Title Page

Abstract

Contents

CHAPTER 1. Introduction 14

1.1. Ionic liquids and deep eutectic solvents 15

1.2. Bioactive compounds 27

1.3. Biofuel 31

1.4. Biomass 33

1.5. Purpose of this thesis 34

CHAPTER 2. Experimental 35

2.1. Chemicals 36

2.1.1. Bioactive compounds 36

2.1.2. Biofuel 37

2.2. Instruments 38

2.2.1. Bioactive compounds 38

2.2.2. Biofuel 39

2.3. Methods 39

2.3.1. Application of eco-friendly solvents in bioactive compounds 39

2.3.1.1. Extraction of flavonoids 39

2.3.1.2. Headspace single-drop microextraction (HS-SME) of terpenoids 44

2.3.1.3. Adsorption of lactic acid and ferulic acid 45

2.3.1.4. Size exclusion chromatography for separation of polysaccharides 50

2.3.2. Application of eco-friendly solvents in biofuel 52

2.3.2.1. Adsorption of ethanol from bioethanol fuel 52

2.3.2.2. Preparation and separation of biodiesel 57

CHAPTER 3. Results and Discussions 59

3.1. Bioactive compounds 60

3.1.1. Eco-friendly solvents as additives in extractions 60

3.1.1.1. Extraction of flavonoids by ILs 60

3.1.1.2. Headspace single-drop microextraction of terpenoids by DESs 72

3.1.2. Eco-friendly solvents modified materials as separation media 78

3.1.2.1. Adsorption of lactic acid by ionic liquids based polymers 78

3.1.2.2. Adsorption of ferulic acid by deep eutectic solvents based silica 90

3.1.2.3 Separation of polysaccharides by DESs based size exclusion chromatography 97

3.2. Biofuel 108

3.2.1. ILs based polymers as separation media to bioethanlol 108

3.2.2. DESs as catalysts in preparation of biodiesel 123

Conclusions 130

Summary in Korean 132

References 133

Appendix 6

1. Dehydration of ethanol by facile synthesized glucose-based silica 144

2. Using linear solvation energy relationship model to study the retention factor of solute in liquid chromatography 145

3. Development of gas chromatography analysis of fatty acids in marine organisms 146

4. Optimized analytical conditions of eicosapentaenoic and docosahexaenoic acids in Antarctic Krill using gas chromatography 147

5. Zinc ion doped solid-phase extraction of eicosapentaenoic acid and docosahexaenoic acid from Antarctic Krill 148

List of publication 149

Table 1-1. Application of ILs for extraction and separation. 17

Table 1-2. ILs based silica.(표없음) 8

Table 1-3. Preparation of IL based polymer. 23

Table 2-1. 1-methylimidazole series ILs in this study. 40

Table 2-2. BBD with the independent factors and corresponding responses. 43

Table 2-3. Abbreviation of the ChCl-EG based DESs studied. 44

Table 2-4. Ammonium fluoride-based DESs examined in this studied. 50

Table 2-5. Ethanol concentrations in eight fermentation broth. 54

Table 2-6. Compositions of the synthesized deep eutectic solvents (DESs). 57

Table 3-1. Analysis of the BBD in terms of the factors and corresponding responses for the extraction of dihydrokaempferol, quercitrin, amentotlavone and myricetin. 67

Table 3-2. Parameters of analytical performance of the proposed method. 77

Table 3-3. Effect of the initial lactic acid concentration on the adsorption of lactic acid. 85

Table 3-4. Effect of pH on the adsorption of lactic acid. 87

Table 3-5. Element and structure analysis of ClChCl-Urea modified silica, and three isotherms parameters of adsorption. 92

Table 3-6. BET data of the DES-based silica spheres. 99

Table 3-7. Data of the three DES-based silica spheres fitted by three adsorption equations. 106

Table 3-8. Recycle adsorption on poly([1-vinyl-3-hexylimidazolium] [Tf₂N]). 123

Table 3-9. Intra-day and inter-day precisions, accuracies and recoveries of palmitic acid with three different concentrations. 129

