Summary of doctoral thesis: Study to determine the content of some chlorbenzen compounds from unintentional emission sources in industrial zones in Thai Nguyen province

Research objectives of the thesis: Study the process of simultaneous determination and evaluation of the method of analyzing 7 chlorobenzene, including 1,2- 4 dichlorobenzene (1,2-DCB); 1,3-dichlorobenzene (1,3-DCB); 1,2,4- trichlorobenzene (1,2,4-TCB); 1,2,3,4-tetrachlorbenzene (1,2,3,4- TeCB), 1,2,4,5-tetraclobenzene (1,2,4,5-TeCB); pentaclobenzene (PeCB) and hexaclobenzene (HCB) in trace and superficial content in flue gas samples and industrial waste (fly ash, bottom ash, input materials).

GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY

- *** -

STUDY TO DETERMINE THE CONTENT OF SOME

CHLORBENZEN COMPOUNDS FROM UNINTENTIONAL

EMISSION SOURCES IN INDUSTRIAL ZONES IN THAI

NGUYEN PROVINCE

Major: Analyticalchemistry Code: 9.44.01.18

SUMMARY OF DOCTORAL THESIS

Ha Noi, 2019

This thesis is completed at: Vietnam Academy of Science and

Technology

Scientific instructors:

Assoc Dr TU BINH MINH

Assoc Dr NGUYEN THI HUE

Thesis reviewer 1: Prof Dr

Thesis reviewer 2: Assoc Dr

Thesis reviewer 3: Assoc Dr

The thesis will be presented to the scientific council at the Vietnam Academy of Science and Technology at … h, date … , month … , year

2019

INTRODUCTION

1 The urgency of the thesis

Research on the pollution of persistent organic compounds (POPs) has been receiving the attention of many scientists all around the world The assessment of pollution levels and emissions of dioxin-like chlorobenzene compounds such as hexaclobenzene (HCB), Pentaclobenzene (PeCB), tetrachlorene (TeCB), triclobenzene (TCB), diclobenzene (DCB) is the scientific basis for countries Participating

in signing the Stockholm Convention to implement the plans for management, disposal and environmental pollution treatment by POPs well In Vietnam, the focus is mainly on studying U-POPs such as dioxin, furans and PCBs in soil, sediment, organisms and human Disclosures related to unintentional emissions of chlorbenzen compounds into the environment from industrial manufacture and waste disposal in Vietnam are limited

From above problems, it is necessary to research into the overall sources of emissions and the level of environmental pollution caused by the sources of industrial waste of chlorbenzenes, optimizing the efficiency of the process analysis in accordance with conditions in Vietnam This is a topical issue in current conditions when health and environment in Vietnam are at an alarming level Therefore, I decided

to choose the topic "Study to determine the content of some chlorbenzen compounds from unintentional emission sources in industrial zones in Thai Nguyen province", contributing to the protection and sustainable development of ecological environment in Thai Nguyen province

2 Research objectives of the thesis

- Study the process of simultaneous determination and evaluation of the method of analyzing 7 chlorobenzene, including 1,2-

dichlorobenzene (1,2-DCB); 1,3-dichlorobenzene (1,3-DCB); trichlorobenzene (1,2,4-TCB); 1,2,3,4-tetrachlorbenzene (1,2,3,4-TeCB), 1,2,4,5-tetraclobenzene (1,2,4,5-TeCB); pentaclobenzene (PeCB) and hexaclobenzene (HCB) in trace and superficial content in flue gas samples and industrial waste (fly ash, bottom ash, input materials)

1,2,4 Adopting an optimal procedure to simultaneously identify chlorobenzene in industrial samples including waste gas, ash, materials of some industrial fields in industrial zones in Thai Nguyen province

- Preliminary assessment of the level and emission characteristics of chlorobenzene from the thermal process of a number of industrial fields including waste incinerators, metallurgy, brick production and cement production

3 The main research contents of the thesis

- Study the process of simultaneous determination and evaluation of the method of analyzing 7 chlorobenzene

+ Survey and select optimal conditions to analyse chlorbenzen compounds on gas chromatography equipment using electronic resonance detector (GC-ECD) and mass spectrometry (GC-MS)

+ Investigate optimization of processing samples including extraction, cleaning and enrichment

+ Verification of analytical methods: determination of linear range, calibration curve, detection limit and quantitative limit, recovery coefficient and repeatability of the method

- Apply the optimal procedure to simultaneously identify chlorbenzenes in industrial samples

+ Analysis of the content of chlorbenzenes in gas samples and solid samples taken from factories in Thai Nguyen province and some northern provinces on GC-ECD equipment and confirm the presence

of above chlorinated benzene compounds GC-MS

+ Evaluation of homogeneous characteristics is the ratio of the content of each substance to the total content of chlorobenzene, in the types of industrial waste gases and solid waste samples

+ Evaluation of emission factors is to find out annual emissions and the risk of chlorobenzene on humans from a number of industries in Thai Nguyen province

4 New contributions of the thesis

1 Optimized conditions to simultaneously identify 7 clobezen targets, in industrial samples (waste gas samples and waste solid samples (Fly ash, bottom ash) in trace amounts and super stains using GC-ECD and GC-MS

