Study the effect of expired tenoxicam on the inhibition of carbon steel corrosion in a solution of hydrochloric acid

The effect of expired tenoxicam drug as an inhibitor on the corrosion inhibition of carbon steel in 0.5 M HCl was examined at different concentrations. Besides, the effect of potassium iodide additives on inhibition was investigated. All of these are applied by three methods; electrochemical studies (electrochemical frequency modulation, potentiodynamic and electrochemical impedance spectroscopy, superficial studies (XPS, FTIR, and UV-spectroscopy) and theoretical studies (quantum chemistry calculations and molecular dynamic calculations). The presence of tenoxicam as an inhibitor in the solution gives an increase in charge transfer resistance and a decrease in the capacity of the double layer. Potentiodynamic polarization studies have demonstrated that tenoxicam is a mixed inhibitor. In this study, we examined the influence of temperature on the inhibition of corrosion of carbon steel, and we also computed the thermodynamic parameters. The potentiodynamic method designated that the inhibitor was used showed the best protection productivity of up to 81.0% for C-steel at 4 × 10−4 M from tenoxicam in 0.5 M HCl solutions at 30 °C. On the other hand, the inhibition efficiency (I%) increased synergistically on the addition of potassium iodide to 90.3%. Tenoxicam adsorption was found on the C-steel surface for Temkin's isothermal obedience. The mechanism of the inhibition process was discussed in light of the chemical composition and theoretical study of the inhibitor probe. Expired Tenoxicam was first studied as a carbon steel corrosion inhibitor in a solution of hydrochloric acid. It provides a way to deal with expired medications, thus reducing environmental pollution. The study explored the inhibition mechanism affecting expired tenoxicam, and provided theoretical support for the results obtained from experimental studies. The expired tenoxicam drug can be used as a cheap and safe corrosion inhibitor for the studied system.