Expired omeprazole as an effective corrosion inhibitor for copper in nitric acid

Researchers have investigated the effectiveness of an expired pharmaceutical drug, omeprazole, as a corrosion inhibitor for copper in 0.5 M nitric acid using mass-loss measurements conducted at different temperatures. The results demonstrated that the tested drug significantly reduced the corrosion rate of the copper alloy in the acidic medium. An inhibition efficiency of 97.7 % was achieved when 900 ppm of expired omeprazole was applied to the copper surface. Thermodynamic analyses were performed to determine the activation and adsorption parameters. The findings indicate that temperature and inhibitor concentration are the key factors influencing the corrosion behavior. The calculated Gibbs free energy of adsorption suggests that the inhibitor molecules adhere to the copper surface predominantly through physical adsorption. Furthermore, the adsorption process was found to follow the Langmuir isotherm, confirming that the pharmaceutical molecules naturally and spontaneously adsorb onto the copper surface. The research novelty lies in the application of an expired drug as a highly effective corrosion inhibitor under aggressive nitric acid environments. This offered cost-effective, ecofriendly, and alternative to conventional corrosion inhibitors.