Quantum chemical studies and Adsorption Characteristic of 4-hydroxy-3-[1- (2-phenylhydrazinylidene) ethyl] 2H-1-benzopyran-2-one on Mild Steel in Hydrochloric Acid

The corrosion of mild steel in hydrochloric acid containing 4-hydroxy-3-[1-(2- phenylhydrazinylidene) ethyl] 2h-1-benzopyran-2-one (hpbo) has been studied at different inhibitor concentrations and temperatures. the effects of the inhibitor have been demonstrated using weight loss and electrochemical measurements. the increase of the inhibitor concentration leads to a decrease in the corrosion rate and in the corrosion current. inhibition efficiency of 4-hydroxy-3-[1-(2-phenylhydrazinylidene) ethyl] 2h-1-benzopyran-2-one increases with the concentration of inhibitor and decreases with the increase of temperature. the potentiodynamic polarization carried out in 1 m hcl in the absence and presence of the inhibitor clearly proves the fact that this compound behaves as a mixed inhibitor. the adsorption of this compound on the mild steel surface obeys langmuir's adsorption isotherm. semi-empirical molecular orbital calculations of hpco, as molecular model gave useful information to predict the interaction between the surface of metal and the organic molecule as corrosion inhibitor.