PORTUGALIAE ELECTROCHIMICA ACTA Inhibition of Corrosion of Carbon Steel in Sea Water by Sodium Gluconate -Zn 2+ System

Abstract The inhibition efficiency of sodium gluconate (SG)-Zn 2+ system in controlling corrosion of carbon steel in sea water has been evaluated by weight-loss method. The formulation consisting of 250 ppm of SG and 75 ppm of Zn 2+ has 98% IE. Influence of duration of immersion on the IE of SG-Zn 2+ has been evaluated. The mechanistic aspects of corrosion inhibition have been investigated by polarization study and AC impedance spectra. The protective film has been analysed by FTIR and luminescence spectra. The surface morphology and the roughness of the metal surface have been analysed by atomic force microscopy. The protective film consists of Fe 2+ -SG complex and Zn(OH) 2 . It is found to be UV -fluorescent