Effect of extracellular polymeric substances isolated fromVibrio natriegenson corrosion of carbon steel in seawater

Extracellular polymeric substances (EPS) are isolated from marine Vibrio natriegens (V. natriegens) by a cation exchange resin method. The influences of EPS concentration and corrosion time on the corrosion of carbon steel in seawater are investigated. The results demonstrate that EPS are capable of forming a protective film on the surface of carbon steel in seawater, which retards the diffusion of dissolved oxygen and inhibits the reduction of oxygen on the cathode. In addition, the efficiency of corrosion inhibition increases with an increase in the amount of added EPS during the initial state (the first 3 days); however, excess EPS (exceeding 300 mg L−1) in seawater significantly accelerates the corrosion of carbon steel over the long term (10 days) due to the binding power of EPS with Fe ions.