Synergistic and biocidal effects of 1-hydroxyethane -1, 1-diphosphate, Zn2+ and polycrylamide on the inhibition of corrosion of mild steel in neutral aqueous environment

Abstract

The formulation consisting of 300ppm 1-hydroxyethane-1, 1-diphosphonic acid (HEDP), 50ppm polyacrylamide (PAA) and 50ppm Zn2+ offered 99 per cent corrosion inhibition and 99 to 99.9 per cent biocidal inhibition to mild steel in neutral aqueous environment containing 60ppm Cl–, a situation commonly encountered in cooling water systems. The nature of the protective film formed on the metal surface was analysed using X-ray diffraction, Uv-visible reflectance, FTIR and luminescence spectra. The film was found to be luminescent and to consist of Fe2+-HEDP complex, Fe2+ -PAA complex and Zn(OH)2.