Analysis of the protection performance of admixed citronella and myrrh essential oil extracts on high carbon steel corrosion in CH3COOH and C6H8O7 solution

Protection performance of admixed citronella and myrrh essential oil extract (CNM) on the corrosion resistance of high carbon steel (HCS) in 3 M of CH3COOH and C6H8O7 solution was evaluated by potentiodynamic polarization, open circuit potential measurement, weight loss measurement, x-ray diffractometry and ATF-FTIR spectroscopy. Results showed CNM performed effectively in CH3COOH with optimal inhibition of 87.47% and 80.12% at 1.67% concentration from potentiodynamic polarization and weight loss. CNM performed poorly in C6H8O7 solution with highest value of 41.29% and 43.81% at 1.67% CNM concentration from both tests. In both acids inhibition efficiency increased with increase in CNM concentration coupled with the exhibition of mixed-type inhibition effect. Open circuit potential plots show CNM significantly reduces the activation barrier for HCS to corrode wherewith the plots in the presence of CNM extract where significantly electropositive compared to the plot from C6H8O7 solution without CNM. In CH3COOH, the action of protonated CNM molecules and CH3CO2− anions results in the formation of complexes that increases the reactivity of HCS surface and its thermodynamic tendency to corrode despite effective inhibition performance. X-ray diffractometry shows admixed extract caused significant decrease in intensity/counts for diffraction peaks of Fe2O3 and Fe3O4 compounds on the spectrum plots compared to the plots without the extracts. ATF-FTIR spectroscopy shows significant reduction in transmittance at specific range of wavenumbers occurred within CNM/CH3COOH solution after corrosion, and on HCS surface after corrosion in the presence of the extracts compared to CNM/CH3COOH before corrosion. This contrast the results obtained from CNM/C6H8O7 solution.