An up-to-date compilation of the theoretical background and practical procedures involved in lignin characterization. Whenever possible, the procedures are presented in sufficient detail to enable the reader to perform the analysis solely by following the step-by-step description. The advantages and limitations of individual methods are discussed and, more importantly, illustrated by typical analytical data in comparison to results obtained from other methods. This handbook serves the need of researchers and other professionals in academia, the pulp and paper industry as well as allied industries. It is equally useful for those with no previous experience in lignin or lignocellulosics.

Inhalt

1 Introduction.- 1 Introduction.- 1.1 General Structural Features of Lignin.- 1.2 Variations in Concentration and Composition of Lignin in Xylem.- 1.3 Isolation and Recovery of Lignin.- 1.4 Physical Properties of Lignin.- 1.5 Structure-Modifying Reactions.- 1.5.1 Modification of the Aromatic Ring.- 1.5.1.1 Electrophilic Substitution.- 1.5.1.2 Conversion of Aromatic Rings to Nonaromatic Cyclic Structures.- 1.5.1.3 Conversion of Cyclic to Acyclic Structures.- 1.5.1.4 Ring Coupling and Condensation Reactions.- 1.5.2 Modification of the Propanoid Side Chain.- 1.5.2.1 Cleavage of Ether Bonds.- 1.5.2.2 Cleavage of Carbon-Carbon Bonds.- 1.5.2.3 Substitution Reactions.- 1.5.2.4 Formation and Elimination of Multiple Bond Functionalities.- 1.5.3 Future Analytical Needs.- References.- 2 Detection and Determination.- 2.1 The Detection of Lignin.- 2.1.1 Introduction.- 2.1.2 Reagents for the Detection of Lignin.- 2.1.2.1 Aliphatic Compounds.- 2.1.2.2 Phenols and Aromatic Amines.- 2.1.2.3 Heterocyclic Compounds.- 2.1.2.4 Inorganic Reagents.- 2.1.2.5 Unclassified Reagents.- 2.1.3 Color-Forming Reaction Sequences.- 2.1.4 Procedures for the Detection of Lignin.- 2.1.4.1 Color Reaction with Phloroglucinol-Hydrochloric Acid.- 2.1.4.2 The Mäule Color Reaction.- 2.1.4.3 The Cross and Bevan Color Reaction.- 2.1.4.4 Color Reaction with Tosyl Chloride/Pyridine, p-Nitrosodimethylaniline/Potassium Cyanide.- 2.1.4.5 Color Reaction with Quinone Monochlorimide.- 2.1.4.6 Color Reaction with Potassium Nitrosodisulfonate.- 2.1.4.7 Color Reaction Based on the Formation of Nitrosophenols (Pearl-Benson Method).- References.- 2.2 The Determination of Lignin.- 2.2.1 Introduction.- 2.2.2 Direct Methods.- 2.2.2.1 Acid Hydrolysis of Wood and Pulp.- 2.2.2.2 Determination of Acid-Insoluble (Klason) Lignin in Wood and Pulp.- 2.2.2.3 Determination of Acid-Soluble Lignin in Wood and Pulp.- 2.2.2.4 Acid Hydrolysis of Annual Plants, Developing Wood, and Forage.- 2.2.2.5 Determination of Acid-Insoluble Lignin in Annual Plants, Developing Wood, and Forage.- 2.2.3 Indirect Methods.- 2.2.3.1 Spectrophotometric Methods.- 2.2.3.2 Determination of Lignin in Wood and Pulp by the Acetyl Bromide Method.- 2.2.3.3 Methods Based on Oxidant Consumption.- 2.2.3.4 Determination of the Kappa Number of Pulp.- 2.2.4 Determination of Lignin in Solution.- 2.2.4.1 Determination of Dissolved Lignin by the Modified Pearl-Benson (Nitrosation) Method.- References.- 3 Isolation and Purification.- 3.1 Wood.- 3.1.1 Introduction.- 3.1.2 Preferred Method for Isolation and Purification of Lignin.- 3.1.2.1 Isolation.- 3.1.2.2 Purification.- 3.1.3 Discussion.- 3.1.3.1 Modifications of and Comments on the Preferred Method.- 3.1.3.2 Milled Wood Lignin as a Representative of the Lignin in Wood.- 3.1.3.3 Milled Wood Lignin Compared with Brauns Lignin.- 3.1.3.4 Milled Wood Lignin Compared with Cellulolytic Enzyme Lignin.- References.- 3.2 Isolation of Lignin from Pulp.- 3.2.1 Introduction.- 3.2.2 Procedures.- 3.2.2.1 Preparation of Pulp Samples and Enzyme Solution.- 3.2.2.2 Isolation of Residual Lignins in Unbleached Pulps.- 3.2.2.3 Isolation of Residual Lignins from Semi-Bleached Pulps.- 3.2.2.4 Purification of the Residual Lignins.- 3.2.3 Concluding Remarks.- References.- 3.3 Commercial Spent Pulping Liquors.