2 Successfully developed the process of analyzing chlorbenzen compounds in trace amounts and super stains

3 The first step was to identify and determine the emission level through the emission factor and the annual emission of 7 chlorbenzenes from industrial solid waste samples in Thai Nguyen province

This is the first published study in Vietnam on unintentional emission levels of chlorbenzenes in some industries Thereby contributing to the control of emissions to limit and completely eliminate hazardous POPs in the environment, meeting the requirements of the Stockholm Convention, towards sustainable development in Vietnam

CHAPTER 1: OVERVIEW OF RESEARCH PROBLEMS 1.1 OVERVIEW OF THE RESEARCH SUBJECT

1.1.1 Overview of Chlorobenzens

Derivatives of chlorbenzenes C6H (6-x) Clx form a stable and colorless group with a pleasant odor Chlorine can be substituted for six hydrogen atoms on benzene rings to be able to form twelve different chlorinate compounds including: Monoclobenzene (MCB); ortho-diclobenzene (1,2-DCB); meta-diclobenzene (1,3-DCB), para-diclobenzene (1,4-DCB); 1,2,3-triclobenzene, 1,2,4-triclobenzene; 1,3,5-triclobenzene; 1,2,3,4-tetraclobenzene; 1,3,4,5-tetraclobenzene; 1,2,4,5-tetraclobenzene; Pentaclobenzene; Hexaclobenzene The physical and chemical properties of clobenzene (CBz) compounds when they are released into the environment, are likely to evaporate into the atmosphere The atmospheric CBz will be decomposed primarily through reactions with hydroxyl radicals to produce nitroclobenzene, clophenol, and fatty dicarbonyl products, which continue to be removed by photochemistry or reaction with hydroxyl radicals CBz compounds released into water will accumulate in suspended solids and sediments (especially rich organic sediments) All CBz are easily absorbed by humans and animals through the digestive and respiratory pathways.The absorption is affected by the position and number of chlorine in chlorobenzene congeners After absorption, chlorbenzenes quickly distribute to organs, accumulate mainly in adipose tissue and can remain there for a long time, in small amounts in the liver and other organs

1.1.2 the formation of chlorbenzen compound from some

industrial activities

An incomplete destruction of burned materials in which CBz

is available CBz Formed by the metabolism of compounds is precursor or formed in low temperature areas from carbon particles and chlorine compounds - synthesized denovo However, the CBz emission content during combustion depends very much on the

combusting conditions and the presence or absence of catalytic materials CBz can also be formed due to the chlorination process of HCB (Figure 1.1) in the presence of catalysts such as Cu, CuO, High / a-Fe2O3 metal ) to create copper lower chlorine CBs

1.2 DOMESTIC AND OVERSEAS STUDY SITUATION

1.2.1 Studies in the world

In recent years, a number of studies have also focused on unintentional POPs emissions from the production of non-ferrous metals and ferrous metals, iron ore production of iron and steel, coke production and other secondary color metallurgy process A research

in China in the industry of zinc and lead metals production in 2007 showed that the average emission factor of PCDD / Fs in gas samples for lead and zinc manufacturing industry is 98.2 and 0.35, respectively

ng TEQ / (Nm3); in fly ash samples is 5.64 ng TEQ / g with zinc industry; 0.05 ng TEQ / g in lead manufacturing industry Emission factors of gas samples for PCBs from zinc and lead production are respectively 2,786 and 0,002 ng TEQ / Nm3.The formation and reduction of emissions of clobenzene, polychlorinated dibenzo-p-dioxin and dibenzofurans polychlorinated (PCDD / Fs) have been studied in a typical dry cement kiln in China Emissions of PCDD / F and CBz in emissions are 0.16 ng I-TEQ Nm-3 and 26 µg / Nm3 respectively The concentration of 1,2-DCB ranges from 100 - 9424

ng / Nm3; 1.3 and 1.4 –DCBz are 223 - 6409 ng / Nm3 1,3,5 / 1,2,4 / 1,2,3- TCB in the range of 35 - 3542 ng / Nm3 (of which 1.2, 4 accounts for the largest amount); 1,2,3,5-TeCB & 1,2,4,5-TeCB range between 2 - 491 ng / Nm3, while isomer 1,2,3,4-TeCB is 6 - 562 ng / Nm3 ; Concentrations PeCB and HCB range from 1 to 335 ng / Nm3 and 1 to 128 ng / Nm3 respectively

1.2.2 Domestic studies in Vietnam

Studies on POPs compounds such as dioxin / furan, DDT, PCBs in Vietnam have been of interest since the end of the 20th century because of their toxicity and changes in awareness in

environmental protection of managers as well as scientists However,

in Vietnam, the focus is only on studying POPs in environmental objects of soil, sediment, organisms and people to overcome the consequences of chemical toxins / dioxin No claims have been made regarding the assessment of the emissions of chlorbenzen compounds (DCB, TCB, TeCB, PeCB, HCB) unintentionally emissions in many industrial production and recycling industries So the assessment and comparison of pollution levels and emission sources for this group of

substances face many difficulties

CHAPTER 2: EXPERIMENT AND RESEARCH METHOD 2.1 SCOPE AND SUBJECTS OF RESEARCH

The research object of the thesis is 7 chlorbenzen targets of 5 isomers, including dichlorobenzene (1,2; 1,3 - DCB); trichlorobenzene (1,2,4-TCB); tetraclobenzene (1,2,3,4; 1,2,4,5-TeCB); Pentaclobenzene (PeCB) and hexaclobezen (HCB)

