Phytochemical constituents of Taraxacum officinale leaves as eco-friendly and nontoxic organic inhibitors for stainless steel corrosion in 0.2 M HCl acid medium
Ugi BU, Obeten ME, Magu TO
Taraxacum officinale leaves were extracted of its phytochemical compounds (crude saponins, flavonoids and alkaloids) and used in the investigation of corrosion inhibitor of stainless steel in the presence of HCl acid solutions using methods ranging from weight loss, thermometric, potentiodynamic polarization and electrochemical impedance spectroscopy. The weight loss results revealed that the plant extracts are good corrosion inhibitors to the exposed metal. Electrochemical polarization data revealed a mixed mode of inhibition and the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameter (charge transfer resistance and double layer capacitance) with the change in concentration of the inhibitors was due to the adsorption of active molecules leading to the formation of a protective layer on the surface of steel. A physical adsorption mechanism was revealed from the inhibitor /metal interface and the Langmuir adsorption isotherm was well obeyed (R2 = 0.999). The thermodynamic parameter (ΔGads) proved inhibitors to be stabled on the metal surface and a spontaneous reaction process was recorded also.