STUDY ON CHEMICAL MODIFICATION OF NATURAL AMINOPOLYSACCHARIDE USE AS ABSORBENT TO REMOVE TEXTILE DYES

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MINISTRY OF EDUCATION AND TRAINING
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HANOI UNIVERSITY OF MINING AND GEOLOGY S :
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P
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KIEU NGOC THANH
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STUDY ON CHEMICAL MODIFICATION OF NATURAL
H
AMINOPOLYSACCHARIDE USE AS ABSORBENT TO REMOVE
TEXTILE DYES
3

THESIS

.

HANOI, JUNE 2017


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MINISTRY OF EDUCATION AND TRAINING
HANOI UNIVERSITY OF MINING AND GEOLOGY

KIEU NGOC THANH

THESIS
STUDY ON CHEMICAL MODIFICATION OF NATURAL
AMINOPOLYSACCHARIDE USE AS ABSORBENT TO REMOVE
TEXTILE DYES

SUPERVISOR

REVIEWER

DR. Nguyen Thi Linh

HANOI, JUNE 2017


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Contents


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TABLE CONTENTS
Table 2.1: Effect of ammonium persulfate on crosslinking
Table 2.2: Effect of time reaction on crosslinking
Table 2.3: Effect of temperature on crosslinking
Table 2.4: Effect of APS-AMS dose on absorption
Table 2.5: Effect of dye concentration on absorption
Table 2.6: Effect of agitation time on absorption
Table 2.7: Effect of initial pH on absorption
Table 3.1: Efficiency of samples in changing concentration
Table 3.2: Efficiency of sample in changing reaction time
Table 3.3: Efficiency of samples in changing temperature
Table 3.4: The best condition in chemical modification of
aminopolysaccharide


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FIGURE CONTENTS

Figure 1.1: Commercial Aminopolysaccharide
Figure 1.2: Shell Biorefinery
Figure 1.3: Examples of pigment in the electroplate industry
Figure 2.1: Shell shrimp after demineralization process
Figure 2.2: Experiment progressing
Figure 2.3: Shell shrimp after deacetyl process
Figure 2.4: Aminopolysaccharide dissolved in Acetic acid

Figure 2.5: Procedure of synthesis of aminopolysaccharide from shrimp crusts
Figure 3.1: IR of Aminopolysaccharide
Figure 3.2: Infrared spectroscopy of 4 samples in changing concentration
Figure 3.3: Infrared Spectroscopy of 4 samples in changing time reaction
Figure 3.4: Infrared Spectroscopy of 4 samples in changing temperature
Figure 3.5: UV-VIS of sample in different pH
Figure 3.6: Investigation of pH
Figure 3.7: UV VIS of sample with different time reaction
Figure 3.8: Investigation of time reaction
Figure 3.9: UV-VIS of samples in different concentration
Figure 3.10: Investigation of dye’s concentration
Figure 3.11: UV-VIS of samples in different concentration


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Figure 3.12: Investigation of APS’s concentration

Introduction
Every year, some 6 million to 8 million tonnes of waste crab, shrimp
and lobster shells are produced. The shell waste produced by the seafood
industry is a growing problem, with significant environmental and health
hazards Shrimp processing effluents are very high in biological oxygen
demand, chemical oxygen demand, total suspended solids, fat-oil-grease,
pathogenic and other microflora, organic matters and nutrients.
Shrimp processing effluents are, therefore, highly likely to produce
adverse effects on the receiving coastal and marine environments. Shrimps and
lobsters are among the most popular crustaceans. For instance, specks of flesh
left in the shells serve as an ideal growth media for pathogenic bacteria. This
leads to the need to burn the shells, an environmentally costly activity given
their low burning capacity

Chitin is the major component in the shell of the shrimps, and crabs,
cartilage of the squid, and outer cover of insects. It is also extracted from a
number of other living organisms in the lower plant and animal kingdoms,
serving in many functions where reinforcement and strength are required.
Aminopolysacharide is a natural polysaccharide comprising of copolymers of
glucosamine and N-acetylglucosamine, and can be obtained by the partial
deacetylation of chitin. In its crystalline form, aminopolysaccharide is
normally insoluble in aqueous solutions above pH7; however, in dilute acids
(pH6.0), the protonated free amino groups on glucosamine facilitate solubility
of the molecule.
Aminopolysaccharide has been widely used in vastly diverse fields,
ranging from waste management to food processing, medicine and


8
biotechnology. Especially, Aminopolysaccharide used absorbent to remove
textile dyes.


