ABSTRACT
Dehydrated Allium cepa (Onion) biomass was used to adsorb Cu2+, Pb2+ and Zn2+ from the human blood plasma in vitro. The samples were found to be free of Cu2+, Pb2+ and Zn2+ after screening using AAS. Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) analysis were carried out on the biosorbent before and after biosorption. Scanning Electron Microscope (SEM) analysis revealed physical disintegration in the surface morphology of biosorbent after biosorption while Fourier Transform Infrared (FTIR) analysis revealed a general shift in peaks of C-H stretch of alkane and alkyl groups, N-H symmetric amides, N-H bend amides, S=O sulfonyl, C-O stretch alcohols, O-H alcohols, ethers, esters and carboxyl functional groups after biosorption which is evidence of biosorption of these metal ions on the Allium cepa biomass. The optimisation of operational factors including solution pH, biosorbent concentration, initial metal (Cu2+, Pb2+ and Zn2+) ion concentration were investigated at physiological temperature. The optimum pH, initial metal ions concentration and biosorbent concentration for Cu2+ sorption was pH 6, 50 mgL-1 and 0.60 g respectively. The values obtained were used for the kinetic study and the highest percentage sorption of Cu2+ was 99.316 % at 70 min. The optimum of pH, initial metal ions concentration and biosorbent concentration for Pb2+ sorption was pH 4, 50 mgL-1 and 0.40 g respectively. The values obtained were used for the kinetic study and the highest percentage sorption of Pb2+ was 99.8914 % at 90 min. The optimum of pH, initial metal ions concentration and biosorbent concentration for Zn2+ sorption was pH 6, 50 mgL-1 and 0.80 g respectively. The values obtained were used for the kinetic study and the highest percentage sorption of Zn2+ was 97.8076 % at 80 min. The percentage removal of Cu2+, Pb2+ and Zn2+ are in the order of Pb2+ (99.8914 %) > Cu2+ (99.316 %) > Zn2+ (97.8076 %). The experimental data obtained for Cu2+, Pb2+ and Zn2+ sorption were treated using Langmuir, Freundlich and Temkin isotherm. Temkin isotherm provided the best fit with correlation coefficient (R2) values of 0.508, 0.901 and 0.620 respectively. Simple kinetic models such as pseudo-first-order, pseudo-second-order and intra-particle diffusion model were employed to determine the biosorption mechanism. The kinetic study followed pseudo second order while the intra-particle diffusion model was observed not to be the only rate limiting step. This result suggests that chemical adsorption process was more dominant which involves the formation of chemical bonds between the metal ions (Cu2+, Pb2+ and Zn2+) and cell wall and cell membrane of Allium cepa respectively. This study demonstrated that Allium cepa biomass could be used as biosorbent for the detoxification of Cu2+, Pb2+ and Zn2+ from human blood plasma.
TABLE OF CONTENTS
Cover page…………………………………………………………………………. i Fly leaf……………………………………………………………………………… ii Title page…………………………………………………………………………… iii Declaration………………………………………………………………………….. iv Certification………………………………………………………………………… v Dedication………………………………………………………………………….. vi Acknowledgement…………………………………………………………………. vii Abstract……………………………………………………………………………. viii Table of content……………………………………………………………………. ix List of Tables………………………………………………………………………….. xvii List of Figure………………………………………………………………………….. xviii List of Plates ……………………………………………………………………….. xx List of Appendices…………………………………………………………………. xxi List of Abbreviations………………………………………………………. ……… xxiv CHAPTER ONE: 1.0 INTRODUCTION……………………………………………………….. 1 1.1 Background of Study……………………………………………………… 1 1.2 Statement of Problem………………………………………………………. 3 1.3 Justification of Study…………………………………………………………………………. 3 1.4 Research Aim……………………………………………………………… 4 1.5 Objectives of Study……………………………………………………………………………. 4
ix
