A COMPARATIVE STUDY ON THE CORROSION OF STAINLESS STEEL IN 1M HYDROCHLORIC ACID USING Tamarindus indica (TAMARIND) AND Terminalia catappa (TROPICAL ALMOND) LEAVES EXTRACTS AS INHIBITORS
ABSTRACT
The effectiveness of Terminalia catappa (tropical almond) and Tamarindus indica (tamarind) as corrosion inhibitors for stainless steel in 1M hydrochloric acid at 30°C, 40°C and 50°C was investigated in this research. The gravimetric method of analysis was employed for 20 days at a 4-day interval using 0.9, 1.1 and 1.3g/15mL of Terminalia catappa leaves extracts and 1.4 and 2.3g/15mL of Tamarindus indica leaves extracts. The results showed that the two extracts acted as good inhibitors for stainless steel. The corrosion rate, surface coverage, inhibition efficiency, inhibition mechanism and the effects of temperature were analyzed. The results showed that the highest inhibition efficiency for tamarind was 97.71% at 30°C using 2.4g/15mL, while the lowest was 87.95% with 2.3g/mL at 30°C.The highest efficiency for tropical almond was 97.89% with 1.3g/mL at 50°C and the lowest was 88.7% with 0.9g/mL at 50°C. The isotherms showed that tropical almond acted as a mixed type inhibitor, although predominantly by physisorption. The effects of temperatures also confirmed that tamarind adsorbed by physisorption only.
TABLE OF CONTENTS
COVER PAGE………………………………………………………………………………………………………………….. i
CERTIFICATE OF STAMENT…………………………………………………………………………………………… ii
ABSTRACT……………………………………………………………………………………………………………………. iii
DEDICATION………………………………………………………………………………………………………………… iv
ACKNOWLEDGEMENT………………………………………………………………………………………………….. v
TABLE OF CONTENTS…………………………………………………………………………………………………… vi
LIST OF TABLES………………………………………………………………………………………………………….. viii
LIST OF FIGURES………………………………………………………………………………………………………….. ix
- CHAPTER ONE:INTRODUCTION…………………………………………………………………………………… 1
- PROBLEM STATEMENT PROBLEM STATEMENT………………………………………………….. 1
- MOTIVATION……………………………………………………………………………………………………… 2
- AIMS AND OBJECTIVES……………………………………………………………………………………… 3
- SCOPE OF PROJECT…………………………………………………………………………………………….. 3
- RESEARCH OVERVIEW………………………………………………………………………………………. 4
- CORROSION…………………………………………………………………………………………….. 4
- TYPES OF CORROSION…………………………………………………………………………….. 5
- DRY OR DIRECT CHEMICAL CORROSION……………………………………… 5
- ELECTROCHEMICAL OR WET CORROSION…………………………………… 6
- CORROSION CONTROL……………………………………………………………………………. 7
- INORGANIC INHIBITORS……………………………………………………………… 8
- ORGANIC INHIBITORS………………………………………………………………….. 8
- STAINLESS STEEL…………………………………………………………………………………. 10
- HYDROCHLORIC ACID…………………………………………………………………………… 10
- CHAPTER TWO:LITERATURE REVIEW………………………………………………………………………… 11
- CORROSION INHIBITION OF METALS IN VARIOUS MEDIA……………………………….. 11
- CORROSION INHIBITION OF STAINLESS STEEL IN VARIOUS MEDIA………………… 14
- CHAPTER THREE: MATERIALS AND METHODS…………………………………………………………… 16
- MATERIALS………………………………………………………………………………………………………. 16
- METHODS………………………………………………………………………………………………………… 16
- EXTRACTION OF TAMARIND AND TROPICAL ALMOND……………………………………………. 16
- PREPARATION OF STAINLESS STEEL…………………………………………………………………………. 16
- PREPARATION OF CORROSION INHIBITION MEDIA…………………………………………………… 17
- GRAVIMETRIC ANALYSIS………………………………………………………………………………………… 17
- CHPATER FOUR: RESULTS AND DISCUSSION………………………………………………………………. 19
- GRAVIMETRIC ANALYSIS FOR TAMARIND………………………………………………………. 19
- GRAVIMETRIC ANALYSIS FOR TROPICAL ALMOND………………………………………… 22
- ADSORPTION MECHANISM FOR TROPICAL ALMOND………………………………………. 25
- EFFECTS OF TEMPERATURE…………………………………………………………………………….. 27
- CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS………………………………………… 28
- CONCLUSIONS………………………………………………………………………………………………….. 28
- RECOMMENDATIONS……………………………………………………………………………………….. 28
REFERENCES……………………………………………………………………………………………………………….. 29
LIST OF TABLES
Table 4.1: Result for the gravimetric analysis of Tamarindus indica…………………………………….. 19
Table 4.2: Modelled/Predicted values for Tamarindus indica………………………………………………. 20
Table 4.3: Result for gravimetric analysis of Terminalia catappa…………………………………………. 22
Table 4.4: Modelled/Predicted values for Terminalia catappa…………………………………………….. 23
