Isolation of lignin
Publisher Summary
This chapter presents some of the most useful methods for lignin isolation. The best known isolated lignin is probably Klason lignin, which is obtained by treating wood with sulfuric acid. The polysaccharides are hydrolyzed to water-soluble sugars, and the lignin is recovered as an insoluble residue. Although this method for lignin isolation has great utility as an analytical means of determining lignin content, the highly condensed and altered Klason lignin is generally unsuited for either chemical characterization or studies of biological modification and degradation. The most useful lignin preparation is Björkman lignin, also known as Björkman milled wood lignin or simply milled wood lignin (MWL). Milled wood lignin is purified from the aqueous p-dioxane extract of finely milled wood, which has been first extracted with organic solvents to remove extraneous components. Although it has not been rigorously proved that MWL is representative of protolignin, it is considered to be appropriate for most chemical and biological studies. The chapter discusses those procedures used to isolate lignin from wood.
References (16)
- K.-E. Eriksson et al.R.F.H. Dekker
- J.R. Obst
Tappi
(1982) - D. Fengel et al.
- A. Björkman
Sven. Papperstidn.
(1956) - K. Freudenberg et al.
Cited by (84)
Hydrothermal liquefaction of pinecone kraft lignin into selective phenolic: Optimization of Ni and Mo impregnation on ceria
2023, Journal of the Energy InstitutePine is an abundant forestry waste and is a main cause of forest fires in China's mountain area owing to its flammable nature. Therefore, its utilization for the production of valuable phenolics can contribute a small to fix it. This study examined Ni-impregnated ZrO2, CeO2, and MgO catalysts for hydrothermal liquefaction of pinecone lignin, which was extracted by applying the kraft process. The 5 wt%-Ni/CeO2 catalyst was found to be efficient with a 59.2 wt% bio-oil yield corresponding to 77.6% of total conversion in ethanol. This bio-oil yield was enhanced significantly to 65.7 wt% on applying the 3 wt% Mo along with 5Ni/CeO2. The effect of diverse solvents e.g., water, ethanol, methanol, IPA, and co-solvent mixture was also explored to achieve the greatest liquefaction of this PC kraft lignin. Amongst all, methanol/water (1:1) was highly compatible with the maximum liquefaction of kraft lignin (77.8%) at optimum 280 °C/30 reaction conditions. The GCMS analysis of optimum bio-oil attributes the higher selectivity of vanillin (67.4%) and validates the presence of guaiacyl sub-aromatic units in the lignin. The elemental analysis of cat-M-W bio-oil exhibits a considerable improvement in calorific value (38.4 MJ/kg) compared to that of raw lignin (28.1 MJ/kg). Additionally, the reusability test of the 5Ni–3Mo/CeO2 catalyst attributes the best performance of the catalyst up to two cycles without applying any kind of regeneration. Additionally, XRD and BET analysis of catalysts showed the impregnation of both metals (Ni & Mo) at the CeO2 surface in the oxide form.
The effects of lignin source and extraction on the composition and properties of biorefined depolymerization products
2023, RSC SustainabilityWe explore the efficacy of depolymerization as a function of lignin source and extraction method under the conditions of our previously described biorefinery. Biomass source (i.e. herbaceous, softwood, and hardwood) influences the total available lignin and structural features such as the ratio of monomers (S/G) and the percentage of β-O-4 linkage. The method of extraction (i.e. Milled Wood (mild), Organosolv (medium), and Klason (harsh)) determines levels of solubilization, preservation of the intrinsic lignin structure, and distribution and properties of products. Herbaceous lignin extracted by the Organosolv process is best suited for depolymerization in our biorefinery and shows the greatest extent of solubilization (∼100% over 7 days), the highest yields of phenolics and flavonoids, and the most and smallest lignin nanoparticles. Additionally, this depolymerized product mixture has the highest antioxidant capacity. Only the harsh, Klason method successfully isolates lignin, through carbohydrate conversion, from all three sources, but the herbaceous and hardwood sources are depolymerized to a lesser extent than by the Organosolv method. With low density of labile bonds, softwood lignin is not effectively depolymerized under these conditions. Although modifying intrinsic lignin structure the least, Milled Wood lignin does not efficiently extract lignin from any of the biomass, and the extracted lignin is low in purity inhibiting further processing. These results further detail the promise of herbaceous Organosolv lignin as a renewable feedstock to high value products in a distributed-scale biorefinery.
