Controlled calcite nucleation on polarized calcite single crystal substrates in the presence of polyacrylic acid

We studied theoretically and experimentally the effects of the surface electric field generated by polarization and polyacrylic acid (PAA) additives on the heterogeneous nucleation of calcite on the calcite single crystal substrates with (10.4), (10.0) and (00.1) orientations. A set of "in-situ...

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Bibliographic Details
Published in:Journal of crystal growth 2015-04, Vol.415, p.7-14
Main Authors: Wada, Norio, Horiuchi, Naohiro, Nakamura, Miho, Nozaki, Kosuke, Hiyama, Tetsuo, Nagai, Akiko, Yamashita, Kimihiro
Format: Article
Language:English
Subjects:
Calcite
Contact
Contact angle
Diffusion
Electric fields
Mathematical analysis
Nucleation
Surface chemistry
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Summary:We studied theoretically and experimentally the effects of the surface electric field generated by polarization and polyacrylic acid (PAA) additives on the heterogeneous nucleation of calcite on the calcite single crystal substrates with (10.4), (10.0) and (00.1) orientations. A set of "in-situ" experiments with optical microscopy was performed to determine the waiting time of CaCO sub(3) nucleation, defined as the time interval between the onset of the diffusion of CO sub(2) and the appearance of the first visible precipitation. Calcite was nucleated on the oriented calcite substrates through diffusion of NH sub(3) and CO sub(2) gas from a solid ammonium carbonate into calcium chloride solutions. A theoretical analysis showed that the surface electric field of the polarized calcite substrate decrease the activation energy for nucleation and consequently promotes nucleation. Experimentally, the surface electric field and PAA addition were found to decrease both contact angles and waiting times, and as a result, promote the heterogeneous nucleation. Combined effect of PAA and surface electric field further reduced contact angles and waiting times regardless of orientation differences of the calcite substrates. The cooperation acts remarkably on N-surface of the respective calcite substrates. The results were explained by the Cassie's equation, a classical heterogeneous nucleation theory under a surface electric field, and matching of the charged sites on the PAA chain with the ion arrangement on the calcite substrate.
ISSN:0022-0248
DOI:10.1016/j.crysgro.2014.12.027