scholarly journals Dissolution and Solubility Product of Cd-Fluorapatite [Cd5(PO4)3F] at pH of 2–9 and 25–45°C

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ju Lin ◽  
Zongqiang Zhu ◽  
Yinian Zhu ◽  
Huili Liu ◽  
Lihao Zhang ◽  
...  
Keyword(s):  
Solubility Product ◽  
Pure Water ◽  
Solution Ph ◽  
Cadmium Ions ◽  
Molar Ratios ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Total Dissolution ◽  
Energy Of Formation

Dissolution of the synthetic cadmium fluorapatite [Cd5(PO4)3F] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution, pure water, and NaOH solution. The characterization results confirmed that the cadmium fluorapatite nanorods used in the experiments showed no obvious variation after dissolution. During the dissolution of Cd5(PO4)3F in HNO3 solution (pH = 2) at 25°C, the fluoride, phosphate, and cadmium ions were rapidly released from solid to solution, and their aqueous concentrations had reached the highest values after dissolution for <1 h, 1440 h, and 2880 h, respectively. After that, the total dissolution rates declined slowly though the solution Cd/P molar ratios increased incessantly from 1.55∼1.67 to 3.18∼3.22. The solubility product for Cd5(PO4)3F (Ksp) was determined to be 10−60.03 (10−59.74∼10−60.46) at 25°C, 10−60.38 (10−60.32∼10−60.48) at 35°C, and 10−60.45 (10−60.33∼10−60.63) at 45°C. Based on the log Ksp values obtained at an initial pH of 2 and 25°C, the Gibbs free energy of formation for Cd5(PO4)3F (ΔGf0) was calculated to be −4065.76 kJ/mol (−4064.11∼−4068.23 kJ/mol). The thermodynamic parameters for the dissolution process were computed to be 342515.78 J/K·mol, −85088.80 J/mol, −1434.91 J/K·mol, and 2339.50 J/K·mol for ΔG0, ΔH0, ΔS0, and ΔCp0, correspondingly.

scholarly journals Dissolution, Stability and Solubility of Tooeleite [Fe6(AsO3)4(SO4)(OH)4·4H2O] at 25–45 °C and pH 2–12

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 921 ◽  
Author(s):  
Zongqiang Zhu ◽  
Jun Zhang ◽  
Yinian Zhu ◽  
Jie Liu ◽  
Shen Tang ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
Solubility Product ◽  
Arsenic Concentration ◽  
Dissolved Iron ◽  
Activity Product ◽  
Free Energy Of Formation ◽  
Ion Activity ◽  
Initial Ph ◽  
Energy Of Formation

Tooeleite [Fe6(AsO3)4(SO4)(OH)4·4H2O] was synthesized and characterized to investigate its possible immobilization for arsenic in acidic and alkali environments by a long-term dissolution of 330 d. The synthetic tooeleite was platy crystallites of ~1μm across, giving the lattice parameters of a = 6.4758 Å, b = 19.3737 Å and c = 8.9170 Å. For the tooeleite dissolution, the dissolved arsenic concentration showed the lowest value of 427.3~435.8 mg/L As at initial pH 12 (final pH 5.54). The constituents were dissolved preferentially in the sequence of SO42− > AsO33− > Fe3+ in the aqueous medium at initial pH 2–12. The dissolved iron, arsenite and sulfate existed mainly as FeSO4+/Fe3+, H3AsO30 and SO42− at initial pH 2, and in the form of Fe(OH)30/Fe(OH)2+, H3AsO30 and SO42− at initial pH 12, respectively. The tooeleite dissolution was characterized by the preferential releases of SO42− anions from solid surface into aqueous medium, which was fundamentally controlled by the Fe-O/OH bond breakages and the outer OH− group layers. From the data of the dissolution at 25 °C and initial pH 2 for 270–330 d, the ion-activity product [logˍIAP], which equaled the solubility product [Ksp] at the dissolution equilibrium, and the Gibbs free energy of formation [ΔGfo] were estimated as −200.28 ± 0.01 and −5180.54 ± 0.07 kJ/mol for the synthetic tooeleite, respectively.

scholarly journals Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yinian Zhu ◽  
Zongqiang Zhu ◽  
Xin Zhao ◽  
Yanpeng Liang ◽  
Yanhua Huang
Keyword(s):  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Ultrapure Water ◽  
Solution Ph ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Water Ph ◽  
Ft Ir ◽  
Sem Analyses

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The averageKspvalues for Pb5(PO4)3OH were determined to be 10−80.77(10−80.57−10−80.96) at 25°C, 10−80.65(10−80.38−10−80.99) at 35°C, and 10−79.96(10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [ΔGfo] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol).