CHAPTER TWO: 2.0 LITERATURE REVIEW……………………………………………………………….. 6 2.1 Heavy Metals……………………………………………………………………………………. 6 2.1.1 Sources of Heavy metals……………………………………………………………………. 6 2.2 Copper……………………………………………………………………………………………… 7 2.2.1 Health effect of Copper………………………………………………………………………. 8 2.3 Lead…………………………………………………………………………………………………. 9 2.3.1 Health effect of Lead…………………………………………………………………………. 10 2.4 Zinc…………………………………………………………………………………………………. 10 2.4.1 Health effect of Zinc………………………………………………………………………….. 12 2.5 Heavy metal accumulation in the human body………………………………………. 14 2.6 Description of Allium cepa (Onion)…………………………………………………….. 16 2.6.1 Chemical constituent of Allium cepa……………………………………………………. 17 2.6.2 Therapeutic potential of Allium cepa…………………………………………………… 19 2.7 Blood……………………………………………………………………………………………… 21 2.7.1 Human blood plasma…………………………………………………………………………. 22 2.7.1.1 Importance of human blood plasma…………………………………………………….. 23 2.8 Biosorption………………………………………………………………………………………. 23 2.8.1 Factors affecting biosorption………………………………………………………………. 24 2.8.2 Biosorption Mechanism……………………………………………………………………… 25 2.8.2.1 Ion exchange…………………………………………………………………………………….. 26 2.8.2.2 Complexation……………………………………………………………………………………. 26
2.8.2.3 Chelation…………………………………………………………………………………………. 27
x
2.8.2.4 Precipitation……………………………………………………………………………………… 27 2.8.2.5 Coordination (Complex formation)……………………………………………………… 27 2.8.3 Biosorption Isotherm…………………………………………………………………………. 28 2.8.3.1 Langmuir Isotherm……………………………………………………………………………. 29 2.8.3.2 Freundlich Isotherm…………………………………………………………………………… 30 2.8.3 Temkin Isotherm……………………………………………………………………………….. 31 2.8.3.4 Separation Factor………………………………………………………………………………. 32 2.8.4.1 Lagergren Pseudo first order kinetics…………………………………………………… 32 2.8.4.2 Lagergren Pseudo Second order kinetics………………………………………………. 33 2.8.4.3 Intra-particle diffusion model …………………………………………………………….. 33 2.9 Previous Research on Biosorption……………………………………………………….. 35 CHAPTER THREE: 3.0 MATERIALS AND METHODS………………………………………… 44 3.1 Apparatus and Equipments………………………………………………………………… 44 3.2 Reagents and Samples……………………………………………………………………….. 44 3.3 Sample Collection…………………………………………………………………………….. 44 3.3.1 Collection of Allium cepa…………………………………………………………………… 44 3.3.2 Collection of human blood…………………………………………………………………. 45 3.4 Sample Preparation……………………………………………………………………………. 45 3.4.1 Preparation of Allium cepa for biosorption………………………………………….. 45 3.4.2 Preparation of human blood plasma…………………………………………………….. 45 3.5 Preparation of Stock Solutions……………………………………………………………. 46 3.5.1 Preparation of Cu (II) ion solution (1000 mgL-1)………………………………….. 46
3.5.2 Preparation of Pb (II) ion solution (1000 mgL-1)………………………………….. 46
xi
3.5.3 Preparation of Zn (II) ion solution (1000 mgL-1)…………………………………… 46 3.5.4 Preparation of 0.1M HNO3………………………………………………………. ………. 47 3.5.5 Preparation of 0.1M NaOH……………………………………………………………….. 47 3.6 Characterization of Samples……………………………………………………………… 47 3.6.1 Screening of Cu2+ in the human blood plasma…………………………………….. 47 3.6.2 Screening of Cu2+ in the biosorbent……………………………………………………. 48 3.6.3 FTIR analysis of biosorbent………………………………………………………………. 48 3.6.4 Fourier Transform Infrared Spectroscopy (FTIR) analysis of Cu2+ treated biosorbent…………………………………………… 49 3.6.5 Scanning Electron Microscope (SEM) analysis of biosorbent…………………. 49 3.7 Spiking of Blood Plasma with Cu (II) Ion Solutions……………………………….. 50 3.8 Optimisation of biosorption parameters for Cu (II) ions adsorption…………. 50 3.8.1 Optimization of pH for Cu (II) ions adsorption……………………………………… 50 3.8.2 Digestion of Filtrate……………………………………………………………….. ………… 51 3.8.3 Optimisation of Cu (II) ions concentration…………………………………………….. 51 3.8.4 Optimisation of biosorbent dosage for Cu (II) ions adsorption………………….. 