Corrosion phenomena, control and prevention are unavoidable scientific issues that should be addressed due to increase of technological development. Aluminium (Al) is one of the most abundant elements found in the earth’s crust. The applications site of Almakes it to yield corrosion attack despite its corrosion resistance. The aim of alloying is to enhance the desired properties possessed by the Al. Plant extracts are rich source of naturally synthesised chemical compounds that can be extracted by simple procedure. The present study investigated the corrosion inhibition of Al alloy in 0.75 M KOH solution at room temperature using Xylopia aethiopicaseed extract. The gravimetric technique was employed in the study. It was revealed that the presence of the spice extract in the test solution retards the corrosion rate. The calculated inhibition efficiency from the inhibitor surface coverage was observed to increase linearly with the inhibitor concentration. The consideration of the Langmuir adsorption isotherm indicated that the mechanism of adsorption is Physisorption. Temkin isotherm models explained that there were lateral attractions of the inhibitor molecules on the Al alloy surface. Flory-Huggins isotherm model confirms that there is bulky displacement of water molecules on the metal surface due to the presence of the inhibitor molecules. This depicts that the spice constituents clustered on the Al alloy surface preventing contact with the corrosive environment.
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