Isolation Of Lignin Research Articles

Process for Treating Spent Liquor of the TMP Process with Biomass-Based Fly Ash

The spent liquor (SL) of the thermomechanical pulping (TMP) process has a high effluent load. In this work, biomass-based fly ash was used for adsorbing lignin of SL and thus for reducing the COD and turbidity of SL prior to sending SL to a wastewater treatment system. By treating SL with fly ash in a one-stage adsorption process under the conditions of a fly ash/SL ratio of 55 mg/g and 3 h at 30 °C, 67 mg/g of lignin was adsorbed on fly ash at room temperature. Adjusting the pH of SL had an insignificant influence on the lignin isolation from the system but affected the turbidity of SL. The lignin removal was 68% in a two-stage fly ash adsorption process, while the COD and turbidity removal were 70% and 94%, respectively. On the basis of the results, a process for reducing the effluent load of SL using fly ash was proposed.

Isolation and Structural Characterization of Lignin from Cardoon (Cynara cardunculus L.) Stalks

The lignin from Cynara cardunculus stalks was isolated by the classical Bjorkman method and characterized by pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS), two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR), and derivatization followed by reductive cleavage (DFRC). The milled Cynara lignin (MCyL) was constituted mainly by guaiacyl (G) and syringyl-units(S) (S/G molar ratio of 0.7), with the complete absence of p-hydroxyphenyl (H) units. The 2D-NMR analysis indicated a predominance of alkyl-aryl ether linkages (70 % of all inter unit linkages are β–O–4′) and significant amounts of condensed structures such as phenylcoumarans (β-5′, 14 %), resinols (β-β′, 7 %), spirodienones (β-1′, 5 %), and dibenzodioxocins (5-5′, 4 %). Furthermore, the analyses indicated that the lignin is partially acylated at the γ-OH (12 % acylation) by acetate groups and that acetylation occurs preferentially on syringyl-units. As in other plants, acetylation occurs at the monomer stage, and sinapyl acetate behaves as a real lignin monomer participating in lignification in cardoon stalks. The detailed structural characterization of cardoon lignin reported here will foster the industrial use of this biomass for the production of biofuels and other bio-based chemicals under the lignocellulosic biorefinery.

Effect of complete dissolution in LiCl/DMSO on the isolation and characteristics of lignin from wheat straw internode

A modified cellulolytic enzyme lignin (CEL) protocol, named regeneration cellulolytic enzyme lignin (RCEL), was developed for the enhancement of carbohydrate removal and lignin extraction with short ball milling hours. The process of complete dissolution in lithium chloride/dimethyl sulfoxide (LiCl/DMSO) and regeneration in water prior to enzymatic hydrolysis were applied for improving the isolation of CEL from wheat straw internode. The removal of carbohydrates was enhanced with little structural changes of the isolated lignin. More than 90% of the lignin in the enzymatic residue of 4h ball-milled/regenerated internode could be extracted by aqueous dioxane. The final lignin yield of RCEL based on Klason lignin in original internode reached 73.2%, which was 5.0% higher than that of CEL. The S/V ratio of isolate lignin was higher than that of lignin in situ and the increment of S/V ratio was occurred during both enzymatic hydrolysis and dioxane/water extraction steps. The analysis results of wet chemistry and 2D HSQC NMR showed that RCEL was structurally similar to CEL.

Refining of Ethanol Biorefinery Residues to Isolate Value Added Lignins

The isolation of lignin coproducts from the residual solids of a hardwood based biocatalytic bioethanol process was examined, using extraction methods based on aqueous alkali or aqueous ethanol. This work focused on understanding how the structural features of raw lignin in the process residue influenced the refined lignin isolation yields, in addition to polymeric and structural characteristics. On the basis of this approach, the extraction based lignin refining could be optimized. Mild extraction conditions allowed for recovery of approximately 40 wt % of the lignin present in the starting material. This yield could be increased to about 76 wt %, by the application of base or acid catalyzed reactive extraction conditions liberating the bonded insoluble fractions of the residue. All isolated lignin products were characterized in terms of their functional groups, molecular weights and thermal properties. The lignins from mild alkali and ethanol extractions showed similarities in their chemical profiles. I...

