Growth and aggregation of vaterite in seeded‐batch experiments

Andreassen, Jens‐Petter; Hounslow, Michael J.

doi:10.1002/aic.10205

Cited by 74 publications

(63 citation statements)

References 22 publications

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“…This finding is rather astonishing because it is known that, under identical precipitation conditions via the solution reaction, vaterite is obtained only at higher reaction temperatures and much shorter reaction times: 30 versus 10°C and 15 minutes versus 48 hours for vaterite and calcite, respectively. [44][45][46] In addition, the increase in pH due to evolution of ammonia gas from ammonium carbonate may affect the ratio of vaterite to calcite formed. 47 Knowing that vaterite is not the thermodynamically most stable polymorph, we remeasured the reaction product and noticed that after about one year the transition from vaterite to calcite, the most stable calcium carbonate polymorph, took place almost to completeness (cf.…”

Section: This Journal Is © the Royal Society Of Chemistry 2017mentioning

confidence: 99%

Composition inversion to form calcium carbonate mixtures

et al. 2017

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aComposition inversion takes place in equimolar solid mixtures of sodium or ammonium carbonate and calcium chloride with respect to the combination of anions and cations leading to the corresponding chloride and calcite in complete conversion. The transformation takes place spontaneously under a variety of different situations, even in a powdery mixture resting under ambient conditions. Powder X-ray diffraction data and scanning electron microscopy micrographs are presented to describe the course of the reaction and to characterize the reaction products. The incomplete reaction in the interspace between two compressed tablets of pure starting materials leads to an electric potential due to the presence of uncompensated charges.

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Section: This Journal Is © the Royal Society Of Chemistry 2017mentioning

confidence: 99%

Composition inversion to form calcium carbonate mixtures

et al. 2017

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“…The crystallization was finished directly after the calcium ions containing solution was added (0.75 mol/h) or 15 min after the completed addition in the experiment with 102.86 mol/h feed rate, respectively. For the seeded semibatch experiment performed at 0.75 mol/h the initial supersaturation, S 0 , was estimated from the second order growth rate relationship 23 (Eq. 12) assuming that neither crystal nucleation nor aggregation occurs.…”

Section: àmentioning

confidence: 99%

“…23, Eq. 13 which expresses the integrated form for the activation energy, E a , 23,24 and the universal gas constant, R, the growth rate constant, k g , at 30 C was calculated to be 0.56 nm/s.…”

Section: àmentioning

confidence: 99%

Influence of crystallization conditions on crystal morphology and size of CaCO₃ and their effect on pressure filtration

Beck

Andreassen

2011

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).The temperature, supersaturation, seeding procedure, stirring speed and other parameters were varied in crystallization experiments of calcium carbonate performed in aqueous solutions to control size, particle size distribution and morphology of the particles. Particle size information was obtained by focused beam reflectance measurements and the Coulter Counter Multisizer. Crystals of CaCO 3 could be crystallized as spherical polycrystalline particles of the vaterite polymorph, needle-like crystals of aragonite and both cube-like and novel plate-like crystals of calcite. Filtration experiments for calcium carbonate, performed at a constant pressure difference of 2 bar, show that spherical particles with a larger size show better filterability and that spheres with a wider size distribution, as a result of high supersaturation and nucleation, give higher average cake resistance values. Comparing different particle morphologies, plate-like crystals and needle-like crystals show worse filterability than spherical particles and cube-like particles.

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“…[16][17][18] CaCO 3 spheres were also grown in a desiccator via slow diffusion of CO 2 released by the decomposition of (NH 4 ) 2 CO 3 crystals placed at the bottom of the same desiccator, which also contained a glass dish with CaCl 2 solution. 19 Urea (NH 2 CONH 2 ) was used (instead of CO 2 gas bubbling or Na 2 CO 3 , NaHCO 3 , and (NH 4 ) 2 CO 3 additions) to produce CaCO 3 powders.…”

Section: àmentioning

confidence: 99%

Monodisperse Calcium Carbonate Microtablets Forming at 70°C in Prerefrigerated CaCl₂–Gelatin–Urea Solutions

Taş¹

2009

Int J Applied Ceramic Tech

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Calcium carbonate particles with a unique tablet shape were produced by simply aging the prerefrigerated (at 41C for 24 h) CaCl 2 -gelatin-urea solutions at 701C for 24 h in ordinary glass media bottles. Gelatin is known to be the denatured collagen. The thermal decomposition of dissolved urea was exploited to provide the Ca 21 ion and gelatin-containing solutions with aqueous carbonate ions. Monodisperse CaCO 3 microtablets formed in solution had a mean particle size of 472.5 mm. CaCO 3 microtablets were biphasic in nature and comprised of about 93% vaterite and 7% calcite. Identical solutions used without prerefrigeration yielded only trigonal prismatic calcite crystals upon aging at 701C for 24 h. Prerefrigeration of CaCl 2 -gelatin-urea solutions was thus shown to have a remarkable effect on the particle morphology. Samples were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and powder X-ray diffraction.

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Growth and aggregation of vaterite in seeded‐batch experiments

Cited by 74 publications

References 22 publications

Composition inversion to form calcium carbonate mixtures

Composition inversion to form calcium carbonate mixtures

Influence of crystallization conditions on crystal morphology and size of CaCO₃ and their effect on pressure filtration

Monodisperse Calcium Carbonate Microtablets Forming at 70°C in Prerefrigerated CaCl₂–Gelatin–Urea Solutions

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Growth and aggregation of vaterite in seeded‐batch experiments

Cited by 74 publications

References 22 publications

Composition inversion to form calcium carbonate mixtures

Composition inversion to form calcium carbonate mixtures

Influence of crystallization conditions on crystal morphology and size of CaCO3 and their effect on pressure filtration

Monodisperse Calcium Carbonate Microtablets Forming at 70°C in Prerefrigerated CaCl2–Gelatin–Urea Solutions

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Influence of crystallization conditions on crystal morphology and size of CaCO₃ and their effect on pressure filtration

Monodisperse Calcium Carbonate Microtablets Forming at 70°C in Prerefrigerated CaCl₂–Gelatin–Urea Solutions