Natural Products as a Source of Environmentally Friendly Corrosion Inhibitors: The Case of Gum Exudate from Acacia seyal var. seyal

 

 

J. Buchweishaija,*G.S. Mhinzi

 

Chemistry Department, University of Dar es Salaam, P.O. Box 35061, Dar es Salaam, Tanzânia

Received 6 June 2007; accepted 26 September 2007

 

 

Abstract

The inhibitive effect of the gum exudate from Acacia seyal var. seyal on the corrosion of mild steel in drinking water was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The results obtained show that gum exudates could serve as effective inhibitors for the corrosion of steel in drinking water network. The percentage inhibition increases with increasing the concentration of the gum at 30 ^oC. The percentage inhibitor efficiency above 95 % was attained at gum concentration ³400 ppm. The corrosion rates of steel and inhibition efficiencies of the gum exudates obtained from impedance and polarization measurements were in good agreement. Potentiodynamic polarization studies clearly reveal that the gum behaves predominantly as an anodic inhibitor. The study also shows that the inhibition efficiency was insignificantly affected by the temperature rise of the medium.

Keywords: corrosion, inhibitor, acacia seyal, gum exudates, mild steel.

 

 

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* Corresponding author. E-mail address: buchwe@chem.udsm.ac.tz