Fig. 1-1. Some HBD and HBA counterparts that can be combined to form a DES. 26

Fig. 2-1. Preparation scheme of the ionic liquid-modified porous polymer. 46

Fig. 2-2. (a) Preparation of ClChCl-Urea DES. (b) Synthesis of DES-based silica. (c) Ion exchange mechanism between ClChCl-Urea modified silica and ferulic acid. 49

Fig. 2-3. Schematic flow diagram of the experimental procedure. 53

Fig. 3-1. Effect of conventional methods and solvents on the amount of flavonoids extracted from CO leaves. 61

Fig. 3-2. Comparison of the extractions based on [EMIM][Br] as an additive with no additives on the amount of flavonoids extracted from CO leaves. 62

Fig. 3-3. Effect of the chain length of the 1-MIM series ILs cations on the amount of flavonoids extracted from CO leaves. 64

Fig. 3-4. Effect of anions on the amount of flavonoids extracted from CO leaves. 65

Fig. 3-5. Effects of factors, X₁, X₂ and X₃ on R₁, R₂, R₃ and R₄ shown in RSM. 71

Fig. 3-6. Concentrations of the three terpenoids (a) in the different solvents of HS-SME. 73

Fig. 3-7. Concentrations of the three terpenoids by HS-SME at different temperatures in DES-3. 74

Fig. 3-8. Concentrations of the three terpenoids by HS-SME for different time. 75

Fig. 3-9. Concentrations of the three terpenoids in HS-SME at different sample/DES-3 ratios. 77

Fig. 3-10. Comparison of HS-SME, ultrasonic extraction and heat flux extraction of the three terpenoids from CO. 78

Fig. 3-11. FT-IR spectra of all ionic liquid-modified porous polymers. 79

Fig. 3-12. SEM images of PIM (A), PMIM (B) and PEIM (C). 79

Fig. 3-13. Adsorption kinetics curves of lactic acid at an initial lactic acid concentration of 10 ㎎/mL and 20 ℃ 82

Fig. 3-14. Adsorption kinetics curves of lactic acid at an initial lactic acid concentration of 10 ㎎/mL and at different temperatures. 82

Fig. 3-15. Effect of the amount of adsorbents on the adsorption of lactic acid. 84

Fig. 3-16. Langmuir isotherm model for lactic acid adsorption on PIM, PMIM and PEIM. 88

Fig. 3-17. Freundlich isotherm model for lactic acid adsorption on PIM, PMIM and PEIM. 89

Fig. 3-18. Temkion isotherm model for lactic acid adsorption on PIM, PMIM and PEIM. 89

Fig. 3-19. FT-IR spectra of DES-modified silica. 92

Fig. 3-20. (a) Nitrogen adsorption-desorption isotherms. (b) Pore volume distributions in the nitrogen adsorption-desorption process. (c) Pore area distributions in the nitrogen adsorption-desorption process. 93

Fig. 3-21. Effects of time and adsorbent amount on the adsorption. 96

Fig. 3-22. Effects of the initial concentration on the adsorption. 96

Fig. 3-23. Low-magnification SEM images of the mesoporous silica sphere based DES-1 (a), DES-2 (b) and DES-3 (c). 99

Fig. 3-24. (a) Isotherm, pore volume distribution and pore area distribution of the mesoporous silica sphere-based DES-1 in the nitrogen adsorption-desorption process. 100

Fig. 3-24. (b) Isotherm, pore volume distribution and pore area distribution of the mesoporous silica sphere-based DES-2 in the nitrogen adsorption-desorption process. 101

Fig. 3-24. (c) Isotherm, pore volume distribution and pore area distribution of the mesoporous silica sphere-based DES-3 in the nitrogen adsorption-desorption process. 101

Fig. 3-25. Molecular structures of the three macromolecules. 102

Fig. 3-26. (a) Amounts of alginic acid adsorbed on the three DESs modified silica spheres. 103

