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

3,000.00

CHAPTER ONE: INTRODUCTION
1.1 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.
2

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.

1.2 MOTIVATION
Corrosion affects the integrity of materials, especially metals used in different industries. The oil
industry is one of the most important industries in Nigeria, with oil being its main source of
revenue. It is known that the industry makes use of metallic materials either as pipelines, gas
tanks, oil rigs, or in well engineering. Ships and boats used in transporting materials offshore are
also made using metals.
At the Shell Nigeria Exploration and Production Company (SNEPCo) dedicated base, it
discovered that due to non-availability of space inside their warehouse some of their materials
are being kept outside and get beaten by rain and sunshine. These materials get attacked by the
extreme conditions and often corroded. The company thus invests a lot of time and money into
keeping the materials in shape, by cleaning them and repainting them. Also, the company had to
off-hire vessels because corrosion and other minor damages had made them unfit for sail. If the
maximum efficiency is obtained in this research, the company could have an option of using
cheap, easily available, and long-lasting inhibitors to preserve their metal equipment.

3

1.3 AIM AND OBJECTIVES
The aim of this project was to use the predicted concentrations of Tamarindus indica and
Terminalia catappa leaves extracts to obtain maximum inhibition efficiencies of Tamarindus
indica and Terminalia catappa leaves extracts on corrosion of stainless steel in 1 M HCl. The
objectives of this project were:
1. To extract the Tamarindus indica and Terminalia catappa inhibitors from their leaves.
2. To study corrosion inhibition of stainless steel in 1M HCl using 0.9g/15mL, 1.1g/15mL,
1.3g/15mL, concentrations of the Terminalia catappa extracts at 30˚C, 40˚C, and 50˚C
temperatures.
3. To study corrosion inhibition of stainless steel in 1M HCl using 2.4g/15mL, 2.3g/15mL,
5.4g/15mL concentrations of Tamarindus indica extracts at the same temperatures as Terminalia
catappa.
4. To determine the inhibition efficiency of both leaves extracts on stainless steel in 1M HCl.
5. To determine the effects of temperature on the inhibition efficiency of the extracts and to
calculate the adsorption kinetics of the extracts.

1.4 SCOPE OF PROJECT
This research was focused on the following scopes of study:
CHAPTER 1
This chapter looks into the introduction of the topic, the aim and objectives of the research, the
problem to be solved in the research, the overview of the research, and motivation.
CHAPTER 2
This chapter examines different articles and researches on corrosion, its sources, and various
ways that have been applied in the past and potential inhibition strategies by others. Factors
4

which affect the selection of a particular type of technique and inhibitor, for instance in what
media, which inhibitor works best in, acidic, alkaline, saline or neutral. The inhibition
mechanism is also covered here.
CHAPTER 3
This chapter deals with the materials/reagents used in carrying out the research and the procedure
used in successfully carrying out the experiment. It also includes the different formulas and
methods used in analyzing the results.
CHAPTER 4
This chapter contains the results and discussion on the weight loss measurements for the metals.
These results include values from the calculations of the inhibition efficiency, corrosion rates,
surface coverage, adsorption kinetics, and temperature effects. The graphs that compare these
terms for the two extracts used are also shown.
CHAPTER 5
In this chapter, a summary of the whole research is discussed, the importance of the research is
also emphasized and recommendations for improving this area of research are given as well.