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MODIFICATION, CHARACTERIZATION AND
UTILIZATION OF BANANA TRUNK FIBERS – Musa
acuminate x balbisiana Colla (ABB Group)
by
KATHIRESAN A/L V.SATHASIVAM
Thesis submitted in fulfillment of the requirements
for the degree of
Doctor of Philosophy
December 2010
ii
ACKNOWLEDGMENTS
I would like to express my deep and sincere gratitude to my supervisor; Associate
Professor Dr. Mas Rosemal Hakim Bin Mas Haris. His wide knowledge, his logical
and sometimes out of box way of thinking have been of great value for me. His
understanding, encouragements, constructive comments and personal guidance have
provided a good basis for the current thesis.
I wish to express my warm and sincere thanks to my field supervisor; Professor
S.Mohan. His kind support and guidance have been of great value in this study.
During this work I have collaborated with a few colleagues for whom I have great
regard, and I wish to extend my warmest thanks to them; Ms. Chong Wan Reng and
Ms. Guna Sunderi.
I owe my loving thanks to my wife, Kavitha Chrisnasamy and my sons Gaura
Kishore and Ram Keshava. Without their encouragement and understanding it
would have been impossible for me to finish this work. My special gratitude is due
to my parents, Mr& Mrs. V. Sathasivam for their loving and constant moral support.
My appreciation also goes to my ‗guru‘ HH Jayapataka Swami who has always been
a pillar in my life.
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Table of Content
Page
ACKNOWLEDGMENTS ......................................................................................................... ii
Table of Content ...................................................................................................................... iii
List of Figures…………………………………………………………………………………x
List of Tables………………………………………………………………………………..xiv
List of abbreviations and symbols .......................................................................................... xvi
Starting Materials and Products ................................................................................ xvi
Symbols. .................................................................................................................. xvii
Abstrak ..................................................................................................................................... xx
Abstract ................................................................................................................................... xxi
CHAPTER 1 .............................................................................................................................. 1
INTRODUCTION ..................................................................................................................... 1
1.1 History of Fibers .................................................................................................................. 1
1.2 Types of Natural fiber .......................................................................................................... 1
1.3 Properties of Natural and Synthetic Fibers .......................................................................... 2
1.3.1 Natural Fibers ..................................................................................................... 2
1.3.1.1 Physical Properties .............................................................................. 2
1.3.1.2 Chemical Properties ............................................................................. 3
1.3.2 Properties of Synthetic Fibers ............................................................................ 3
1.4 Lignocellulosic Fiber ........................................................................................................... 4
1.4.1 Advantage and Limitation of Lignocellulosic Fibers ......................................... 4
1.5 Cellulose .............................................................................................................................. 5
1.6 Lignin ................................................................................................................................... 6
1.7 Hemicellulose ...................................................................................................................... 7
1.8 Chemical Properties of Natural Fibers ................................................................................ 8
1.9 Moisture Absorption Characteristics ................................................................................... 9
iv
1.10 Chemical Treatment of Natural Fibers ............................................................................ 11
1.11 Surface Chemical Modifications of Natural Fibers ....................................................... 12
1.11.1 Mercerization .............................................................................................. 12
1.11.2 Acetylation ..................................................................................................... 13
1.11.3 Peroxide Treatment ........................................................................................ 14
1.11.4 Stearic Acid Treatment .................................................................................. 14
1.11.5 Acid Treatment ............................................................................................... 15
1.12 Research of Banana Trunk Fibers .................................................................................... 15
1.13 Pollution ........................................................................................................................... 17
1.14 Waste Water Treatment ................................................................................................... 18
1.14.1 Chemical Precipitation ................................................................................... 18
1.14.2 Electro-Deposition, Ion Exchange and Reverse Osmosis .............................. 18
1.14.3 Adsorption ...................................................................................................... 19
1.14.3.1 Adsorption of Dyes Using Natural Fibers ....................................... 19
1.14.3.2 Adsorption of Heavy Metals Using Natural Fibers ......................... 20
1.14.3.3 Adsorption of Oil Using Natural Fibers .......................................... 20
1.15 Composite ........................................................................................................................ 21
1.15.1 Biocomposite .................................................................................................. 21
1.15.2 Green Composite ............................................................................................ 22
1.15.2.1 Preparation of Green Composites .................................................... 23
1.16 Industrial Polymers .......................................................................................................... 25
1.16.1 Poly Vinyl Alcohol ......................................................................................... 25
1.17 Statement of Problem ...................................................................................................... 27
1.18 Purpose of Study .............................................................................................................. 28
1.19 Objective of Study ........................................................................................................... 29
1.20 Significance of Study ....................................................................................................... 29
1.21 Scope of Study ................................................................................................................. 29
v
CHAPTER 2: MATERIALS AND METHODS ................................................................. 31
2.1 Banana Trunk Fibers (BTF) ............................................................................................... 31
2.2. BTF Modification ............................................................................................................. 31
2.2.1. Mercerizations (BTF-1) ................................................................................... 31
2.2.2 Acetylation (BTF-2) ....................................................................................... 32
2.2.3 Peroxide Treatments (BTF-3) ........................................................................... 32
2.2.4 Stearic Acid Treatment (BTF-4) ...................................................................... 32
2.2.5 Sulphonation (BTF-5) ...................................................................................... 32
2.3 FTIR Analysis .................................................................................................................... 33
2.4 Fibers Morphology ............................................................................................................ 33
2.5 Thermogravimetry Analyses ............................................................................................. 33
2.6 Theoretical Approach for Thermal Analysis ..................................................................... 34
2.7 Methyl Red Adsorption Study ........................................................................................... 37
2.7.1 Sorbate .............................................................................................................. 37
2.7.2 Equilibrium Studies .......................................................................................... 37
2.8 Heavy Metal Adsorption Study ......................................................................................... 40
2.8.1Chemicals .......................................................................................................... 40
2.8.2 Equilibrium Studies .......................................................................................... 40
2.9 Engine Oil Adsorption Studies .......................................................................................... 41
2.9.1 Materials ........................................................................................................... 41
2.9.2 Equipments ....................................................................................................... 42
