Lignin isolation and characterization as co-products from pilot plants of second generations bioethanol (original) (raw)
Related papers
Extraction and Characterization of Lignin from Different Biomass Resources
Lignocellulosic biomass has been acknowledged for potential use to produce chemicals and biomaterials. Lignin is the second most abundant natural polymer with cellulose being number one, making up to 10–25% of lignocellulosic biomass. Lignin is a three-dimensional, highly cross-linked macromolecule composed of three types of substituted phenols, which include: coniferyl, sinapyl, and p-coumaryl alcohols by enzymatic polymerization, yielding a vast number of functional groups and linkages. There is a wide range of lignin sources available, including: jute, hemp, cotton, and wood pulp. Hence, the lignin’s physical and chemical behavior will be different with respect to the original source and extraction method used. The objective of this research is to extract lignin from nonwood cellulosic biomass (Wheat straw, Pine straw, Alfalfa, Kenaf, and Flax fiber) by formic acid treatment followed by peroxyformic acid treatment for the potential use as a partial replacement for the phenol precursor in resole phenolic systems. Isolated lignins were purified to remove impurities and characterized by Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) analysis to compare thermal properties and chemical composition. It was found that lignin obtained from alfalfa provided the greatest yield of the various sources. Enthalpy measurements were higher for lignin from flax fiber and alfalfa at 190.57 and 160.90 J/g, respectively. The source of lignin samples was seen to affect the thermal properties. Overall, lignin extracted from wheat straw had the greatest thermal stability followed very closely by that obtained from flax fiber.
The potential of organosolv and kraft eucalyptus and spruce lignin as feedstock for polymeric materials and biofuel applications was assessed. Proximate analysis was used to predict the heating values and char formation. Chemical modification, based on the esterification reaction with methacryloyl chloride, was applied to introduce vinyl groups into the lignin macromolecules for enhanced reactivity. Kraft eucalyptus and spruce lignins had a more condensed structure than organosolv lignins, which resulted in greater thermal stability for these lignins. For different species within the same process, the thermal parameters showed a correlation with certain structural and compositional parameters (ash and sugars content, molecular weight and degree of condensation). Organosolv spruce lignin produced the highest heating value of 24 MJ/Kg, which is suitable for biofuel applications. The content of phenolic OH groups was higher for kraft lignins and especially higher for softwood lignins, both organosolv and kraft. The degree of methacrylation, estimated from the content of vinyl groups per C9 lignin unit, was significantly greater for organosolv lignins than for kraft lignins despite the higher OH-groups content in the latter.
Lignin is the most abundant natural source of renewable aromatic units and therefore, detail characteri-sation to unveil its chemical properties is a critical step for its utilisation. Nine black liquor samples from different plant origins namely sugarcane bagasse, Eucalyptus grandis, and Pinus gregii extracted from the Kraft, soda, soda-anthraquinone and sulphite pulping processes were considered. After lignin purification, when applicable, the samples were characterised by several common methods (wet chemical methods, Fourier Transformed Infra-Red spectroscopy, Gel Permeation Chromatography). Lignin monomer composition (H:G:S) was determined by thioacidolysis as well as a new pyrolysis method based on the use of an analytical setup which couples Thermo Gravimetric Analysis (TGA) for lignin devolatilisation, the capture of released volatile compounds in thermal desorption (TD) tubes, and the quantification of the captured phenols by TD-GC–MS (gas chromatography–mass spectroscopy). The TGA-TD-GC–MS, with the use of internal calibration, allowed the quantification of 5.5–12.9 wt.% of monomeric products based on dry weight of purified lignin. Pyrolysis of sugarcane lignin resulted in significant yield of furfural, which was explained by the conversion of residual sugar. Pyrolysis of pine lignin gave the lowest yield of syringyl-type phenols, which was consistent with characterisation results (low methoxy content and absence of FT-IR band characteristic of syringyl unit). Pyrolysis method had the advantage to break different types of chemical bonds, which is likely to give a product distribution more representative of the lignin. With TGA-TD-GC–MS the monomer proportion for purified lignin from the same plant species were found to be very comparable (deviation lower than 10% for each unit). Compared to thioacidolysis (known to be selective towards bond cleavage and suspected to overestimate S content), TGA-TD-GC–MS gave lower S/G ratio. The TGA-TD-GC–MS method has demonstrated to be a good alternative technique to study the H:G:S proportions of lignins with low ash content (<5%).
Bioresources
Corn stover and rice straw lignin samples received from ethanol pilot plants, along with softwood kraft lignin samples, were characterized using pyrolysis GC-MS, 13 C CP/MAS NMR spectroscopy, and permanganate oxidation degradation. The lignins were then esterified using 1-methylimidazole as a catalyst in a pyridine-free reaction, and the thermal properties of the products were evaluated. Solid state NMR showed the rice straw lignin contained 18% residual polysaccharides. Pyrolysis GC-MS showed the softwood kraft, corn stover, and rice straw lignins to be G-type, H/G/S-type, and G/S-type, respectively. However, some discrepancy was apparent between the pyrolysis and permanganate oxidation studies as to the ratios of the monomeric makeup of the lignins. The kraft and rice straw lignins were determined to have high degrees of condensation, while the corn stover lignin was uncondensed. Little to no increase in solubility was noticed for corn stover or rice straw lignin esters in organic solvents. Glass transition temperatures (T g) of the lignin derivatives were determined by a combination of differential scanning calorimetry, dynamic mechanical analysis, and parallel plate rheometry.
