Abstract
Mild steel is material that cannot be overlooked in engineering for its vast usage, but corrosion is one of the
biggest concerns and threats to engineering. In the present study, the corrosion resistance of a nail made from
mild steel was used as the sample for this experiment. The solutions used were sodium hydroxide, sodium
chloride, and sulphuric acid. The inhibitor used was Orange Peel Extract (OPE) which was obtained from
roadside orange sellers in Ibadan, Nigeria. The inhibitor was added in different concentrations to each of the
three solutions to see its effect on the mild steel. Experimental procedures such as: weight loss, potentiodynamic
polarization (open circuit potential OCP and linear sweep voltammetry LSV), Scanning Electron Microscopy
(SEM), and EDS were used to investigate the effect of corrosion media on the behaviour of orange peel as a
corrosion inhibitor in mild steel. From the weight loss method used in knowing the corrosion rate, Sodium
chloride gave a corrosion rate of 5.92%, which was the lowest of the three solutions used. Sodium hydroxide is
the most corrosive of all three solutions used, reducing the weight of the sample very rapidly in a short time and
giving a corrosion rate of 10.9%, with sulphuric acid at 7.05%. Hence, for engineers looking at material
selection and considering the environment in which it could be used, this shows that mild steel cannot do well in
a sodium hydroxide environment. From the potentiondynamic polarization, the result from the experiment on
mild steel sample in NaCl solution in the absence of an inhibitor gave a corrosion rate of 3.65 E−3, in the
presence of 1g/ml of OPE inhibitor, it gave a corrosion rate of 5.84 E−4, 5.47 E−3 respectively. A mild steel
sample in NaOH solution in the absence of an inhibitor gave a corrosion rate of 1.31 E−1, in the presence of
1g/ml of OPE inhibitor, it gave a corrosion rate of 1.00 E−1 and in the presence of 2g/ml of OPE inhibitor, it
gave a corrosion rate of 3.71 E−3. Mild steel sample in H2 SO4 a solution in the absence of an inhibitor gave a
corrosion rate of 1.30 E−2, in the presence of 1g/ml of OPE inhibitor, it gave a corrosion rate of 1.26 E−1 and in
the presence of 2g/ml of OPE inhibitor, it gave a corrosion rate of 1.64 E−2. Results from a further experiment
carried out via SEM/EDS followed in the shoes of the Potentiodynamic polarization and weight loss method. It
showed that mild steel samples got adequate protection from OPE inhibitors in NaCL and H2 SO4 media. In
NaOH solution, the impact of the inhibitor was very little to none, as the severe damage to the surface of the
mild steel was visible in the images in the absence and presence of OPE inhibitor. The corrosion rate of the
sample in H2 SO4 the solution was high, but with the intervention of OPE inhibitor, the rate dropped
significantly per concentration. NaCl , Even though not so corrosive, took protection from OPE inhibitor.
Traces of damage to the surface of the corroded sample in NaCl solution in the presence of a higher
concentration of OPE was minimal.
Keywords: Analysis, Concentration, Corrosion, Inhibition, Mild Steel, Solution.