Expired butamirate drug as eco-friendly corrosion inhibitor for aluminum in seawater: Experimental and theoretical studies

In this work, an expired butamirate drug (EBD) was used as a corrosion inhibitor for aluminum in artificial seawater (3.5% NaCl solution). The corrosion rate was evaluated as a function of temperature and inhibitor concentrations using the electrochemical polarization technique. These data indicated that the EBD acts as a mixed-type corrosion inhibitor with a slight effect on the cathodic reaction. Corrosion current densities increased with temperature and decreased with inhibitor concentration. At a temperature of 328 K and an inhibitor concentration of 24 ml/l, the maximum corrosion inhibition efficiency was 84.4%. The cyclic polarization test confirmed the greater pitting resistance in the presence of butamirate drugs in solution. Adsorption studies showed that EBD adsorbed chemically on the metal surface following the Langmuir adsorption isotherm. Electronic microscopy showed enhancements in the surface morphology in the presence of EBD. While FTIR was used for the diagnosis of functional groups in EBD and surface corrosion products. In addition, theoretical quantum chemical calculations were used as a powerful tool to support the experimental studies.