2.9.3 Preparation of Weathered Oil Contaminated Seawater (WOCS) ..................... 42
2.9.4 Preparation of Fatty Acid Grafted BTF ............................................................ 43
2.9.5 Equilibrium Studies .......................................................................................... 43
2.9.6 Study Effect of Light Oil .................................................................................. 44
2.9.7 Removal of Dissolved Organic Compounds (DOC) from WOCS ................... 44
2.9.8 Study Reusability of Sorbents .......................................................................... 44
vi
2.10 Treatment of Banana Trunk Fibers with Stearic Acid and Calcium Carbonate for the
Production of Green Composite .............................................................................................. 45
2.10.1 Preparation of Mechanically Damaged Banana Trunk Fibers ....................... 45
2.10.2 Treatment of MDBTF with Stearic Acid ........................................................ 45
2.10.3 Treatment of MDBTF with Calcium Carbonate Coated with 5% (wt/wt)
Stearic Acid ........................................................................................................... 45
2.10.4 Water Sorption Study ..................................................................................... 46
2.10.5 Moisture Sorption Study ................................................................................. 46
2.10.6 Morphological Analysis.................................................................................. 47
2.10.7 Roughness Study ............................................................................................ 47
2.10.8 Oil Uptake Study ............................................................................................ 47
2.11 Esterified Banana Trunk Fibers/Poly (Vinyl Alcohol) Blend Film ................................. 48
2.11.1 Esterification of Banana Dust ......................................................................... 48
2.11.2 Vibrational Studies of Several Industrial Polymers ....................................... 48
2.11.3 Preparation of Composite Film ...................................................................... 51
2.11.4 FTIR Spectroscopy ....................................................................................... 52
2.11.5 Thermogravimetric Analyzer (TGA) ............................................................. 53
2.11.6 Differential Scanning Calorimeter (DSC) ...................................................... 53
2.11.7 Mechanical Properties ................................................................................... 53
2.11.8 Moisture Sorption Study ................................................................................. 54
2.11.9 Swelling Behavior in Distilled Water ............................................................. 54
2.11.10 Morphological Analysis................................................................................ 55
CHAPTER 3: RESULTS AND DISCUSSION ................................................................... 56
3.1 FTIR Study ........................................................................................................................ 56
3.1.1 Unmodified BTF .............................................................................................. 56
3.1.2 Modified BTF ................................................................................................... 60
vii
3.2 Morphology Studies........................................................................................................... 63
3.2.1 Unmodified BTF .............................................................................................. 63
3.2.2 Modified BTF ................................................................................................... 65
3.3 Thermal Studies ................................................................................................................. 67
3.3.1 Unmodified BTF .............................................................................................. 67
3.3.2 Modified BTF ................................................................................................... 68
3.3.3 Determination of Apparent Energy .................................................................. 71
3.4 Methyl Red Adsorption Studies of Unmodified BTF ........................................................ 74
3.4.1 Effect of pH ...................................................................................................... 74
3.4.2 Effect of Contact Time ..................................................................................... 75
3.4.3 Optimization of Amount of Adsorbent ............................................................. 76
3.4.4 Concentration Dependent Study ....................................................................... 77
3.4.5 Agitation Study ................................................................................................. 78
3.5 Methyl Red Adsorption Studies of Modified BTF ............................................................ 80
3.5.1 Effect of pH on Dye Adsorption ..................................................................... 80
3.5.2 Effect of Initial Dye Concentration .................................................................. 81
3.5.3 Effect of Sorbent Dose ..................................................................................... 82
3.6 Adsorption Isotherm .......................................................................................................... 83
3.6.1 Langmuir Isotherm ........................................................................................... 83
3.6.2 Freundlich Isotherm Model .............................................................................. 86
3.7 Kinetics Models ................................................................................................................. 90
3.8 Removal of Cd(II), Cu(II), Fe(II) and Zn(II) from Aqueous Solutions ............................. 93
3.8.1 Effect of pH on Metal Ion Sorption .................................................................. 93
3.8.2 Effect of Contact Time and Initial Metal Concentration on Metal Adsorption 94
3.8.3 Optimization of Amount of Adsorbent ............................................................. 96
3.8.4 Concentration Dependent Study ....................................................................... 97
3.8.5 Effect of Change in [M2+]/Biomass ................................................................ 98
3.8.6 Adsorption Isotherms ....................................................................................... 99
viii
3.8.7 Adsorption Kinetics ........................................................................................ 101
3.8.8 Adsorption Capacity of the Modified Biomass .............................................. 104
3.9 Removal of Engine Oil from Aqueous Solutions ............................................................ 106
3.9.1 FTIR Study ..................................................................................................... 106
3.9.2 Effect of Oil to Water Ratio on the Sorption Capacity of the Unmodified and
Modified BTF ...................................................................................................... 109
3.9.3 Effect of Light Oil Fraction on the Engine Oil ............................................... 109
3.9.4 Weathering Process of Oil-Contaminated Seawater ...................................... 110
3.9.5 Effect of Concentration of DOC in WOCS .................................................... 111
3.9.6 Reusability of Sorbents ................................................................................... 112
3.9.7 Isotherm Study ................................................................................................ 113
3.9.8 Kinetics Study ................................................................................................ 122
3.9.9 Economic Viability ......................................................................................... 126
3.10 Treatment of Banana Trunk Fibers with Stearic Acid and Calcium Carbonate for the
Production of Green Composite ............................................................................................ 126
3.10.1 Water Sorption Study ................................................................................... 126
3.10.2 Moisture Sorption Study ............................................................................... 128
3.10.3 Thermal Analysis .......................................................................................... 129
3.10.4 Kinetics Study .............................................................................................. 131
3.10.5 Morphological Analysis ............................................................................... 135
3.10.6 Infrared Spectra Analysis ............................................................................. 137
3.10.7 Oil Uptake Study .......................................................................................... 140
3.11 Preparation and Characterization of Esterified Banana Trunk Fibers/Poly (Vinyl
Alcohol) Blend Film .............................................................................................................. 141
3.11.1 Reaction Scheme .......................................................................................... 141
3.11.2 FTIR Spectroscopy ....................................................................................... 141
3.11.3 Vibrational Studies ....................................................................................... 143
3.11.4 Vibrational Studies of Poly Vinyl Alcohol .................................................. 143
ix
3.11.4.1 Stretching Vibrations ..................................................................... 144
3.11.4.2 In-Plane and Out of Plane Bending ............................................... 148
3.11.5 Thermogravimetric Analysis (TGA) ............................................................ 150
3.11.6 Differential Scanning Calorimetry (DSC) .................................................... 153
3.11.7 Tensile Properties ......................................................................................... 157
