Electrochemistry and Materials Science Research Laboratory, Department of Chemistry, Federal University of Technology, PMB 1526, Owerri, Nigeria
Oguzie, E.E., Electrochemistry and Materials Science Research Laboratory, Department of Chemistry, Federal University of Technology, PMB 1526, Owerri, Nigeria
Corrosion inhibition of mild steel in 2 M HCl and 1 M H2SO4 by extracts of selected plants was investigated using a gasometric technique at temperatures of 30 and 60 °C. The studied plants materials include leaf extracts Occimum viridis (OV), Telferia occidentalis (TO), Azadirachta indica (AI) and Hibiscus sabdariffa (HS) as well as extracts from the seeds of Garcinia kola (GK). The results indicate that all the extracts inhibited the corrosion process in both acid media by virtue of adsorption and inhibition efficiency improved with concentration. Synergistic effects increased the inhibition efficiency in the presence of halide additives. Inhibition mechanisms were deduced from the temperature dependence of the inhibition efficiency as well as from assessment of kinetic and activation parameters that govern the processes. Comparative analysis of the inhibitor adsorption behaviour in 2 M HCl and 1 M H2SO4 as well as the effects of temperature and halide additives suggest that both protonated and molecular species could be responsible for the inhibiting action of the extracts. © 2008 Elsevier Ltd. All rights reserved.
Acids; Adsorption; Concentration (process); Corrosion; Corrosion prevention; Electrochemical corrosion; Steel; A. Acid solution; A. Mild steel; Acid corrosions; Acid medias; Activation parameters; Adsorption behaviours; Azadirachta indica; C. Acid corrosion; C. Acid inhibition; Comparative analysis; Corrosion inhibitions; Corrosion processes; Effects of temperatures; Halide additives; Inhibition efficiencies; Inhibition mechanisms; Inhibitive effects; Kinetic; Leaf extracts; Mild steels; Molecular species; Plant extracts; Protonated; Synergistic effects; Temperature dependences; Extraction