rus
Issue #5/2024
A.V.Blinov, Z.A.Rekhman, P.A.Trushov, A.V.Prasolova, M.A.Yasnaya, N.M.Bocharov, M.V.Vakulenko
SYNTHESIS AND STABILIZATION OF NANO-SIZED MAGNESIUM CARBONATE WITH HYDROXYETHYL CELLULOSE
SYNTHESIS AND STABILIZATION OF NANO-SIZED MAGNESIUM CARBONATE WITH HYDROXYETHYL CELLULOSE
DOI: https://doi.org/10.22184/1993-8578.2024.17.5.292.301
In this work, nanosized magnesium carbonate stabilized by hydroxyethylcellulose was synthesized by chemical precipitation in an aqueous medium. Magnesium acetate was used as a precursor, and ammonium carbonate acted as a precipitant. We optimized the synthesis technique, as a result of which we obtained a ternary surface that characterizes the dependence of the average hydrodynamic radius of nanoparticles on the input parameters. The microstructure of the surface of the obtained samples was studied by scanning electron microscopy and it was found that the sample was formed by rod-shaped particles from 2 to 6 μm in length, the particle size of which varied from 20 to 50 nm. A study of the phase composition showed that the sample consists of 3 phases with different types of crystal lattices. To determine the optimal type of interaction between magnesium carbonate particles and hydroxyethylcellulose, computer quantum chemical modeling was carried out. It was found that the process of stabilization of nano-sized magnesium carbonate and hydroxyethylcellulose is energetically favorable and the interaction occurs through the hydroxyl group. Also, to confirm the modeling results, the samples were examined by Fourier transform IR spectroscopy. Analysis of the results revealed that the interaction of MgCO3 nanoparticles occurs with the charged OH– group.
In this work, nanosized magnesium carbonate stabilized by hydroxyethylcellulose was synthesized by chemical precipitation in an aqueous medium. Magnesium acetate was used as a precursor, and ammonium carbonate acted as a precipitant. We optimized the synthesis technique, as a result of which we obtained a ternary surface that characterizes the dependence of the average hydrodynamic radius of nanoparticles on the input parameters. The microstructure of the surface of the obtained samples was studied by scanning electron microscopy and it was found that the sample was formed by rod-shaped particles from 2 to 6 μm in length, the particle size of which varied from 20 to 50 nm. A study of the phase composition showed that the sample consists of 3 phases with different types of crystal lattices. To determine the optimal type of interaction between magnesium carbonate particles and hydroxyethylcellulose, computer quantum chemical modeling was carried out. It was found that the process of stabilization of nano-sized magnesium carbonate and hydroxyethylcellulose is energetically favorable and the interaction occurs through the hydroxyl group. Also, to confirm the modeling results, the samples were examined by Fourier transform IR spectroscopy. Analysis of the results revealed that the interaction of MgCO3 nanoparticles occurs with the charged OH– group.
Теги: chemical deposition hydroxyethylcellulose ir-spectroscopy magnesium carbonate nanoparticles гидроксиэтилцеллюлоза ик-спектроскопия карбонат магния наночастицы химическое осаждение
INTRODUCTION
Magnesium carbonate is widely used in medicine as a medicinal product with antacid and anti-ulcer effect and as a means of stimulating intestinal peristalsis. In finished dosage forms it is contained in the form of the basic salt of 4MgCO3∙Mg(OH)2∙nH2O. In addition to neutralise excess acids ability, magnesium carbonate activates metabolic processes in the human body, its ions lead the musculature of intestinal walls in tone, and can also relieve spasms of smooth muscles, promotes energy conservation and its proper distribution in muscle tissues, boosts protein synthesis. It has a good effect on the heart, prevents arrhythmias, stabilises the nervous system, increases the body’s resistance to adverse environmental factors, takes part in several hundred biochemical reactions of the body, maintains an optimal balance of potassium and sodium in the blood, has anticoagulant properties, preventing the adhesion of red blood cells [1]. Nanosized magnesium carbonate, which is included in the composite with TiO2, reduces catalytic activity of TiO2 nanoparticles without blocking their ability to absorb UV radiation. This material can be used as an additive in medical and cosmetic products that absorbs UV radiation [3]. Nanoscale mesoporous magnesium carbonate is actively used as a drug carrier [4], in targeted drug delivery [6] and for diffusion-controlled drug release [7]. In addition to the use of magnesium carbonate in medicine and cosmetology, it is widely used in agriculture as a microfertiliser [5]. In [8], mesoporous nanoscale magnesium carbonate is used to improve solubility of poorly soluble drugs. The authors in [9] studied possibility of using mesoporous magnesium carbonate modified with 3-aminopropyltriethoxysilane to deliver salicylic acid in topical preparations. In [10], amorphous mesoporous magnesium carbonate was used as a drug carrier to achieve supersaturation of tolfenamic acid and rimonabant, two drug compounds with low water solubility.
