PRODUCTION OF SODIUM SULFIDE FROM ELEMENTAL SULFUR AND SODIUM HYDROXIDE: PHYSICOCHEMICAL AND THERMOANALYTIC INVESTIGATION
Аннотация
Sodium sulfide (NaS) 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production based on high-temperature reduction of sodium sulfate with coke in shaft furnaces is environmentally outdated, energy-intensive, and unable to utilize sulfatecontaining liquid wastes.This study proposes and experimentally validates an alternative low-temperature method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 NaS/NaS 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.