Abstract
INHIBITION OF CORROSION OF CARBON STEEL IN SEAWATER BY 2-CARBOXYETHYL PHOSPHONIC ACID AND NI2+ SYSTEM

The inhibition of the corrosion of carbon steel in seawater by 2-carboxyethyl phosphonic acid (2-CEPA) and Ni2+ has been investigated using weight loss and electrochemical measurements. The results show that 73% inhibition efficiency is achieved with binary system consisting of 250 ppm of 2-CEPA and 50 ppm of Ni2+. Polarization study reveals that 2- CEPA – Ni2+ formulation functions as a cathodic inhibitor, which controls the cathodic reaction predominantly and to some extent controls the anodic reaction. AC impedance spectra reveal that a protective film is formed on the metal surface. Surface evaluation techniques like FTIR and SEM were used to determine the nature of the protective film formed on the metal surface.