Ph.D Thesis of Alfred I Onen

231 Pages·2014·11.21 MB·English

by  Alfred I. Onen

KINETIC STUDIES OF SELECTED CORROSION INHIBITORS OF
ALUMINIUM AND MILD STEEL IN ACID MEDIUM

ALFRED IKPI ONEN
BSc CHEM (CALABAR); MSc PHY. CHEM (IBADAN)
(PGNS/UJ/0019/04)

A Thesis in the Department of CHEMISTRY,
Faculty of Natural Sciences,
Submitted to the School of Postgraduate Studies,
University of Jos, in partial fulfillment of the requirements for the award
of the degree of DOCTOR OF PHILOSOPHY IN
PHYSICAL CHEMISTRY of the
UNIVERSITY OF JOS

NOVEMBER, 2010.
ii

DECLARATION

I hereby declare that this work is the product of my own research efforts; undertaken
under the supervision of Prof. B.T.Nwufo and has not been presented elsewhere for the
award of a degree or certificate. All sources have been duly distinguished and
appropriately acknowledged.

_______________________
ALFRED IKPI ONEN
PGNS/UJ/0019/04
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iv

ACKNOWLEDGEMENT
I thank the ALMIGHTY GOD for the invaluable guidance and protection over me
during the period of my study. With HIM everything has been made possible.
To HIM I give glory.
I am indeed very grateful to my able and indefatigable supervisor, Prof. B.T.Nwufo,
for his guidance throughout the duration of the research. His erudite criticisms,
encouragement and untiring support made this research work a success.
I sincerely acknowledge the contributions of Professors K.I.Ekpenyong, M.M
Ekwenchi, T.Shambe, Y.N.Lohdip, E.A.Adelakun and, Dr S.J.Salami towards the
improvement of this work. The advice you offered me and discussion made on the
subject matter will never be forgotten.
My profound gratitude also goes to the Management and Senate of Adamawa State
University (ADSU), Mubi for granting me a Study Fellowship and for providing most of
the equipment and necessary facilities that enabled me to carry out my research without
hindrances. I am equally indebted to my colleagues in the Department of Chemistry
(ADSU) who made it possible for me to be released for the programme. I am particularly
grateful to the Laboratory staff of the Department especially Mal. Abdulhamid Umar,
Iliya Kaigama and Saminu Abdulmalik for their tireless assistance towards the use of
some equipment (UV/Visible, I-R Spectrophotometers etc) for the research that resulted
to this progress report.
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My sincere thanks are also due to the Head and Staff of Chemistry Department,
University of Jos for providing me with a conducive atmosphere to carry out my study.
I wish to acknowledge my colleagues and friends, particularly D.A.Apagu, O.A.Anyebe,
Dr O.N.Maitera, Dr J.T.Barminas, S.A.Mamuru, M.Z.Zaruwa, A.A.Abede, D.Zira, Dale
M.Waida, P.S.Wakshama, Stephen Dayya, Alfred.D.Mshelia, James.A.Awolade, Samuel
Chima, Dr Iwara Iwara, Dr Ibrahim Kwari and Dr Sani Yerima for their companion,
encouragement and assistance throughout the period of this study.
I owe a lot of thanks to my family- my lovely wife, Jummai A.Onen, Mfawayobase,
Enoabasi, Williams and Ikpi Jnr for their patience and affection. I will like to express my
heartfelt gratitude to my parents- Chief Onen Okoi and Mrs. Arit Onen Okoi as well as
my brothers and sisters- Essien N. Ikoi, late SP. Michael Eyum (Rtd), Insp. Okoi Onen,
Godson E.Onen, Veronica O. Utum and Diana Onen for their encouragement, continuous
prayers and support to me.
Finally, I appreciate the contributions of all those whose names are not recorded in
this progress report. I thank them all.
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DEDICATION

To my wife, Jummai A.Onen, for her love, prayers, understanding and financial
support and to my beloved children- Mfawayobase, Enoabasi, Williams and Ikpi Jnr. for
their patience and moral support throughout the period of the Ph.D programme.
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TABLE OF CONTENTS
TITLE PAGE
TITLE PAGE … … …. … … … … … ... i
DECLARATION … … …. … … … … … ... ii
CERTIFICATION … … …. … … … … … ... iii
ACKNOWLEDGEMENT… … …. … … … … … iv
DEDICATION… … …. … … … … … ... vi
TABLE OF CONTENTS … … …. … … … … … vii
LIST OF TABLES… … …. … … … … … ... xi
LIST OF FIGURES … … …. … … … … … xiii
LIST OF APPENDICES … … … … … … … … xvii
LIST OF ABBREVIATIONS /ACRONYMS … … …… … xviii
ABSTRACT … … …. … … … … … ... xix

