Abstract

The inhibition efficiency of aqueous extract of propolis on the corrosion of carbon steel in 35 ppm aluminum sulfate and 10 ppm chloride solution was investigated by weight loss and electrochemical measurements. The corrosion rate of carbon steel and the inhibition efficiency of the propolis were calculated. The results obtained showed that propolis could serve as an effective inhibitor for the corrosion of carbon steel in aqueous media. Inhibition was found to increase with increasing concentration of the extract. The inhibitive action of propolis is discussed on the basis of adsorption of stable complex at the carbon steel surface. Theoretical fitting of different isotherms, Langmuir was tested to clarify the nature of adsorption. Potentiodynamic polarization curves revealed that this extract acts as a mixed type inhibitor and the inhibition efficiency of up to 92% can be obtained.

Key words: Corrosion inhibition, propolis extract, carbon steel, 35 ppm aluminum sulfate and 10 ppm chloride solution.