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№ 1 (127)_ДД химия и биология_январь. 2025 г.
INORGANIC CHEMISTRY
DOI: 10.32743/UniChem.2025.127.1.18962
STUDY OF THE CONDITIONS FOR THE SYNTHESIS OF ARSENIC(V) SULFIDE BY THE SOLVOTHERMAL METHOD
Huseyn Imanov Abulfaz
Doctor of Philosophy in Inorganic chemistry Lecturer at the Chemistry Department and Senior Specialist at the Technological Transfer and Innovation Department of the Nakhchivan State University,
Azerbaijan, Nakhchivan city, University Campus Email:huseyn. [email protected], huseyn. imanov@ndu. edu. az
ИЗУЧЕНИЕ УСЛОВИЙ СИНТЕЗА СУЛЬФИД МЫШЬЯКА^) СОЛЬВОТЕРМИЧЕСКИМ МЕТОДОМ
Гусейн Иманов Абульфаз
д-р философии по неорганической химии, преподаватель кафедры химии, ст. специалист кафедры технологического трансфера и инноваций Нахчыванского государственного университета, Азербайджан, г. Нахчыван, университетский городок Email:huseyn. imanov1991@gmail. com, huseyn. imanov@ndu. edu. az
ABSTRACT
The article provides information on the results of research into the conditions for obtaining As2S5 in an organic medium. Based on the results of thermogravimetric (TG) and scanning electron microscopic (SEM) analysis, it was determined that As2S5 is obtained when sodium arsenate solution is treated with thioacetamide in an acidic medium (pH = 02). As2S5 sample is kept with stirring for 8-10 hours in the temperature range of 273-283 K a golden-yellow cotton-like precipitate forms in the beaker where the experiment was conducted. Based on TG results, it was determined that mass loss of As2S5 occurs after 573 K temperature. SEM images of the obtained As2S5 compound were taken at 5 and 10 дт areas and it was determined that the obtained compound consists of nanoparticles. According to the results of ultraviolet spectroscopy, the width of the forbidden zone of As2S5 is Eg0 = 2.55 eV.
АННОТАЦИЯ
В статье приведены сведения о результатах исследования условий получения As2S5 в органической среде. На основании результатов термогравиметрического (ТГ) и сканирующего электронного микроскопа (СЭМ) анализа установлено, что As2S5 получается при обработке раствора арсената натрия тиоацетамидом в кислой среде (рН = 0-2). Образец As2S5 выдерживают при перемешивании в течение 8-10 часов в интервале температур 273283 К. В стакане, где проводился эксперимент, выпадает золотисто-желтый ватообразный осадок. На основании результатов ТГ определено, что потеря массы As2S5 происходит после температуры 573 К. Получены СЭМ-изображения полученного соединения As2S5 на участках 5 и 10 мкм и установлено, что полученное соединение состоит из наночастиц. По результатам ультрафиолетовой спектроскопии ширина запрещенной зоны As2S5 составляет Eg0 = 2,55 эВ.
Keywords: arsenic(V) sulfide, thermogravimetric analysis, micromorphology, thin film.
Ключевые слова: сульфид мышьяка(У), термогравиметрический анализ, микроморфология, тонкая пленка.
Introduction. The sulfide precipitation mechanism of arsenic(III/V) acid has been further elucidated through the use of advanced analytical methods and sophisticated characterization tools in recent years [7,p.2]. Under gentle hydrothermal and solvothermal conditions using highly polar solvents like water, methanol, and amines at temperatures between 100 and 200 °C, a wide
array of chalcogenidoarsenate anions and ligands has been created in the presence of As2Ss [4,p.528; 6,p.919].
In this study authors successfully determined the mechanism of thermal decomposition for the arsenic sulfide sample and calculated the apparent activation energy using the Kissinger and Ozawa methods [2,p.2].
