Lignin (eBook)

Preface 6
Contents 8
About the Editors 10
Lignin as Potent Industrial Biopolymer: An Introduction 12
1 Introduction 13
2 Sources and Structure of Lignin 13
2.1 Major Sources of Lignin 13
2.2 Structural Composition of Lignin 15
3 Lignin Extraction from Different Types of Biomass 16
3.1 Biological or Enzymatic Methods 16
3.2 Chemical Methods 17
3.3 Physical Methods 17
3.4 Miscellaneous Processes of Lignin Extraction and Conversion 18
4 Challenges in Lignin Conversion 18
5 Lignin-Derived Products of Industrial Importance 19
5.1 Lignin-Based Foams 19
5.2 Epoxy Resins from Lignins 20
5.3 Lignin-Based Ethers 20
5.4 Lignin-Based Esters 20
5.5 Lignin-Based Paints and Coatings 21
6 Conclusion 21
References 22
Structure and Characteristics of Lignin 27
1 Introduction 28
2 Structural Features of Lignin 31
2.1 Monolignols/Units 31
2.2 Inter-Unit Linkages 34
2.3 Lignin–Carbohydrate Complex (LCC) 37
2.4 Monolignol Radicals 38
2.5 Biosynthesis of Lignin 39
2.6 Computational Assays 42
2.7 Structural Models of Lignin 43
2.8 Classification of Lignins 45
3 Physicochemical Properties of Lignin 45
3.1 Heating Values 45
3.2 Molecular Weight and Polydispersity 45
3.3 Thermal Characterization 46
3.4 Solubility 47
3.5 Relative Density 48
3.6 Color 48
3.7 Functional Groups 48
3.8 Chemical Reactions 49
4 Depolymerization and Isolation Technologies 50
4.1 Brauns’ Lignin 50
4.2 Milled Wood Lignin (MWL) 51
4.3 Soda Lignin (Alkali Lignin) 51
4.4 Kraft Lignin 52
4.5 Sulfite Lignin (Lignosulfonates) 52
4.6 Organosolv Lignin 53
4.7 Klason Lignin 53
4.8 Hydrolytic Lignin 53
4.9 Acidolysis Lignin 54
4.10 Cellulolytic Enzyme Lignin (CEL) 54
4.11 Enzymatic Mild Acidolysis Lignin (EMAL) 54
4.12 Pyrolytic Lignin 55
4.13 Steam Explosion Lignin (SEL) 55
4.14 Ionic Liquid Extraction 55
4.15 Derivatization Followed by Reductive Cleavage (DFRC) 56
5 Instrumental Strategies 56
5.1 Elemental Analysis 57
5.2 Spectroscopic Methods 57
6 Summary and Prospects 69
References 71
Lignin Synthesis and Degradation 86
1 Introduction 86
2 Lignin Biosynthesis 88
2.1 Synthesis of Lignin Monomeric Units 88
2.2 Glycosylation of Monolignols Their Storage and Transport 94
2.3 Oxidative Polymerization 95
3 Lignin Degradation 95
3.1 Lignin-Modifying Enzymes 98
3.2 Supplementary Enzymes for Lignin Degradation (LDEs) 104
4 Way Forward 113
References 115
Analysis of Lignin Using Qualitative and Quantitative Methods 123
1 Introduction 123
1.1 Lignin 124
1.2 Biological Role and Commercial Significance 125
2 Lignin Analysis 127
2.1 Qualitative Methods of Lignin Analysis 128
2.2 Quantitative Methods of Lignin Analysis 133
2.3 Future Challenge and Development 140
3 Conclusion 141
References 142
Chemical Modification of Lignin by Polymerization and Depolymerization 147
1 Introduction 147
2 Lignin Polymerization 149
2.1 Methods for the Synthesis of New Reactive Sites in Lignin Structure 149
2.2 Modification of Lignin’s Hydroxyl Groups 154
2.3 Lignin-Based Polymers 159
3 Lignin Depolymerization 164
3.1 Depolymerization by Chemical Treatment 166
3.2 Depolymerization by the Thermochemical Process 170
3.3 Depolymerization by Biological Transformations 176
4 Conclusions 178
References 179
Lignin and Its Composites 189
1 Introduction 189
2 Lignin in Thermoplastic Composites 190
2.1 Polyethylene/Lignin Composites 190
2.2 Polypropylene/Lignin Composites 192
2.3 Polylactic Acid/Lignin Composites 195
3 Lignin in Thermoset Composites 198
3.1 Polyurethane/Lignin Composites 198
3.2 Epoxy/Lignin Composites 201
4 Conclusions 205
References 207
Advances in Nanotechnology based Strategies for Synthesis of Nanoparticles of Lignin 211
1 Introduction 212
2 Techniques for Synthesis of Micro- and Nanostructures of Lignin 215
2.1 Mechanical Processes 216
2.2 Solvent Shifting Method 217
2.3 pH Shifting Technique 217
2.4 Template-Based Synthesis Technique 218
2.5 Ice-Segregation-Induced Self-assembly Method 219
2.6 Aerosol Process 220
2.7 Electrospinning Method 220
2.8 Supercritical Fluid Processes 222
2.9 Solvent Antisolvent Precipitation 224
2.10 Acoustic Cavitation Assisted Nanoparticles Preparation 225
3 Conclusion and Future Prospective 226
References 228
Synthesis and Applications of Lignin-Derived Hydrogels 238
1 Introduction 239
2 Lignin as a Potential Material for Hydrogel Development 239
3 Synthetic Procedures for Lignin-Derived Hydrogels 240
3.1 Cross-Linking Method 241
3.2 ATRP and RAFT Methods 242
3.3 Copolymerization Method 242
3.4 Ultrasonication Method 242
3.5 Hydrothermal Method 243
3.6 Wet Spinning Method 243
4 Applications of Lignin-Derived Hydrogels 243
4.1 Therapeutic Agents 247
4.2 Adhesives 249
4.3 Adsorbents 250
4.4 Conductive Carbon Microfibers 252
4.5 Supercapacitors 252
4.6 Sustained Release Materials 253
4.7 Biosensors 254
4.8 Enzyme Immobilization 254
5 Conclusion 255
References 255
Lignin Composites for Biomedical Applications: Status, Challenges and Perspectives 260
1 Introduction 261
2 Prominent Properties of Lignin for Biomedical Applications 263
3 Biomedical Applications of Lignin Composites 264
3.1 Lignin Composites with Biological Activity 264
3.2 Lignin Composites for Wound Healing Applications 270
3.3 Lignin Composites for Tissue Engineering Applications 271
3.4 Lignin Composites for Drug Delivery Systems 274
4 Future Challenges and Perspectives 275
5 Conclusion 276
References 276
Applications of Lignin in the Agri-Food Industry 281
1 Introduction: Lignin-What Are They? 282
2 Lignin Structure, Derivatives, and Modifications 283
3 Established Uses of Lignin 286
4 Biological Activities and Therapeutic Potential 289
4.1 Antioxidant Activity 290
4.2 Antimicrobial Effects 292
4.3 Anticancer/Anti-tumor Activity 294
4.4 Anticoagulant, Anti-emphysema, Anti-diabetic, and Anti-obesity 294
5 Conclusion and Future Prospects 295
References 296