Surfactant-assisted solvo- or hydrothermal fabrication and characterization of high-surface-area porous calcium carbonate with multiple morphologies

Hexagonally crystallized CaCO3 materials with flower-like, belt-like, network-like, coralloid, and hexagonal and rectangular parallelepiped morphologies were selectively fabricated using the surfactant (cetyltrimethylammonium bromide, sodium dodecyl sulfate, poly(N-vinyl-2-pyrrolidone or poly(ethylene glycol) (PEG)) mediated solvo- or hydrothermal strategy with CaO powders as Ca source in an oleic acid (OA)/ethanol, OA/ethylene glycol or water solvent, respectively. The as-obtained materials were characterized by means of the techniques, such as X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, Fourier transform infrared spectroscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, selected-area electron diffraction, and N2 adsorption–desorption measurement. It is shown that the morphology of the CaCO3 product was associated with the nature of surfactant and solvent and solvo- or hydrothermal temperature. The surfactant-free fabricated CaCO3 particles were cube-like in morphology. The rise in solvo- or hydrothermal temperature favored the enhancement in surface area of the CaCO3 product. Among the as-fabricated CaCO3 samples, the one derived hydrothermally with PEG at 240 °C possessed the highest surface area (134 m2/g). Such a high-surface-area wormhole-like mesoporous CaCO3 sample could decompose below 800 °C to mesoporous CaO with high surface area (110 m2/g). This reversible regeneration feature makes the mesoporous calcite useful in gas adsorption and separation as well as catalysis. The possible mechanisms for the multiply morphological CaCO3 formation have also been discussed.

Calcite-type CaCO3 with multiple morphologies and porous structures are selectively fabricated using the surfactant-mediated solvo- or hydrothermal strategy with CaO as Ca source in an organic or aqueous solvent. The high-surface-area (134 m2/g) CaCO3 derived hydrothermally with PEG at 240 °C for 72 h can decompose to mesoporous CaO with a high surface area (110 m2/g) below 800 °C.Figure optionsDownload as PowerPoint slideResearch highlights
► Surfactant-assisted solvo- or hydrothermal method favors the generation of porous CaCO3.
► Surfactant, solvent and solvo- or hydrothermal temperature determine CaCO3 morphology.
► CaCO3 obtained hydrothermally with PEG at 240 °C possesses a high surface area of 134 m2/g.
► Porous CaCO3 can decompose below 800 °C to mesoporous CaO with a high surface area of 110 m2/g.