The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy
Calcium phosphate minerals are typically the solubility-limiting phase for phosphate in calcareous soils. Magnesium (Mg), despite being present in high concentrations in calcareous soils, has been largely neglected in the study of formation and stabilization of soil phosphate minerals due to the hig...
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| Format: | Article |
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MDPI AG
2020-01-01
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| Series: | Soil Systems |
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| Online Access: | https://www.mdpi.com/2571-8789/4/1/8 |
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| author | David M. Hilger Jordan G. Hamilton Derek Peak |
| author_facet | David M. Hilger Jordan G. Hamilton Derek Peak |
| author_sort | David M. Hilger |
| collection | DOAJ |
| description | Calcium phosphate minerals are typically the solubility-limiting phase for phosphate in calcareous soils. Magnesium (Mg), despite being present in high concentrations in calcareous soils, has been largely neglected in the study of formation and stabilization of soil phosphate minerals due to the high solubility of pure Mg phosphate phases. In this study, a series of four common calcium and magnesium phosphate minerals, hydroxyapatite/bobierrite and brushite/newberyite were synthesized in the presence of widely varying Mg concentrations to examine the effects of Mg substitution upon the local bonding environment and overall structure of the precipitates. Phosphorus K-edge X-Ray absorption near edge structure (XANES) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) provide insight into the local coordination environment, whereas synchrotron powder X-Ray diffraction (SP-XRD) and transmission electron microscopy (TEM) were used for structural analysis. In acidic to neutral pH, Mg-bearing brushite phases formed over a wide range of Ca:Mg ratios. In neutral to high pH systems, a short-range order amorphous calcium phosphate (ACP) with a local structure analogous with hydroxyapatite precipitated for a wide range of Ca to Mg ratios. It can be inferred that the presence of Mg in soils leads to stabilization of metastable phases: via cation substitution in brushite and via poisoning of crystal growth propagation for hydroxyapatite. |
| first_indexed | 2024-04-13T04:16:20Z |
| format | Article |
| id | doaj.art-319285d9be5a4503923066ef26a32660 |
| institution | Directory Open Access Journal |
| issn | 2571-8789 |
| language | English |
| last_indexed | 2024-04-13T04:16:20Z |
| publishDate | 2020-01-01 |
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| series | Soil Systems |
| spelling | doaj.art-319285d9be5a4503923066ef26a326602022-12-22T03:02:57ZengMDPI AGSoil Systems2571-87892020-01-0141810.3390/soilsystems4010008soilsystems4010008The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational SpectroscopyDavid M. Hilger0Jordan G. Hamilton1Derek Peak2Department of Earth Sciences, University of Waterloo, Waterloo, ON N2L 3G1, CanadaDepartment of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, CanadaDepartment of Soil Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, CanadaCalcium phosphate minerals are typically the solubility-limiting phase for phosphate in calcareous soils. Magnesium (Mg), despite being present in high concentrations in calcareous soils, has been largely neglected in the study of formation and stabilization of soil phosphate minerals due to the high solubility of pure Mg phosphate phases. In this study, a series of four common calcium and magnesium phosphate minerals, hydroxyapatite/bobierrite and brushite/newberyite were synthesized in the presence of widely varying Mg concentrations to examine the effects of Mg substitution upon the local bonding environment and overall structure of the precipitates. Phosphorus K-edge X-Ray absorption near edge structure (XANES) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) provide insight into the local coordination environment, whereas synchrotron powder X-Ray diffraction (SP-XRD) and transmission electron microscopy (TEM) were used for structural analysis. In acidic to neutral pH, Mg-bearing brushite phases formed over a wide range of Ca:Mg ratios. In neutral to high pH systems, a short-range order amorphous calcium phosphate (ACP) with a local structure analogous with hydroxyapatite precipitated for a wide range of Ca to Mg ratios. It can be inferred that the presence of Mg in soils leads to stabilization of metastable phases: via cation substitution in brushite and via poisoning of crystal growth propagation for hydroxyapatite.https://www.mdpi.com/2571-8789/4/1/8phosphatexanesxasexafsspectroscopyspeciationadsorption |
| spellingShingle | David M. Hilger Jordan G. Hamilton Derek Peak The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy Soil Systems phosphate xanes xas exafs spectroscopy speciation adsorption |
| title | The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy |
| title_full | The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy |
| title_fullStr | The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy |
| title_full_unstemmed | The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy |
| title_short | The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy |
| title_sort | influences of magnesium upon calcium phosphate mineral formation and structure as monitored by x ray and vibrational spectroscopy |
| topic | phosphate xanes xas exafs spectroscopy speciation adsorption |
| url | https://www.mdpi.com/2571-8789/4/1/8 |
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