Acetylcholine and Rivastigmine as Corrosion Inhibitors of Cu – Sn - Zn – Pb Alloy in Hydrochloric Acid Environment: DFT & Electrochemical Approach

Abstract

The study on the action of Acetylcholine and Rivastigmine as Corrosion Inhibitors of Cu – Sn - Zn – Pb Alloy in Hydrochloric Acid Environment was carried out using density functional theory, electrochemical impedance spectroscopy, Potentiodynamic polarization, Scanning electron microscopy and weight loss. The result revealed that both Acetylcholine and Rivastigmine expired drugs were good inhibitors of Cu – Sn - Zn – Pb Alloy in Hydrochloric Acid Environment. This was confirmed from results of weight loss (99.1 % and 95.0 %), electrochemical impedance spectroscopy (EIS) (92.5 % and 91.8 %), and Potentiodynamic polarization (97.4 % and 87.1 %). Both inhibitors were able to increase the charge transfer resistance and corrosion current densities of the electrical solution and reduce the double layer capacitance of the metal – solution interface. Inhibition was as a result of adsorption of inhibitor molecules on the Cu – Sn - Zn – Pb surface. Thermodynamically, inhibitors showed greater stability on metal surface, spontaneous in the forward direction and reduction in level of disorderliness. Inhibitors demonstrated a mixed type inhibition while physical adsorption mechanism was proposed for the inhibitor – metal interaction. Langmuir adsorption isotherm was obeyed as data fitted adequately to the isotherm and regression coefficient was approximately unity. A monolayer adsorption was deduces.