Green Eucalyptus leaf extract: A potent source of bio-active corrosion inhibitors for mild steel.

Eucalyptus leaves extract (ELE) inhibition impact toward mild steel (MS) corrosion in the HCl solution was examined by combined experimental and computational studies. The degree of inhibition was investigated by EIS and polarization test. The EIS analysis results showed that the increase of ELE concentration led to the significant increment of charge transfer resistance. An inhibition efficiency of ~88% was obtained using 800 ppm ELE after 5 h exposure. Polarization test results indicated the mixed inhibition effects of ELE with slight cathodic prevalence. The i values for the uninhibited and inhibited (800 ppm ELE) samples were 0.93 μA/cm and 0.25 μA/cm, respectively. The ELE molecules adsorption on the surface of MS followed a Langmuir isotherm. Furthermore, the molecular simulation results evidenced the adsorption of ELE compounds on the iron surface.