RESEARCH METHODS
Magnesium carbonate nanoparticles were synthesised in aqueous biopolymer solutions.
For the magnesium carbonate synthesis, magnesium acetate (Mg(CH3COO)2), magnesium nitrate (Mg(NO3)2) and magnesium chloride MgCl2 were used as magnesium precursors. Potassium carbonate (K2CO3), ammonium carbonate ((NH4)2CO3), and sodium carbonate ((NH4)2CO3) were used as precipitant. Hydroxyethyl cellulose was used as biosolids.
The synthesis was carried out as follows: 0.8 M solution of magnesium-containing precursor was prepared, the required volume of 1% biopolymer solution was added. Next, 0.8 M precipitant solution was prepared and added using a dropping funnel to the precursor solution at a rate of 60 drops per minute. After introducing the entire precursor solution, the solution was left to stir for another 10 minutes and centrifuged for 5 minutes at 3000 rpm. The operation was repeated 4 times. The precipitate was then dried at 110 °C for 8 hours.
The average hydrodynamic radius of the obtained magnesium carbonate samples was determined by photon correlation spectroscopy on Photocor-Complex (Antec-97 Ltd., Russia). The ζ-potential of the obtained samples was determined by acoustic and electroacoustic spectroscopy on the DT-1202 unit manufactured by "Dispersion Technology" Inc., USA.
Table 1 presents the parameters of magnesium carbonate nanoparticles synthesis stabilised by hydroxyethylcellulose. Preparation of solutions was performed at the rate of 1 litre.
To optimise the experimental parameters, a multivariate experiment with three input parameters and three variation levels was carried out using an orthogonal plan of 9 experiments in 3-fold repetition. The output parameters were mean hydrodynamic particle radius (rср) and electrokinetic potential (ζ-potential). The experimental data were processed using Statistica software package, version 12.0.
To study phase composition and microstructure, the samples were studied by X-ray phase analysis on X-ray diffractometer "PANalytical Empyrean", and scanning electron microscopy on MIRA-LMH of Tescan company.
Quantum-chemical modelling of the stabilisation process of magnesium carbonate nanoparticles by hydroxyethylcellulose was carried out in the QChem programme using the IQmol molecular editor. The calculation was carried out on the data processing centre equipment (Schneider Electric) of the Federal State Autonomous Educational Institution of Higher Education of the North Caucasus Federal University. The total energy and other characteristics were calculated using following parameters: calculation: Energy, method: HF, basis: 3–21G, convergence – 5, force field – Ghemical.
To confirm the quantum chemical modelling results, our samples were studied by IR spectroscopy using a Fourier 1201 IR spectrometer.
RESULTS
In the first stage, optimisation of the methodology for the magnesium carbonate nanoparticles synthesis was carried out and the results of the study are presented in Table 2.
As a result of mathematical data processing, a three-dimensional ternary surface describing relationship with the mean hydrodynamic radius and the concentrations of precursor, reducing agent and stabiliser was obtained and is shown in Fig.1.
At the next stage, the obtained sample was examined by scanning electron microscopy. The obtained SEM images are presented in Fig.2.
The obtained sample was studied by X-ray phase analysis. The obtained diffractogram is presented in Fig.3.
Further, computer quantum-chemical modelling of magnesium carbonate nanoparticles stabilized by hydroxyethylcellulose (HEC) was carried out. The obtained data are presented in Fig.4 and Table 3.
