Study on the removal of color from aqueous solution using tio2 chitosan beads anh films

THÀNH PHỐ HỒ CHÍ MINHSTUDY ON THE REMOVAL OF COLOR FROM AQUEOUS SOLUTION USING TIO2 – CHITOSAN BEADS AND FILMS GVHD:Hoang Thi Tuyet Nhung SVTH:Dao Thanh Long MSSV: 15150018 Nguyen Hoan

THÀNH PHỐ HỒ CHÍ MINH

STUDY ON THE REMOVAL OF COLOR FROM AQUEOUS SOLUTION USING TIO2 – CHITOSAN

BEADS AND FILMS

GVHD:Hoang Thi Tuyet Nhung SVTH:Dao Thanh Long MSSV: 15150018 Nguyen Hoang Thuy Tien MSSV:15150038

ĐỒ ÁN TỐT NGHIỆP NGÀNH ENVIROMENTAL TECHNOLOGY

SKL 0 0 6 0 7 9

GRADUATION THESIS

HCMC, July 2019

STUDY ON THE REMOVAL OF

COLOR FROM AQUEOUS

BEADS AND FILMS

Dao Thanh Long 1515001

SUPERVISOR: Dr Hoang Thi Tuyet Nhung

Nguyen Hoang Thuy Tien 15150038

COURSE: 2018 – 2019

HCMC UNIVERSITY OF TECHNOLOGY AND EDUCATION

FALCUTY FOR HIGH QUALITY TRAINING – ENVIROMENTAL TECHNOLOGY

***

SOCIALIST REPUBLUC OF VIETNAM Independence – Freedom – Happiness

***

MISSION OF GRADUATION THESIS

Major: Environmental Engineering and Technology Class: 15150CL2

Supervisor: Dr Hoang Thi Tuyet Nhung

1 Topic: Study on the removal of color from aqueous solution using TiO2 – chitosan

beads and films

Fields: Research

2 Content implementation

- Prepare bead and film forms from chitosan, glycerol and TiO2

- Observe the catalytic activity of samples with different kind of organic colors such

as Methyl Orange, Near Wash Yellow, Acid Blue and Textile Color

- Examine the characteristics of the prepared material by the SEM, EDX, FTIR, XRD methods

- Evaluate the effect of factors on the color reduction such as pH, hydraulic retention time, the concentration of TiO2, mass of material and initial color concentration

Ho Chi Minh, 29 / 7 / 2019

SUPERVISOR

Hoang Thi Tuyet Nhung

SOCIALIST REPUBLUC OF VIETNAM Independence – Freedom – Happiness

***

COMMENT OF SUPERVISOR Name: Dao Thanh Long Student ID: 15150018 Nguyen Hoang Thuy Tien 15150038

Major: Environmental Engineering and Technology Topic: Study on the removal of color from aqueous solution using TiO2 – chitosan beads and films Supervisor: Dr Hoang Thi Tuyet Nhung COMMENT 1 Content impletemation & amount of work:

2 Advantage:

3 Disadvantage:

4 Defense: Yes/No

5 Evaluate of find:

6 Score:

Ho Chi Minh, / / 2019

SUPERVISOR

Hoang Thi Tuyet Nhung

SOCIALIST REPUBLUC OF VIETNAM Independence – Freedom – Happiness

***

COMMENT OF REVIEWER Name: Dao Thanh Long Student ID: 15150018 Nguyen Hoang Thuy Tien 15150038

Major: Environmental Engineering and Technology Topic: Study on the removal of color from aqueous solution using TiO2 – chitosan beads and films Reviewer: Assoc Prof Nguyen Van Suc COMMENT 1 Content impletemation & amount of work:

2 Advantage:

3 Disadvantage:

4 Defense: Yes/No

5 Evaluate of find:

6 Score:

Ho Chi Minh, / / 2019

REVIEWER

Assoc Prof Nguyen Van Suc

ACKNOWLEDGEMENT

We sincere and special gratitude goes to my supervisor Dr Hoang Thi Tuyet Nhung for her unreserved assistance towards the completion of this work We express our thanks to Dr Nguyen My Linh – Head of environment technology department, for her unrelenting support and help

We also say thank for the encouragement, guidance from the teachers and staff of FHQ, FCFT and from the seniors and our friends We would also like to thank to all environmental technologically teachers who have taught and helped us in four years of college Last but not least, We express our gratitude to our parents for their support and encouragement throughout our study

Ho Chi Minh, 29 / 7 / 2019

Nguyen Hoang Thuy Tien Dao Thanh Long

ABSTRACT

The "Efficiencies of color removal using TiO2 – chitosan beads and films" project aims to create a low- cost and new eco-friendly material to remove colors in aqueous solution In this study, methyl orange, near wash yellow, acid blue and textile color specifically used

There are eight different kinds of materials were prepared: bare chitosan (C0) bead/film, Chitosan –TiO2 (CTi) bead/film, Chitosan – Gly (CG) bead/film, Chitosan – Gly – TiO2 (CGTi) bead/film The materials were analyzed of chemical composition, structure, surface area of materials by modern physico-chemical analysis methods such

as X-ray powder diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy analysis (EDX) and Fourier transform infrared spectroscopy (FTIR) analysis

C0 bead, CG beads have the same low ability to remove colors and COD, only12 – 15% due to the adsorption capability of Chitosan The decoloration efficiency of CTi beads are about 30 – 35% The highest decoloration efficiencie is of CGTi beads which are from70 to 75% The optimal kind of material in bead form, HRT,mass and pH are CGTi10, 90 minutes, 2 g, pH = 5 with AB and NWYand pH = 6 with MO, respectively

