Adsorption and Corrosion Inhibition of Epiphyllum oxypetalum Leaf Extract on Aluminum Alloy AA5052

Aim: The corrosion inhibition mechanism of aluminium Alloy AA5052 has been studied in acidic solution. The study used gravimetric and electrochemical impedance spectroscopy to verify the inhibition efficacy of Epiphyllum Oxypetalum Leaf Extract At Varied Concentrations.

Study Design: Laboratory research was conducted at a maximum exposure time of nine (9) hours.

Place and Duration of Study: The research was carried out at Material Science group laboratory, Abia State Polytechnics, Aba Abia State, Nigeria between May 2018 and July 2018.

Methodology: Gravimetric technique was employed at varied temperatures to note the general inhibitive behaviour of the leaf. Electrochemical Impedance Spectroscopy (EIS) technique was employed to determine the electrochemistry process. The leaf extraction was done with reflux set up under 65°C.

Results: An Optimal Inhibition Efficiency Value of 97% was obtained. The inhibition efficiency increased with increasing concentration of the inhibitor but decreases slightly with the increase in temperature. The electrochemical studies showed that the green leaf extract was able to alter the electrochemical mechanism of the corrosion process. The corrosion current densities icorr and mass electron/charge transfer were observed to reduce due to the presence of the inhibitor in the test solution. The thermodynamic parameters were studied. Adsorption mechanism of the inhibitor molecules obeyed Langmuir and Temkin adsorption models. The calculated adsorption Gibb’s free energy is negative showing that the adsorption process was spontaneous. OPTICAL micrograph was used to study the surface morphology of the metal surface. Vickers indentation studied on the metal showed how the inhibition process improved the mechanical hardness of the corroded metal.

Conclusion: Epiphyllum oxypetalum extract has been developed as a corrosion inhibitor for aluminium alloy AA5052 in the hydrochloric acidic environment.