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.