The results show that CTi film has fewer treatment efficiencies than CGTi10 film and higher treatment efficiencies than C0 and CG The treatment efficiencies of CGTi film is slightly higher compared with that of CGTi bead, due to the dispersion of TiO2

on the surface of the CGTi material which helps the photocatalytic catalytic process perform better The optimal kind of material in film form, HRT and pH are CGTi15, 30 minutes, pH = 3 and 5, respectively

Keywords: Glycerol, Chitosan, Tripolyphosphate, Crosslink, Decoloration, TiO2, …

We would like to take the honor and prestige of ourselves to ensure this assurance

Ho Chi Minh, 29 / 7 / 2019

Nguyen Hoang Thuy Tien Dao Thanh Long

TABLE OF CONTENS

LIST OF TABLES i

LIST OF FIGURES ii

LIST OF ACRONYMS iv

INTRODUCTION 1

1 The purpose and urgency of the study 2

2 Contents of the study 3

3 Scope, object and methods of the study 3

3.1 Scope of the study 3

3.2 Object of the study 4

3.3 Methods of the study 4

4 Practical meaning 4

CONTENT 5

Chapter 1: RESEARCH OVERVIEW 6

1.1 Research overview 6

1.2 Research overview in Vietnam 7

Chapter 2: THEORETICAL OVERVIEW 9

2.1 OVERVIEW OF DYE 9

2.1.1 Concept 9

2.1.2 Classification of dyes 9

2.1.3 Type of dyes used for research 10

2.2 OVERVIEW OF CHITOSAN 12

2.2.1 General introduction 12

2.2.2 History of formation and development 12

2.2.3 Chemical properties of Chitosan 13

2.2.4 Physical properties of Chitosan 13

2.2.5 Physical properties of Chitosan 14

2.2.6 Chitosan preparation process 18

2.2.7 Overview of researched Chitosan 19

2.3 OVERVIEW OF TiO2 19

2.3.1 Formations and crystal structures of TiO 2 19

2.3.2 Properties of TiO 2 21

2.3.3 Factors affecting photochemical catalytic process of TiO 2 23

2.3.4 Some limitations of TiO 2 25

2.3.6 Overview of research TiO 2 (Degussa, P-25) 27

2.4 OVERVIEW OF GLYCEROL 27

2.4.1 Food industry applications 27

2.4.2 Medical, pharmaceutical and personal care applications 27

2.5 OVERVIEW OF SODIUM TRIPOLYPHOSPHATE (STPP) 28

2.6 OVERVIEW OF TAGUCHI METHOD (MINITAB SOFTWARE) 30

Chapter 3: METHODOLOGY 33

3.1 EQUIPMENT, TOOLS AND CHEMICALS 33

3.1.1 Equipment 33

3.1.2 Tools 33

3.1.3 Chemicals 33

3.2 SYNTHESIS OF CGTI 34

3.2.1 Chemicals 34

3.2.2 Process of material preparation 34

3.2.3 Determination of materials physical properties 36

3.2.4 Material symbols 37

3.3 MATERIAL ANALYSIS METHODS 38

3.3.1 X-Ray Powder Diffraction analysis (XRD) 38

3.3.2 Fourier transform infrared spectroscopy analysis (FTIR) 38

3.3.3 Scanning electron microscope analysis (SEM) 38

3.3.4 Energy-dispersive X-ray spectroscopy analysis (EDX) 38

3.4 EXPERIMENTS 39

3.4.1 Creating standard curve 39

3.4.2 Decoloration efficiencies of bead materials 42

3.4.3 Decoloration efficiencies of CGTi films 46

3.4.4 Comparation of color removal between Chitosan - TiO 2 beads and films 47

Chapter 4: RESULTS AND DISCUSSION 48

4.1 CHARACTERISTICS OF MATERIALS 48

4.1.1 Physical properties of the material 48

4.1.2 Structure of material samples 49

4.1.3 FT-IR spectrum 50

4.1.4 Morphology of surface material 52

4.2 DECOLORATION EFFICIENCIES OF CGTi BEADS 54

4.2.1 Comparation of decoloration abilities among materials 54

4.2.2 Effect of the factors in the photocatalysis process 57

4.2.3 Experiment with UVA reactor 59

4.3 DECOLORATION EFFICIENCIES OF CGTi FILMS 64

4.3.1 Comparation of decoloration abilities among materials 64

4.3.2 Effect of the factors in the photocatalysis process 66

4.4 COMPARING TREATMENT ABILITIES BETWEEN CGTi BEAD AND FILM 67

CONCLUSION 68

1 Conclusion 69

2 Recommendation 69

REFERENCES v

APPENDICES viii

LIST OF TABLES

Table 2.1 Different types of dyes apply to different fabrics 10

Table 2.2 Some structural properties of the shape of TiO2 20

Table 3.1 Material symbols 37

Table 3.2 Results of optimal wavelength survey of Methyl orange, Near wash Yellow, Acid Blue and Textile Color 39

Table 3.3 Variable optical density of solution MO standard curve 39

Table 3.4 Variable optical density of solution NWY standard curve 40

Table 3.5 Variable optical density of solution AB standard curve 40

Table 3.6 Variable optical density of solution color degree standard curve 41

Table 3.7 Summation of standard curve 42

Table 3.8 Control factors and their levels used for the design of sunlight experiments with CGTi bead 43

Table 3.9 Sunlight experiment with CGTi bead 43

Table 3.10 Experimental model parameters 45

Table 3.11 Control factors and their levels used for the design of sunlight experiments with CGTi film 46

