Expired Metheprim drug as a corrosion inhibitor for aluminum in 1 M HCl solution: Experimental and theoretical studies

• H.A. Abdullah¹, R.A. Anaee¹ and A.A. Khadom²

¹ Department of Materials Engineering, University of Technology, Alsinaa Street, Baghdad 10001, Iraq
² Department of Chemical Engineering, College of Engineering, University of Diyala, Baquba City 32001, Diyala governorate, Iraq

Abstract: In the past decades, there are much interest to the replacement of harmful corrosion inhibitors with other effective ones by using drugs and other natural materials of plant origin for corrosion inhibition. In this work, the corrosion inhibition properties of expired Metheprim were investigated at five different concentrations (0.1, 0.2, 0.3, 0.4 and 0.5 M) in 1 M HCl at three temperatures (303, 313 and 323 K). The experimental data indicated that Metheprim is a cathodic inhibitor for Al that gave an inhibition efficiency of 99.5% at 0.5 M concentration and 303 K temperature. The polarization resistance increased from 1.5 to 54.8 Ω·cm² at 303 K at 0.4 M concentration. The results of inhibition were supported by FTIR and optical microscopy investigations. FTIR of pure Metheprim and the film formed on the metal surface indicated the adsorption of the inhibitor on the metal surface. Optical microscopy studies indicated that the presence of Metheprim reduces the corrosion damage. Quantum chemical calculations were used as a theoretical tool to confirm the experimental results indicating that the inhibitor acts as a donor of electrons to the metal surface.

Keywords: expired drug, Al, corrosion inhibition, acidic medium

Int. J. Corros. Scale Inhib., 2022, 11, no. 3, 1355-1373
doi: 10.17675/2305-6894-2022-11-3-26

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