Nghiên cứu hoạt hóa persulfate bằng sắt hóa trị không và UV nhằm tạo ra hệ oxi hóa kép để phân hủy một số thuốc nhuộm họ azo trong môi trường nước

i

MINISTRY OF EDUCATION AND
TRAINING

MINISTRY OF NATIONAL
DEFENCE

ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY

Nguyen Thanh Binh

STUDY ON ACTIVATED PERSULFATE
BY ZERO VALENT IRON AND UV TO
PRODUCE DUAL OXIDATION
SYSTEM TO DEGRADE SOME AZO
DYES IN WATER

CHEMICAL DOCTORAL THESIS


HA NOI - 2019


ii

MINISTRY OF EDUCATION AND
TRAINING

MINISTRY OF NATIONAL
DEFENCE

ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY

Nguyen Thanh Binh

STUDY ON ACTIVATED PERSULFATE
BY ZERO VALENT IRON AND UV TO
PRODUCE DUAL OXIDATION SYSTEM
TO DEGRADE SOME AZO DYES IN
WATER
Major: Theoretical and Physical Chemistry
Code: 9 44 01 19
CHEMICAL DOCTORAL THESIS
ACADEMIC SUPERVISORS:
1. Assoc. Prof. Dr. TRAN Van Chung
2. Prof. Dr. Sc. DO Ngoc Khue

HA NOI - 2019


i

ACKNOWLEDGMENTS
I assure that this is my own research. The research results shown in the
thesis are honest. Scientific conclusions of the thesis have never been published in
any other work. The scientific data were fully cited.
th

15

December 2019
Author

Nguyen Thanh Binh


ii

SPECIAL THANKS TO
I would like to express my deep gratitude to Assoc. Prof. Dr. Tran Van Chung
and Prof. Sc. Dr. Do Ngoc Khue for guiding deeply in helping me throughout the
process of implementing and completing the thesis.
I would like to express my sincere thanks to the Heads and Staffs of the New
Technology Institute/Academy of Military Science and Technology for supporting
and creating favorable conditions for me in the process of implementing the thesis.
I would like to thank the Heads of the Academy of Military Science and
Technology, the Training Department/Academy of Military Science and Technology for
helping me throughout the study, research and completion of the thesis.

I would like to express my thanks to Heads of College of Chemical Defense
Officer/Chemical Corps; Military Institute of Chemical-Environment/Chemical
Corps; Institute of Chemistry - Materials/Academy of Military Science and
Technology; Institute of Chemistry/Vietnam Academy of Science and Technology;
Department of Chemistry/VNU University of Science/Vietnam National University,
Hanoi; Department of Chemistry/Hanoi National University of Education helped,
during the thesis implementation.
Sincere thanks to my family, relatives, colleagues and friends for caring,
supporting, encouraging me to complete this project.

iii

TABLE OF CONTENTS
Page

1.1.

1.2.

ACKNOWLEDGMENTS

i

TABLE OF CONTENTS

iii

LIST OF SIGNS AND ABBREVIATION

vi

LIST OF TABLES

x

LIST OF GRAPHS

xii

INTRODUCTION

1

Chapter 1 OVERVIEW

5

The basic concept of the oxidation processes based on free radicals

5

1.1.1. The concept and classification of advanced oxidation processes

5

1.1.2. The advanced oxidation processes based on free hydroxyl radicals

7

1.1.3. The advanced oxidation processes based on free sulfate radicals

11

Status of treatment technology for textile dye wastewater

22

1.2.1. Concept, classification of dyes

22

1.2.2. Azo dyes

22

1.2.3. Dye-contaminated wastewater

27

1.2.4. Current situation of domestic and foreign researches on

28

treatment technology of textile dye wastewater
1.3.

Conclusion of chapter 1

31

Chapter 2 RESEARCH SUBJECT AND METHODOLOGY

33

2.1.

Research subject

33

2.2.

Instruments and chemicals

33

2.2.1. Instruments

33

2.2.2. Chemicals

34

Methods of analysis

34

2.3.1. High performance liquid chromatography method

34

2.3.2. Inductively coupled plasma - mass spectrometry method

37

2.3.3. The volumetric titration method determining the

37

2.3.

concentration of S2O8

2−


iv

2.4.