Библиографическое описание: Imanov H.A. STUDY OF THE CONDITIONS FOR THE SYNTHESIS OF ARSENIC(V) SULFIDE BY THE SOLVOTHERMAL METHOD // Universum: химия и биология : электрон. научн. журн. 2025. 1(127). URL: https://7universum.com/ru/nature/archive/item/18962
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The research on glassy As2S5 has delved into how synthesis conditions affect its thermal expansion and structural properties [8,p.58]. The study of six different compositions of As-S glasses during thermal evaporation from a Knudsen cell within the temperature range of 400 - 520 K has uncovered the intricate and complex nature of the vapor flows of these glasses [5,p.31]. Besides, thermodynamic modeling has been studied for the As-S system. Experimental findings indicate that As2S5 is a metastable phase at moderate pressures [1,p.228; 3,p.98].
Chemicals. All of the chemicals used during this study are of analytical grade and provided as high purity products. List of chemicals used: 1. Sodium arsenate (Na3AsO4-12H2O) - American Elements CAS No:13464-38-5; 2. Thioacetamide (CHsCSN^-BEKTOH CAS No:62-55-5; 3. Polyethylene glycol (H(OCH2CH2)nOH) -Merck KGaA CAS No: 25322-68-3. Ultra-clean water used in laboratory studies was provided by EMD Millipore ZRXSP0D01 device.
Experimental part. To study the synthesis conditions of As2S5 in polyethylene glycol, 0.848 g of sodium
arsenate salt containing 0.150 g of arsenic is dissolved in 20 ml of a solution containing 2.0 g of polyethylene glycol. The solution is transferred to the test vessel and after adding 0.2271 g of thioacetamide according to the amount of arsenic, the pH of the solution is adjusted to 2. The sample is kept with stirring for 8-10 hours in the temperature range of 273-283 K. After the process is completed, the precipitate is filtered through a glass filter, washed first with distilled water and then with ultrapure water (EMD Millipore ZRXSP0D01). At the end of the process, the sample is washed with ethyl alcohol and dried in vacuum at 323-333 K.
Results and discussion. Depending on the synthesis of chalcogenides in aqueous and organic media, compounds corresponding to different stoichiometric compositions can be obtained, for example, As2S5.48, As2S4, As2S3. Therefore, the composition of the synthesized As2S5 (As:S ratio) was determined using a NETZSCH STA 449F3 deri-vatograph. The results of the TQ analysis are given in Figure 1.
Figure 1. TQ analysis of As2S5 obtained at 273-283 K and 10 h
As can be seen from the figure, the sample was heated to 873 K and no mass loss occurred in the sample up to 573 K. This indicates that there is no free sulfur in the sample. The mass loss in the temperature range of 573 - 773 K occurs due to the removal of sulfur gases and arsenic oxides formed as a result of the oxidation of As2S5. According to the results in the graph, the complete removal of As2Ss (15.76 mg) during the oxidation of 15.9 mg of the sample confirmed that the sample consists of As2S5 and corresponds to the formula As2Ss.
SEM (Hitachi TM-3000) images of As2Ss particles synthesized in polyethylene glycol medium were taken (Figure 2).
We believe that the preparation and formation of As2S5 nanoparticles by the developed method depended on temperature, time, and liquid phase. Thus, at the beginning of the experiment, during the interaction of arsenic(V) and sulfur in polyethylene glycol medium, the color of the solution turns yellow (pH-12). After 3 hours, the pH of the solution is adjusted to 2.0-3.0. After 10 hours, a golden-yellow cotton-like precipitate forms in the beaker where the experiment was conducted.
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a b
Figure 2. AS2S5 nanoparticles (a) 5 ¡m, b) 10.0 ¡im magnification
As2S5 thin film was prepared by screen printing. Thus, As2S5 obtained in polyethylene glycol medium was dissolved in ethylenediamine solution and the obtained solution was applied on a glass substrate and
dried in vacuum at a temperature of 323-333 K. The optical properties of the prepared As2Ss thin film were studied.
