engleski

The influence of some naturally occuring minerals on the precipitation of calcium carbonate polymorphs

In this work precipitation of calcium carbonates, initiated by the addtion of suspended mineral particles (quartz, kaolinite or montmorillonite) was investigated. In the precipitation system the initial concentrations of calcium and carbonate species, as well as the ionic strength, were similar to those in seawater. In the model syste, in which no mineral particles were added, vaterite was the only solid phase precipitated after an induction period of approximately two minutes. Quartz had no influence on the precipitation, while the addition of kaolinite to the system partially inhibited the precipitation process ; the effect could probably be attributed to the organic matter desorbed from the surface. In contrast, the addition of calcium montmorillonite, caused an instantaneous precipitation of calcite thus indicating montmorillonite to be a suitable substrate for the overgrowth of this polymorphs.

calcium

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