Corrosion Inhibition of Aluminium by Alchemilla vulgaris L. Extract in 3 % NaCl Solution

Extract of Alchemilla vulgaris L. was investigated as eco-friendly corrosion inhibitor for aluminium in 3 % NaCl using electrochemical techniques. According to the results, inhibition efficiency increases with the increase concentration of extract and the highest efficiency (similar to 80 %) is recorded for the maximal concentration of extract (1.0 g L-1). The inhibition activity of extract occurs by the spontaneous physisorption (Delta G approximate to -16 kJ mol(-1)) on active sites of aluminium surface that follows Freundlich isotherm. Polarization curves showed that Alchemilla vulgaris L. extract acts a mixed-type inhibitor. The effect of temperature on the aluminium corrosion and inhibition action of extract was studied and the result showed that the corrosion rate increased and the inhibitor efficiency decreased with increase of temperature. The calculated values of the activation energy confirmed presence of inhibitive Alchemilla vulgaris L. extract on aluminium surface.