Heterogeneous nucleation and growth mechanism on hydrophilic and hydrophobic surface

Heterogeneous nucleation and nucleation period of calcium carbonate on the mica and the highly oriented pyrolytic graphite (HOPG) substrate have been investigated. Calcium carbonate was prepared by the reaction of calcium nitrate solution with sodium carbonate solution. In the reaction crystallization of calcium carbonate, calcite and vaterite were nucleated on the both substrates. We counted the number of crystalline calcium carbonate on the substrates obtained from various initial supersaturations of calcium carbonate. The number of crystals on the mica surface was much higher than on the HOPG surface. Additionally, the number of crystals on the mica was greatly affected by changing of initial supersaturation. In order to explain the difference between the mica and the HOPG surface, a possible model for the nucleation period of calcium carbonate has been discussed. The surface crystallization on the mica and the HOPG could be described by considering the supersaturation in the bulk solution and in the vicinity of substrate, separately.

Number of CaCO3 crystals onto the substrates under various conditions of initial supersaturationFigure optionsDownload as PowerPoint slideHighlights
► We examine heterogeneous nucleation of CaCO3 on substrates.
► Number of the crystals on the mica is much higher than on the HOPG surface.
► There is an optimum initial supersaturation to generate heterogeneous nuclei.
► We model a nucleation period of CaCO3 near the substrate.
► Surface crystallization with non-equimolar reaction is a realistic production scheme.