Evaluation of Metoral pill as an effective and novel inhibitor for corrosion of mild steel in acidic media

In this study, the inhibition effect of metoral tablet as corrosion inhibitor for mild steel in 0.5 M phosphoric acid solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy, and the scaning electron microscopy techniques. The results showed that the maximum inhibition efficiency of this drug was found to be 300 ppm, and decreased with the increase in temperature for all of the solutions. Potentiodynamic polarization curves indicated that the inhibitor acts as mixed-type inhibitor and the corrosion current density decreased with increasing the inhibitor concentration. The results obtained from analysis of EIS data was in good agreement with those achieved by the polarization measurements. The adsorption studies indicated that the adsorption of the inhibitor on the alloy surface obeys Langmuir adsorption isotherm.The adsorption process is spontaneous and exothermic process and the entropy of adsorption in this solutions decreases.