Effect of Calcium Gluconate Concentration and Hydrodynamic Effect on Mild Steel Corrosion Inhibition in Simulated Cooling Water

The effects of two important factors, namely concentration and hydrodynamics on the inhibition efficiency of calcium gluconate (C12H22CaO14), were investigated using potentiodynamic polarization and electrochemical impedance spectroscopy tests. Results showed that calcium gluconate was capable of inhibiting the corrosion of mild steel in simulated cooling water. The inhibition efficiency of calcium gluconate was increased by increasing its concentration and decreased by increasing water circulation velocity due to the adsorption process, which leads to the formation of a protective layer with a greater charge-transfer resistance on the metal surface. The hydrodynamic effect seems to promote the adsorption of calcium gluconate on the metal surface, which was confirmed by the fitting of the Langmuir adsorption isotherm.