Electrochemical, morphological and theoretical studies of an oxadiazole derivative as an anti-corrosive agent for kerosene reservoirs in Iraqi refineries

An oxadiazole derivative 4-[3-(4-methylphenyl)-1,2,4-oxadiazol-5-yl]-phenol (MOP) has been investigated as a protector against corrosion of mild steel tanks in Iraqi kerosene reservoirs using the Tafel approach. The extrapolation study was carried out in four temperatures (303, 313, 323 and 333 K) and five concentrations (100, 200, 300, 400 and 500 ppm) of MOP derivative. The results of the polarization study showed that the MOP inhibitor is classified as a mixed type and the activity of corrosion inhibition was estimated depending on Tafel curve. The highest performance of the inhibition efficiency (IE% = 88.95) was observed in 500 ppm of the MOP inhibitor at 303 K, and the results showed that the increase of IE% was related to increase in the temperature and concentration of the inhibitor. The calculated thermodynamic parameters confirmed that the nature of adsorption is physisorption and the inhibitor obeys Langmuir isotherm. Different morphological methodologies have been used to confirm the protected layer formation on the steel surface. Also, Fourier transform infrared (FT-IR) spectrophotometer was used to detect the interference method between the inhibitor and surface. The computational study was applied to show the active locations of inhibitor and study their relationship with the surface by density functional theory (DFT). Also, the biological efficacy of this inhibitor has been shown to have a good inhibition zone against some types of corrosive bacteria.