Expired Etoricoxib as a corrosion inhibitor for steel in acidic solution

Abstract

Expired Etoricoxib was investigated as a green corrosion inhibitor for carbon steel in 0.5 M H3PO4 solution using electrochemical methods at 30 and 60 °C. Etoricoxib was shown to be an efficient inhibitor of carbon steel corrosion with an efficiency of 80.627% at an inhibitor concentration of 225 ppm at 30 °C and 63.803% at 125 ppm and 60 °C. The adsorption of Etoricoxib on the carbon steel surface followed a Langmuir adsorption isotherm. The polarization plots revealed that Etoricoxib acts as an anodic type inhibitor and the parameters of the inhibition process were calculated and discussed. The surface morphology of the carbon steel was analyzed using scanning electron microscopy and energy-dispersive X-ray analysis. The antibacterial activity of the inhibitor was also tested. Fourier-transform infrared spectroscopy confirmed the inhibitive role of Etoricoxib and the quantum chemical parameters showed good correlation with the inhibition efficiency. The highest and lowest occupied molecular orbitals, separation energy (ΔE), and the dipole moment (μ) were calculated and explained well by the experimental data.