Abstract
The corrosion inhibition of Cucumis sativus peel extract (CSP) on carbon steel in 1 M HCl solution was investigated by potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency from potentiodynamic polarization and impedance measurements were agreement where the maximum inhibition is around 82%. The inhibition efficiency decreased as the temperature increased. The results obtained showed that CSP extract inhibited the corrosion process by a physical adsorption mechanism that followed the Langmuir adsorption isotherm models. The adsorption thermodynamic parameters that were calculated include, free energy of adsorption (Delta G degrees (ads)), activation energy (Ea), enthalpy of adsorption (Delta H degrees (ads)), and entropy of adsorption (Delta S degrees (ads)) revealed that the adsorption process are spontaneous and endothermic. All the results show that the CSP extract can act as an inhibitor against the corrosion of carbon steel in the HCl medium.