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

• Published in: Communications chemistry Vol. 1; no. 1
• Main Authors: Li, Qingyun, Jun, Young-Shin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 19.09.2018
• Subjects: Activation energy; Atomic force microscopy; Calcium carbonate; Nucleation; Predictive control; Process parameters; Quartz; Small angle X ray scattering; Supersaturation
• ISSN: 2399-3669; 2399-3669
• DOI: 10.1038/s42004-018-0056-5

Abstract Nucleation occurs widely in materials synthesis and natural environments. However, in the nucleation rate equation, values for the apparent activation energy ( E a ) and the pre-exponential kinetic factor ( A ) are thus far unknown because real-time nanoscale observations are difficult to perform. Here we experimentally determine E a 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/ K sp (calc)  = 10 1.65 at 12, 25, and 31 °C. E a is calculated as 45 ± 7 kJ mol −1 , and A is 10 12.0 ± 1.1 nuclei μm −2  min −1 , or 10 2.9 ± 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.