Nghiên cứu tổng hợp vật liệu khung cơ kim fe MOFs, ứng dụng làm xúc tác quang để xử lý một số hợp chất nitro vòng thơm trong sản xuất thuốc phóng thuốc nổ tt tiếng anh

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF NATIONAL DEFENCE ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY TRAN DINH TUAN STUDY ON SYNTHESIS OF THE METAL ORGANIC FRAMEWORKS Fe-MOFs MAT

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF NATIONAL DEFENCE

ACADEMY OF MILITARY SCIENCE AND TECHNOLOGY

TRAN DINH TUAN

STUDY ON SYNTHESIS OF THE METAL ORGANIC FRAMEWORKS Fe-MOFs MATERIALS AND USED AS PHOTOCATALYST FOR TREATMENT OF AROMATIC NITRO

COMPOUNDS IN EXPLOSIVES PRODUCTION

Specialization: Chemical engineering

Code: 952 03 01

SUMMARY OF DOCTORAL THESIS

Hanoi - 2019

Academy of Military Science and Technology, Ministry of Defence

Scientific supervisors:

Assoc Prof Dr Ninh Duc Ha

Dr Do Huy Thanh

Reviewer 1: Prof Dr Vu Thi Thu Ha

Reviewer 2: Assoc Prof Dr Cao Hai Thuong

Reviewer 3: Assoc Prof Dr Tran Van Chung

The thesis was defended in front of the Doctoral Evaluating Council at Academy level held at Academy of Military Science and Technology at 8:30 AM, date … month … , 2019

The thesis can be found at:

- The Library of Academy of Military Science and Technology

- Vietnam National Library

1 Tran Dinh Tuan, Ninh Duc Ha, Nguyen Thi Hoai Phuong, Nguyen

Cong Thang (2015), “Synthesis and study reactive photocatalysis of

Fe-BDC and Cr-BDC”, Vietnam Journal of Chemistry, No.53(5e1),

p.43-47

2 Tran Dinh Tuan, Le Thanh Bac, Ninh Duc Ha, Do Huy Thanh

(2015), “Study on synthesis of MIL-100(Fe) at low temperature and

atmospheric pressure”, Vietnam Journal of Chemistry, No.53(6e4),

p.322-325

3 Le Thanh Bac, Tran Dinh Tuan, Nguyen Thi Hoai Phuong,

Nguyen Duy Anh, Tran Van Chinh, Doan Thi Ngai (2015), “Study synthesis on material metal organic framework based on Fe-BDC”,

Vietnam Journal of Chemistry, No.53(4e1), p.33-36

4 Tran Dinh Tuan, Nguyen Thi Hoai Phuong, Ngo Hoang Giang,

Nguyen Tien Hue, Do Huy Thanh, Ninh Duc Ha (2016), “Study on synthesis of Fe-BTC MOF material at low temperature and

atmospheric pressure” Proceedings CASEAN-4, Bangkok,

Thailand

5 Tran Dinh Tuan, Nguyen Thi Hoai Phuong, Do Huy Thanh, Ninh

Duc Ha (2016), “Synthesis and reactive photocatalysis of MOF material based on Fe-BTC”, Vietnam Journal of Catalysis and Adsorption, No.2, 91-96

6 Tran Dinh Tuan, Le Viet Ha, Nguyen Thi Hoai Phuong, Ninh Duc

Ha (2017), “A new photocatalyst for the degredation of TNT by metal organic framework NH2-MIL-88B(Fe)” Journal of Military

Science and Technology, Special Issue, No.51A, 71-76

INTRODUCTION

1 The urgency of the thesis topic

In Vietnam, defense industry factories produce a large amount of explosives for military and civil purposes every year This industry uses

a range of aromatic nitro derivatives such as trinitro toluene (TNT), dinitro toluene (DNT), trinitro phenol (TNP) which results in a large amount of waste containing toxic aromatic compounds Meanwhile, the present technologies for handling military waste in general and aromatic ring nitro compounds in particular still exist many limitations Many catalysts have been used for treatment of aromatic ring nitro compounds Among them, the photocatalysis materials based on semiconductors such as TiO2, ZnO… are well-known which have proven their high effectiveness for degradation of toxic organic waste However, the disadvantagies such as the poor recyclibility, low light harvesting efficiency, fast charge recombination have limited their application in practical

