Study of corrosion inhibition for mild steel in NaCl solution by propolis extract

Abstract

This paper studies the corrosion inhibition of X52 5L carbon steel in 0.51 mol dm-3 sodium chloride solution in the presence of propolis extract. The inhibition efficiency of propolis extract in a chloride solution was tested by its adding to the working solution and by making a solid propolis coating on the electrode surface. The possibility of corrosion inhibition in the presence of propolis in flow conditions as well as at different temperatures was investigated by electrochemical methods: potentiodynamic polarization method and electrochemical impedance spectroscopy. It was shown that propolis extract acts as a corrosion inhibitor of anodic type whose efficiency increases with increasing of temperature and with stirring of solution. The best protection is achieved by applying propolis coating in flow systems. The EIS method confirmed formation of a protective layer by adsorption of propolis extract on the electrode surface. The results of the FTIR, SEM and EDX surface tests are consistent with the results of electrochemical testing and suggest that propolis extract acts as a corrosion inhibitor of steel by forming a protective film on the electrode surface.