Locust bean (Parkia biglobosa) pod extract as corrosion inhibitor on aluminium in acidic media its adsorption isotherm models
This work investigated the use of locust bean pod extract as an inhibitor to mitigate corrosion of aluminium metal in an acidic environment. Gravimetric weight loss method was used to study the corrosion process with a view to evaluating the weight loss, and adsorption isotherms parameters in the presence of the plant extract inhibitor. Phytochemical analysis was carried out on the locust bean pod extract, this revealed the presence of tannin, flavonoids and saponins compounds which suggest that the locust bean pod extract is a good green corrosion inhibitor. It was observed that the corrosion inhibition occurred by an attribute of inhibitor molecules adsorption on the surface of the aluminium metal which is seen to best fit to Langmuir adsorption isotherm model with the R2 value of 0.9982 in comparison to the other coefficient of determination values obtained from the other isotherms model used. However, more than one active sites of inhibitor were adsorbed on the surface of aluminium metal. The Gibb’s free energy values obtained ranges between (-0.072 – -19.735 kJ/mol) which confirmed the spontaneity, feasibility, and physical adsorption mechanism. This also indicates a strong spontaneous adsorption of the locust bean pod extract on the aluminium metal surface.
Keywords: Adsorption, Hydrochloric acid, Inhibition, Weight loss.
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