Adsorption and inhibitive properties of Phoenix dactylifera L. Extract as a green inhibitor for aluminum and aluminum-silicon alloy in HCl

The inhibition efficiency of alcoholic extract of Phoenix dactylifera plant on aluminum and aluminumsilicon in 0.5 M hydrochloric acid solution have been evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM). Values of inhibition efficiency obtained are dependent upon the plant extract concentration and temperature. Generally, inhibition was found to increase with increasing the inhibitor concentration, but decreased with increasing the temperature. The effect of temperature on the corrosion behavior of Al and Al-Si alloy in 0.5M HCl with and without addition of plant extract was studied in the temperature range 20–60°C. Thermodynamic functions of dissolution processes were calculated from experimental EFM data and the interpretation of the results are given. Physical adsorption mechanism has been proposed for the inhibition and Temkin adsorption isotherm was obeyed for Al and Al-Si alloy.