scholarly journals Dissolution, Solubility, and Stability of the Basic Ferric Sulfate-Arsenates [Fe(SO4)x(AsO4)y(OH)z·nH2O] at 25–45°C and pH 2–10

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zongqiang Zhu ◽  
Hongqu Yang ◽  
Jie Liu ◽  
Yinian Zhu ◽  
Shen Tang ◽  
...  
Keyword(s):  
Ferric Sulfate ◽  
Iron Sulfate ◽  
Acidic Environment ◽  
Free Energies ◽  
Crystal Surfaces ◽  
Dissolution Experiment ◽  
Ion Activity ◽  
Initial Ph ◽  
Solubility Products ◽  
Ion Activity Products

Basic ferric sulfate-arsenates [FeSAsOH, Fe(SO4)x(AsO4)y(OH)z·nH2O] were prepared and characterized to study their potential fixation of arsenic in the oxidizing and acidic environment through a dissolution for 330d. The synthetic solids were well-shaped monoclinic prismatic crystals. For the dissolution of the sample FeSAsOH–1 [Fe(SO4)0.27(AsO4)0.73 (OH)0.27·0.26H2O] at 25–45°C and initial pH 2, all constituents preferred to be dissolved in the order of AsO43− > SO42− > Fe3+ in 1–3 h, in the order of SO42− > AsO43− > Fe3+ from 1–3 h to 12–24 h, and finally in the order of SO42− > Fe3+ > AsO43−. The released iron, sulfate, and arsenate existed dominantly as Fe3+/Fe(OH)2+/FeSO4+, HSO4−/SO42−/FeSO4+, and H3AsO40/H2AsO4−, respectively. The higher initial pHs (6 and 10) could obviously inhibit the release of Fe3+ from solid into solution, and the solid components were released in the order of SO42− > AsO43− > Fe3+. The crystal tops were first dissolved, and the crystal surfaces were gradually smoothed/rounded until all edges and corners disappeared. The dissociations were restricted by the Fe-O(H) breakdown in the FeO6 octahedra and obstructed by the OH− and AsO4 tetrahedra outliers; the lowest concentration of the dissolved arsenic was 0.045 mg/L. Based on the dissolution experiment at 25°C and pH 2, the solubility products (Ksp) for the basic ferric sulfate-arsenate [Fe(SO4)0.27(AsO4)0.73 (OH)0.27·0.26H2O], which are equal to the ion activity products (logˍIAP) at equilibrium, were calculated to be -23.04 ± 0.01 with the resulting Gibbs free energies of formation (ΔGfo) of −914.06 ± 0.03 kJ/mol.

scholarly journals Dissolution and Solubility of the (BaxSr1-x)HAsO4·H2O Solid Solution in Aqueous Solution at 25°C and pH 2

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Xuehong Zhang ◽  
Yinian Zhu ◽  
Caichun Wei ◽  
Zongqiang Zhu ◽  
Zongning Li
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Solubility Product ◽  
Enthalpy Of Mixing ◽  
Saturation Curve ◽  
Free Energies ◽  
Batch Experiments ◽  
Dissolution Experiment ◽  
Barium Concentration ◽  
Solubility Products

Six different members of the (BaxSr1-x)HAsO4·H2O solid solution were prepared and characterized, and then dissolution of the synthetic solids was studied at 25°C and pH 2 in a series of batch experiments for 4320 h. With the increase in the Ba/(Ba+Sr) mole fraction of the solids, the aqueous pH decreased and the aqueous barium concentration increased. The aqueous strontium and arsenic concentrations had the highest values atBa/(Ba+Sr)=0.21. The solubility products for BaHAsO4·H2O and SrHAsO4·H2O were calculated to be10-5.52and10-4.62, respectively. The corresponding free energies of formation were determined to be −1543.99±0.18 kJ/mol and −1537.94±0.02 kJ/mol. The solid solution had a minimum solubility product of10-5.61atBa/(Ba+Sr)=0.82. The Guggenheim coefficients were determined to beao=1.55anda1=-4.35. The Lippmann diagram was a typical Lippmann diagram for a nonideal solid solution with a negative enthalpy of mixing. The system shows an “alyotropic” minimum at the aqueousBa/(Ba+Sr)activity fraction of 0.87 where thesolutusandsoliduscurves meet. At the end of the dissolution experiment, the dissolution followed the saturation curve for the pure endmember BaHAsO4·H2O and approached the intersection with the minimum stoichiometric saturation curve on the Lippmann diagram.

