{"title":"羟基磷闪石-羟基磷灰石固溶体[(PbxCa1−x)5(PO4)3OH]在25℃和pH 2-9条件下的表征、溶解和溶解度","authors":"Yinian Zhu, Bin Huang, Zongqiang Zhu, Huili Liu, Yanhua Huang, Xin Zhao, Meina Liang","doi":"10.1186/s12932-016-0034-8","DOIUrl":null,"url":null,"abstract":"<p>The interaction between Ca-HAP and Pb<sup>2+</sup> solution can result in the formation of a hydroxyapatite–hydroxypyromorphite solid solution [(Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(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 (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH), predominantly its thermodynamic solubility and stability in aqueous solution. Nevertheless, no experiment on the dissolution and related thermodynamic data has been reported.</p><p>Dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)] in aqueous solution at 25?°C was experimentally studied. The aqueous concentrations were greatly affected by the Pb/(Pb?+?Ca) molar ratios (X<sub>Pb</sub>) of the solids. For the solids with high X<sub>Pb</sub> [(Pb<sub>0.89</sub>Ca<sub>0.11</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH], the aqueous Pb<sup>2+</sup> 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 X<sub>Pb</sub> (0.00–0.80), the aqueous Pb<sup>2+</sup> 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.</p><p>The dissolution process of the solids with high X<sub>Pb</sub> (0.89–1.00) was different from that of the solids with low X<sub>Pb</sub> (0.00–0.80). The average <i>K</i>\n <sub>sp</sub> values were estimated to be 10<sup>?80.77±0.20</sup> (10<sup>?80.57</sup>–10<sup>?80.96</sup>) for hydroxypyromorphite [Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH] and 10<sup>?58.38±0.07</sup> (10<sup>?58.31</sup>–10<sup>?58.46</sup>) for calcium hydroxyapatite [Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH]. The Gibbs free energies of formation (Δ<i>G</i>\n <span>\n <sup><i>o</i></sup><sub>\n <i>f</i>\n </sub>\n \n </span>) were determined to be ?3796.71 and ?6314.63?kJ/mol, respectively. The solubility decreased with the increasing Pb/(Pb?+?Ca) molar ratios (X<sub>Pb</sub>) of (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(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 (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH) dissolved stoichiometrically at the early stage of dissolution and moved gradually up to the Lippmann <i>solutus</i> curve and the saturation curve for Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH, and then the data points moved along the Lippmann <i>solutus</i> curve from right to left. The Pb-rich (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH) was in equilibrium with the Ca-rich aqueous solution.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"17 1","pages":""},"PeriodicalIF":0.9000,"publicationDate":"2016-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-016-0034-8","citationCount":"36","resultStr":"{\"title\":\"Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9\",\"authors\":\"Yinian Zhu, Bin Huang, Zongqiang Zhu, Huili Liu, Yanhua Huang, Xin Zhao, Meina Liang\",\"doi\":\"10.1186/s12932-016-0034-8\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The interaction between Ca-HAP and Pb<sup>2+</sup> solution can result in the formation of a hydroxyapatite–hydroxypyromorphite solid solution [(Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(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 (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH), predominantly its thermodynamic solubility and stability in aqueous solution. Nevertheless, no experiment on the dissolution and related thermodynamic data has been reported.</p><p>Dissolution of the hydroxypyromorphite–hydroxyapatite solid solution [(Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)] in aqueous solution at 25?°C was experimentally studied. The aqueous concentrations were greatly affected by the Pb/(Pb?+?Ca) molar ratios (X<sub>Pb</sub>) of the solids. For the solids with high X<sub>Pb</sub> [(Pb<sub>0.89</sub>Ca<sub>0.11</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH], the aqueous Pb<sup>2+</sup> 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 X<sub>Pb</sub> (0.00–0.80), the aqueous Pb<sup>2+</sup> 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.</p><p>The dissolution process of the solids with high X<sub>Pb</sub> (0.89–1.00) was different from that of the solids with low X<sub>Pb</sub> (0.00–0.80). The average <i>K</i>\\n <sub>sp</sub> values were estimated to be 10<sup>?80.77±0.20</sup> (10<sup>?80.57</sup>–10<sup>?80.96</sup>) for hydroxypyromorphite [Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH] and 10<sup>?58.38±0.07</sup> (10<sup>?58.31</sup>–10<sup>?58.46</sup>) for calcium hydroxyapatite [Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH]. The Gibbs free energies of formation (Δ<i>G</i>\\n <span>\\n <sup><i>o</i></sup><sub>\\n <i>f</i>\\n </sub>\\n \\n </span>) were determined to be ?3796.71 and ?6314.63?kJ/mol, respectively. The solubility decreased with the increasing Pb/(Pb?+?Ca) molar ratios (X<sub>Pb</sub>) of (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(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 (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH) dissolved stoichiometrically at the early stage of dissolution and moved gradually up to the Lippmann <i>solutus</i> curve and the saturation curve for Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>OH, and then the data points moved along the Lippmann <i>solutus</i> curve from right to left. The Pb-rich (Pb<sub>x</sub>Ca<sub>1?x</sub>)<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH) was in equilibrium with the Ca-rich aqueous solution.</p>\",\"PeriodicalId\":12694,\"journal\":{\"name\":\"Geochemical Transactions\",\"volume\":\"17 1\",\"pages\":\"\"},\"PeriodicalIF\":0.9000,\"publicationDate\":\"2016-05-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1186/s12932-016-0034-8\",\"citationCount\":\"36\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geochemical Transactions\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://link.springer.com/article/10.1186/s12932-016-0034-8\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geochemical Transactions","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1186/s12932-016-0034-8","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9
The 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.
Dissolution 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.
The 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 (ΔGof) 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.
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Geochemical Transactions publishes high-quality research in all areas of chemistry as it relates to materials and processes occurring in terrestrial and extraterrestrial systems.
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