical structure.
References:
1. A. Streubel , J. Siepmann , R. Bodmeier Int. J. Pharm. , 241 ( 2002 y. ) , b. 279
2.Daoyong Tan a b,Peng Yuan a,Faiza Annabi Bergaya c, Huaguang Yu d, Dong
Liua, Xongmey Liu a b,Hongping He a,(2013) b.4
3. B. Munos , A. Ramila , J. Peres-Pariente , I. Dias , M. Vallet-Regi. Mater15
( 2003 yil ) , b. 500
4. P.Xorkajada , A.Ramila , F.Jerard , M.Vallet - Regi , 8 ( 2006 ) , bet. 1243
