ZIZIPHUS SPINA – CHRISTI AS GREEN CORROSION INHIBITOR FOR AL-CU ALLOY IN ACIDIC AND ALKALINE MEDIA.

Ziziphus Spina – Christi extract (ZSC) was investigated as green corrosion inhibitor for Al-Cu alloy in acidic and alkaline media using chemical and electrochemical techniques. The weight loss results were interpreted by means of the kinetic –thermodynamic isotherm of extract adsorption on the alloy surface. The values of ranged from -5.08 to -23.43 kJ/mol revealed a strong physical and spontaneous adsorption of the ZSC on the alloy surface. The higher inhibition efficiency about 91.08% and 85.60% was observed at 8.0 g/L in 2.0M HCl and 1.5M NaOH. Activation parameters, ,and supporting the proposed physisorption mechanism. Potentiodynamic polarization measurements showed that the presence of ZSC extract in both media affects mainly the cathodic process, and decreases the corrosion rate to a great extent. The results obtained from weight loss and thermometric measurements are in a good agreement with potentiodynamic polarization measurements.