Metoprolol: New and Efficient Corrosion Inhibitor for Mild Steel in Hydrochloric and Sulfuric Acid Solutions.

The inhibition behavior of metoprolol tablet on steel alloy (st37) in 1 M hydrochloric acid and 0.5 M sulfuric acid solutions were studied by three methods (potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electronic microscopy, SEM). The obtained parameters revealed that different amounts of metoprolol drug inhibited the corrosion of mild steel in the acid solutions of HCl and H2SO4. The corrosion resistance of the alloy increased with the increase in the concentration of metoprolol up to 300 ppm but was reduced by increasing the temperature. The derived parameters from polarization curves indicated that the drug is a mixed type inhibitor. The results obtained from the different methods are consistent with each other. The adsorption of metoprolol was found to be physical, exothermic, and spontaneous, and also fitted the Langmuir adsorption model. SEM micrographs are in accordance with the adsorption performance of the tablet.