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Article – Journal of Advanced Electrochemistry

Journal of Advanced Electrochemistry, Volume 3,Issue 2,2017 Pages 148-151

Electrochemical Analysis of Piliostigma thonningii (Monkey Bread) Leaf Extract as Corrosion Inhibitor of Aluminium in Alkaline Medium
A.I. Onen*, J. Buba, D.A. Apagu

Inhibition of aluminium corrosion in alkaline environment by Piliostigma thonningii at 303, 313 and 323 K was studied using gravimetric and electrochemical measurements. The weight loss and electrochemical data used for further calculation of some corrosion parameters. The percent inhibition efficiency (%IE) increased with concentration of P. thonningii. Temperature increased the corrosion rate but decreased the inhibition efficiency between 303, 313 and 323 K 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 P. thonningii 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 (GO ads) and kinetic parameters were evaluated. The presence of – C =O and –N=N-, etc., groups in P. thonningii was found to have contributed greatly to the inhibition process by interacting with aluminium surface.

Keywords: Piliostigma thonningii; Polarization; Inhibition Efficiency; FTIR; Physisorption;