Stability of CaCO3 in Ca(OH)2 solution

• Zeta potential of CaCO3 particles is positive and greater than + 30 mV in Ca(OH)2 solution.
• Ca(OH)2 solution is a natural stabilizing agent for nano-CaCO3 particles.
• Nano-CaCO3 particles can be produced in Ca(OH)2 solution without needing an additive.

The effect of calcium hydroxide (Ca(OH)2) on the stability of calcium carbonate (CaCO3) particles was investigated with respect to the surface potential and particle size. Both CaCO3 and Ca(OH)2 were dissolved in ultrapure water at concentrations up to 100 mM. The solubility limits were about 18 mM for Ca(OH)2 and about 0.13 mM for CaCO3 at 23 °C in water. Dissolution of commercial CaCO3 in 10 mM of Ca(OH)2 solution and dissolution of Ca(OH)2 in 10 mM of CaCO3 slurry were also studied at similar conditions. Conductivity, pH, zeta potential, and average particle sizes were measured for each solution. The morphological characteristics of the particles were analyzed by the SEM images. It was found that the zeta potential of CaCO3 particles was greater than + 30 mV when they were placed in the Ca(OH)2 solution compared to a zeta potential value of − 10 mV in water. It was concluded that the Ca(OH)2 solution is a stabilizer for the CaCO3 particles.

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