The Characteristic Dissolution and Physical Chemistry Parameter of Synthetic Pyromorphite

2014 ◽  
Vol 887-888 ◽  
pp. 975-978
Author(s):  
Xin Zhao ◽  
Wei Zou ◽  
Zong Lan Zhang ◽  
Zong Qiang Zhu ◽  
Yi Nian Zhu
Keyword(s):  
Free Energy ◽  
Solubility Product ◽  
Apatite Structure ◽  
Batch Experiments ◽  
Batch Dissolution ◽  
Free Energy Of Formation ◽  
The Mean ◽  
The Fourier Transform ◽  
Chemistry Parameter ◽  
Energy Of Formation

The Dissolution of Synthetic Pyromorphite was Studied at 25°C in a Series of Batch Experiments. in Addition, the Aqueous Concentrations from the Batch Dissolution were Used to Calculate the Solubility Product and Free Energy of Formation of Pyromorphite. the Results of the Fourier Transform Infrared Spectroscopy Analyses Indicated that the Synthetic, Microcrystalline Pyromorphite with Apatite Structure Used in the Experiments has Not Changed after Dissolution. the Mean KspValue was Calculated for Pb5(PO4)3Cl of 10-78.31 at 25°C; the Free Energy of Formation ΔGf0[Pb5(PO4)3Cl] was-3756.82kJ/mol.

The Free Energies of Hydration of Gaseous Ions

1948 ◽  
Vol 1 (4) ◽  
pp. 480 ◽  
Author(s):  
NS Hush
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Pure Water ◽  
Free Energies ◽  
The Real ◽  
Free Energy Of Formation ◽  
Energy Of Hydration ◽  
Free Energy Of Hydration ◽  
Molecule Interaction ◽  
Energy Of Formation

Values of hydration energies of individual ions have usually been obtained by division of sums of energies of hydration of pairs of ions, and those calculated by different authors are usually mutually inconsistent. " Experimental " figures, whenever these are quoted, have always been obtained by assuming the truth of theoretical equations whose accuracy has not been independently checked. The distinction between free energy of ion/water-molecule interaction and the real free energy of hydration of a gaseous ion is pointed out, and the importance of Klein and Lange's measurement of the Volta-potential Hg/Hg+ (soln.), which makes possible the direct calculation of real free energies of hydration of individual ions, thus providing a check on theoretical values, is emphasized. Utilizing this value, the equation - ΔFh� = - ΔFf� + ΔFi� + ΔFs�- 103.92 z kcal. (where ΔFs� is the free energy of formation of the gaseous monatomic element, ΔFi� is the free energy of ionization, ΔFf�is the free energy of formation of the aqueous ion, and ΔFh� is the real free energy of hydration of the ion, of valency z, at 298.2� K.) is derived from fundamental considerations. By means of this equation, the real free energies of hydration of 49 ions are calculated, using the most reliable data. It is proposed that these be provisionally accepted as standard values. Several subsidiary values for important ions are calculated indirectly. The difference between ΔFh� and the free energy of ion/water-molecule interaction is discussed in relation to the surface structure of water : a value of -0.30 v. is derived for the X-potential at the surface of pure water, and it is concluded that at the water/gas interface the positive poles of the surface layer are oriented towards the gas phase. The applicability of a modified Born equation in the calculation of free energies of hydration is discussed, and a modified equation is proposed which yields values of ΔFh� for gaseous ions with noble gas structure in excellent agreement with those calculated independently by the method described above.

scholarly journals Synthesis and solubility of brompyromorphite Pb5(PO4)3Br

Mineralogia ◽  
2012 ◽  
Vol 43 (1-2) ◽  
pp. 129-135 ◽  
Author(s):  
Urszula Janicka ◽  
Tomasz Bajda ◽  
Maciej Manecki
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Solubility Product ◽  
X Ray Diffraction ◽  
Ph Measurements ◽  
X Ray ◽  
Ph Values ◽  
Free Energy Of Formation ◽  
Scanning Electron ◽  
Energy Of Formation

AbstractThe 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+ + 3PO- 3- + Br- at 25ºC is -77.38 ± 0.70. The free energy of formation, ΔG°f,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.

