Inhibitive and Synergistic Properties of Ethanolic Extract of Anogeissus Leiocarpus Leaves on the Corrosion of Aluminium in HCl Solution

Abstract

The corrosion inhibition of aluminium in HCl in the presence of ethanol extract of Anogeissus leiocarpus at room temperature was studied using the thermometric technique. The effect of addition of halides (KCl, KBr, KI) is also reported. The percentage inhibition efficiency (% I) increased with increase in concentration of ethanol extract of Anogeissus leiocarpus. The addition of the halides to the plant extract increased the inhibition efficiency to a maximum of 95.18% with KI at 0.6g/L concentration. The higher the corrodent (HCl) concentration the higher the corrosion rate, while lower inhibition efficiency was observed in the absence and presence of the inhibitor and halides. The decrease in inhibition efficiency (and increase in reaction number values) was found to be in the order I⁻ > Br⁻ > Cl⁻ which clearly indicates that the radii and the electro negativity of halides play a significant role in the adsorption process. It was also noted that only KCl was synergistic to the ethanol extract of Anogeissus leiocarpus, while other halides tested were antagonistic. All the data acquired reveal that the ethanolic extract of Anogeissus leiocarpus act as an inhibitor in the acid environment due to the phytochemicals: saponin, tannins, flavonoid, anthraquinones, cardiac glycosides, alkaloids and steroid that it contains there in.

Keywords: Anogeissus leiocarpus, Corrosion inhibition, Halides, Phytochemicals, Synergism