Temat: solubility - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Synthesis and solubility of hopeite Zn₃(PO₄)₂·4H₂O
Autorzy:: Bajda, Tomasz
Rogowska, Melania
Pawłowska, Agnieszka
Tematy:: zinc
phosphate
apatite
dissolution
solubility product; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mineralogiczne
Powiązania:: https://bibliotekanauki.pl/articles/46220160.pdf Link otwiera się w nowym oknie
Opis:: Minerals from the phosphate groups are used in environmental engineering as thermodynamically stable vehicles for heavy metals such as zinc. The hopeite Zn₃(PO₄)₂·4H₂O was synthesized and characterized by X-ray diffraction and scanning electron microscopy. The solubility of the hopeite was measured at 25°C. The average solubility product, log K_sp, for the reaction Zn₃(PO₄)₂·4H₂O ⇔ 3Zn²⁺ + 2PO₄ ³⁻ + 4H₂O at 25°C is –35.72 ± 0.03. The free energy of formation, ΔG°f ,298, calculated from this measured solubility product is –3597.4 ± 1.0 kJ mol−1. The immobilization of zinc in the hopeite structure offers the possibility of developing an effective method for removing Zn from wastewater, water and soils.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Synthesis and solubility of brompyromorphite Pb5(PO4)3Br
Autorzy:: Janicka, Urszula
Bajda, Tomasz
Manecki, Maciej
Tematy:: lead
phosphate
apatite
dissolution
brompyromorphite
solubility product; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mineralogiczne
Powiązania:: https://bibliotekanauki.pl/articles/127627.pdf Link otwiera się w nowym oknie
Opis:: The bromide analogue of pyromorphite Pb5(PO4)3Br was synthesized and characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. The solubility of the brompyromorphite was measured at 25°C and pH values of 2.0, 2.6 and 3.2. For the 3 pH measurements, the average solubility product, log KSP, for the reaction Pb5(PO4)3Br 5Pb2+ + 3PO4 3– + Br– at 25ºC is –77.38 ± 0.70. The free energy of formation, Gf,298, calculated from this measured solubility product is –3724.7 ± 4.3 kJ mol−1. These results confirm that brompyromorphite is more soluble than pyromorphite.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Time constraints on experimental studies of lead apatites
Autorzy:: Topolska, Justyna
Bajda, Tomasz
Puzio, Bartosz
Manecki, Maciej
Kozub-Budzyń, Gabriela
Tematy:: pyromorphite
vanadinite
experimental mineralogy
dissolution
solubility synthesis; Pokaż więcej
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2058621.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the results of experimental studies on the synthesis and thermodynamic stability of selected Pb-apatites in terms of criteria determining termination of the experiments. Based on the case study, we indicate difficulties in analysing the obtained experimental data. Time-resolved sampling of precipitate formed during a dropwise synthesis of pyromorphite was performed and the results were compared to the literature data. It has been concluded that the Ostwald ripening time for synthesized solids depends primarily on the chemical composition of the intended Pb-apatite phase. We presented that heterogeneity of precipitate affects its dissolution in terms of repeatability of the results and equilibrating time. A unique 9-year-long experiment on vanadinite stability at a pH range from 2.0-6.0 revealed that among all tested dissolution conditions only the reactions at the pH = 3.5 can perform as the basis for some thermodynamic calculations. It has been concluded that the rate of phase transitions in the Pb-apatites group can be misleading in terms of determining the equilibrium of the system, and the experimental setup designed particularly to provide reliable controls in this aspect should be involved. Means in this respect have been proposed.
Dostawca treści:: Biblioteka Nauki

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