3.11.8 Moisture Sorption Study .............................................................................. 158
3.11.9 Swelling Behaviour in Distilled Water ......................................................... 159
3.11.10 Morphology Analysis ................................................................................. 161
CHAPTER 4 : CONCLUSION .......................................................................................... 163
4.1 Conclusion ....................................................................................................................... 163
4.2. Novelty of This Work ..................................................................................................... 165
4.3 Future Work ..................................................................................................................... 165
References .............................................................................................................................. 166
List of Publications ................................................................................................................ 188
x
List of Figures
Page
Figure 1.1 Structure of cellulose……………………………………………………………....6
Figure 1.2 Structure of lignin……………………………………………………………….…6
Figure 1.3 Sugar monomer components of hemicellulose………………………………….…7
Figure 2.1 Structure of poly vinyl alcohol ............................................................................... 50
Figure 2.2 Structure of polyvinyl acetate……………………………………….……………50
Figure 2.3 Structure of Poly methyl methacrylate……………………………….…………..50
Figure 2.4 Structure of cis-1-4 polychloroprene…………………………….…………….…51
Figure 3.1 FTIR spectrum of unmodified banana trunk fiber…………….………………….58
Figure 3.2 FTIR spectra of modified banana trunk fibers, a)Alkaline treated,
b) actylation c).peroxide treated d) stearic acid treated and e) sulphonation……....……...…62
Figure 3.3 SEM micrograph of untreated banana trunk fibers…………………………….…64
Figure 3.4 Elemental Analysis spectrum of untreated banana trunk fiber……………...…....64
Figure 3.5 SEM spectra of banana trunk fibers after alkali treatment (BTF-1),acetylation
………….(BTF-2), peroxide treatment (BTF-3) and stearic acid treatment (BTF-4)….........66
Figure 3.6 Thermogravimetric decomposition processes of the fibers at a heating rate of 20
……….…°C/min.....................................................................................................................69
Figure 3.7 Derivative Thermogravimetric curves of banana trunk fibers after alkali treatment
.................(BTF-1), acetylation (BTF-2), peroxide treatment (BTF-3) and stearic acid
.................treatment (BTF-4)…………………............................………...…………………70
Figure 3.8 Derivative Thermogravimetric curve of banana trunk fibers after sulphuric acid
……….…treatment (BTF-5)….……..……………………...……….………………………70
Figure 3.9 Typical iso-conversional plot of Kissinger method for mercerized BTF…….…..73
Figure 3.10 Typical iso-conversional plot of Friedman method for acetylated BTF………..73
Figure 3.11 Typical iso-conversional plot of F-W-O method of peroxide treated BTF……..74
xi
Figure 3.12 Effect of pH on the adsorption of MR on banana trunk fibers (C0 = 500 mg/L,
………….....temp. = 25 - 27 ºC, stirring rate 150 rpm, contact time 120 min and weight of
………….....fibers=0.20 g)…………………....…….………….……………………………75
Figure 3.13 Effect of contact time on the adsorption of MR on banana trunk fibers (C0 = 500
…………...mg/L, temp. = 25 - 27 ºC, stirring rate 150 rpm, pH 3 and weight of fibers
…………..=.0.20 g) …………………………………......………………………………..…76
Figure 3.14 Effect of adsorbent dose on the adsorption of MR on banana trunk fibers (C0 =
………..….500 mg/L, temp. = 25 - 27 ºC, stirring rate 150 rpm and pH 3)…………………77
Figure 3.15 Effect of MR concentration on the adsorption of MR on banana trunk fibers
…………...(weight of fibers = 0.20 g, temp. = 25 - 27 ºC, stirring rate 150 rpm and pH
…………..3)………………………………………………………………..………………..78
Figure 3.16 Effect of pH on the adsorption of MR on the modified banana trunk fibers
(C0=500 mg/L, temp. = 25 - 27 ºC, stirring rate 150 rpm, contact time 120 min and
weight of fibers = 0.20 g)…….…………...………………………………….….81
Figure 3.17 Effect of MR concentration on the adsorption of MR on sulphuric acid treated
..banana trunk fibers (weight of fibers = 0.20 g, temp. = 25 - 27 ºC, stirring rate
..150 rpm and pH 3)……………..………………………..……………………..82
Figure 3.18 Effect of adsorbent dose on the adsorption of MR on the modified banana trunk
...fibers (C0 = 500 mg/L, temp. = 25 - 27 ºC, stirring rate 150 rpm and pH 3)…..83
Figure 3.19 Langmuir isotherm for MR sorption onto unmodified banana trunk fibers at
……………ambient temperature (25 - 27 ºC)…………………..……………………..….…85
Figure 3.20 Langmuir isotherm for MR sorption onto modified banana trunk fibers at
……………ambient temperature (25 - 27 ºC)…………………...………………………..…86
Figure 3.21Freundlich isotherm for MR sorption onto the unmodified banana trunk fibers at
………… ambient temperature (25 - 27 ºC)……………………………………….………..88
Figure 3.22 Freundlich isotherm for MR sorption onto the modified banana trunk fibers at …
……………ambient temperature (25 - 27 ºC)………………….……….………….………..88
xii
Figure 3.23 Pseudo first order for MR sorption onto banana trunk fibers at ambient
…………….temperature (25 - 27 ºC)…………………………………………………..……91
Figure 3.24 Pseudo second order for MR sorption onto banana trunk fibers at ambient
…………….temperature (25 - 27 ºC)………………………………...………………..…… 91
Figure 3.25 Dependence of qe of Cd(II), Cu(II), Fe(II) and Zn(II) with pH at 25 °C
...................(concentration = 10 mg/L, volume = 50 mL, BTF dosage = 0.2 g, agitation speed
……….…..= 150 rpm and contact time = 120 min)…………………….……...……………94
Figure 3.26 Dependence of qe of Cd(II), Cu(II), Fe(II) and Zn(II) with time at 25 °C
……………(concentration = 10 mg/L, volume = 50 mL, BTF dosage= 0.2 g, agitation speed
…………….=150 rpm and pH = 5)…………………….……………...….………...……….95
Figure 3.27 Dependence of qe of Cd(II), Cu(II), Fe(II) and Zn(II) with weight of fibers (g) at
………..….25 °C (concentration = 10 mg/L, volume = 50 mL, agitation speed = 150 rpm,
…………...time = 60 min and pH = 5)………………………………………………...…….96
Figure 3.28 Dependence of qe of Cd(II), Cu(II), Fe(II) and Zn(II) with concentration (mg/L)
…………...at 25 °C (BTF dosage = 0.2 g, volume = 50 mL, agitation speed = 150 rpm, time
………..….= 60 min and pH =5)……………………..……….………….....……….………98
Figure 3.29 The reaction scheme for the surface modification of Banana Trunk Fibers (BTF)
…………...with oleic acid……………..……………..……...……………………………..107
Figure 3.30 FTIR spectrum of (a) unmodified banana trunk fibers (UMBTF) and (b) Oleic
………..….Acid treated Banana Fibers (OGBTF)……...……….………...………………108
Figure 3.31 Removal of oil as a function of oil to water ratio by UMBTF, OGBTF, SGBTF,
………..….CGBTF and PGBTF…………...……………………….…….……..…………109
Figure 3.32 Removal of oil as a function of oil/kerosene ratio by UMBTF (Unmodified
…………...banana trunk fibers), OGBTF (Oleic Acid Treated Banana Fibers), SGBTF
…………..(Stearic Acid Treated Banana Fibers), CGBTF (Castor Oil Treated Banana
…………..Fibers) and PGBTF (Palm oil Treated Banana Fiber)………………….………110
Figure 3.33 Absorbance of unsaturated and organic compounds at 260 nm in weathered oil
……...........contaminated seawater for 100 day……........…………………………………111
xiii
Figure 3.34 Removal of DOC as a function of DOC/water ratio by UMBTF (Unmodified
……….…..banana trunk fibers), OGBTF (Oleic Acid Treated Banana Fibers), SGBTF
…….…….(Stearic Acid Treated Banana Fibers), CGBTF (Castor Oil Treated Banana
…………..Fibers) and PGBTF (Palm oil Treated Banana Fibers)…….…………..………112
Figure 3.35 Sorption of oil by OGBTF during five repeated biosorption cycles in the orbital
…………...shaker at 150 rpm, contact time 30 min each cycle of sorption……….……….113
Figure 3.36 Langmuir isotherm for (a) engine oil and (b) DOC sorption onto unmodified
..banana trunk fibers (UMBTF) and oleic acid grafted banana trunk fibers
.(OGBTF) at ambient temperature (25 - 27 ºC)…….………………………….117
Figure 3.37 Freundlich isotherm for (a) engine oil and (b) DOC sorption onto unmodified
………..….banana trunk fibers (UMBTF) and oleic acid grafted banana trunk fibers
…………..(OGBTF) at ambient temperature (25 – 27 ºC)……….……………....………. 118
Figure 3.38 Temkin-Pyzhev isotherm for (a) engine oil and (b) DOC sorption onto
…………...unmodified banana trunk fibers (UMBTF) and oleic acid grafted banana trunk
………..….fibers (OGBTF) at ambient temperature (25 - 27 ºC)…………...……..………119
Figure 3.39 Pseudo first order for engine oil sorption onto unmodified banana trunk fibers
…………..(UMBTF) and oleic acid grafted banana trunk fibers (OGBTF) at ambient
………...…temperature (25 - 27 ºC)...…………………………………………………..…123
Figure 3.40 Pseudo second order for engine oil sorption onto unmodified banana trunk fibers
……….….(UMBTF) and oleic acid grafted banana trunk fibers (OGBTF) at ambient
……….….temperature (25 - 27 ºC)………………….…………..…………...…....…….…124
Figure 3.41 Water sorption curves of BTF, MDBTF, SACCMDBTF and SAMDBTF……127
Figure 3.42 Moisture Sorption histogram of BTF, MDBTF, SACCMDBTF and
…………...SAMDBTF upon exposed to moisture for 5 days……..………...……...……...128
Figure 3.43 Plots of thermogravimetric analyses (a) TGA and (b) DTG curves of BTF,
…………...MDBTF, SACCMDBTF and SAMDBTF………..……………….………...…130
Figure 3.44 Typical iso-conversional plots of (a) Kissinger, (b) Friedman and (c) Flynn-
…………....Wall-Ozawa methods for SAMDBTF and SACCMDBTF…….….………….132
xiv
Figure 3.45 Scanning Electron Microscope Images of (a) BTF at 100 m, (b) BTF at 2 m,
…………...(c) SACCMDBTF at 100 m and (d) SACCMDBTF at 2m….………..…….136
Figure 3.46 Roughness images of (a) BTF and (b) SACCMDBTF………………………...137
Figure 3.47 Plot of FTIR spectra of (a) SAMDBTF (b) SACCMDBTF and (c) MDBTF…139
Figure 3.48 Sorption capacity of (a) SACCMDBTF and (b) SAMDBTF………………….140
Figure 3.49 FTIR spectrum of (a) unmodified banana trunk fibers (UMBTF) and (b) Oleic
…………...Acid treated Banana Fibers (OGBTF)………….....……………..…………….142
Figure 3.50 FTIR Spectrum of Poly vinyl alcohol………………………………………….146
Figure 3.51 FT-Raman Spectrum of Poly vinyl alcohol……………………………………147
Figure 3.52 Thermogravimetric analyses of (a) pure PVA and composites with different
…………....loading of oleic acid treated BTF (b) pure PVA and composites with different