At the next stage the obtained sample was studied by IR spectroscopy. The obtained data are presented in Fig.5.
DISCUSSION
As a result of optimisation of the methodology for the synthesis of nanosized magnesium carbonate, it was found that the largest average hydrodynamic radius is possessed by sample No. 3 (832 nm), and the smallest – by sample No. 9 (149 nm). It is worth noting that studies of the samples by acoustic and electroacoustic spectroscopy showed that the electrokinetic potential values do not exceed 1 mV. This means fact that in this interaction the steric type of stabilisation prevails, and the polymer molecule does not have a significant charge on the surface.
Analysis of obtained ternary surface showed that the greatest influence on the particle size of magnesium carbonate is exerted by the ratio between the concentrations of precursor (magnesium acetate) and precipitant (ammonium carbonate). At a precipitant content of about 0.036 mol/L, an increase in the mean hydrodynamic radius of magnesium carbonate particles up to 1150 nm was observed. The average hydrodynamic radius of magnesium carbonate particles also increases when the content of hydroxyethylcellulose increases up to 0.0002 mol/l. The optimal parameters for obtaining magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose are: precursor content 0.036 mol/L, precipitant content 0.012 mol/L, and maximum biopolymer concentration 0.0002 mol/L.
Analysis of SEM micrographs showed that the sample is represented by rod-shaped particles with lengths ranging from 2 to 6 μm, which in turn consist of magnesium carbonate nanoparticles with sizes ranging from 20 to 50 nm.
Analysis of the obtained diffractogram showed that the sample contains anhydrous magnesium carbonate, magnesium carbonate in the form of crystalline hydrate (MgCO3 · 5H2O), Mg2(CO3)(OH)2 · 3H2O. It is important to note that anhydrous magnesium carbonate (MgCO3) has a trigonal crystal lattice with R 3(-)c space group, MgCO3 · 5H2O has a monoclinic crystal lattice with P 2(1)/c space group, mineral "Artinita" (Mg2(CO3)(OH)2 · 3H2O) – monoclinic crystal lattice with C 2/m space group, magnesium oxide (MgO) – cubic crystal lattice with F m3m space group.
Computer quantum-chemical modelling allowed us to determine that all presented compounds are energetically advantageous (∆E>462,340 kcal/mol for magnesium carbonate and ∆E>736,170 kcal/mol for basic magnesium carbonate). Based on the optimum values of chemical stiffness and total energy difference, the most probable interaction of magnesium carbonate with hydroxyethyl cellulose was determined. Thus, the optimal interaction (∆E = 462.379 kcal/mol, η = 0.075 eV for magnesium carbonate) is the coupling via ethylhydroxyl group attached to C6 residue of glucopyranose, presented in Fig.4.
Analysis of the IR spectrum of magnesium carbonate nanoparticles stabilised with hydroxyethylcellulose showed that in the region from 800 to 1400 cm-1, presence of bands characteristic of deformation vibrations of the CH3 group (849–1136 cm–1) and deformation plane vibrations of the hydroxyl group O–H (1359 cm–1) were observed. Analysis of the IR spectrum of hydroxyethylcellulose showed that in the region from 2500 to 3500 cm–1 presence of bands of valence bond vibrations is observed: in the range from 3290 to 3495 cm–1 are vibrations of charged –OH- groups. In the region from 2900 to 3250 cm–1, bands characteristic of deformation vibrations of the CH3 bond are observed. In the IR spectrum of hydroxyethylcellulose in the region from 1100 to 1900 cm–1 the bands characteristic for deformation vibrations are observed: at 1410 and 1649 cm–1 – symmetric vibrations of OH group, and the region from 1490 to 1580 cm–1 corresponds to vibrations of CH2 bond. In IR spectrum of the hydroxyethylcellulose site in the region from 500 cm–1 to 1050 cm–1 presence of bands characteristic of deformation vibrations of CH2 and CH3 bonds was found.