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.

Simplified estimates of ion-activity products of calcium oxalate and calcium phosphate in mouse urine

2011 ◽  
Vol 40 (4) ◽  
pp. 285-291 ◽  
Author(s):  
Hans-Göran Tiselius ◽  
Renato Ribeiro Nogueira Ferraz ◽  
Ita Pfeferman Heilberg
Keyword(s):  
Calcium Phosphate ◽  
Calcium Oxalate ◽  
Mouse Urine ◽  
Ion Activity ◽  
Ion Activity Products

The Calculation of Physicochemical Parameters in the Mimetite Dissolving Process

2013 ◽  
Vol 860-863 ◽  
pp. 1035-1039
Author(s):  
Shuang Cao ◽  
Zong Lan Zhang ◽  
Liu Qin Dai ◽  
Yi Nian Zhu ◽  
Zong Qiang Zhu ◽  
...  
Keyword(s):  
Free Energy ◽  
Physicochemical Parameters ◽  
Solubility Product ◽  
Acidic Environment ◽  
Initial Ph ◽  
Increasing Temperature

Solubility of the artificial synthesis Pb(AsO_4 )_3 Cl was studied at different pH and same temperature to get its solubility product Pb(AsO_4 )_3 Cl and formation free energy (∆G_f^0). The results showed that the solubility and stability of Pb(AsO_4 )_3 Cl were related to pH in the same temperature. The solubility of Pb(AsO_4 )_3 Cl was high in acidic environment (initial pH=2) and in initial pH=4,6 conditions its solubility as near as makes no difference. The ∆G_f^0 increased with increasing temperature.

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.

Solubility and Ion Activity Products of Calcium Phosphate Minerals

1999 ◽  
Vol 28 (2) ◽  
pp. 530-536 ◽  
Author(s):  
W. F. Jaynes ◽  
P. A. Moore ◽  
D. M. Miller
Keyword(s):  
Calcium Phosphate ◽  
Ion Activity ◽  
Ion Activity Products

Degree of saturation with respect to CaCO3, CaMg(CO3)2, and CaSO4 for some thermal and mineral springs in the Southern Rocky Mountains, Alberta and British Columbia

1969 ◽  
Vol 6 (6) ◽  
pp. 1421-1430 ◽  
Author(s):  
R. O. van Everdingen
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Hot Springs ◽  
Equilibrium Constants ◽  
Degree Of Saturation ◽  
Effect Of Temperature ◽  
Mineral Springs ◽  
Southern Rocky Mountains ◽  
Ion Activity ◽  
Ion Activity Products

Comparison of ion-activity products and equilibrium constants for solution of CaCO3, CaMg(CO3)2, and CaSO4 indicates that water from Fairmont Hot Springs and Banff Hot Springs, and from thermal springs in British Columbia, on Lussier River, Ram Creek and near Fording Mountain, are super-saturated with respect to CaCO3 and, to a lesser extent, with respect to CaMg(CO3)2. At other springs saturation occurs after water is discharged from the springs. In the case of hot springs this is caused by the rise in pH that accompanies loss of excess CO2 and, to a lesser degree, by evaporation; cooling of the water tends to lower the degree of saturation somewhat. At cold springs, increase in water temperature after discharge increases the degree of saturation. Only near-saturation with respect to CaSO4 is indicated for Miette Hot Springs, Fairmont Hot Springs, and Fording Mountain Springs; precipitation of CaSO4 may occur here owing to evaporation of part of the water; the effect of temperature on the degree of saturation is small.

An ideal solid solution model for calculating solubility of clay minerals

Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 361-373 ◽  
Author(s):  
Y. Tardy ◽  
B. Fritz
Keyword(s):  
Solid Solution ◽  
Clay Minerals ◽  
Chemical Evolution ◽  
Solid Solutions ◽  
Natural Water ◽  
Free Energies ◽  
Natural Clay ◽  
Data Set ◽  
Solubility Products ◽  
End Members

AbstractA method for estimating Gibbs free energies and stabilities of clay minerals is proposed for use with computer programs aimed at calculating the chemical evolution of natural water-rock systems. This is based on (i) a model for ideal solid solutions of a large number of end-member compositions and (ii) a data set of estimated solubility products from 36 end-members. The application of the method to the production of experimental or natural clay stabilities is discussed.

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