ABSTRACT

The effectiveness of Garcinia kola and Irvingia gabonensis leaves extract in inhibiting aluminum corrosion in 1M HCL and 1M NaOH media were investigated. The phytochemical analyses of Garcinia kola and Irvingia gabonensis extracts revealed that they contain phytochemicals such as Saponin, Alkaloid, Flavonoid and Tannin. The gravimetric method, thermodynamic isotherms, potentiodynamic polarization (PDP) and Electrochemical impedance spectroscopy (EIS) were adopted in this research work. According to this study, the corrosion rate increases with increasing temperature and reduces when the plant extracts were introduced in both acidic and alkaline media. It was also observed that the effectiveness of both Garcinia kola and Irvingia gabonensis’s inhibition efficiency decreases with rising temperature and increases with respect to concentration and exposure time. For Irvingia gabonensis in 1M HCL, the highest inhibition efficiency was observed to be 98.99% for Irvingia gabonensis in 1M NaOH, It was observed to be 72.92% at g/L concentration. For Garcinia kola in 1M HCL, the inhibition efficiency was observed to be 99.38% at 1.0 g/L concentration for Garcinia kola in 1M NaOH, that there was no observable inhibition efficiency possibly because the molecules of the Garcinia kola is not in tandem with the molecules of 1MNaOH which may have caused desorption at the surface of the aluminum alloy. The results obtained in the PDP and EIS correlates with the gravimetric results, which is an indication that both Irvingia gabonensis and Garcinia kola are organic inhibitor of corrosion