Corrosion Inhibitors Based on Antibiotic Derivatives for Protection of Carbon steel Corrosion in Hydrochloric Acid Solutions

Some antibiotic derivatives namely, neomycin sulphate and amoxicillin were investigated as corrosion inhibitors for carbon steel in 1 M HCl solutions. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, electrochemical frequency modulation (EFM) and weight loss methods were used to study the inhibition action of carbon steel in 1 M HCl solutions at 30ºC. Electrochemical results showed that these compounds are efficient inhibitors for carbon steel and the efficiency reached to 81 %. The inhibition efficiency increases with the inhibitor concentration. The adsorption of these compounds on carbon steel surface follows the Freundlich adsorption isotherm. Polarization curves indicate that investigated antibiotic derivatives are mixed-type inhibitors. The Kinetic parameters of corrosion processes were calculated and discussed. The chemical and electrochemical methods gave similar results. The surface morphology was tested using scanning electron microscope with energy dispersive X-ray spectroscopy (SEM–EDX).