Analysis of the IR spectrum of magnesium carbonate nanoparticles showed that in the region from 2200 to 3000 cm–1 presence of bands characteristic of valence vibrations of NH3+, NH2+, NH+ groups (2291 cm–1) and C–H group (2895–2930 cm–1) was observed, and due to residual presence of ammonium carbonate and magnesium acetate at the end of magnesium carbonate nanoparticles decantation process. In the region from 1400 to 1900 cm–1, presence of a band characteristic of deformation plane vibrations of the O–H group (1414 cm–1) is observed. Presence of a band characteristic of the C–C group (1529 cm–1) and bands characteristic of the valence vibrations of the C=O group (1661 to 1896 cm–1) are observed.
In the region from 400 to 1200 cm–1 presence of bands characteristic of deformation out-of-plane vibrations of the O–H group (481–697 cm–1), deformation vibrations of the CH3 group (848–1104 cm–1) is observed, which is due to residual presence of magnesium acetate upon completion of decantation process of magnesium carbonate nanoparticles. As a result, it was found that in the spectrum of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose in the region from 1300 to 1400 cm–1 there is a significant drop in bands intensity characterising the deformation plane vibrations of the O–H group. Thus, it can be concluded that interaction of magnesium carbonate nanoparticles with hydroxyethylcellulose occurs with the ethylhydroxyl group, which is consistent with the quantum chemical modelling results.
CONCLUSIONS
In this paper, the synthesis of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose was carried out, as well as the preparation methodology optimisation. It was found that the largest average hydrodynamic radius is possessed by sample No. 3 (832 nm) and the smallest by sample No. 9 (149 nm). In turn, the electrokinetic potential of the studied samples does not exceed 1 mV.
Ternary surface analysis showed that the greatest influence on the particle size of magnesium carbonate is exerted by the ratio between concentrations of precursor (magnesium acetate) and precipitant (ammonium carbonate). The optimal parameters for the synthesis of nanosized magnesium carbonate were determined: precursor content 0.036 mol, precipitant – 0.012 mol, and maximum concentration of biopolymer 0.15 grams. The particle size at these parameters varies from 120 to 175 nm.
Scanning electron microscopy revealed that the sample is represented by rod-shaped particles ranging from 2 to 6 μm in length, with particle sizes ranging from 20 to 50 nm.
The analysis of phase composition showed that 4 phases are present in the sample: anhydrous magnesium carbonate (trigonal crystal lattice), magnesium carbonate in the form of crystalline hydrate (MgCO3 · 5H2O) has a monoclinic crystal lattice, Mg2(CO3)(OH)2 · 3H2O has a monoclinic crystal lattice with space group C 2/m, magnesium oxide (MgO) has a cubic crystal lattice with space group F m3m.
Computer quantum-chemical modelling of interaction of magnesium carbonate molecule with hydroxyethylcellulose has shown that the total energy of interaction is more than 462,340 kcal/mol for magnesium carbonate and 736,170 kcal/mol for basic magnesium carbonate, which indicates the energetic benefit of this process. The coupling via ethyl hydroxyl group attached to the C6 residue of glucopyranose was found to be the favourable option for interaction.
The study of samples by IR spectroscopy showed that in the spectrum of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose in the region from 1300 to 1400 cm-1 there is a significant drop in bands intensity characterising deformation plane vibrations of the O-H group. Accordingly, interaction of magnesium carbonate nanoparticles with hydroxyethylcellulose occurs with ethylhydroxyl group, which is confirmed by the data obtained in the course of quantum-chemical modelling.
ACKNOWLEDGMENTS
This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation (project FSRN-2023-0037).
