Calcium carbonate chain-like nanoparticles: Synthesis, structural characterization, and dewaterability

In the present study, we demonstrate a simple technique to synthesize calcium carbonate chain-like nanoparticles with high aspect ratios; we introduced CO2 gas into aqueous slurry of calcium hydroxide (lime milk) with addition of a small amount of lime milk during the reaction. Primary particle structures and agglomeration states of the chain-like particles were analyzed in detail and compared with those of spheroidal particles synthesized by a carbonation reaction without lime milk addition. The technique to fabricate anisotropic nanoparticles will broaden the applications of calcium carbonate. On the other hand, chain-like particles entangled with each other to form larger and fluffier agglomerates with sporadic pores. It was found that the slurry of chain-like particles showed much higher dewaterability (solid-liquid separation efficiency). Several properties of the filtered and dried cakes were investigated to decipher the mechanism of dewaterability. The novel technique to increase dewaterability without using any additives, such as surfactants, may expand the designing of nanoparticle manufacturing processes.