Application of Expired Amoxicillin as a Green Corrosion Inhibitor for Carbon Steel in Acidic Conditions

Abstract

The aim of this study is to investigate the potential of expired amoxicillin as an environmentally friendly corrosion inhibitor for carbon steel (CS) in a 1.0 M hydrochloric acid (HCl) solution. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were employed to evaluate the inhibition efficiency, along with weight loss measurements over a concentration range of 50-300 ppm and a temperatures range of 303-333 K. SEM and AFM were used to analyze the surface morphology. Discoveries indicate that the expired amoxicillin is a mixed-type inhibitor, reaching the peak efficacy of 91.2 % at 300 ppm and 303 K. Adsorption is by the Langmuir Isotherm as an unstirred physical adsorption. The surface examination established the growth of a protective coating that minimized the corrosive losses. This research indicates the utility of the expired pharmaceuticals as a more affordable and cost-effective substitute corrosion inhibitor that is environmentally friendly.