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CHAPTER 1: OVERVIEW

1.1.

AMINOPOLYSACCHARIDE

1.1.1 Physical properties and structure of aminopolysaccharide
Chitin found in the exoskeleton of crustaceans, the cuticles of insects, and
the cells walls of fungi, is the most abundant aminopolysaccharide in nature

This low-cost material is a linear homopolymer composed of b(1-4)-linked Nacetyl glucosamine. It is structurally similar to cellulose, but it is an
aminopolymer and has acetamide groups at the C-2 positions in place of the
hydroxyl groups. The presence of these groups is highly advantageous,
providing distinctive adsorption functions and conducting modification
reactions. The raw polymer is only commercially extracted from marine
crustaceans primarily because a large amount of waste is available as a byproduct of food processing. Chitin is extracted from crustaceans (shrimps,
crabs, squids) by acid treatment to dissolve the calcium carbonate followed by
alkaline extraction to dissolve the proteins and by a decolorization step to
obtain a colourless product.
More important than chitin is its derivative, aminopolysaccharide.
Aminopolysaccharide is prepared by deacetylating chitin.

Chitin

Aminopolysaccharide


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Figure 1.1: Commercial Aminopolysaccharide

Physical natural of Aminopolysaccharide
Aminopolysaccharide is also crystalline and shows polymorphism
depending on its physical state. Depending on the origin of the polymer
and its treatment during extraction from raw resources, the residual
crystallinity may vary considerably.
Generally, commercial chit- osans are semi-crystalline polymers,
Crystallinity plays an important role in adsorption efficiency.it
demonstrated that decrystallized aminopolysaccharide is much more
effective in the adsorption of anionic dyes. Crystallinity controls polymer

hydratation, which in turn deter- mines the accessibility to internal sites.
This para- meter strongly influences the kinetics of hydratation and
adsorption.
Chemical structure of Aminopolysaccharide
Commercial aminopolysaccharide also varies greatly in its MW and
distribu- tion, and therefore its solution behavior. The MW of
aminopolysaccharide is a key variable in adsorption properties because it
influences the polymer’s solubility and viscosity in solution.

The degree of N-acetylation (DA) or DD. The DD parameter is
essential, though the hydroxyl groups on the polymer may be involved in


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attracting dye molecules, the amine functions remain the main active
groups and so can influence the polymer’s performance.
Aminopolysaccharide is the high hydrophilic character of the
polymer due to the large number of hydroxyl groups present on its
backbone. With an increase in DD, the number of amino groups in the
polymer increases, and with an increase of MW, the polymer
configuration in solution becomes a chain or a ball.
1.1.2 Sources of aminopolysaccharide
The potential value of such shells for the chemical industry is being
ignored. Scientists should work out sustainable ways to refine crustacean
shells, and industry should invest in using this abundant and cheap renewable
Protein is good for animal feeds. For example, Penaeus shrimp shells
contain all the essential amino acids and have a nutrient value comparable to
that of soya-bean meal. Today, the protein is not being used because the current
processing methods destroy it.
Calcium carbonate has extensive applications in the pharmaceutical,

agricultural, construction and paper industries. It currently comes mainly from
geological sources such as marble and limestone. These sources are plentiful
but might contain heavy metals that are difficult to remove.
Chitin is a linear polymer and the second most abundant natural
biopolymer on Earth (after cellulose). It is found in fungi, plankton and the
exoskeletons of insects and crustaceans, and organisms generate about 100
billion tonnes of chitin every year. Currently, the polymer and its water soluble
derivative, amonipolysacharide, are used in only a few niche areas of
industrial chemistry, such as cosmetics, textiles, water treatment and
biomedicine. Its potential is much greater.


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Figure 1.2: Shell Biorefinery
1.1.3 Chemical modification of Aminopolysaccharide.
Crosslinking.
Raw aminopolysaccharide powders also tend to soluble in acidic
media and therefore cannot be used as an insoluble adsorbent under these
conditions. One method to overcome these problems is to transform the
raw polymer into a form whose physical characteristics are more attractive.
So, crosslinked beads have been developed and proposed.
After crosslinking, these materials maintain their properties and
original characteristics, particularly their high adsorption capacity,
although this chemical modification results in a decrease in the density of
free amine groups at the surface of the adsorbent in turn lowering polymer
reactivity towards metal ions.
They also indicated that the crosslinking ratio slightly affected the
equilibrium adsorption capacity for the three cross linkers under the range.

