Since the late 20th century, there have been many warnings
about the existence of phenol and phenol compounds in the
environment, especially the water environment. Phenol pollutes the
natural water environment due to its presence in many industrial waste
streams such as petrochemical, coke, steel . [1-3]. Although widely
used in many industries, science has proved that phenols are toxic to
humans and organisms. Thus, phenol pollution in water is becoming a
serious problem for many countries, including Vietnam. Many methods
have been applied to treat phenol in water such as adsorption, biology,
catalytic wet oxidation . However, it is often necessary to combine two
or more technologies to completely remove phenol from the waste
stream. Recently, catalytic Ozonation Process (COP) or catazon has
emerged as a new strategy for the treatment of persistent organic
substances and has proven very effective in treating wastewater.
contains phenol compounds. This method has many advantages such as
no problems related to chemicals, high efficiency of pollutant
decomposition, fast processing time, simple equipment, easy to install,
no waste sludge and In particular, ozone can be
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MINISTRY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY
----------------&---------------
NGUYEN THANH THAO
STUDY ON PHENOL TREATMENT IN COKING
WASTEWATER BY OZONATION PROCESS
COMBINED WITH CATALYST
Major: Environmental Engineering
Code: 9.52.03.20
SUMARY OF DOCTORAL THESIS OF
ENVIRONMENTAL ENGINEERING
Hanoi, 2019
The work was completed at Graduate University of Science and
Technology – Vietnam Academy of Science and Technology
Scientific Supervisor 1: PGS.TS. Trinh Van Tuyen
Scientific Supervisor 2: PGS.TS. Lê Truong Giang
1
st
Reviewer:
2
st
Reviewer:
3
st
Reviewer:
The thesis will be defended at the Academic Review Board of the
Graduate University of Science and Technology - Vietnam Academy of
Science and Technology, 18 Hoang Quoc Viet Street, Cau Giay District,
Hanoi, Vietnam athourdatemonthin 2019
The thesis can be found at:
- Vietnam National library
- Library of the Graduate University of Science and Technology
PUBLISHED ARTICLES USED IN THIS THESIS
1. Nguyen Thanh Thao, Trinh Van Tuyen, Le Truong Giang.
Study on Pre-Treatment of Phenol, COD, Color in the coke
wastewater by ozonation Process. Journal of Science and
Technology, ISSN 2525-2518, 55, (4C) (2017), pages 271-276
2. Nguyen Thanh Thao, Le Trung Viet, Nguyen Quang Trung.
Development of method for analysing major phenol derivatives in
coke wastewater. Jounal of Analytical Sciences, ISSN 0868-3224
(22) (2017), pages 30-36
3. Nguyen Thanh Thao, Trinh Van Tuyen, Le Truong Giang.
Evaluating chemical compounds in coke wastewater of Thai
Nguyen iron and stell SJC, Thai Nguyen province. Jounal of
Analytical Sciences, ISSN 0868-3224, (23), number 1/2018, pages
22-29.
4. Thao T Nguyen, Tuyen V Trinh, Dung N Tran, Giang T Le,
Giang H Le, Tuan A Vu and Tuong M Nguyen. Novel FeMgO/CNT
nano composite as efficient catalyst for phenol removal in
ozonation process. Materials Research Express. Volume 5, Number
9, 095603, 2018.
5. Hoang Hai Linh, Nguyen Quang Trung, Nguyen Thanh Thao.
Removal phenol in coke wastewater by ozone combine with
modified laterit. Jounal of Analytical Sciences, ISSN 0868-3224,
(23), number 4/2018, pages 295-304.
6. Nguyen Thanh Thao, Trinh Van Tuyen, Nguyen Quang Trung.
Simultaneous determination of hydroquinone, catachol and
benzoquinone during phenol ozonation by high-perfomance liquid
chromatoghaphy. Jounal of Analytical Sciences, ISSN 0868-3224,
(21), number 3/2016, pages15-24.
7. Nguyen Thanh Thao, Trinh Van Tuyen, Le Truong Giang.
Study on the kinetics of phenol degradation in aqueous solution
by ozonation process at neutral media. Jounal of Analytical
Sciences, ISSN 0868-3224 (has been approved for publishment).