Table 3.12 Sunlight experiment with CGTi film 47

Table 4.1 The content of elements of the sample C0 52

Table 4.2 The content of elements of the sample CGTi10 bead 53

Table 4.3 Optimal values of CGTi bead and CGTi film 67

LIST OF FIGURES

Fig 2.1 Chemical Structure Depiction of methyl orange 11

Fig 2.2 Chemical Structure Depiction of NWY 11

Fig 2.3 Chemical Structure Depiction of acid blue 12

Fig 2.4 Process of preparing chitosan 19

Fig 2.5 Crystal structures of TiO2 20

Fig 2.6 Crystal structures of TiO2 21

Fig 2.7 Schematic diagram of TiO2 photocatalyst mechanism 22

Fig 2.8 Band-gap energy of some photochemical catalysts 25

Fig 2.9 Chitosan-TPP Gel Bead Formation in the Absence of Porogen 29

Fig 2.10 Chitosan-TPP Gel Bead Formation in the Presence of Porogen 29

Fig 2.11 Chitosan-TPP Gel Bead after Removal of the Porogen 30

Fig 3.1 Gel solution preparation 34

Fig 3.2 Create CGTi bead 35

Fig 3.3 Create CGTi film 35

Fig 3.4 MO standard curve 39

Fig 3.5 NWY standard curve 40

Fig 3.6 AB standard curve 41

Fig 3.7 Color standard curve 41

Fig 3.8 Experiments model for CGTi bead under sunlight 42

Fig 3.9 Experiments model for CGTi bead with UVA light reactor 44

Fig 3.10 Experiments model for CGTi film under sunlight 46

Fig 4.1 Bead before dry 48

Fig 4.2 Bead after dry 48

Fig 4.3 CGTi film 48

Fig 4.5 XRD of CGTi10 bead before and after treatment 50

Fig 4.6 FTIR of CGTi and Chitosan bead samples 51

Fig 4.7 Morphology of surface material (a) C0, (b) CGTi10 52

Fig 4.8 Spectrum EDX sample Chitosan bead 53

Fig 4.9 Spectrum EDX sample CGTi10 bead 53

Fig 4.10 Decoloration efficiencies of C0, CG, CTi, CGTi10 beads for AB 54

Fig 4.11 COD removal efficiencies of C0, CG, CTi, CGTi10 beads for AB 55

Fig 4.12 Decoloration efficiencies of C0, CG, CTi, CGTi10 beads for TC 56

Fig 4.13 COD removal efficiencies of C0, CG, CTi, CGTi10 beads for TC 56

Fig 4.14 Factors affect the photochemical catalytic process of CGTi bead 57

Fig 4.15 Decoloration efficiencies of CGTi beads under UVA light for AB 59

Fig 4.16 Decoloration efficiencies of CGTi beads under UVA light for NWY 60

Fig 4.17 The result of AB (a) and NWY (b) under UVA light in flow experiment 61

Fig 4.18 Treatment efficiencies of Textile Color (a) and COD removal (b) 62

Fig 4.19 Color and COD removal efficiencies under sunlight and in dark for MO 62

Fig 4.20 Color and COD removal efficiencies under sunlight and in dark for NWY 63

Fig 4.21 Color and COD removal efficiencies under sunlight and in dark for AB 63

Fig 4.22 Decoloration efficiencies of C0, CG, CTi, CGTi15 films for AB 64

Fig 4.23 COD removal efficiencies of C0, CG, CTi, CGTi15 films for AB 64

Fig 4.24 Decoloration efficiencies of C0, CG, CTi, CGTi15 films for TC 65

Fig 4.25 COD removal efficiencies of C0, CG, CTi, CGTi15 films for TC 65

Fig 4.26 Factors affect photochemical catalytic processes of CGTi film 66

Fig 4.27 Decoloration efficiencies of CGTi bead and CGTi film (a) COD removal (b) 67

LIST OF ACRONYMS

DA Degree of acetylication

EDX Energy Dispersive X-Ray Analysis

FDA Food and Drug Administration

FT-IR Fourier Transform Infrared Spectroscopy

P25 TiO2 (particle size 25 nm), Degussa

INTRODUCTION

1 The purpose and urgency of the study

Nowadays, the textile and dyeing industry is one of the industries that have steady development steps This industry not only creates diversified products with high quality but also satisfies the increasing demand of the market On the other hand, it also takes places an essential position for contributing to solve jobs for society and promote the growth of export turnover for the country However, the fact shows that the textile and dyeing industry is also the cause of environmental pollution now through the discharge wastewater to the environment; especially in developing countries like Vietnam Therefore, the critical task is to have a strict solution for treating textile wastewater although the textile industry is continuously innovating in technology in order to limit the use amount of water as well as minimize the impact to the environment (MOIT, 2010) The wastewater of the textile industry contains many different kinds of pollutants; the colorants have been shown as the main cause of water pollution in many previous researches Most of the colorants contain noxious organic compounds and non-biodegradable which remain for a long time or only partially decompose into mutants for aquatic organisms after going into the environment and cause cancer to humans and animals (Phong, 2006) Thus, rejecting the pigments from textile wastewater has been a matter of great interest

