Effect of pH, CO2, and Organic Ligand on the Kinetics of Talc and Lizardite Dissolution

Abstract

Natural Mg phyllosilicates are potential sources of divalent cations, which are necessary for the mineralization of CO₂ into carbonates. The influence of inorganic (\({\text{HCO}}_{3}^{ - }\)) and organic (oxalate and citrate) ligands on the dissolution kinetics of talc and serpentine was studied in experiments in a flow-through reactor at 25°C. The dissolution rates of natural silicates r (mol cm^–2 s^–1) in solutions of various composition were calculated at the stationary stage of dissolution after a rapid initial stage, which is characterized by the formation of a surface leached layer depleted in magnesium. The presence of ligands increases the dissolution rate of magnesium silicates due to the formation of surface complexes, which leads to magnesium separation from the surface and transfer into solution. The initial incongruent stage may be the most promising for the development of carbonation technologies, because the minimum removal of the network-forming elements prevents the undesirable formation of secondary minerals (for example, clays), which exclude divalent cations from the carbonation process and greatly reduce the permeability of rocks.