Synergistic effect of Zn2+ and ATMP in corrosion inhibition of mild steel in neutral environment

Synergistic effect of Zn2+ and sodium salt of aminotrimethylene phosphonic acid (ATMP) in corrosion inhibition of mild steel in water containing low concentration (60 ppm) of Cl- has been evaluated by weight loss method. The results show that 98% inhibition efficiency is achieved with the binary system consisting of 200 ppm ATMP and 50 ppm Zn2+. Potentiostatic polarization studies show that while ATMP alone acts as anodic inhibitor, ATMP-Zn2+ combination acts as mixed inhibitor. The mechanistic aspects of corrosion inhibition and the nature of the film formed on the metal surface have been analysed with the help of UV-Visible reflectance spectra, FTIR spectra, luminescence spectra and XRD patterns. The protective film appears to be consisting of Fe2+ - ATMP complex and Zn(OH)2 which is also found to be luminescen