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Transcript of Cd5500 Ainun Jariah Binti Sansuri
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SYNTHESIS AND SWELLING BEHAVIOR OF BENTONITE BASEDSUPERABSORBENT POLYMER COMPOSITES
AINUN JARIAH BINTI SANSURI
A report submitted in partial fulfillment of the
requirement for the award of degree the of
Bachelor of Chemical Engineering
Faculty of Chemical & Natural Resources Engineering
Universiti Malaysia Pahang
DECEMBER 2010
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ABSTRACT
A novel superabsorbent polymer composite (SPC) was synthesized by solution
polymerization reaction of partially neutralized acrylic acid (AA) and acrylamide
(AM) on bentonite micropowder using N,N-methylenediacrylamide (MDA) as
croslinker and ammonium peroxodisulfate (APS) as an initiator in aqueous solution.
Poly (acrylamide-co-acrylic acid) [poly (AM-co-AA)]-based bentonite SPC were
prepared by varying the cross-linking agent composition amount in the range of 0.00%
to 1.80%. The effect of Bentonite as filler in weight percentages range of 0.00% to
1.40% on the water absorbency of the hydrogels was also studied by keeping two
monomers content constant. The synthesized hydrogels were characterized by FTIR
dan SEM. The effect of amount of Bentonite and crosslinker on the water absorbency
of AM-AAc-Bentonite was investigated to different physiological fluids which are;
deionized water, NaOH solution pH 13.75 and HNO3 solution pH 2.10. An optimum
condition which is highest percentages of swelling behavior were obtained with
bentonite composition at about 1.00% wt, crosslinker composition in range 1.20-
1.40% wt and the best fluid immersed in distilled water. The water absorbency of
poly(AA-co-AM)/bentonite was found to be 3821.57, 822.15 and 675.72g H2O g in
distilled water, alkali solution and acid solution.
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ABSTRAK
Sebuah novel komposit polimer superabsorbent (SPC) disintesis dengan
menetralisiki pempolimeran larutan asid akrilat (AA) dan akrilamida (AM) terhadap
serbuk micro Bentonite dengan menggunakan N,N-methylenediacrylamide (MDA)
sebagai agen penyambung, dan peroxdisulfate ammonium (APS) sebagai pemangkin
dalam larutan cecair. Poli(asid akrilat-co-akrilamida)[poli(AA-co-AM)] SPC
berasakan Bentonite dikaji dengan menvariasikan jumlah berat komposisi agen
penyilang dalam julat diantara 0.00% hingga 1.80%. Pengaruh komposisi Bentonite
sebagai agen pemanbah dalam julat diantara 0.00% hingga 1.40% terhadap kadar
serapan air di dalam larutan cecair dengan memalarkan kandungan monomer-
monomer yang digunakan. Sifat sistesis hidrogel dibuktikan dengan menggunakan
FTIR dan SEM. Pengaruh jumlah Bentonite dan agen penyilang terhadap kadar
penyerapan AM-AAc-Bentonite dikaji di dalam cecair fisiologi yang berbeza iaitu air
deionisasi, larutan NaOH dan larutan HNO3 dengan nilai pH 13.75 dan 2.10. Keadaan
optimum dikenalpasti melalui nilai peratusan tertinggi terhadap kadar sifat
pengembangan yang diperolehi adalah pada tahap komposisi Bentonite sekitar 1.00%,
komposisi agen penyilang sekitar 1.20-1.40% dan cecair rendaman terbaik adalah
dalam air deionisasi. Daya serap air poli(AA-co-AM)/Bentonite dikenalpasti menjadi
3821.57 dan 675.72 g H2Og dalam air deionisasi, larutan alkali dan larutan asid.
