ABSTRACT

Vanillinthiosemicarbazone and its methyl,ethyl derivatives were tested for their corrosion inhibition towards mild steel in 1 N HCL solution at 298 K using weight loss, tafel polarization and electrochemical impedance spectroscopy techniques poterntiodynamic polarization and EIS techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors under the influence of various experimental conditions.these inhibitors revealed good corrosion inhibition efficiency even at low concentration like 1x10^-3  M towards mild steel in HCL medium comparison of corrosion inhibition efficiencies of the derivatives and their parent were also investigated polarization curves showed that the three studied compounds act as mixed type inhibitors.the effects of chemical structure of the three  tested inhibitors were discussed. Results obtained from OCP versus time, polarization and impedance measurements are in good agreement. Studies showed all the three compounds vanillinthiosemicarbazone (VTSC),vanillin -4-methylthiosemicarbazone (VMTSC) and vanillin -4- ethylthiosemi-carbazone (VETSC) on mild steel surface to act as mixed type inhibitors and to obey the Langmuir adsorption isotherm.

KEYWORDS: MILD STEEL, VANILLINTHIOSEMICARBAZONE (VTSC) VANILLIN -4-METHYLTHIOSEMICARBAZONE (VMTSC),VANILLIN-4-ETHYLTHIO SEMICARBAZONE (VETSC) POTENTIODYNAMIC POLARIZATION,ELECTROCHEMICAL  IMPEDANCE SPECTROSCOPY (EIS) AND SCANNING ELECTRON MICROSCOPY (SEM)