Author/Authors :
Ouakki, Moussa Laboratory of materials - electrochemistry and environment - Faculty of Science - Ibn Tofail University, Morocco , Galai, Mouhsine Laboratory of Materials Engineering and Environment: Modeling and Application - Faculty of Science - University Ibn Tofail, Morocco , Cherkaoui, Mohammed Laboratory of materials - electrochemistry and environment - Faculty of Science - Ibn Tofail University, Morocco , Rifi, El-Housseine 3Laboratory of organic synthesis and extraction processes - Faculty of Science - University Ibn Tofail, Morocco , Hatim, Zineb Laboratoire d’Electrochimie et Traitement de Surface - Faculté des sciences - Université chouaibdoukkali, Morocco
Abstract :
The corrosion inhibition of mild steel in phosphoric acid solution containing a mineral compound based phosphate (apatite) was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy. Potentiodynamic polarization measurements reveal that the inhibition efficiency increased with the concentration of the apatite which appears to be a cathodic type inhibitor in the medium acid(H3PO4 2.0 M). Electrochemical impedance spectroscopy confirms this result, indeed the transfer resistance increases with apatite concentration. We note that the double layer capacitance decreases simultaneously
suggesting the formation of an adsorbed layer on the mild steel surface. The inhibition mechanism has been elucidated by a thermodynamic study which showed that the film was formed by physi-sorption. The adsorption model obeys to the Langmuir adsorption isotherm. The parameters of activation energy was evaluated and discussed
Keywords :
Corrosion inhibitor , Electrochemical methods , Apatite , Mild steel , Acid medium
