Transformation process of amorphous magnesium carbonate in aqueous solution

Tanaka, Junya; Kawano, Jun; Nagai, Takaya; Teng, Hualiang

doi:10.2465/jmps.181119b

Cited by 24 publications

(18 citation statements)

References 16 publications

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“…The water content corresponds to the n value in the AMC chemical formula MgCO 3 •xH 2 O. From the weight loss results, it was calculated that AMC20, AMC60, and AMC80 had x values of 2.2, 1.9, and 1.6, respectively, suggesting that the average chemical formula of the AMC samples is approximately MgCO 3 •2H 2 O, which is in good agreement with that of AMC obtained at 15°C 14 . As mentioned below, since there are no substantial structural differences in AMC samples, the variation of water content does not affect the medium-range structural order of AMC.…”

Section: Resultssupporting

confidence: 72%

“…Amorphous magnesium carbonate (AMC), which can be produced by mixing aqueous solutions containing Mg 2+ and CO 3 2− ions 14 , is a precursor of these crystalline magnesium carbonate hydrate materials. At lower temperatures (below approximately 55 °C), AMC crystallizes into nesquehonite by vigorous stirring in an aqueous solution 15,16 , while at higher temperatures (above approximately 55 °C), hydromagnesite forms [16][17][18] .…”

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confidence: 99%

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Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Yamamoto

Kyono

Okada

2021

Sci Rep

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Mineral trapping through the precipitation of carbonate minerals is a potential approach to reduce CO2 accumulation in the atmosphere. The temperature dependence of amorphous magnesium carbonate (AMC), a precursor of crystalline magnesium carbonate hydrates, was investigated using synchrotron X-ray scattering experiments with atomic pair distribution function (PDF) and X-ray absorption fine structure analysis. PDF analysis revealed that there were no substantial structural differences among the AMC samples synthesized at 20, 60, and 80 °C. In addition, the medium-range order of all three AMC samples was very similar to that of hydromagnesite. Stirring in aqueous solution at room temperature caused the AMC sample to hydrate immediately and form a three-dimensional hydrogen-bonding network. Consequently, it crystallized with the long-range structural order of nesquehonite. The Mg K-edge X-ray absorption near-edge structure spectrum of AMC prepared at 20 °C was very similar to that of nesquehonite, implying that the electronic structure and coordination geometry of Mg atoms in AMC synthesized at 20 °C are highly similar to those in nesquehonite. Therefore, the short-range order (coordination environment) around the Mg atoms was slightly modified with temperature, but the medium-range order of AMC remained unchanged between 20 and 80 °C.

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Section: Resultssupporting

confidence: 72%

mentioning

confidence: 99%

Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Yamamoto

Kyono

Okada

2021

Sci Rep

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“…Previously, dypingite along with nesquehonite was successfully synthesised from AMC (e.g., Tanaka et al 2019), but it was rarely reported in assemblage with natural/synthetic MHC (e.g., Dahl and Buchardt 2006). In most works hydromagnesite (e.g., Rodriguez-Blanco et al carbonates (e.g., Nishiyama et al 2013;Fukushi et al 2017) are considered to be the main Mg-phase concomitant to MHC.…”

Section: Monohydrocalcite Formation Conditionsmentioning

confidence: 99%

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Vereshchagin

Frank‐Kamenetskaya

Kuzmina

et al. 2021

American Mineralogist

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Monohydrocalcite (MHC) is hydrated calcium carbonate, which plays an active role in many geological processes, carbonate biomineralization and can be used for fundamental science (as a paleoenvironmental indicator) and industry (for removal of hazardous anions).Despite a great number of works, the conditions preferable for MHC formation / stabilisation and MHC crystal chemical patterns in relation to Mg and H2O are not clarified yet. In the course of current work, we conducted 38 syntheses to obtain information on MHC formation at different Mg/Ca ratios (0-12), pH (~9-12) and temperature (23 and 3 °C). Newly-formed carbonate precipitates were studied by means of X-ray powder diffraction, optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman and Fouriertransform infrared (FTIR) spectroscopies. Phase diagram for MHC, calcite, aragonite and dypingite as a function of pH and Mg concentration in solution at T= 23 °C and Ca/CO3=0.5 was obtained. We demonstrated that MHC could be stable in dry conditions for up to two years and that the time of crystallisation is important for ACC transformation to MHC. Our results on synthetic MHC stability show that the widespread idea that MHC is a short-lived intermediate phase is wrong. For the first time, on the basis of a regular change in the unit cell parameters the possibility of significant incorporation of magnesium in MHC has been proven. According to FTIR data, it is shown to be accompanied by an increase in the water content, which leads to multidirectional change in a and c MHC parameters.

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“…The metastable phase of carbonate (i.e., AMC and MHC) have not been identified in surface materials in previous remote‐sensing studies (e.g., De Sanctis et al., 2016), although the presence of hydrohalite (NaCl·2H 2 O) and its dehydration product (NaCl) have been suggested to be present near the bright spots of Occator Crater of Ceres (De Sanctis, Ammannito, et al., 2020). Similar to hydrated NaCl (e.g., Thomas et al., 2017; Vu et al., 2016), reflectance spectra of MHC and AMC (Coleyshaw et al., 2003; Tanaka et al., 2019) could be useful in the interpretation of observations of fresh surface materials. Given that the metastable carbonates transform into thermodynamically stable carbonates of calcite, magnesite, and dolomite in a certain amount of time after entrapment within ice, the presence of these metastable phases could be used to estimate the timing of eruption.…”

Section: Implications For Subsurface Brine Reservoirs On Icy Bodiesmentioning

confidence: 99%

Field Investigations of Chemical Partitioning and Aqueous Chemistry of Freezing Closed‐Basin Lakes in Mongolia as Analogs of Subsurface Brines on Icy Bodies

et al. 2021

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Transformation process of amorphous magnesium carbonate in aqueous solution

Cited by 24 publications

References 16 publications

Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Temperature dependence of amorphous magnesium carbonate structure studied by PDF and XAFS analyses

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Field Investigations of Chemical Partitioning and Aqueous Chemistry of Freezing Closed‐Basin Lakes in Mongolia as Analogs of Subsurface Brines on Icy Bodies

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