Experimental methods

39

2.4.1. Survey, evaluating the decomposition efficiency of AZOs in

39

systems: ZVI/AZOs, PS/AZOs, ZVI/PS/AZOs and ZVI/AZOs/UV,
PS/AZOs/UV, ZVI/PS/AZOs/UV
2.4.2. Survey of factors affecting on the degradation efficiency of

40

AZOs in systems: ZVI/PS/AZOs and ZVI/PS/AZOs/UV
•

−•

2.4.3. Qualitative survey of free radicals OH and SO4

42

in ZVI/PS/AZOs and ZVI/PS/AZOs/UV systems
•

−•

2.4.4. Quantitative survey of free radicals OH and SO4 in

44

ZVI/PS/AZOs and ZVI/PS/AZOs/UV systems
2.4.5. The theoretical equations applied in reaction kinetic research

44

2.4.6. The basis of quantum computing methods

48

2.4.7. Treatment of dye wastewater of La Phu, Duong Noi and Van

51

Phuc villages
3.1.

Chapter 3: RESULT AND DISCUSSION

52

Survey, evaluating the efficiency of the PS activation methods under

52

different conditions
3.1.1. The activated PS systems without UV

52

3.1.2. The activated PS systems with UV

56

3.1.3. Factors affect the AZOs decomposition in systems of

60

activated PS by ZVI under without and with UV conditions

3.2

Investigation of the kinetic characteristics of the AZOs

79

decomposition process in the activated persulfate system

3.2.1. The kinetic characteristics of the AZOs decomposition

80

in systems without UV
3.2.2. The kinetic characteristics of the AZOs decomposition in

82

system with UV
3.2.3. Results of calculating thermodynamic parameters according
to Arrhenius and Eyring equations for systems: ZVI/PS/AZOs and

86


v

ZVI/PS/AZOs/UV
3.3.

•

−•

Research to determine free radicals OH and SO4 in the activated

97

persulfate systems by ZVI without UV and with UV

•

−•

3.3.1. Qualitative study of free radicals OH and SO4 in the

97

ZVI/PS/AZOs system.
•

−•

3.3.2. Studying on quantification of free radicals OH, SO4 in the

99

activated persulfate systems by ZVI without and with UV
3.4.

Calculating some quantumn structural parameters and proposing

110

MO, AY and BT decomposition mechanism in the activated
persulfate system
3.4.1. Some structural parameters and ability of decomposing AZOs

110

3.4.2. The estimated mechanism of the AZOs decomposing in the

113

activated persulfate systems
3.5.

Application of the activated persulfate system with UV to treat azo-

118

contaminated wastewater from some textile dyeing villages
CONCLUSION

122

LIST OF PUBLISHED SCIENTIFIC WORKS

125

LIST OF REFERENCES Appendix

126


vi

LIST OF SIGNS AND ABBREVIATIONS
Signs

Meaning

λ

Wavelength (nm)

I

Light intensity (Lux)
#

Activated Enthalpy (kJ/mol)

∆S

#

Activated Entropy (J/mol.K)

Ψµ

Molecular orbital function µ

kB

Boltzmann constant (1.381.10

∆H

K

#

-23

-1

J.K )

The reaction equilibrium constant forming an activated complex
-1

-1

ε

Adsorption constant (M cm )

R

Gas constant (R=1.987 Cal/mol.K or R=8.314 J/mol.K)

h

Plank constant (h= 6.625.10

k

Reaction rate constant

Cµi

Linear combination factor

H(%)

Efficiency

Ea

Activation energy (J/mole)

Eµ

Total energy of the molecule

∆G

Free Gibbs energy (kJ/mol)

∆G

#

-34

Free activation Gibbs energy (kJ/mol)

T

Kelvin temperature (K)

C

Mole concentration (mole/L)

i

The orbital function i

v
E

ο

V
A
Tˆe

ˆ
H

J.s)

Light frequency (Hz)
Redox standard potential (V)
Volume (L)
Pre-exponential constant
The kinetic energy operator of electron
The Hamilton operator

vii

ˆ

U e −e

ˆ

U n −e

r

The potential energy operator of interaction
between nucleus and electron
The potential energy operator of interaction
between electron and electron
Reaction rate

Abbreviation Phrases are abbreviated
2,4- D
2,4-Dichlorophenoxy acetic acid
2,4,5-T