Fast Pyrolysis of Four Lignins from Different Isolation Processes Using Py-GC/MS

Pyrolysis is a promising approach that is being investigated to convert lignin into higher value products including biofuels and phenolic chemicals. In this study, fast pyrolysis of four types of lignin, including milled Amur linden wood lignin (MWL), enzymatic hydrolysis corn stover lignin (EHL), wheat straw alkali lignin (AL) and wheat straw sulfonate lignin (SL), were performed using pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS). Thermogravimetric analysis (TGA) showed that the four lignins exhibited widely different thermolysis behaviors. The four lignins had similar functional groups according to the FTIR analysis. Syringyl, guaiacyl and p-hydroxyphenylpropane structural units were broken down during pyrolysis. Fast pyrolysis product distributions from the four lignins depended strongly on the lignin origin and isolation process. Phenols were the most abundant pyrolysis products from MWL, EHL and AL. However, SL produced a large number of furan compounds and sulfur compounds originating from kraft pulping. The effects of pyrolysis temperature and time on the product distributions from corn stover EHL were also studied. At 350 °C, EHL pyrolysis mainly produced acids and alcohols, while phenols became the main products at higher temperature. No obvious influence of pyrolysis time was observed on EHL pyrolysis product distributions.

Evaluating effects of benzene–ethanol extraction on molecular weight of lignin isolated from pretreated bamboo substrate

In a previous study by the authors, it was found that benzene–ethanol extraction (BAE) could remove some of the lignin fragments from pretreated bamboo substrate and therefore cause a decrease in the lignin content of the substrate. In the present study, lignin was isolated by dioxane extraction of enzyme hydrolysis of ball-milled substrate (CEL method), and the effects of BAE on lignin molecular weight (MW) were determined. Results indicated that hydrothermal pretreatment could facilitate lignin isolation substantially when CEL method was used. Lignin fragments with low MW were more sensitive to BAE, and therefore, evident increase in both weight average molecular weight (Mw) and number average molecular weight (Mn) was observed; especially, the increase rate of Mn was more than 2.5 times of Mw when degradation prevailed. However, subtle changes were found in Fourier transform infrared spectroscopy and carbon-13 nuclear magnetic resonance spectra between the lignin samples with and without BAE; the solubility of lignin in benzene–ethanol solution was more dependent on the MW level than on the functional groups in lignin structure.

Kraft delignification of energy crops in view of pulp production and lignin valorization

The hardwoods Acacia dealbata (mimosa), Salix spp. (willow), and the perennial plants Arundo donax (giant reed) and Miscanthus giganteus (giant Chinese silver grass) are important energy crops, with low requirements and high productivity. The polysaccharide content of these species has drawn attention as source of sugars for biobased products. In this work, biomasses were deconstructed by kraft pulping, evaluating final pulp yields as well as residual lignin (kappa number, KN) as indicators of the pulp quality for conversion to sugars. The black liquors and lignin in the isolated materials were evaluated concerning composition and structural characterization parameters with relevance to further valorizations routes, such as production of vanillin and syringaldehyde. The best trade-off between pulp yield and KN were achieved for 160°C and pulping time 210min, with active alkali (AA) 22% for mimosa and willow and AA 18% for giant reed; these three biomasses presented similar pulp yields (45–47%) and KN (13–15). For silver grass a lower AA (16%) and the combination of higher temperature/lower pulping time (170°C/180min) were selected. Among the four, silver grass presented the highest pulp yield (51.5%) and the lowest KN (10), which is the first advantage identified for this species. Another advantage is the higher production of lignin by isolation from black liquor (128g/kg of biomass), compared to the other materials (88–119g/kg), with the additional benefit of low contamination with inorganic compounds. The isolation of lignins is favorable for the valorization route involving oxidative depolymerization. The structural analysis of lignins and the comparison between the frequency of the main interlinkages and functional groups allowed drawing remarks about their suitability for some applications. The data presented are a tool for decision about the best exploitation route for lignin, contributing for the valorization of the streams generated in biorefining processes of energy crops.

