The inhibiting ability of the fruiting bodies of
Melia azedarach Linn
extract (FB-MAL) and its synergistic e
ff
ect
with nickel ions (Ni
2+
) on the corrosion of carbon (C)-steel in hydrochloric acid were investigated using
gravimetric measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy
(EIS). The FB-MAL inhibited C-steel corrosion in acidic media up to 76.5%. Combining the FB-MAL with
Ni
2+
enhanced the adsorption capability of FB-MAL, greatly and consequently increased its inhibitive
e
ff
ect. Potentiodynamic polarization studies revealed that FB-MAL and FB-MAL + 100 ppm Ni
2+
behave
as mixed-type inhibitors. The EIS spectra showed that the charge transfer controls the corrosion
process. The studied system obeys the Langmuir adsorption isotherm. The kinetic parameters were
computed and are discussed later in this paper. The formation of the protective
fi
lm was con
fi
rmed
using Fourier transform-infrared spectroscopy, UV-Visible spectroscopy and scanning electron
microscopy.