…….…...…loading of stearic acid treated BTF……………...…………………………….152
Figure 3.53 Differential Scanning Calorimetry of (a) pure PVA and composites with different
………….. .loading of oleic acid treated BTF (b) pure PVA and composites with different
………….. .loading of stearic acid treated BTF…………..................................…………..156
Figure 3.54 Tensile strength of pure PVA and composites with different loading of fatty acid
…………...treated BTF…………………………………………..…...………..…………..157
Figure 3.55 Percentage of elongation at break of pure PVA and composites with different
………..….loading of fatty acid treated BTF…………..…………..………….…...………158
Figure 3.56 Moisture Uptake (%)of pure PVA and composites with different loading of fatty
………..… acid treated BTF………………….…………................……...………………..159
Figure 3.57 Degree of swelling (%) of pure PVA and composites with different loading of
………..….fatty acid treated BTF……….………...……………………….………………160
Figure 3.58 SEM photograph (a) Pure PVA, Composite with (b) 0.1 g, (c) 0.2 g, (d) 0.3 g, (e)
…………....0.4 g and (f) 0.5 g of oleic acid treated banana trunk fibers, respectively.........162
xv
List of Tables
Page
Table 1.1 Chemical composition and structural parameters of natural fibers……………….10
Table 2.1 Methods for calculating kinetic parameters using TGA data..................................36
Table 2.2 Optimal wavelength of MR solution at different pH……………………………...39
Table 2.3 Composition of BTF/PVA blend.............................................................................52
Table 3.1 Infrared spectrum data of banana trunk fiber...........................................................59
Table 3.2 Thermostability results of the fibers........................................................................71
Table 3.3 qe parameters for the adsorption of MR on banana trunk fibers (Weight = 0.20 g,
ambient temperature, concentration 500 mg/L and pH 3).......................................79
Table 3.4 Langmuir and Freundlich isotherm constants and correlation coefficients for
…………adsorption of MR on banana trunk fibers at ambient temperature…………...……89
Table 3.5 Comparison of the pseudo-first-order, pseudo-second-order adsorption rate
…………constants and calculated and experimental qe values obtained at different initial
…………MR concentrations……………………………….…………………..……………92
Table 3.6 Effect of change in [M2+
]/biomass ratio on biosorption of Cd(II), Cu(II), Fe(II) and
…………Zn(II) (metal concentration = 10 mg/L, pH 5, volume = 0.2 L, agitation speed =
…………150 rpm, time = 60 min)…………………………..…...………………………….99
Table 3.7 Langmuir and Freundlich isotherm constants and correlation coefficients for
…………biosorption of Cd(II), Cu(II), Fe(II) and Zn(II) at ambient temperature (25 °C)..101
Table 3.8 Comparison of the pseudo-first-order, pseudo-second-order adsorption rate
…………constants and calculated and experimental qe values obtained for a concentration of
…………10 mg/L of Cd (II), Cu(II), Fe(II) and Zn(II)……...………………………….….103
Table 3.9 qe values for untreated and treated BTF………………………………………….105
Table 3.10 Langmuir, Freundlich and Temkin-Pyzhev isotherm constants and correlation
…………..coefficients for sorption of engine oil………….……………………………….120
xvi
Table 3.11 Langmuir, Freundlich and Temkin-Pyzhev isotherm constants and correlation
……….…coefficients for sorption of DOC……………………….…………………….…121
Table 3.12 Comparison of the pseudo-first-order, pseudo-second-order adsorption rate
……….…constants and calculated and experimental qe values obtained for an initial weight
………….of 2.8 g of engine oil…………….………………………………………………125
Table 3.13 Activation energy of SAMBTF and SACCMBTF calculated by Kissinger
…………..method…………………………………………………………………………..133
Table 3.14 Average activation energy of SAMBTF and SACCMBTF calculated by Friedman
……….…and Flynn-Wall-Ozawa methods in a period of α = 0.2- 0.6……….……...……134
Table 3.15 Observed and theoretical wave numbers (cm-1
) and potential energy
………..…distribution (PED) for poly vinyl alcohol………………………………………148
Table 3.16 Thermostability results of pure PVA film and PVA/esterified banana dust ………
……….…composite film……………………………...……………………………………153
Table 3.17 Thermal characteristics by DSC of the PVA/FAGBTF composite films of
…………..different content of esterified fibers…………………………………………….155
xvii
List of abbreviations and symbols
Starting Materials and Products
BTF Unmodified banana trunk fibers
BTF-1 Sodium Hydroxide Treated Banana Trunk Fibers
BTF-2 Acytalated Banana Trunk Fibers
BTF-3 Peroxide Treated Banana Trunk Fibers
BTF-4 Stearic Acid Treated Banana Trunk Fibers
BTF-5 Sulphuric Acid Treated Banana Trunk Fibers
Cd(II) Cadmium (II) ion
CGBTF Castor oil Grafted Banana Trunk Fibers
Cu(II) Copper (II) ion
DOC Dissolved Organic Compound
FAGBTF Fatty Acid Treated Banana Trunk Fibers
Fe(II) Iron (II) ion
MDBTF Mechanically Damaged Banana Trunk Fibers
MR Methyl Red
PCP 1, 3 Cis – Poly chloroprene
PGBTF Palm Oil Grafted Banana Trunk Fibers
PVA Poly vinyl alcohol
PVAc Poly vinyl acetate
PMMA Poly methyl methacrylate
SAMDBTF Stearic Acid Treated Mechanically Damaged Banana Trunk
Fibers
SACCMDBTF Stearic Acid & Calcium Carbonate Mechanically Damaged
Banana Trunk Fibers
xviii
SGBTF Stearic Acid Grafted Banana Trunk Fibers
OGBTF Oleic Acid Grafted Banana Trunk Fibers
WOCS Weathered Oil Contaminated Seawater
Zn(II) Zink (II) ion
xix
Symbols
cm Centimeter
cm-1
Wavenumber
DSC Differential Scanning Calorimetry
DTG Derivative Thermal Gravimetry
EDX Energy Dispersive X-ray
FTIR Fourier Transform Infra-Red
g gram
hr hour
KBr Potassium Bromide
min Minutes
mg Miligram
mm Milimeter
NaCl Sodium Chloride
nm Nanometer
SEM Scanning Electron Microscope
SGVFF Simple general valence force field
PED Potential Energy Distribution
TG Thermal Gravimetry
TGA Thermogravimetry Analysis
ThBr Thorium Bromide
% Percentage
[M2+
] Concentration of ions
°C Celcius
qe Adsorption capacity
g Microgram
xx
PENGUBAHSUAIAN, PENCIRIAN DAN PENGGUNAAN
SERAT BATANG PISANG - Musa acuminate x balbisiana
Colla (ABB Group)
Abstrak
Tesis ini terbahagi kepada dua bahagian. Bahagian pertama membincangkan
penyingkiran melalui penjerapan (i) metil merah, suatu pewarna monoazo mutagenik,
(ii) ion logam berat, Cd(II), Cu(II), Fe(II) dan Zn(II) dan (iii) minyak tertumpah
daripada larutan akueus dengan menggunakan serat batang pisang (BTF)
takterubahsuai dan terubahsuai. BTF yang diubahsuai dengan asid sulfurik and asid
oleik menunjukkan penjerapan terbaik, masing masing, untuk metil merah dan
minyak. Proses keseimbangan digambarkan dengan baik oleh model isoterma
Freundlich dan kinetic pseudo tertib kedua. Bahagian kedua tesis ini membincang
penghasilan komposit hijau. BTF diubahsuai secara mekanikal menggunakan
pengisar berkelajuan tinggi dan serat yang dihasilkan (MDBTF) seterusnya
diubahsuai dengan (i) asid stearat (SAMDBTF) dan (ii) kalsium karbonat yang
diliputi dengan 5% (wt/wt ) asid stearat (SACCMDBTF). Kajian penyerapan minyak
telah dilakukan dan hasilnya menunjukkan bahawa SAMDBTF dan SACCMDBTF,
masing-masing, menyerap 9.5 g/g dan 18.3 g/g minyak enjin. Kajian ini
menunjukkan bahawa serat yang telah diubahsuai dapat menjerap minyak tumpahan
dengan baik. Tesis ini juga membincangkan penyediaan adunan campuran pelbagai
komposisi poli vinil alkohol (PVA) dan BTF yang diesterifikasi dengan asid lemak
(FAGBTF). Ciri-ciri PVA/FAGBTF dikaji dengan analisis terma gravimetri (TGA),
analsis pengimbasan kalorimetri pengkamiran (DSC), analsis imbasan mikroskop
elektron (SEM), spectroskopi FT-IR dan ujian tarikan universal. Didapati bahawa
peningkatan jumlah BTF dalam adunan memperbaiki sifat terma tetapi menurunkan
tahap peratusan penyerapan air dibandingkan dengan ciri-ciri PVA asli.
xxi
MODIFICATION, CHARACTERIZATION AND
UTILIZATION OF BANANA TRUNK FIBERS - Musa
acuminate x balbisiana Colla (ABB Group)
Abstract
There are two parts in this thesis. First part involves unmodified and modified
banana trunk fibers (BTF) for the removal of (i) methyl red, a mutagenic monoazo
dye, (ii) heavy metals ions, Cd (II), Cu (II), Fe (II) and Zn (II), and (iii) spilled oil in
aqueous solution. Sulphuric acid treated BTF and oleic acid treated BTF exhibited
the best sorption capacity for methyl red and spilled oil, respectively. The
equilibrium processes of these studies were described well by the Freundlich
isotherm and pseudo-second-order kinetic models. Secondly, this work discusses the
production of green composites. BTF were mechanically damaged using a high
speed blender and the resulting fibers (MDBTF) were treated with (i) stearic acid
(SAMDBTF) and (ii) calcium carbonate coated with 5% (wt/wt) stearic acid
(SACCMDBTF). Oil uptake study was conducted and the results reveal that
SAMDBTF and SACCMDBTF sorbed 9.5 g/g and 18.3 g/g of used engine oil at
equilibrium, respectively. This work reveals that the treated fibers were efficient
sorbents for oil spill recovery. The preparation of blends of various compositions of
poly vinyl alcohol (PVA) and fatty acid esterified BTF (FAGBTF) was also
discussed in this work. The characteristics of PVA/FAGBTF films were evaluated
by means of thermal gravimetric analysis (TGA), differential scanning calorimetry
(DSC), scanning electron microscopy (SEM), FT-IR spectroscopy and tensile tests.
It is found that the increased in the amount of BTF improved the thermal properties
but decreased the percentage degree of swelling of blends as compared to the
characteristics of pure PVA.
1
CHAPTER 1
INTRODUCTION
1.1 History of Fibers
The history of fibers is as old as human civilization. Traces of natural fibers have been
located to ancient civilizations all over the world. Flax fibers which are generally
considered as the oldest natural textile fiber were in use since 5000 BC. Previously the
usage of fiber was limited to natural fibers such as flax, cotton, silk, wool and plant based
fibers for different applications. Fibers are often divided into two categories; natural and
synthetic fibers. In the year 1665, the English researcher Robert Hooke describe about
physiological descriptions of minute bodies in his book which then lead to the production
of synthetic fiber. Starting from then till now, man made fiber production has reached an
estimate 24 million ton. Application of synthetic fibers vary; from home furnishings,
medicine, aeronautics, energy, industry, and more. Currently, fiber engineers modify the
nature of the natural fiber to improve its performance.
