SYNERGISTIC EFFECT OF DATURA STRAMONIUM LEAVES EXTRACT - Z2n+ ON THE CORROSION INHIBITION OF MILD WELLWATER
ABSTRACT
The synergistic effect of Datura stramonium leaves extract and Zn2+ in the corrosion inhibition of mild steel in aqueous medium (100ml well water) was investigated in this project. The corrosion inhibition studies were carried out using weight loss method (gravimetric technique). The inhibition efficiency was found to increase with increase in extract concentration. The inhibition efficiency of the extract-Zn2+ was found to be 90% at DSLE extract and Zn2+ concentrations of 8ml and 5ppm respectively. The synergism factor at the same concentration was found to be 1.25 which indicates a synergistic effect exists between the inhibitors. The corrosion rate was also found to reduce with increase in extract concentration.
 
TABLE OF CONTENTS
CHAPTER ONE    1
1.1    BACKGROUND OF STUDY    2
1.2    STATEMENT OF THE PROBLEM    3
1.3    JUSTIFICATION    3
1.4    AIMS AND OBJECTIVES    4
1.4.1    AIM    4
1.4.2    OBJECTIVES    5
1.5    SCOPE OF THE RESEARCH    5
1.6    CONTRIBUTION TO KNOWLEDGE    5
CHAPTER TWO    6
2.0    LITERATURE REVIEW    6
2.1    CORROSION    6
2.1.1    EFFECTS OF CORROSION ON METALS    6
 
2.1.2    FORMS OF CORROSION    8    
2.2    CORROSION INHIBITION            8    
2.3    CLASSIFICATION OF INHIBITORS        9        
2.3.1    INORGANIC INHIBITORS                10
2.3.2    ORGANIC INHIBITORS                11

2.3.3    MIXED INHIBITORS AND SYNERGISTIC EFFECT ON CORROSION INHIBITION11
2.3.4    EXAMPLES OF COMBINED EXTRACTS    13
2.4    APPLICATION AND ENGINEERING IMPORTANCE OF CORROSION

    INHIBITION        12    
2.5.1    STEEL            14
2.5.2    TYPES OF STEEL    15        
2.6.1    CARBON STEEL    15        
2.7.1    ALLOY STEELS            16

2.7.3 STAINLESS STEELS    17
CHAPTER THREE    18
3.0    MATERIALS AND METHODS    18
3.1    MATERIALS    18
3.2    METHODS    18
3.2.1    MILD STEEL SPECIMEN PREPARATION    18
3.2.2    PREPARATION OF DATURA STRAMONIUM LEAF EXTRACT    19
3.2.3    PREPARATION OF Zn2+ SOLUTION IN 5PPM CONCENTRATION    20
3.2.4    PREPARATION OF AQUEOUS MEDIUM FOR CORROSION INHIBITION TEST 20
3.3    WEIGHT LOSS EXPERIMENT AT ROOM TEMPERATURE    20
 
3.3.1    SAMPLES        21
3.4    DETERMINATION OF CORROSION RATE (C.R)    22    
3.5    DETERMINATION OF PERCENTAGE INHIBITION EFFICIENCY (%I.E)        22
3.6    DETERMINATION OF SURFACE COVERAGE (?)    23    
3.7    DETERMINATION OF SYNERGISM FACTOR (S?)        23

CHAPTER FOUR    24
4.0    RESULTS AND DISCUSSION    24
4.1    RESULTS    24
4.2    DISCUSSION    27
4.2.1    WEIGHT LOSS METHOD    27
CHAPTER FIVE    30
5.0    CONCLUSION RECOMMENDATION    30
5.1    CONCLUSION    30
5.2    RECOMMENDATION    30
REFERENCES    31
APPENDIX    34
 
LIST OF TABLES

TABLE 4.1: SPECTROMETRIC COMPOSITION OF THE SPECIMEN 24

TABLE 4.2: CORROSION RATE AND INHIBITION EFFICIENCY OF MILD STEEL IMMERSED IN 5PPM Zn2+ IN PRESENCE OF DSLE 25
TABLE 4.3: SURFACE COVERAGE AND SYNERGISTIC FACTOR OF MILD STEEL IMMERSED IN 5PPM Zn2+ IN PRESENCE OF DSLE 25
 
LIST OF FIGURES
FIGURE 4.1: WEIGHT LOSS AGAINST CONCENTRATION OF DSLE    26
FIGURE 4.2 WEIGHT LOSS AGAINST CONCENTRATION OF DSLE + 5PPM OF ZN2+    26
 
