Moringa oleifera plant extract as a copper corrosion inhibitor in binary acid mixture (HNO3 + H3PO4)

The behavior of Cu in 1 M mixture of nitric and phosphoric acids containing different concentrations of moringa oleifera leaves (MOL) extract has been studied by weight loss (WL) and electrochemical techniques [potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM)]. The maximum inhibition efficiency was found to be 89% at concentration 0.300 mol L-1 of the extract at 298K after 3 hours immersion period. The inhibition efficiency (IE) increased with increasing the extract concentration while decreased with increasing the temperature indicates that the extract is physically adsorbed on Cu surface. The adsorption of the extract follows Langmuir adsorption isotherm. Some thermodynamic parameters of activation and adsorption processes were also determined and discussed. Surface analysis was also studied.