Anion Surfactants as Corrosion Inhibitors for Aluminum Dissolution in HCl Solutions

The role of some surfactants in the corrosion of Al in 1 M HCl has been studied using weight loss and galvanostatic polarization techniques. Results showed that the inhibition occurs through adsorption of the inhibitor molecules on the metal surface. The inhibition efficiency was found to increase with increasing inhibitor concentration and decreased with increasing temperature which is due to the fact, that the rate of corrosion of Al is higher than the rate of adsorption. The adsorption of the these compounds on the metal surface is found to obey Freundlich adsorption isotherm. The inhibiting action of these compounds are considerably enhanced by the addition of KI, due to the increase of the surface coverage and therefore indicate the joint adsorption of these compounds and iodide ions. Thermodynamic parameters for adsorption and activation processes were determined. Galvanostatic polarization data indicated that these compounds act as mixed-type inhibitors. Results obtained from the two techniques are in good agreement.