8. Thao Nguyen Thanh, Tuyen Trinh Van, Giang Le Truong,
Tuan Vu Anh. Study on Phenol treatment by Catalytic Ozonization
using Modified dolomite. Jounal of Analytical Sciences, ISSN
0868-3224 (has been approved for publishment).
9. Nguyen Thanh Thao, Trinh Van Tuyen, Le Truong Giang.
Study on degradation of phenol in aqueous solution by ozonation
combined with FeMgO/CNT. Jounal of Analytical Sciences, ISSN
0868-3224 (has been approved for publishment).
1
INTRODUCTION
Since the late 20th century, there have been many warnings
about the existence of phenol and phenol compounds in the
environment, especially the water environment. Phenol pollutes the
natural water environment due to its presence in many industrial waste
streams such as petrochemical, coke, steel ... [1-3]. Although widely
used in many industries, science has proved that phenols are toxic to
humans and organisms. Thus, phenol pollution in water is becoming a
serious problem for many countries, including Vietnam. Many methods
have been applied to treat phenol in water such as adsorption, biology,
catalytic wet oxidation ... However, it is often necessary to combine two
or more technologies to completely remove phenol from the waste
stream. Recently, catalytic Ozonation Process (COP) or catazon has
emerged as a new strategy for the treatment of persistent organic
substances and has proven very effective in treating wastewater.
contains phenol compounds. This method has many advantages such as
no problems related to chemicals, high efficiency of pollutant
decomposition, fast processing time, simple equipment, easy to install,
no waste sludge and In particular, ozone can be.
Some solid catalysts have been shown to increase the efficiency
of phenol removal in water by catalytic ozonation process such as metal
oxides Mn/Al2O3, MgO, ZnFe2O4, metals on carbon materials such as
AC/Fe2O4, CNT/Fe2O3, CNF/Fe2O3 or minerals such as perovskite,
honeycomb ceramic material ... [6-10]. Carbon nanotubes (CNTS)
materials with the advantages of large surface area, unique structure
have been becoming a new, promising and advanced class of materials
in this field of catalytic synthesis. However, the catalysts based on this
material are mainly applied to remove phenol in water by catalytic wet
oxidation and adsorption method, which is rarely studied to treat phenol
by heterogeneous catalytic ozonation process. FeMgO/carbon nanotube
composite (FeMgO/CNT) and dolomite modified by KOH (M-Dolomit)
2
are the first time to be evaluated for catalytic role for the removal
phenol in water by heterogeneous catalytic ozonation process.The thesis
with the title "Study on phenol treatment in coking wastewater by
ozonation process combined with catalyst” has been conducted to study
the treatment of coking wastewater containing toxic phenol compound
by ozonationprocess combined with heterogeneous catalysts, using
available catalyst materials produced in Vietnam with low cost and
environmentally friendly.
Objectives of thesis:
Study on phenol treatment in water by ozonation process
combined with catalysts. An empirical kinetic model and one quadratic
regression equations were built based on experimental data for
destroying phenol by heterogeneous catalytic ozonation process with
response variables (initial pH, ozone concentration, catalyst
concentration and reaction time). Application of phenol treatment in
coking wastewater.
Contents:
1. Overview of phenol pollution status in coking effluent, sources,
composition, toxicity and phenol treatment technologies in these kinds
of wastewater.
2. Study on phenol treatment in water by heterogeneous catalytic
ozonation process with two catalytic materials selected: FeMgO/CNT
and M-Dolomite. From studied results, select one best catalytic material
for further phenol treatment.
3. Develop the empirical kinetic model and quadratic regression
equations for decomposing phenol by O3/FeMgO/CNT process with
response variables (initial pH, ozone concentration, catalyst
concentration and reaction time).
4. Treatment of coking wastewater of Thai Nguyen Iron and Steel JSC
with pilot scale.
3
New contributions of the thesis:
- The first time, FeMgO/CNT composite and M-Dolomite materials
prepared from inexpensive clay minerals have been evaluated catalytic
characteristic to decompose phenol in the water by heterogeneous
catalytic ozonation process.
- Development of the empirical kinetic model and the quadratic
regression equations for decomposing phenol in water by
O3/FeMgO/CNT process with response variables.
