Corrosion Inhibition of A9 Steel In 1M Hydrochloric Acid by the Antioxidant Compounds of Methanolique Extracts for two Varieties of Olive Leaves: Chemlal and Rougette

This work is devoted to the corrosion inhibition of A9 steel in 1M hydrochloric acid HCl by the antioxidant compounds «polyphenol» of methanolique extracts for two varieties of olive leaves: Chemlal and Rougette (cultivated varieties). Two extraction methods are used for both varieties, the conventional method is maceration and the other one is ultrasound assisted method to give the best yield. The inhibitory effect was evolved by: gravimetric and electrochemical the methods. The thermodynamic parameters and the adsorption isotherm were evaluated to explain the mechanism of inhibition and the metal-inhibitor interactions. It has been found that the adsorption of the molecules of these products on the surface is made according to the Langmuir isotherm. The obtained values of the free energy of the adsorption show that these extracts are physisorbed on the steel.