The abovementioned
physico-chemical factors play an important role in crystal growth on a surface
and hence in the performance over time of membrane materials. An understanding
of the kinetics governing formation and growth of calcium carbonate crystals on
surface is important to gain the ability to predict, control and direct or stop
this process.
Many studies have been performed
of calcium carbonate crystal growth on a macroscopic scale using indirect
methods that monitor changes of solution chemistry. These studies have revealed
a dependence of growth
kinetics upon parameters such as pH, supersaturation ratio, ionic strength
or temperature. Atomic Force Microscopy (AFM) has been extensively used to
study mechanisms and growth rates of single crystals from solution, including
calcite crystals. The high resolution of AFM can visualize monomolecular steps
on atomically flat crystal surfaces. It has been also observed that the AFM tip
can influence the growth rate under supersaturated conditions.
Vertical scanning interferometry is an
alternative approach to study growth rates and morphology of single barite
crystals. In these approaches the mineralization was studied after seeding.
Therefore a measured growth rate is dependent on e.g., seed preparation method.
In another study, cryo-electron tomography was used to investigate
self-nucleated, template controlled growth of CaCO3 crystals from the
solution–phase. Early crystallization events of a few nanometer were observed.
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