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TABLE OF CONTENTS
CHAPTER TITLE PAGES
TITLE PAGE
DECLARATION ii.DEDICATION iii.ACKNOWLEDGEMENT iv.ABSTRACT v.ABSTRAK vi.TABLE OF CONTENT vii.LIST OF TABLES ix.LIST OF FIGURES x.LIST OF ABBREVIATION xi.LIST OF APPENDICES xii.
1 INTRODUCTION
1.1Research of Background1.2Problem Statement1.3Objective1.4Scopes of Study1.5Rationale and Significance
1
3
4
4
6
2 LITERATURE REVIEW
2.1 Inorganic Clay Powder
2.1.1 Bentonite Clay Powder
2.1.2 Composition of Bentonite
7
7
8
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2.2 Application of Superabsorbent Polymer Composites 10
2.3 Superabsorbent Polymer Composites 11
2.4 Solution Polymerization
2.4.1 Solution Polymerization Reaction System
14
14
2.5 Polymer/Clay Superabsorbent Composites 16
3 METHODOLOGY
3.1 Materials and Solvents 18
3.2 Apparatus and Equipment 18
3.3 Research Design 20
3.4 Preparation of Clay Based Superabsorbent Composites 21
3.5 Preparation of Pure Superabsorbent Polymer 22
4 RESULT & DISCUSSION
4.1 Effect of Bentonite content 24
4.2 Effect of crosslinker content 28
4.3 Swelling behavior 32
4.4 Infrared spectra 36
4.5 SEM observations 37
5 CONCLUSION AND RECOMMENDATION 39
REFERENCES 40
APPENDICES 44-48
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LIST OF TABLES
TABLE NO. TITLE PAGE
3.1 Composition of inorganic clay polymer, initiator and
crosslinker used in SPC synthesis
22
4.1 Water absorbency of SPC in distilled water with different
amounts of Bentonite compositions
25
4.2 Water absorbency of SPC in solution pH 13.75 with
different amounts of Bentonite compositions
25
4.3 Water absorbency of SPC in solution pH 2.10 with
different amounts of Bentonite compositions
26
4.4 Water absorbency of SPC in distilled water with different
amounts of MBA compositions
29
4.5 Water absorbency of SPC in solution pH 13.75 with
different amounts of MBA compositions
29
4.6 Water absorbency of SPC in solution pH 2.10 with
different amounts of MBA compositions
30
4.7 Percentages of water absorbency in different types of
physiological fluids with various amount of Bentonite
33
4.8 Percentages of water in different types of physiological
fluids with various amount of MBA
34
4.9 Assignment of FTIR band of Bentonite, poly(AA-co-
AM)/Bentonite and poly(AA-co-AM)
36
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LIST OF FIGURES
FIGURES NO. TITLE PAGE
2.1 Schematic of Montmorillonite structure 8
2.2 Montmorillonite 9
2.3 The application of SPC in various field 10
2.4 A visual comparison of the SPC single particle in dry
and swollen state
12
2.5 Chemical structure of the reactants and general
pathways to prepare an acrylic SPC network
15
2.6 General mechanism for polymerization of acrylamide
and partially neutralized acrylic acid by solution
polymerization
16
4.1 Effect of Bentonite compositions on water
absorbency of SPC in distilled water
26
4.2 Effect of Bentonite compositions on water
absorbency of SPC in solution pH 13.75
27
4.3 Effect of Bentonite compositions on waterabsorbency of SPC in solution pH 2.10
28
4.4 Effect of crosslinker compositions on water
absorbency of SPC in distilled water
30
4.5 Effect of crosslinker compositions on water 31
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absorbency of SPC in solution pH 13.75
4.6 Effect of crosslinker compositions on water
absorbency of SPC in solution pH 2.10
31
4.7 Swelling behavior in different types of physiological
fluids with different amount of Bentonite
compositions
33
4.8 Swelling behavior in different types of physiological
fluids with different amount of MBA compositions
34
4.9 Hydrogel after swelling in distilled water for (a) 30
minutes (b) 5 minutes
35
4.10 Infrared spectra of SPC composites 37
4.11 Scanning electron micrograph of poly(AA-co-AM)
and poly(AA-co-AM)/Bentonite
38
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LIST OF ABBREVIATIONS AND SYMBOLS
