Comprehensive study of the behavior of copper inhibition in 1 M HNO3 by Euphorbia Helioscopia linn. extract as green inhibitor

The inhibitive effect of the Euphorbia Helioscopia linn. extract (EHE) on the corrosion of copper in 1 M HNO3 has been evaluated by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The calculated adsorption thermodynamic parameters indicated that the adsorption was a spontaneous, exothermic process accompanied by an increase in entropy. The inhibition efficiency increases with increasing the concentration of the inhibitor in the medium and decrease with increasing the temperature. The maximum inhibition approached to 91% in the presence of 500 ppm EHE using Tafel polarization technique. The results show that EHE is an effective corrosion inhibitor for protecting the corrosion of copper in 1 M HNO3 medium even at stimulated conditions.