Corrosion Inhibition Properties Of Acetone Extract Of Cassia Fistula Pods On Mild Steel And Aluminium In HCL Medium
ABSTRACT
Corrosion
inhibition efficiency of Cassia fistula pod
extract on mild in 0.5 M HCl solution was studied by gravimetric (weight loss)
and quantum mechanical methods. Thermodynamic parameters such as activation
energy, enthalpy, enthropy and Gibbs free energy of adsorption were determined.
Results showed that the inhibition efficiency increased significantly by up to
82.9 % and 57.36 % for mild steel and aluminum respectively with increase in
concentration of the inhibitor. However, the inhibition efficiency decreased
slightly with increasing temperature in the range 303-343 K. This is supported
by higher values of Kads (5.59-3.76) for mild steel and (1.10-0.73)
for aluminium. It is observed that at lower temperature, there is higher value
of Kads indicating that the inhibitor is more efficient at lower
temperatures. The
kinetic study shows that the inhibitory action follows a pseudo first order
kinetics with the concentration of the extract. This was further supported by
the thermodynamic parameters which reveal that the adsorption of both the
individual seed extracts and their blends onto the metal surface was
spontaneous, endothermic and followed physical adsorption mechanism. Cassia fistula
was identified to have phytochemicals of phenol, saponins, tannins, alkaloids,
terpenoids. These compounds are adsorbed by the surface of the metal, leading
to corrosion inhibition. The experimental data fitted best into the Langmuir and
Freundlich adsorption model for both mild steel and aluminium respectively at
various temperatures studied with linearity coefficient (R2) of
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification
iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables x
List of Figures xii
Abstract xv
CHAPTER 1: INTRODUCTION
1
1.1 Background
of Study 1
1.2 Statement
of the Problem 5
1.3 Justification of the Study 6
1.4 Aim of the Study 6
1.5 Scope
of the Study 7
2.2
Corrosion
Cells
and Reactions 8
2.3
Factors Responsible for Corrosion 9
2.4
Types of Corrosion 12
2.3.1.
Localized Corrosion 12
2.3.2
Uniform
surface corrosion 16
2.4
Corrosion in different media 18
2.4.1
Corrosion
in alkaline solution 18
2.4.2
Corrosion
in acid medium 19
2.4.3
Corrosion
in free organic liquid and gases 19
2.4.4
Corrosion
induced by bacteria 19
2.4.5
Corrosion
in moist environment 19
2.5
Consequences of Corrosion 20
2.5.1
Economic effects 20
2.5.2
Health effects 22
2.5.3
Safety effects 22
2.5.4
Technological effects 23
2.5.5
Cultural effects 23
2.6 Prevention
and Control of Corrosion 23
2.6.1
Applied coatings 23
2.6.2
Anodization 23
2.6.3
Galvanization 24
2.6.4
Biofilm coatings 25
2.7 Corrosion
Inhibition and Inhibitors 26
2.8
Types
of Inhibitors 26
2.8.1
Anodic (Passivating) inhibitors 29
2.8.2
Cathodic inhibitors 29
2.8.3
Organic inhibitors 32
2.8.4
Precipitating inhibitors
34
2.8.5
Green corrosion
inhibitors 35
2.9
Limitations and Advantages of Plant Extract
as Corrosion Inhibitors 39
2.10
Brief History of Cassia
fistula (a.k.a Golden shower tree ) 40
2.10.1
Medicinal uses 42
2.10.2
Other uses 43
2.10.3
Places where cassia
fistula can be found 44
2.10.4 Cassia
fistula as a corrosion inhibitor 45
CHAPTER 3:
MATERIALS AND METHODS 47
3.1 Materials 47
3.2 Methods 48
3.2.1
Determination of composition of metal coupons 48
3.2.2
Preparation of Cassia fistula seed extracts 49
3.2.3
Preparation of 0.5 M HCl 49
3.2.4
Phyto-chemical
analysis 50
3.2.5
