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E-Journal of Chemistry
Volume 8, Issue 4, Pages 1708-1713

The Effects of Cassia Siamea Lam. Root Extract on the Corrosion and Kinetics of Corrosion Process of Copper in Alkaline Solutions

A. I Onen,1 B. T. Nwufo,2 and E. E. Ebenso3

1Department of Chemistry, Adamawa State University, P.M.B-25, Mubi, Nigeria
2Department of Chemistry, University of Jos, Plateau State, Nigeria
3Department of Chemistry, North West University (Mafikeng Campus), Private Bag X2046, Mmabatho-2735, South Africa

Received 1 March 2011; Accepted 22 April 2011

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The effect of Cassia siamea lam. (CSL) root extract as a corrosion inhibitor of copper in 0.50 M NaOH solutions was investigated using absorbance difference technique at 30 °C and 40 °C. CSL root extract inhibited the corrosion of copper in 0.50 M NaOH solutions and the inhibition efficiency (% IE) increased to a maximum of 78.3±2.3% with increasing concentration of the extract but decreased with increasing temperature. The adsorption of CSL root extract on copper surface followed the Langmuir adsorption model with the average heat of adsorption, Qads and free energy of adsorption, ΔGads of -8.98 kJmol-1 and -8.70 kJmol-1 respectively. A kinetic treatment of the data revealed a first order kinetics with respect to copper in the presence and absence of the extract.