Simple, Reproducible Synthesis of Pure Monohydrocalcite with Low Mg Content

Kitajima, Takuma; Fukushi, Keisuke; Yoda, Masahiro; Takeichi, Yasuo; Takahashi, Yoshio

doi:10.3390/min10040346

Cited by 8 publications

(14 citation statements)

References 18 publications

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“…Comparison of the PXRD results of synthesis provided at different temperatures but at the same Mg/Ca ratio and pH (9 and 35; 18 and 38; Table 2) showed, MHC at low temperature becomes more stable than aragonite. This observation in consistency with Kitajima et al (2020), who showed preferable MHC formation at low temperature. Moreover, we can suggest that relative abundance of MHC in Ikka Fjord (e.g., Dahl andBuchardt 2006) andcaves (e.g., Onac 2001) is also due to the low temperature during its formation.…”

Section: Monohydrocalcite Formation Conditionssupporting

confidence: 92%

“…Recent studies (Kitajima et al 2020) based on MHC XANES spectra confirmed that Mg could be structurally incorporated in MHC (Mg/Ca ratio up to 0.4). It was also shown, that MHC synthesized at low temperature (5 ˚C) contains little Mg (Mg/Ca ratio < 0.01) and almost no AMC (Kitajima et al 2020). In contrast, Nishiyama et al (2013) assumed that any Mg content measured in MHC can be due to discrete Mg carbonate phase.…”

Section: Introductionmentioning

confidence: 94%

“…33-38, Table1). Using different temperatures allowed us to compare MHC with relatively low and high amount of AMC(Kitajima et al 2020).…”

mentioning

confidence: 99%

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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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Section: Monohydrocalcite Formation Conditionssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 94%

See 1 more Smart Citation

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Vereshchagin

Frank‐Kamenetskaya

Kuzmina

et al. 2021

American Mineralogist

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“…The precipitates in the biomimetic experiments were also analyzed by SEM at the same conditions. To compare the difference between biotic and chemically synthesized monohydrocalcite (MHC), the MHC was also synthesized in inorganic solution (initial concentrations: 0.03 mol⋅L –1 MgCl 2 , 0.01 mol⋅L –1 CaCl 2 , 0.015 mol mol⋅L –1 Na 2 CO 3 ) according to the published method ( Kitajima et al, 2020 ). Thus, the formation hydrochemical conditions of chemically synthesized MHC were similar to those of the biotic MHC.…”

Section: Methodsmentioning

confidence: 99%

Selective Adsorption of Amino Acids in Crystals of Monohydrocalcite Induced by the Facultative Anaerobic Enterobacter ludwigii SYB1

et al. 2021

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The morphology, crystal structure, and elemental composition of biominerals are commonly different from chemically synthesized minerals, but the reasons for these are not fully understood. A facultative anaerobic bacterium, Enterobacter ludwigii SYB1, is used in experiments to document the hydrochemistry, mineral crystallization, and cell surface characteristics of biomineralization. It was found that carbonate anhydrase and ammonia production were major factors influencing the alkalinity and saturation of the closed biosystem. X-ray diffraction (XRD) spectra showed that calcite, monohydrocalcite (MHC), and dypingite formed in samples with bacterial cells. It was also found that the (222) plane of MHC was the preferred orientation compared to standard data. Scanning transmission electron microscopy (STEM) analysis of cell slices provides direct evidence of concentrated calcium and magnesium ions on the surface of extracellular polymeric substances (EPS). In addition, high-resolution transmission electron microscopy (HRTEM) showed that crystallized nanoparticles were formed within the EPS. Thus, the mechanism of the biomineralization induced by E. ludwigii SYB1 can be divided into three stages: (i) the production of carbonate anhydrase and ammonia increases the alkalinity and saturation state of the milieu, (ii) free calcium and magnesium ions are adsorbed and chelated onto EPS, and (iii) nanominerals crystallize and grow within the EPS. Seventeen kinds of amino acids were identified within both biotic MHC and the EPS of SYB1, while the percentages of glutamic and aspartic acid in MHC increased significantly (p < 0.05). Furthermore, the adsorption energy was calculated for various amino acids on seven diffracted crystal faces, with preferential adsorption demonstrated on (111) and (222) faces. At the same time, the lowest adsorption energy was always that of glutamic and aspartic acid for the same crystal plane. These results suggest that aspartic and glutamic acid always mix preferentially in the crystal lattice of MHC and that differential adsorption of amino acids on crystal planes can lead to their preferred orientation. Moreover, the mixing of amino acids in the mineral structure may also have a certain influence on the mineral lattice dislocations, thus enhancing the thermodynamic characteristics.

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“…Fukushi et al [34] estimated the solid solubility limit of Mg in the MHC of Mg/Ca = 0.06. Recently, Kitajima et al [35] showed that the structural incorporated Mg in MHC can only be detected from the MHC with very low Mg content (Mg/Ca < 0.01), from the X-ray absorption near edge structure analyses. Therefore, the host of Mg in suspension is likely AMC, which cannot be detected by XRD [34][35][36].…”

Section: Mineralogy Of Suspended Mattermentioning

confidence: 99%

In Situ Formation of Monohydrocalcite in Alkaline Saline Lakes of the Valley of Gobi Lakes: Prediction for Mg, Ca, and Total Dissolved Carbonate Concentrations in Enceladus’ Ocean and Alkaline-Carbonate Ocean Worlds

et al. 2020

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The nature of mineral precipitations in terrestrial alkaline soda lakes provides insights into the water chemistry of subsurface oceans on icy bodies in the outer solar system. Saturation analyses of terrestrial alkaline lakes have shown that the solution chemistries of lake waters are generally controlled by the presence of monohydrocalcite (MHC) and amorphous Mg-carbonate (AMC). However, direct observations of the formation of these metastable carbonates in natural alkaline lakes have been limited. This study provides evidence of in situ MHC formation in alkaline lakes, based on the water chemistry and mineralogy of suspended matter in Olgoy, Boon Tsagaan, and Orog Lakes (Valley of Gobi Lakes, Mongolia). The solution chemistries were close to saturation with respect to MHC and AMC, consistent with other alkaline lakes worldwide. Suspended matter was separated by the ultracentrifugation of lake water following freeze-drying. Our results show that MHC is the common mineral phase in the suspended matter. These observations confirm that MHC is the direct authigenic product of evaporation in alkaline lakes. The carbonate fraction in suspended matter from Olgoy Lake has a Mg/Ca ratio of 0.4, suggesting the formation of AMC in association with MHC. Based on the dissolution equilibria of AMC and MHC, we predict the Mg2+, Ca2+, and total dissolved carbonate concentrations in Enceladus’ ocean to be ~1 mmol/kg, ~10 μmol/kg, and 0.06–0.2 mol/kg, respectively, in the presence of AMC and MHC. We propose that the measurements of Mg contents in plumes will be key to constraining the total dissolved carbonate concentrations and chemical affinities of subsurface oceans on Enceladus and other alkaline-carbonate ocean worlds.

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Simple, Reproducible Synthesis of Pure Monohydrocalcite with Low Mg Content

Cited by 8 publications

References 18 publications

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Effect of magnesium on monohydrocalcite formation and unit-cell parameters

Selective Adsorption of Amino Acids in Crystals of Monohydrocalcite Induced by the Facultative Anaerobic Enterobacter ludwigii SYB1

In Situ Formation of Monohydrocalcite in Alkaline Saline Lakes of the Valley of Gobi Lakes: Prediction for Mg, Ca, and Total Dissolved Carbonate Concentrations in Enceladus’ Ocean and Alkaline-Carbonate Ocean Worlds

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