FTIR - Fourier Transforms Infrared Spectroscopy
SEM - Scanning Electron Microscopy
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LIST OF APPENDICES
APPENDIX TITLE PAGE
A FTIR characterized: Bentonite analysis 44
B FTIR characterized: Poly(AA-co-AM)/Bentonite analysis 45
C FTIR characterized: Poly(AA-co-AM) analysis 46
D Poly(AA-co-AM) hydrogel 47
E Process of production of poly(AA-co-AM)/Bentonite
powder
48
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CHAPTER 1
INTRODUCTION
1.1Research Background
Superabsorbent polymer composite (SPC) has been defined as polymeric materials
which exhibit the ability of swelling in water and retaining a significant fraction of
water within their structure, without dissolving in water (Zohuriaan and Kabiri,
2008a). SPC are types of loosely crosslinked hydrophilic polymer that can swell,
absorb and retain a large volume of water or other fluid. Desired features of
superabsorbents are high swelling capacity, high swelling rate, and good strength of
the swelling gel. SPC hydrogels relative to their own mass can absorbs and retain
extraordinary large amounts of water or aqueous solution (Zohuriaan and Kabiri,
2008b).
Reviewed by Zohurian and Kabiri (2008c) stated that traditional absorbent
materials (such as tissue papers and polyurethane foams) unlike SPC, will lost most of
their absorbed water when they are squeezed. Table 1.1 compares water absorptiveness
of some common absorbent materials with a typical sample of a commercially
available SPC.
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Table 1.1: Water absorbency of some common absorbent materials in comparison
with a typical commercial SPC sample (Zohuriaan and Kabiri, 2008d)
Absorbent Material Water Absorbency (wt%)Whatman No. 3 filter paper 180
Facial tissue paper 400
Soft polyurethane sponge 1050
Wood pulp fluff 1200
Cotton ball 1890
Superb A-200a 20200
Because of it properties, they widely used in the fields of personal care products,
biomaterials, biosorbents, agriculture and so on (Gohar et al., 2009). For examples
these materials, firstly applied in the United States as water retention agents in
agriculture, were developed in Japan in the mid 1970s in the personal care and
hygienic products disposable diapers, sanitary, napkins, surgical pads, etc. It is well
known that there are many water absorbing materials such as pulp, paper, cotton and
etc which were conventionally used as sanitary towel and diaper. In addition to the
healthcare products, they are used in soil conditioning and as artificial soils for
hydroponics, as controlled release agents for skiing area, and other numerous
applications (Zohuriaan and Kabiri, 2008; Kabiri et al., 2003).
Recently, the applications of hydrogels are grown extensively. Hydrogels that
are responsive to specific molecules, such as glucose or antigens can be used as
biosensors as well as in drug delivery systems (DDS). These kinds of hydrogels are
also used as controlled release delivery devices for boi-active agents and
agrochemicals. Contact lenses are also based on hydrogels (Zohuriaan and Kabiri,
2008e)
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SPC are originally divided into two main classes which are synthesis
(petrochemical-based) and natural. Usually, most of the superabsorbent are frequently
produced from acrylic acid (AA) its salts and acrylamide (AM) via solution or inverse-
suspension polymerization techniques (Zohuriaan and Kabiri, 2008f). Recently, some
researched used inorganic fillers to advance the behaviour of SPC, inorganic fillers
like clay can be used as substitution material (Molu.et al., 2009a; Li and Wang, 2005).
Clays such as kaolin, montmorillonite (MMT), attapulgite, mica, bentonite, and sercite
hydrotalcite have all been used in the preparation of SPC. In this study MMT will be
used as filler. At the end of synthesis, the result will be approved whether advance
SPC composite better than pure SPC.
