Thermal expansion of solid solutions in apatite binary systems

Knyazev, A. V.; Bulanov, E. N.; Korokin, V. Zh.

doi:10.1016/j.materresbull.2014.09.089

Cited by 10 publications

(5 citation statements)

References 12 publications

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“…Due to the large substitution capacity for various toxic trace elements, the natural or synthetic calcium apatite can be used to immobilize or remove hazardous chemicals in metal-contaminated soils and industrial wastewaters [ 4 , 8 , 11 , 16 – 18 ]. Lead apatite is the most stable lead form under various environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

et al. 2016

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BackgroundThe interaction between Ca-HAP and Pb2+ solution can result in the formation of a hydroxyapatite–hydroxypyromorphite solid solution [(PbxCa1−x)5(PO4)3(OH)], which can greatly affect the transport and distribution of toxic Pb in water, rock and soil. Therefore, it’s necessary to know the physicochemical properties of (PbxCa1−x)5(PO4)3(OH), predominantly its thermodynamic solubility and stability in aqueous solution. Nevertheless, no experiment on the dissolution and related thermodynamic data has been reported.ResultsDissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3(OH)] in aqueous solution at 25 °C was experimentally studied. The aqueous concentrations were greatly affected by the Pb/(Pb + Ca) molar ratios (XPb) of the solids. For the solids with high XPb [(Pb0.89Ca0.11)5(PO4)3OH], the aqueous Pb2+ concentrations increased rapidly with time and reached a peak value after 240–720 h dissolution, and then decreased gradually and reached a stable state after 5040 h dissolution. For the solids with low XPb (0.00–0.80), the aqueous Pb2+ concentrations increased quickly with time and reached a peak value after 1–12 h dissolution, and then decreased gradually and attained a stable state after 720–2160 h dissolution.ConclusionsThe dissolution process of the solids with high XPb (0.89–1.00) was different from that of the solids with low XPb (0.00–0.80). The average Ksp values were estimated to be 10−80.77±0.20 (10−80.57–10−80.96) for hydroxypyromorphite [Pb5(PO4)3OH] and 10−58.38±0.07 (10−58.31–10−58.46) for calcium hydroxyapatite [Ca5(PO4)3OH]. The Gibbs free energies of formation (ΔGfo) were determined to be −3796.71 and −6314.63 kJ/mol, respectively. The solubility decreased with the increasing Pb/(Pb + Ca) molar ratios (XPb) of (PbxCa1‒x)5(PO4)3(OH). For the dissolution at 25 °C with an initial pH of 2.00, the experimental data plotted on the Lippmann diagram showed that the solid solution (PbxCa1−x)5(PO4)3(OH) dissolved stoichiometrically at the early stage of dissolution and moved gradually up to the Lippmann solutus curve and the saturation curve for Pb5(PO4)3OH, and then the data points moved along the Lippmann solutus curve from right to left. The Pb-rich (PbxCa1−x)5(PO4)3(OH) was in equilibrium with the Ca-rich aqueous solution.Graphical abstractLippmann diagrams for dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 ˚C and an initial pH of 2.00.Electronic supplementary materialThe online version of this article (doi:10.1186/s12932-016-0034-8) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

et al. 2016

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“…It is possible, though, that in a larger range of temperatures such tendency would be observed. According to previous studies for Pbapatite, pure pyromorphite shows thermal expansion in the temperature range 298K -1373K (Hovis et al 2015;Knyazev et al 2015;Gu et al 2020). However, there is no similar data for REE-substituted pyromorphite.…”

Section: Methodsmentioning

confidence: 90%

Single-crystal analysis of La-doped pyromorphite [Pb5(PO4)3Cl]

