Ficus polita (Bush Fig) Leaves Extract as Corrosion Inhibitor of Aluminium in Alkaline Medium

Abstract

Corrosion inhibition of aluminium in alkaline solution by Ficus polita at 303, 313 and 323K was studied using weight loss technique and electrochemical measurements. Weight loss and electrochemical data were used for further calculation of some corrosion parameters. The percent inhibition efficiency (%IE) increased with concentration of F. Polita. Temperature increased the corrosion rate but decreased the inhibition efficiency between 303, 313 and 323K in the absence and presence of the inhibition respectively. Physical adsorption was proposed from Ea values obtained. The increase in the percent inhibition efficiency as well as the surface coverage (θ) indicated that the adsorption of F. Polita on the reaction sites of NaOH plays an important role in the adsorption process. Adsorption isotherms were fitted by Langmuir isotherm. The electrochemical results indicated that the investigated compound acts as mixed – type inhibitor. Some thermodynamic parameters were also determined to investigate the mechanism of corrosion inhibition (Goads) and kinetic parameters were evaluated. The presence of – C =O and –N=N-, etc groups in F. Polita was found to have contributed greatly to the inhibition process by interacting with aluminium surface.Keywords: Ficus polita, polarization, inhibition, FTIR, adsorption isotherm