Dual-acting mechanism of microbial corrosion inhibition by ginger extract against nitrate-reducing bacteria in a nutrient-deficient environment.

This study investigates the efficacy of ginger extract (GE) as a green corrosion inhibitor in the petrochemical industry, specifically targeting microbial corrosion in carbon steel pipes utilized for river water coolant systems. The nutrient-deficient conditions coupled with the presence of nitrate-reducing bacteria (NRB) within these pipelines facilitate microbiologically influenced corrosion, wherein bacteria directly interact with the metal to harvest electrons for metabolic processes. Our findings indicate that GE inhibits microbial corrosion through dual mechanisms: significantly reducing biofilm formation and adsorbing onto the metal surface. Biofilm inhibition was assessed through both qualitative and quantitative assessments, employing light microscopy and confocal laser scanning microscopy (CLSM) to visualize and confirm the suppression of biofilm development by NRB in the presence of GE. Electrochemical techniques, including electrochemical impedance spectroscopy (EIS) and polarization measurements, demonstrated that GE achieved an inhibition efficiency nearing 95%. Further analysis via scanning electron microscopy (SEM) and adsorption studies corroborated the effective adsorption of GE on carbon steel, highlighting the importance of concentration and immersion time in performance outcomes. Notably, elevated concentrations of GE were found to enhance inhibitory effects, with a 7-day exposure period yielding optimal surface coverage. These results establish GE as a promising and environmentally friendly alternative for mitigating microbial corrosion in industrial applications. PRACTITIONER POINTS: The presence of nitrate-reducing bacteria (NRB) and a nutrient-starved environment are commonplace in the coolant pipes carrying water and can cause severe damage to carbon steel pipes. Ginger extract (GE), an inexpensive green corrosion inhibitor, can be a potent microbial corrosion inhibitor in petrochemical industries. The high efficiency (95%), achieved with ginger extract (GE), is due to its dual-acting mechanism: It inhibits the formation of bacterial biofilm on the surface of carbon steel by providing a non-conducive environment for bacterial growth. The components of GE get adsorbed over the surface of carbon steel and hence prevent bacterial attachment. An optimal concentration of 0.5 g/L GE was required to exhibit high efficiency (95%), which can be achieved on 7 days of exposure of carbon steel to GE, in the presence of NRB in a nutrient-starved environment.