Metal-organic frameworks materials (MOFs) are known as hybrid inorganic-organic material, which metal-oxide units or metal ions joined

by organic linkers through strong covalent bonds MOFs have unique crystal structure, large specific surface area, flexible structural frame, resizable size, porosity through synthetic methods Therefore, MOFs can be employed as best candidate for adsorption and catalysts application Many domestic and international scientists had been studied

on the field of MOFs materials for few decade It must be emphasized that MOFs are very potential materials More research is needed to contribute to the database of the MOFs material synthesis and catalysis applications, especially as photocatalyst for environmental treatment

In order to fulfill this task, the PhD student has proposed and implemented the thesis topic: "Study on synthesis of the metal organic frameworks Fe-MOFs materials and used as photocatalyst for treatment

of aromatic nitro compounds in explosives production", with the aim is

to contribute to the diversification of MOFs material synthesis techniques, characterize and evaluation of prepared materials and their potential application as photocatalyst for the degradation of toxic aromatic nitro waste in explosive production

2 The contents

- Study on the synthesis of Fe-BTC and Fe-BDC-NH2 by the refluxing method at low pressure and temperature

- Study on the synthesis of Fe-BDC and Fe2Ni-BDC by the solvothermal method

- Analyzing structure and characterization of synthesized materials

- Investigate photocatalytic activity of the Fe-MOFs materials for degradation of TNT, TNP solutions in lab scale

- Study on the mechanism of the photocatalytic behavior toward the TNT, TNP solutions of Fe-MOFs materials

3 The research method

The thesis used the solvothermal and the refluxing methods at low temperature to synthesize Fe-MOFs materials Modern physical and chemical analysis techniques are used to structure analysis and characterizration of synthesized materials such as: XRD, FT-IR, SEM, BET, TGA, EDX, XPS, UV-Vis DRS Furthermore, the qualitative and quantitative analysis techniques for content of TNT, TNP in the solutions after degradation reactions such as HPLC, TOC are also employed to determine photocatalysis treatment effectiveness

4 Scientific significance and applicability of the thesis

- Synthesis of several Fe-MOFs materials by solvothermal and refluxing methods and using physical and chemical analyzing techniques to contribute to the database of the materials

- Study on the application of synthesized materials as the photocatalyst to removal of TNT, TNP out of wastewater in the explosive industry The results show that four synthesized materials have high efficiency and degradation rate The results of the thesis are primary for application of Fe-MOFs materials for treatment of wastewater containing nitro aromatic ring compounds

5 The layout of thesis

The thesis contains 119 pages which is constructed as following: Overview 3 pages; chapter 1 - Introduction, 31 pages; chapter 2 - Experiments, 18 pages; chapter 3 - Results and Dicussion, 50 pages; Conclusion 3 pages; List of published scientific reports, 1 page and 106 references

Chapter 1 Introduction

Overview about structural properties, synthesis methods and application of MOFs as well as Fe-MOFs materials Analysis and evaluation of research status on the application of photocatalytic properties and photocatalytic degradation mechanism of MOFs materials in Vietnam and around the world Overview about status of solutions for the removal of aromatic nitro compounds out of

wastewater in propellant and explosive manufacture industry As a result, establishscientific basis and orientation for implementing of the research content of the thesis

Chapter 2 Experiments 2.1 Synthesis method

2.1.1 Materials

Terephthalic acid (H2BDC), C8H6O4; Trimesic acid (H3BTC),

C9H6O6; 2-Amino terephthalic acid (NH2-BDC), C8H7NO4; FeCl3.6H2O; Fe(NO3)3.9H2O; Ni(NO3)2.6H2O; Dimethyl formamide (DMF),

C3H7NO; Hydro peroxide, H2O2; Trinitro toluene, C6H2(CH3)(NO2)3; Trinitro phenol, C6H2(OH)(NO2)3

2.1.2 Accessories and equpipments

- Basic laboratorial accessories

- 250 mL three - neck flask, gauge glass, reflux condenser

- Analytic balance, measure range from 0,001 to 220 g

- Mechanical stirrer with glass stirrer, IKA RW16, Germany

- 200 mL Autoclave reactor 304 stainless with PTFE liner

- Heating oven, 101 HU VUE, China

- Centrifugal machine, EBA 21 Hettich, Germany, maximum speed

6000 rpm

- Heating plate and magnetic stirrer, IKA C-MAGSH, Germany

- Photocatalytic reactor

2.1.3 Synthesis of Fe-BTC

2.1.3.1 Synthesis process of Fe-BTC

Fe-BTC was synthesized by refluxing method Typically, mixture of Fe(NO3).9H2O and acid H3BTC were dissolved in 50.4 mL distilled water and magnetic stirred for 30 minutes After that, the solution was poured into the three-neck flask and adjusted pH about 6 and stirred in