There are a variety of materials in previous studies which can remove the pigments

in textile wastewater, among of those, the method of colorants processing by photochemical catalysts is used popularly and achieved a high efficiency; especially the semiconductor Titanium Dioxide (TiO2) Currently, small size TiO2 crystal in rutile, anatase, or rutile, anatase, brookite mixtures have been researched and applied in scientific fields such as solar battery, photochemical water-decomposing, making photocatalyst materials to synthesize organic compounds, dealing with the environment, manufacturing self-cleaning paints, manufacturing electronic devices, sensor heads and

in the field of bactericidal (Mike, 2004; Wang and et.al., 2002) New applications of TiO2 nanometer materials are based primarily on its stable redox With high photocatalytic activity, fast surface and non-toxic structure, TiO2 materials are one of the best materials to solve many serious problems and challenges from environmental

challenging to retain in the material Hence, it needs a substrate to keep TiO2 in the material for long-term using

In recent years, along with finding new applications of chitin, chitosan and derivatives, producing and consumption of chitin and chitosan products are being continued growth Because of this, it helps to reduce the pollution of the environment from the food industry such as the solid waste from shrimp and crab shells, cuttlefish can be made use of producing chitosan, this process is also very feasible in the economic aspect it take advantage of protein and carotenoids Besides, chitosan can also be used

as an absorbent material to remove the heavy metals and organic pollutants such as dye with the presence of amino and hydroxyl functional groups in its molecular circuit When combing with TiO2, chitosan acts as a solid substrate to hold TiO2 inside the material and together with it in order to treat pollutants more thoroughly

The topic “Study on the removal of color from aqueous solution using TiO 2 – chitosan beads and films " is carried out with the desire to be able to pursuit for a new

friendly materials with the environment with highthe treatable measures, apply to practice and contribute to solve the present polluted circumtance of the environment in near future

2 Contents of the study

- Prepare bead and film forms from chitosan, glycerol and TiO2

- Observe catalytic activity of samples with different kinds of organic color such as Methyl Orange, Near Wash Yellow, Acid Blue and Textile Color

- Examine the characteristics of the prepared material by SEM, EDX, FTIR, XRD methods

- Evaluate the effect of factors on the color reduction such as pH, hydraulic retention time, the concentration of TiO2, mass of material and initial color concentration

- Compare the effect of color reduction between beads and films forms

3 Scope, object and methods of the study

3.1 Scope of the study

Overview of the photochemical process

Overview of materials (Chitosan, TiO2, Glycerol )

Overview of colorants (Acid Blue, Near wash yellow, methyl orange)

Overview of experimental planning theories (Minitab software, Taguchi)

3.2 Object of the study

Acid Blue, Wash Yellow, Metyl Orange dyes

TiO2 material - chitosan beads

TiO2 material – chitosan films

3.3 Methods of the study

Experimental method: this is an essential step in the research process, manipulations

in experiments must be done carefully, logical, detailed, meticulous in bringing research results with the least errors

Comparison method: used to compare the research results to find the best result

Methods of data processing: Microsoft Word and Microsoft Excel

Methods of analysis and evaluation: analysis of chemical composition, structure, surface area of materials by modern physico-chemical analysis methods such as FTIR, XRD, SEM, EDX,

Graph method: use graphs to perform data easy way, more accurate discussion …

Taguchi method (Minitab software): use as a statistical method to reduce the number

of the experiment, time, and experimental cost

CONTENT

Chapter 1: RESEARCH OVERVIEW 1.1 Research overview

Titanium dioxide (TiO2) is well - known to represent photocatalysts that effectively decompose organic contaminants for water purification, air cleaning, water separation

to create H2, O2, self-cleaning surfaces, antibacterial due to intense oxidizing activity and hydrophilic (Krishna and et.al., 2013)

The widespread application of TiO2 faces difficulties in wastewater treatment because most TiO2 washes away after treatment Therefore, TiO2 materials are converted into hybrid materials such as doped, composite, cross-link to keep TiO2

from being lost after treatment (Anderson and et.al., 1997; Cris and et.al., 2008; Yang and et.al., 2014) In 2014, E I Nkechinyere had a study on Preparation And Characterization Of Porous Chitosan Tripolyphosphate Gel Bead Chitosan films, beads are not stable in acidic media and this necessitates modification which is either physical

or chemical, the commonest being crosslinking Low or high molecular weight compounds which include ionic compounds are used as crosslinking agents Ionic crosslinking is one of the simple methods and it occurs under mild conditions Low molecular weight sodium tripolyphosphate (TPP) was used as a crosslinking agent (Nkechinyere, 2014)

At the same time, they are studying the types and shapes of different photocatalytic materials of TiO2 (bead, film, clinging to other material surfaces) (Mufti and et.al., 2017; Tian and et.al., 2012; Xi and et.al., 2012) In 2013, P Norranattrakul, K Siralertmukul and R Nuisin had a study in Fabrication Of Chitosan / Titanium Dioxide Composites Film For The Photocatalytic Degradation Of Dye Incorporation of TiO2 nanoparticle into chitosan film via solution casting method produced the chitosan-TiO2 film The immobilized TiO2 exhibited proper distribution in chitosan film when the small amount

of TiO2 was added The chitosan-TiO2 film will be promising sources for photocatalyst materials for various organic compounds in the environment The thin film catalyst can

be easily recycled and suspended in the aqueous solution in order to increase the degree

of pollutants removal with TiO2 (Norranattrakul and et.al., 2013)

In 2001, Alessandra B.P and et.al had a study on Photocatalytic Degradation of Acid Blue 80 in Aqueous Solutions Containing TiO2 Suspensions The photocatalytic degradation of the anthraquinonic dye Acid Blue 80 in aqueous solutions containing TiO2 dispersions has been investigated Although a relatively fast decolorization of the solutions has been observed (about 72%), the mineralization is slower (from 4h to 5h), and the presence of residual organic compounds was evidenced even after long term irradiation, confirming the relevant stability of anthraquinone derivatives (about 85% after 4h) (Alessandra and et.al., 2001)