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Magnesium carbonate is widely used in medicine as a medicinal product with antacid and anti-ulcer effect and as a means of stimulating intestinal peristalsis. In finished dosage forms it is contained in the form of the basic salt of 4MgCO3∙Mg(OH)2∙nH2O. In addition to neutralise excess acids ability, magnesium carbonate activates metabolic processes in the human body, its ions lead the musculature of intestinal walls in tone, and can also relieve spasms of smooth muscles, promotes energy conservation and its proper distribution in muscle tissues, boosts protein synthesis. It has a good effect on the heart, prevents arrhythmias, stabilises the nervous system, increases the body’s resistance to adverse environmental factors, takes part in several hundred biochemical reactions of the body, maintains an optimal balance of potassium and sodium in the blood, has anticoagulant properties, preventing the adhesion of red blood cells [1]. Nanosized magnesium carbonate, which is included in the composite with TiO2, reduces catalytic activity of TiO2 nanoparticles without blocking their ability to absorb UV radiation. This material can be used as an additive in medical and cosmetic products that absorbs UV radiation [3]. Nanoscale mesoporous magnesium carbonate is actively used as a drug carrier [4], in targeted drug delivery [6] and for diffusion-controlled drug release [7]. In addition to the use of magnesium carbonate in medicine and cosmetology, it is widely used in agriculture as a microfertiliser [5]. In [8], mesoporous nanoscale magnesium carbonate is used to improve solubility of poorly soluble drugs. The authors in [9] studied possibility of using mesoporous magnesium carbonate modified with 3-aminopropyltriethoxysilane to deliver salicylic acid in topical preparations. In [10], amorphous mesoporous magnesium carbonate was used as a drug carrier to achieve supersaturation of tolfenamic acid and rimonabant, two drug compounds with low water solubility.
RESEARCH METHODS
Magnesium carbonate nanoparticles were synthesised in aqueous biopolymer solutions.
For the magnesium carbonate synthesis, magnesium acetate (Mg(CH3COO)2), magnesium nitrate (Mg(NO3)2) and magnesium chloride MgCl2 were used as magnesium precursors. Potassium carbonate (K2CO3), ammonium carbonate ((NH4)2CO3), and sodium carbonate ((NH4)2CO3) were used as precipitant. Hydroxyethyl cellulose was used as biosolids.
The synthesis was carried out as follows: 0.8 M solution of magnesium-containing precursor was prepared, the required volume of 1% biopolymer solution was added. Next, 0.8 M precipitant solution was prepared and added using a dropping funnel to the precursor solution at a rate of 60 drops per minute. After introducing the entire precursor solution, the solution was left to stir for another 10 minutes and centrifuged for 5 minutes at 3000 rpm. The operation was repeated 4 times. The precipitate was then dried at 110 °C for 8 hours.
The average hydrodynamic radius of the obtained magnesium carbonate samples was determined by photon correlation spectroscopy on Photocor-Complex (Antec-97 Ltd., Russia). The ζ-potential of the obtained samples was determined by acoustic and electroacoustic spectroscopy on the DT-1202 unit manufactured by "Dispersion Technology" Inc., USA.
Table 1 presents the parameters of magnesium carbonate nanoparticles synthesis stabilised by hydroxyethylcellulose. Preparation of solutions was performed at the rate of 1 litre.
To optimise the experimental parameters, a multivariate experiment with three input parameters and three variation levels was carried out using an orthogonal plan of 9 experiments in 3-fold repetition. The output parameters were mean hydrodynamic particle radius (rср) and electrokinetic potential (ζ-potential). The experimental data were processed using Statistica software package, version 12.0.
To study phase composition and microstructure, the samples were studied by X-ray phase analysis on X-ray diffractometer "PANalytical Empyrean", and scanning electron microscopy on MIRA-LMH of Tescan company.
Quantum-chemical modelling of the stabilisation process of magnesium carbonate nanoparticles by hydroxyethylcellulose was carried out in the QChem programme using the IQmol molecular editor. The calculation was carried out on the data processing centre equipment (Schneider Electric) of the Federal State Autonomous Educational Institution of Higher Education of the North Caucasus Federal University. The total energy and other characteristics were calculated using following parameters: calculation: Energy, method: HF, basis: 3–21G, convergence – 5, force field – Ghemical.
To confirm the quantum chemical modelling results, our samples were studied by IR spectroscopy using a Fourier 1201 IR spectrometer.
RESULTS
In the first stage, optimisation of the methodology for the magnesium carbonate nanoparticles synthesis was carried out and the results of the study are presented in Table 2.
As a result of mathematical data processing, a three-dimensional ternary surface describing relationship with the mean hydrodynamic radius and the concentrations of precursor, reducing agent and stabiliser was obtained and is shown in Fig.1.