Table 4.5: Adsorption mechanism for Terminalia catappa………………………………………………….. 26
Table 4.6: Effect of temperature on the Terminalia catappa extracts…………………………………… 27
Table 4.7: Effect of temperature on the Tamarindus indica extracts…………………………………….. 27
LIST OF FIGURES
Figure 4.1: Corrosion rate vs concentration graph for tamarind……………………………………………. 20
Figure 4.2:Inhibition efficiency vs Temperature graph for tamari………………………………………… 20
Figure 4.3: Weight loss vs concentration graph for tamarind………………………………………………. 21
Figure 4.4: Weight loss vs Time graph for tamarind at 30°C……………………………………………….. 21
Figure 4.5: Weight loss vs Time graph for tamarind at 50°C……………………………………………….. 21
Figure 4.6: Weight loss vs Time graph for tamarind at 40°C……………………………………………….. 21
Figure 4.7: Corrosion rate vs Concentration graph for tropical almond………………………………… 24
Figure 4.8: Inhibition efficiency vs Temperature graph for tropical almond………………………….. 24
Figure 4.9: Weight loss vs Concentration graph for tropical almond…………………………………….. 24
Figure 4.10: Weight loss vs Time graph for tropical almond at 30°C…………………………………… 24
Figure 4.11: Weight loss vs Time graph for tropical almond at 40°C……………………………………. 24
Figure 4.12: Weight loss vs Time graph for tropical almond at 50°C……………………………………. 24
Figure 4.13: Langmuir Isotherm graph for tropical almond………………………………………………… 26
Figure 4.14: Temkin Isotherm graph for tropical almond……………………………………………………. 26
CHAPTER ONE: INTRODUCTION
- PROBLEM STATEMENT
Metals are used in many industries and they come in contact with a lot of chemicals. The oil industry especially makes use of metals in different applications, which include, pipeline construction, oil tankers, oil well engineering, oil rigs construction, etc. Metal surfaces stand a risk of being attacked by acids used in cleaning them; this leads to corrosion. Corrosion has a lot of effects in different areas in our lives; these areas include economic, safety and environmental. Economically, a lot of cost are put into consideration and accounted for due to corrosion. Corrosion could wear out a machine and could render it useless when not discovered on time. The machine will then have to be replaced adding to the costs incurred. Costs are also incurred as regards to controlling corrosion, by either maintaining the machine or repairing it, or specially designing the machine to resist or withstand attacks by corrosive media1.In safety, corrosion poses a great threat to human life, aquatic life and the life of other animals. For example, the corrosion of iron hulls in ships and the subsequent effects poses a serious threat to the lives of the people aboard.
The corrosion of oil pipelines poses a big threat to the people living in that area, as the subsequent breakdown and explosion of the pipeline could destroy lives. Also, corrosion of drill pipes could cause a breakage and explosion, leading to loss of lives and injury. Breakdown of bridges due to corrosion has caused the loss of lives and property1. Furthermore, airline accidents due to corrosion have caused the loss of many lives and people have lost their jobs due to loss of confidence by customers. A popular example is that of the Aloha airlines Boeing 737 air accident in 1988 where the plane lost a major portion of the upper fuselage in full flight at 24000 ft. above the ground. Although only one loss was recorded, several injuries were also recorded2.
Corrosion has many effects on the environment with the fact that corrosion related failure of pipelines and oil tanks can cause serious problem for the environment as regards the pollution of lands, water and the air. Oil spills due to corrosion have caused loss of vegetation and aquatic lives. Many have lost their farmlands and means of livelihood due to corrosion related oil spill and other activities1.
In this research, a comparative study was carried out with tamarind and tropical almond leaves extracts on the corrosion inhibition of stainless steel in 1M hydrochloric acid with focus on maximizing the inhibition efficiency of the inhibitors.
