The corrosion inhibition character of thiosemicarbazide and its derivatives for C-steel in hydrochloric acid solution

The influence of thiosemicarbazide, phenylthiosemicarbazide Girad’s-T and phenylthiosemicarbazide Girard’s-P on the corrosion rate of steel in 2 M HCl has been studied. The protection efficiency obtained by weight-loss and potentiostatic polarisation techniques was found to be in good agreement with adsorption measurements at Pt electrode. The behaviour was correlated to the proposed skeletal representation of the adsorption mode of the inhibitors on the metal surface. Electrochemical results indicated that all the compounds investigated acted as cathodic-type inhibitors. The data obtained provide a good fit to both the Temkin adsorption isotherm and the kinetic–thermodynamic model recently proposed.