Corrosion inhibition of zinc by calcium exchanged beidellite clay mineral: A new smart corrosion inhibitor

• Development of eco-friendly corrosion inhibitor based on Ca 2+ -exchanged beidellite. • Improvement of corrosion inhibition by progressive release of Ca 2+ from host mineral. • Role of beidellite in trapping aggressive corrosion species such as Cl − , Na + and H + . • Valorization of natural Moroccan clay mineral. • Ca 2+ -BDT modified the physicochemical properties of electrolyte near zinc surface. The corrosion inhibition performances of zinc immersed in 0.1 M NaCl solution with and without CaCl 2 , Na + and Ca 2+ exchanged beidellite (BDT) clay mineral picked up from Agadir bassin (Morocco) was studiedby potentiodynamic measurements and electrochemical impedance spectroscopy. The chemical and microanalysis of Na + -BDT and Ca 2+ -BDT by different techniques reveal basal distances of clays, of about 1.22 and 1.48 nm respectively, consistent with the saturation of beidellite interlayer spaces with Na + and Ca 2+ ions surrounded by one and two equivalent layers of water respectively. EIS results and surface analysis show that Ca 2+ -BDT acts as a smart inhibitor on zinc surface by modifying the physicochemical parameters of electrolyte near the surface. The exchange reaction in BDT involves the concentration decrease or the “suppression” of Na + , CO 3 2 - and Cl − ions near the zinc surface.