Corrosion behaviors of metals in biodiesel from rapeseed oil and methanol

Corrosiveness of Fuels During Storage Processes

“…The corrosive effect of biodiesel and bioethanol on copper, aluminum, carbon steel and stainless steel was also investigated in [8]. Immersion corrosion tests were carried out in accordance with ASTM G32-72 at 43ºC for two months.…”

“…Materials such as copper or carbon steel are readily oxidized. When exposed to biodiesel, metal oxides are formed, including: CuO, Cu 2 O, Fe 2 O 3 etc., which adhere less strongly to metal surfaces, compared with aluminum [8]. Later in the tests, surface analyses were carried out using SEM, EDS, XPS, and the concentrations of the respective ions in biodiesel before and after the corrosion tests were measured using AAS.…”

“…Examination indicates [8] that the black deposit may be composed of oxides or organic salts. On the other hand, the presence of organic salts and no iron oxide was observed on the carbon steel plate.…”

“…The increased content of carboxylic groups indicates oxidation of the biodiesel and the formation of carboxylic acids. Reactions between carboxylic acids and metal oxides produce organic salts which deposit upon the metal surfaces [8].…”

“…The corrosion products included mainly fatty acid salts, and metal oxides. It was also demonstrated that decomposition of biodiesel is catalyzed by elements such as copper and iron, creating an environment for corrosion of engine components [8].…”