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The amount of dye adsorbed was found to be higher in acidic than in basic
solution.
Grafting reaction
Aminopolysaccharide as such is very useful for treating con- taminated
solutions. It may be advantageous to chemically modify aminopolysaccharides.
The
modifications can improve aminopolysaccharide’s removal
performance and selectivity for dyes, alter the physical and mechanical
properties of the polymer, control its diffusion properties and decrease the
sensitivity of adsorption to environmental conditions.
The ability of aminopolysaccharide to selectively adsorb dyes could
be further improved by chemical derivatization. The presence of new
functional groups on the surface of beads results in increases in surface
polarity and the density of adsorption sites, and this improves the
adsorption selectivity for the target dye.
Aminopolysaccharide Preprotonation
In dilute aqueous acids, the free amino groups are protonated and the
polymer becomes fully soluble below ~pH 5. Since the pKa of the amino
group of glucosamine residues is about 6.3, aminopolysaccharide is
extremely positively charged in acidic medium. So, treatment of
aminopolysaccharide with acid produces protonated amine groups along
the chain and this facilitates electrostatic interaction between polymer
chains and the negatively charged anionic dyes.
In fact, the solubility and its extent depend on the concentration and
on the type of acid. The polymer dissolves in hydrochloric acid and organic
acids such as formic, acetic, lactic and oxalic acids. However, solubility
decreases with increasing concentrations of acid. Solubility is also related
to the DA, the ionic concentration, as well as the conditions of isolation

and drying of the polymer.


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1.1.4 Application of Aminopolysaccharide
Aminopolysaccharide has also been used to remediate organic
contaminants, such as oil-based wastewater, dyes, tannins, humic acids,
phenols, bisphenoi-A, p-benzoquinone, organo-phosphorus insecticides,
among others.
Aminopolysaccharide has also been utilized to develop optical and
electrochemical sensors for in-situ detection of trace contaminants. In sensor
technology, naturally-derived aminopolysaccharide is used primarily as an
immobilizing agent that results from its enzyme compatibility, and stabilizing
effect on nanoparticles. Contaminant-sensing agents, such as enzymes,
microbes and nanoparticles, have been homogeneously immobilized in
aminopolysaccharide gels by using coagulating or crosslinking agents.
They have also been applied in permeable reactive barriers to remediate
metals in soil and groundwater. Both aminopolysaccharide and modified
aminopolysaccharide have been used to phytoremediate metals; however, the
mechanisms by which they assist in mobilizing metals are not yet well
understood. In addition, microbes have been used in combination with
aminopolysaccharide to remediate metals (e.g., Cu and Zn) in contaminated
soils.
1.1.5. Chemical modification of Aminopolysaccharide.
Crosslinking.
Raw aminopolysaccharide powders also tend to soluble in acidic
media and therefore cannot be used as an insoluble adsorbent under these
conditions. One method to overcome these problems is to transform the
raw polymer into a form whose physical characteristics are more attractive.
So, crosslinked beads have been developed and proposed.

After crosslinking, these materials maintain their properties and
original characteristics, particularly their high adsorption capacity,
although this chemical modification results in a decrease in the density of


15
free amine groups at the surface of the adsorbent in turn lowering polymer
reactivity towards metal ions.
They also indicated that the crosslinking ratio slightly affected the
equilibrium adsorption capacity for the three cross linkers under the range.
The amount of dye adsorbed was found to be higher in acidic than in basic
solution.
Grafting reaction
Aminopolysaccharide as such is very useful for treating con- taminated
solutions. It may be advantageous to chemically modify aminopolysaccharides.
The
modifications can improve aminopolysaccharide’s removal
performance and selectivity for dyes, alter the physical and mechanical
properties of the polymer, control its diffusion properties and decrease the
sensitivity of adsorption to environmental conditions.
The ability of aminopolysaccharide to selectively adsorb dyes could
be further improved by chemical derivatization. The presence of new
functional groups on the surface of beads results in increases in surface
polarity and the density of adsorption sites, and this improves the
adsorption selectivity for the target dye.
Aminopolysaccharide Preprotonation
In dilute aqueous acids, the free amino groups are protonated and the
polymer becomes fully soluble below ~pH 5. Since the pKa of the amino
group of glucosamine residues is about 6.3, aminopolysaccharide is
extremely positively charged in acidic medium. So, treatment of

aminopolysaccharide with acid produces protonated amine groups along
the chain and this facilitates electrostatic interaction between polymer
chains and the negatively charged anionic dyes.
n fact, the solubility and its extent depend on the concentration and
on the type of acid. The polymer dissolves in hydrochloric acid and organic


16
acids such as formic, acetic, lactic and oxalic acids. However, solubility
decreases with increasing concentrations of acid. Solubility is also related
to the DA, the ionic concentration, as well as the conditions of isolation
and drying of the polymer.