15 minutes The refluxing condenser system was installed, magnetic stirring speed was adjusted about 300 rpm The system was heated to

100oC and and maintained for 8 hours The product was washed many times by distilled water to remove impurities and washed by ethanol at

70oC Finally, the product was filtered and heated at 60oC for 10 hours

2.1.3.2 Study on the effect of factors on the synthesis

Study on the effect of factors on the synthesis of Fe-BTC such as: percentage of reactants, reaction time, reaction temperature by adjusting mol ratio of H3BTC/Fe3+ from 0.5:2 to 2:2; reation time is 4, 6,

8, 10 hours; reaction temperature is 60, 80, 100oC

2.1.4 Synthesis of Fe-BDC-NH 2

Fe-BDC-NH2 was synthesized by refluxing method Typically, the mixture of FeCl3.6H2O and DMF were dissolved in glass cup, magnetic stirred for 30 minutes, added NH2-BDC acid and stirred continually for

15 minutes After that, the solution was poured into the three-neck flask and adjusted pH about 6 and stirred for 15 minutes The refluxing condenser system was installed, magnetic stirring speed was adjusted about 300 rpm The system was heated to 100oC and and maintained for

8 hours The product was washed many times by DMF to remove acid and washed by ethanol at 70oC to remove DMF Finally, the product was filtered and heated at 60oC for 10 hours

Study on the effect of factors on the synthesis of Fe-BDC-NH2

such as: percentage of reactants, reaction time, reaction temperature

by adjustment mol ratio of NH2-BDC/Fe3+ from 0.5:1 to 2:1; reation time is 4, 6, 8, 10 hours; reaction temperature is 60, 80, 100oC

2.1.5 Synthesis of Fe-BDC, Fe 2 Ni-BDC

2.1.5.1 Synthesis technique of Fe-BDC

Fe-BDC was synthesized by solvothermal method Typically, a mixture of FeCl3.6H2O, H2BDC and DMF were dissolved with mol ratio

of which were 1:1:280, respectively A mixture of FeCl3.6H2O and 160

mL DMF were dissolved and then added gently 1.235 g H2BDC acid in the solution and stirred continually until the solution was transmisparent, yellow and pH of which was 6 After that, the solution was poured into autoclave reactor and heated at 110oC for 10 hours The product was washed 2 times by DMF and washed 2 times by ethanol at

70oC Finally, the product was filtered and heated at 60oC for 5 hours and maintained in vacuum condition

Fe2Ni-BDC was synthesized by solvothermal method Typically, prepared a mixture of [FeCl3.6H2O + Ni(NO3)2.6H2O] and H2BDC and DMF with mol ratio were 1:1:280, respectively and mol ratio of FeCl3.6H2O/Ni(NO3)2.6H2O were 2:1 The mixture of FeCl3.6H2O, Ni(NO3)2.6H2O and 160 mL DMF were dissolved and then added gently 1.235 g H2BDC acid in the solution and strirred continually until the solution was transmisparent, yellow and pH=6 After that, the solution was poured into autocalve reactor and heated at 110oC in 10 hours The product was washed 2 times by DMF at room temperature and washed 2

times by ethanol at 70oC Finally, the product was filtered, heated at

60oC for 5 hours and maintained in vacuum condition

2.2 Photocatalytic degradation of TNT/TNP solutions using

Fe-MOFs materials

Photocatalytic degradation tests were carried out by dispersion of MOFs materials in TNT/TNP solutions, the reacted solution were poured into a 250 mL glass beaker and magnetic stirred with speed of

300 rpm, the period temperature were controlled at room temperature, under simulated sunlight conditions (Philips LED lights, 40 W power,

1200 lux intensity, 440-415 nm wavelength, 4 - 6% UV light)

