Electrochemical corrosion of carbon steel exposed to biodiesel/simulated seawater mixture

The electrochemical corrosion of carbon steel exposed to a mixture of biodiesel and 3.5% NaCl solution simulated seawater was characterized using wire beam electrode (WBE) technique. Both optical images and in situ potential and current measurements showed that all the anodes and most cathodes formed in the water phase, but the cathodes were mainly located along the water/biodiesel interface. Due to oxygen concentration gradient and cross-phase ion transfer, low corrosion currents were also detected in biodiesel phase. Further anode reaction was partially blocked by iron rust, but the alkali residual in biodiesel may interact with corrosion and deteriorate biodiesel quality.

► Characterized the unique corrosion behaviour of carbon steel in the biodiesel/seawater environment. ► Illustrated the in situ anode and cathode distribution using a wire beam electrode approach. ► Elucidated the corrosion mechanisms based on ion transfer and oxygen concentration gradient.