Nitrilotris(methylenephosphonic acid) – Zinc Ions – Uric Acid: A New Ternary Formulation as Corrosion Inhibitor for Carbon Steel

A new ternary formulation containing Nitrilotris(methylenephosphonic acid) (NTMP), Zn and uric acid (UA) is proposed as a new corrosion inhibitor for carbon steel in low chloride aqueous environment on the basis of the results obtained by gravimetric measurements. The concentration of Zn in the formulation, required for effective an inhibition, could be reduced in presence of uric acid. The formulation is found to be effective in the pH range 4 to 9. The protective film formed by the inhibitor is stable for longer immersion periods and also under hydrodynamic conditions. Optimum concentrations of all the three components are found to be essential for both formation and maintenance of the protective film on the surface. The results of the present study reveal the strong synergistic effect existing among the three components of the inhibitor and infer the possibility of practical application of the inhibitor in cooling water systems. Keywords-NTMP; gravimetric studies; synergism; corrosion inhibition; carbon steel; uric acid