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INFRARED SPECTRAL ANALYSIS OF THE IONITE BASED ON
DIMETHYLOLCARBAMIDE AND ORTHOPHOSPHORIC ACID AND ITS
COMPLEX WITH MERCURY (II) ION
Toirova Gulshoda
Doctoral student of Inorganic Chemistry, Termez State University
https://orcid.org/0009-0005-6412-3389
Alikulova Iroda
4th year student at Termez State University
Abduganiyeva Dilafruz
4th year student at Termez State University
abduganiyevadilafruz88@mail.com
Abstract:
This study investigates the infrared (IR) spectra of an ionite synthesized from
dimethylolcarbamide and orthophosphoric acid and its complex formed with mercury (II)
ion. The presence of functional groups in the ionite and spectral changes after the
formation of the complex were analyzed. Based on the results obtained, conclusions were
drawn about the ionite’s selectivity toward metal ions and the complexation mechanism.
Introduction:
Ion exchange materials are of great importance in modern analytical chemistry, industrial
technologies, and environmental protection. They are widely used in processes such as
ion separation, purification, and selective sorption from solutions. The ion exchange
capacity of ionites depends on their internal structure and active functional groups, which
makes them sensitive and selectively interactive with heavy metals, radioactive elements,
and other harmful pollutants. Ionites synthesized from dimethylolcarbamide and
orthophosphoric acid possess a combination of multiple functional groups (amine,
carbonyl, phosphate groups), which enable them to form strong coordination bonds with
metal ions. The donor atoms (O, N) present in these ionites can combine with metal ions
to form stable complexes, enhancing their selective sorption properties. In this study, the
interaction of the ionite based on dimethylolcarbamide and orthophosphoric acid with
ISSN (E): 2181-4570 ResearchBib Impact Factor: 6,4 / 2024 SJIF 2024 = 5.073/Volume-3, Issue-5
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mercury (II) ion (Hg²⁺) was investigated. Due to the high toxicity and ecological risks of
mercury ions, their selective removal and purification are of significant scientific and
practical importance. Therefore, the complex formation characteristics of the ionite with
mercury (II) ions were thoroughly analyzed.
Infrared spectroscopy (IR spectral analysis) was used to determine the changes
occurring between the ionite and mercury (II) ions, including the participation of
functional groups and the formation of new coordination bonds. IR spectroscopy is an
effective and non-invasive method for studying the molecular structure of ionites and their
interactions with ions, providing important information on complexation processes
through shifts in peaks and changes in intensities. Thus, this study aims to identify the
potential of the ionite based on dimethylolcarbamide and orthophosphoric acid for
selective separation of mercury (II) ions and to explore its prospects for use in
environmental cleanup technologies.
Experimental Part:
Ionite Synthesis: The ionite based on dimethylolcarbamide and orthophosphoric
acid was synthesized in the laboratory. For this, dimethylolcarbamide and
orthophosphoric acid were first mixed in a certain ratio in an aqueous environment. The
mixture was stabilized under controlled temperature and pH conditions and allowed to
react. During the polycondensation process, a branched macromolecular structure was
formed through carbonyl and phosphate groups. The resulting ionite was dried, ground
into fine particles, and prepared for further analysis.
Complexation: The prepared ionite sample was reacted with a mercury (II) ion
(Hg²⁺) solution. For the complex formation process, the ionite was brought into contact
with an aqueous Hg(NO₃)₂ solution for a specified time (24 hours) under static conditions.
During the reaction process, the functional groups (carbonyl, amine, and phosphate
groups) of the ionite coordinated with the mercury ions, resulting in the formation of stable
complex compounds on the surface of the ionite. After complexation, the samples were
washed with water to remove free mercury ions, then dried.
1.
Spectral Measurement: Infrared (IR) spectra of both the initial ionite and the ionite
complexed with mercury (II) were obtained. The IR spectra were recorded in the
4000–400 cm⁻¹ range using modern Fourier Transform Infrared Spectroscopy
(FTIR) equipment. The spectral measurements were performed using the KBr pellet
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method, where ionite samples were mixed with KBr, pressed, and set in a
transparent film form.
Analysis: Based on the obtained IR spectra, the state of the ionite before and after
complexation with mercury (II) ions was compared. The spectra were analyzed for:
•
The wave numbers (cm⁻¹) corresponding to the main functional groups (O–H, N–
H, C=O, P=O, P–O–C),
•
Changes in the intensity of the peaks,
•
Shifts in peaks and the appearance of new peaks.
These changes helped to identify which functional groups were involved in the
complexation process and to determine the nature of the interaction between the ionite
and the mercury (II) ions.
Results and Discussion:
According to the results of infrared spectroscopy
, several characteristic
vibrational bands were identified in the initial IR spectrum of the ionite based on
dimethylolcarbamide and orthophosphoric acid:
Broad peaks in the 3660–3260 cm⁻¹ range (3365, 3264, 3169 cm⁻¹):
These broad and intense peaks correspond to O–H and N–H stretching vibrations. These
vibrations confirm the presence of amino and hydroxyl groups in the ionite structure.
Their broad appearance suggests enhancement due to hydrogen bonding.
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Peak at 3030 cm⁻¹:
Associated with C–H stretching vibrations, indicating the presence
of
methyl
(–CH₃)
and
methylene
(–CH₂–)
groups.
These vibrations reflect C–H bonds in the organic part of the ionite.
