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

Aragonite CaCO 3 nanoparticles were prepared in an in‐line high shear mixer (HSM)‐aided crystallizer involving the gas‐liquid‐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.