Characterization of Lignins Isolated from Industrial Residues and their Beneficial Uses
BioResources, 2016
The physico-chemical properties of lignin isolated from lignocellulosic bioethanol residues and hardwood kraft black liquor were compared with two commercial lignins, kraft softwood lignin, and soda non-wood lignin. Lignin from the industrial residues was isolated through the acid precipitation method. The amount of lignin isolated was approximately 38% of the dry weight of lignocellulosic bioethanol residues and approximately 27% of the black liquor solids. The numbers of methoxyl groups and phenolic and aliphatic hydroxyls were determined to derive a molecular formula for each of the four lignins. The molecular weights of the lignins were measured by high performance size exclusion chromatography. Potential value-added applications of the lignins were summarized based on their molecular weights and physico-chemical characteristics.
Review Engineering Plant Biomass Lignin Content and Composition for
2015
Lignin is an aromatic biopolymer involved in providing structural support to plant cell walls. Compared to the other cell wall polymers, i.e., cellulose and hemicelluloses, lignin has been considered a hindrance in cellulosic bioethanol production due to the complexity involved in its separation from other polymers of various biomass feedstocks. Nevertheless, lignin is a potential source of valuable aromatic chemical compounds and upgradable building blocks. Though the biosynthetic pathway of lignin has been elucidated in great detail, the random nature of the polymerization (free radical coupling) process poses challenges for its depolymerization into valuable bioproducts. The absence of specific methodologies for lignin degradation represents an important opportunity for research and development. This review highlights research development in lignin biosynthesis, lignin genetic engineering and different biological and chemical means of depolymerization used to convert lignin into biofuels and bioproducts.
A concise review of current lignin production, applications, products and their environmental impact
Industrial Crops and Products, 2019
Lignin is the second most abundant natural material on the earth. Commercially, it is generated as a waste product from the paper and ethanol production. The worldwide production of lignin is approximately 100 million tonnes/year valued at USD 732.7 million in 2015. It is expected to reach $913.1 million by 2025 with compound annual growth rate (CAGR) of 2.2%. Two principal categories of lignin are ligno-sulphonate (˜88%) and kraft lignins (˜9%), however a new category organosolv (˜2%) is now gaining popularity due to the production of second generation biofuels (bioethanol production). The organosolv lignin segment is expected to experience the highest growth over the coming years, at an estimated CAGR of over 5% from 2016 to 2025. Chemically lignin is a polyaromatic macromolecule. The complexity and richness of its functional groups makes it attractive for converting into a variety of value added products like high performance carbon fiber, bio-oil, vanillin, and phenolic resin to name a few. Over the years lignin has been predominantly burnt as fuel for heat and power. Less than 2% of the available lignin was sold, primarily in the formulation of dispersants, adhesives and surfactants. However, in the last decade lignin-based research and new product development has picked significant momentum due to the bio-refinery concept as aging pulp and paper mills need to diversify their products portfolio to maintain their vitality. The emerging biofuel/bioenergy technologies are working to develop value-added co-products from lignin and bio-oil as a means of making the processes more cost effective. There is a resurgence in the demand for lignin for use in binders, adhesives, bioplastics, concrete admixtures and biomedical applications. Effective "upstream" and "downstream" valorization techniques are facilitating fine tuning of lignin as a building block for high value chemicals. Other market dynamics driving lignin use are stringent regulations for dust control, demand for high quality concrete admixtures and dispersants, and carbon rich products (activated carbon, carbon filer, resins etc.). To further accelerate development of lignin based products consumer awareness and gap between research and development and consumer products need to be reduced. Despite the growing body of research on the possibilities of
Lignin as co-product of second generation bioethanol production from ligno-cellulosic biomass
2014
To improve the economic viability of the biofuel production from biomass, it is of increasing importance to add value to the lignin produced as a bio-residue. Moreover, to meet the goal to replace 30% of fossil fuel by biofuels by 2030, a huge amount of lignin will soon be produced. The first major step involved to add value to the unconverted lignin is its separation from other biomass constituents to give high purity lignin. In this current work, extraction of lignin from a bio-residue (containing ca. 40% lignin) from second generation bioethanol production is presented. The biomass chosen is Arundo donax L. (or giant reed), which is non-food plant, can tolerate a wide variety of ecological conditions with all types of soils, and has increasingly importance as raw material for industrial purposes as a source of fibers alternative to wood, which availability is decreasing. Slightly different extraction procedures are investigated. Methods used are simple, mild, safe, and avoid destruction of fiber content in the bioresidue, with the final aim to valorize all fractions of the bio-residue, which is an essential step to make biofuel production to be cost effective. Lignins extracted are characterized by morphological analysis, using Scanning Electron Microscopy, SEM, and in terms of thermal behavior-using thermo gravimetric analysis TGA-which is critical for determining suitability of the lignin for polymer composite preparation with improved thermomechanical performance. The method judged as the best of the three leads rapidly to extraction of lignin free from fibers and ash, with thermal behavior suitable for composite preparation.