The apparent activation energy and pre-exponential kinetic factor for heterogeneous calcium carbonate nucleation on quartz

[摘要] Nucleation occurs widely in materials synthesis and natural environments. However, in the nucleation rate equation, values for the apparent activation energy (Ea) and the pre-exponential kinetic factor (A) are thus far unknown because real-time nanoscale observations are difficult to perform. Here we experimentally determine Ea and A using heterogeneous calcium carbonate nucleation on quartz as a model system. Nucleation rates are measured with in situ grazing incidence small-angle X-ray scattering and ex situ atomic force microscopy, and the experiments are conducted with a fixed supersaturation of IAP/Ksp(calc)  = 101.65 at 12, 25, and 31 °C. Ea is calculated as 45 ± 7 kJ mol−1, and A is 1012.0 ± 1.1 nuclei μm−2 min−1, or 102.9 ± 1.3 mol m−2 min−1. Increasing the temperature shortens the induction time, but does not change nucleus sizes. These parameter values are critical for predicting and controlling the nucleation of materials.

[学科分类] 化学工程（综合）