I Danaee - Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran
M NiknejadKhomami - Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran
A.A Attar - Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran
M Peykari - Abadan Faculty of Petroleum Engineering, Petroleum University of Technology, Abadan, Iran

The electrochemical behavior of steel alloy in ethylene glycol-water mixture with different concentrations was investigated by polarization curves, AC impedance measurements, current transient and atomic force microscopy. The results obtained showed that corrosion rate was decreased with increasing ethylene glycol concentration. The effect of molybdate as inhibitor was studied and high inhibition efficiency was obtained. It was found that surface passivation was occurred in presence of inhibitor. The inhibiting effect of the molybdate was explained on the basis of the competitive adsorption between the inorganic anions and the aggressive Cl- ions and the adsorption isotherm basically obeysthe Langmuir adsorption isotherm.Thermodynamicparameters for steel corrosion and inhibitor adsorption were determined and reveal that the adsorption process is spontaneous. Also phenomenon of physical adsorption is proposed.

Steel 4130- Ethylene glycol- Corrosion- adsorption-molybdate