Influence of the Interfacial pH on Electrochemical CaCO3 Precipitation

The influence of the pH at the electrode/solution interface on CaCO 3 precipitation by means of electrochemistry was studied both theoretically and experimentally in pure calcocarbonic aqueous solutions. This interfacial pH was measured at the electrode by using a pH sensor-grid assembly in a submerged impinging cell. A model which takes into account the electrochemical oxygen reduction and the chemical dissociation of hydrogen carbonate and carbonic acid is proposed to calculate the pH at the electrode/ solution interface. It can reproduce the data using values of adjustable parameters obtained from experiments. Hence, the local concentrations of OH - , HCO - 3, CO 2 - 3, Ca 2 + , and the supersaturation coefficient, β, were determined at the electrode. These data were used to interpret CaCO 3 precipitation on a gold electrode.

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