Impact of moisture on the corrosion behavior of copper and mild carbon steel in corn biodiesel

Abstract

Abstract Presence of moisture is very important for vegetable oils and for corresponding biodiesel because it may cause some problems or accelerate some issues that cannot be ignored. One of the main hindrances of biodiesel is its hygroscopic nature, which accelerates the corrosion of the fuel system of the engines. Thus, this study aims to investigate the effects of moisture on corn biodiesel and its susceptibility to corrosion on different automotive materials such as copper and mild carbon steel. Static immersion tests in corn biodiesel (B100) with different water concentrations (100 ppm, 500 ppm, and 700 ppm) were carried out at 90°C for 1200 h, and the results were compared to that of commercial diesel fuel (B0). After immersion tests, the surface morphology was studied by scanning electron microscopy (SEM), and corrosion products were detected by X-ray diffraction (XRD). The total acid number (TAN) was used to evaluate the changes in acidity of fuel, before and after immersion tests. It was found that under experimental conditions, corn biodiesel is more corrosive than diesel fuel, and the moisture from corn biodiesel has a strong influence on corrosion rate on metals. Copper is more susceptible to corrosion in corn biodiesel than mild carbon steel.