Gravimetric techniques 53
3.2.6
Corrosion data 54
3.2.7
Adsorption isotherm study 55
3.2.8
Thermodynamic studies 57
3.2.9
Corrosion adsorption kinetics 58
3.2.10
Computational
method 59
CHAPTER 4: RESULTS AND DISCUSSION 62
4.1
Phytochemical
Analyses 62
4.2
Determination of Composition of Metal
Coupons 63
4.3
Analyses of FTIR Spectra 64
4.4
Effect of Concentration of Acetone Extract
of Cassia Fistula Pod on the
Corrosion
Rate of Metals (Mild Steel and Aluminium) and Inhibition
Efficiency
in 0.5 M HCl. 65
4.5
Effect of Temperature 70
4.6
Kinetic Consideration 75
4.7
Thermodynamics
78
4.7.1
Arrhenius
plots 78
4.7.2
Transition
state plots 80
4.8
Adsorption Considerations 83
4.8.1
Langmuir
adsorption isotherm 83
4.8.2
Freundlich adsorption
isotherm 86
4.9
Quantum Studies 89
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS 102
5.1 Conclusion 102
5.2 Recommendations 103
References
LIST OF TABLES
3.1 List of materials used for the experiments 47
3.2 List of equipment for the experiments 48
4.1:
Phytochemical test of extract of Cassia fistula pods 62
4.2
Chemical composition of studied
metal samples 63
4.3: Surface coverage and inhibition efficiency
of Cassia fistula pods
extracts on mild
steel metal at varying time 66
4.4:
Surface coverage and inhibition
efficiency of Cassia fistula pods
extracts on aluminium
metal at varying time 67
4.5:
Surface coverage and inhibition
efficiency of Cassia fistula pods
extracts
on mild steel metal at varying
temperature 72
4.6:
Surface coverage and inhibition
efficiency of Cassia fistula pods
extracts on aluminium
at varying temperature 73
4.7: Pseudo first order parameters for corrosion inhibition of mild steel
by
extract of Cassia
fistula pods 77
4.8: Pseudo first order parameters for corrosion inhibition of aluminium
by
extract of Cassia
fistula pods 77
4.9: Arrhenius parameters for the corrosion of mild steel and
aluminium
in acid containing various concentrations of the studied
inhibitor 79
4.10: Eyring-Transition state parameters for the corrosion of mild steel
in
acid containing various concentrations of
the studied inhibitor 82
4.11: Langmuir isotherm parameters for the
corrosion of mild steel and
aluminium in HCl medium containing various concentrations of the
studied inhibitor 85
4.12:
Freundlich isotherm parameters for the
corrosion of mild steel and
aluminium in HCl
medium containing various concentrations of the
studied
inhibitor 88
4.13
Electronic properties and global
reactivity descriptors of Fistulic acid,
Catechin and
Epicatechin 90
4.14:
Selected calculated Fukui functions and
Mulliken atomic charges of
Fistulic
acid 97
4.15
Selected calculated Fukui functions
and Mulliken atomic charges of
Catechin
98
4.16
Selected calculated Fukui functions
and Mulliken atomic charges of
Epicatechin 99
LIST OF FIGURES
2.1:
Schematic diagram of pitting corrosion
13
2.2:
A schematic diagram of crevice corrosion
14
2.3:
A schematic diagram of intergranular corrosion 14
2.4:
A schematic diagram of filiform corrosion 15
2.5:
A schematic diagram of uniform corrosion
16
2.6:
A schematic diagram of dtress corrosion
17
2.7: A potentiostatic polarization diagram of a solution with
electrochemical
behaviour of a metal in an anodic inhibitor 28
2.8:
The mechanism of the anodic
inhibitory effect 29
2.9: Potentiostatic polarization diagram 30
2.10: Theoretical potentiostatic polarization diagram 33
2.11: Illustration of the mechanism of actuation of
the organic inhibitor:
acting through adsorption of the inhibitor on the metal surface.