Separation of Lignin from Corn Stover Hydrolysate with Quantitative Recovery of Ionic Liquid.

Abundant lignocellulosic biomass could become a source of sugars and lignin, potential feedstocks for the now emergent bio-renewable economy. The production and conversion of sugars from biomass have been well-studied, but far less is known about the production of lignin that is amenable to valorization. Here we report the isolation of lignin generated from the hydrolysis of biomass dissolved in the ionic liquid 1-butyl-3-methylimidazolium chloride. We show that lignin can be isolated from the hydrolysate slurry by simple filtration or centrifugation, and that the ionic liquid can be recovered quantitatively by a straightforward wash with water. The isolated lignin is not only free from ionic liquid, but also lacks cellulosic residues and is substantially depolymerized, making it a promising feedstock for valorization by conversion into fuels and chemicals.

Separation and characterization of lignin obtained by catalytic hydrothermal pretreatment of cotton stalk

A catalytic method for the isolation of lignin in high purity from cotton stalk was presented in this study. Lignin fractions were obtained by the extraction of cotton stalk under catalytic hydrothermal conditions in the presence of metal chlorides including AlCl3, CrCl3, FeCl3 and ZnCl2 as catalysts. Structural elucidation of these lignin samples was investigated by high-performance anion-exchange chromatography (HPAEC), gel permeation chromatography (GPC), and 2D HSQC NMR spectroscopy. The results showed that the separated lignin fractions possessed higher purities than milled wood lignin (MWL). 2D NMR spectra demonstrated that guaiacyl (G) and syringyl (S) units were predominant in these lignin fractions, similar to the typical lignin types of hardwood. Moreover, the obtained lignin fractions consisted mainly of β-O-4′ aryl ether linkages, followed by resinol and phenylcoumaran structures. It was also found that the cleavages of β-O-4′ linkages occurred remarkably due to the presence of catalysts, and their decreasing severities were consistent with the acidity of the metal chlorides. In addition, the degradation was accompanied by a mild repolymerization during the catalytic hydrothermal pretreatment. In consideration of the relatively high yield and purity, isolation of lignin from raw materials by using catalytic hydrothermal pretreatment catalyzed by AlCl3 provided us a more effective approach for biomass pretreatment.

Lignin isolation from spruce wood with low concentration aqueous alkali at high temperature and pressure: influence of hot-water pre-extraction

Lignin was successfully isolated from spruce wood with an accelerated solvent extractor using low concentration aqueous NaOH as an extraction solvent. The biorefinery concept was also applied.

Isolation and Characterisation of Lignolytic Bacteria for Bioethanol Production

In the present century, usage of non-renewable hydrocarbon fuels for sufficing energy demands are not considered environmentally and ecologically sustainable. Second generation biofuel production as lignocellulosic bioethanol is considered a sustainable way for generating fuel. Bioethanol production is considered as an option among other thermo-chemical processes for providing energy in form of ethanol, preserving the ecosystem by reducing the pollutants emitted during fossil fuel combustion. The release of fermentable sugars had been a challenging issue due to the presence of lignin in plant cell walls. This paper focused its study on isolation of novel lignin degrading enzymes from bacteria present in the soil of Western Ghats of India as the region is unhabituated followed by its application for biodegradation of lignocellulosic biomass for bioethanol production. Much has been done for lignin degrading fungi but still there is not a single method of choice which can be applicable on industrial scale successfully. Hence, the present study focuses on the isolation of novel bacteria and their enzymes with lignolytic potential and their application in bioconversion of lignocellulosic biomass into ethanol.

