Adsorption and Corrosion Inhibition of Cu in Nitric Acid by Expired Simvastatin Drug

Abstract

The inhibition effect of expired Simvastan drug on Cu corrosion in 1 M HNO₃ at 25°C was investigated using potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS) and electrical frequency modulation (EFM) as well as weight loss (WL) measurements. Electrochemical studies data support that examined expired drug is an efficient inhibitor for mild steel corrosion. The adsorption of the examined drug obeys Langmuir’s adsorption isotherm. Polarization studies indicate that this inhibitor acts as a mixed type inhibition. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were calculated and discussed. The protective film formed on the surface was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The results collected from the studied techniques are in good agreement to confirm the ability of using expired Simvastan drug as corrosion inhibitor for Cu in acid media. The relationships between the inhibition efficiency (%IE) and some quantum chemical parameters have been discussed.