Peak at 2257 cm⁻¹:
A sharp and distinct peak likely corresponding to C≡N stretching
vibrations. This suggests the presence of nitrile groups or similar strong triple bond
structures in the ionite. Such groups enhance the potential for strong coordination bonds
with metal ions.
Range 1650–1500 cm⁻¹ (peaks at 1616, 1595, 1505 cm⁻¹):
This region includes C=O
stretching vibrations and deformation vibrations of N–H groups. Strong C=O stretching
typical for urea fragments is evident, confirming the successful incorporation of
dimethylolcarbamide into the ionite.
Range
1200–1000
cm⁻¹
(peaks
at
1230,
1178,
1108
cm⁻¹):
Strong peaks here correspond to P=O stretching and P–O–C bond vibrations.
These indicate active involvement of orthophosphate groups in the ionite matrix, playing
a key role in the formation of the branched structure during polycondensation.
Range 600–400 cm⁻¹ (peaks at 729, 555, 445 cm⁻¹):
Low-energy vibrations in this
region are attributed to P–O–P and possibly C–N deformation vibrations. These vibrations
point to the presence of a multi-branched and strongly bonded structural framework within
the ionite.
Overall spectral analysis:
The initial IR spectrum of the ionite clearly reveals the
presence of rich functional groups:
•
Urea fragments (C=O and N–H groups),
•
Phosphate groups (P=O and P–O–C bonds),
•
Nitrile or C≡N structures,
•
Organic C–H bonds.
The presence of these groups allows the ionite to form strong coordination
complexes with metal ions, especially heavy metals such as mercury (II).
The combination of amino, carbonyl, and phosphate groups provides the ionite with
multiple donor sites, significantly enhancing its selective sorption and complexation
properties. Furthermore, the observed broad and intense hydrogen bonding networks
suggest that the ionite may also possess improved mechanical and chemical stability.
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2. IR Spectrum of the Ionite After Complexation with Mercury (II) Ion:
Significant changes were observed in the IR spectrum of the ionite after it reacted
with mercury (II) ions, indicating that complexation had occurred.
Changes in the 3365–3160 cm⁻¹ region:
The shape and intensity of the O–H and
N–H stretching vibrations changed considerably. The previously broad peaks became
narrower and slightly sharper, suggesting the disruption or rearrangement of hydrogen
bonding. The coordination of Hg²⁺ ions with N–H and O–H groups alters the hydrogen
bonding network. This indicates a structural reorganization of the ionite molecule and
direct interaction of mercury ions with amino and hydroxyl groups.
2257 cm⁻¹ peak retained but intensified:
This peak corresponds to the C≡N
(nitrile) stretching vibration. Its retention, but with increased intensity, suggests a weak
but notable interaction between the C≡N group and mercury (II) ions. The approach of
Hg²⁺ ions changes the electron density around the nitrile group, intensifying the vibration.
This indicates that C≡N groups can also participate in metal ion binding.
1616–1505 cm⁻¹ region:
Slight shifts and intensity changes in the C=O stretching
vibration were observed. This suggests that the carbonyl group formed a coordination
bond with Hg²⁺ ions. A decrease in stretching frequency indicates reduced electron density
on the carbonyl oxygen, confirming a strong coordination interaction. Thus, carbonyl
groups played an active role in mercury binding.
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1200–1000 cm⁻¹ region:
Peaks corresponding to P=O and P–O–C stretching vibrations
intensified and slightly shifted. This is due to the interaction of phosphate group electron
clouds with mercury (II) ions, altering their vibrational characteristics. This demonstrates
that phosphate groups actively participated in the complexation process by coordinating
with Hg²⁺ ions.
600–400 cm⁻¹ region:
New deformation vibration peaks appeared in this low-
frequency region, and existing peaks showed significant shifts. These confirm the
formation of new coordination bonds of the Hg–O and Hg–N type. The distinctive
vibrations of Hg–O and Hg–N appeared as new signals in the spectrum, clearly
demonstrating the formation of a metal complex.
General Spectral Analysis:
After complexation with mercury (II) ions, the ionite spectrum showed:
•
Changes in O–H and N–H stretching regions,
•
Interaction of C≡N and C=O groups,
•
Coordination of phosphate groups,
•
Formation of new Hg–O and Hg–N bonds.
These changes confirm that complexation occurred and that several functional
groups in the ionite (amino, carbonyl, phosphate, nitrile) actively participated in binding
the metal ions. The ionite synthesized from dimethylolcarbamide and orthophosphoric
acid forms effective complexes with mercury (II) ions, where amino, carbonyl, and
phosphate groups serve as the primary coordination centers.
General Conclusion:As a result of complexation with mercury (II), the carbonyl and
phosphate groups in the ionite formed coordination bonds, anchoring mercury ions firmly
within the ionite matrix.
Mechanism
of
complex
formation:
The
ionite
synthesized
from
dimethylolcarbamide and orthophosphoric acid forms complexes with mercury (II) ions
through coordination bonds. Primarily, carbonyl (C=O), amino (N–H), and phosphate
(P=O, P–O–C) groups are actively involved in this complexation process.
Conclusion:
•
The presence of carbonyl, amino, and phosphate groups in the ionite synthesized
from dimethylolcarbamide and orthophosphoric acid was confirmed via IR spectral
analysis.
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•
The formation of strong complexes with mercury (II) ions was evidenced by shifts
in IR peaks and the appearance of new vibrational bands.
•
The study demonstrated that this ionite has great potential for selective sorption of
heavy metal ions, particularly Hg²⁺.
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