Corrosion Inhibition of C38 Steel in Acidic Medium Using N-1 Naphthylethylenediamine Dihydrochloride Monomethanolate

The corrosion inhibition effect of N-1-Naphthylethylenediamine Dihydrochloride Monomethanolate (N-NEDHME) as a new inhibitor was studied using electrochemical polarisation, electrochemical impedance spectroscopy (EIS) measurements and weight loss methods. N-NEDHME revealed good corrosion inhibition efficiency even at low concentrations towards C38 steel in HCl medium. Results showed that this compound acts as a mixed type inhibitor. As the inhibitor concentration increased, the charge transfer resistance of C38 steel increased and double layer capacitance decreased. Data, obtained from EIS measurements, were analyzed to model the corrosion inhibition process through appropriate equivalent circuit model, a constant phase element (CPE) has been used. It was found that this inhibitor acts through adsorption on the metal surface. Also, adsorption obeys the Langmuir isotherm with a standard free energy of adsorption ( ΔG°ads ) of -40.81 kJ mol-1. Kinetic parameters (activation energy, pre-exponential factor, enthalpy of activation and entropy of activation) were calculated and discussed. E (%) values obtained from various methods used are in good agreement.

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