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SORPTION OF COPPER (II) IONS FROM AQUEOUS SOLUTIONS BY REGENERATED SPENT BLEACHING EARTH
Copper pollution of water systems has increased greatly in the recent years in many parts of the world because of increased industrial demand for copper, its heavy use in agrochemicals and inefficiency of conventional water filtration techniques. The present study was designed to investigate the efficacy of Spent Bleaching Earth (SBE) as a low cost adsorbent for the removal of copper from aqueous solutions. The SBE, a clay waste generated by edible oil refineries, was washed in excess methyl-ethyl ketone and subjected to heat and/or acid treatments at various conditions. The resultant regenerated spent bleaching earth (RSBE) was then used in a series of experiments to assess its ability to sorb Cu (II) ions from aqueous solutions.
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| language |  | english |
| wordcount |  | 25322 (cca 72 pages) |
| contextual quality |  | N/A |
| language level |  | N/A |
| price |  | free |
| sources |  | 106 |
Table of contents
LIST OF TABLES viii
LIST OF FIGURES ix
ABBREVIATIONS AND ACRONYMS xi
ABSTRACT xii
CHAPTER ONE: INTRODUCTION 1
1.1 BACKGROUND TO THE PROBLEM 1
1.2 PROBLEM STATEMENT AND JUSTIFICATION. 2
1.3 OBJECTIVES 4
1.3.1 GENERAL OBJECTIVE 4
1.3.2 SPECIFIC OBJECTIVES 4
CHAPTER TWO: LITERATURE REVIEW 6
2.1 COPPER METAL 6
2.2 CLAYS 7
2.2.1 CLAY MINERALS 8
2.2.2 BLEACHING CLAYS/EARTHS 10
2.2.3 BLEACHING OF EDIBLE OILS 11
2.2.4 SPENT BLEACHING EARTH (SBE) 12
2.3 SEWAGE TREATMENT METHODS 13
2.4 DETERMINATION OF SOIL EXTRACTABLE CARBON 13
2.5 SORPTION STUDIES 15
2.5.1 DEFINITION 15
2.5.2 SORPTION THEORIES 15
2.5.2.1 Langmuir theory of monolayer chemisorptions 15
.2.5.2.2 Freundlich Adsorption Theory 17
2.5.3 EXPERIMENTAL METHODS 19
2.5.4 KINETIC ANALYSIS 20
2.5.5 THERMODYNAMIC PARAMETERS OF ADSORPTION 22
2.5.6 METAL SORPTION ON CLAYS AND THEIR FRACTIONS 23
2.5.6.1 General Sorption Behavior of Metals on Clays and Clay Fractions 23
2.5.6.2 Copper Sorption Properties at the Clays and Clay Fraction 27
2.5.7 METAL DESORPTION STUDIES FROM CLAYS AND THEIR FRACTIONS 28
2.6 ANALYTICAL TECHNIQUES 28
2.6.1 POLAROGRAPHY `28
2.6.1.1 Principles of Polarography 28
2.6.1.2 Polarographic Modes 32
2.6.2.2 Quantitative Methods in Polarography 34
2.6.2 X-RAY FLUORESCENCE ANALYSIS (XRFA) 35
2.6.3 FLAME PHOTOMETRY 37
2.6.4 ATOMIC ABSORPTION SPECTROSCOPY (AAS) 39
2.6.5 USE OF ION-SELECTIVE MEMBRANE ELECTRODES 40
CHAPTER THREE: METHODOLOGY 43
3.1 SBE PRE-TREATMENT 43
3.2 REAGENTS. 43
3.3 PREPARATION OF SBE FOR COPPER ADSORPTION 43
3.3.1 HEAT REACTIVATION 43
3.3.2 ACID-REACTIVATION OF SBE 44
3.3.3 COMPARISON OF REACTIVATION EFFICIENCIES OF HEAT, DILUTE ACID AND SOLVENT TREATMENTS 44
3.4 EXPERIMENTAL PROCEDURES 45
3.4.1 SBE CHEMICAL AND SURFACE CHARACTERIZATION 45
3.4.1.1 Elemental Analysis of the Materials by XRF 45
3.4.1.2 Determination of Potentially Available Copper 45
3.4.1.3 Determination Oxidizable Carbon Content 46
3.4.1.4 Evaluation of Point of Zero Net Charge, (PZNC) 46
3.4.1.5 SBE pH Determination 47
3.4.1.6 Evaluation of Cation Exchange Capacity 47
3.4.2 ADSORPTION EXPERIMENTS 48
3.4.2.1 Effects of Time of Contact 49
3.4.2.2 Effects of Adsorbent Dosage 49
3.4.2.3 Effects of Initial Equilibrium pH 50
3.4.2.4 Effects of Initial Adsorbate Copper Concentrations 50
3.4.2.5 Effects of ionic Strength 50
3.4.2.6 Effects of Calcium ions 51
3.4.3 DESORPTION STUDIES 51
3.4.3.1 Effects of Initial Concentration 51
3.4.3.2 Effects of Time of Contact on SBE Cu (II) Desorption 52
CHAPTER FOUR: RESULTS AND DISCUSSION 53
