S.A. Umorena, I.B. Obota,*,E.E. Ebensob, N. Obi-Egbedic
aDepartment of Chemistry, Faculty of Science, University of Uyo, Uyo, Nigeria
bPhysical Chemistry Unit, Department of Pure and Applied Chemistry, University of Calabar, Calabar, Nigeria
Department of Chemistry and Chemical Technology, National University of Lesotho, P.O.Roma 180, Lesotho, Southern Africa
cPhysical Chemistry unit, Department of Chemistry, University of Ibadan, Ibadan, Nigeria
Received 24 April 2007; accepted 13 June 2007
]]>Abstract
The inhibitive effect of exudate gum from Dacroydes edulis in the corrosion of aluminium in HCl solutions was studied using weight loss and thermometric methods at 30-60 oC. The results reveal that the exudate gum acts as an inhibitor for corrosion of aluminium in HCl solution. The inhibition efficiency increases with an increase in the concentration of the exudate gum but decreases with increase in temperature. The Temkim adsorption isotherm was tested for its fit to the experimental data. The result confirms that the corrosion inhibition of the exudate gum from DE is attributed to the adsorption of molecules of phytochemicals present in the exudate gum on the surface of the metal. The free energies and equilibrium constant for the adsorption process were determined. A mechanism of physical adsorption is proposed.
Keywords: corrosion inhibition, aluminium, Dacroydes edulis, adsorption, Temkin isotherm.
Texto disponível em PDF
Full text only in PDF format
References
1. E.E. Oguzie, Pigment & Resin Tech. 34(6) (2005) 321. [ Links ]
2. E.E. Oguzie, A.I. Onuchukwu, P.C. Okafor, E.E. Ebenso, Pigment & Resin Tech. 35(2) (2006) 63.
3. C.A. Loto, A.I. Mohammed, Corros. Prev. Control 47 (2) (2000) 50.
4. G. Gunasekeran, L.R. Chauhan, Electrochimica Acta 49 (25) (2004) 4387.
5. M. Kliskic, J. Radosevic, S. Gudic, V. Katalinic, J. Appl. Electrochem. 30 (2000) 823.
6. G.O. Avwiri, F.O. Igbo, Mater. Lett. 57 (2003) 3705.
7. S. Martinez, I. Stern, J. Appl. Electrochem. 33 (2001) 1137.
8. H. Ashassi-Sorkhabi, D. Seifzadeh, Int. J. Electrochem. Sci. 1 (2006) 92.
9. P.C. Okafor, U.J. Ekpe, E.E. Ebenso, E.M. Umoren, K.E. Leizou, Bull. Electrochem. 21(8) (2005) 347.
10. A. Bouyanzer, B. Hammouti, L. Majidi, Mater. Lett. 60 (2006) 284.
11. A.Y. El-Etre, Corros. Sci. 40 (11) (1998) 1845.
]]> 12. S. Rajendran, S. Shanmugapriya, T. Rajalakshmi, A.J. Amal Raj, Corrosion 61 (7) 685.13. A.Y. El-Etre, M. Abdallah, Z.E. El-Tantawy, Corros. Sci. 47 (2) 385.
14. S.P. Ramesh, K.P. Vinod, G.H. Sethhuraman, Bull. Electrochem. 17 (3) (2001) 141.
15. C.A. Loto, A.I. Mohammed, R.O. Loto, Corros. Prev. Control, 50 (30) (2003) 107.
16. E.E. Oguzie, Pigment & Resin Tech. 35(6) (2006) 334.
17. E.E. Ebenso, U.J. Ibok, U.J. Ekpe, S.A. Umoren, E. Jackson, O.K. Abiola, N.C. Oforka and S. Martinez, Trans. SAEST 39 (2004) 117.
18. M.G. Sethuraman, P.B. Raja, Pigment & Resin Tech. 34(6) (2005) 327.
19. A. Bouyanzer, B. Hammouti, Pigment & Resin Tech. 33(5) (2004) 287.
20. A. Chetouani, B. Hammouti, M. Benkaddour, Pigment & Resin Tech. 33(1) (2004) 26.
21. A.Y. El-Etre, Appl. Surf. Sci. 252 (2006) 8521.
]]> 22. A.Y. El-Etre, Corros. Sci. 45 (2003) 2485.23. M. Abdallah, Portugaliae Electrochimica Acta 22 (2004) 161.
24. M.I. Awad, J. Appl. Electrochem. 36 (2006) 1163.
25. E.E. Oguzie, Corros. Sci. 49 (2007) 1527.
26. S.A. Umoren, I.B. Obot, E.E. Ebenso, P.C. Okafor, O. Ogbobe, E.E. Oguzie, Anti-Corros. Methods and Mater. 53(5) (2006) 277.
27. S.J. Zakvi, G.N. Mehta, Trans. SAEST 23 (1988) 4.
28. S. Martinez, Mater. Chem. Phys. 77 (2002) 97.
29. A.Y. El-Etre, Z. El-Tantawy, Portugaliae Electrochimica Acta 24(2006) 347.
30. E.T. Ayuk, B. Duguma, S. Franzel, J. Kengue, M. Mollet, T. Tiki-Manga, P. Zekeng, Economic Botany 53(3) (1999) 292.
31. U.J. Ekpe, E.E. Ebenso, B.S. Antia, West. Afri. J. Biol. Appl. Chem. 41 (1999) 16.
]]> 32. Corrosion Basics, “An Introduction”, National Association of Corrosion Engineers (NACE) (1984) 34.33. D.A. Jones, “Principles and Prevention of Corrosion”, 2nd Edition, Printice-Hall Inc., Upper Saddle River, NJ USA, 1996 Pp 31-34.
34. B.N. Oza, R.S. Sinha, Trans. SAEST 17(1) (1982) 281.
35. A.A. Shams Eldin, M.G.A. Kherdr, Metalloberft 25 (1992) 200.
36. A.Y. El-Etre, Corros. Sci. 43 (2001) 1031.
37. P. Atkins, J. de Paula, Physical Chemistry, Oxford University Press, Oxford (2002) 871.
38. I. Ita, O.E. Offiong, Mater. Chem. Phys. 70 (2001) 330.
39. E.E. Ebenso, P.C. Okafor, O.E. Offiong, B.I. Ita, U.J. Ibok, U.J. Ekpe, Bull. Electrochem. 17 (2001) 459.
40. S.M. Mayanna, J. Electrochem. Soc. 122 (1973) 252.
41. L. Tang, X. Li, Y. Si, G. Mu, G. Liu, Mater. Chem. Phys. 95 (2006) 29.
]]>* Corresponding author. E-mail address: proffoime@yahoo.com
]]>