Experiments were performed with 100 mL of TNT / TNP solutions, Fe-MOFs catalytic dosage were 0.5 g / L, adding 0.4 mL of 30% H2O2

solution (0.05 M) for reaction times of 15, 30, 45, 60 minutes, after each period time took 2 mL of sample, filted and analyzed HPLC, TOC to determine the concentration of TNT / TNP Determination of adsorption characteristics of synthesized materials was carried out the same in the dark condition

2.2.1 Study on the effect of factors on photocatalyst degradation TNT solution using Fe-BDC-NH 2 materials

Study on the effect of factors such as: content of catalyst, luminous intensity, initial concentration of TNT solution, pH, temperature and content of additive H2O2

2.2.2 Study on recyclability of catalytic materials

The photocatalytic experiments were repeated several times with

100 mL of TNT solution of 50 mg/L, with pH = 7, a catalyst content of 0.5 g/L, adding 0.4 mL of 30% H2O2 solution Photocatalytic reactions were performed at room temperature and take samples for analysis every 60 minutes For the second, third and fourth experiments, the solution was regenerated and calculated to add a content of TNT so that concentration of TNT in solution is 50 ppm

2.3 Analysis techniques for investidation of photocatalytic activity

2.3.1 Analysis technique to characterization

The modern physical and chemical analysis techniques were used to analyze and evaluate properties synthesized material consist of XRD, FT-IR, SEM, TGA, BET, EDX, XPS, UV-Vis-DRS

2.3.2 Analysis technique to evaluate treated wastewater samples

The efficiency of photocatalytic degradation was determined by using HPLC and TOC technique

Chapter 3 RESULT AND DICUSSION

3.1 Synthesis of Fe-BTC

3.1.1 Study on the effect of some factors on the synthesis of Fe-BTC material

Fe-BTC materials were synthesized for 8 hours, at 100oC, with mol ratio of H3BTC/Fe3+ in turn are: 0.5:2; 1:2; 1.5:2; 2:2 Synthesized reaction equation is followed:

Fe(NO3)3.9H2O + H3BTC → Fe3O(H2O)2(OH)(BTC)2.nH2O + H2O + HNO3

XRD patterns in Figure 3.1 showed that sample M1.1-2 had peaks

of Fe-BTC with high intensity, and position of the peaks at 2θ = 6.03o; 6.6o; 10.59o, 11.12o were similar to XRD patterns of MIL-100 in previous works, thus synthesized Fe-BTC material was MIL-100(Fe) When mol ratio of H3BTC/Fe3+ was 0.5:1 (M2.0,5-1 sample), acid concentration was not enough to form crystalline structure of Fe-BTC material XRD patterns of the samples with high molar ratio of

H3BTC/Fe3+ (M1.1,5-2, M1.2-2) had low intensity of specific peaks, simultaneously the presence of other peaks were ascribed to diffracted peaks of H3BTC acid M1.1-2 sample was considerred as the most similar to MIL-100(Fe) reported previously Therefore, the H3BTC/Fe3+molar ratio of 1:2 was chosen as optimized ratio to synthesize Fe-BTC material

Figure 3.1 XRD patterns of synthesized Fe-BTC material with the

different molar ratios of H3BTC/Fe3+

3.1.1.2 Effect of temperature on the MOF formation

Formation of Fe-BTC materials was investigated at various temperatures such as 60oC, 80oC and 100oC The reaction time of the

refluxing process was 8 hours and the molar ratio of H3BTC/ Fe(NO3)3.9H2O/H2O was 1:2:280

The synthesized Fe-BTC materials is investigated by XRD analysis with 2θ from 5 to 35o XRD patterns showed that the materials have similar structure reported previously without any byproduct All investigated materials had the specific peaks at same positions The material synthesized at 80oC revealed the highest crystalline intensity peaks The result was in consistent with published reports

3.1.1.3 Effect of reaction time on MOF synthesis

Fe-BTC materials reaction were caried out for different period of time such as 4; 6; 8 and 10 hours The temperature of reaction was held

at 80oC and the mol ratio of H3BTC/ Fe(NO3)3.9H2O/ H2O was 1:2:280 The synthesized Fe-BTC materials were investigated by XRD analysis with 2θ from 5 to 35o XRD patterns showed that the materials had similar structure without presence of byproduct All investigated materials had the specific peaks at same positions The material obtained with 8h of reaction time revealed the highest crystalline intensity peaks The result is consistent with published reports

