Ethylenediaminetetraacetic Acid-Zn2+ System as Corrosion Inhibitor for Carbon Steel in Sea Water

Abstract

The inhibition efficiency of ethylenediaminetetraacetic acid (EDTA) in controlling corrosion of carbon steel in sea water in absence and presence of Zn²⁺ has been evaluated by weight loss method. The formulation consisting of 250 ppm EDTA and 50 ppm Zn²⁺ has 96 % inhibition efficiency. It is found that the inhibition efficiency of EDTA increases by the addition of Zn²⁺ ion. A synergistic effect exists between EDTA and Zn²⁺. Polarization study reveals that EDTA-Zn²⁺ system functions as mixed inhibitor and the formulation controls the cathodic reaction predominantly. FTIR spectra reveal that the protective film consists of Fe²⁺-EDTA complex and Zn(OH)₂. The surface morphology of the protective film on the metal surface was characterized by SEM study.