Document Type


Subject Area(s)

Chemical Engineering


A first principle mathematical model of the formation of calcareous deposits on a cathodically protected steel rotatingdisk electrode in seawater is presented. The model includes equations which transport phenomena, electrochemical reactions,precipitation reactions, and a homogeneous reaction involved in the formation of calcareous deposits on an electrodesurface. Predicted concentration profiles show that a high concentration of OH ions on the electrode surface leads to the formation of calcareous deposits. The calcareous deposits contain mostly CaCO3, but the initial deposits are predicted to contain more Mg(OH)2 than CaCO3. The predicted calcareous deposits on the electrode surface reduce the active surface area available for the electrochemical reactions, which results in a decrease in the cathodic current density. The predicted current density as a function of time during the formation of deposits agrees qualitatively with experimental data.