In 2009, Zhang Y., Wan J and Ke Y had a study in A novel approach of preparing TiO2 films at low temperature and its application in photocatalytic degradation of methyl orange The photocatalytic activity of the non-calcinated TiO2 film was evaluated by degradation rate of methyl orange (MO) The results showed that the degradation rate

of MO increased with the amount of TiO2, and it was higher in both acidic (about 95.5%) and alkaline (93.3%) media than under neural (75.2%) condition In addition, lower pH was more favorable for the degradation of MO The photocatalytic degradation of MO could be described as first order reactions When the initial concentration of MO increased from 1 mg/L to 10 mg/L, the highest degradation rate was achieved at 5 mg/L (Zhang and et.al., 2009)

In 2014, Li D and et.al had a study in A novel double-cylindrical-shell photoreactor immobilized with monolayer TiO2-coated silica gel beads for photocatalytic degradation

of Rhodamine B and Methyl Orange in aqueous solution Photocatalytic degradation of RhB and MO using the developed photocatalytic reactor was confirmed by UV–VIS–NIR spectroscopy analysis and kinetic studies The operational parameters including flow rate, initial concentration and repetitive operation for the degradation of RhB and

MO was investigated to optimize the developed photocatalytic reactor The developed photocatalytic reactor, in comparison with reported slurry-suspension and thin film photoreactors, showed higher efficiency and better repetitive operation performance for the degradation of RhB and MO (from 49.6% to 90.6%) (Li and et.al., 2014)

1.2 Research overview in Vietnam

In 2011, Nguyen Xuan Van had a study on preparing TiO2 thin film for photocatalytic application The research on manufacturing thin films of TiO2 anatase

doped N nanoparticles by annealing high temperature method (500oC) to produce TiO2

film to absorb the visible light application in photocatalyst (Van, 2011)

In 2016, Le Tien Khoa and at.al had a Study of photocatalytic activity of TiO2

fluorinated by thermal shock method for the degradation of different dyes The photocatalytic activity of catalysts was evaluated via the degradation of methylene blue (cationic dye) and methyl orange (anionic dye) The results showed that the thermal shock fluorination and the rise of solution pH can increase the surface negative charge

of TiO2, which enhanced the adsorption of methylene blue (from 18.85% to 27.97 %) and then improved the photocatalytic degradation of this cationic dye under UV and visible light On the other hand, after the fluorination, the adsorption of methyl orange

on TiO2 was strongly reduced (from 4.29% to 0.43%), which limited the photocatalytic oxidation of this anion dye (Khoa and et.al., 2016)

However, the combination of using other materials such as chitosan, glycerol, with TiO2 in films and beads form to implement photocatalyst process is very rare From the above analysis, the goal of this thesis is that: Researching the efficiencies of color removal by using TiO2 - chitosan films and beads under sunlight and UVA lamp

Chapter 2: THEORETICAL OVERVIEW2.1 OVERVIEW OF DYE

2.1.1 Concept

A dye is a colored substance that chemically bonds to the substrate to which it is being applied, this distinguishes dyes from pigments which do not chemically bind to the material they color The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber

2.1.2 Classification of dyes

Colorings used in the textile industry can first be divided into dyes (soluble substances) and pigments (insoluble substances) Secondly, colorings can be organized according to their application technologies - reactive dyes, disperse dyes, reconstituted dyes, color-dye dyes, acid / base dyes, direct dyes, metal complex dyes and pigments Finally, dyes can be classified according to their chemical composition (azo, anthraquinone, sulfur, triphenylmethane, indigoid, phthalocyanine, etc.) or in the way they operate in the dyeing process

Most of the coloring agents used in the textile industry are soluble dyes The most obvious in these substances is azo dyes (70-80%) Most pigments on the market are azo pigments, followed by phthalocyanine

Nearly all of the dyes described in this manual are currently being used in the textile industry and cannot easily be replaced, because each dye has its specific benefits It is compared to other dyes For example, when dyeing cellulose, direct and reactive dyestuffs are often used Active dyes create bright colors and its performance is excellent

However, direct dyes are sometimes used to dye cellulose (although its color fastness is much lower than that of reactive dyes), because direct dyes used in this easiest process have low cost (Tuyen, 2012)

Different types of dyes apply to different fabrics

Table 2.1 Different types of dyes apply to different fabrics

Usually produced in the form of powder, orange, unspecified melting temperature

at more than 300oC, at high temperatures decompose, soluble in hot water

Metyl orange has a high purity and able to change color when the pH of the medium changes at a fixed point so it is used as a titrant Because the methyl orange color range

is at the pH range of the average acid, it is often used in acid titration Unlike conventional indicators, methyl orange does not have a defined discoloration band but has the correct end point of the discoloration process

In the weak acidic solution, methyl orange gradually changes from red red (pH below 3.1) to orange and yellow (pH above 4.4) and vice versa Metyl orange in water has pKa = 3.47 at 25oC

In xylene cyanol solution, methyl orange changes from gray gray to violet (pH below 3.2) and then green (pH above 4.2)

Fig 2.1 Chemical Structure Depiction of methyl orange

2.1.3.2 Near wash yellow RCL

RCL yellow near wash is the dye chemical with the molecular formula

C24H19CLFN9Na2O9S2 in the form of yellow powder, odorless, soluble in water (100g /

l at 30oC conditions), specific gravity 0.5 - 0.6 g / cm3

Fig 2.2 Chemical Structure Depiction of NWY

2.1.3.3 Axit blue

Acid blue (C20H13N2NaO5S) is violet blue powder Soluble in water, soluble in ethanol Used to dye and print wool, silk, nylon and wool blended fabrics It can also be used as a food dye and organic pigment, as well as in the field of paper color and hygiene

