Anti-corrosive Efficiency of Expired Propranolol Drug as a Corrosion Inhibitor on Mild Steel in Acid Medium

Propranolol is a pharmaceutical organic drug used for the treatment of high blood pressure, heart problems and anxiety diseases. The disposal of the expired drug threatens the environment, but still, it contains active components. The potentiality of the active components of the expired propranolol drug (EPD) has utilized to protect the mild steel corrosion in 1.0 M hydrochloric acid medium. Weight loss method, potentiodynamic polarization, ac-electrochemical impedance spectroscopy, scanning electron microscopy with energy disperse X-ray spectroscopy and atomic force microscopy (AFM) were used to investigate the expired propranolol drug’s capacity to defend mild steel surfaces against corrosion in 1 M HCl medium. The outcomes of the studies demonstrate that expired propranolol drug efficiently inhibits the corrosion of mild steel in 1.0 M HCl medium at various temperatures and inhibitor concentrations. The maximum inhibition efficiency obtained by the weight loss method was 89.81% at 0.01 M EPD concentration at 303 K. EPD has been determined to follow the Temkin’s adsorption isotherm model. The SEM–EDX and AFM images were indicated that the formation of protective layer on the surface of mild steel against the acid attack. Potentiodynamic polarization studies showed that the inhibition mechanism is mixed mode and predominantly cathodic control. The observed values of ∆G⁰_ads, indicated that the inhibitive effect is exothermic and spontaneous. Furthermore, the determined thermodynamic parameters suggest that the adsorption process is spontaneous.