Effect of Zn ions on corrosion inhibition of aminotris (methylenephosphonic) acid for carbon steel in acidic solution

Author(s): Najoua Labjar, Souad ElHajjaji, H.Saufi, M.MekkaouiAlaoui, MounimLebrini, Fouad Bentiss, Charafeddine Jama

The synergistic effect of zinc ions on the corrosion inhibition of carbon steel in 1MHCl solutions by aminotris-tris (methylene phosphonic) acid (ATMP)hasbeenstudiedusingelectrochemical impedance spectroscopy (EIS), Tafel polarisationmethod, gravimetric measurement and inductively coupled plasma (ICP).The results revealed significant synergistic effect betweenATMP and Zn+2 which depend on themolar ratio, temperature and immersion time. The presence of Zn2+/ATMPinduces a decrease in anodic and cathodic currents. They act as a mixed–type inhibitor. The addition of zinc ions in acidic solution containingATMPinduces theformationofstablecomplexes and stabilizes the adsorption ofATMPon the steel surface. The synergistic effectwas observed betweenZn2+ andATMPwith an optimummolar ratio ofZn+2/ATMP = 5/5.

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