Bacterial exopolysaccharides for corrosion resistance on low carbon steel

Corrosion is a global issue that affects safety and economics. There is an increasing demand for bio-based polymers for industrial applications and production of polymers by micro-organisms is especially attractive. This work reports on the electrochemical and physical properties of exopolysaccharides produced from lactic acid bacteria and their suitability as anti-corrosive coatings. Bacterial exopolysaccharide coatings protected low carbon steel from corrosion by reducing ionic diffusion rates and maintaining a relatively passive metal-coating interface. The data suggest the kinetics of film deposition are fast (< 5 min) and there is little excess (loosely bound) material when hydrated. Measurements show thin (50 nm) coatings that when exposed to water exhibit self-repairing phenomenon. The corrosion protection offered by the coatings is reported as the corrosion rate calculated from the corrosion current obtained by electrochemical impedance and polarization spectroscopy. (c) 2017 Wiley Periodicals, Inc.