The inhibitory effect of the extract of leaves of Portulaca oleracea on the corrosion of aluminium was investigated by the weight loss method at the temperature range of 305 K to 315 K in 2 M H2SO4 solution. The inhibition efficiency (IE %)was found toincrease with increase in both the inhibitor concentration and temperature. The increase in IE% with rise in temperature is suggestive of chemical adsorption process. The unchanged value of activated energy, Ea, with change in concentration and increase in Gibb’s free energy value with rise in temperature are further evidence supporting the proposed chemical adsorption mechanism. The evaluated heat of adsorption values are all positive, an indication that the heat of adsorption process onto aluminum surface is endothermic.The negative values of entropy of activation, ΔS*ads,signify that the activated complex in the ratedetermining step represented an association, rather than dissociation.The data obtained best fitted the Langmuir, Freundlich, El-Awady and Temkin adsorption isotherms.