Fig 2.3 Chemical Structure Depiction of acid blue

2.2.1 General introduction

Chitosan and chitin are polysacharids with many important applications in industry, agriculture, medicine and environmental protection such as: production of glucosamine, surgical sutures, creams, fabrics, paints, and flower protection agents fruits, environmental protection Chitin and chitosan are produced from crustaceans such as shrimp, crab

In Vietnam, crustaceans are an abundant source of raw materials, accounting for one third of the total production of seafood materials In the export seafood processing industry, the proportion of frozen crustacean items accounts for 70 – 80 % of processing capacity Annually, processing plants have disposed a large amount of crustacean waste

of about 70,000 tons / year The production of chitosan is derived from shrimp shells, bringing high economic efficiency and contributing to solving a large amount of waste

in the food industry

Because of the wide applicability of chitin-chitosan, many countries in the world including Vietnam have researched and produced this product (Khoa, 2010)

2.2.2 History of formation and development

Chitin compound first discovered in a fossil insects from 24.5 million years ago The study of the first chitin in 1811 was conducted by a French professor H Braconnot,

he separated chitin from a fungus and called a fungine (Roberts, 1992)

Subsequent studies began in 1823, A Odier isolated from turpentine in a beetle that

he considered chitin (Roberts, 1992) In 1884, J.G Children publishes a publication that includes research by Odier and his own Accordingly, he demonstrated the existence of nitrogen in chitin (Roberts, 1992)

In 1884, studies showed that chitin could be obtained by heating shrimp and crab shells, spider mollusks in KOH solution at 180 oC, dissolving this product in acetic acid and then alkaline it to obtain a substance called chitosan The studies were still conducted and in 1939, E Fisher and H Leeuchs used the synthetic substance of D-glucosamine to find chitosan lattice

2.2.3 Chemical properties of Chitosan

In the chitin / chitosan molecule containing the functional groups -OH, - NHCOCH3

in the N-acetyl-D-glucozamine chains and the –OH group, the -NH2 group in the glucozamine links means they are both alcoholic and Amine, both amide Chemical reactions can occur at the position of the functional group that produces the lead potential O-, derivative N-, or lead potential O-, N-

D-On the other hand, chitin / chitosan are the polymers that monomers are connected

by β- (1-4) -glicozite bonds; These bonds are easily cut off by chemical substances such

as acids, bases, oxidizing agents and hydrolysis enzymes (Hung, 2005)

2.2.4 Physical properties of Chitosan

Chitin and chitosan are biologically large polymer molecules

Chitin has natural morphology in solid form The color of the crustaceans forms from the compounds of chitin (4-ketone derivatives and 4.4 'di xeton-ß-carotene) Chitosan is an amorphous, porous, light, flake-shaped solid that can be ground into different sizes

Soluble Chitosan Ordimethylactamine (DMA) contains 8% lithium choloride or organic acid such as acetic acid, citric acid, chlohydrite acid, insoluble in water, caustic soda, alcohol or other organic solvents

Chitosan powder is slightly viscous in nature and its color varies from light yellow

to white

Like cellulose, chitosan is a fiber, but unlike plant fiber, chitosan has the ability to make films, has the properties of optical structures

Chitosan has the ability to positively charge so it has the ability to combine with negatively charged substances such as fat, lipid and bile acid

Chitosan is a high viscosity substance The viscosity of chitosan depends on many factors such as deacetylation level, atomic mass, solution concentration, strength of ionic force, pH and temperature

The density of chitin from shrimp and crabs is usually 0.06 and 0.17 g/ml, which suggests that shrimp chitin is spongy from crabs, from mollusks stiffer from crabs 2.6 times The density of chitin and chitosan from crustaceans is very high (0.39g/cm3), it depends on the processing method, in addition, the level of deacetylation also increases their density (Hung, 2005)

2.2.5 Physical properties of Chitosan

Chitin and chitosan are biologically large polymer molecules

Chitin has natural morphology in solid form The color of the crustaceans forms from the compounds of chitin (4-ketone derivatives and 4.4 'di xeton-ß-carotene) Chitosan is an amorphous, porous, light, flake-shaped solid that can be ground into different sizes

Soluble Chitosan Ordimethylactamine (DMA) contains 8% lithium choloride or organic acid such as acetic acid, citric acid, chlohydrite acid, insoluble in water, caustic soda, alcohol or other organic solvents

Chitosan powder is slightly viscous in nature and its color varies from light yellow

The density of chitin from shrimp and crabs is usually 0.06 and 0.17 g/ml, which

times The density of chitin and chitosan from crustaceans is very high (0.39 g/cm3), it depends on the processing method, in addition, the level of deacetylation also increases their density (Hung, 2005)

➢ Moledule weight – MW

Because chitosan is a polymer made up of a chain of D-glucosamine (sugar) groups, the total length of the molecule is extremely important Therefore, molecular mass is an important characteristic in the application of chitosan Molecular mass of chitin in nature

is very high, millions of Daltons

However, the chemical reaction that prepared chitosan tends to break down, so the molecular weight of chitosan is only about 100 kDa to 1200 kDa If the reduction of acetylic reaction takes place in an inert medium, it is possible to retain the molecular chain On the other hand, low molecular weight may be due to enzymatic processes or other chemical methods

