Inhibition of corrosion of carbon steel in well water by arginine-Zn2+ system

Abstract

The environmental friendly inhibitor system arginine-Zn²⁺, has been investigated by weight-loss method. A synergistic effect exists between arginine and Zn²⁺ system. The formulation consisting of 250 ppm of arginine and 5 ppm of Zn²⁺ offers good inhibition efficiency of 98 %. Polarization study reveals that this formulation functions as an anodic inhibitor. AC impedance spectra reveal that a protective film is formed on the metal sur­face. The FTIR spectral study leads to the conclusion that the Fe²⁺- DL-arginine complex, formed on anodic sites of the metal surface, controls the anodic reaction. Zn(OH)₂ formed on the cathodic sites of the metal surface controls the cathodic reaction. The surface morphology and the roughness of the metal surface were analyzed with Atomic Force Microscope. A suitable mechanism of corrosion inhibition is proposed based on the results obtained from weight loss study and surface analysis technique.