Solutions of magnesium bicarbonate have been prepared by leaching magnesium hydroxide and carbonate trihydrate and calcined dolomite suspensions with carbon dioxide at about one atmosphere.
The metastable solutions of magnesium bicarbonate can not be formed from the carbonate but can be only from the existence of the hydroxide suspensions. At the experiment, to form metastable solution is needed the [OH^-] is 0.1 Mol/liter at flow rate of CO₂ about 33 ml/min. and 20-50 ℃.
Absorption mechanism in this system may be represented by the following; the hydroxide ion reacts with dissolved carbon dioxide to give bicarbonate ion. Then metastable solution breaks down by the precipitation of pillar crystalline magnesium carbonate trihydrate by the reaction between bicarbonate and hydroxyl ions at the solid-liquid interface.
As the absorption proceeds, the carbonate is converted to bicarbonate.