Synergistic effect of different Zn salts with sodium octanoate on the corrosion inhibition of carbon steel in cooling water
K. E. Mohamed, Omyma H. Ibrahim, Mohammed E. El-Bedawy, A. H. Ali
Abstract
The corrosion inhibition of carbon steel was investigated in cooling water containing sodium octanoate (Oct), Zn-salts or blends of Oct-Zn salts. The weight loss and the potentiodynamic polarization methods were applied. ZnCl2, ZnSO4 and Zn (NO3)2 were studied. The results showed that Oct-Zn salt blends exhibited higher corrosion inhibition efficiency than either Oct or Zn Salts added separately to the cooling water suggesting a synergistic interaction between Oct and the Zn-salts. The polarization results revealed that these blends act as mixed-type inhibitors with three dominant anodic inhibition. The inhibition efficiency of Zn-salts in the absence and presence of Oct was found to decrease in the order Zn (NO3)2 > ZnSO4 > ZnCl2. Optical microscopy and infrared spectroscopy were used to study the protective action of the films formed on carbon steel in Oct-Zn salt blends. The role of Zn anions and the synergism behavior were discussed.