Corrosion inhibition of mild steel in acidic medium using 2-amino thiophenoland 2-cyanomethyl benzothiazole

The corrosion inhibition characteristics of 2-amino thiophenol (ATP) and 2- cyanomethyl benzothiazole (CNMBT) on two types of steel in 1m HCl medium we re investigated at different temperatures (25, 30, 35, 40 and 50 degreesC). The pitting corrosion behaviour for the same system was studied using a po tentiodynamic technique. The pitting corrosion resistance of steel samples increased with increase in concentration of the ATP and CNMBT. Some samples were examined by scanning electron microscopy. The effects of the inhibito rs on the general corrosion of the two samples were investigated by using g ravimetric and galvanostatic polarization techniques. The inhibition effici encies increased with increase their concentration but decreased with incre ase in temperature. Free energies of activation, enthalpies and entropies f or the inhibition processes were determined from rate constant data measure d and different temperatures at different concentrations of ATP and CNMBT. Results were compared with fits obtained from the application of the Langmu ir isotherm. Results were correlated to the chemical structure of the inhib itors. The inhibition efficiency of CNMBT is higher than that of ATP.