1.2 Types of Natural fiber
Plant, animal and mineral fibers fall into the natural fiber category. Examples of plant fibers
are banana, cotton, jute, and pineapple fibers. Animal fibers include coir, wool and silk to
name a few. Animal fiber is threadlike outgrowth of the skin and composed of keratin. The
only mineral based natural fiber is asbestos. Plant and animal based fibers are
biodegradable while asbestos is a non-biodegradable product. Synthetic fibers are derived
from extensive research to improve natural fibers. In general, synthetic fibers are created by
forcing, usually through extrusion process.
2
1.3 Properties of Natural and Synthetic Fibers
1.3.1 Natural Fibers
1.3.1.1 Physical Properties
Natural fibers can be classified several categories which are seed, bast, leaf and fruit
qualities. In composite application, the commonly used fibers are bast and hard leaf fibers
(Williams and Wool, 2000). Common bast fibers include hemp, jute, flax, ramie and kenaf
and examples of leaf fibers are sisal and banana. Joseph et al., (2000) concluded that the
strength characteristics of fiber depend on the properties of the individual constituents, the
fibrillar structure and the lamellae matrix. Thus, the structural components of the fibers
namely cellulose, hemicellulose and lignin have to be examined in order to obtain a better
understanding of the mechanical properties and durability of the fibers. Furthermore, fiber
strength, fiber fitness, the polymerization of the cellulose, cleanness or purity and
homogeneity of the sample has to be studied to have a clear understanding of the physical
properties of the fiber. Of late, the use of plant fibers as a reinforcing agent in fiber-
reinforced composite to replace synthetic fibers is receiving attention due to its advantages
such as high specific strength, cost, density, renewability, recyclability, abrasiveness and
biodegradability properties (Li et al., 2007; Bledzki and Gassan, 1999; Edeerozey et al.,
2007). Jähn et al. (2002) reported that plant fiber properties directly influence the physical
parameters of the fiber-reinforced composites. Currently, cotton, kenaf, sisal, flax, palm
oil, coir, arecanut and banana trunk fibers (BTF) acquire utmost significance, since
reinforced plastics, strings, cords, cables, ropes, mats, brushes, hats, baskets and fancy
3
articles such as bags are manufactured with those fibers (Mohan Rao and Mohana Rao,
2007). Furthermore, natural fibers are found to have high specific mechanical properties
which are comparable to those of traditional reinforcements (Hanselka and Herrmann,
1995). Thus, the intrinsic properties of natural fibers can satisfy the requests of the global
market (Herrmann and Hanselka, 1996) and gives less concern with environmental issues.
This fulfils the needs of industries such as automobile, shipbuilding and building industries
(Corrales et al., 2007). Thus natural fibers are deemed as potential substitute for non-
renewable synthetic fibers (Gandini et al., 2001).
1.3.1.2 Chemical Properties
Natural fibers are complex in structure. They are generally lignocellulosic, consisting of
helically wound cellulose micro fibrils in an amorphous matrix of lignin and hemicellulose
(Wang 2004). Table 1.1 shows the botanical composition of natural fibers. High cellulose
content which improves the mechanical properties is a desirable property of a fiber to be
used as reinforcement in polymer composites (Williams and Wool, 2000).
1.3.2 Properties of Synthetic Fibers
Synthetic fibers are created through a chemical process. Chemicals are forced into
spinnerets, which have tiny holes where the synthetic fibers are created. Polyester is the
most common synthetic fiber. Acetate, nylon, and spandex are several commonly used
synthetic fibers as fabrics. Synthetic fibers are commonly used as fabrics as they pose a
huge advantage over natural fibers due to its durable nature. The attractive forces between
fibers play a large part in determining it‘s properties.Due to its long chain, these interchain
forces are amplified far beyond the attractions between conventional molecules. Different
4
side groups on the fibers can lend to ionic bonding or hydrogen bonding between its own
chains. These stronger forces typically result in higher tensile strength and higher
crystalline melting points. In general, the physical properties of the fibers such as the tensile
strength increase with the fiber length and the crosslinking of the chains.
1.4 Lignocellulosic Fiber
By nature, lignocellulosic fiber consists of helically wound cellulose microfibrils in a
matrix of lignin and hemicellulose (Taj et al., 2007). Agricultural waste residues, such as
rice straw, banana stalk, and palm ash fall in this category. Plant fibers are now being used
to produce fuel, chemicals, enzymes, food (Khalil et al., 2006), automotive parts, in
construction applications and biocomposites (Ton-That and Denault, 2007). Approximately
2 × 1011
tons of lignocellulosics are produced every year, compared with 1.5 × 108 tons of
synthetic polymers (Khalil et al., 2006). Plant waste fibers are available through out the
year, abundant, renewable, and biodegradable. Since they cause environmental pollution
when left on the plantation floor, economic utilization of these fibers will be beneficial.
1.4.1 Advantage and Limitation of Lignocellulosic Fibers
Lignocellulosic fiber wastes can be used to develop materials with high performances; as
the National Academy of Science of USA puts it ‗‗hierarchical structures in biology as a
guide for new materials technology‘‘ (Ganan et al., 2007). This tendency is associated with
particular advantages that combine low density with good mechanical properties, low cost
and biodegradability. Natural fibres have attractive technical, economical and
environmental advantages that include: renewable source of energy, low abrasion, medium
thermal properties, high disposability, low energy consumption and low generation of
5
neutral carbon dioxide (Bledzki et al., 1998). They can be ideal competitors for the non-
renewable, expensive petroleum-based synthetic fibers in composite materials, particularly
in the automotive industry (Bledzki et al., 1998) and including building sectors (Kedari et
al., 2003).However, the applicability of these materials has been found to be limited due to
leaching of organic substances such as lignin, tannin, pectin and cellulose into the solution.
Furthermore, fibers are hydrophilic which causes fiber dispersion challenges and they are
sensitive to humidity. Other challenges of natural fibers are such as fiber inconsistency, low
impact strength and issue of stocking raw material for extended time period (Ton-That and
Denault, 2007). To overcome such problems, chemical treatment on solid adsorbents has
been used as a technique for improving physical and chemical properties of them and to
increase their adsorption capacity (Noeline et al., 2005).
1.5 Cellulose
Cellulose is the most abundant organic chemical on the face of the earth. It is a glucan
polymer of D-glucopyranose units, which are linked together by α-1,4-glucosidic bonds.
The building block for cellulose is actually cellobiose, since the repeating unit in cellulose
is a two-sugar unit. Cellulose molecules are randomly oriented and have a tendency to form
intra- and intermolecular hydrogen bonds. As the packing density of cellulose increases,
crystalline regions (65%) are formed. Lower packing density region is referred to as
amorphous cellulose. The molecular chains pack in layers that are held together by weak
Van der Waals forces. The layers consist of parallel chains of anhydroglucopyranose units
and the chains are held together by intermolecular hydrogen bonds. There are also
intramolecular hydrogen bonds between the atoms of adjacent glucose residues. There are
6
several types of cellulose in wood: crystalline and noncrystalline and accessible and
nonaccessible. Accessible and nonaccessible refer to the availability of the cellulose to
water and microorganisms. The surfaces of crystalline cellulose are accessible but the rest
of the crystalline cellulose is nonaccessible. Most of the noncrystalline cellulose is
accessible but part of the noncrystalline cellulose is covered with both hemicelluloses and
lignin that it becomes nonaccessible. Concepts of accessible and nonaccessible cellulose are
very important in moisture sorption, pulping, chemical modification, extractions, and
interactions with microorganisms (Rowell et al., 2005).
1.6 Lignin
Lignins are amorphous and highly complex. Lignin is a polymer of aromatic phenylpropane
units. The precursors of lignin biosynthesis are p-coumaryl alcohol, coniferyl alcohol and
sinapyl alcohol. Softwood lignin has a methoxyl content of 15–16%; hardwood lignin has a
methoxyl content of 21%. Lignin is produced through phenol derivatives and the three
basic building blocks of guaiacyl, syringyl, and p-hydroxyphenyl moieties. Lignin is
distributed throughout the secondary cell wall, with the highest concentration in the middle
lamella. 70% of the lignin is located in the cell wall (Rowell et al., 2005).
Figure 1.1: Structure of cellulose
Figure 1
(Beg, 2007)
7
1.7 Hemicellulose
Hemicellulose is a branched heteropolymer. Hemicellulose has a random, amorphous
structure with little strength and present along the cellulose. It is made up of monomers
such as xylose, mannose, galactose, rhamnose, arabinose, mannuronic acid and galacturonic
acid. Hemicelluloses contain large amount of D-pentose sugars and small amounts of L-
sugars; consists of shorter chains of sugar units; embedded in the cell walls of plants and
bind with pectin to cellulose to form a network of cross-linked fibres. Hemicelluloses
include xylan, .glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan.
Figure 1.2: Structure of lignin
Figure 2
(Beg, 2007)
Chief
monomer unit
8
Figure 1.3: Sugar monomer components of hemicellulose (Rowell et al., 2005)
1.8 Chemical Properties of Natural Fibers
Natural fibers are complex in structure. They are generally lignocellulosic, consisting of
helically wound cellulose micro fibrils in an amorphous matrix of lignin and hemicellulose
(Wang 2004). Table 1.1 shows the botanical composition of natural fibers. High cellulose
content which improves the mechanical properties is a desirable property of a fiber to be
used as reinforcement in polymer composites (Williams and Wool, 2000).