* Industrial factories and incinerators in Thai Nguyen province are listed in table 2.1

* Industrial production plants and incinerators in Northern provinces

of Vietnam collected for comparison with samples collected from Thai Nguyen

Table 2 1 Information about actual samples

g

Factor

y sign

Type of productio

n

Capacit

y (ton / h)

Emissio

n rate (Nm3 / h)

Averag

e capacit

y / year THÁI NGUYÊN

2.2.5.1 Sampling, shipping and preservation methods

2.2.5.2 Sampling and actual sample information

2.2.5.3 Method of CBz analysis on GC-ECD equipment

2.2.5.4 Study the sample processing process and confirm the use value of the method

2.2.5.5 Analysis of real samples

2.2.5.6 Evaluation of emission levels and assessment of the risk of chlorbenzen compounds

2.3 PROCESS OF ANALYSIS

Figure 2.1 Process of analyzing CBz in solid samples

Figure 2.2 Process of analyzing CBz in gas sample

CHAPTER 3: RESULTS AND DISCUSSION

3.1 SURVEY THE OPTIMIZED CONDITIONS FOR ANALYSIS OF CBZ TIMES ON GAS ACCESSORIES

3.1.1 Investigate optimal conditions with CBz standard solution on GC-ECD equipment

3.1.1.1 Column temperature program

According to the results, it was found that the increase of high temperature from 120oC – 150oC was not suitable, so the thesis selected the temperature of 70o C as the initial temperature then gradually increased the temperature to 120oC in 2 minutes, the separation of substances with more reasonable retention time CBz results show that at a low heating rate of 5 ° C / min long analysis time (more than 30 minutes) causes time to analyze as well as other factors High heating speed of 20° C / min causes peaks to be eluted quickly, thus resulting in peak duplication At a heating speed of 10°C / min, it’s good for peak separation and reasonable analysis time (about 20 minutes) Therefore, choosing a heating speed of 10° C / min for further studies After investigating the optimal conditions when analyzing CBz with GC-ECD, the parameters are listed in Table 3.1

Table 3.1 Excellent parameters when analyzing CBz on

GC-ECD 2010 device

Pump port temperature 220 ° C

Air flow mode Pressure

Column head pressure 100 kPa

Volumetric suction

sample

1 µl

Line split rate 1:10

program

Pressure Flow rate through

column

1 ml / minute Separation column SPB-608 (30 m × 0.25 mm × 0.25 µm)

Column oven temperature program

70 oC

70 oC to 120oC Heating speed 10° C / min; hold 2

120 oC to 280oC Heating speed 10° C / min; hold for 5

minutes Total analysis timephân

tích

18minutes Detector Temperature 300 °C

3.1.1.2 Sample pump conditions

Results of analysis on GC-ECD showed that when using split mode, the peak has a special tail-pulling phenomenon at peak 1 and 2, which affects the process of determining the area of peak used for quantification The thesis chooses split-line mode to analyze CBz

non-on GC-ECD equipment At low current cnon-onditinon-ons of 1: 5, peaks tend

to move toward the solvent peak 1: 20 high current split conditions for low signal PeCB, HCB signal, increase the influence of baseline during analysis Therefore, the thesis uses the ratio of 1:10 for the peaks of the CBz signals and is used in the next survey conditions The result of retention time of CBz is shown in Table 3.2

Table 3.2 Retention time of CBz standard solutions on

3.1.2.1 Stability of analytical signals

Calculated results of research CBz for repeated injections of standard solution at low concentration C1 and high concentration C2 have RSD values varying from 1.27% to 15.0% (<20%) which shows repeatability of good analytical signals, high stability

3.1.2.2 Qualitative limit (LOD) and quantitative limit (LOQ) of the device

The analytic results obtained the LOD value of the gas chromatograph for the study CBz ranging from 0.94 to 1.46 ppb and LOQ value from 3.14 to 4.87 ppb This is a concentration with good detectional sensitivity and a relatively stable peak signal

3.1.3 Determine the linear range of the calibration curve of CBz on GC-ECD device

The calibration curves of substances has regression coeffiction R2

greater than 0,99

3.1.4 Analysis of CBz on GC / MS equipment

3.1.4.1 Optimal condition for CBz analysis on GC / MS equipment

Table 3.3 Optimal parameters when

( 1: 1,3-DCB; 2: 1,2- DCB; 3: 1,2,4 - TCB; 4: 1,2,4,5 - TeCB;5: 1,2,3,4 – TeCB;

6: PeCB; 7: HCB;8: PeCNB)