The calculation of the solubility of metal hydroxides, oxide-hydroxides, and oxides, and their visualisation in logarithmic diagrams

Abstract

The aim of this text is to show how the solubility (S) of metal hydroxides, oxide-hydroxides, and oxides can be calculated as function of the equilibrium pH of the solutions, taking into account the formation of various cationic and anionic species of metal aqua ions; however excluding all foreign ligands. The plots of log S versus pH are constructed and their applications to treat separations by consecutive precipitation are discussed.

Mobilization of Geochemical Elements to Surface Water in the Active Layer of Permafrost in the Russian Arctic

“…The Mn concentrations were found to be highest in the oxidizing zones in the solid phase, whereas other elements (Ca, Mg, Al, Ti, and Fe) increased in the reduced zones. In both the MU and SY sites, Mn concentrations were found to be higher in the top layer of the soil, which is consistent with the low solubility of Mn in lower pH soils (pH = 4.7 for Mu and 4.8 for Sy) (Scholz & Kahlert, 2015). We speculate that this was because of a more integral gleyed layer (∼10-40 cm) caused by cryoturbation, which could result in a shared origin for the different soils.…”

Comparison of nano-structured transition metal modified tri-metal MgMAl–LDHs (M = Fe, Zn, Cu, Ni, Co) prepared using co-precipitation

“…The synthesis pH was specically chosen to be higher than the optimum/frequently chosen synthesis pH for hydrotalcite synthesis (pH ¼ 10) 38 so that all metal species are kept well above their theoretical hydroxide formation limit. 3,39 Further, the precipitation was carried out at high supersaturation to limit the formation of the hydroxides. The resulting slurry was stirred vigorously at 500 rpm throughout the reaction.…”

Influence of pH tuning at the precursor-preparation process on the structural characteristics and catalytic performance of hydrothermally synthesized ZnAl2O4 nanoparticles

“…This may be related to the appearance of trace ZnO impurities for these samples, as previously shown in Figure 5. Considering the preparation process of the pH-controlled source solutions in this study, the in solution is considered to be higher than that of Al 3+ , because the solubility product of Zn 2+ is much larger than that of Al 3+ [16]. Thus, the overall composition of the precipitate seems to become aluminum-rich rather than stoichiometric after centrifugation.…”