9
1.9 Moisture Absorption Characteristics
The main disadvantage concerning the use of natural fibers is their susceptibility to
moisture uptake (Sreekala et al., 1997a; Sreekala et al., 1997b; Selzer and Friedrich, 1995;
Rana et al., 1997). High moisture sorption capacities of natural fibers adversely affect the
adhesion with hydrophobic matrix (Bessadok et al., 2007; Satyanarayana et al., 2006). This
results in material degradation, loss of strength and causes weaker adhesion in the
fiber/matrix interface, thus compromising some of the mechanical properties of the
manufactured composite. Thus, the fiber surface must be cleaned and chemically modified
to decreases the rate of moisture absorption in a composite (Yuan et al., 2002).
10
Table 1.1 Chemical composition and structural parameters of natural fibers
Fibers %
Cellulose
%
Hemi-Cellulose
% Lignin % Ash
%
Extractives
Moisture
Content
Reference
Jute 61 -71.5 13.6- 20.4 12 – 13 - - 12.6 Mohanty et al., 2000
Flax 71 -78.5 18.6 – 20.6 2.2 1.5 2.3 10.0 Mohanty et al., 2000
Hemp 70.2 -74.4 17.9 – 22.4 3.7-5.7 2.6 3.6 6.2 Mohanty et al., 2000
Banana
Trunk
24.2 – 38.3 11.1 –18.9 13.8-16.4 8.6 4.5 9.7 Bilba et al., 2007
Sisal 67-78 10-14.2 8-11 - - 11 Mohanty et al., 2000
Cotton 82.7 5.7 - - - - Mohanty et al., 2000
Coir 36 -43 36-43 41 – 45 - - 8 Mohanty et al., 2000
11
1.10 Chemical Treatment of Natural Fibers
Chemical modifications of fibers are carried out to improve the physio-chemical properties
of the fibers. Chemical treatment of the fibers can clean the fibers surface, chemically
modify the surface, stop the moisture absorption process and increase the surface roughness
(Edeerozey, et al., 2007). Modifications can be carried out on natural fibers as they possess
hydroxyl groups from cellulose, hemi-cellulose and lignin. The hydroxyl groups possibly
have interaction via the hydrogen bonding within the molecules and this reduces the
activity towards the matrix. A chemical modification therefore activates these groups and
also introduces new moieties that can effectively interlock with the matrix. Thus, various
studies on the treatment of different types of plant fibers to improve their properties have
been carried out. Many works have been reported with regards to the modification of
natural fibers (Barkakty, 1976; Bisanda and Anshell, 1991). Among the popular treatments
carried out by various researchers are alkali treatment (Ray et al., 2001; Bledzki et al.,
2004; Aziz and Ansell, 2004; Mishra et al., 2001; Sreekala and Thomas, 2003), acetylation
(Sreekala and Thomas, 2003; Mohanty et al., 2000), peroxide treatment (Joseph et al.,
2002; Paul et al., 1997), graft co-polymerisation (Karmaker and Youngquist, 1996) silane
treatment (George et al., 1998; Bataille et al., 1989) and benzoylation
(Joseph et al., 1996;
Nair et al., 1996).The different surface chemical modifications of natural fibers have
achieved various levels of success in improving fiber strength, fiber fitness and fiber-matrix
adhesion in natural fiber composites. Various fibers surface modifications were carried out
to reduce the hydrophilicity and thereby decreasing the sorption characteristics of oil palm
fibers (Sreekala et al., 2003). The data obtained from their study suggest that treatment
reduces the water uptake at all temperatures. The decrease is due to its physical and
12
chemical changes occurred to the fibers on modifications. Edeerozey, et al., 2007 was
found that the alkalization treatment has improved the mechanical properties of the kenaf
fibers significantly as compared to untreated kenaf fibers. Mercerization, acetylation, and
resorcinol / hexamethylenetetramine (R/H) treatments have been applied to sisal fibers in
order to improve their adhesion in composites materials (Martins et al., 2006). Treatment
with acetic anhydride to bring acetylation of the cellulose fibers has also been proved to be
an effective means of modifying cellulose fibers surface. Brief descriptions of several
chemical modifications that were used in this study are discussed briefly in the following
sections.
1.11 Surface Chemical Modifications of Natural Fibers
1.11.1 Mercerization
Mercerization is currently the most common chemical treatments of natural fibers when
used to reinforce thermoplastics and thermosets. Mishra et al., 2001 and Ray et al., 2001
treated sisal, flax and jute fibers, respectively with 5% aqueous NaOH at room temperature.
These researchers concluded that alkali treatment increased in amorphous cellulose and
decreased crystalline cellulose. Alkaline treatment disrupts the hydrogen bonding in the
network structure, hence increases fiber surface and roughness (Bilba et al., 2007) which
results in better mechanical interlocking (Valadez-Gonzalez et al., 1999). This increases the
specific surface area of the fibers, making the hydroxyl groups of cellulose macromolecules
more easily accessible and increases the number of possible reaction sites (Valadez-
Gonzalez et al., 1999). This treatment also removes a certain amount of lignin,
hemicelluloses, wax and oils covering the external surface of the fiber cell wall (Pothan et
al., 2006), luminium s cellulose and exposes the short length crystallites (Mohanty
13
et al., 2001). The following reaction (Scheme 1.1) takes place as a result of alkali
treatment; addition of aqueous sodium hydroxide (NaOH) to fiber promotes the ionization
of the hydroxyl group to the alkoxide (Agrawal et al., 2000).
Fiber- OH + NaOH Fiber-Ona + H2O
Scheme 1.1
1.11.2 Acetylation
Acetylation of natural fibers is a common method causing plasticization of cellulosic fibers
which introducing an acetyl functional group (CH3COO–) into the fibers. However, the
reactions produce acetic acid (CH3COOH) as by-product and have to be removed from the
lignocellulosic material before the fiber is used. Chemical modification with acetic
anhydride (CH3-C (=O)-O-C (=O)-CH3) substitutes the hydroxyl groups of cellulose, hemi-
cellulose and lignin with acetyl groups to be come hydrophobic (Hill et al., 1998). The
reaction of acetic anhydride with natural fiber is shown in Scheme 1.2. Acetylation
increases the dimensional stability of composites and reduces the hygroscopic nature of
natural fibers. Acetylation of sisal fibers was investigated Mishra et al. 2003. Sisal fibers
were immersed in 5 % and 100 % NaOH (1 hour at). Next, the mercerized fibers were
soaked in glacial acetic acid for 1 hour at 30°C, separated by decantation and then soaked
in acetic anhydride containing one drops of concentrated H2S04 for 5 minutes. Manikandan
Nair et al. 2001 treated sisal fiber in 18% NaOH solution, then in glacial acetic acid (1
hour) and finally in acetic anhydride containing two drops of concentrated H2SO4 for 1
14
hour. The treated surface of sisal fiber was found to be very rough and had voids that would
provide better mechanical interlocking with polymer matrix (Li et al., 2007).
Fiber – OH + CH3-C(=O)-O-C(=O)-CH3 Fiber-OCOCH3 + CH3COOH
Scheme 1.2
1.11.3 Peroxide Treatment
Commonly, the chemicals used for peroxide treatment in natural fiber‘s surface
modification are benzoyl peroxide (BP, ((C6H5CO)2O2) and dicumyl peroxide (DCP,
(C6H5C(CH3)2O)2). Peroxides have ROOR functional groups which contain the divalent ion
O–O and tend to decompose easily to free radicals of the form RO. The RO groups then
reacts with the hydrogen group of the matrix and cellulose fibers. Sreekala et al. (2003)
treated oil palm fibers with BP or DCP in acetone for 30 minutes after alkali pre-treatment
and concluded that thermal stability of fibers increased after treatment. The tensile strength
of peroxide treated short sisal fibers reinforced polyethylene composites also increases
(Joseph et al., 1996) and the hydrophobicity decreased (Paul et al., 1997) upon treatment.
1.11.4 Stearic Acid Treatment
Stearic acid (CH3(CH2)16COOH) treated fibers in 1 % ethyl alcohol was investigated in
Paul et al., 1997 and Zafeiropoulos et al. (2002). It was concluded that this treatment
removed non-crystalline constituents of the fibers, hence alters the fiber surface
morphology and topography. Zafeiropoulos (2002) also observed that treated flax fibers
were found to be more crystalline than the untreated ones and stearation decreased the fiber
surface free energy. Banerjee et al. (2006) used saw dust fibers, stearic acid, 2 drops of
15
concentrated H2SO4 in 100 mL of n-hexane and refluxed this mixture in a Dean–Stark
apparatus at 65 °C for 6 hour. The resulting material was found to be suitable for oil spill
recovery.
