CALCITE GROWTH AND INHIBITION

Despite being one of the most common minerals understanding the growth and nucleation of calcite is still a standing frontier.

 

We measured growth rates on calcite spirals to explain the differences in growth rate that are observed on the structurally distinct sites on calcite steps at nonstoichiometric conditions and used process based growth models to interpret the data. We found that none of the existing models were able to explain the experimentally observed behaviour. We subsequently developed a microkinetic model using density functional theory that accurately reproduces calcite growth over a very wide range of published experimental data, solution composition, saturation index, pH, impurities and additives. In addition we demonstrate that polynuclear complexes play a central role in mineral growth at high supersaturation and that a classical complexation model is sufficient to reproduce measured rates.

We used the constant composition method to characterize the inhibitor index by a range of concentrations of Mg, SO4 and MgSO4. The results are applicable to scaling problematics and can be modeled using the microkinetic model.

 

 

 

 

 

 

 

 

 

 

GROWTH SPIRALS-

-role of saturation index,

Ca:CO3 ratio and surface structure

spirals 1.png

PROCESS BASED GROWTH MODELS

-fitting our experimental data poorly

spirals fitting.png

MICROKINETIC MODEL

-satisfactory fit to our experimental data, literature values as well as for additives. 

microkinetic.png

INORGANICALLY INDUCED INHIBITION

-growth inhibition of Mg, SO4 and MgSO4. 

mias.png

© 2019 by Karina K. Sand

karina.sand@gmail.com

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