Evaluation of the inhibitive effect of some plant extracts on the acid corrosion of mild steel

The toxicity of most synthetic corrosion inhibitors as well as recent environmental awareness provides sufficient motivation for the evaluation of natural products as potential alternatives. In response to this, the present paper presents the results of a series of studies in our laboratory on the inhibitive effect of selected plant extracts on the acid corrosion of mild steel using different electrochemical and non electrochemical techniques. The results indicate that all the extracts inhibited the corrosion process by virtue of adsorption of their phytochemical constituents on the corroding steel surface and inhibition efficiency improved with concentration of the active constituents. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms showed no generalized correlations, but our observed inhibition efficiencies, in excess of 95% in many instances, is adequate indication that some of these extracts are suitable candidate materials for the formulation of effective non toxic and environmentally friendly corrosion inhibiting additives.