The Inhibition of aluminium corrosion in hydrochloric acid solution by exudate gum from Raphia hookeri

The corrosion inhibition of aluminium in HCl solution in the presence of exudate gum from Raphia hookeri at temperature range of 30–608C was studied using weight loss and thermometric techniques. The exudate gum acts as an inhibitor in the acid environment. The inhibition efficiency increases with increase in inhibitor concentration but decreases with an increase in temperature. The inhibitive effect of the Raphia hookeri exudate could be attributed to the presence of some phytochemical constituents in the exudate which is adsorbed on the surface of the aluminium metal. The exudate gum was found to obey Temkin adsorption isotherm and Kinetic–Thermodynamic Model of ElAwady et al. at all the concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the activation parameters obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous.

1. Raphia hookeri exudates gum acts as an inhibitor for corrosion of aluminium in 0.1 M HCl solution. 2. The inhibition efficiency increases with increase in the concentration of RH but decreases with increase in temperature. 3. The inhibition is due to the presence of some phytochemical constituents in the exudate gum which is adsorbed on the surface of the aluminium metal. 4. The exudate gum (RH) was found to obey Temkin adsorption isotherm and kinetic– thermodynamic model of El-Awady et al. from the fit of experimental data. 5. The values of DGo are negative which sugads gest that the inhibitors were strongly adsorbed on the aluminium metal surface. The values obtained support the physical adsorption mechanism. 6. Thermodynamic parameters revealed that adsorption process is spontaneous.