CHAPTER 1. LITERATURE OVERVIEW
1.1.Technology for coke production and source of coking
wastewater
1.2. Phenol toxicity and treatment methods for the removal of
phenol from coking wastewater
1.3. Ozone-Based Oxidation processes
1.4. Experimental planning and Box-Hunter experimental planning
CHAPTER 2. SUBJECTS AND RESEARCH METHODS
2.1. Objects and scope of the thesis
Water samples containing phenol prepared from phenol crystals
and coke wastewater samples were taken from Thai Nguyen Iron and
Steel Joint Stock Company and Formosa Ha Tinh Steel Corporation.
2.2. Chemicals and equipments
2.3. Research methods
2.3.1. Experimental methods
2.3.1.1. Experimental description
2.3.1.2. Evaluation on the catalytic activity of materials
2.3.1.3. Study on phenol treatment in water by ozone and heterogeneous
catalytic ozonation processes
2.3.1.4. Development of an empirical kinetic model for treatment of
phenol by O3/FeMgO/CNT process
2.3.1.5. Development of a quadratic regression equations for treatment
of phenol by O3/FeMgO/CNT process
4
2.3.1.6. Treatment of coke wastewater of Thai Nguyen Iron and Steel
Joint Stock Company by O3/FeMgO/CNT process
2.3.2. Field survey and sampling methods
2.3.3. Analysis methods
2.3.4. Data processing methods
2.3.4.1. Efficiency of pollutants removal
2.3.4.2. Method of calculating pseudo first order reaction rate
constant
2.3.4.3. Method of developing an empirical kinetic model
2.3.4.4. Method of developing a quadratic regression equation
CHAPTER 3. RESULTS AND DISCUSSIONS
3.1. Characteristics of coking waste water
The analysis results of 16 samples of coking wastewater were
taken from Thai Nguyen Iron and Steel Joint Stock Company and
Fomosa Ha Tinh Steel Corporation show that this wastewater has a
pungent odor (smell of phenol) and many parameters with high
concentration such as color, COD, BOD5, CN
-
, phenols (phenol and
total derivatives), phenol, total nitrogen, NH4-N. Other parameters such
as heavy metals, total grease, total phosphorus, Cl
-
, S2
-
, residual chlorine
are quite low. The pH of the samples ranged from 6.7 to 9.5 (average at
7.9). For Fomosa samples, the pH ranged from 6.7 to 8.4 (average 7.6).
The wastewater is dark brown with average color 673 - 712 Pt/Co. TSS
parameter is from 132 - 357 mg/L. However, the total organic
compounds (COD) is high, ranging from 5.014 to 6.350 mg/L (5.794
mg/ L on average) for Thai Nguyen samples, higher than the average
3,871 mg/L in Fomosa samples. BOD5 in all samples has a ratio of 30-
33% compared to COD. Phenol and CN
-
are two parameters with a high
concentration in all samples. The content of phenols in Thai Nguyen
samples has a high content in the range of 850 - 1,052 mg/L (average
949.3 mg/L), higher than 738 mg/L as the average value of Fomosa
samples. Coking wastewater has a high COD parameter because it is
5
complex wastewater. Besides of high levels of phenol, there are many
derivatives of phenol as well as other organic substances. The average
concentration of phenol in Thai Nguyen samples is 665 mg/L, higher
than the average of 629 mg/L in Fomosa ones. The ratio of derivatives
and phenols of all samples varied greatly, accounting for 14.7 - 70%.
CN
-
concentration averaged 31.5 mg/L for Thai Nguyen samples and
26.5 mg/L for Fomosa ones.
06 samples of coking wastewater collected at Thai Nguyen Iron
and Steel Joint Stock Company were analyzed 09 derivatives of phenol
commonly found in this kind of water [19, 31, 54] and simultaneously
analyzed 943 organic substances by AIQS - DB software by GCMS.
The results reveal four highly concentrated derivatives, including: 2-
methylphenol (3.1 - 33.7 mg/L), 3 methylphenol (7.4 - 46.69 m/L), 4 -
methylphenol (3.1, -16.6 mg/L); 3,5 - dimethylphenol (8.9 - 35.4 mg/L)
and 2.5 - dimethylphenol (1.23 - 20.8 mg/L). Other derivatives such as
2,3-dimethylphenol; 3,4-dimethylphenol, 2,4-dimethylphenol; 2,6-
dimethylphenol are also detected but in small concentrations.
