Corrosion inhibition by HEDP-Zn2+ system for mild steel in low chloride media

The inhihition efficiency of HEDI' -Zn2 + system in cnntrolling corrosion of mild steel ill a nl'ut.-al u1lueous environment containing 60 ppm cr, a situation commonly encountered in couling water systems, has heen evaluated hy weight Inss study. Val-inus concenh-aliuns of HED!' (10, 50, 100 ppm) and variuus concentmtinns of Zn2 + (10, 50, 100, 150 ppm) have been used. A f41nllUlatiun is arrived at, which has 98% inhihition efficiency. The protective film has been analysed using X-my diffraction, F"fIR and uv-visihle reflectance spech·a. Tht' protective film conist~ of .'e*. HEDP complex and Zn(OH)2; free from any oxides of iron. The inl1uem'e of a biocide, namely, N-cl'tyl-N, N,N-trimethylammonium bromide (CrAR), on thl' corrosiun inhihition efficil'ncy of HEDP-Zn* system and also the influence of HErW-Zn* system on the biocidal effidt'ncy of CTAU have heen investigated