2,4,5-Trichlorophenoxy acetic acid

AC

Activated Carbon

AC-MW

Activated Carbon – Micro wave

ANPOs

Advanced Non-Photochemical Oxidation Processes

AO7

Orange 7 acid

AOPs

Advanced Oxidation Processes

APOPs

Advanced Photochemical Oxidation Processes - APOPs

AY

Alizarine Yellow R

AZOs

The general form, which represents one of the azo: MO, AY and BT

BOD

Biochemical Oxygen Demand

BT

Mordant Black-T

BTEX

Benzene, Toluene, Methylbenzene, Xylene

C.I

Color Index

COD

Chemical Oxygen Demand

DCE

1,2-dichloroethene

DNT

2,4-dinitro toluene

EDTA

Ethylene diamine tetra acetic acid

ETA

Ethanol alcohol

ETAD

The Ecological and Toxicological Association of Dyes and
Organic Pigments Manufacturers

HPLC

High Performance Liquid Chromatography

ICP-MS

Inductively Coupled Plasma- Mas Spectrometry

ISCO

In Situ Chemical Oxidation


viii

IUPAC

International Union of Pure and Applied Chemistry

LD50

Lethal dose 50%

MO

Methyl Orange

MTBE

Methyl tert-butyl ete

MW

Micro wave

NTA

Citric nitrile triacetate acid

PAHs

Polycyclic aromatic hydrocarbons

PCA

p-chloaniline

PCB28

2,4,4’- Trichloro biphenyl

PCE

Perchloro ethene

PS

Persulfate

PVA

Polyvinyl alcohol

SMT

Sunfamethazine

TBA

Tert-butyl alcohol

TCA

1,1,1-trichloro ethane

TCE

Trichloroethylene

TNT

Trinitrotoluene

TOC

Total organic carbon

TRGS 905

Technischen Regeln für Gefahrstoffe 905

UV

Ultraviolet

UV-Vis

Ultraviolet - visible

VOCs

Volatile organic compounds

ZVI

Zero valent iron


ix

LIST OF TABLES
Pages
Table 1.1.

The standard reduction potential EοOx/Re of some oxidation agents

5

Table 1.2.Some advanced oxidation processes without UV radiation

6

Table 1.3.Some advanced oxidation processes with UV radiation

6

Table 1.4.The reactions may occur during the Fenton process

9

Table 1.5.Some physical properties of persulfate salts

12

Table 1.6.Physical properties of MO

25

Table 1.7.Physical properties of AY

26

Table 1.8.

27

Physical properties of BT

35

Table 2.1.The retention time (tR) corresponding to the peak HPLC of MO,
AY and BT
Table 2.2.

The reaction rate constants between ETA, TBA with OH, SO4

•

−•

42

Table 2.3.

The qualitative experiements of OH, SO4 in ZVI/PS/AZOs system

•

43

−•

Table 3.1.Results of effecting of [ZVI] on the decomposition efficiency of

61

AZOs in systems ZVI/PS/AZOs (HAZOs %) and
Table 3.2.

ZVI/PS/AZOs/UV (HAZOs.UV %)
Results of effecting of [PS] on the decomposition efficiency of

64

AZOs in systems ZVI/PS/AZOs (HAZOs %) and
ZVI/PS/AZOs/UV (HAZOs.UV %)
Table 3.3.Results of effecting of [AZOs] on the decomposition efficiency

68

of AZOs in systems ZVI/PS/AZOs (HAZOs %) and
ZVI/PS/AZOs/UV (HAZOs,UV %)
Table 3.4.Results of effecting of pH on the decomposition efficiency of

72

AZOs in systems ZVI/PS/AZOs (HAZOs %) and
ZVI/PS/AZOs/UV (HAZOs,UV %)
Table 3.5.Results of effecting of temperature on the decomposition
efficiency of AZOs in systems ZVI/PS/AZOs (HAZOs %) and

ZVI/PS/AZOs/UV (HAZOs,UV %) (HAZOs,UV %).

76


x

Table 3.6.

The temperature effecting on the AZOs reaction kinetics of in
the ZVI/PS/AZOs system and the ZVI/PS/AZOs/UV systems

85

Table 3.7.

Activation energy Ea and pre-exponential constant (A) according

88

to Arrhenius equation for systems: ZVI/PS/AZOs and
ZVI/PS/AZOs/UV
#

#

#

Table 3.8.

Results of calculating ∆H , ∆S and ∆G according to Eyring

93

Table 3.9.

equation in the systems: ZVI/PS/AZOs and ZVI/PS/AZOs/UV
Reactions occuring in systems:

100

ZVI/PS/AZOs and ZVI/PS/AZOs/UV
Table 3.10.

−•

•

107

The calculation results of [SO4 ], [HO ] and k17, k18 in the
ZVI/PS/AZOs system and the ZVI/PS/AZOs/UV system
•

−•

Table 3.11.

