Protective efficiency of expired drug against acid corrosion of carbon steel

Expired drugs are studied as corrosion inhibitors of metals for more than 10 years.In the present work, the corrosion inhibitory effect of expired drug Omeprazole has been studied against carbon steel corrosion in 1.0 N hydrochloric and sulfuric acid solutions.The concentration of Omeprazole varied within 10-60 mg/L.The methods of gravimetry, potentiodynamic polarization, impedance spectroscopy were used at room temperature.The surface morphology of carbon steel samples after corrosion in the absence and in the presence of Omeprazole has been characterized by scanning electron microscopy.Analysis of the polarization curves in the solutions studied indicates that Omeprazole slows down the anodic and cathodic processes on carbon steel in both media.A decrease in the double-layer capacitance upon the introduction of the inhibitor into the media indicates the adsorption of its components on the metal surface.Impedance spectroscopy data made it possible to determine the adsorption isotherm and calculate the free energy of Omeprazole adsorption.The protective effect of the inhibitor at a concentration of 40 mg/L reaches 90% in both media.