Ocimum gratissimum extracts as green inhibitors for the management of microbiologically induced corrosion on buried metals

The application of green corrosion inhibitors is increasingly recognized as an eco-friendly approach to mitigating corrosion. This study investigates the inhibitory effects of ethanolic and aqueous extracts of Ocimum gratissimum (OG) on buried metals, focusing on managing microbiologically induced corrosion (MIC). Over a 28-day period, carbon steel coupons were conditioned with OG extracts and buried in spiked clayey loam soil containing produced water to simulate anaerobic MIC conditions. Experimental setups included OGEE (Ethanolic extract of OG), OGAE (Aqueous extract of OG), and a control without extracts. After 14 and 28 days, corrosion effects were assessed gravimetrically, calculating metal weight loss, corrosion rate, and inhibition efficiency. Results showed mean percentage weight losses of 0.87%, 0.82%, and 1.73% for OGEE, OGAE, and Control setups, respectively. The corrosion rates were 11.76 mpy for OGEE, 11.15 mpy for OGAE, and 23.43 mpy for the control. Inhibition efficiencies were 49.7% and 52.3% for OGEE and OGAE, respectively. One-way ANOVA and Tukey HSD post hoc tests confirmed significant reductions in mean percentage weight loss for both OG-treated setups compared to the control at 14 and 28 days, with no significant difference between OGEE and OGAE. The findings indicate that O. gratissimum extracts significantly reduce MIC in buried metals, providing an effective, sustainable approach to corrosion management in buried pipelines.