The kinetic equations of reactions between AZOs and HO , SO4

109

Table 3.12.

in the ZVI/PS/AZOs system and the ZVI/PS/AZOs/UV system
The quantum parameters of MO, AY and BT molecular

111

Table 3.13.

The needed amount of PS and ZVI to wastewater

118

solutions of the textile dyeing villages
Table 3.14.

Results of pre-treatment and post-treatment analysis of textile dye
wastewater in villages of Duong Noi, La Phu and Van Phuc

119


xi

LIST OF GRAPHS
Pages
Figure 2.1.

Diagram of a reaction device for UV

33

heated activated persulfate process
Figure 2.2.

The calibration curve for determining MO concentration by HPLC

36

Figure 2.3.

The calibration curve for determining AY concentration by HPLC

36

Figure 2.4.

The calibration curve for determining BT concentration by HPLC

36

Figure 2.5.

The reaction process according to the theory of active

46

Figure 2.6.

Graph of dependence ln (k /T) on 1/T

47

Figure 3.1.

The decomposition efficiency of MO, AY and BT

52

in systems: 1. ZVI/MO, 2. ZVI/AY and 3. ZVI/BT
Figure 3.2.

The decomposition efficiency of MO, AY and BT

53

in systems: 1. PS/MO, 2. PS/AY and 3. PS/BT
Figure 3.3.

The decomposition efficiency of MO, AY and BT

54

in systems: 1. ZVI/PS/MO, 2. ZVI/PS/AY and 3. ZVI/PS/BT
Figure 3.4.

The decomposition efficiency of MO, AY and BT in systems:

56

1. ZVI/MO/UV, 2. ZVI/AY/UV and 3. ZVI/BT/UV
Figure 3.5.

The decomposition efficiency of MO, AY and BT in systems:

57

1. PS/MO/UV, 2. PS/AY/UV and 3. PS/BT/UV
Figure 3.6.

The composition efficiency of MO, AY and BT in systems:

58

1. ZVI/PS/MO/UV, 2. ZVI/PS/AY/UV and 3. ZVI/PS/BT/UV
Figure 3.7.

Comparing the decomposition efficiency of MO in systems:

59

1.ZVI/MO, 2.PS/MO, 3.ZVI/PS/MO and 4.ZVI/PS/MO/UV
Figure 3.8.

Comparing the decomposition efficiency of AY in systems:

59

1.ZVI/AY, 2.PS/AY, 3.ZVI/PS/AY and 4.ZVI/PS/AY/UV
Figure 3.9.

Comparing the decomposition efficiency of BT in systems

59

1.ZVI/BT, 2.PS/BT, 3.ZVI/PS/BT and 4.ZVI/PS/BT/UV
Figure 3.10.

Effect of [ZVI] on the MO decomposition efficiency
in systems: ZVI/PS/MO, ZVI/PS/MO/UV at 30 minutes

62


xii

Figure 3.11.

Effect of [ZVI] on the AY decomposition efficiency
in systems: ZVI/PS/AY, ZVI/PS/AY/UV for 30 minutes

62

Figure 3.12.

Effect of [ZVI] on the BT decomposition efficiency

62

in systems: ZVI/PS/BT, ZVI/PS/BT/UV for 30 minutes
Figure 3.13.

Effect of [PS] on the MO decomposition efficiency

65

in systems: ZVI/PS/MO, ZVI/PS/MO/UV for 30 minutes
Figure 3.14.

Effect of [PS] on the AY decomposition efficiency

66

in systems: ZVI/PS/AY, ZVI/PS/AY/UV for 30 minutes
Figure 3.15.

Effect of [PS] on the BT decomposition efficiency

66

in systems: ZVI/PS/BT, ZVI/PS/BT/UV for 30 minutes
Figure 3.16.

Effect of [MO] on the MO decomposition efficiency

69

in systems: ZVI/PS/MO, ZVI/PS/MO/UV for 30 minutes

Figure 3.17.

Effect of [AY] on the AY decomposition efficiency

70

in systems: ZVI/PS/AY, ZVI/PS/AY/UV for 30 minutes
Figure 3.18.

Effect of [BT] on the BT decomposition efficiency

70

in systems: ZVI/PS/BT, ZVI/PS/BT/UV for 30 minutes
Figure 3.19.

Effect of pH on the MO decomposition efficiency

73

in systems: ZVI/PS/MO, ZVI/PS/MO/UV for 30 minutes
Figure 3.20.

