Study of the Inhibitive and Adsorptive Properties of Mild Steel in H2SO4 - Boscia senegalensis Plant Environment

Abstract

The inhibitive and adsorption properties of ethanol extract of Boscia senegalensis for the corrosion of mild steel in H₂SO₄ were investigated using weight loss, linear polarization, and scanning electron microscopy techniques. From the result, it was found that the corrosion rate of mild steel to decrease with an increase in the concentration of the inhibitor as well as increase with an increase in temperature of the environment. The inhibition efficiency of the inhibitor increases with increasing concentration but decreases with increasing temperature. The inhibition potential of ethanol extract of Boscia senegalensis is attributed to the presence of saponnin, tannin, phlobatanins, anthraquinone, cardiac glycosides, flavanoid, terpene, and alkaloid in the extract. The adsorption of the inhibitor on mild steel surface was found to be exothermic, spontaneous and is best described by Freundlich and Temkim adsorption model. The calculated values of activation energy, enthalpy of activation, entropy of activation, free energy of adsorption and the trend in the variation of inhibition efficiency with temperature, the mechanism of adsorption of the inhibitor by physical adsorption. Ethanol extract of Boscia senegalensis is a good adsorption inhibitor for the corrosion of mild steel in H₂SO₄. Tafel polarization analyses indicated that studied plant extract is a mixed type inhibitor.

Keywords: boscia senegalensis; polarization; adsorption.