engleski

Magnesium decreases the electrical double layer (EDL) forces between carbonate particles

Carbonates are the most widespread minerals and dominate sediments and sedimentary rocks in the Earth's crust. Understanding of carbonate nucleation, growth, stability, and dynamics remain a challenge due to many possible and often concurrent transformation pathways. Experimental insight into the significance of the electrical double layer forces in complex solutions during the carbonate nucleation process is limited - especially in complex solutions with several interfering, coprecipitating, and adsorbing ions. In our work, we show how the electrical double layer formed at the interface between carbonate and electrolyte in the presence of Mg2+ changes in time by using time-resolved electrophoresis and potentiometric measurements. The presence of Mg2+ ions not only stabilizes metastable carbonate phases – like vaterite – but also reduces the magnitude of the repulsive EDL - forces. The first effect has been previously observed and it is usually attributed to the large dehydration energy barrier for Mg2+ ions, the second one has not been studied yet. Our results suggest that the role of the additives on carbonate nucleation pathways is more complex than previously anticipated. Mg2+ can affect not only the carbonate nucleation pathways, but also sediment stability via the additional screening of the long-range electrostatic forces.

magnesium ; electrical double layer (EDL) ; carbonate particles ; time-resolved electrophoresis ; potentiometric measurements ; carbonate nucleation ; carbonate growth ; carbonate stability

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