Effect of pH on the AY decomposition efficiency

73

in systems: ZVI/PS/AY, ZVI/PS/AY/UV for 30 minutes
Figure 3.21.

Effect of pH on the BT decomposition efficiency

73

in systems: ZVI/PS/BT, ZVI/PS/BT/UV for 30 minute
Figure 3.22.

Effect of temperature on the MO decomposition efficiency

77

in systems: ZVI/PS/MO, ZVI/PS/MO/UV for 20 minutes
Figure 3.23.

Effect of temperature on the AY decomposition efficiency

77

in systems: ZVI/PS/AY, ZVI/PS/AY/UV for 20 minutes
Figure 3.24.

Effect of temperature on the BT decomposition efficiency

77

in systems: ZVI/PS/BT, ZVI/PS/BT/UV for 20 minutes
Figure 3.25.

The effects of temperature on the MO graph of lnC/C0-t
in the ZVI/PS/MO system

81


xiii

Figure 3.26. The effects of temperature on the AY graph of lnC/C0-t
in the ZVI/PS/AY system

81

Figure 3.27. The effects of temperature on the BT graph of lnC/C0-t

82

in the ZVI/PS/BT system
Figure 3.28. The effects of temperature on the MO graph of lnC/C0-t

83

in the ZVI/PS/MO/UV system
Figure 3.29. The effects of temperature on the AY graph of lnC/C0-t

83

in the ZVI/PS/AY/UV system
Figure 3.30. The effects of temperature on the BT graph of lnC/C0-t

84

in the ZVI/PS/BT/UV system
Figure 3.31. Grap of lnk=f(1/T) according to Arrhenius equation in

87

systems: (a) ZVI/PS/MO; (b) ZVI/PS/MO/UV; (c)
ZVI/PS/AY; (d) ZVI/PS/AY/UV; (e) ZVI/PS/BT; (f)
ZVI/PS/BT/UV
Figure 3.32. Graphs of ln(k/T)=f(1/T) according to Eyring equation in

92

systems: (a) ZVI/PS/MO; (b) ZVI/PS/MO/UV; (c)
ZVI/PS/AY; (d) ZVI/PS/AY/UV; (e) ZVI/PS/BT; (f)
ZVI/PS/BT/UV
Figure 3.33. Graph C= f(t) of the MO decomposition in systems:

97

1.ZVI/PS/MO; 2.ZVI/PS/MO+ETA; 3.ZVI/PS/MO+TBA; 4. MO
Figure 3.34.

Graph C= f(t) of the AY decomposition in systems:

97

1.ZVI/PS/AY; 2.ZVI/PS/AY+ETA; 3.ZVI/PS/AY+TBA; 4.AY
Figure 3.35. Graph C= f(t) of the BT decomposition in systems:

98

1.ZVI/PS/BT; 2.ZVI/PS/BT+ETA; 3.ZVI/PS/BT+TBA; 4.BT
Figure 3.36. The charge density of atoms on the MO molecule

110

Figure 3.37. The charge density of atoms on the AY molecule

111

Figure 3.38. The charge density of atoms on the BT molecule

111

Figure 3.39. Comparing the decomposition kinetics of MO, AY and BT

112

in the activated PS system by ZVI without UV
Figure 3.40.

Comparing the decomposition kinetics of MO, AY and BT

110


xiv

in the activated PS system by ZVI with UV
Figure 3.41. Diagram of the eexpected MO decomposition mechanism

115

Figure 3.42. Diagram of the eexpected AY decomposition mechanism

116

Figure 3.43. Diagram of the eexpected BT decomposition mechanism

117

Figure 3.44. Decreasing of COD over time of Duong Noi,

119

La Phu and Van Phuc wastewater treatment
Figure 3.45. Photos of Duong Noi wastewater before and after treatment

120

Figure 3.46. Photos of La Phu wastewater before and after treatment

120

Figure 3.47. Photos of Van Phuc wastewater before and after treatment

120


1

INTRODUCTION
In recent years, advanced oxidation processes (AOPs) have been studied and
applied to treat wastewater and contaminated groundwater in the world and
Vietnam. The AOPs is based on the in-situ free radicals which are generated in
•

reaction. These free radicals have high oxidation activity like hydroxyl radicals OH
ο

