Silver Solubility in Supercritical Fluids in a Wide Range of NaCl Concentration (0.6–50 wt %)—Experimental and Thermodynamic Descriptionстатья
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Дата последнего поиска статьи во внешних источниках: 15 сентября 2021 г.
Аннотация:The solubility of Agcr has been measured in a 0.1m (mol·(kg H2O)−1) solution of HCl at a fixed hydrogen content (∼0.5m) as a function of NaCl concentration from 0.1 to 18m at temperatures ranging from 425 to 475 °C and pressures of 500 and 1000 bar. It is found that AgCl2– is a dominant species in the whole range of NaCl concentrations (up to 50 wt %). By the treatment of the experimental data, the applicability of the Debye–Hückel and the Setchenov-type equations was tested. The solubility data over the entire NaCl concentration range is accurately (within the experimental uncertainty of 0.1 log m(Ag)) described by the reaction Agcr + HClaq + Cl– = AgCl2– + 0.5 H2aqKs and simple equations for activity coefficients log γi = (Azi2√I)/(1 + åB√I) + Γγ + bγ ·I (for charged species) log γn = Γγ + bn · I (for neutral species) where å = 4.5 Å and bγ = 0 for all charged species, bn = 0 for all neutral species, Γγ = −log(1 + 0.018m*), m* is the sum of the concentrations of all solute species. The values of the Ag solubility constant and log Ks are determined as −0.33 ± 0.03 (425 °C/1000 bar), −0.19 ± 0.02 (450 °C/500 bar), and −0.10 ± 0.04 (475 °C/1000 bar). For the most concentrated solutions (5–18m NaCl), the experimental data description can be slightly improved by accepting the Setchenov parameter bn = 0.05, but the accurate determination of the bn value requires additional experimental studies. It should be noted that this approach was developed for a simple system with a 1:1 background electrolyte, which is free of multi-charged species.