An investigation into the use of West Indian Bayleaf ( Pimenta racemosa ) extract as a green corrosion inhibitor for biodiesel fuel and methanol blends in reciprocating engine applications

Biodiesel is considered a key alternative fuel as it has the potential to replace diesel in reciprocating engines. Despite the identification of effective commercial inhibitors, many of them have been found to have undesirable ancillary effects. Accordingly, this work sought to investigate the efficacy of the West Indian Bayleaf extract as an inhibitor for biodiesel and its methanol blends. It examined the impact of variations in extract concentration and temperature on the effectiveness of the extract for mild steel samples submerged in coconut oil biodiesel and biodiesel/methanol blends. Efficacy was assessed via gravimetric analyses, vibration frequency response tests and surface hardness tests. Further, electrochemical impedance spectroscopy was utilized to gain a more precise assessment of the extract’s inhibitor efficiency. A maximum inhibitor efficiency of 82% was recorded for a concentration of 2000 ppm in neat biodiesel. Moreover, in neat biodiesel, at concentrations of 1250 ppm and above, the extract outperformed the commercial inhibitor examined in this work. Further, the impact of alcohol addiction was found to improve inhibitor efficiency at lower concentrations, with a maximum value of 96.3% being recorded for 5% methanol. However, higher alcohol concentrations were found to negatively influence inhibition efficiency and alter general inhibitor characteristics.