−•

(E = 2.8 V) and sulfate radicals SO4

ο

(E = 2.6V). The free radicals selectively

react to all organic compounds in the water, decomposing and converting the
organic compounds into non-toxic or less toxic substances to humans and the
environment. The Advanced oxidation processes are known as: Fenton, Fenton •

photo, perozone, catazone, Fenton- electrochemical…The OH radicals are usually
produced by activating hydrogen peroxide or ozone with various activating agents
such as: transition metal ions, temperature, UV radiation,…[2], [11], [13], [17].
The method of treating organic polluted water by AOPs involves advantages
compared to traditional methods such as: fast treating time, mineralizing recalcitrant
toxic organic substances,...In some cases, AOPs are used as pretreatment methods
for biological methods. adsorption methods [1], [13], [17], [76], [89].
Recent scientific announcements by scientists on the researching and

application of other oxidants, such as persulfate and peroxymonopersulfate, are also
suitable for wastewater treatment of persistent organic pollutant. If these oxidants
are activated, they also produce free radicals which are higher oxidation activity
than the original ones. Persulfate, peroxymonopersulfate are not stronger than
hydrogen peroxide and ozone, but they are more durable than hydrogen peroxide
and ozone in solution, better soluble in water than ozone [43], [62], [85]. Specially,
−•

ο

the process of activating the persulfate produces free radicals SO 4 (E = 2.6V) and
•

ο

free radicals OH (E = 2.8V). Persulfate exists more longly in aqueous solutions,
which affects positively the decomposition of organic compounds in aqueous
environments [27], [57], [80].
Dyes are important and a long history of development in everyday life. At
first, dyes were prepared from plants and insects in nature. The dyeing industry is
development now. Dyes were mainly prepared by synthetic pathways. Azo dyes


2

occupy more than 50% of the dye global trade. Some azo dyes have been found to
cause cancer, mutations in genes and are banned worldwide. However, they are still
produced and used on a large scale in the dyeing industry now. Because they are
low production cost, easy to synthesize and some good color properties. The bonds
in the azo molecules are quite stable, showing the ability to decompose and

accumulate in the environment[18], [22], [59].
The textile industry consumes a large amount of clean water and also
discharges a similar amount of wastewater which is complex composition and
properties. This wastewater contains residual dyes from dyeing process (occupying
about 10 to 15 % of the dye initial amount) and has color, temperature, content of
COD, BOD and surfactants being very high [2], [41], [59], [85].
Vietnam had a strong textile industry in recent decades, which brings many
jobs and income to workers. Besides, it also releases a large amount of wastewater
polluting environment [2], [41], [59], [85].
The problem of textile dye wastewater is always concerned by domestic and
foreign scientists. Although there have been many traditional methods of treating
textile dye wastewater, the AOPs especially based on. In recent years, advanced
oxidation methods, especially persulfate-based AOPs have been studied, applied
and have shown superiority in the process of decomposing organic matter in water
environment. The AOPs based on persulfate having potential to treat textile dye
wastewater [1], [7], [13], [22], [41], [59]. Therefore, this thesis topic was chosen:
"Study on activated persulfate by zero valent iron and UV to produce dual
oxidation system to degrade some azo dyes in water".
* Objectives of the thesis:
Study of dual oxidation formation in persulfate-containing solution in
combination with zero valent iron powder (ZVI) and UV; Application of dual
oxidation system to decompose some azo compounds: Methyl orange (MO),
alizarine yellow R (AY), modant black-T (BT) and treatment of textile dye village
wastewater contaminated with azo dye.


3

* Main contents of the thesis:
- Researching on activated persulfate by ZVI power combined with UV

through evaluating the decomposition efficiency of MO, AY and BT. Choose the
systems have the best decomposition of azo dyes. Studying and evaluating factors
affecting the efficiency of MO, AY and BT dye decomposition in activated
persulfate system by ZVI without UV (ZVI/PS/AZOs) and with UV
(ZVI/PS/AZOs/UV).
- Researching reaction kinetics, calculating the thermodynamic quantities of
the decomposition processes of MO, AY and BT in the activated persulfate systems
by ZVI combined with UV and with out UV. Studying to determine and quantify
•

−•

OH, SO free radicals in the activated persulfate systems.
- Calculating molecular structure parameters and proposing mechanism of MO.