CHAPTER ONE

1.0    INTRODUCTION

Corrosion is a phenomenon resulting in materials deterioration through chemical or electrochemical interaction with the environment. This process may compromise the mechanical and physical properties of equipments with serious economic and environmental impact in all infrastructure sectors, such as roads, oil and gas pipelines, construction and water and sewage systems, causing severe damage and threats to public safety and health (Lhaira et al, 2017). Corrosion is an expensive problem in the industrial world, according to American Galvanizer�s Association, Steel corrosion is a costly problem in fact the annual direct cost of metallic corrosion worldwide is $2.2 Trillion USD. North America is a large contributor to these annual costs, as the annual cost of corrosion in the US is $423 Billion the equivalent of 3.1% of the Gross Domestic Product (GDP). Though steel corrosion, whether in atmospheric, soil, water, or other exposures, is a natural phenomenon, estimates show 25-30% could be stymied if proper corrosion protection methods were employed (AGA, 2017).
Several methods have been employed in an attempt to control corrosion

 
some which are
 
the use of
 
inorganic compounds such as chromate, phosphates,
 

molybdates, etc and also a variety of organic compounds containing hetero atoms
 
such as nitrogen, sulphur and oxygen are being investigated as corrosion inhibitors. (Kavitha et al, 2014). Due to the toxic effect of inorganic corrosion inhibitors the search for green corrosion inhibitors have become utterly necessary as they are biodegradable, renewable and free from toxic compounds as well as heavy metals, a number of plant sources such as Polyalthia Longifolia, Oxystelma Esculentum, Eclipta alba, Red Onion etc has been reported as effective corrosion inhibitors.
This research focuses on the corrosion inhibition effect of Datura Stramonium leave extract � Z2n+ on mild steel in aqueous medium using weight loss and FTIR
 
spectra analysis.
 
The comparison
 
were made on the separate effect of both the
 

Datura Stramonium leave extract and the Zn2+extract on the corrosion inhibition of mild steel in the presence of well water and the combined effect of the extracts as corrosion inhibitors.
1.2    BACKGROUND OF STUDY

Corrosion is a natural phenomenon, which can be considered either chemical or electrochemical in nature, degrades the metallic properties of metal and it alloys thereby make them unfit for specific role, (Abiola et al, 2007). Corrosion of metals and it alloys particularly in aqueous medium is an important industrial problem as many industrial structures constructed with mild steel are done in areas where it
 
comes in regular contact with its
 
aqueous
 
environment, and this often results in
 
serious cases of corrosion. It is estimated that with proper corrosion prevention

 
technologies, about 25 to 30% of
 
the
 
losses due to corrosion could be avoided
 

(Gerhardus et al., 2002). This research focuses on the corrosion control of Mild steel using datura stramonium leaves extract � Z2n+, as mild steel an important metal alloy that has found wide range of mechanical and industrial application world-wide. It is one of the best preferred construction materials for industries due to its availability and mechanical properties, however, it is highly vulnerable to corrosion and pose high economic burden to replace.
1.2    STATEMENT OF THE PROBLEM

Corrosion remains a vast industrial problem and even though several methods of corrosion inhibition have been employed, some remain very harmful to the environment in which it is used. For instance, inorganic compounds are toxic and harmful to the environment and even expensive at the same time. There is therefore the need for safer, cheaper and more environmentally friendly means of corrosion inhibition.
1.3    JUSTIFICATION

The need to curb the failure of materials due to increased rate of corrosion cannot be overemphasized. Corrosion has so far contributed negatively towards technological, economical and even medical aspects of every nation. The problem
 
of corrosion has not been properly addressed through the use of conventional corrosion inhibitors such as synthesized organic and inorganic compounds due to their toxicity to the environment. Green plants therefore provide a better way to solve the problem of corrosion in both a cost-effective and environmentally- friendly manner. Green plant extracts containing phytochemicals such as tannins, saponins, terpanols, alkaloids among others have high inhibition efficiency against corrosion, biodegradable, and contains no heavy metals or toxic compounds. Apart from being environmentally friendly, they are also readily available, renewable and acceptable sources of corrosion inhibitors. Several corrosion inhibition studies have been carried out using different plant extracts as the inhibitors and has been reported as good corrosion inhibitors. However, experimental studies of the synergistic effect of Datura Stramonium leaves extract and zinc dust in well water have not been reported in literature.
1.4    AIM AND OBJECTIVES

1.4.1    AIM

The aim of this work is to evaluate the synergistic effect(s) of Datura stramonium leaves extract (DSLE) � Z2n+ on the corrosion inhibition of mild steel in aqueous medium (well water).
 
1.4.2    OBJECTIVES

The specific objectives of this study are to:

1.    determine the chemical composition of the metallic sample;
2.    assess the phytochemical constituents of the DSLE extract;
3.    assess the effects of varying quantities of the extract (DSLE) measured in milliliters (2ml, 4ml, 6ml, 8ml) in the absence and presence of Zn2+ on mild steel; and
4.    determine the mechanism of corrosion inhibition that is prevalent.

1.5    SCOPE OF THE STUDY

This study covers the evaluation of the synergistic effect of Datura stramonium leaves extract-Zn2+ in the corrosion inhibition of mild steel in well water.
Varying effects of different concentrations of the extract and 5ppm of Zn2+ on the corrosion inhibition of the mild steel specimen will be determined in order to ascertain the synergistic effect that exists between the leaf extract and Zn2+
1.6    CONTRIBUTION TO KNOWLEDGE

The study is expected to advance the frontiers of knowledge on the synergistic effect of green plants (datura stranomium leaves extract) and Zn dust for the corrosion inhibition of mild steel in well water.