Increase corrosion resistance of mild steel in sulfuric acid and hydrochloric acid solutions by metoclopramide tablet

Abstract In this article, metoclopramide tablet was thoroughly evaluated as an effective inhibitor for mild steel in 0.5 M sulfuric acid and 1 M hydrochloric acid solutions by different techniques (potentiodynamic polarization and electrochemical impedance spectroscopy [EIS]) and scanning electronic microscopy (SEM). The results revealed that the compound has a proper inhibiting effect at concentrations of 600 ppm for sulfuric acid and 300 ppm for hydrochloric acid solutions. The effect of temperature on the corrosion rate of alloy in the absence and presence of this drug was also studied. The EIS measurements revealed that by the addition of the inhibitor up to a certain concentration, the charge transfer resistance increases and the double layer capacitance decreases. The probe showed that the adsorption of the inhibitor on the alloy surface in both solutions follows Langmuir adsorption isotherm. This process is spontaneous and exothermic. The information obtained from SEM confirmed the formation of the protective layer on the surface of the sample after immersion in solutions containing the compound.