1.2

Pigments or Dyes
1.2.1 Structure of pigments

A dye or pigments is a coloured compound that can be applied on a
substrate. With few exceptions, all synthetic dyes are aromatic organic
compounds. There are many structural varieties such as acidic, disperse, basic,
azo, diazo, anthraquinone-based and metal complex dyes.
In the field of chemistry, chromophores and auxochromes are the major
component element of dye molecule. Dyes contain an unsaturate group
basically responsible for colour and designated it as chromophore (“chroma”
means colour and “phore” means bearer).

Figure 1.3: Examples of pigment in the electroplate industry

1.2.2 Effect of textile dyes on environment

In the electroplate industry, up to 200,000 tons of these dyes are lost to
effluents every year during the dyeing and finishing operations, due to the


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inefficiency of the dyeing process. Unfortunately, most of these dyes escape
conventional wastewater treatment processes and persist in the environment as
a result of their high stability to light, temperature, water, detergents,
chemicals, soap and other parameters such as bleach and perspiration.
Electroplate wastewaters are characterized by extreme fluctuations in
many parameters such as chemical oxygen demand (COD), biochemical
oxygen demand (BOD), pH, color and salinity. The composition of the
wastewater will depend on the different organic-based compounds, chemicals
and dyes used in the dry and wet-processing steps. Recalcitrant organic,
colored, toxicant, surfactant and chlorinated compounds and salts are the main
pollutants in textile effluents.
The effects caused by other pollutants in electroplate wastewater, and
the presence of very small amounts of dyes (<1 mg/L for some dyes) in the
water, which are nevertheless highly visible, seriously affects the aesthetic
quality and transparency of water bodies such as lakes, rivers and others,
leading to damage to the aquatic environment.
Some dyes are highly toxic and mutagenic, and also decrease light
penetration and photosynthetic activity, causing oxygen deficiency and limiting
downstream beneficial uses such as recreation, drinking water and irrigation.
One of the most difficult tasks confronted by the wastewater treatment plants
of textile industries is the removal of the color of these compounds, mainly
because dyes and pigments are designed to resist biodegradation.
Considering the fact that the textile dyeing process is recognized as one
of the most environmentally unfriendly industrial processes, it is of extreme
importance to understand the critical points of the dyeing process so as to find

alternative, eco-friendly methods.

1.2.3 Some methods to remove dyes
Textile materials can be dyed using batch, continuous or semi-continuous
processes. The kind of process used depends on many characteristics including


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type of material as such fiber, yarn, fabric, fabric construction and garment, as
also the generic type of fiber, size of dye lots and quality requirements in the
dyed fabric. Dyeing is the aqueous application of color to the textile substrates,
mainly using synthetic organic dyes and frequently at elevated temperatures
and pressures in some of the steps.
The strong ability of iron and aluminum as anodes to remove contaminants
may be used. The monomeric and polymeric hydroxyl complexes can remove
contaminants thanks to their high oxidative potentials. In addition, if the iron
and aluminum potential is sufficiently high, other reactions such as direct
oxidation of organic compounds may take place at the anode.
The electrochemical methods are another way in the textile processes. In
general, the electrochemical methods are cleaner than physicochemical and
membrane technologies (the current methods for color removal) because they
use the electron as unique reagent and they do not produce solid residues.
Sodium dithionite (Na2S2O4) is the most used reducing agent in the
industrial dyeing process with this kind of dyes, but after its reaction, it cannot
be recycled. It also produces large amounts of sodium sulfate and toxic sulfite
products. For this reason, the treatment of dyeing effluents requires the
addition of hydrogen peroxide, which also causes high costs and other
additional problems.

1.3

Electroplate wastewater treatment
1.3.1 Biological method

The most economical alternative when compared with other physical
and chemical processes. Biodegradation methods such as fungal
decolorization, microbial degradation, adsorption by (living or dead) microbial
biomass and bioremediation systems are commonly applied to the treatment of
industrial effluents because many microorganisms such as bacteria, yeasts,
algae and fungi are able to accumulate and degrade different pollutants.