1.11.5 Acid Treatment
Alvarez et al. (2004) treated saw dust fibers using 8N of sulphuric acid at 150 °C for 30 and
120 minutes. The results obtain shows that the sulphuric treated fibers are thermally more
stable than the parent lignocellulosic material. Furthermore, upon carbonization at 900 °C,
the acid treated saw dust yields a char with a well-ordered honeycomb structure. Activated
carbon pretreated by heating with luminium acid and nitric acid at high temperature to
evaluate their performance on hexavalent luminiu removal from aqueous phase. The
obtained results indicated that the treated activated carbon is an efficient sorbent for the
removal of (Cr (VI)). Hydrochloric acid treated date palm tree fiber (0.3, 0.9 and 1.6N for 1
hour at 100°C) resulted in deterioration in mechanical properties (Alawar et al., 2009).
1.12 Research of Banana Trunk Fibers
There are only limited reports on banana trunk fibers available in literature. Idicula et al.
(2005) reported that user-friendly and cost-effective composite materials possessing
appropriate stiffness and damping behaviour can be obtained by hybridising banana fibers.
The role of fiber/matrix interactions of chemically modified banana fibre/polyester
composites was studied by Pothan et al., 2006 and concluded that chemical modification
improves the storage modulus of these composites. Sapuan et al. (2006) developed
composite woven banana fibre reinforced epoxy composites for household utilities. Deepa
et al. (2010) extracted cellulose nanofibers from banana fibers via a steam explosion
16
technique. The nanofibers were found to enhance thermal properties as compared to the
untreated fibers. Polylactic acid (PLA)/ banana fiber biocomposites were fabricated using
melt compounding technique by Majhi et al (2010). The obtain results indicate that the
improved interfacial adhesion in compatibilized and plasticized systems. Composites were
prepared with maleic anhydride modified banana fibers in polypropylene by Chattopadhyay
et al. (2010). The composite exhibited an increase in impact strength, flexural strength,
flexural modulus and tensile strength. Banana fibers were treated with alkaline pulping and
steam explosion to produce banana fibers and banana microfibrils by Ibrahim et al., 2010.
The results obtained shows that the banana microfibrils has better compatibility and
enhanced mechanical properties as compared to banana fibers. Hybrid composites of
Polypropylene (PP) reinforced with intimately mixed short banana and glass fibers were
fabricated using Haake twin screw extruder followed by compression molding with and
without the presence maleic anhydride grafted polypropy-lene (MAPP) as a coupling agent
by Samal et al. (2009). The composite exhibited an increase in tensile, flexural and impact
strength and a decrease in water absorption rate. The use of banana fibers composites for
automotive and transportation application were studies (Herrera-Estrada et al., 2008). The
banana fiber/epoxy composites were found to yield a flexural strength of 34.99 Mpa and
compressive strength of 122.11 Mpa. The alkaline pretreated composite exhibited an
improved environmental exposure resistance. Joseph et al. (2008) treated banana fibers
withsodium hydroxide, silanes, cyanoethylation, heat treatment, and latex treatment. The
thermal stability of the treated fibers improved due to its physical and chemical changes
induced by the treatments. Hameed et al. (2008) used banana stalk waste as a sorbent to
sorb methylene blue. The Langmuir isotherm was demonstrated to provide the best
correlation for the sorption of methylene blue with an adsorption capacity of 243.90 mg/g.
17
The author and his principle supervisor have also published several papers pertaining to
banana trunk fibers (Mas Haris and Kathiresan, 2009; Kathiresan and Mas Haris, 2010a;
Kathiresan and Mas Haris 2010b; Kathiresan et al., 2010c, Mas Haris and Kathiresan,
2010).
1.13 Pollution
Pollution is defined by introduction of contaminant into the environment due to human
activities or natural disasters. A major reason for pollution is industrialization. Rapid
progress in industrial activities during recent years has led to the discharge of
unprecedented amount of wastewater containing synthetic dyes, heavy metals and fossil
fuels which pollutes our waters and consequently causes harm to human and other living
organisms. A majority of the used dyes are azo reactive dyes (Leechart, et al, 2009). These
are bright color dyes due to the presence of one or several azo (─N═N─) groups associated
with substituted aromatic structures (Forgacs, et al., 2004). Effluents from textile, leather,
food processing, cosmetics, paper and dye manufacturing industries are some examples of
the sources of discharged azo dyes (Bhatnagar and Jain, 2005). These dyes or their
breakdown products are toxic to living organisms (Chung et al., 1981). Furthermore, dyes
in wastewater are difficult to remove because they are stable to light, heat and oxidizing
agents. In short, they are not easily degradable (Jain and Sikarwar, 2008). Heavy metals are
alsodeposited into our ecosystems
(Sanyahumbi et al., 1998). These metals are not
biodegradable and known to cause severe dysfunction of the kidney, reproductive system,
liver, brain and central nervous system (Manahan, 2004). Fossil oil is beyond a doubt
currently the most important raw material and energy source worldwide. There have been
numerous occasions whereby oil was unintentionally introduced into the environment
18
during production, transportation and refining process causing adverse effect on sea life and
human economic activities (Boopathy 2000). Furthermore, oil spill may also cause strong
odor to be felt miles away and the excessive growth of green algae may alter the color of
sea and landscape (Annunciado et al., 2005).
1.14 Waste Water Treatment
Several methods for removing heavy metal ions such as chemical precipitation, electro-
deposition, ion exchange, reverse osmosis and adsorption have been used to treat
wastewater
1.14.1 Chemical Precipitation
Selected chemicals are added to form coagulate particles and the particles are allowed to
settle down. The treated water is then decanted to remove the contaminants and is
appropriately disposed of or reused. This technique can be employed to remove heavy
metals, fats, oils and greases, suspended solids phosphorus, fluoride, ferrocyanide and other
inorganics compounds. The chemical precipitation is the most economical technique but is
inefficient for dilute solution.
1.14.2 Electro-Deposition, Ion Exchange and Reverse Osmosis
Electro-deposition is a technique that deposits dissolved or suspended material by an
electric field on an electrode. This technique is usually employed for the removal of heavy
metal from water source (Dini, 1993). Ion exchange technique in waste water treatment is
used for softening and nitrate removal. Ion exchange is a reversible chemical reaction
wherein an ion from solution is exchanged for a similarly charged ion attached to an
19
immobile solid particle. Reverse osmosis demonstrates a high heavy metal rejection,
compared to ion exchange but operates on a continuous mode with low reagent
consumption. However, these techniques have rather maintenance and operation costs and
subject to fouling (Kathiresan and Mas Haris, 2010).
1.14.3 Adsorption
Adsorption techniques are generally categorized as physical adsorption, chemisorption or
electrostatic adsorption. Weak molecular forces, namely Van der Waals forces, provide the
driving force for physical adsorption. Chemical reaction on the other hand forms a chemical
bond between the compound and the surface of the solid in chemisorption. Electrostatic
adsorption involves the adsorption of ions through Coulombic forces, and is normally
referred to as ion exchange. Adsorption techniques are generally considered as the preferred
means for removing and purifying organic substances due to their high efficiency and
ability to separate a wide range of chemical compounds (Imamura et al., 2002; Gemeay et
al., 2002; Holzheu and Hoffmann; 2002; Ofomaja and Ho, 2006).This has prompted
enormous research interest in the use of agricultural waste as starting materials because of
their low-cost and widespread availability.
1.14.3.1 Adsorption of Dyes Using Natural Fibers
Some examples of agrowaste that have been used for the removal of dyes are palm kernel
fibers (Ofomaja, 2008) coir pith
(Namasivayam et al., 2001) sugarcane bagasse (Azahar. Et
al., 2005), banana peel (Annadurai et al., 2002), peanut hull (Gong et al.,2005), rice bran
20
and wheat bran (Xue, et al., 2008), rice husk (Lakshmi et al., 2009) tea waste (Tamez
Uddin et al., 2009), waste apricot (Onal et al., 2007), rubber seed coat (Hameed and Daud,
2008) coconut shell (Singh et al., 2008), apple pomace and wheat straw (Robinson et al.,
2002a), halzelnut shell (Dogan et al., 2009), plum kernel (Tseng, 2007), corncob and barley
husk (Robinson et al., 2002b) , bamboo
(Hameed et al., 2007), grass waste
(Hameed,
2009), pumpkin seed hull (Hameed and El-Khaiary, 2008) and garlic peel (Hameed and
Ahmed, 2009).
