Eco-friendly inhibitor L-valine - Zn2+-SG system controlling the corrosion of carbon steel in rain water

An eco-friendly inhibitor L-valine (LV) in controlling corrosion of carbon steel in rain water in the absence and presence of Zn2+ has been evaluated by mass loss method. The formulation consisting of 50 ppm of L-valine and 50 ppm of Zn2+ offers good inhibition efficiency of 74%. When 50 ppm of sodium gluconate (SG) is added to the formulations consisting of 50 ppm of LV and 50 ppm of Zn2+, the inhibition efficiency increases from 74% to 98%. As the immersion period increases, the inhibition efficiency does not alter. Polarization study reveals that this formulation functions as a mixed inhibitor. AC impedance spectra reveal the presence of a protective film on the metal surface. The FTIR spectra study lead to the conclusion that the Fe2+ - LV complex and Fe2+ - SG complex formed on anodic sites of the metal surface controlled the anodic reaction and Zn(OH)2 formed on the cathodic sites of the metal surface controlling the cathodic reaction. The Ecofriendly inhibitor L-valine - Zn2+-SG system may find in cooling water system