Abstract This work is on optimization and impedance study of inhibition efficiency of moringa leaf extract as corrosion inhibitor of aluminum in alkaline solution. Gravimetric method, polarization study and impedance measurement was employed in the corrosion inhibition study. Response surface methodology (RSM) was applied in the optimization process. Central composite design tool of design expert software version 9 was used to evaluate the effects and interactions of four variables of acid concentration (AC), inhibitor concentration (IC), temperature (T) and time (t) on the inhibition efficiency of the extract. Analysis of variance (ANOVA) was used to study the data generated. Moringa leaf extract exhibited optimum inhibition efficiency of 96.65 % at optimum inhibitor concentration of 1.5 g/L-1. The electrochemical impedance spectra revealed that moringa leaf extract acted as a mixed-type inhibitor. The extract is highly efficient in surface treatment of aluminum in alkaline environment.
Keywords Optimization, Corrosion, Aluminum, KOH, Moringa leaf.