EVALUATION OF ANTI-CORROSIVE EFFICIENCY OF OMEPRAZOLE BY ELECTROCHEMICAL METHODS

The release into the environment during disposal of unused and expired drugs, medical institution residues and waste, and pharmaceutical industry waste leads to its pollution and threat to public health. One of the methods for solving the problem of improper disposal of medicines is the possibility of using them as metal corrosion inhibitors. In this work, the anticorrosive protection of carbon steel in solutions of hydrochloric and sulfuric acids with the expired drug omeprazole was investigated using electrochemical methods. The studies were carried out using the methods of potentiodynamic polarization, electrochemical impedance spectroscopy and electrochemical diffusion technique. The concentration of omeprazole varied within 10–60 mg/L. According to polarization measurements, the protective effect of omeprazole at 40 mg/L reaches 84% in 1 M HCl solution and 92% in 0.5 M H₂SO₄ solution due to inhibition of both partial electrode reactions. According to impedance measurements, the protective effect values are 76% and 84%, respectively. The adsorption of omeprazole on steel, the surface coverage, and the subordination of adsorption to the Langmuir isotherm were estimated. The value of free energy of adsorption –ΔG^o_ads was calculated. Using the electrochemical diffusion method, the diffusion of hydrogen released during corrosion into the metal and the inhibitory effect of omeprazole on this process were estimated.

expired drug, omeprazole, inhibition, corrosion, steel, potentiodynamic polarization, impedance spectroscopy, diffusion method