4.1 CHEMICAL AND SURFACE PROPERTIES OF RSBE 53
4.1.1 CHEMICAL COMPOSITIONS 53
4.1.2 POTENTIALLY AVAILABLE COPPER IN THE MATERIAL 55
4.1.3 SURFACE PROPERTIES 55
4.2 REGENERATION PROPERTIES OF SBE FOR SORPTION OF COPPER 57
4.2.1 HEAT TREATMENT OF SBE 57
4.2.2 EFFECTS OF ACID TREATMENT OF SBE 61
4.2.3 REACTIVATION EFFICIENCIES FOR VARIOUS SBE TREATMENT CONDITIONS 66
4.3 EFFECTS OF CHANGE IN VARIOUS ADSORPTION PARAMETERS ON SBE SORPTION OF COPPER 68
4.3.1 TIME PROFILE OF COPPER SORPTION BY SBE 68
4.3.2 EFFECTS OF INITIAL CONCENTRATION OF COPPER 70
4.3.3 EFFECTS OF IONIC STRENGTH OF THE BACKGROUND SOLUTION 74
4.3.4 EFFECTS OF CALCIUM IONS ON SBE SORPTION OF COPPER 76
4.3.5 EFFECTS OF CHANGE IN SORBENT DOSAGE 78
4.3.6 EFFECTS OF PH 81
4.4 DATA FIT TO EQUILIBRIUM ADSORPTION ISOTHERMS 87
4.4.1 LANGMUIR ISOTHERM 87
4.4.2 FREUNDLICH EQUILIBRIUM ISOTHERM 90
4.4.3 LINEAR PARTITION EQUILIBRIUM ISOTHERM 92
4.5 ADSORPTION THERMODYNAMICS 95
4.6 ADSORPTION KINETICS 96
4.7 COPPER DESORPTION FROM RSBE 101
4.7.1 EFFECTS OF INITIAL COPPER CONCENTRATION ON ITS DESORPTION FROM SBE 102
4.7.2 EFFECTS OF TIME OF EXPOSURE TO THE DESORBING AGENTS ON COPPER DESORPTION 106
CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS 111
5.1 CONCLUSIONS 111
5.2 RECOMMENDATIONS 112
REFERENCES 114
APPENDICES 123
APPENDIX I: LANGMUIR ISOTHERMS 123
APPENDIX II: FREUNDLICH ISOTHERMS 127
APPENDIX III: LINEAR PARTITION ISOTHERMS 131
APPENDIX IV: ADSORPTION KINETICS MODELS 135
Preview of the essay: SORPTION OF COPPER (II) IONS FROM AQUEOUS SOLUTIONS BY REGENERATED SPENT BLEACHING EARTH
The aesthetic and practical qualities of copper dates back to man’s emergence from the late Stone Age (Lanier, 1965); over 10,000 years ago. Its first metallurgical processing is accredited to Egyptians and the Romans at about 3800 B.C. although it was not until the 19th century that large scale smelting of the metal was reported. World copper consumption since then took extraordinary dimensions towards the end of 20th century reaching 8.5 billion tones per annum in 1976 and more than 22 billions by 1979 (Mikesell, 1976). Copper metal has therefore been considered the most versatile industrial element after Iron (Nriagu, 1979). The metal has found extensive usage in therapy, jewelry, formulation of agro-chemicals owed to its toxicological qualities to the lower biota (Cohen, 1979) and in food supplementation in swine and poultry production (Batey et al., 1972). It is an essential micronutrient associated with prosthetic enzymes. In crustaceans for instance, the metal is the haemocyanin equivalent of iron in the blood hemoglobin. Every adult Human being ingests 2-5 mg in essential copper daily ...
... showing that the type of acid counter ion affect copper desorption from RSBE of the acid. This is consistent with the work of Homann and Zasoski (1987) and McNaughton and James (1974) both of whom demonstrated that the presence of some ligand ions in the sorption equilibrium reduces metal ions adsorption on to clay adsorbents through metal-ligand complexation in the aqueous phase. The higher influence of the sulphate ions over the chloride ion on copper desorption reported in this work is attributable to formation of stronger soluble copper-sulphato complexes than the Cu-chloro complexes because of former ion’s higher charge density. This is also consistent with the hard acid-base theory. As can be seen from Table 4.19 the oxygen centers in the sulphate ion are considered hard relative to the chloride ions. They are therefore expected to interact more strongly with Cu2+ ions than the latter.
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