Specific lignin accumulation in granulated juice sacs of Citrus maxima.

Juice sac granulation occurring in pummelo fruits [Citrus maxima (Burm.) Merr.] is an undesirable trait, and the underlying mechanism remains unresolved. Previous studies have shown that lignin metabolism is closely associated with the process of juice sac granulation. Here, a method suitable for lignin isolation from pummelo tissues is established. Acetylated lignins from different pummelo tissues and cultivars were analyzed by HSQC NMR. The results showed that lignins in granulated juice sacs were characterized by an extremely high abundance of guaiacyl units (91.13-96.82%), in contrast to lignins from other tissues, including leaves, stems, and segment membranes. The abnormally accumulated lignins in granulated juice sacs were specific and mainly polymerized from coniferyl alcohol. No significant difference was found in lignin types among various cultivars. These findings indicated that the mechanism of juice sac granulation might be similar among various cultivars, although very different degrees of juice sac granulation can be observed.

Pembuatan Surfaktan Berbahan Dasar Jerami Padi

Indonesia's oil production has declined due to the low level of production of oil wells that have been old. Extraction of oil from the wells can be enhanced by the injection of surfactant. Potential raw material for the manufacture of surfactants, especially the waste material so that lower-priced. This material include lignocellulosic materials and plantation agricultural waste. Rice straw is one of them. This study aims to make surfactants from rice straw. The axpetriment was conducted through the steps of: (1) preparation of raw materials, (2) delignification and isolation of lignin, (3) sulfonation of lignin using NaHSO 3 . Delignification of rice straw held at a temperature of 166 o C and a pressure of 1.2 atm. Sulfonated of lignin conducted at a temperature of 90-95°C and pH 7. Lignin and sodium lignosulfonate tested using FTIR and gravimetric. The results show at 2.5 g lignin, weight percent of NaHSO 3 60% of the weight of lignin, pH 7, temperature 90-95 ° C for 4 hour reaction obtained 2,5509 g of sodium lignosulfonate (SLS). Sodium lignosulfonate is soluble in water. Sodium lignosulfonate phase behavior test using crude oil from Oil Drilling Tanjung, South Kalimantan, at the surfactant concentration 3000 and 5000 ppm result that the type of emulsion is water in oil. So that this surfactant not suggested for EOR.

Isolation and characterization of lignin from the oak wood bioethanol production residue for adhesives

Lignin was isolated from the residue of bioethanol production with oak wood via alkaline and catalyzed organosolv treatments at ambient temperature to improve the purity of lignin for the materials application. The isolated lignins were analyzed for their chemical composition by nitrobenzene oxidation method and their functionality was characterized via wet chemistry method, element analysis, 1H NMR, GPC and FTIR-ATR. The isolated lignin by acid catalyzed organosolv treatment (Acid-OSL) contained a higher lignin content, aromatic proton, phenolic hydroxyl group and a lower nitrogen content that is more reactive towards chemical modification. The lignin-based adhesives were prepared and the bond strength was measured to evaluate the enhanced reactivity of lignin by the isolation. Two steps of phenolation and methylolation were applied for the modification of the isolated lignins and their tensile strengths were evaluated for the use as an adhesive. The acid catalyzed organosolv lignin-based adhesives had comparable bond strength to phenol-formaldehyde adhesives. The analysis of lignin-based adhesives by FTIR-ATR and TGA showed structural similarity to phenol adhesive. The results demonstrate that the reactivity of lignin was enhanced by isolation from hardwood bioethanol production residues at ambient temperature and it could be used in a value-added application to produce lignin-based adhesives.