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Their application is often restricted because of technical constraints.
Biological treatment requires a large land area and is constrained by sensitivity
toward diurnal variation as well as toxicity of some chemicals, and less
flexibility in design and operation.
Biological treatment is incapable of obtaining satisfactory color
elimination with current conventional biodegradation processes. Moreover,
although many organic molecules are degraded, many others are recalcitrant
due to their complex chemical structure and synthetic organic origin. In
particular, due to their xenobiotic nature, azo dyes are not totally degraded.

1.3.2 Chemical method.
Include coagulation or flocculation combined with flotation and
filtration, precipitation-flocculation with Fe(II)/Ca(OH)2, electroflotation,
electrokinetic coagulation, conventional oxidation methods by oxidizing agents
(ozone), irradiation or electrochemical processes.
These chemical techniques are often expensive, and although the dyes
are removed, accumulation of concentrated sludge creates a disposal problem.

There is also the possibility that a secondary pollution problem will arise
because of excessive chemical use.
Recently, other emerging techniques, known as advanced oxidation
processes, which are based on the generation of very powerful oxidizing agents
such as hydroxyl radicals, have been applied with success for pollutant
degradation. Although these methods are efficient for the treatment of waters
contaminated with pollutants, they are very costly and commercially
unattractive. The high electrical energy demand and the consumption of
chemical reagents are common problems.

1.3.3 Different physical methods
Also widely used, such as membrane-filtration processes (nanofiltration,
reverse osmosis, electrodialysis) and adsorption techniques.


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The major disadvantage of the membrane processes is that they have a
limited lifetime before membrane fouling occurs and the cost of periodic
replacement must thus be included in any analysis of their economic viability.
This process provides an attractive alternative for the treatment of
contaminated waters, especially if the adsorbent is inexpensive and does not
require an additional pre-treatment step before its application. Adsorption is
well known equilibrium separation process and an effective method for water
decontamination applications.
Adsorption has been found to be superior to other techniques for water
re-use in terms of initial cost, flexibility and simplicity of design, ease of
operation and insensitivity to toxic pollutants. Adsorption also does not result
in the formation of harmful substances.

CHAPTER2: EXPERIMENTS

2.1 Materials and Apparatus

•
•
•
•

Shrimp crusts
HCl
NaOH
Acetic Acid


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•
•
•
•
•
•
•
•
•
•

Ammonium persulfate
H2O2
Flasks
Condense
Electric Stove

Filter Paper
pH paper
Thermometer
Stirring machine
Boiler

2.2. Extraction of chitin from shrimp crusts
a, Preliminary treatment
The sample was washed with tap water to remove any insoluble
material on the shell then dried under the sun for 8 hours. The sample was
stored in a closed container prior to use.
b, Demineralization
Get 40grams dried crusts into the cup of 1 litter, pour slowly HCl 10%
and allowed to stand for 12 hours with pH value range 1.0-2.0 at room
temperature. After that the solution was filtered and the sample was washed
with distilled water until neutral pH was achieved (pH=7).
Demineralization is easily achieved because it involves the
decomposition of calcium carbonate into the water soluble calcium salt with
the release of carbon dioxide as shown in the following equation:

1

HCl + CaCO3 → CaCl2 + H2O + CO2 ↑


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Figure 2.1: Shell shrimp after demineralization process
c, Deproteination
A total samples from demineralization were added with NaOH 8% then

left for 12 hours at room temperature with pH ranged from 11-13. After that,
the solution was filtered and the samples were washed with distilled water until
neutral pH was achieved (pH=7). Water from the samples was removed and the
sample is totally white.


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Figure2.2: Experiment progressing
If the sample isn’t white we would use H 2O2 1% to get the completely
white. The sample was washed with distilled water until neutral pH was
achieved. After that dried at 600 C and we have dried white Chitin


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F
igure2.3: Shell shrimp after deacetyl process
d, Deacetylation
10g Chitin add with NaOH 40% and heated at 80 0C. After 6.5h, the
samples were washed with distilled water until neutral pH was achieved
(pH=7). The sample is known as aminopolysaccharide.
This step was executed again and again until the desired product and
higher value DD were achieved. But in reality, we can’t do the same as
experiment because of the high extra expenditure.
5g APS was added with 300ml Acetic Acid 2% and stirring in 30
minutes at room temperature. If the sample dissolved in acetic acid, it would be
properly APS. The residue was grinded to dust and the sample was stored in
closed container prior to use. And the picture after test showed below:

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Figure2.4: Aminopolysaccharide dissolved in Acetic acid

The above steps were described as figure 2.5.

Shrimp shell

Demineralization