CORROSION RESISTANCE OF COPPER IN UNPOLLUTED AND SULFIDE POLLUTED SALT WATER BY METRONIDAZOLE

The corrosion inhibition of copper by metronidazole (MDA) has been investigated in unpolluted and sulfide polluted 3.5% NaCl. Electrochemical techniques showed that MDA is cathodic type inhibitor for copper, this behavior is clearly noticed from the open circuit potential, however the MDA renders the potential of copper to more negative. Potentiodynamic polarization curves showed that the efficiency in unpolluted and polluted sulfide salt water are 68% and 73% respectively. The polarization resistance Rp values obtained from EIS curves showed higher values in sulfide polluted than that obtained from the unpolluted salt water. These results indicated that, in the presence of sulfide ions, the protective MDA-copper complex showed higher stability. The Scanning Electron Microscopy SEM with Energy Dispersive X ray EDS spectra indicated that MDA prevented copper from sulfide attack by adsorption on the copper surface to form a protective film from MDA-copper complex.