- 3.3.1 Introduction.- 3.3.2 Principle.- 3.3.2.1 Kraft (Sulfate) Lignin.- 3.3.2.2 Lignosulfonate (Sulfite Lignin).- 3.3.3 Methods.- 3.3.3.1 Isolation Procedure for Kraft Lignin.- 3.3.3.2 Isolation Procedure for Lignosulfonates.- 3.3.4 Composition of Isolated Lignin.- 3.3.4.1 Kraft Lignin Fractions.- 3.3.4.2 Lignosulfonate Fractions.- 3.3.5 Discussion.- References.- 4 Characterization in Solid State.- 4.1 Fourier Transform Infrared Spectroscopy.- 4.1.1 Principles and Instrumental Techniques.- 4.1.1.1 Introduction.- 4.1.1.2 Scope of FTIR Spectroscopic Applications.- 4.1.1.3 Description of a Standard FTIR Instrument.- 4.1.1.4 Advantages of FTIR Spectroscopy.- 4.1.2 Method.- 4.1.2.1 FTIR Spectroscopy in Practice.- 4.1.2.2 Procedures.- 4.1.3 Lignin Characterization in the Mid-Infrared Region (4000?500 cm?1).- 4.1.3.1 Band Assignment and Classification of Lignin IR Spectra.- 4.1.3.2 Influence of Carbonyl Groups.- 4.1.3.3 Mathematical Resolution of Spectra.- 4.1.3.4 Effect of Acetylation.- 4.1.3.5 Quantitative Evaluation.- 4.1.4 Lignin Spectra in the Near-Infrared Region (4000?10000 cm?1).- 4.1.5 Lignin Spectra in the Far-Infrared Region (50?500 cm?1).- 4.1.6 Concluding Remarks.- References.- 4.2 Ultraviolet Microscopy.- 4.2.1 Introduction.- 4.2.2 Information Obtained by UV Microscopy.- 4.2.2.1 Photomicrographs.- 4.2.2.2 Lignin Concentration.- 4.2.2.3 UV Absorption Spectra.- 4.2.3 Experimental Methods.- 4.2.3.1 Specimen Preparation.- 4.2.3.2 Photography.- 4.2.3.3 Quantitative Analysis.- 4.2.4 Concluding Remarks.- References.- 4.3 Interference Microscopy.- 4.3.1 Introduction.- 4.3.2 Principle.- 4.3.3 Method.- 4.3.3.1 Specimen Preparation.- 4.3.3.2 Measurement of Refractive Index.- 4.3.3.3 Calculation of Lignin Concentration from Refractive Index.- 4.3.3.4 Measurement of Porosity.- 4.3.3.5 Calculation of Lignin Concentration from Porosity.- 4.3.4 Discussion.- 4.3.4.1 Comparison with Other Techniques.- 4.3.4.2 Types of Specimen that Can be Examined.- 4.3.4.3 Accuracy and Precision.- References.- 4.4 Electron Microscopy.- 4.4.1 Introduction.- 4.4.2 Principles.- 4.4.2.1 Glossary.- 4.4.2.2 Principles of SEM-EDXA and TEM-EDXA.- 4.4.3 Methods.- 4.4.3.1 Specimen Thickness.- 4.4.3.2 Procedure for Bromination-EDXA.- 4.4.4 Lignin Distribution in Cell Walls.- 4.4.4.1 Softwoods.- 4.4.4.2 Hardwoods.- 4.4.4.2.1 Distribution of Lignin.- 4.4.4.2.2 Distribution of Guaiacyl and Syringyl Lignins.- 4.4.5 Comparisons of Bromination-EDXA with Other Methods.- References.- 4.5 Cross Polarization/Magic Angle Spinning Nuclear Magnetic Resonance (CP/MAS NMR) Spectroscopy.- 4.5.1 Introduction.- 4.5.2 Principle of CP/MAS NMR.- 4.5.2.1 Cross Polarization.- 4.5.2.2 Magic Angle Spinning.- 4.5.3 Description of Methods for CP/MAS NMR Spectroscopy.- 4.5.3.1 Choice of Spectrometer.- 4.5.3.2 Sample Preparation.- 4.5.3.3 Determination of Lignin in Wood and Pulp.- 4.5.3.4 Interrupted Decoupling.- 4.5.3.5 Estimation of Syringyl/Guaiacyl Ratios.- 4.5.3.6 Estimation of the Degree of Etherification.- 4.5.3.7 Resolution Enhancement.- 4.5.4 Discussion.- 4.5.5 Future Developments.- References.- 4.6 Raman Spectroscopy.- 4.6.1 Introduction.- 4.6.2 Principle.- 4.6.3 Method.- 4.6.3.1 Raman System.- 4.6.3.2 Scattering Geometries.- 4.6.3.3 Specimens and Sampling.- 4.6.4 Spectral Information.- 4.6.4.1 Identification of Native Lignin Features.- 4.6.4.2 Quantitative Analysis of Lignin in Wood.- 4.6.4.3 Orientation and Composition Studies of Lignin in Woody Tissue.- 4.6.5 Discussion.- 4.6.5.1 Comparison with Other Techniques.- 4.6.5.2 Future Development.- References.- 4.7 Pyrolysis-Gas Chromatography-Mass Spectrometry.- 4.7.1 Introduction.- 4.7.2 Principle and Methods of Analytical Pyrolysis.- 4.7.2.1 Combination of Pyrolysis with Other Instruments.- 4.7.2.2 Pyrolysis Techniques.- 4.7.2.2.1 Induction Heating (Curie-Point Pyrolysis).- 4.7.2.2.2 Resistance Heating.- 4.7.2.3 Sample Preparation, Size, Geometry, and Contamination: General Considerations.- 4.7.3 Gas Chromatography.- 4.7.3.1 Op…