The smaller the molecular mass, the more soluble chitosan is in water without acid This is a utility for the use of Chitosan in cosmetic and pharmaceutical technology when

pH fluctuates around 7.0

Molecular mass depends on the source of raw materials and pre-preparation of chitin Chitosan is affected by reduction processes such as the depolarization of free radicals, the hydrolysis process has the catalyst of alkali, acid or enzymes The mass of chitosan is also affected by protein reduction in chitin extract

The molecular mass can be measured by means of a device that determines penetration, disperses light, or measures viscosity In particular, the method of measuring viscosity is the simplest, so this method is commonly used, although it depends on many factors: concentration, temperature, ion attraction, pH, acidity

➢ Degree of acetylication – DA

Because Chitosan is formed due to chitin reduction, the reduction of acetylic level will naturally affect the properties of chitosan The level of acetylation is calculated based on the ratio of mono bonds in which the acetylic acid is removed with the free amino group (when dissolved in a weak acid solution) in the polymer molecule The degree of degreasing is about 70-100% depending on the production technology

This parameter is important because it indicates the cation exchange capacity of the molecule after dissolving in weak acid solution The degreasing effect affects the solubility, biodegradability, antibacterial ability of the product

There are 5 factors that affect the acetyl reduction: alkalinity, reaction temperature, retention time, particle size and chitin pretreatment process

There are many methods of measuring the level of acetylation such as infrared and

UV spectra, acid-base titration, magnetic resonance, color absorption, etc Because there

is no certain standard, the number depends on the technology The magnetic resonance method has a higher accuracy, however, the price is expensive so people often use titration or color absorption method, these two methods give fast and simple results

➢ Purity

The purity of the product is an important property to evaluate the value of the product (especially in the biological and cosmetic field) The purity depends on the amount of ash, protein, solubility, as well as biological indicators (bacteria, mold enzymes, endotoxins) Even in field that require low chitosan values As wastewater treatment, purity also plays an important role because ash and protein levels have the ability to limit the activation level of amino groups

➢ Viscosity

The viscosity of chitosan solution depends on many factors such as: the reduction

of acetylic, molecular weight, concentration, ionic strength, pH, temperature

Viscosity is an important factor in determining the field of application of chitosan Moreover, the viscosity of Chitosan greatly affects the antibacterial ability of chitosan The increased antibacterial ability of E coli and Bacillus sp when the viscosity decreases from 1000 to 10 cP

The higher the volume of chitosan, the higher the viscosity

Many studies show that the viscosity of chitosan affects the chemical processing process Specifically when increasing factors such as grinding time, burning, sterilization by autoclaves, ultrasound, ozone The viscosity decreases from 248 to 32

cP when increasing the time for protein separation from 0 to 30 minutes

➢ Color

Color of chitin and chitosan due to carotenoid pigment The main component of carotenoids in crustaceans is astaxanthin Carotenoids are strongly associated with chitin molecules and are also related to the epithelial layer of the bone The level of carotenoids

in crustaceans is very low and depends on the pigments in the diet, organism size, maturity, genes The average of pigmentation pigments in Louisiana (1989), shrimp and crabs are around 108, 147 and 139 ppm

➢ Complexity ability

Chitosan has the ability to form complexes with metals In recent times, when chitin and chitosan are paid much attention to research, people have also discovered special coordination properties such as high elasticity, bioactive and biodegradable High of chitosan

In acidic environment, chitosan is a high molecular weight electrolyte with high

NH3+ group density, which makes chitosan more flexible than chitin Negative charged materials such as proteins, polysacrite anions, nucleic acids will interact and adhere to chitosan

Chitosan has the ability to combine with metal ions by adsorption into chelate rings, ion exchange or by coordination bonds, the importance of these processes is different for each metal So chitosasn is a very specific polymer for absorbing heavy metals, dye products, pigments, organic compounds,

➢ Antimicrobial

Many studies show chitosan is effective in preventing bacterial growth Antimicrobial ability of chitosan depends on molecular weight, concentration, type of bacteria, viscosity

0.1% Chitosan is effective for bactericidal against gram-positive bacteria (Listeria monocytogenes, Bacillus megaterium, B cereus, Staphylococcus aureus, Lactobacillus plantarum, L brevis, and L bulgaris) on gram bacteria negative (E.coli, Pseudomonas fluorescens, Salmonella typhymurium, and Vibrio parahaemolyticus)

0.1% chitosan has a volume of 746 KDa very effective in resistance to E.coli In addition, Chitosan has a molecular weight of 40 kDa which can prevent microorganisms S.aureus and E.coli at 0.5% concentration

2.2.6 Chitosan preparation process

Chitosan is chitin deacetylated product To prepare chitosan, it is necessary to undergo four main stages: protein reduction, demineralization, color reduction and acetylic group reduction Although chitin production process is quite simple, chitosan preparation process is quite complex and does not have specific standards

Dechlorination is the process of removing proteins in crustacean waste by soaking them in an alkaline solution (Muzzarelli, 1977) NaOH is often used for this process, in addition to Na2CO3, KOH, Na2S This process requires heating from 65℃ to 100℃ and

in the range of 0.5 to 6 hours This stage is the longest in the process, thanks to the long time that new enzymes can completely eliminate protein

After the protein reduction phase, the calcium carbonate in the crustaceans will be dissolved in acid conditions (Muzzarelli, 1977) In this process one can use acid HCl, HNO3, acetic acid and it lasts from 2 to 3 hours (Roberts, 1992)

The third step in preparing chitosan is color reduction The carotenoid specific to the color of crustaceans will be reduced by ethanol or acetone

Reduction of acetylic group is the last step in the step of changing from chitin to chitosan Acetyl reduction is used to distinguish different types of chitosan The acoustically modified threads are cooked after decolorization in alkaline solutions at temperatures from 100℃ to 180℃

