Materials Sciences and Applications, 2015, 6, 1061-1070 Published Online November 2015 in SciRes. http://www.scirp.org/journal/msa http://dx.doi.org/10.4236/msa.2015.611105 How to cite this paper: Al-Saadie, K.A., Abas, H.A. and Almashhdani, H.A.Y. (2015) Corrosion Protection of Iron Alloy Using Peganum harmala Extract as Inhibitor in Acidic Solution. Materials Sciences and Applications, 6, 1061-1070. http://dx.doi.org/10.4236/msa.2015.611105 Corrosion Protection of Iron Alloy Using Peganum harmala Extract as Inhibitor in Acidic Solution Khulood Abid Al-Saadie 1* , Hayfaa Ameer Abas 1 , Haider Abdulkareem Yousif Almashhdani 2 1 Department of Chemistry, College of Science, Baghdad University, Baghdad, Iraq 2 Department of Dentistry, Al-Rasheed University College, Baghdad, Iraq Received 18 October 2015; accepted 24 November 2015; published 27 November 2015 Copyright © 2015 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract This work describes the inhibition effect of different concentration of an aqueous extracted of Pe- ganum harmala seed on the corrosion of carbon steel in 1 M H2SO4 solution using potentiostatic polarization techniques at the temperature range (298 - 328) K. The result showed that the inhibi- tion efficiency increased with increasing of extract inhibitor concentration and temperature. The adsorption of inhibitor on carbon steel surface was fit into Langmuir adsorption isotherm. Kinetic and thermodynamic parameters governing the corrosion and the adsorption process were calcu- lated and discussed. Keywords Corrosion, Carbon Steel, Seed, Peganum harmala, Acidic Solution 1. Introduction Corrosion is recognized as the number one life limiting plant degradation mechanism [1] and exhibited by most engineering materials in nearly all environments [2]. There are numerous methods for controlling the corrosion of metals but the use of inhibitors is still one of the best methods of protecting metals against corrosion. Many organic compounds are used as corrosion inhibitors for metals in acidic environments [3]. Corrosion inhibitors are substance that when adsorbed onto the metal-solution interface, blocks the corrosive material from coming into contact with metal. A number of heterocyclic compounds containing nitrogen, oxygen and sulphur either in the aromatic or in long chain carbon system have been reported to be effective inhibitors [4]. Extracts of various * Corresponding author.