Solubility of mimetite Pb5(AsO4)3Cl at 5 - 55°C

2010 ◽  
Vol 7 (3) ◽  
pp. 268 ◽  
Author(s):  
Tomasz Bajda
Keyword(s):  
Solubility Product ◽  
Contaminated Sites ◽  
Background Solution ◽  
Alkaline Ph ◽  
Arsenic Compounds ◽  
Weakly Alkaline ◽  
Hydrochemical Modelling ◽  
Ph Values ◽  
Free Energy Of Formation ◽  
Energy Of Formation

Environmetal context.The mobility of toxic arsenic compounds in the environment can be controlled by the solubility of certain minerals. To predict and model the fate and behaviour of these contaminants, the solubility and related thermodynamic properties of the lead and arsenic mineral mimetite were determined. The data obtained in this study will be used to optimise and increase the effectiveness of remediation procedures that are already applied to contaminated sites. Abstract.The solubility of the synthesised mimetite was measured in a series of dissolution experiments at 5–55°C and at pH values between 2.00 and 2.75. The solubility product logKSP for the reaction Pb5(AsO4)3Cl ↔ 5Pb2+ + 3AsO43– + Cl– at 25°C is –76.35 ± 1.01. The free energy of formation ΔGf,2980 calculated from this measured solubility product equals –2634.3 ± 5.9 kJ mol–1. The temperature dependence of the logKSP is non-linear, indicating that the enthalpy of the reaction depends on the temperature. The enthalpy of the formation of mimetite ΔHf0, is –2965.9 ± 4.7 kJ mol–1, the entropy, ΔS0, is 39.5 J mol–1 K–1, and the heat capacity, ΔCp,f0 is –6172 ± 105 J mol–1 K–1. Hydrochemical modelling indicates that regardless of the composition of the background solution, Pb5(AsO4)3Cl is most stable at neutral to weakly alkaline pH.

scholarly journals Dissolution and Solubility of the Synthetic Natroalunite and the Arsenic-Incorporated Natroalunite at pH of 2.00–5.60 and 25–45°C

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Yinian Zhu ◽  
Huiling Xuan ◽  
Yanpeng Liang ◽  
Qiming Yan ◽  
Zongqiang Zhu ◽  
...  
Keyword(s):  
Environmental Science ◽  
Pure Water ◽  
Thermodynamic Quantities ◽  
Free Energies ◽  
Solution Ph ◽  
Ph Variation ◽  
Initial Ph ◽  
Solubility Products ◽  
Living Organisms ◽  
Arsenic Incorporation

Arsenic is very harmful to most living organisms. The solubility data of As-containing compounds are significant in geoscience and environmental science. The arsenic-incorporated natroalunite precipitation has been proposed to eliminate arsenic from water, both for industrial practice and remediation of polluted areas. Unfortunately, only few works have been made on partial arsenic incorporation in natroalunite and the thermodynamic data for natroalunite and arsenic-incorporated natroalunite now are still lacking. Moreover, the dissolution mechanisms of arsenic-incorporated natroalunites have never been studied. In the present work, the dissolution of the synthetic natroalunite [Na0.93(H3O)0.61Al2.82(SO4)2(OH)6] and the synthetic arsenic-incorporated natroalunite [Na0.88(H3O)2.44Al2.35(AsO4)0.38(SO4)1.62(OH)6] at 25°C, 35°C, and 45°C was experimentally examined in HNO3 solution (pH of 2.00 and 4.00) and pure water. The characterizations confirmed that the solids showed no recognizable change after dissolution. All dissolutions underwent a pH variation, which was caused by a great depleting of H3O+/OH− ions, typically at the reaction beginning. The dissolution in H3O+ medium proved to be near-stoichiometric within the short beginning period, and the dissolved Na+, Al3+, SO42−, and AsO43− concentrations were stoichiometric according to the initial solids and then appeared to be nonstoichiometric with the Na/SO4 mole ratios higher and the Al/SO4 and AsO4/SO4 mole ratios lower than the stoichiometry until the experimental end, indicating that the components were released from solid to solution preferentially after the following order: Na+ (H3O+) > SO42− > AsO43− > Al3+. From the experimental results under the condition of initial pH 2.00 and 25°C, the solubility products [Ksp] and the Gibbs free energies of formation [ΔGf°] were calculated to be 10−81.02±0.33∼10−81.04±0.27 and −4713 ± 2 to −4714 ± 1 kJ/mol for the natroalunite and 10−92.30±0.30∼10−92.41±0.37 and −5078 ± 2 to −5079 ± 2 kJ/mol for the arsenic-incorporated natroalunite, respectively. The thermodynamic quantities, ΔG°, ΔH°, ΔS°, and ΔCp°, were determined to be 462303.43 J/K·mol, 122466.83 J/mol, −1140.39 J/K·mol, and 4280.13 J/K·mol for the natroalunite dissolution reaction at initial pH 2.00 and 25°C and to be 526925.48 J/K·mol, 159674.76 J/mol, −1232.38 J/K·mol, and 1061.12 J/K·mol for the dissolution of the arsenic-incorporated natroalunite at initial pH 2.00 and 25°C, respectively.

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