Several papers have been published to review SPC hydrogel materials, each with
own individual outlook. As a general framework, synthetic methods and properties of
hydrogel networks were reviewed. Synthetic, semi-synthetic and biopolymeric
hydrogels were also briefly reviewed by Zohurian and Kabiri (2008g). Theoretically,
there is a wide range of inorganic materials with expandable layers available for
utilization for the preparation of SPC. In recent years, the study of organic-inorganic
nanocomposites has become a very important field. Currently, reinforcing polymers
with small amounts of smectite clays has attracted increasing interest, because the
derived heterostructural materials exhibit impressive mechanical, thermal, optical, and
other properties that increase their technological values (Suda, 2007a).
Other than using organic clay as the filler on the synthesis of SPC there are other
types of filler or additive use in other research such as used starch, rice husk, organic
fiber and others. For example, SPC obtained from shellfish waste have also been
reviewed by Dutkiewicz (2002). Teli and Nilesh (2010) have reviewed the SPC
materials based on the Amaranthus starch. A review profile of water absorbing resins
based on graft copolymers of acrylic acid and gelatinized starch was presented by
Atawale et al. (2001). Peng et al. (2007) has elaborated the uses of SPC based on graft
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copolymerization blending based on acrylamide (AM), diallydimethylammonium
chloride (DMDAAC) and sodium starch sulfate (SSS) (Peng et al., 2008).
In another review by Zhang et al. (2006), the chitosan-g-poly(acrylic
acid)/attapulgite superabsorbent composite was prepared by graft polymerization with
chitosan, acrylic acid and attapulgite in aqueous solution, using N,N-
methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The
factors influencing water absorbency of the superabsorbent composite were
investigated, such as average molecular weight of chitosan, weight ratio of acrylic acid
to chitosan, dewatering method, the amount of crosslinker and attapulgite have been
discussed in detail (Zhang et al., 2005).
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1.2Problem Statements
Recently Superabsorbent polymers composite (SPC) have been used and applied
but it still have a negative feature in some application fields because of the high
production cost. Thus, study is conducted to overcome this negative point by using,
inorganic filler clay which is Bentonite for developing the properties of superabsorbent
hydrogels. The abundance of bentonite and its low cost are likely to make it a strong
candidate as filler and additive. The resulting product is poly(acrylic acid-co-
acrylamide)/bentonite SPC were synthesized by solution polymerization reaction of
Acrylic acid (AA) and Acrylamide (AM) on bentonite using MDA and APS as
initiator in aqueous solution. It was be used as low cost material and improve the
strength properties in the polymer matrixes, which can be measured by the swelling
behavior.
This study will be conducted to determine the optimum value for amount of
Bentonite, crosslinker and initiator in synthesizing of SPC monomer to obtain the high
value of water absorbency. Thus, the aims of this study to develop the collaborative
absorbent effect through the introduction of Bentonite in reducing the production cost
and improved the swelling capacity of superabsorbent composites.
Review the swelling behavior of SPC in different type of physiological fluid. How
the different conditions of physiological fluid can give effect on the swelling behavior
of the SPC whether it enhance or declining the swelling rate.
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1.3Objectives
This research focused on studied the optimum synthesizing condition of clay based
SPC by determined:
i. Effect on amount of inorganic clay, Bentonite towards water absorbency.ii. Effect on amount of crosslinker towards water absorbency.
iii. Effect on water absorbency to different types of physiological fluids.
Use of expensive monomers/modifiers for increasing water absorbency will result
in increased cost, rendering the resulting SPC economically unsuitable. In order to
develop cheap SPC based on AA and AM in the present study an effort was made to
increase the water absorbency by optimizing the cross-linking parameters, such as
initiator and cross-linker (Singhal et al., 2009a).
