Thermodynamic and Electrochemical Investigation of Pantoprazole: {(RS)-6-(difluoromethoxy)-2- [(3,4-dimethoxypyridin-2-yl)methylsulfinyl]-1H-benzo[d]-imidazole} as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Solution

Abstract

The effect of Pantoprazole on mild steel corrosion in 1. 0M HCl was studied by using weight loss, electrochemical impedance spectroscopy and Tafel polarization measurements. The inhibitor showed maximum inhibition efficiency 97. 78 % at optimum concentration 60 ppm. Potentiodynamic polarization studies suggested that it is a mixed-type inhibitor. Atomic force microscopy observation supported the formation of inhibitor film over the mild steel surface. Adsorption of inhibitor molecules on the mild steel surface in hydrochloric acid obeyed the Langmuir adsorption isotherm. Thermodynamic parameters, value of activation energy (Ea), enthalpy of activation (ΔH&z.ast;), adsorption constant (Kads), enthalpy of adsorption (ΔHads0, entropy of adsorption (ΔSads0) and free energy of adsorption (ΔGads0), were calculated and discussed. © 2012 King Fahd University of Petroleum and Minerals.