A Green, Simple Chemical Route for the Synthesis of Pure Nanocalcite Crystals

Barhoum, Ahmed; Assche, Guy Van; Makhlouf, Abdel Salam Hamdy; Terryn, Herman; Baert, Kitty; Delplancke, Marie-Paule; El‐Sheikh, Said M.; Rahier, Hubert

doi:10.1021/cg501121t

Cited by 49 publications

(38 citation statements)

References 43 publications

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“…It can be observed from the pattern that the most intense crystalline quartz peak at 2θ = 26.6° (011) belongs to hexagonal structure. The diffraction peaks were in good agreement with the results reported in the literature [39][40][41][42][43]. XRD analysis can be utilized to evaluate particle size and lattice strain due to dislocation or size reduction in the bentonite clay.…”

Section: Williamson-hall (W-h) Size Analysissupporting

confidence: 88%

Nano-structured natural bentonite clay coated by polyvinyl alcohol polymer for gamma rays attenuation

et al. 2019

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The main goal of this work is to find natural rock materials that can be used as effective gamma rays shielding at minimal cost, reliability and wide applications. It must be at particular weight and volume (lighter and more protection). Natural bentonite clay can be used as shelters from nuclear waste because of its large availability and low cost. Bentonite clay was used in two forms naturally as it is from its ores and in ground phase. Natural bentonite was cut into cylindrical pellets at different thicknesses; also, the other form pressed into cylindrical pellets with different thicknesses and different pressing pressures (50, 100 and 150 bar). The different samples are coated with polyvinyl alcohol polymer to prevent nuclear waste leakage through porosity of clay. Chemical analysis and density are measured for all samples. Bentonite clay was found naturally in nanometer scale because it is formed from volcanic ash deposits. The nanoparticle size was determined by dynamic light scattering and Williamson-Hall size analysis using XRD patterns and the help of X-powder program. The particle size of natural bentonite was found to be 59.79 nm. The microstructure was characterized by scanning electron microscope and transmission electron microscopy. The linear and mass attenuation coefficients of nano-structured bentonite clay (natural and pressed) were determined at 662 keV energy of 137 Cs; at 1173 and 1332 keV energies of 60 Co, gamma ray sources were determined by using NaI(Tl) scintillation detector. The experimental results showed that the ground bentonite pressed at 150 bar gave the highest linear and mass attenuation coefficients than other samples. The theoretical and the experimental calculations of mass attenuation coefficient were found to be in a good agreement.

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Section: Williamson-hall (W-h) Size Analysissupporting

confidence: 88%

Nano-structured natural bentonite clay coated by polyvinyl alcohol polymer for gamma rays attenuation

et al. 2019

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“…5a). All CaCO 3 samples showed four single peaks approximately around 1086, 712, 281, and 155 cm -1 , indicating calcite [28,29]. The Raman spectra did not show any signal for the surfactants.…”

Section: Surface Propertiesmentioning

confidence: 88%

Roles of in situ surface modification in controlling the growth and crystallization of CaCO3 nanoparticles, and their dispersion in polymeric materials

et al. 2015

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The in situ surface modification of inorganic nanoparticles (NPs) and its influence on the size, morphology, and particle surface properties is increasingly receiving attention. Control of the size and morphology and perfect dispersion of inorganic NPs in polymer matrices fabricates soft materials with unique optical, electrical, magnetic, gas barrier, self-healing, and thermal and mechanical properties. This study explores the strategy of the in situ modification of inorganic NPs (CaCO 3 ) with cationic and anionic surfactants and the role of in situ modification on the dispersion of these NPs in thermoplastic polymers (poly e-caprolactone, PCL). The surfactants having an appropriate polar head with a high charge density bind onto the crystal's nuclei, protect them against extensive aggregation, and consequently control the size, morphology, and surface properties of the produced NPs. This permits formulation of hybrid materials with enhanced thermal stability and tensile modulus and with a marked increase of the crystallization rate.

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“…The maximum rate of calcite formation is observed at ca. As reported in [11], an increase in the CO 2 flow rate was considered to be responsible for the acceleration of the nucleation rate which, consequently, led to shorter reaction (growth) time thereby leading to nanocrystals rather than microparticles. Besides the pH value, also high concentration of calcium ions favored the formation of calcite.…”

Section: Introductionmentioning

confidence: 82%

“…Moreover, an intermediate aragonite phase with needlelike shape can also be stabilized depending on the process conditions. In particular, the rate of CaO and CO 2 conversion into ions as well as the Ca 2+ /CO 3 2ratio was considered [11] to affect the growth rate of the crystal faces {104} and {211} in a different way, thus leading to calcite crystals with different morphology. pH 8.6 [4], while a lower pH value resulted in the formation of valerite.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Nano‐Calcium Carbonate: The Influence of Process Parameters

Aldea

Snåre

Eränen

et al. 2016

Chemie Ingenieur Technik

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Precipitated calcium carbonate was synthesized by carbonation of calcium hydroxide in the presence and absence of ultrasound (conventional stirring) at atmospheric as well as at elevated pressures and different initial concentrations of Ca(OH) 2 . Spherical morphology of the formed calcite was favored at high Ca(OH) 2 concentrations and low CO 2 pressures. The presence of ultrasound did not show any influence on the reaction rate in case of efficient mixing. A small increase of the reaction rate was observed at lower CO 2 pressures. Elevated pressures in combination with ultrasound did not lead to notable changes of reaction rate or particle morphology.

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A Green, Simple Chemical Route for the Synthesis of Pure Nanocalcite Crystals

Cited by 49 publications

References 43 publications

Nano-structured natural bentonite clay coated by polyvinyl alcohol polymer for gamma rays attenuation

Nano-structured natural bentonite clay coated by polyvinyl alcohol polymer for gamma rays attenuation

Roles of in situ surface modification in controlling the growth and crystallization of CaCO3 nanoparticles, and their dispersion in polymeric materials

Crystallization of Nano‐Calcium Carbonate: The Influence of Process Parameters

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