In this work, the methanolic extract of Mentha Suaveolens (EMMS) has been studied as inhibitor mild steel in hydrochloric acid (1.0 M HCl) solution using by weight loss measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The presence of this extract reduces remarkably the corrosion rate of mild steel in acidic solution. The effect of temperature on the corrosion behavior of mild steel was studied in the range of 313-343 K. The inhibition mechanism estimated from temperature dependence of inhibition efficiency as well as activation parameters show that the extract inhibits corrosion via physical adsorption of the extract on the surface of the mild steel. Adsorption characteristic of the extract were approxilated by the Langmuir isotherm. The results from this corrosion test clearly reveal that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 2.0 g/L. Double layer capacitance, (Cdl) decrease indicates that a layer was form indicating the formation of a surface film. This reflects the inhibitor does retard the corrosion rate.