Fig. 3-26. (b) Amounts of fucoidan adsorbed on the three DESs modified silica spheres. 104

Fig. 3-26. (c) Amounts of laminarin adsorbed on the three DESs modified silica spheres. 104

Fig. 3-27. Separation of the alginic acid, fucoidan and laminarin standards by the three HP-SEC columns 107

Fig. 3-28. FTIR spectra of poly([VHIM][Tf₂N]). 108

Fig. 3-29. (a) Effect of the initial bio-ethanol concentration on the poly([VHIM][Tf₂N]) adsorption kinetics and equilibrium. 111

Fig. 3-29. (b) Effect of temperature on the poly([VHIM][Tf₂N]) adsorption kinetics and equilibrium. 113

Fig. 3-29. (c) Effect of the poly([VHIM][Tf₂N]) dose on the adsorption kinetics and equilibrium. 115

Fig. 3-30. (a) Langmuir isotherm for bio-ethanol adsorption. 117

Fig. 3-30. (b) Freundlich isotherm for bio-ethanol adsorption. 117

Fig. 3-30. (c) Temkin isotherm for bio-ethanol adsorption. 118

Fig. 3-31. Separation factors of ethanol/water, ethanol/glucose and ethanol/xylose obtained with poly([VHIM][Tf₂N]). 119

Fig. 3-32. Comparison of bio-ethanol adsorbed on poly([VHIM][Tf₂N]) and activated carbon. 120

Fig. 3-33. Recovery and purity of bio-ethanol in the desorption solution. 122

Fig. 3-34. Effect of the Brønsted–Lowry acid-based DESs (DESs/methanol ratio: 1 wt%, Methanol/palmitic acid: 0.5㎎/mL (1mL), temperature: 60℃, time: 60 min). 124

Fig. 3-35. Effect of the DESs/methanol ratio (Methanol/palmitic acid: 0.5㎎/mL (1mL), temperature: 60℃, time: 60 min). 125

Fig. 3-36. Effect of the reaction temperature (Methanol/palmitic acid: 0.5㎎/mL (1mL), DES/methanol ratio: 10 wt%, time: 60 min). 126

Fig. 3-37. Effect of the reaction time (Methanol/palmitic acid: 0.5㎎/mL (1mL), DES/methanol ratio: 10 wt%, temperature: 80 ℃). 127

Fig. 3-38. Effect of the methanol/palmitic acid ratio (DES/methanol ratio: 10 wt%, temperature: 80 ℃, time: 120 min). 128

Scheme 3-1. Disassociation equilibrium of lactic acid in solution. 85

Scheme 3-2. Proposed scheme for the anion exchange mechanism on porous polymers. 86

Scheme 3-3. Synthesis of DES-based silica. 91

Scheme 3-4. Ion exchange mechanism between ClChCl-Urea modified silica and ferulic acid. 94

 In recent years, because of the development of green chemistry, eco-friendly solvents such as, ionic liquids (ILs) and deep eutectic solvents (DESs), have accelerated research in chemistry areas. ILs and DESs are widely recognized green solvents owing to their excellent properties, such as poor highly viscous, low vapor pressure, low combustibility, excellent thermal stability, wide liquid regions and favorable solvating properties for a range of polar and non-polar compounds. Bioactive compounds from plants have attracted significant research interest because of their direct effects on living organisms depending on the substance, dose or bioavailability. Therefore, the extraction and separation of large bioactive compounds in plants using eco-friendly solvents based technologies is beneficial to the development of medicine and human health, and is necessary for further development. In addition, biofuel as a sustainable fuel has been derived from many plants and could become a instead of fossil fuel. However, biofuel is inappropriate to be directly applied as a row material feed for a fuel, so the purification of biofuel from row materials is a major issue associated with its production. Although recent development of traditional separation technology, has improved the separation efficiency, the development has some issues such as, the high energy consumption, the complex operation, the environmental pollution, and so on. Therefore, a simple and eco-friendly separation of biofuel is explored in this study. To duel with the above issues, this thesis is systematically organized and introduced according to my research work.