Insights into corrosion inhibition of aluminum in hydrochloric acid solutions using expired cephalosporins and klavox: Chemical, electrochemical and theoretical approaches

The inhibitory efficacy of two expired antibiotic drugs namely, cephalosporin and klavox against corrosion of aluminum in 1.0 M HCl solution was investigate utilizing potentiodynamic polarization (PDP) impedance spectroscopy (EIS) and weight reduction (WR) methodologies. It was discovered that the two expired drugs act as excellent inhibitors and the inhibition efficacy increases as the drug concentration increases and the temperature decreases. The inhibition efficacy reached 97.62 % and 99.42 % at 900 ppm of cephalosporin and klavox at 298 K, respectively. Expired drugs act as a mixed type inhibitor, controlling primarily the anodic and cathodic process, as evidenced by the PDP curves. According to EIS analysis, the charge transfer resistance values increased with increasing inhibitor concentration. The adsorption isotherm demonstrates that the expired drugs become active by physical adsorption on the Al surface, and their adsorption obeys the Langmuir isotherm. Through quantum chemistry calculations, the relationship between the inhibition properties and molecular structure was studied.