AY and BT decomposition in the activated persulfate systems.
- Study on the application of activated persulfate system by ZVI combined
with UV to treat azo-contaminated wastewater in some textile dye villages: Duong
Noi, La Phu and Van Phuc.
* Study methods:
Researching theory, consulting documents, overview issues related to subjects
and researching content.
The analytical methods were used in this thesis: Using HPLC, ICP-MS,
volumetric titration, colorimetric and COD methods to study the characteristics of the
decomposition processes of azo dyes and wastewater containing azo dyes. Building up
−• •

mathematical models to approximate the concentration of SO 4 , OH. This thesis is
based on the kinetic theory of Arrhenius and Eyring equation to calculate some
thermodynamic quantities. Using HyperChem 8.0 software to calculate quantum

parameters of methyl orange, alizarin yellow R and mordant black T.

* The scientific and practical meaning of the thesis:
Research results of the thesis contribute to clarify and develop kinetics of
AOPs processes based on activated persulfate by ZVI and UV to decompose some
azo dyes in the wastewater and creating a basis for development diversify methods


4

of treating organic pollutants in the wastewater in general and azo-contaminated
wastewater in particular.
* Outline of the thesis:
Chapter 1: Overview (4 pages); Chapter 2: Research subject and methodology
(27 pages); Chapter 3: Results and discussions (69 pages); Conclusion (3 pages);
Reference (9 pages).


5

Chapter 1. OVERVIEW
1.1. The basic concept of the oxidation processes based on free radicals.
1.1.1. The concept and classification of advanced oxidation processes.
1.1.1.1. The concept of advanced oxidation processes.
Advanced Oxidation Processes (AOPs) are a set of oxidation processes of
•

−•

organic substances based on free radicals: OH, SO4 ,… produced on in-situ in the

process of treating contaminated water [1], [7], [11], [12], [17], [29], [30], [37],
[47], [51], [55], [56], [64], [65], [68], [80].
•

−•

The standard reduction potential of free radicals OH, SO4 (E
E

ο
SO4−•

ο
•OH

= 2.8V,

= 2.6 V) is much higher than other conventional oxidants, it is shown in

Table 1.1. These free radicals have strong oxidizing activity and decomposition
reaction of most organic compounds when they interact with each other.
Table 1.1. The standard reduction potential E

Oxidizing agents
•

E

ο

ο

Ox/Re

of some oxidizing agents.

Ox/Re

(V)

2.80

OH
−•

SO4
O3
H2O2
MnO4

−

Cr2O7

2−

ClO2
HClO
HIO

−

Cl2
Br2
I2
2−

2.60
2.07
1.78
1.68
1.59
1.57
1.49
1.45
1.36
1.09
0.54
2.1

S2O8
1.1.1.2. The classification of advanced oxidation processes.
According to the United State Environmental Protection Agency (USEPA)
based on the characteristics of the process with or without UV radiation energy to
classify advanced oxidation processes into two groups.


6

Table 1.2. Some advanced oxidation processes without UV radiation [1], [7], [12].

Reactants
2+

Reactions
2+

−

3+

•

Name of processes
Fenton
Perozone
Catazone
Oxidation of
electrochemical

H2O2 and Fe
H2O2 and O3
O3 and catalysts

H2O2 + Fe →Fe +OH + OH
•
H2O2 + 2O3 → 2 OH+ 3O2
•
3O3 + H2O → 2 OH+ 4O2

H2O and

•

electrochemical energy

H2O → OH+ H

H2O and ultrasound
energy

H2O → OH+ H
(20- 40 kHz)

•

•

Ultrasound

H2O and high energy

H2O → OH+ H
( 1-10 Mev)

•

•

High energy

SO

2-

2

8

2-

SO
2

8

SO
2

2-

and transition
metals

•

−•

+SO +

S O 2-+Mn+ →Mn+1
2

8

radiation
4

2−

SO4
−•

2-

S O → 2SO

and ultrasound

2

energy

8

2-

−•

8

4

S O → 2SO
2

8

ο

by transition metals
Activated persulfate

4

by ultrasound energy

(20 - 40 kHz)

and heat energy

Activated persulfate

Activated persulfate
by heat energy

(40 -70 C)

Table 1.3. Some advanced oxidation processes with UV radiation [1], [7], [12].
Reactants

Reactions

Name of process

•

H2O2 and UV radiation

H2O2 → 2 OH
(λ= 220 nm)

O3 and UV radiation

O3 + H2O → 2 OH + O2
(λ= 254 nm)

H2O2/O3 and UV
radiation

H2O2 +O3 +H2O → 4 OH+O2
(λ= 254 nm)