Where
the “Inh” represent the inhibitor
molecules. 33
2.12: Pictures of the Cassia fistula tree, pod and pulp 41
3.1: Pictures of separated pulp and pod 54
3.2: Pictures of metal immersed in a solution of HCl acid and
inhibitior 54
4.1:
FTIR Spectrum of the extract of Cassia fistula pods 64
4.2:
Effect of concentration of Acetone
Extract of Cassia fistula pods
on the corrosion rate of mild steel
in 0.5 M HCl 65
4.3:
Effect of concentration of acetone extract
of Cassia fistula pods on the
corrosion rate of aluminium in 0.5 M
HCl 66
4.4:
Effect of concentration of acetone
extract of Cassia fistula pods on
inhibition efficiency
on Mild Steel in 0.5M HCl at different contact times 69
4.5:
Effect of concentration of acetone
extract of Cassia fistula pods on
inhibition efficiency
on Aluminium in 0.5M HCl at different contact times 69
4.6:
Effect of concentration of acetone
extract of Cassia fistula pods on
inhibition efficiency
on Mild Steel in 0.5M HCl at different temperatures 71
4.7: Effect
of concentration of acetone extract of Cassia
fistula pods on
inhibition efficiency on aluminium in
0.5M HCl at different temperatures 71
4.8:
Pseudo first order plot for the
corrosion of mild steel in 0.5M HCl in the
absence and presence of
acetone extract of Cassia fistula pods
75
4.9:
Pseudo first order plot for the
corrosion of aluminium in 0.5M HCl
in the absence and
presence of acetone extract of Cassia
fistula pods 76
4.10: Arrhenius plots for the corrosion of mild steel in 0.5M HCl
containing
various concentrations of Cassia fistula pods extract 78
4.11: Arrhenius plots for the corrosion of aluminium in 0.5M HCl
containing
various concentrations of Cassia fistula pods extract 79
4.12: Eyring
Transition state plots for the corrosion of mild steel in 0.5
M HCl
containing various concentrations of Cassia
fistula pods extract 81
4.13: Eyring
Transition state plots for the corrosion of aluminium in 0.5
M
HCl containing various concentrations of Cassia
fistula pods extract 81
4.14: Langmuir
isotherm for the adsorption of the inhibitor on mild steel
surface in 0.5M HCl solution at
various temperatures 84
4.15: Langmuir
isotherm for the adsorption of the inhibitor on aluminuim surface
in 0.5 M HCl solution at various
temperatures 84
4.16: Freundlich
isotherm plots for the adsorption of the inhibitor on
mild steel surface in 0.5 M HCl
solution at various temperatures 87
4.17: Freundlich
isotherm plots for the adsorption of the inhibitor on
aluminuim surface in 0.5 M HCl
solution at various temperatures 87
4.18a: Optimized
structure of fistulic acid 92
4.18b: HOMO map of fistulic acid 92
4.18c: LUMO map of fistulic acid 92
4.18d: Electrostatic potential map of fistulic
acid 93
4.19a: Optimized structure of catechin 93
4.19b: HOMO map of catechin 94
4.19c: LUMO map of catechin 94
4.19d: Electrostatic potential map of catechin 95
4.20a: Optimized structure of epicatechin 95
4.20c: 4.20b:
HOMO map of epicatechin 96
4.20c:
LUMO map of epicatechin 96
0.0
OBETA, O (2023). Corrosion Inhibition Properties Of Acetone Extract Of Cassia Fistula Pods On Mild Steel And Aluminium In HCL Medium . Repository.mouau.edu.ng: Retrieved May 12, 2024, from https://repository.mouau.edu.ng/work/view/corrosion-inhibition-properties-of-acetone-extract-of-cassia-fistula-pods-on-mild-steel-and-aluminium-in-hcl-medium-7-2
OBETA, OBETA. "Corrosion Inhibition Properties Of Acetone Extract Of Cassia Fistula Pods On Mild Steel And Aluminium In HCL Medium " Repository.mouau.edu.ng. Repository.mouau.edu.ng, 31 Aug. 2023, https://repository.mouau.edu.ng/work/view/corrosion-inhibition-properties-of-acetone-extract-of-cassia-fistula-pods-on-mild-steel-and-aluminium-in-hcl-medium-7-2. Accessed 12 May. 2024.
OBETA, OBETA. "Corrosion Inhibition Properties Of Acetone Extract Of Cassia Fistula Pods On Mild Steel And Aluminium In HCL Medium ". Repository.mouau.edu.ng, Repository.mouau.edu.ng, 31 Aug. 2023. Web. 12 May. 2024. < https://repository.mouau.edu.ng/work/view/corrosion-inhibition-properties-of-acetone-extract-of-cassia-fistula-pods-on-mild-steel-and-aluminium-in-hcl-medium-7-2 >.
OBETA, OBETA. "Corrosion Inhibition Properties Of Acetone Extract Of Cassia Fistula Pods On Mild Steel And Aluminium In HCL Medium " Repository.mouau.edu.ng (2023). Accessed 12 May. 2024. https://repository.mouau.edu.ng/work/view/corrosion-inhibition-properties-of-acetone-extract-of-cassia-fistula-pods-on-mild-steel-and-aluminium-in-hcl-medium-7-2