Ethanol extract of Ocimum gratissimum as a green corrosion inhibitor for the corrosion of mild steel in H2SO4

摘要

The potential of ethanol extract of Ocimum gratissimum as a green inhibitor for the corrosion of mild steel in H_2SO_4 was investigated using gasometric, gravimetric, and thermometric methods of monitoring corrosion. The results obtained, indicated that ethanol extract of O. gratissimum is an adsorption inhibitor for the corrosion of mild steel. The inhibition efficiency of the inhibitor was found to decrease with increase in the period of contact and with increasingtemperature, but increased with increase in the concentration of the inhibitor. From the observed trend for the variation of inhibition efficiency with temperature and the range of values obtained for activation energy (52.24-55.24 kJ mol-1) and free energy of adsorption (-19.15 to -17.06 kJ mol-1), a physical adsorption mechanism is proposed for the adsorption of the inhibitor on the surface of mild steel. In addition, the adsorption is exothermic, spontaneous, and is best described by Langmuir adsorption isotherm.