Évaluation des propriétés inhibitrices d’un sirop à base des extraits de plantes contre la corrosion

Abstract

This study aims to evaluate the inhibitory efficiency of a pharmaceutical product derived from medicinal plant extracts against copper corrosion in an acidic environment, using the gravimetric method. Several experimental parameters were investigated, including inhibitor concentration, solution temperature, and immersion time. The experimental results showed that the maximum inhibition efficiency, reaching 83%, was achieved at a concentration of 0.4% v/v, at 323 K, after one hour of exposure. The efficiency increased with both the inhibitor concentration and temperature, while prolonged immersion negatively affected its protective performance. The adsorption behavior of the inhibitor on the copper surface followed the Langmuir isotherm model, indicating monolayer adsorption. Theb calculated thermodynamic parameters revealed that the adsorption process is endothermic and occurs spontaneously. Moreover, the activation energy in the inhibited solutions was lower than in the uninhibited one, suggesting a modification in the corrosion mechanism. Negative values of activation entropy indicated that the transition state is more ordered than the initial reactants. These findings confirm that the studied syrup offers an effective and environmentally friendly alternative for mitigating copper corrosion in acidic media.