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1.4 Scope of Study
The scopes of this research are:
a) Materials
i. Filler that used is Bentoniteii. Type of monomer for SPC were Acrylic acid (AA) and Acrylamide (AM)
iii. Type of crosslinker agent for SPC was N,N-methylenediacrylamide (MDA)iv. Type of initiator for SPC was Ammonium peroxodisulfate (APS)v. Different types of physiological fluid; distilled water, Sodium hydroxide
(NaOH) solution pH 13.75, and Nitric acid (HNO3) solution pH 2.10.
b) Parameters
For sample preparation, three parameters was varied which are amount of
crosslinker, amount of inorganic clay and types of physiological fluids. Analysis will
be analyzed by using Bentonite contents in range 0.0 wt% to 1.4 wt%, for amount of
MDA contents evaluate in range of 0.0 wt% to 1.8 wt% and for types of physiological
fluids was investigated to deionized water, NaOH solution pH 13.75 and HNO3
solution pH 2.10.
c) Apparatus
For making sample three-neck flask was used equipped with a stirrer, condenser,
thermometer, and nitrogen line.
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d) Preparation technique
Polymerization technique was used in this research was solution polymerization.
e) Characterization
The IR spectra of the sample products were characterized by FTIR and the water
absorbency was investigated to different physiological fluids which are deionized
water, NaOH solution pH 13.75 and HNO3 solution pH 2.10.
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1.5Rationale and Significance
The rationales of doing this study were to improve the properties of SPC with
substitution of Bentonite by monitoring parameters, so that collaborative SPC can be
used effectively. According to Li and Wang (2005a) on Synthesis and properties of
clay based superabsorbent composites stated that the water absorbency of the poly
(acrylic acid)/attapulgite superabsorbent composite in distilled water was greatly
improved as compared with crosslinked poly (acrylic acid) superabsorbent polymer, it
proved that collaborative absorbent effect through the information of filler.
To open up opportunities to increase the demand on manufacturing the
collaborative SPC as proven by previous researchers that SPC is useful a lot. In order
to reduce the cost production and improve the efficiency which is high water
absorbency and retention per unit weight of SPC are essential. Because of use
expensive monomers or modifiers for increasing water absorbency will result in
increase cost, rendering the resulting SPC economically unsuitable. In order to develop
cheap SPC based on AA and AM an effort was made to increase the water absorbency
by optimizing the cross-linking parameters, which is addition of filler and cross-linker
(Singhal et al., 2009b).
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CHAPTER 2
LITERATURE REVIEW
2.1 Inorganic Clay powder
2.1.1 Bentonite Clay Powder
Bentonite is a smectite type clay mineral and swells in water. Because of the
swelling property, only small amount of bentonite can be suspended in water. This
may limit certain applications of bentonite.
Clay particle sizes are in the micrometer to nanometer range length scale. The
small dimensions of clay particles suggest a large influence of the molecular scale
behaviour and interactions (particle-particle, particle-water and interlayer) on bulk
mechanical properties. The basic structural units in clays consist of the sheet formed of
silica tetrahedral and the octahedral units formed of octahedrally coordinated cations
(with oxygens or hydroxyls) octahedral as show in Figure 2.1.
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Figure 2.1:Schematic of montmorillonite structure (Katti, 2000)
To advance the behavior of SPC, inorganic fillers can be used to be substitute
material as research before (Molu et al., 2009b; Li and Wang, 2005b). Clays, such as
kaolin, montmorillonite, attapulgite, mica, bentonite and sercite hydrotalcite have all
been used for the preparation of superabsorbent composites.
Bentonite is a naturally occurring material consisting predominantly of the clay
mineral montmorillonite. Montmorillonite is a materials species in the family of sheet
silicates called smectites. Smectites are three layer clays minerals. They consist of two
tetradral layers of interconnected SiO4 tetrahedrons which enclose a central M(O,OH)6
octahedron layer (M=Al, Fe, Mg and others). The silicate layers have a slightly
negative charge that is compensated by exchangeable ions in the intermediate layers.
