Steel dissolution in carbonate environments

The electrochemical dissolution of carbon steel exposed to aqueous carbonates stands as one of the main causes for the deterioration of carbon capture, utilisation and storage facilities, pipelines, hydrocarbon refining equipment and reinforced concrete structures. To unlock the full potential of carbon capture applications and ensure the structural integrity of existing chemical processing and civil infrastructure, a thorough understanding of the mechanism of steel dissolution is needed. Here, we leverage advancements in thermodynamic modelling calculations to re-evaluate the stability of the -C-H 2 O system. In combination with electrochemical measurements under controlled hydrodynamic conditions, we show that the electrochemical dissolution in the form of the iron carbonate complex is solely controlled by the pH dependent carbonate equilibrium. The resultant kinetic mechanism is in full agreement with the experimentally obtained dissolution rates and the thermodynamic calculations. We envision the here used methodology to be applied to the dissolution of other metals exposed to a broad range of electrolyte compositions. • The solubility of iron in the -C-H 2 O system is controlled by the formation of and . • The dissolution of steel in aqueous carbonate-containing environments proceeds via the mass-transfer controlled formation of . • Both the bicarbonate ( ) and carbonate ( ) anion catalyse the dissolution process a pH 9.0 to 10.5. • The proposed dissolution mechanism emerges as a consequence of the aquatic chemistry that governs the pH-dependent equilibrium speciation of dissolved iron and carbon dioxide.