Comparative analysis of corrosion inhibition effects of mebendazole (MBZ) on mild steel in three different sulphuric acid concentrations

This study compares the electrochemical corrosion inhibition properties of various concentrations of MBZ (0-2.5 g/L) for mild steel in 0.5, 1.0 and 1.5 M sulphuric acid using potentiodynamic polarization (PDP) technique.Mebendazole was found to effectively impede the surface degradation of mild steel in the various concentrations of H2SO4 studied with maximum inhibition efficiencies of 97, 98 and 99% respectively.Inhibition efficiencies increased to these maximum values at 1.0, 1.5 and 1.0 g/L inhibitor concentrations respectively, before decreasing with subsequent increase in the concentrations of MBZ.Potentiodynamic polarization results suggest the mixed type inhibitor nature of MBZ in sulphuric acid.Corrosion current was observed to increase with acid concentration and significantly decreases with the addition of the inhibitor.Polarization resistance decreased as acid concentrations increased and was higher for higher inhibitor concentrations.From the results, corrosion current and corrosion rate were very high for the corrosion media without MBZ addition, while the polarization resistance was very minimal for the corrosion media without MBZ addition.There is a significant change to relatively smooth morphology, in the SEM micrographs of the mild steel immersed in the test solution with the MBZ, as a result of the interaction of MBZ with the active sites on the surface of the metal, which resulted in an enhanced surface coverage of MBZ molecules on the mild steel.