Investigation of Inhibition Performance of Phenytoin for Mild Steel Protection in HCl Solution: Electrochemical and Quantum Theoretical Approaches

In this study, the application potential of the expired "Epdantoin" drug which includes phenytoin (EP) as the corrosion inhibitor was investigated. For this purpose, the electrochemical impedance spectroscopy measurements and polarization curves were obtained for 168 hours immersion period in 0.5 M HCl in the absence and presence of various concentration of EP. The experimental results were compared with quantum theoretical parameters in order to present adsorption behavior of EP. The adsorption equilibrium constant and Gibbs free energy were calculated as 5000 M-1 and -31,05 kj mol-1, respectively. The calculated HOMO and LUMO values were -6.67 eV and -0.72 eV, respectively. Results indicated that EP is a convenient candidate of corrosion inhibitor for mild steel in HCl medium.