Kinetics of Nesquehonite Nucleation

Author

Halla Rezgui, CUNY City CollegeFollow

Date of Award

2020

Document Type

Thesis

Department

Earth and Atmospheric Sciences

First Advisor

Zhengrong Wang

Keywords

Surface energy, crystal nucleation, induction time, size and shape factors

Abstract

During the nucleation of mineral crystals, the particles (atoms and molecules) will be ordered in a crystal lattice and mineral surfaces will develop. The interfacial energy plays important roles in mineral nucleation. The surface energy can be influenced by many factors including temperature, solution chemistry, ion absorptions, and shape/size of nuclei. Previous research studied the effect of solution stoichiometry on the surface energy between nesquehonite and aqueous solution, which strongly relied on simple assumptions (including shape factors). Our research has sought to provide direct observations and quantify modeling on some of these factors affecting the nucleation of nesquehonite. About 72 nesquehonite nucleation experiments were conducted in aqueous solutions, all of which have been adjusted to similar Mg²⁺/CO₃^2-activity ratios (i.e. log (a Mg²⁺/a CO₃^2-)) ranging between -0.28 and 1.53 but having different saturation states. In these experiments, the induction time is calculated using a new turbidity method, and the induction time correlates with the saturation state which is consistent with the classical nucleation theory (CNT). The calculated surface energy is found to be correlated with log activity ratios, suggesting the control of solution chemistry. In particular, we found that the change of surface energy could be a result of surface energy excess caused by the change in the size and shape factors, as demonstrated by the direct observation using phase-contrast microscopy.

Recommended Citation

Rezgui, Halla, "Kinetics of Nesquehonite Nucleation" (2020). CUNY Academic Works.
https://academicworks.cuny.edu/cc_etds_theses/824