Inhibition Efficacy of Expired Citalopram Drug Towards the Damage of C-steel in Hydrochloric Acid Solution

The effectiveness of expired citalopram (Cp) as a corrosion inhibitor for C-steel in hydrochloric acid solution was investigated. Chemical and electrochemical measurements were utilized. The damage rate was reduced with an increasing concentration of the Cp compound. The protective performance is improved with increasing concentrations of Cp, achieving efficiency levels above 92.0% at 0.005 M and 25°C. The inhibition mechanism was attributed to the adsorption of Cp molecules onto the steel surface. The negative values of ΔG° indicate that the adsorption of Cp molecules occurs spontaneously. Depending on the solution temperature, the Δ G ^o _ads lie between − 36.16 and − 33.72 kJ/mol, emphasizing the physicochemical sorption process. The decline in K _ads values at elevated temperatures is ascribed to the desorption of Cp inhibitor species from the carbon steel surface into the solution. The high absorption energy values would suggest good protection properties of the Cp compound.