Experimental and computational study of Salvia officinalis leaf extract as an eco-friendly green corrosion inhibitor for zinc in 0.5 M sulfuric acid solution

• Musa E.M. Babiker

Department of Chemistry, Faculty of Science, Albaha University, Albaha 65779, Saudi Arabia

Abstract: Salvia officinalis is known to be rich in phytochemicals as flavonoids, saponins, tannins, glycosides, oils, and lipids. Leaf Extract of Salvia officinalis was studied as the corrosion inhibitor for zinc in 0.5 M H₂SO₄ utilizing a weight loss technique, and computational chemistry calculations. The study was done at different temperatures (25, 30, 35, 40 and 45°C) in the presence of the leaf extract of plant and the absence of extract. According to the density functional theory (DFT)/B3LYP/6-311G, a number of parameters were to be detected in this work, including the highest occupied molecular orbital EHOMO, the lowest unoccupied molecular orbital ELUMO, energy gap (ΔE), dipole moment (μ), hardness (η), softness (S), electronegativity (χ), and electrons transferred fraction (ΔN). The adsorption isotherms used to explain inhibitor adsorption behavior is the Langmuir adsorption isotherm. The adsorption mechanism includes a physical adsorption process. The results showed that with the increment of the inhibitors concentration, there was an improvement of the inhibition efficiency, and decreases with the rise in the temperature. The inhibition efficiency reached a value of 92.4% at 600 ppm of extract at 25°C. The contact area between zinc surface and of H₂SO₄ solution can be minimized by a film formed by the extract. Thermodynamic functions of adsorption and activation were determined and explained. The sign of free energy of adsorption confirm the spontaneous process. The computational results carried out on the extract compounds of Salvia officinalis leaf extract agree with the experimental one. The employed techniques explain the efficiencies in perfect correspondence, demonstrating the validity of these methods.

Keywords: zinc, Salvia officinalis extract, corrosion inhibition, H2SO4, DFT

Int. J. Corros. Scale Inhib., 2024, 13, no. 3, 1777-1796
doi: 10.17675/2305-6894-2024-13-3-25

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