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| DOI | 10.1016/j.epsl.2021.116971 |
| Clay minerals affect calcium (magnesium) carbonate precipitation and aging | |
| Molnár Z.; Pekker P.; Dódony I.; Pósfai M. | |
| 发表日期 | 2021 |
| ISSN | 0012821X |
| 卷号 | 567 |
| 英文摘要 | The effects of pre-existing mineral phases on the nucleation and growth of calcium carbonates from solution are relatively poorly understood, despite the widespread co-occurrence of carbonate minerals with clays and other silicates in rocks, soils, and sediments. Previous studies suggested that sheet silicates template calcite nucleation. Moreover, the presence of certain clay minerals appeared to enhance Mg2+ incorporation, resulting in Mg-bearing calcite or protodolomite. Here, we present the results of titration experiments with an environmentally relevant experimental setup, designed to study the roles of swelling clay minerals in the formation of Mg-bearing CaCO3 phases. We added both Mg-free and Mg-rich calcian solutions to carbonate buffers both in the presence and absence of smectite, and monitored the evolution of the solutions with pH and Ca ion selective electrodes, in order to identify nucleation and phase transition events. Initial products of the titration experiments were aged in their mother solutions for a few months. Both freshly formed and aged materials were studied using a variety of transmission electron microscopy (TEM) techniques. From Mg-free, homogeneous solutions vaterite was the first phase to precipitate. The addition of smectite triggered nucleation at lower supersaturation and generated calcite rather than vaterite. In Mg-rich solutions, aragonite was the first phase to precipitate both without and with clay minerals, and precipitation occurred at similar saturation levels in both samples. In the presence of clays, however, the aragonite nanocrystals were attached to smectite flakes. After the Mg-bearing systems were aged for several months, peculiar assemblages of protodolomite and low-magnesian calcite formed in association with smectite, whereas in the clay-free systems aragonite persisted. These observations suggest that if smectite is present in an environment where carbonates precipitate, the clay mineral has important and complex roles in the formation of Mg-bearing calcium carbonate phases. In addition to enhancing the nucleation of the first carbonate solid, smectite also triggers the formation of calcite-type structures, both at nucleation and in dissolution/reprecipitation reactions during aging. © 2021 The Author(s) |
| 关键词 | carbonate precipitationheterogeneous nucleationMg-bearing calciteMg-carbonate agingprotodolomitesmectite |
| 英文关键词 | Calcium carbonate; Carbonate minerals; Carbonation; Clay minerals; High resolution transmission electron microscopy; Hydration; Ion selective electrodes; Nucleation; Precipitation (chemical); Sediments; Titration; Carbonate precipitation; Heterogeneous nucleation; Magnesium carbonate; Mg-bearing calcite; Mg-carbonate aging; Mineral phase; Nucleation and growth; Protodolomite; Smectites; Vaterite; Calcite; aging; calcite; calcium carbonate; carbonate group; nucleation; precipitation (chemistry); smectite |
| 语种 | 英语 |
| 来源期刊 | Earth and Planetary Science Letters
 |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/203228 |
| 作者单位 | University of Pannonia, Research Institute of Biomolecular and Chemical Engineering, Nanolab, Hungary |
| 推荐引用方式 GB/T 7714 | Molnár Z.,Pekker P.,Dódony I.,et al. Clay minerals affect calcium (magnesium) carbonate precipitation and aging[J],2021,567. |
| APA | Molnár Z.,Pekker P.,Dódony I.,&Pósfai M..(2021).Clay minerals affect calcium (magnesium) carbonate precipitation and aging.Earth and Planetary Science Letters,567. |
| MLA | Molnár Z.,et al."Clay minerals affect calcium (magnesium) carbonate precipitation and aging".Earth and Planetary Science Letters 567(2021). |
| 条目包含的文件 | 条目无相关文件。 | |||||
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