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.
Trang 1MINISTRY 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
Trang 2Technology – Vietnam Academy of Science and Technology
Scientific Supervisor 1: PGS.TS Trinh Van Tuyen
Scientific Supervisor 2: PGS.TS Lê Truong Giang
Hanoi, Vietnam at…hour…date…month…in 2019
The thesis can be found at:
- Vietnam National library
- Library of the Graduate University of Science and Technology
Trang 3PUBLISHED 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
Trang 47 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)
Trang 5INTRODUCTION
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)
Trang 6are 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
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
Trang 7New 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 O/FeMgO/CNT process
Trang 82.3.1.6 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
Trang 9complex 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 O 3 on material surfaces
Fig 3.1: Dissolved O 3
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
Trang 10there 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
Trang 11concentration 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
k increase gradually from 0.0122 - 0.0312 (1/min) in O /M-Dolomite
Trang 12process 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
Trang 133.3.2 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 Fe2+, Fe3+ 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
Trang 14mineralization increased from 11 - 26.8% and 11 - 23.5% corresponding
to the O3/FeMgO/CNT and O3/M-Dolomite processes The value of COD, TOC at the concentration of 3.5 g/L FeMgO/CNT respectively decreased from 0.96 g/L and 0.3 g/L before treatment decreased to 0.66 g/L and 0.24 g/L after 60 minutes after treatment
Fig 3.12: Effect of catalyst
concentration on removal
efficiency of phenol
Fig 3.13: Effect of catalyst concentration on apparent constant rate of phenol decomposition
The concentration of 3 g/L of FeMgO/CNT and 4 g/L Dolomite catalyst was selected as the optimal concentration for further studies in the phenol treatment by heterogeneous catalytic ozonation processes
M-3.3.3 Influence of stirring speed on phenol treatment efficiency
The results show the removal efficiency of phenol, COD, TOC and apparent rate constants of phenol decomposition tend to increase as the speed of stirring increases
Phenol decomposition efficiency increased from 42.3% to 56.3% when increasing the stirring speed from 150-300 rpm when treating phenol by ozone process but the influence is not significantly increased when the stirring speed increased from 200 to 300 rpm
Fig 3.15: Influence of speed
stirring to removal efficiency of
phenol with and without catalyst
Fig 3.16: Influence of speed stirring to
apparent reaction rate constants of phenol
removal with and without catalyst