Corrosion of iron in aqueous solutions containing a chemical cleaning agent

The use of chelant agents as a cleaning chemicals to remove iron-based deposits is gaining interest. In this study the effect of tannic acid on the corrosion of iron in neutral solutions was studied using polarization curves, polarization resistance and AC impedance techniques at different conditions which include pH, concentration and immersion time. In neutral solutions tannic acid was found to form a protective layer as a result from the reaction between tannic acid and iron ions. The possibility of using some corrosion inhibitors was also studied. The results indicate that thiosemicarbazide with tannic acid improved the protective layer to an extent which depends on the additive concentration, pH and immersion time.