Fig 2.4 Process of preparing chitosan

2.2.7 Overview of researched Chitosan

Chitosan research group is provided by NANO DHP Co., Ltd with purity of 98.6% and 91.6% deacetylation (FTIR) index determined by General Department of Quality Measurement Standards 8/3/2018

2.3 OVERVIEW OF TiO 2

2.3.1 Formations and crystal structures of TiO 2

Titanium dioxide is a heat-resistant, non-toxic and inexpensive white powder that is widely used in everyday life TiO2 is widely used in industry as a filler, specifically it is used in many paints, cosmetics, ceramic glazes In 1972, Fujishima and Honda invented the separation of water into O2 and H2 on TiO2 electrode by sunlight This event marks the beginning of a new era of photocatalyst applications

Later, nanometer-sized TiO2 crystalline powder in rutile, anatase, or rutile and anatase mixtures has been studied and applied in fields such as solar cells, electronics manufacturing, etc With high photocatalytic activity TiO2 nanomaterials are applied in the fields of environmental treatment such as: decomposition of toxic organic

compounds, water treatment, bactericidal, anti-mildew Especially combined with Another special property of the TiO2 thin film is the ability to prefer water when illuminated, while TiO2 also develops as a self-cleaning material (Tuyen, 2019)

Crystal structures of TiO2:

Fig 2.5 Crystal structures of TiO 2

Crystalline TiO2 exists in three formations: Anatase, Rutile và Brookite (Fig 2.5)

Table 2.2 Some structural properties of the shape of TiO2

Structural properties

Formations of TiO 2

Crystal system Tetragonal Tetragonal Octhorhombic

Network constant (Å) a=4.59 c=2.96 a=3.78 c=9.52

a=9.18 b=5.45 c=5.15

Ti-O bond length (Å) 1.95 (4) 1.94 (4) 1.87~2.04

Rutile is the most durable and popular form of TiO2, anatase and brookite, which are stable imitation forms When heated, they turn into rutile form

Fig 2.6 Crystal structures of TiO 2

The crystalline network structure of rutile, anatase and brookite is constructed from eight-sided TiO6 polyhedra connected to each other by the edge or through the common oxygen peak Each Ti4+ ion is surrounded by eight faces created by six O2 ions (Fig 2.6) However, the crystal networks of rutile, anatase and brookite differ by the deformation

of each of the eight-sided shapes and the way of binding between the 8-sided polyhedra The structural properties of the enmeshes are shown in Table 2.2

Differences in lattice structure lead to differences in electron density between two rutile and anatase forms of TiO2 and this is the cause of some differences in properties between them The nature and application of TiO2 depends very much on the crystal structure and particle size of these types of allotropes Therefore, when preparing TiO2

for practical application, it is often interested in such factors as: size, specific surface area and crystal structure of the product

In addition to the three crystal formations mentioned above, TiO2 also has amorphous form, which is precipitated product when prepared by hydrolyzing inorganic salts of Ti4+ or organic compounds of titanium in water at low temperature However, this form is not stable in air at room temperature or when heated, it turns into anatase form (Tuyen, 2019)

2.3.2 Properties of TiO 2

2.3.2.1 Chemical properties

TiO2 is relatively inert compounds chemically, does not react with water, dilute acid and alkaline solution (except HF) TiO2 slow action with high concentration H2SO4

solution when heated and reacts with the molten alkali (Nhu, 2018)

TiO2 works with alkaline flowing or soda according to the equation below:

TiO2 + 2NaOH → Na2TiO3 + H2O

TiO + NaCO → Na TiO + CO

Titanium oxides are stable to acid solutions TiO2 only be dissolved in acid solution

H2SO4 concentration of 70 - 80% when heated:

TiO2 + H2SO4 → H2[TiO(SO4)] + H2O

In the presence of residual SO42-, TiOSO4 and Ti(SO4)2 salts are converted to

Ti2(SO4)3 stable So empirically difficult modulation TiOSO4 solution relatively large concentration of TiO2 directly reacts with H2SO4 or HCl

TiO2 works with some other substances:

TiO2 + HF → H2TiF6 + H2O

TiO2 + NaHSO4 → Ti(SO4)2 + Na2SO4 + 2H2O

TiO2 + KHSO4 → Ti(SO4)2+K2SO4 + 2H2O

2.3.2.2 Photocatalytic properties of TiO 2

Fig 2.7 Schematic diagram of TiO 2 photocatalyst mechanism

In Fig 2.7 is the diagram of TiO2 photocatalyst mechanism principle Because the electronic structure is characterized by the valence band (VB) and the conduction band (CB), semiconductors such as TiO2 can act as catalysts for redox oxidation due to light and free radical formation *OH is the key issue of photocatalytic reaction on TiO2

Anatase TiO structure has a band gap of 3.2 eV Thus, under the effect of photon

Valence band

TiO2 + hv → e

-CB + h+

VB

When appears the positively charged holes (h+

VB) in the water environment, there are the reaction to create origin *OH

at TiO2 surface (Tuyen, 2012)

2.3.3 Factors affecting photochemical catalytic process of TiO 2

There are many factors that affect the photocatalytic feature of films such as fabrication method, crystalline crystallinity, calcination temperature, effective surface area, catalytic mass, light intensity However, the two main factors that determine the photocatalytic properties of TiO2 films are the effective surface area and the crystallinity

of the film In addition, if the photocatalytic reaction occurs in the visible light region,

it is important to consider an important factor that the absorbing edge of the material must be in this light area