Synthesis of aragonite CaCO₃ nanocrystals by reactive crystallization in a high shear mixer

Abstract

Aragonite CaCO 3 nanoparticles were prepared in an in-line high shear mixer (HSM)-aided crystallizer involving the gasliquid-solid (G-L-S) multiphase reactive crystallization between CO 2 gas and the aqueous slurry of Ca(OH) 2 . High crystalline purity aragonite CaCO 3 with the average width of 50 nm and the length/width ratio of 10 were prepared in the HSM-aided crystallizer. Major factors including temperature, CO 2 flow rate and high shear rates had been studied to adjust the polymorph and the morphology of CaCO 3 nanoparticles. The results indicate that the high rotor rates of HSM generate sufficient micro-mixing level in the reactive crystallization, beneficial to the formation of metastable crystal CaCO 3 . Such HSM-aided crystallizer is superior to adjust the micro-mixing environment in the multiphase reactive crystallization, providing a facile pathway to modulate the morphology and crystal growth of metastable crystals.

CO2-Responsive Switchable Solvents to Induce Self-Assembled Crystallization and Phase Control of CaCO3

“…The effect of temperature on the phase transition is also confirmed by the SEM images (Figure a–c for S1*, S2*, and S4*) which indicate that, at elevated temperature, vaterite switching phase does not pass through aragonite metastable phase; rather, it could directly transform to calcite. It is known that aragonite formation is favored at higher temperature , and lower pH; however, in this study, aragonite was formed at lower temperature (40 °C) via vaterite–aragonite phase transition (samples S1*, S5*, S6*). Temperature influences the phase composition; at 50 °C, a mixture of vaterite and calcite was precipitated (sample S2*), whereas, at 60 °C, a calcite–aragonite mixture was obtained (sample S3*).…”

“…Similarly, smaller-sized vaterite microspheres (average diameters of 0.8−5 μm) have demonstrated high loading capacity useful as vaccine adjuvants; 3 and silver nanoparticles (nAg)/vaterite composite was successfully studied for the antibacterial paint development. 5 Aragonite exhibits superior property suitable as a filler material 6 over thermodynamically stable calcite crystals; as such, aragonite was studied to induce B-type carbonate apatite for biomedical applications as a scaffold for bone tissue regeneration. 7 In this context, the fabrication of advanced materials with a diversity of structures or extraordinary properties is essential for the demand of the growing technology which definitely justifies a continuous research interest for the mineralization of CaCO 3 materials; importantly, they are cheap and are fashioned straightforward for better suitability of a selected application.…”

Sintesis Precipitate Calsium Carbonat Sebagai Filler Pada Plastik Ramah Lingkungan

“…Gambar 5. Foto SEM PCC dari batu kapur (a) perbesaran 2.000 x dan (b) perbesaran 7.000 x Gambar 5 menunjukan mikrograf PCC yang diperoleh adalah jenis kristal kalsit [Elfina, 2006] dan aragonite [Kamba et al, 2013;Yang, 2017], dapat dilihat dari bentuknya seperti persegi untuk kristal kalsit dan berbentuk jarum untuk kristal aragonit. Hasil morfologi partikel PCC konsisten dengan pola XRD (Gambar 2).…”

CsCu0.1H2.9PMo11VO40 catalyst synthesized via a high shear mixer facilitated precipitation method for selective oxidation of methacrolein to methacrylic acid

“…33 Additionally, in recent years, the HSM has also been gradually adopted in the field of reactive crystallization. Various materials with specific morphologies (such as MnO 2 nanosheets, 37 nano-CaCO 3 , 38 MgSO 4 ·5Mg(OH) 2 ·3H 2 O whiskers, 39 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 microspheres 40 ) have been successfully synthesized via the HSM-assisted synthetic method. The use of the HSM to produce high-performance catalysts has also been reported.…”