52 3.8.5 Study of the rate of biosorption of Cu (II) ions………………………………………… 52 3.9 Optimisation of biosorption parameters for Pb (II) ions adsorption……………. 53 3.9.1 Optimization of pH for Pb (II) ions adsorption……………………………………….. 53 3.9.2 Digestion of Filtrate………………………………………………………………… …………. 53 3.9.3 Optimization of Pb (II) ions concentration……………………………………………… 53 3.9.4 Optimization of biosorbent dosage for Pb (II) ions adsorption………………….. 54 3.9.5 Study of the rate of biosorption of Pb (II) ions……………………………………….. 54 3.10 Optimisation of biosorption parameters for Zn (II) ions adsorption…………. . 55 3.10.1 Optimization of pH for Zn (II) ions adsorption………………………………………. 55
xii
3.10.2 Digestion of Filtrate …………………………………………………………………………. 55 3.10.3 Optimization of Zn (II) ions Concentration………………………………… ……….. 56 3.10.4 Optimization of biosorbent dosage for Zn (II) ions adsorption………………… 56 3.10.5 Study of the rate of biosorption of Zn (II) ions………………………………………. 57 3.11 Data Evaluations……………………………………………………………………. ……….. 57 3.12 Data Analysis……………………………………………………………………….. ……….. 58 CHAPTER FOUR: 4.0 RESULTS…………………………………………………………………. 59 4.1 Fourier Transform Infrared (FTIR) of Biosorbent (Allium cepa)…………. 59 4.2 Scanning Electron Microscope (SEM) of Biosorbent (Allium cepa)……… 63 4.3 Optimum Parameters………………………………………………………. 67 4.3.1 Optimum parameters for biosorption of Cu (II) ion……………………….. 67 4.3.2 Rate of removal of Cu (II) Ion…………………………………………………………….. 70 4.3.3 Optimum parameters for biosorption Pb (II) ion…………………………… 71 4.3.4 Rate of removal of Pb (II) ion………………………………………………………………. 74 4.3.5 Optimum parameters for Biosorption of Zn (II) ion………………………… 75 4.3.6 Rate of removal of Zn (II) ion………………………………………………………………. 78 4.4 Equilibrium Isotherms………………………………………………………………………… 79 4.4.1 The Langmuir, Freundlich and Temkin Isotherms Modelling for Cu (II) ions uptake…………………………………………………………. 79 4.4.2 The Langmuir, Freundlich and Temkin Isotherms Modelling for Pb (II) ions uptake………………………………………………………….. 83 4.4.3 The Langmuir, Freundlich and Temkin Isotherms Modelling for Zn (II) ions uptake…………………………………………… 87 4.5 Biosorption Kinetics………………………………………………………… 91
xiii
4.5.1 Lagergren Pseudo first order, Pseudo second order and Intra-particle diffusion kinetic models for biosorption of Cu (II) ions…………………………… 91 4.13 Lagergren Pseudo first order, Pseudo second order and Intra-particle diffusion kinetic models for biosorption of Pb (II) ions……………………………. 95 4.14 Lagergren Pseudo first order, Pseudo second order and Intra-particle diffusion kinetic models for biosorption of Cu (II) ions…………………………… 99 CHAPTER FIVE: 5.0 DISCUSSIONS…………………………………………………………………………………. 103 5.1 Characterization of Samples…………………………………………………………………. 103 5.1.1 Atomic Adsorption Spectroscopy Analysis of Samples……………………………. 103 5.1.2 Fourier Transform Infrared (FTIR) analysis of dried Allium cepa………….. 103 5.1.3 Fourier Transform Infrared (FTIR) of Cu (II) ion treated Allium cepa……… 104 5.1.4 Fourier Transform Infrared (FTIR) of Pb (II) ion treated Allium cepa………. 104 5.1.5 Fourier Transform Infrared (FTIR) of Zn (II) ion treated Allium cepa……… 105 5.1.6 Scanning Electron Microscope (SEM)………………………………………. 105 5.2 Optimum Parameters for Biosorption of Cu (II) ion………………………… 106 5.2.1 Optimum pH for biosorption of Cu (II) ion………………………………….. 106 5.2.2 Optimum concentration for biosorption of Cu (II) ion………………………. 106 5.2.3 Optimum biosorbent dose for biosorption of Cu (II) ion……………………. 107 5.2.4 Rate of biosorption of Cu (II) ions…………………………………………… 108 5.2.5 Langmuir Isotherm for biosorption of Cu (II) ions……………………………………. 108 5.2.6 Freundlich isotherm for biosorption Cu (II) ions………………………………………. 108 5.2.7 Temkin Isotherm for biosorption of Cu (II) ions………………………………………. 109 5.2.8 Lagergren Pseudo first order model for biosorption of Cu (II) ions…………….. 109 5.2.9 Lagergren Pseudo Second order model for biosorption of Cu (II) ions……….. 109
