Investigation of the Conditions for Obtaining the Silver Thioarsenate Compound from the AgNO₃-As₂S₅-H₂O System and Investigation of the Properties of the Obtained Silver Thioarsenate Compound

Abstract

This study systematically investigated the synthesis conditions and characterized the properties of silver thioarsenate compounds derived from the AgNO3-As2S5-H2O system. The optimal parameters for compound formation under hydrothermal conditions including molar ratios, pH, temperature, and reaction time were determined through controlled precipitation methods. A phase-pure silver thioarsenate compound was yielded at the stoichiometric AgNO3:As2S5 molar ratio of 15:4, pH range of 4-5, and reaction temperature of 323-343 K. The distinctiveness of the synthesized compound was confirmed through thermogravimetric and X-ray phase analyses. Differential thermal analysis revealed a melting point of 888.2 K for the synthesized silver thioarsenate. Scanning electron microscopy indicated that the compound consists of aggregated spherical particles with sizes ranging from 500 to 800 nm. The chemical reaction for the formation of silver thioarsenate was elucidated, and its thermodynamic parameters were calculated. Chemical analysis, concerning the product yield and filtrate composition, allowed for the specification of the compound's empirical formula. Furthermore, the solubility of the synthesized silver thioarsenate was investigated in various 1 M acidic and alkaline solutions (HCl, H2SO4, HNO3, KOH, and NH4OH) over different time intervals. The compound demonstrated insolubility in 1 M HCl and H2SO4, while significant time-dependent dissolution was observed in 1 M HNO3, KOH, and NH4OH solutions. Elemental analysis further determined the mass and atomic ratios of silver, arsenic, and sulfur within the synthesized silver thioarsenate compound. The study highlights the critical role of synthesis conditions in tailoring material properties, providing a foundational framework for scalable production and further functional exploration of silver thioarsenates.