ABSTRACT

The present study examined the adsorption and corrosive inhibitive properties of neem root on mild steel in alkaline and acidic media. The objectives of the study were to extract liquid from Azadirachta indica (neem) root; inhibit the corrosive mild steel in H₂SO₄ and NaOH solutions and examine the effects of inhibitor and corrodent concentration on inhibitor efficiency. The neem root was obtained from the neem trees in Michael Okpara University of Agriculture, Umudike. The stock solution of the extract obtained was used in preparing 0.5N, 1.0N H₂SO₄ and NaOH for mass loss method and 3N, 4N, and 5N H₂SO₄ and NaOH for thermometric analysis, respectively. The weight loss experiment was carried out at 30 and 60⁰C. The result showed that the corrosion rate was found to increase with increase in the corrodent concentration and also with increase in temperature. The extract from the neem root was found to be an inhibitor for mild steel in 0.5 M H₂SO₄ and NaOH. However, the metal was found to corrode faster in NaOH than in H₂SO₄ solution. Inhibition efficiency increased with increase in inhibitor concentration. It was therefore recommended that natural plant extracts such as neem root extract can be utilized as a corrosion agent against corrosion in both acidic and alkaline environment.

TABLE OF CONTENTS

Cover page

Declaration                                                                                                                              i

Certification                                                                                                                            ii

Dedication                                                                                                                              iii

Acknowledgment                                                                                                                   iv

Table of contents                                                                                                                    v

List of tables                                                                                                                           vii

List of figures                                                                                                                         viii

Abstract                                                                                                                                  ix

 

 

CHAPTER ONE

INTRODUCTION

1.1       Background of Study                                                                                                1

1.2       Statement of problem                                                                                                3

1.3       Aim and Objectives of Study                                                                                    4

1.4       Justification of Study                                                                                                4

1.5       Scope of the Study

 

 

CHAPTER TWO

LITERATURE REVIEW

2.1       Corrosion                                                                                                                    6

2.2       Corrosion Inhibitors                                                                                                    6

2.3       Plant based corrosion inhibitors                                                                                  8

2.3.1    Solvent effect                                                                                                            10

2.3.2    Temperature and Immersion time effect                                                                   11                 2.3.3    Adsorption mechanism                                                                                             12                 

2.4       Extraction                                                                                                                  12

2.4.1    Inhibitors Extraction                                                                                                  16                                                      

 

 

CHAPTER THREE

MATERIALS AND METHODS

3.1       Materials                                                                                                                     19

3.2       Extraction                                                                                                                   19

3.3       Gasometric method                                                                                                     19

3.4       Thermometric method                                                                                                 20

3.5       Gravimetric method (weight loss experiment)                                                            21

CHAPTER FOUR

RESULTS AND DISCUSSION

4.1.      Effect of corrodent concentration                                                                               22

4.2.      Effects of inhibitor concentration on inhibition efficiency                                        24

4.3.      Products composition of Pyrolytic oil                                                                        33

4.4.      Higher Heating value of Char                                                                                     33

 

 

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.1       Conclusion                                                                                                                   29

5.2       Recommendation                                                                                                        29

 

 

REFERENCES

 

 

 

 

 

 

 

 

 

 

 

LIST OF TABLES

Table 4.1:        Values of corrosion rate (mpy), inhibition efficiency (I %) and degree        

of surface coverage (θ) for mild steel corrosion for neem root in 0.5 M

H₂SO₄ at 30 ^oC and 60^oC                                                                                25

 

Table 4.2:        Values of corrosion rate (mpy), inhibition efficiency (I %) and degree

of surface coverage (θ) for mild steel corrosion for neem root in 0.5 M

NaOH at 30 and 60^oC                                                                                    26

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIST OF FIGURES

Figure 2.1.       Basic parts of a plant and their common active compounds                          10

Figure 2.2        Diagrams of common extraction methods                                                      14

Figure 3.1a:     Mild steel coupons before adsorption                                                              21

Figure 3.1b:     Mild steel coupons after adsorption                                                                 21

Figure 4.1a:     Plot of corrosion rate against corrodent concentration for mild steel

corrosion in H₂SO₄ at 30⁰C and 60⁰C                                                             23

Figure 4.1b:     Plot of corrosion rate against corrodent concentration for mild steel             23

 corrosion in NaOH at 30⁰C and 60⁰C

Figure 4.2a:     Plot of weight loss against time for mild steel corrosion in 0.5 M H₂SO₄       24

                        in the absence and presence of extract at 30⁰C

Figure 4.2b:     Plot of weight loss against time for mild steel corrosion in 0.5 M H₂SO₄      25

in the absence and presence of extract at 60⁰C

Figure 4.3a:     Plot of inhibition efficiency (% I) against extract concentration for mild      27

 steel in H₂SO₄ at 30⁰C and 60⁰C

Figure 4.3b:     Plot of inhibition efficiency (% I) against extract concentration for mild      27

steel in H₂SO₄ at 30⁰C and 60⁰C