On the oriented transformation of Ca(OH)<sub>2</sub> to CaO

Datta, N.; Chatterji, S.; Jeffery, J. W.; Mackay, Alan L.

doi:10.1180/minmag.1969.037.286.14

Cited by 12 publications

(9 citation statements)

References 3 publications

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“…This structure is also common in other minerals, as brittle micas which are built up of alternate mica-and brucite-like layers [16]. The dehydration shows some common patterns of behaviour as the dehydroxylation processes of simple hydroxides (Mg(OH) 2 , Ca(OH) 2 [17].…”

Section: Introductionmentioning

confidence: 81%

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

Gomez-Villalba

Sierra-Fernández

Rabanal

et al. 2016

Ceramics International

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The dehydration process from Mg 0.97 Ca 0.03 (OH) 2 nanoparticles (brucite type hexagonal structure) to Mg 0.97 Ca 0.03 O (periclase type cubic structure) was studied by Transmission Electron Microscopy (TEM-HRTEM), Electron Diffraction (SAED), Electron Energy Loss Spectroscopy (EELS) and image analysis. The transformation process was monitored in function of the reaction time applying 200 and 300 KV. Changes in porosity were possible to observe only during the irradiation with 200 KV. Depending on the irradiation time, the changes were gradual, producing an increase from the particle's edge towards the inner region. Different stages were observed, corresponding to the amount of water extracted from the particle, until finally a decrease in porosity and particle shrinkage occurs, coinciding with the formation of the Mg-Ca oxide. However, when samples were exposed to 300 KV, the dehydration process was much faster, and the pores structure was destroyed in a shorter time in comparison with lower doses of radiation. High resolution electron microscopy (HRTEM) applying 300 kV allowed identifying the progressive changes from brucite to periclase, including the formation of an intermediate dehydrated phase. The transformation along [0001] brucite and [¯] 1010 brucite orientations was monitored determining differences in the kinetic of reaction related to the presence of point defects affecting the atomic lattice.

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Section: Introductionmentioning

confidence: 81%

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

Gomez-Villalba

Sierra-Fernández

Rabanal

et al. 2016

Ceramics International

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“…Interestingly, the observed orientation relationships are similar to those reported for the dehydroxylation of portlandite. 15 The latter suggests that despite the contrasting energetics (exo-vs endothermal) and large molar volume differences between portlandite and lime, the reversible reaction CaO + H 2 O = Ca(OH) 2 follows the same mechanistic pathway (topotaxy) in both directions.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

The Mechanism of Vapor Phase Hydration of Calcium Oxide: Implications for CO₂capture

Kudłacz

Rodríguez-Navarro

2014

Environ. Sci. Technol.

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Lime-based sorbents are used for fuel- and flue-gas capture, thereby representing an economic and effective way to reduce CO2 emissions. Their use involves cyclic carbonation/calcination which results in a significant conversion reduction with increasing number of cycles. To reactivate spent CaO, vapor phase hydration is typically performed. However, little is known about the ultimate mechanism of such a hydration process. Here, we show that the vapor phase hydration of CaO formed after calcination of calcite (CaCO3) single crystals is a pseudomorphic, topotactic process, which progresses via an intermediate disordered phase prior to the final formation of oriented Ca(OH)2 nanocrystals. The strong structural control during this solid-state phase transition implies that the microstructural features of the CaO parent phase predetermine the final structural and physicochemical (reactivity and attrition) features of the product hydroxide. The higher molar volume of the product can create an impervious shell around unreacted CaO, thereby limiting the efficiency of the reactivation process. However, in the case of compact, sintered CaO structures, volume expansion cannot be accommodated in the reduced pore volume, and stress generation leads to pervasive cracking. This favors complete hydration but also detrimental attrition. Implications of these results in carbon capture and storage (CCS) are discussed.

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“…After 1 and 7 days of incubation, the medium was removed, and the cells were washed with phosphate buffered saline (PBS) and then fixed with 3% glutaraldehyde in PBS for 15 minutes. After fixation, the cells were washed with PBS and dehydrated with graded ethanol-water solution series (30,50,70,80, 90 and 100%) and hexamethyldisilazane (HMDS). The experiments were achieved in duplicates for each group.…”

Section: In Vitro Cytotoxicity Evaluationmentioning

confidence: 99%

“…Calcium borate formation can be explained according to the following reactions (Eq. 6a-c) [28][29][30][31]:…”

Section: Structural Analysismentioning

confidence: 99%

Impact of B2O3 and La2O3 addition on structural, mechanical and biological properties of hydroxyapatite

Khoshsima

Alshemary

Tezcaner

et al. 2018

PAC

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In this study, hydroxyapatite-B 2 O 3-La 2 O 3 composites (with ≤ 20 wt.% B 2 O 3 and ≤ 2 wt.% La 2 O 3) were synthesized via wet precipitation method and calcined at 1100°C for 1 h. X-ray diffraction (XRD) analysis revealed the existence of the pure hydroxyapatite (HA) phase with high crystallinity. Characteristic absorption bands of HA were also observed in Fourier transform infrared spectra. Furthermore, scanning electron microscopy images demonstrated that the addition of B 2 O 3 and La 2 O 3 into HA enhanced the particle growth. Mechanical properties of the composites were studied by diametral tensile test and the results showed that incorporation of 10 wt.% B 2 O 3 and 2 wt.% La 2 O 3 led to a 39% increase in tensile strength (compared to the pure HA). In vitro cytocompatibility of HA-B 2 O 3-La 2 O 3 composites was investigated using Osteosarcoma Cell Lines (Saos-2). Incorporation of B 2 O 3 and La 2 O 3 into HA had no toxic effect towards the cells. Based on its tensile strength properties and biological response, composite of 88 wt.% HA, 10 wt.% B 2 O 3 and 2 wt.% La 2 O 3 was suggested as a promising composite for bone tissue engineering applications.

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On the oriented transformation of Ca(OH)₂ to CaO

Cited by 12 publications

References 3 publications

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

The Mechanism of Vapor Phase Hydration of Calcium Oxide: Implications for CO₂capture

Impact of B2O3 and La2O3 addition on structural, mechanical and biological properties of hydroxyapatite

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On the oriented transformation of Ca(OH)2 to CaO

Cited by 12 publications

References 3 publications

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

TEM-HRTEM study on the dehydration process of nanostructured Mg–Ca hydroxide into Mg–Ca oxide

The Mechanism of Vapor Phase Hydration of Calcium Oxide: Implications for CO2capture

Impact of B2O3 and La2O3 addition on structural, mechanical and biological properties of hydroxyapatite

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On the oriented transformation of Ca(OH)₂ to CaO

The Mechanism of Vapor Phase Hydration of Calcium Oxide: Implications for CO₂capture