1.14.3.2 Adsorption of Heavy Metals Using Natural Fibers
Examples of low-cost fibers for the adsorption of heavy metals are pine bark (Al-Asheh and
Duvnjak, 1998), cork and yohimbe bark (Villaescusa et al., 2000), spent grain
(Low et al.,
2000), peanut hull pellets (Johnson et al., 2002), rice milling by-products (Tarley and
Arruda, 2004), grape stalk waste (Martinez et al., 2006) pectin rich fruit wastes (Schiewer
and Patil, 2008), biowaste from fruit juice industry (Senthilkumaar et al., 2000). Agave
Americana (Hamissa et al., 2010), banana trunk fibers (Kathiresan and Mas Haris, 2010),
coconut fibers (Igwe et al., 2008), oil palm fibers (Isa et al., 2008), wheat barn (Farooq et
al., 2010), coir (Cornad and Hansen, 2007; Shukla and Pai, 2005) and juniper fiber (Min et
al., 2004)
1.14.3.3 Adsorption of Oil Using Natural Fibers
An efficient methods for combating oil spill as reported in literature is using fibers derived
from kapok tree (Ceiba pentandra) as a natural hollow hydrophobic–oleophilic sorbent
(Lim and Huang, 2007; Abdullah et al., 2010). Recently, barley straw waste was also used
as an application on oil spill clean up (Husseien et al., 2009). Other low cost fibers used for
21
oil spill recovery are wool fibers (Rajakovic et al., 2007), cotton grass (Suni et al., 2004),
reed canary grass, flax and hemp fiber (Pasila, 2004), peat excavation (Suni et al., 2004)
and saw dust (Banerjee, et al., 2006).
1.15 Composite
A composite is a multiphase material that is artificially made, as opposed to one that occurs
or forms naturally. In addition, the constituent phases must be chemically dissimilar and
separated by a distinct interface (Callister, 2006). Composites are obtained when two or
more distinct constituents are combined. The distinct constituents are a reinforced phase of
strong material, often fibrous in nature, embedded within a continuous matrix phase which
is usually weaker and more compliant. This combination derives a new material with
enhanced properties and is distinctively different from those of the individual components.
Of late, many researchers are developing composite materials made from natural fiber and
resins due to the increased of environmental awareness and interest in long term
sustainability of material.
1.15.1 Biocomposite
Biocomposites are composite materials made from natural fiber and petroleum-derived
non-biodegradable polymers such as polypropylene, polyethylene or biodegradable
polymers such as polylactic acid (PLA) and polyhydroxyalkanoates (PHA). Biodegradable
or synthetic polymers reinforced with natural fibers are a viable alternative to glass fiber
composites. Biocomposites or biodegradable composites are designed in the hope to
contribute to the reduction of environmental load placed upon by the disposal of used
plastic product. These biocomposite plastic can be resolved into water and carbon dioxide
22
through an enzymatic reaction by microorganisms. The polymer chains are enzymetically
cleaved, and the portions that are small enough are transferred into cells and consumed
(Kale et al., 2007). Biocomposite materials can lumin the requirements of various
applications such as non-food packaging or short – lived application where long – lasting
polymers are not entirely adequate. The need for biodegradable composites stimulated
extensive research into the design of composites reinforced with natural fibers such as flax,
jute, straw, wood fiber, rice husks, wheat, barley, oats, rye, sugar cane, bamboo cane, sisal,
paper-mulberry, pineapple leaf fiber and papyrus (Taj et al., 2007). Most of the initial
efforts in this area have focused on the replacement of potentially hazardous chemical
materials with alternative natural fibers that are often readily available as agricultural by-
products (Savastano Jr. et al., 2000) or industrial wastes (Savastano Jr. et al., 2001), with
little or no current economic value.
1.15.2 Green Composite
Green composite is defined as biocomposite produced from plant derived fiber and
crop/bio-derived plastic and are likely to be more eco-friendly (John and Thomas, 2008).
Netravali and Chabba (2003) reported that research effort is being harnessed in developing
a new class of fully biodegradable green composites by combining fibers with
biodegradable resins. There are several reports on the preparation of green composites
(Corrales et al., 2007; Huang and Netravali, 2009; Shih et al., 2009; Liu and Erhan, 2008;
Huang and Netravali, 2007; Gomes et al., 2007; Takagi and Asano, 2008; Asasutjarit et al.,
2009). The major attractions about green composites are that they are environmentally
friendly, fully degradable and sustainable. At the end of their life span, they can be easily
disposed of or composted without harming the environment.
23
1.15.2.1 Preparation of Green Composites
Many researchers are attempting to producing green composite for various applications.
Corrales et al. (2007) chemically modified jute fibers using jute fibers to produce green
composite. The chemical modification was carried out in pyridine or dichloromethane
solvents using oleoyl chloride as coupling agent. Jute fibers were vacuum dried at 90° C for
24 hr. Reactions were carried out in a dry nitrogen atmosphere by suspending the fibers in
the dry solvent. The results obtained indicated that the chemical modification of cellulosic
fibers with a fatty acid coupling agents improves the wetting and adhesion of the fiber
surface. Biodegradable green composites made using bamboo micro/nano-fibrils and
chemically modified soy protein resins were prepared by Huang and Netravali (2009). The
objective of their study was to develop fully biodegradable and environment-friendly green
composites possessing moderate strength and stiffness. Shih et al. (2009) prepared using
biodegradable green composites reinforced by the fiber recycling from disposable
chopsticks and poly lactic acid. The results obtained indicate an improvement on the
mechanical or thermal properties of the reinforced composite. Fully environment-friendly,
sustainable and biodegradable green composites were fabricated using modified soy protein
concentrate resins and flax yarns and fabrics (Huang and Netravali, 2007). The produced
composite produced improved mechanical properties. A review by Ashori (2008)
concluded that wood–plastic composites are a promising green-composite for automotive
industries applications due to their superior strength/weight and stiffness/weight ratios.
These composites are normally produced by mixing plant fiber with polymer, or by adding
wood fiber as filler in a polymer matrix. The mixed samples are pressed or molded under
high pressure and temperature. Additives such as colorants, coupling agents, stabilizers,
24
blowing agents, reinforcing agents, foaming agents and lubricants help tailor the end
product to the target area of application (Ashori, 2008). Dobircau et al. (2009) prepared
new composites materials, having waste cotton fiber as reinforcement in wheat flour. The
mixture was extruded with a single-screw extrusion machine at 110 °C and at a rotating
speed of 40 rpm. The obtained pellets are homogenized and were extruded again at the
similar temperature but with higher rotating speed of 70 rpm to form the desired film.
Finkenstadt et al. (2007) produced poly lactic acid green composites using oilseed co-
products as fillers. The composites were compounded using a twin-screw extruder with a
screw speed of 130 rpm and was the melt temperature was at 160 °C. Poly lactic acid was
also used by to produce green composite using chicken feather as reinforcement material
(Cheng et al., 2009). All samples were prepared by extrusion and injection molding
methods. The chicken feather and poly lactic acid was palletized using twin-screw micro
extruder with a temperature of 180 °C. The screw speed and the mixing duration were set to
be 100 rpm and 10 min, respectively. A Thermo Hakke small scale injection molding
machine was used to produce dumbbell-shape composite samples. Green composites and
nano composites were prepared by Liu and Erhan (2008) using luminium soyabean oil.
Epoxidized soyabean oil and 1, 1, 1-tris (p-hydroxyphenyl) ethane triglycidyl ether were
mixed in the ratio of 1:0.33 (by weight) at 55 ◦C for 30 min. The mixture was prepared with
Aerosil R805 and degassed for 15 min at 55 °C. Designated flax fiber was added to the
mixture with mechanical stirring for 15 min. After the mixture cooled to room temperature,
curing agent was added with mechanical stirring and then transferred into a designated
mold. The flexural modulus and tensile modulus of the composites increased proportionally
with the increase in 1, 1, 1-tris (p-hydroxyphenyl) ethane triglycidyl ether. Takagi and
Asano (2008) prepared environmentally-friendly green composites which were fabricated
25
from starch-based, dispersion-type biodegradable resin and cellulose nanofibers. The
preparations of composites were carried out by mixing the biodegradable resin and
cellulose. Upon removing excess water, the composites were dried in at 105 °C in air and
vacuum. Nanofibers with loading of 70% (wt/wt) were added by hot pressing at a
temperature of 140 °C and pressure between 10 – 50 Mpa. The results obtained showed an
increase in flexural strength and modulus with increasing molding pressure. These
enhanced mechanical properties are attributable partially to increased density. Moreover,
the mixing treatment applied to a water solution of dispersion-type resin and low-speed
stirrer treatment plays an important role in the strengthening of nanofiber-reinforced
composites.
1.16 Industrial Polymers
To date, almost all industry uses polymers in one form or another. The transportation,
electronics, construction, medical and aircraft industries rely on these materials to provide a
higher quality product at lower cost than conventional materials, such as metals, wood,
concrete or rubber. Industrial polymers structures are based on chemical elements such as
carbon, oxygen, hydrogen, nitrogen, chlorine and sulfur. These elements are extracted from
the air, water, gas, oil, coal, and even from living plants. Researchers past and present took
these elements and combined them through various chemical reactions to create an almost
unending series of combinations to produce the wide variety of polymers.
1.16.1 Poly Vinyl Alcohol
Poly vinyl alcohol (PVA) is a polymer of great interest in the commercial sector because of
its various applications (Hassan and Peppas, 2000). PVA is a versatile polymer with many