CHAPTER ONE
INTRODUCTION
1.0 BACKGROUND OF THE STUDY… … …. … … … 1
1.1 STATEMENT OF THE PROBLEM … … …. … … … 10
1.2 OBJECTIVES OF THE STUDY… … …. … … … 12
1.2.1 Main Objective … … … … … … … … 12
1.2.2 Specific Objectives … … … … … … … 12
1.3 THE SCOPE AND LIMITATIONS OF THE STUDY … … …. 13
1.4 THE SIGNIFICANCE OF THE STUDY… … …. … … 14
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CHAPTER TWO
LITERATURE REVIEW
2.0 CONCEPT OF CORROSION… … …. … … … … 15
2.1 CORROSION AS A REACTION AT A METAL/ENVIRONMENT
INTERFACE… … …. … … … … … ... 17
2.1.1 Environments in Corrosion Process… … …. … … 20
2.1.2 Metals… … …. … … … … … ... 30
2.2 TYPES OF CORROSION… … …. … … … … 35
2.3 EFFECTS OF CORROSION ON MATERIALS
(METALS/NON-METALS) … … … … … … … 37
2.4 CORROSION INHIBITION/PROTECTION… … …. … … 40
2.5 CORROSION INHIBITORS… … …. … … … … 47
2.5.1 Inhibitors of Plant Origin … … …. … … … … 47
2.5.2 Organic Inhibitors… … …. … … … … … 49
2.5.3 Inorganic Complexes as Inhibitors… … …. … … … 52
2.5.4 Use of Dyes as Inhibitors… … …. … … … … 55
2.6 EFFECT OF HALIDES ON CORROSION INHIBITION… … …. 57
2.7 EFFECT OF INHIBITOR CONCENTRATION AND TEMPERATURE
ON CORROSION INHIBITION… … …. … … … 59
2.8 EFFECT OF MOLECULAR STRUCTURE OF INHIBITOR ON
CORROSION INHIBITION… … …. … … … … 61
2.9 INHIBITION MECHANISM… … …. … … … … 63
2.10 KINETICS AND THERMODYNAMICS OF CORROSION
INHIBITION … … … … … … … … … 66
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CHAPTER THREE
MATERIALS AND METHODS
3.0 MATERIALS… … …. … … … … … ... 68
3.1 EQUIPMENT/APPARATUS… … …. … … … … 68
3.2 MATERIALS AND REAGENTS… … …. … … … 69
3.3 MATERIALS PREPARATION… … …. … … … 69
3.3.1 Extraction of CSL Leaf Extract… … …. … … … 70
3.3.2 Preparation of Inhibitor Solutions… … …. … … … 70
3.4 ABSORBANCE DIFFERENCE MEASUREMENT … … …. … 71
3.5 KINETIC STUDIES… … …. … … … … … 74
3.6 SCREENING OF PLANT SECONDARY METABOLITES IN
CASSIA SIAMEA LAM LEAF EXTRACT… … … … … 74
3.6.1 Test for Alkaloids… … …. … … … … … 74
3.6.2 Test for Phenols… … …. … … … … … 74
3.6.3 Test for Saponins… … …. … … … … … 75
3.6.4 Test for Tannins… … …. … … … … … 75
3.6.5 Test for Flavonoids… … …. … … … … … 75
3.6.6 Infra-Red Measurement… … …. … … … … 75
CHAPTER FOUR
RESULTS… … …. … … 76
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CHAPTER FIVE
DISCUSSION
5.0 EFFECT OF CORRODENT CONCENTRATION AND TEMPERATURE
ON ALUMINIUM AND MILD STEEL CORROSION… … …. 145
5.1 EFFECT OF INHIBITOR CONCENTRATION ON INHIBITION
EFFICIENCY… … …. … … … … … ... 145
5.2 EFFECT OF HALIDE IONS CONCENTRATION ON ALUMINIUM AND
MILD STEEL IN H SO … … …. … … … … 147
2 4
5.3 INFLUENCE OF INHIBITOR-HALIDE IONS CONCENTRATION ON
ALUMINIUM AND MILD STEEL CORROSION… … …. … 148
5.4 KINETIC AND THERMODYNAMIC CONSIDERATIONS OF THE
RESULTS… … …. … … … … … ... 149
5.5 ADSORPTION CONSIDERATIONS OF THE RESULTS… … …. 152
5.6 SYNERGISM CONSIDERATIONS… … …. … … … 155
5.7 EFFECT OF MOLECULAR STRUCTURE OF INHIBITORS ON
CORROSION INHIBITION OF ALUMINIUM AND MILD STEEL … 156
5.8 MECHANISM OF INHIBITION OF ALUMINIUM AND MILD STEEL
CORROSION BY CASSIA SIAMEA LAM (CSL) LEAF EXTRACT… … 160

5.9 COMPARISON OF INHIBITION EFFECTIVENESS OF THE INHIBITORS
ON ALUMINIUM AND MILD STEEL CORROSION… … …. 161
5.10 CONCLUSION (S) … … …. … … … … … 163
5.11 RECOMMENDATIONS … … … … … … … 164
5.12 SUMMARY OF FINDINGS … …. … … … … 165
CONTRIBUTION TO KNOWLEDGE … … …. … … … 166
REFERENCES… … …. … … … … … ... 167
APPENDICES …. … … … … … … … 181