Sordyl,

Rakovan,

Burns

et al. 2023

American Mineralogist

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Rare earth elements (REE) in calcium apatite have been widely described in the literature.Based on the investigations of minerals and their synthetic analogs, the mechanism of substitution of REE 3+ for Ca 2+ and their structural positions are well established. Although the presence of REE in natural pyromorphite has been reported, the structural response of substitution of REE 3+ for Pb 2+ is not established. A better understanding of REE-rich Pb-apatite may facilitate the potential use of this mineral in industrial processes. Two La-doped pyromorphite analogs (Pb5(PO4)3Cl) and two control pyromorphite analogs (with the absence of La) were synthesized from aqueous solutions at 25˚C. Na + and K + were used as charge compensating ions to facilitate the incorporation of trivalent REE cations (La 3+ + Na +  2Pb 2+ and La 3+ + K +  2Pb 2+ ). Microprobe analysis, scanning electron microscopy, and Raman spectroscopy were used to confirm the purity of obtained phases. High precision crystal structure refinements (R1 = 0.0140-0.0225) of all four compounds were performed from singlecrystal X-ray diffraction data. The La content varied from 0.12(1) to 0.19(1) atoms per formula unit with the counter ions of K + and Na + , respectively. Both substituting ions were This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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“…Each dissolution was designed by adding 2.0 g of the synthesized Ca-HA or Zn-Ca-HA to 100 mL of HNO 3 solution (pH = 2) or ultrapure water (pH = 5.6) or NaOH solution (pH = 9) in a series of 150 mL polypropylene bottles, which were then capped and soaked in the water bath of 25 ∘ C. From the bottles, 5 mL of the aqueous solutions was sampled at 23 intervals (1,3,6,12,24,48,72, 120, 240, 480, 720, 1080, 1440, 1800, 2160, 2880, 3600, 4320, 5040, 5760, 7200, 7920, and 8640 hours), filtered through a 0.22-m-pore-size filter and stabilized using 0.2% HNO 3 solution. After each sampling, 5 mL of the corresponding HNO 3 solution, ultrapure water, or NaOH solution was added.…”

Section: Dissolution Experimentsmentioning

confidence: 99%

“…Phosphate apatites form an enormous mineral group due to their huge isomorphic capacity [1,2], which play an important role in many research areas such as biomaterials and environmental science [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…Calcium hydroxylapatite (HA) can also be applied to immobilize dangerous metallic compounds in metal-contaminated soils and industrial wastewaters due to its huge ion substitution capacity, which can considerably decrease the mobility and bioavailability of Zn 2+ , Pb 2+ , Cd 2+ , Cu 2+ , Ni 2+ , and U 2+ by transforming these toxic metal ions into some new forms having low solubility and high geochemical stability [1,5,[14][15][16][17][18]. Heavy metal cations can easily substitute for Ca 2+ in the hydroxylapatite structure and form zinc-calcium hydroxylapatite (Zn-Ca-HA), lead-calcium hydroxylapatite2 Journal of Chemistry understand mineral evolution and natural phenomenon or to optimize the industrial processes concerning apatite [5,19,20].…”

Section: Introductionmentioning

confidence: 99%

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Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(Zn_xCa_1−x)₅(PO₄)₃OH] at 25°C

Zhao

Zhu

et al. 2017

Journal of Chemistry

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A series of Zn-substituted hydroxylapatites [(Zn x Ca 1−x ) 5 (PO 4 ) 3 OH, Zn-Ca-HA] with the Zn/(Zn + Ca) molar ratio ( Zn ) of 0∼0.16 was prepared and characterized, and then the dissolution of the synthesized solids in aqueous solution was investigated by batch experiment. The results indicated that the aqueous zinc, calcium, and phosphate concentrations greatly depended on the Zn/(Zn + Ca) molar ratio of the Zn-Ca-HA solids ( Zn ). For the Zn-Ca-HA dissolution at 25 ∘ C with an initial pH of 2.00, the final solution pH increased, while the final solution calcium and phosphate concentrations decreased with the increasing Zn . The final solution zinc concentrations increased with the increasing Zn when Zn ≤ 0.08 and decreased with the increasing Zn when Zn = 0.08∼0.16. The mean sp values for (Zn x Ca 1−x ) 5 (PO 4 ) 3 OH at 25 ∘ C decreased from 10 −57.75 to 10 −58.59 with the increasing Zn from 0.00 to 0.08 and then increased from 10 -58.59 to 10 -56.63 with the increasing Zn from 0.08 to 0.16. This tendency was consistent with the dependency of the lattice parameter on Zn . The corresponding free energies of formation (Δ ) increased lineally from −6310.45 kJ/mol to −5979.39 kJ/mol with the increasing Zn from 0.00 to 0.16.

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Thermal expansion of solid solutions in apatite binary systems

Cited by 10 publications

References 12 publications

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Single-crystal analysis of La-doped pyromorphite [Pb5(PO4)3Cl]

Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(Zn_xCa_1−x)₅(PO₄)₃OH] at 25°C

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Thermal expansion of solid solutions in apatite binary systems

Cited by 10 publications

References 12 publications

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Single-crystal analysis of La-doped pyromorphite [Pb5(PO4)3Cl]

Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(ZnxCa1−x)5(PO4)3OH] at 25°C

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Characterization, Dissolution, and Solubility of Zn-Substituted Hydroxylapatites [(Zn_xCa_1−x)₅(PO₄)₃OH] at 25°C