The inhibitive effect of aqueous extract of Cassia acutifolia leaves
toward the corrosion of aluminum in 1 MHCl solution has been
investigated by weight loss measurements, galvanostatic,
potentiodynamic anodic polarization techniques and electrochemical
impedance spectroscopy technique. It was found that Cassia acutifolia
extract act as a good inhibitor for aluminum corrosion in the acid
solution. The inhibition action of the extract it was discussed in view of
the adsorption of its components on aluminum surface. It was found
also that the adsorption is a spontaneous process and follows Langmuir
adsorption isotherm. The inhibition efficiency (%IE) increase as the
extract concentration increased. Moreover, the effect of temperature on
the (%IE) was studied. The (%IE) decrease with increased the
temperature. It was found that the presence of extract increases the
activation energy of the corrosion reaction. Moreover, the
thermodynamic parameters of adsorption process were calculated.
It was found also that the extract provides a good protection to
aluminum against pitting corrosion in chloride ion containing solutions.