The charge is so weak that the cations (in natural form, predominantly Ca2+-
, Mg2+-
or
Na
+-
ions) can be adsorbed with an associated hydrate shell (innercrystalline swelling).(European Bentonite Producers Association, 2005)
An essential characteristic of all smectite minerals is their ability to absorb
tremendous amounts of water and other liquids into their sheet structures. This gives
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bentonite extraordinary swelling and adhesive properties that are exploited
commercially by many industries. The ability of smectite to absorb water is due in part
to by the inherently small grain size of individual smectite crystals (typically much less
that 2) and to the fact that individual sheets possess a negative surface charge which
tends to attract polar molecules as show in Figure 2.1. This negative charge is also
responsible for another essential attribute of smectite, its ability to absorb positively
charged ions from solutions, an attribute which, like adhesion, is also exploited
commercially. (Anonymous, 2005)
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2.2 Application of Superabsorbent Polymer Composites
SPC are moderately crosslinked hydrophilic polymer material, which can
imbibe and retain a large amount of aqueous solution. Owning to their excellent
characteristic, SPC have been used in many fields such as healthcare products,
agriculture and horticulture, waste water treatment, medical, and other numerous
applications. Figure 2.3 shows the summary application SPC application in various
fields. (Molu et al., 2009c; Liu and Wang, 2008; Kabiri et al., 2009)
The applicationof
Superabsorbent
in various fields
Healthcare
products
Agriculture and
horticulture eg;holding soil
moisture
Hygienic
eg; disposable
diapers,feminine
napkins.
Waste watertreatment
Gel actuators
Medicine fordrug-delivery
systems
Sealingcomposites
Artificialsnow
Drilling fluid
additives
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Figure 2.3: The application of SPC in various fields (Molu et al., 2009d; Liu and
Wang, 2008a; Kabiri et al., 2009a)
Chemistry and physics of agricultural hydrogels were reviewed by Kazanskii
and Dubrovskii (1992). Singal et al. (2009c) discuss widely about SPC on background,
types, chemical and physical properties, testing method uses and applied research
work.
2.3 Superabsorbent Polymer Composites
SPC hydrogels relative to their own mass can absorbs and retain extraordinary
large amounts of water or aqueous solution. These ultrahigh absorbing materials can
imbibe deionized water as high as 1,000-100,000% (10-1000 g/g) whereas the
absorption capacity of common hydrogels is not more than 100% (1g/g) (Zohuriaan
and Kabiri, 2008h). Structure for SPC hydrogels are given in Figure 2.4. SPC
originally divided into two main classes which is synthetic (e.g., petrochemical based)
and natural (e.g., polysaccharide- and polypeptide-based) (Zohuriaan and Kabiri,
2008i)
They are polymers which are characterized by hydrophilicity containing
carboxylic acid, carboxamide, hydroxyl, amine, imide groups and so on, insoluble in
water, and are cross-linked polyelectrolytes. Because of their ionic nature and
interconnected structure, they absorb large quantities of water and other aqueous
solutions without dissolving by solvation of water molecules via hydrogen bonds,
increasing the entropy of the network to make the Superabsorbent polymer (SAP)
swell tremendously. The factors that supply absorbing power to polymers are osmotic
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pressure, based on movable counter-ions, and affinity between the polymer electrolyte
and water (Suda, 2007b)
Figure 2.4: A visual comparison of the SPC single particle in dry (right) and
swollen state (left) (Zohuriaan and Kabiri, 2008j).
There are many kind of methods to prepare SPC with various starting materials,
such as copolymerizing hydrophilic monomer with a cross-linking agent, grafting
monomer with starch, cellulose, synthetic fiber, and polysaccharide, cross-linking
linear hydrophilic polymer with polyvalent metal ions or organic multifunctional
group materials and others (Thomas et al., 2003a).