Corrosion Inhibition and Adsorption Properties of African marigold for the Corrosion of Mild Steel in Hydrochloric acid
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Date
2012
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Abstract
Inhibitive and adsorption properties of acid extract of flowers of African marigold (AMF) for the corrosion of mild
steel in hydrochloric acid medium was studied using weight loss and electrochemical studies. The results revealed that
acid extract of African marigold flowers inhibited the corrosion of mild steel. The inhibition efficiency of the extract
increases with increase in concentration of the extract, exposure time and temperature of the medium. The maximum
inhibition efficiency of 97% was obtained at 0.3%v/v concentration of the extract at room temperature.
Potentiodynamic polarization study clearly reveals that the extract controls both anodic as well as cathodic reactions.
Double layer capacitance (Cdl) and charge transfer resistance (Rct) values were derived from Nyquist plots. The
adsorption of extract components on the mild steel surface was found to follow the Langmuir adsorption isotherm.
The energy of activation, enthalpy of activation and entropy of activation for the dissolution process were determined
and discussed. A mechanism of adsorption of the flower components on the surface of the metal was proposed for the
inhibition behavior on the basis of FTIR study.