Some Schiff base compounds as inhibitors for corrosion of carbon steel in acidic media

The corrosion behavior of carbon steel in 0.5 M HCl solution in the absence and presence of new five Schiff bases of indole derivatives was investigated using electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) and potentiodynamic polarization techniques. All the experimental results show that these Schiff bases have excellent corrosion inhibition performance. The polarization curves show that these compounds act as mixed type inhibitors. The adsorption of these Schiff bases on carbon steel surface is consistent with Langmuir adsorption isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds were also studied. Some thermodynamic functions were computed and discussed. The results obtained by the three different electrochemical techniques were in good agreement.