Adsorption, Thermodynamic and Kinetic Studies of Azadirachta indica (AI) Bark Extract as a Potential Corrosion Inhibitor for Zinc in 0.25 M HNO3 Solution
2022
MUHAMMAD, SAIFULLAHI LAWAL | Ibrahim, Muhammad Bashir
The inhibition action and adsorption behavior of Azadirachta indica bark extract was studied on zinc in 0.25 M HNO3 solution using weight loss, FT-IR and SEM analysis. The result of the findings show that inhibition efficiency of the extract increases with increase in inhibitor concentration and decrease with rise in temperature. Corrosion rate was found to increase with rise in temperature and decrease with increase in inhibitor concentration. FT-IR and SEM analysis shows that there is adsorption of inhibitor molecules on metal surface which lead to decrease in corrosion rate. Adsorption isotherm study shows that experimental data obey Freundlich isotherm and the mechanism of adsorption follow physisorption. Adsorption thermodynamic study indicates feasible and spontaneous process from the large negative value of free energy. The value of enthalpy are all positives indicating endothermic nature of adsorption. The result of activation energy was found to be higher in the presence of inhibitor than its absence indicating the decrease in energy barrier of zinc dissolution process.
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