Usage of Grewia bicolor Juss leaves extract as green corrosion inhibitor for Steel XC40 in sulfuric acid medium

The inhibitive effect of a methanol extract of Grewia bicolor Juss (Gbj) leaves on the corrosion of XC48 steel in 0.5 M H2SO4 solution has been evaluated by weight loss measurement as well as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and surface characterization techniques. The presence of this extract brings down remarkably the corrosion rate of XC48 steel in 0.5 M H2SO4 solution. The results from this corrosion test clearly showed that the extract behaves as a mixed type corrosion inhibitor with the highest inhibition at 1500 ppm. The effect of temperature on the corrosion behavior of XC48 steel was studied in the range of 298-333 K. The activation and free energy values of the inhibition reaction support the hypothesis of a/the physisorption mechanism well described by the Langmuir equilibrium mode. Scanning electron microscopic (SEM) observations showed that the Gbj extract forms a protective layer over the metallic surface that isolates the metal from aggressive acid solution and protects it against corrosive dissolution. Finally, results of FTIR analysis indicate that the important role played by the oxygen atoms and aromatic rings in the process of adsorption.