Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling
Although vanadinite (Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl) occurs in abundance in various terrestrial geochemical systems of natural and anthropogenic origin and is seriously considered as a potential nuclear waste sequestering agent, its actual applicatio...
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MDPI AG
2021-01-01
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author | Justyna Topolska Bartosz Puzio Olaf Borkiewicz Julia Sordyl Maciej Manecki |
author_facet | Justyna Topolska Bartosz Puzio Olaf Borkiewicz Julia Sordyl Maciej Manecki |
author_sort | Justyna Topolska |
collection | DOAJ |
description | Although vanadinite (Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl) occurs in abundance in various terrestrial geochemical systems of natural and anthropogenic origin and is seriously considered as a potential nuclear waste sequestering agent, its actual application is severely limited by a lack of understanding of its basic thermodynamic parameters. In this regard, the greatest challenge is posed by its incongruent dissolution, which is a pivotal hurdle for effective geochemical modeling. Our paper presents an universal approach for geochemical computing of systems undergoing incongruent dissolution which, along with unique, long-term experiments on vanadinites’ stability, allowed us to determine the mineral solubility constant. The dissolution experiments were carried out at pH = 3.5 for 12 years. Vanadinite has dissolved incongruently, continuously re-precipitating into chervetite (Pb<sub>2</sub>V<sub>2</sub>O<sub>7</sub>) with the two minerals remaining in mutual equilibrium until termination of the experiments. The empirically derived solubility constant K<sub>sp,V,298</sub> = 10<sup>–91.89 ± 0.05</sup> of vanadinite was determined for the first time. The proposed modeling method is versatile and can be adopted to other mineral systems undergoing incongruent dissolution. |
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spelling | doaj.art-cea4a22d59444e95ab11246e014b2b2a2023-12-03T15:12:58ZengMDPI AGMinerals2075-163X2021-01-0111213510.3390/min11020135Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution ModelingJustyna Topolska0Bartosz Puzio1Olaf Borkiewicz2Julia Sordyl3Maciej Manecki4Department of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, PolandDepartment of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, PolandX-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Bldg. 433, Argonne, IL 60439-4858, USADepartment of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, PolandDepartment of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków, PolandAlthough vanadinite (Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl) occurs in abundance in various terrestrial geochemical systems of natural and anthropogenic origin and is seriously considered as a potential nuclear waste sequestering agent, its actual application is severely limited by a lack of understanding of its basic thermodynamic parameters. In this regard, the greatest challenge is posed by its incongruent dissolution, which is a pivotal hurdle for effective geochemical modeling. Our paper presents an universal approach for geochemical computing of systems undergoing incongruent dissolution which, along with unique, long-term experiments on vanadinites’ stability, allowed us to determine the mineral solubility constant. The dissolution experiments were carried out at pH = 3.5 for 12 years. Vanadinite has dissolved incongruently, continuously re-precipitating into chervetite (Pb<sub>2</sub>V<sub>2</sub>O<sub>7</sub>) with the two minerals remaining in mutual equilibrium until termination of the experiments. The empirically derived solubility constant K<sub>sp,V,298</sub> = 10<sup>–91.89 ± 0.05</sup> of vanadinite was determined for the first time. The proposed modeling method is versatile and can be adopted to other mineral systems undergoing incongruent dissolution.https://www.mdpi.com/2075-163X/11/2/135lead apatitechervetitesolubility productdissolution experimentthermodynamicsgeochemical modeling |
spellingShingle | Justyna Topolska Bartosz Puzio Olaf Borkiewicz Julia Sordyl Maciej Manecki Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling Minerals lead apatite chervetite solubility product dissolution experiment thermodynamics geochemical modeling |
title | Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling |
title_full | Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling |
title_fullStr | Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling |
title_full_unstemmed | Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling |
title_short | Solubility Product of Vanadinite Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling |
title_sort | solubility product of vanadinite pb sub 5 sub vo sub 4 sub sub 3 sub cl at 25 °c a comprehensive approach to incongruent dissolution modeling |
topic | lead apatite chervetite solubility product dissolution experiment thermodynamics geochemical modeling |
url | https://www.mdpi.com/2075-163X/11/2/135 |
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