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Scientific Object Identifier: http://s-o-i.org/1.1/TAS-12-152-6
DOI: https://dx.doi.org/10.15863/TAS.2025.12.152.6
Language: English
Citation: Adilkhanova, M., & Erkayev, A. (2025). Production of sodium sulfide from elemental sulfur and sodium hydroxide: physicochemical and thermoanalytic investigation. ISJ Theoretical & Applied Science, 12 (152), 31-34. Soi: https://s-o-i.org/1.1/TAS-12-152-6 Doi: https://dx.doi.org/10.15863/TAS.2025.12.152.6 |
Pages: 31-34
Published: 30.12.2025
Abstract: Sodium sulfide (Na?S) is an industrially important compound widely used in metallurgy, leather processing, textile dyeing, and chemical synthesis. Conventional production based on high-temperature reduction of sodium sulfate with coke in shaft furnaces is environmentally outdated, energy-intensive, and unable to utilize sulfate-containing liquid wastes. This study proposes and experimentally validates an alternative low-temperature method for producing sodium sulfide through the reaction of elemental sulfur with aqueous sodium hydroxide. NaOH solutions of 30%, 40%, and 50% concentration were reacted with sulfur under controlled stirring at temperatures above 130 °C. The physicochemical properties of the resulting Na?S/Na?S? mixtures—including pH, density, and viscosity—were measured as functions of sulfur content and temperature. Results show a monotonic decrease in pH with increasing sulfur concentration, while density and viscosity increase with sulfur content and decrease with temperature. Thermal analysis (TG/DTA/DTG) revealed a three-stage mass loss totaling 36.12% and an exothermic transition at 218.9 °C indicative of structural rearrangements in polysulfide species. The findings demonstrate that the sulfur–NaOH method provides a cleaner, waste-free, and economically viable alternative to traditional sodium sulfide production technologies.
Key words: Sodium sulfide; Na?S; polysulfides; sodium hydroxide; sulfur; thermal analysis; TG/DTA; viscosity; density; pH; green technology; waste-free process; sulfate-containing wastes; chemical synthesis.
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