Transforming lignin into renewable fuels, chemicals, and materials: A review
2023, Bioresource Technology ReportsLignin, Lignin is a valuable carbon-rich feedstock and a by-product of the lignocellulosic biorefinery and paper industry. Despite being widely available, it is an under-utilized material. Lignin is the second most prevalent biopolymer with a polyaromatic structure present in the cell wall of vascular plants. However, its complex molecular structure and selective solubility in some solvents make its commercial feasibility largely unexplored. In recent decades, lignin has gained attention as a renewable raw biomaterial for synthesizing industrially important value-added materials such as adhesives, resins, foams, lubricants, composites, and high-value chemicals. Despite this, a significant portion of lignin produced in the pulp and paper mill ends up as boiler fuel for power and heat production. The production of lignin from different methods and sources is often compared and questioned due to handling and environmental issues resulting from excessive production. This review paper discusses the structure of lignin, its types, extraction methods, modification via thermal and chemical approaches, applications, prospects, and challenges.
Wide distribution of extracellular electron transfer functionality in natural proteinaceous organic materials for microbial reductive dehalogenation
2023, Journal of Bioscience and BioengineeringExtracellular electron transfer materials (EETMs) in the environment, such as humic substances and biochar, are formed from the humification/heating of natural organic materials. However, the distribution of extracellular electron transfer (EET) functionality in fresh natural organic materials has not yet been explored. In the present study, we reveal the wide distribution of EET functionality in proteinaceous materials for the first time using an anaerobic pentachlorophenol dechlorinating consortium, whose activity depends on EETM. Out of 11 natural organic materials and 13 reference compounds, seven proteinaceous organic materials (albumin, beef, milk, pork, soybean, yolk, and bovine serum albumin) functioned as EETMs. Carbohydrates and lipids did not function as EETMs. Comparative spectroscopic analyses suggested that a β-sheet secondary structure was essential for proteins to function as EETMs, regardless of water solubility. A high content of reduced sulfur was potentially involved in EET functionality. Although proteinaceous materials have thus far been considered simply as nutrients, the wide distribution of EET functionality in these materials provides new insights into their impact on biogeochemical cycles. In addition, structural information on EET functionality can provide a scientific basis for the development of eco-friendly EETMs.
Functional naturally derived materials to improve the environment: Chemical structures, modifications, applications, and future perspectives
2023, Advances in BioenergyNaturally derived polymers have recently gained interest worldwide due to concerns about increasing greenhouse gas emissions and depletion of fossil resources. Naturally derived polymers, such as polysaccharides, protein, lipids, fatty acids, and lignin, are produced from renewable resources and abundant in nature, and provide a negative carbon footprint. Naturally derived polymers have played a pivotal role in producing high-performance functional materials in environmental applications. However, the use of naturally derived polymers is largely limited by their cost of collection and separation, hydrophilicity, and mechanical properties. New modification and functionalization methods are urgently needed to satisfy the versatile market needs on material properties and performance. Thus, this chapter reviews (1) the types of naturally derived materials and their molecular structures; (2) various modification and functionalization methods; and (3) their applications in wastewater remediation, environmental sensors, food safety, and smart fertilizers. Finally, we address the existing barriers and challenges faced by bio-based materials and their future perspectives.
Pectin-associated mannans and xylans play distinct roles in cell-cell adhesion in pine and poplar wood
2022, Industrial Crops and ProductsWood particles of pine required longer treatments of acidic chlorite and dilute alkali to achieve similar proportions of cell separation as of poplar. Chemical extraction and enzymatic digestion studies indicated that rhamnogalacturonan-I (RG-I), mannan and xylan contribute to cell-cell adhesion in pine wood. Mannan associated with lignin in an acidic chlorite fraction and with xylan in a dilute alkali fraction. RG-I and xylan were extracted in both chlorite and dilute alkali in poplar. Scanning electron microscopy and a probe diffusion study using Fluorescence Recovery After Photobleaching showed that lignin, RG-I and mannan initiated cell separation at cell corners and dilute alkali extraction of xylan was required for complete cell separation in pine. Cell-cell separation increased enzymatic saccharification within 24 h by 2-fold in poplar and 3.4-fold in pine. Our results inform a strategy to reduce particle size in woody biomass and provide insights into different molecular bases of cell-cell adhesion.