Study On The Synergistic Effects Between Chitosan Inhibitor And Cathodic Protection To Pipeline Steel

Seawater has been used more in power plants constructed at seaside in China to decrease loss of water sources. Green, economical and suitable methods is necessary to ensure the safety of seawater cooling systems. Application of corrosion inhibitors and cothodic protection are very preventative methods which have been reported to be helpful in cooling systems. Carboxymethyl chitosan(CMCS) is a kind of chitosan derivative with better water solubility. It is nontoxic and biodegradable. The application of CMCS and cathodic protection can effectively improve the protection effect and reduce the corrosion rate.In this study, the inhibition efficiency of carboxymethyl chitosan and its composite inhibitor for steel X70 was studied using electrochemical test, scanning electron microscopy, XRD and FTIR. The results showed that the corrosion efficiency increased with the concentration of CMCS and reached 43.4% at the concentration of 0.5g?L-1. With further increase in concentration, the efficiency didn’t change very much. The addition of Na2WO4 in CMCS inhibitor acted well in reducing corrosion rate. Corrosion efficiency reached 57.4% at the composite of 0.25 g?L-1 CMCS and 0.1g?L-1Na2WO4. FTIR, SEM and XRD analysis showed that CMC adsorb on the metal surface and formed a protective dense film.Combined inhibitor and cathodic protection have a synergistic effect on the protection of X70 pipeline steels. Calcareous deposit only forms on the metal surface in blank seawater, but cannot form in the presence of CMCS and Na2WO4, and there was no sign of corrosion.