Adsorption of organic corrosion inhibitors on iron in the active and passive state. A replacement reaction between inhibitor and water studied with the rotating quartz crystal microbalance

摘要: Abstract Adsorption of a carboxylic acid model compound and benzoic on iron from the liquid phase, in presence or not an amine base, was studied using rotating electrochemical quartz crystal microbalance (rEQCM). The investigated acid/base couples are models for corrosion inhibitors fully formulated protective coatings mild steel. resulted decrease mass electrodes because water is replaced volume occupied by adsorbing organic molecule. A simple taking into account molecular adsorbent molecules could explain measured loss. effect base characterizing individual adsorption behavior parts. From loss due to replacement upon adsorption, coverage calculated. resulting isotherms followed Langmuir–Freundlich which constant, standard free energy heterogeneity parameter be co-adsorption with found base. Indeed, showed highest constant metallic iron. Both adsorbed more easily than oxidized good correlation between EQCM data polarization curves found.