Experimental and theoretical evaluations of Naproxen drug as a green corrosion inhibitor for carbon steel in an acidic medium

• A.K. Shams, R.A. Hammza, E.A. Salman, K.A. Samawi and T.A. Salman

Chemistry Department, College of science, Al-Nahrain University, Jadriya, Baghdad, Iraq

Abstract: A mix of experimental and theoretical methods were used to test naproxen’s (NAP) ability to stop carbon steel from rusting in a 1 M HCl solution. The experimental phase involved gravimetric analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. Theoretical calculations were carried out using density functional theory (DFT) at the B3LYP/6-311++G(p,d) level. These calculations aimed to ascertain the optimized molecular geometry and chemical inhibition parameters of Naproxen (NAP). Additionally, these theoretical techniques made it simpler to identify sites in both gaseous and liquid environments where nucleophiles or electrophiles might attack reaction centers by analyzing the condensed Fukui functions. In order to replicate realistic conditions for corrosion inhibition in solution, Monte Carlo simulations (MC) were employed. Gravimetric analysis shows as inhibitor concentration rises, there is a corresponding drop in corrosion rate and a rise in inhibition efficiency. The peak efficiency, reaching 94.96%, was attained at a concentration of 8×10^–3 M. It’s plausible that longer immersion durations lead to a greater inhibition effect by NAP. The calculated free energy values also showed that the interactions at the metal surface accurately reflected the physical and chemical features of the interactions between the metal surface and NAP inhibitor molecules. Studies using SEM and EDX showed that a protective layer of NAP formed on the carbon surface, effectively shielding it from severe acid-induced damage. Theoretical studies proved their accuracy in determining molecular geometric parameters and adeptly explaining chemical inhibition parameters. MC simulations underscored a strong propensity for adsorption, encompassing both chemisorption and physisorption. Significantly, the computed results closely matched the experimental data, confirming the effectiveness of NAP as a corrosion inhibitor.

Keywords: carbon steel, corrosion inhibitor, DFT quantum chemical descriptors, Monte Carlo simulations

Int. J. Corros. Scale Inhib., 2023, 12, no. 4, 1939-1963
doi: 10.17675/2305-6894-2023-12-4-27

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