Phenylamine as Inhibitor for the Corrosion of Aluminum in Acidic Medium

The inhibition ability of phenylamine on corrosion of aluminium in phosphoric acid solution was investigated through weight loss method and characterized by using scanning electron microscopic and Fourier transform infrared spectroscopic analysis. The obtained results show that phenylamine served as a very good inhibitor in protecting the metal against the corrosive action of phosphoric acid. Generally, the inhibition efficiency increased with increase of inhibitor concentration and decreased with increase in temperature. Corrosion rate increases in both inhibited and uninhibited solution but significantly decreased further in the presence of inhibitor. The positive values of enthalpy prove the endothermic nature of the dissolution process and the negative values of Gibbs free energy of adsorption prove the spontaneity of the entire process. The adsorption of the inhibitor on the surface of aluminium in phosphoric acid was found to obey Langmuir’s adsorption isotherm. The result of scanning electron microscopy (SEM), confirmed the existence of an absorbed protective film on the metal surface.