At the next stage, the obtained sample was examined by scanning electron microscopy. The obtained SEM images are presented in Fig.2.
The obtained sample was studied by X-ray phase analysis. The obtained diffractogram is presented in Fig.3.
Further, computer quantum-chemical modelling of magnesium carbonate nanoparticles stabilized by hydroxyethylcellulose (HEC) was carried out. The obtained data are presented in Fig.4 and Table 3.
At the next stage the obtained sample was studied by IR spectroscopy. The obtained data are presented in Fig.5.
DISCUSSION
As a result of optimisation of the methodology for the synthesis of nanosized magnesium carbonate, it was found that the largest average hydrodynamic radius is possessed by sample No. 3 (832 nm), and the smallest – by sample No. 9 (149 nm). It is worth noting that studies of the samples by acoustic and electroacoustic spectroscopy showed that the electrokinetic potential values do not exceed 1 mV. This means fact that in this interaction the steric type of stabilisation prevails, and the polymer molecule does not have a significant charge on the surface.
Analysis of obtained ternary surface showed that the greatest influence on the particle size of magnesium carbonate is exerted by the ratio between the concentrations of precursor (magnesium acetate) and precipitant (ammonium carbonate). At a precipitant content of about 0.036 mol/L, an increase in the mean hydrodynamic radius of magnesium carbonate particles up to 1150 nm was observed. The average hydrodynamic radius of magnesium carbonate particles also increases when the content of hydroxyethylcellulose increases up to 0.0002 mol/l. The optimal parameters for obtaining magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose are: precursor content 0.036 mol/L, precipitant content 0.012 mol/L, and maximum biopolymer concentration 0.0002 mol/L.
Analysis of SEM micrographs showed that the sample is represented by rod-shaped particles with lengths ranging from 2 to 6 μm, which in turn consist of magnesium carbonate nanoparticles with sizes ranging from 20 to 50 nm.
Analysis of the obtained diffractogram showed that the sample contains anhydrous magnesium carbonate, magnesium carbonate in the form of crystalline hydrate (MgCO3 · 5H2O), Mg2(CO3)(OH)2 · 3H2O. It is important to note that anhydrous magnesium carbonate (MgCO3) has a trigonal crystal lattice with R 3(-)c space group, MgCO3 · 5H2O has a monoclinic crystal lattice with P 2(1)/c space group, mineral "Artinita" (Mg2(CO3)(OH)2 · 3H2O) – monoclinic crystal lattice with C 2/m space group, magnesium oxide (MgO) – cubic crystal lattice with F m3m space group.
Computer quantum-chemical modelling allowed us to determine that all presented compounds are energetically advantageous (∆E>462,340 kcal/mol for magnesium carbonate and ∆E>736,170 kcal/mol for basic magnesium carbonate). Based on the optimum values of chemical stiffness and total energy difference, the most probable interaction of magnesium carbonate with hydroxyethyl cellulose was determined. Thus, the optimal interaction (∆E = 462.379 kcal/mol, η = 0.075 eV for magnesium carbonate) is the coupling via ethylhydroxyl group attached to C6 residue of glucopyranose, presented in Fig.4.
Analysis of the IR spectrum of magnesium carbonate nanoparticles stabilised with hydroxyethylcellulose showed that in the region from 800 to 1400 cm-1, presence of bands characteristic of deformation vibrations of the CH3 group (849–1136 cm–1) and deformation plane vibrations of the hydroxyl group O–H (1359 cm–1) were observed. Analysis of the IR spectrum of hydroxyethylcellulose showed that in the region from 2500 to 3500 cm–1 presence of bands of valence bond vibrations is observed: in the range from 3290 to 3495 cm–1 are vibrations of charged –OH- groups. In the region from 2900 to 3250 cm–1, bands characteristic of deformation vibrations of the CH3 bond are observed. In the IR spectrum of hydroxyethylcellulose in the region from 1100 to 1900 cm–1 the bands characteristic for deformation vibrations are observed: at 1410 and 1649 cm–1 – symmetric vibrations of OH group, and the region from 1490 to 1580 cm–1 corresponds to vibrations of CH2 bond. In IR spectrum of the hydroxyethylcellulose site in the region from 500 cm–1 to 1050 cm–1 presence of bands characteristic of deformation vibrations of CH2 and CH3 bonds was found.