XRD patterns in 3.4 showed that M1-4h sample had the lowest intensity specific peaks, while M1-8h and M1-10h have the highest intensity peaks No impurity peaks were observed in all samples Therefore, the reaction time of 8 hours was chosen as optimal reation time The result is similar to published reports

Figure 3.4 XRD patterns of synthesized Fe-BTC with various reaction

time

3.1.2 Synthesizing procedure of Fe-BTC

Based on the investigations of the influencing factors on the MOFs synthesis as well as selection of optimal reaction condition, synthesized

procedure of Fe-BTC material in lab scale by refluxing method with

H3BTC: Fe(NO3)3.9H2O: H2O molar ratio of 1:2:280 was established as following:

A mixture of 4.07 g Fe(NO3)3.9H2O and 1.05 g H3BTC was dissolved in 50.4 mL distilled water The solution was homogenised on magnetic stirred for 30 minutes and then poured into three neck flask and sitrred for 15 minutes The refluxing condenser system was installed, magnetic stirring speed was adjusted about 300 rpm The system was heated to 80oC and maintained for 8 hours The product was washed three times by distilled water and washed three times by ethanol

at 70oC Finally, the product was filtered and heated at 60oC for 10 hours Obtained Fe-BTC material is pink, the yield of the synthesis process was 66,8%

Figure 3.5 Diagram of synthesis procedure of Fe-BTC material

3.1.3 Characteristic of synthesized Fe-BTC material

Structural investigation of synthesized Fe-BTC material was analyzed as follow:

XRD pattern of synthesized Fe-BTC material showed in Figure 3.6 and indicated that the presence of peaks at 2θ = 5.3o; 6.03o; 6.6o; 10.59o; 11.12o; 20.15o; 27.79o In which the peaks at 2θ = 6.03o; 6.6o; 10.59o; 11.12o were specific peaks of MIL-100(Fe) materials XRD pattern showed that the peaks were very sharp and high intensity which approved material had high crystalline This result was consistent with published results

Figure 3.6 XRD patterns of synthesized Fe-BTC material

IR spectrum of synthesized Fe-BTC material was showed in Figure 3.7 Several main vibrations included:

- The band at wave number 585 cm-1 corresponds to metal-O bond

- The strong band at 712 cm-1 corresponds to bending vibration of C-H bond in benzene ring

- The stronger band at 1382 represents C-O valence vibration in carboxyl group

- The present of the band at 1634 cm-1 results from the stretching vibration of C=C bond

- Finally, the other band at 3443 cm-1 corresponds to stretching vibration of O-H bond in H2O molecular in structure

Figure 3.7 FT-IR spectrum of synthesized Fe-BTC material

Figure 3.8 SEM image of synthesized Fe-BTC material

The crystals of synthesized Fe-BDC-NH2 material were in hexagonal shape with the average dimension of 0.5÷1 µm (Figure 3.8)

BET result of Fe-BTC material showed that surface area was 1777 m2/g, volume of porous hole was 0.85 cm3/g TGA result indicated that synthesized material was resisted the elevate temperature of 346oC

The materials were synthesized at 80oC for 8 hours, with molar ratios of NH2-BDC/Fe3+ were 0.5:1; 1:1; 1.5:1; 2:1 Reaction equation was showed as following:

FeCl3.6H2O + H2N-BDC → Fe3O(H2O)2(OH)(H2N-BDC)3.nH2O + HCl + H2O

Figure 3.11 XRD patterns of resultant Fe-BDC-NH2 compounds with

different molar ratios of NH2-BDC/Fe3+

Figure 3.11 show the XRD patterns of MOFs materials obtained with various molar ratios When molar ratio between NH2-BDC/Fe3+ is 0.5:1 (M2.0,5-1 sample), acid concentration was not enough to form crystalline structure of Fe-BDC-NH2 material, thus obtained product showed amorphous nature XRD patterns of the samples with high molar ratio of NH2-BDC/Fe3+ (M2.1,5-1, M2.2-1) had low intensity of specific peaks which characterize for Fe-BDC-NH2 material, moreover the presence of impurity peaks were characteristic difraction peaks of

NH2-BDC acid M2.1-1 sample with NH2-BDC/Fe3+ molar ratio 1:1 had specific peak of Fe-BDC-NH2 at 2θ = 9.12o; 9.74o; 18.90o with high intensity The result was consistent with previous reports Therefore, the