Drotaverine as a Corrosion Inhibitor for Carbon Steel in Hydrochloric Acid Media

The protective efficiency of expired drug Drotaverine at a concentration of 20–80 mg/L against corrosion of carbon St 3 grade steel in a 1 M solution of hydrochloric acid has been studied. The studies were carried out using gravimetry, potentiodynamic polarization, impedance spectroscopy, as well as scanning electron and probe microscopy. The effect of Drotaverine on the diffusion of hydrogen released in the course of steel corrosion into the metal has been estimated using a technique of electrochemical diffusion. Under daily corrosion testing at a room temperature, the protective efficiency of the drug amounted to 82%, whereas at 80°C this value has exhibited to be of 96%. Drotaverine decelerates both partial electrode reactions and hydrogen diffusion deep into the metal. Drotaverine adsorption on steel obeys the Langmuir isotherm.