5.2.10 Intra-particle diffusion model for Cu (II) ion biosorption………………………….. 110
xiv
5.3 Optimum Parameters for biosorption of Pb (II) ions…………………………………. 110 5.3.1 Optimum pH for biosorption of Pb (II) ions………………………………………………. 110 5.3.2 Optimum concentration for biosorption of Pb (II) ions……………………………….. 111 5.3.3 Optimum biosorbent dose for biosorption of Pb (II) ions…………………………….. 111 5.3.4 Rate of biosorption of Pb (II) ions……………………………………………………………. 112 5.3.5 Langmuir Isotherm for biosorption of Pb (II) ions……………………………………… 112 5.3.6 Freundlich isotherm for biosorption of Pb (II) ions…………………………………….. 113 5.3.7 Temkin Isotherm for biosorption of Pb (II) ions………………………………………… 113 5.3.8 Lagergren Pseudo first order model for biosorption of Pb (II) ions………………. 114 5.3.9 Lagergren Pseudo Second order model for biosorption of Pb (II) ions…………. 114 5.3.10 Intra-particle diffusion model for Pb (II) ion biosorption…………………………….. 114 5.4 Optimum Parameters for biosorption of Zn (II) ions…………………………………… 115 5.4.1 Optimum pH for biosorption of Zn (II) ions………………………………………………. 115 5.4.2 Optimum concentration for biosorption of Zn (II) ions………………………………. 115 5.4.3 Optimum biosorbent dose for biosorption of Zn (II) ions………………………….. 116 5.4.4 Rate of biosorption of Zn (II) ions…………………………………………………………… 117 5.4.5 Langmuir Isotherm for biosorption of Zn (II) ions…………………………………….. 117 5.4.6 Freundlich isotherm for biosorption Zn (II) ions……………………………………….. 118 5.4.7 Temkin Isotherm for biosorption of Zn (II) ions……………………………………….. 118 5.4.8 Lagergren Pseudo first order model for biosorption of Zn (II) ions……………… 118 5.4.9 Lagergren Pseudo Second order model for biosorption of Zn (II) ions…………. 119 5.4.10 Intra-particle diffusion model for Zn (II) ion biosorption…………………………… 119
xv
CHAPTER SIX: 6.0 SUMMARY, CONCLUSION AND RECOMMENDATION…………….. 120 6.1 Summary……………………………………………………………………… 120 6.2 Conclusion…………………………………………………………………… 121 6.3 Recommendations…………………………………………………………… 122 Reference…………………………………………………………………………… 123 Appendix……………………………………………………………………………. 1
CHAPTER ONE
INTRODUCTION 1.1 Background of Study People are exposed to a variety of potentially harmful agents in the air they breathe, the liquids they drink, the food they eat, the surfaces they touch and the products they use. An important aspect of public health protection is the prevention or reduction of exposures to environmental agents that contribute, either directly or indirectly, to increased rates of premature death, disease, discomfort or disability (WHO, 2000). Chemicals have become an indispensable part of human life, sustaining activities and development, preventing and controlling many diseases, and increasing agricultural productivity. Despite their benefits, chemicals may, especially when misused, cause adverse effects on human health and environmental integrity. The widespread application of chemicals throughout the world increases the potential of adverse effects. Heavy metals are among the chief constituents of these chemicals. Heavy metals are very harmful in reference to their non biodegradable nature, long biological half lives and their potential to accumulate in different body parts. Most of the heavy metals are extremely toxic because of their solubility in water. Even at low concentrations heavy metals can have damaging effects in human beings and animals as there is no good mechanism for their elimination from the body. The heavy metals are taken up faster than they are metabolized or excreted (WHO, 2000). Even those heavy metals which are considered to be essential can become toxic in case when present in excess. The heavy metals can impair important biochemical processes posing a threat to human health (Gupta and Rastogi, 2009).