3.2. Evaluation of the catalytic activity of materials
3.2.1. Evaluation of adsorption capacity of dissolved O3 on material
surfaces
Fig 3.1: Dissolved O3
concentration in solution with
and without catalyst
Fig 3.2: The effects of tert-butanol on the efficiency of
phenol decomposition with and without catalyst
The results show that the concentration of dissolved O3 in the
solution with catalysts were always higher than without catalyst. When
6
there is no catalyst, the measured concentration are 2.8; 3.6; 3.2; 3 mg/L
at 5; 10; 15; 20 minutes, higher than 2.4; 3.2; 2.7; 2.5 mg/L in the
presence of M-Dolomite and 2; 2.8; 2.5; 2.2 mg/L with FeMgO/CNT
catalyst (Fig 3.1). That indirectly proves the selected materials have
catalytic activities. The dissolved O3 produced in the solution has been
adsorbed and decomposed on the surfaces of the material to form free
radicals
OH. The analytical results of phenol adsorption capacity on
the surface of FeMgO/CNT and M-Dolomite catalyst in 60 minutes
show that phenol is not adsorbed on the surface of catalysts.
3.2.2. Evaluation of the role of free hydroxyl radicals contribute to
phenol treatment by heterogeneous catalytic ozonation process
The presence of tert-butanol in solution reduced the efficiency
of phenol decomposition in both cases with and without catalyst. Fig 3.2
shows the phenol decomposition efficiency are 60.7; 70.9; 76.5; 82.2;
86.2% in ozonation process corresponds to pH values: 3; 5; 7; 9; 11 but
reduced to only 50; 53; 54; 55; 52% in ozonation process with tert-
butanol.
The efficiency of phenol decomposition without tert-butanol are
41-78.8%; 50.7-85.5% and 74.1-90.1% corresponding to processes O3;
O3/M-Dolomite; O3/FeMgO/CNT processes when pH values increase
from 3 to 11 but only reach 37.5 - 55%; 20.1 - 25.2%; 54.3 - 57.2% with
scavenger. In particular, the O3/M-Dolomite+tert-butanol process is
affected highly. In alkaline media, the phenol decomposition efficiency
decreases much more than the neutral and acidic media. Due to in
alkaline media, reaction mechanisms by
•
OH played a key role.
3.2.3. Evaluate concentration of metals being released into the
solution and contribute to the efficiency of phenol decompose by
homogeneous catalytic ozonation process
The results showed that the Fe, Mg metals in FeMgO/CNT and
Ca, K, Mg in M-Dolomite were dissolved into phenol solution increase
to the maximum concentration and then gradually decreased. The
7
concentration of Fe and Mg reaches maximum at concentrations of
0.044 and 0.067 mg/L after 20 minutes and then decreases to 0.018 and
0.03 mg/L after 60 minutes. However, the concentration of Mg and Fe is
quite small. For M-Dolomite catalysts, the concentrations of metals Ca,
K, Mg reach maximum after 10 minutes of reaction at the values of
0.35; 1.19 and 26.4 mg/L but decreased to 0.18; 0.7; 21.4 mg/L after 60
minutes. Among the 3 metals in the M-Dolomite catalyst, metal K is
released into the solution with the concentration up to 21.4 mg/L.
The Fe, Mg metals with the maximum concentration released
into the solution in the composition of FeMgO/CNT materials do not
show the catalytic activity of decomposing phenol by homogeneous
catalytic ozonation process. In contrast, mixtures of Ca, K, Mg metals in
M-Dolomite material composition at concentrations of 0.35; 1.19 and
26.4 mg/L represent catalytic activity. After 60 minutes of reaction,
phenol decomposition efficiency reached 64.8%, an increase of 8.8%
compared to the efficiency achieved by O3 process.
3.2.4. Evaluate the ability of adsorption of phenol on the surface of
the catalysts
Results of the investigation of phenol adsorption capacity on the
surface of FeMgO/CNT and M-Dolomite materials in 60 minutes
showed that phenol is almost unabsorbed on the surface of materials.
This proves that the adsorption process does not contribute to the phenol
decomposition efficiency for O3/FeMgO/CNT and O3/M-Dolomite
processes.
