Solubility of orpiment (As2S3) in Na2S-H2O at 50–200°C and 100–1500 bars, with geological applications

Thermodynamic model for arsenic speciation in sulfidic waters: A novel use of ab initio computations

“…Realgar (AsS) is the most likely candidate, but other possibilities exist. Production of realgar residues during orpiment dissolution has been noticed by Weissberg et al (1966) under conditions where solubilities were extremely high, but has not been observed otherwise to our knowledge.…”

“…Because H 2 would be of great interest to geomicrobiologists, an experimental search for this product should be conducted. Among those who have studied As 2 S 3 solubility, Weissberg et al (1966) seem to be unique in observing a realgar (AsS) residue, which is the most likely redox complement in As 2 S 3 -bearing systems. A reason why realgar has not been more generally observed might be that significant amounts of AsS component have been concealed within amorphous As 2 S 3 phases in the form of S vacancies (stoichiometrically, As 2 S 3 À S = 2AsS).…”

A spectrophotometric study of the formation and deprotonation of thioarsenite species in aqueous solution at 22°C

“…As 2 S 3 ) in sulfide solutions as a function of pH and at ambient and elevated temperature, the latter variable being important in the transport and precipitation chemistry in hydrothermal ore depositing systems (e.g. Hö ltje, 1929;Babko and Lisetskaya, 1956;Srivastava and Ghosh, 1958;Weissberg et al, 1966;Ivakin et al, 1979a;Mironova and Zotov, 1980;Mironova et al, 1983Mironova et al, , 1990Webster, 1990;Eary, 1992;Clarke and Helz, 2000). A diversity of different thioarsenite stoichiometries (Table 1) were proposed.…”

Speciation of arsenic in sulfidic waters

“…[1][2][3][4] Historically, the formation of soluble thioarsenic species has been recognized as an important factor governing arsenic chemistry in reducing environments. [5][6][7][8][9][10][11][12][13][14][15][16][17] This observation has been paralleled by efforts to identify and quantify the chemistry controlling the formation of thioarsenic species in nature, yet reliable analytical strategies for these species are not fully developed. 18 Speciation models derived from thermodynamic analysis of arsenic sulfide solubility in aqueous systems support the existence of thioarsenite species, 9,[12][13][14][15] as do more recent molecular orbital theory calculations and Raman spectroscopic data.…”