Abstract
Corrosion inhibition of aluminium alloy (AA3003) in 0.5 M HCl by extracts of selected plants was
investigated using gravimetric technique at 30 and 60°C. The studied plant materials include extracts
of Euphorbia hirta and Dialum guineense. The results indicate that all the extracts inhibited the
corrosion process in the medium by virtue of adsorption and inhibition efficiency improved with
concentration. Inhibition mechanisms were deduced from the temperature dependence of the
inhibition efficiency as well as from activation parameters that govern the process. Adsorption of both
plant extracts on the aluminium alloy was found to obey the Langmuir adsorption isotherm. The
phenomenon of physical adsorption is proposed from the obtained thermodynamic parameters.
Key words: Corrosion inhibition, aluminium alloy, acid solution, adsorption