3.3. Study on phenol treatment in water by ozone and
heterogeneous catalytic ozonation processes
The removal efficiency of phenol, COD, TOC and apparent
reaction rate constant with (kcata) and without catalyst (k) tend to
increase with increasing pH solution. When there is no catalyst, k
increases 2.8 times when the pH of the solution increases from 3 to 11.
kcata increase gradually from 0.0122 - 0.0312 (1/min) in O3/M-Dolomite
8
process when increasing pH from 3-11 but increase from 0.022 to
0.0392 (1/min) with O3/FeMgO/CNT process.
The presence of FeMgO/CNT catalyst has accelerated the
decomposition rate of phenol with kcata fold 1.4 - 2.5 times higher than k
without catalyst when increasing pH from 3-11 but only fold 1.1- 1.4
times with M-Dolomite catalyst (Fig 3.8). The increasing k value when
the pH increase of the thesis is also different from the results of the
research by Yousef Dadban Shahamat and colleagues (2014) [9]. The
study of Yousef Dadban Shahamat showed that k decreased when
increasing the pH of phenol solution from 4 to 6 and then increased
when pH increased from 6-10 when phenol was treated with O3 process.
3.3.1.Effect of pH on phenol treatment efficiency
Fig 3.7: Effect of pH on the ability to
decompose phenol with and without
catalyst
Fig 3.8: Effect of pH on the apparent
reaction rate constant of phenol
decomposition with and without catalyst
The removal efficiency of COD by O3 process reached 13.4 -
29.3%, corresponding to pH from 3-11 but increased to 21.2 - 33.2%
with O3/M-Dolomite process and 34,3 - 43 , 2% with O3/FeMgO/CNT
process. Similar to COD, TOC mineralization efficiency reaches 11.1-
22% with O3/M-Dolomite, 6.1 to 18.5% higher than the efficiency of O3
process. O3/FeMgO/CNT process gives the highest mineralization
efficiency, reaching 21 - 29.2% when increasing pH from 3 - 11. pH = 7
was chosen as phenol solution for further studies of the phenol treatment
in water by ozone and heterogeneous catalytic ozonation processes.
9
3.3.2. Effect of catalyst concentration on phenol treatment efficiency
The removal efficiency of phenol, COD, TOC, and apparent
reaction rate constants of phenol decomposition tend to increase with
increasing catalysts concentration. Figure 3.12 shows the removal
efficiency of phenol after 60 minutes with O3/FeMgO/CNT process with
increasing catalyst concentrations: 0; 0.5; 1; 2; 3; 3.5 g/L corresponds to
56; 72.1; 78.1; 79.2; 86.3; 87.3%. The cause of increased removal
efficiency of phenol when increasing FeMgO/CNT catalyst
concentration is due to: 1) The surface area of catalysts increases with
higher amount of catalyst, increasing the amount of O3 molecules
adsorbed on the surface. The hydroxyl radicals
•
OH produced by the O3
self-decomposition reaction increased [110, 112]. 2) The amount of
CNT material participating in the reaction is higher, leading to an
increase in the amount of
•
OH producing the reduction reaction (e) of O3
on the CNT surface, increasing the solution pH. Increased pH increases
•
OH produced by the O3 self-decomposition reaction increased. 3). The
number of ions Fe
2+
, Fe
3+
and MgO in FeMgO/CNT material also
increase when the amount of catalyst increased. The chain of reactions
produced
•
OH is more due to the reaction of O3 with the active
components of the catalyst. The amount of
•
OH in the solution
increases, increasing the efficiency of phenol decomposition. Phenol
decomposition efficiency reaches 56; 59.4; 63.7; 70.1; 80.3; 81% in the
O3/M-Dolomite process corresponds to a catalyst concentration of 0; 1;
2; 3; 4; 5 g/L. kcata fold 1.8 and 2.2 times corresponding to O3/M-
Dolomite process (4 g/L) and O3/FeMgO/CNT process (3.5 g/L)
compared with k obtained by ozone process.
COD removal efficiency after 60 minutes increased from 18 to
41.5%, corresponding to increasing the catalyst concentration from 0 to
3.5 g / L for O3/FeMgO/CNT process but only increased from 18 to
35% with O3/M-Dolomite process when increasing the catalyst
concentration from 0 - 5 g/L. Similar to COD, the efficiency of TOC
10
mineralization increased from 11 - 26.8% and 11