Ziziphus mauritiana leaves extracts as corrosion inhibitor for mild steel in H2SO4 and HCl solutions

Abstract

The inhibition performance of extracts of Ziziphus mauritiana on mild steel corrosion in 0.5 M H₂SO₄ and 0.5 M HCl was investigated using gravimetric, electrochemical polarization, electrochemical impedance spectroscopy and scanning electron microscopic studies. The gravimetric results indicate that Ziziphus mauritiana leaves extract exhibits good inhibition efficiency in both the acids. Furthermore, the inhibition efficiency decreases with increase in temperature. Polarization measurements showed that the studied inhibitor is mixed type in both acids with significant reduction of cathodic and anodic current densities. Electrochemical impedance spectroscopy measurements revealed that the charge transfer resistance increases with increase in the concentration of Ziziphus mauritiana extracts. Various thermodynamic parameters such as activation energy, activation enthalpy and activation entropy are evaluated and discussed. Adsorption thermodynamic parameters are also computed, and SEM was used to analyze the surface adsorbed film.