KINETICS OF STEEL CORROSION IN HYDROCHLORIC-ACID INHIBITED WITH TRANS-CINNAMALDEHYDE

Measurements of the kinetics of steel corrosion in hydrochloric acid inhibited with trans-cinnamaldehyde (TCA) indicate that both adsorption of TCA and formation of a continuously thickening polymer film are important features of the inhibition mechanism. Surfactants play a key role in facilitating the adsorption reaction. We propose that adsorption involves formation of a tenacious highly protective surface complex on the protonated chloride-covered steel. TCA can also undergo reduction at the surface, thus initiating polymerization reactions that lead to growth of a barrier film. However, film formation depletes the solution of TCA, which can affect the stability of the sorbed complex.