Figure 3. Absorption spectrum of a thin layer of AS2S5
The absorption spectrum of the As2Ss thin film was recorded on a U-5100 Hitachi ultraviolet spectrophotometer, the optical absorption curve was shown and the dependences were constructed (Figure 3).
It is known that it is possible to calculate the width of the forbidden bandgap of semiconductor compounds using the Tauc formula
(ahv)^n = A(hv- Eg).
Here A- is a constant, Eg- is the band gap width of the semiconductor, and hv- is the energy of the photon. n- can take four different values depending on the
type of transition. Thus, for a permitted direct transition it takes the values n=l2, for a permitted oblique transition it takes the values n=2, for a forbidden direct transition it takes the values n=32, and for a forbidden oblique transition it takes the values n=3.
The relation n=l2 is true for the arsenic(V) sulfide compound as a flat-band semiconductor. To determine the band gap width of the arsenic(V) sulfide compound, a curve of (ahv)2 versus hv was constructed based on the values obtained from the U-5100 Hitachi ultraviolet spectrophotometer (Figure 4).
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Figure 4. Absorption spectrum of arsenic (V) sulfide nanocompound
Based on the intersection of the straight line region with the abscissa axis (hv) in the curve constructed based on the values of the calculations performed according to the equation, it was determined that the band gap width of the sample is Eg0 = 2.55 eV. This indicates that the arsenic(V) sulfide nanocompound is a wide-bandgap semiconductor.
Conclusion.
composition was confirmed by TG and SEM analysis methods. It was determined that mass loss in the temperature range of 573-773 K occurs due to the removal of sulfur gases and arsenic oxides formed as a result of the oxidation of As2S5. In addition, the bandgap width of the As2S5 thin layer was determined to be Eg0=2.55 eV based on the UV analysis values and using the Tauc formula.
The As2S5 compound was obtained in an organic medium based on Na3AsO4 and thioacetamide and its
References:
1. Babanly M. B., Thermodynamic properties of arsenic sulfides studied by emf measurements / Muradova, G. V., Il'yasly, T. M., & Babanly, D. M. [et al.] // Inorganic Materials, - 2011, № 47, p-227-230.
2. Castro K., Study of the Reaction Mechanisms during the Thermal Decomposition of Arsenic Sulfide (V) at High Temperatures under Non-Isothermal Conditions / Balladares, E., Jerez, O., Perez-Tello, M., & Aracena, Ä [et al.] // Minerals, - 2022, № 12(11), p-1-13.
3. Emelina, A. L., Phase diagram of the As-S system / Alikhanian, A. S., Steblevskii, A. V., & Kolosov, E. N [et al.] // Inorganic materials, - 2007, № 43, p- 95-104.
4. Imanov, H., & Huseynov, Q., Investigation of the Acquisition Conditions of TbAsS4 Compound in the Aquatic Environment // Journal of the Turkish Chemical Society Section A: Chemistry, - 2021, № 8(2), p- 527-534.
5. Ivanitsky, V., Mass-spectra of Evaporation of Glasses in As-S System / Kovtunenko, V., Meshko, R., Ryaboschuk, M., Myroslav, S., & Miroszlav, S // Science and Education a New Dimension. Natural and Technical Sciences, -2017, V(16), Issue: 148, p-30-33.
6. Kromm, A., Almsick, T. V., & Sheldrick, W. S., Solvothermal synthesis and structure of chalcogenidoarsenate anions // Zeitschrift für Naturforschung B, -2010, № 65(8), p-918-936.
7. Xu, H., Treatment of Acidic Solutions Containing As (III) and As (V) by Sulfide Precipitation: Comparison of Precipitates and Sulfurization Process / Wang, Y., Yao, L., Ke, Y., Luo, Y., Zhang, L., ... & Min, X // Metals, -2023, № 13(4), p-1-14.
8. Росола, I. Й., & Цигика, В. В., Вплив умов одержання на лшшне розширення i структуру склоподiбного As2S5 / Науковий вюник Ужгородського ушверситету // Сер.: Фiзика, -2010, № (28), c-57-63.