These toxic metals tend to enter the human body through, inhalation and consumption of contaminated plant and animals as food. They accumulate in the human
2
system dependent and independent of metabolism (Veglio and Beolchini, 1997). These toxic metals ions are transported to various parts of the human body through the human blood plasma (The main medium for excretory product transportation). With the aid of some biological activities in the human body and the ingestion of some chemical constituents into the human system, these toxic metals can be excreted, utilizing various elimination activities including biosorption (Christopher, 2005; Jaishankar et al., 2014). Biosorption is an emerging technology that uses biological materials to remove metals from solution through adsorption. Biosorbent from biological materials contains various types of functional sites such as amino, hydroxyl and carboxyl where it can react to form passive uptake of metals from aqueous solution (Bakircioglua et al., 2010; Wang and Chen. 2009). Land plants, aquatic plants and herbs have all attracted considerable attention for the capacity to eliminate metals from the environment. Mechanisms responsible for biosorption, although understood to a limited extent, may be one or combination of ion exchange, complexation, coordination, adsorption, electrostatic interaction, chelation and microprecipitation (Veglio and Beolchini, 1997; Vijayaraghavan and Yun, 2008; Wang and Chen, 2006). Allium cepa (Onion) is a member of Allium family. Studies have shown that this plant contains some powerful chemical constituent such as quercetine, flavonoids, capeanes, organosulphur compounds and dietary fibres. It is believed that these chemical constituent contains functional groups which are capable of binding the metals. These molecules as organometallic complexes, are further partitioned inside vacuoles to facilitate appropriate control of the cytoplasmic concentration of heavy metal ions, thus preventing or neutralizing their potential toxic effect (Cobbett and Goldsbrough, 2002).
3
1.2 Statement of Research Due to the increasing amount of neuro-toxic chemicals and heavy metals in the environment, the resultant accumulation of heavy metals in the human body poses significant health risks (Adriano, 1986). Chronic exposure from occupational, environmental, dental amalgam, and contaminated food is a significant threat to public health. These metals bind with protein sites which are not made for them by displacing original metals from their natural binding sites causing malfunctioning of cells and ultimately toxicity leads to arygria, a blue-gray discoloration of the skin and other body tissues, chest pain, tightness of the chest, shortness of breath (Pattabhi et al 2008). These toxic metals are difficult to eliminate due to their persistent and cumulative nature. The development of new and more effective technologies becomes essential. This work was undertaken to study heavy metal detoxification of human plasma using Allium cepa as biosorbent. The result from this work will provide qualitative information on the effective use of Allium cepa as biosorbent for the detoxification of human plasma. 1.3 Justification of Study
The hazardous and adverse effects caused by heavy metals present in the environment emerging from different industries are of significant environmental concern. Heavy metals are non-biodegradable and bioaccumulates in living organisms thereby causing various damages, diseases and disorder. Hence, attention is currently on the use of cost effective biosorbent which studies have shown to exhibit high adsorption capacity of unwanted pollutants (Ahalya et al., 2003). Several biological and chemical methods such as filtration, coagulation, oxidation, solvent extraction, and reverse osmosis have been used for heavy metal treatment in the environment. However, the increase in the variety and
4
amount of hazardous chemicals present in the environment, makes these conventional methods inefficient. Consequently, the development of new and more effective technologies and biosorbents has becomes essential; therefore it is important to investigate the heavy metal adsorption capacity or efficiency of some herbs and vegetables from the human system. Allium cepa was investigated because of its high medicinal values and its commercial availability in the market. There has not been any known work in using them to detoxify the human plasma of the heavy metals under study. 1.4 Aim of the Research The aim of this work is to study the metals (Cu2+, Pb2+, and Zn2+) uptake capacity of Allium cepa from the human plasma. 1.5 Objectives of the Research The aim of the study was achieved through the following objective
• Collection of healthy Human blood sample.
• Collection of sample of Allium cepa (Onion bulb).
• Centrifugation of the blood sample and collection of the human plasma.
• Screening of the human plasma to identify the concentration of metal ions (Cu2+, Pb2+ and Zn2+) present in it.
• Preparation of sample of dehydrated Allium cepa which was then used as biosorbent prior to analysis
• Screening of the prepared biosorbent to identify the concentration of metal ions (Cu2+, Pb2+ and Zn2+) present using AAS.
• Carryout FTIR analysis of the prepared native and metal ions treated biosorbent to identify the binding sites.
5
• Optimisation of the biosorption parameters at varying pH, varying concentrations of heavy metals (Cu2+, Pb2+ and Zn2+), and biosorbent concentration.
• Fit the experimental data obtained into Langmuir and Freundlich and Tempkin isotherms.
• Study the kinetics of Cu2+, Pb2+, and Zn2+ ion sorption using pseudo first order kinetic model, pseudo second order kinetic model and Intra-particle diffusion kinetic model.
6
IF YOU CAN'T FIND YOUR TOPIC, CLICK HERE TO HIRE A WRITER»