Analysis of the IR spectrum of magnesium carbonate nanoparticles showed that in the region from 2200 to 3000 cm–1 presence of bands characteristic of valence vibrations of NH3+, NH2+, NH+ groups (2291 cm–1) and C–H group (2895–2930 cm–1) was observed, and due to residual presence of ammonium carbonate and magnesium acetate at the end of magnesium carbonate nanoparticles decantation process. In the region from 1400 to 1900 cm–1, presence of a band characteristic of deformation plane vibrations of the O–H group (1414 cm–1) is observed. Presence of a band characteristic of the C–C group (1529 cm–1) and bands characteristic of the valence vibrations of the C=O group (1661 to 1896 cm–1) are observed.
In the region from 400 to 1200 cm–1 presence of bands characteristic of deformation out-of-plane vibrations of the O–H group (481–697 cm–1), deformation vibrations of the CH3 group (848–1104 cm–1) is observed, which is due to residual presence of magnesium acetate upon completion of decantation process of magnesium carbonate nanoparticles. As a result, it was found that in the spectrum of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose in the region from 1300 to 1400 cm–1 there is a significant drop in bands intensity characterising the deformation plane vibrations of the O–H group. Thus, it can be concluded that interaction of magnesium carbonate nanoparticles with hydroxyethylcellulose occurs with the ethylhydroxyl group, which is consistent with the quantum chemical modelling results.
CONCLUSIONS
In this paper, the synthesis of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose was carried out, as well as the preparation methodology optimisation. It was found that the largest average hydrodynamic radius is possessed by sample No. 3 (832 nm) and the smallest by sample No. 9 (149 nm). In turn, the electrokinetic potential of the studied samples does not exceed 1 mV.
Ternary surface analysis showed that the greatest influence on the particle size of magnesium carbonate is exerted by the ratio between concentrations of precursor (magnesium acetate) and precipitant (ammonium carbonate). The optimal parameters for the synthesis of nanosized magnesium carbonate were determined: precursor content 0.036 mol, precipitant – 0.012 mol, and maximum concentration of biopolymer 0.15 grams. The particle size at these parameters varies from 120 to 175 nm.
Scanning electron microscopy revealed that the sample is represented by rod-shaped particles ranging from 2 to 6 μm in length, with particle sizes ranging from 20 to 50 nm.
The analysis of phase composition showed that 4 phases are present in the sample: anhydrous magnesium carbonate (trigonal crystal lattice), magnesium carbonate in the form of crystalline hydrate (MgCO3 · 5H2O) has a monoclinic crystal lattice, Mg2(CO3)(OH)2 · 3H2O has a monoclinic crystal lattice with space group C 2/m, magnesium oxide (MgO) has a cubic crystal lattice with space group F m3m.
Computer quantum-chemical modelling of interaction of magnesium carbonate molecule with hydroxyethylcellulose has shown that the total energy of interaction is more than 462,340 kcal/mol for magnesium carbonate and 736,170 kcal/mol for basic magnesium carbonate, which indicates the energetic benefit of this process. The coupling via ethyl hydroxyl group attached to the C6 residue of glucopyranose was found to be the favourable option for interaction.
The study of samples by IR spectroscopy showed that in the spectrum of magnesium carbonate nanoparticles stabilised by hydroxyethylcellulose in the region from 1300 to 1400 cm-1 there is a significant drop in bands intensity characterising deformation plane vibrations of the O-H group. Accordingly, interaction of magnesium carbonate nanoparticles with hydroxyethylcellulose occurs with ethylhydroxyl group, which is confirmed by the data obtained in the course of quantum-chemical modelling.
ACKNOWLEDGMENTS
This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation (project FSRN-2023-0037).
PEER REVIEW INFO
Editorial board thanks the anonymous reviewer(s) for their contribution to the peer review of this work. It is also grateful for their consent to publish papers on the journal’s website and SEL eLibrary eLIBRARY.RU.
Declaration of Competing Interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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