3+

Fe +H2O → OH +Fe + H
− •
2+
3+
Fe +H2O2→Fe +OH + OH

H2O2/Fe and UV
radiation

•

•

3+

2+

+

2

28

and UV radiation

+

+

TiO2 → e + h
(λ > 387 nm)
•
+
+
h + H2O → OH + H

-

•

h + OH → OH + H
SO

O3/UV

•

−

TiO2 and UV radiation

H2O2/UV

2-

S2O8 → 2SO4
(λ= 254 nm)

−•

H2O2/O3/UV
Photo-Fenton
Photo- semiconductor
catalysts

+

Activated persulate by
UV radiation


7

- The advanced non-photochemical oxidation processes (ANPOs) such as
Fenton, perozone, catazone, oxidation of electrochemical, … shown in Table 1.2.
- The advanced photochemical oxidation processes (APOPs) such as processes of
UV/H2O2, UV/O3, UV/H2O2+O3, UV/H2O, photo-Fenton, UV/TiO2, UV/S2O8,…

shown in Table 1.3.
In recent years, scientists on the world have been interested in studying the
reaction with advanced oxidizing agents and reactions. Because of the advanced
oxidation processes, there are many advantages over traditional oxidizing agents
such as stronger oxidation at room temperature, faster mineralization time of
organic compounds in certain conditions.
1.1.2. The advanced oxidation processes based on free hydroxyl radicals.
1.1.2.1. Characteristics and properties of free hydroxyl radicals.
The free hydroxyl radicals are neutrality on electricity and formed in many
•

different ways such as: catazone, perozone, Fenton, photo-Fenton,… The OH
radicals do not exist available as conventional oxidizing agents. but that is generated
•

in-situ during the reaction process. The OH radicals have a very short half-life time
(t1/2= 10µs) [42], but they are constantly produced and lost during the reaction
•

ο

occurred. The standard reduction potential of OH (E = 2.80 V) is quite high. The
•

OH radical has a strong oxidizing activity compared to conventional oxidizing

agents (Table 1.1) and is capable of oxidation reaction with most organic substances
in aqueous environments.
•

The OH radicals can react with most organic pollutants in the following ways:

- The addition reaction with linear unsaturated hydrocarbon or aromatic ring
compounds, creating new hydroxylate radicals:

•

OH+CH=CH
2

2

→ • CH -CH(OH)
2

(1.1)

2

hydrocarbon

- The reaction separates H from saturated or unsaturated
compounds to form water and active organic radicals:
•
•
3
OH + CH -CO-CH
→ CHCOCH
3

2

3

+ HO
2

- The electron exchange reaction creates the new active ion radicals:

(1.2)


8

•

OH + CH

-S-C H

3

→ [CH -S-C H +•
] +OH−

5

6

3

6

(1.3)

5

The reaction process continues to be developed by new free radicals generated
in the chain reaction until complete digestion or the chain reaction is interrupted.
The oxidation of pollutants in water is "inorganization" or "mineralizing"
process which converts organic pollutants into simple and non-toxic inorganic
substances.
Popular characteristics of the oxidation reaction based on conventional
oxidizing agents (KMnO4, O3, H2O2,...) with organic pollutants in the water
solution are selective reactions or thorough and low reaction efficiency. Meanwhile,
•

the OH radicals react non-selectively with most organic substances (including

inorganic compounds such as CN- ions) with a very fast rate. For example the
•

9

reaction rate constant of OH radical with phenol (about 10 to 10
fast from 10

12

to 10

13

-3

10

-1 -1

M s ) is as

-1 -1

times as that with O3 (10 M s ).

1.1.2.2. Methods of generating hydroxyl radicals.
•

a. The OH radicals are created from the O3/H2O process.

Using ozone in the treatment of polluted water by organic matter by bubbling
•

ozone into solution, O3 combines and reacts with H2O to form free OH radicals
which decompose organic matter in polluted water [12], [13], [88].
O3
O3 itself is also

•

(1.4)

+ H2O → O2 +2 OH
a strong oxidizer (E

ο
O3=

2.07

V) and capable of directly

oxidizing organic matter, but the oxidation reaction is slow (compared to the
•

hydroxyl radical). Whereas the OH radicals react non-selectively with all organic
matter with a very fast reaction rate and can completely mineralize organic
compounds. Despite its high oxidation capacity, the application of ozone gas to
mineralize completely toxic, persistent organic compounds still has many
difficulties [88]. The main limitation of the application of O 3 in wastewater

treatment is due to the high investment, operating and maintenance costs, in
addition, the by-products of reactions can cause secondary pollution [12], [13], [88].