Stem extract of Brahmi (Bacopa monnieri) as green corrosion inhibitor for aluminum in NaOH solution

Abstract

The stem extract of Bacopa monnieri was investigated as corrosion inhibitor of aluminium in 0.5 M NaOH solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) methods, and weight loss measurements. The results revealed that Bacopa monnieri stem extract was an effective inhibitor, and the inhibition efficiencies obtained from polarization and weight loss experiments were in good agreement. Using the potentiodynamic polarization technique, the extract proved to be a mixed-type inhibitor for aluminium in alkaline solution by suppressing both anodic and cathodic reactions on the metal surface. The Langmuir adsorption isotherm model fitted results obtained from the weight loss. Thermodynamic parameters such as activation energy, free energy of adsorption were calculated. © 2012 by ESG.