Inhibitory properties of Baphia nitida extract in acid mild steel corrosion

摘要

The inhibiting action of Baphia nitida plant extract on the corrosion of mild steel in 1 M H_2SO_4 and 2 M HCl was studied using hydrogen evolution method. The results showed that the leaf extract is a good inhibitor for mild steel corrosion in both acid media and better performances were obtained in 2 M HCl solutions. Inhibition efficiency and hence surface coverage were found to increase with increasing inhibitor concentration and decreasing temperature. The addition of halides to the extract enhanced the inhibition efficiency due to synergistic effect and showed that cationic species are responsible for the inhibition action of the extract. The synergistic effect was in the order KCl < KBr < KI and suggested a possible role of the radii of the halide ions. The apparent activation energy, E_a, and the heats of adsorption, ΔH_(ads), were calculated and the results revealed that the adsorption was physisorption mechanism.