Properties of Lignin from Oil Palm Empty Fruit Bunch and Its Application for Plywood Adhesive

Lignin from lignocellulosic biomass is a potential biopolymer for wood adhesive. The aims of this study were to characterize lignin isolated from the black liquor of oil palm empty fruit bunch fiber pretreated with steam explosion in alkaline conditions and to examine the bond quality of aqueous polymer isocyanate (API) adhesive prepared from lignin, natural rubber latex (NRL), and polyvinyl a lcohol (PVA) as base polymers with isocyanate crosslinkers. Lignin was precipitated from the black liquor by adding hy drochloric acid; then the precipitate was separated by filtration, thoroughly washed with water up to pH 2 and pH 5, and dried. The isolated lignin was characterized by ultimate analysis, UV spectroscopy, FT-IR spectroscopy, and thermal analysis. Three-layer plywood samples were prepared, and the bond strengths of the plywood samples were dete rmined in dry conditions and after cyclic boiling. The lignin isolates with different pH values did not have sign ificantly different chemical and thermal properties . Both lignin isolates had similar C, H, and O contents, identica l functional groups in the FTIR spectra, similar ab sorption in the UV spectra, and high decomposition temperatures. The b ase polymers composition that could produce API adhesive for exterior applications was NRL/PVA/lignin (4/4/2). T he use of more lignin in the adhesive formulation d ecreased the bond strength of the plywood.

Isolation of novel lignin degrading enzymes and lignin degradation products from bacteria and fungi

Isolation of novel lignin degrading enzymes and lignin degradation products from bacteria and fungi

Lignin deposition during earlywood and latewood formation in Scots pine stems

Lignin deposition at consecutive secondary wall thickening stages of early and late xylem cells during annual ring wood formation in Scots pine (Pinus sylvestris L.) stems was studied. Lignin patterns, isolated by thioglycolic acid method, consisted of alcohol-soluble (LTGA-I) and alkali-soluble (LTGA-II) fractions. The sum of two fractions, being the total lignin content, gradually increased in the course of lignification. However, the increments of lignin amount at each development stage of early and late tracheids were different. The intensity of lignin deposition increased in the course of earlywood tracheid maturation and decreased toward the end of latewood cell differentiation. The deposition of two lignin fractions in each layer of forming wood also occurred oppositely. The increment of LTGA-I descended, whereas that of LTGA-II increased from the beginning to the end of early xylem lignification. In contrast, LTGA-I increment dropped, whereas LTGA-II rose during late xylem lignification. Gel permeation chromatography showed that the lignins, formed at the beginning of lignification, were more homogeneous and had higher molecular weight compared with the lignins at the end of cell differentiation. Besides, the content of cellulose, estimated as the residue after lignin isolation, and of cell wall substances, presented as cell wall cross-section areas, at consecutive maturation stages of early and late xylem cells have been found to be different. The data show that lignin deposition occurred in different conditions and with opposite dynamics during early and late xylem formation.

Isolation of Cellulolytic Enzyme Lignin from Rice Straw Enhanced by LiCl/DMSO Dissolution and Regeneration

Ball-milled rice straw was dissolved in a lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solvent system, regenerated, and subjected to enzymatic hydrolysis to obtain regenerated cellulolytic enzyme lignin (RCEL). The structure of the isolated lignin was characterized by elemental analysis, gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and proton nuclear magnetic resonance (1H NMR). Alkaline nitrobenzene oxidation (NBO) was conducted to analyze the structural characteristics of the in-situ lignin. The results showed that the rice straw RCEL was composed of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) phenylpropane units, with relatively high amounts of H units. The yield of RCEL is about 5% units higher than that of cellulolytic enzyme straw lignin (CEL) on the basis of total lignin in the original rice straw. When compared to the CEL obtained by the traditional method, there were no observed differences versus RCEL in terms of the elemental compositions, NBO product yields, and S/G ratio. The weight-average molecular weight of RCEL was 6835, which was lower than that of CEL, indicating that some rice straw lignin linkages were cleaved during LiCl/DMSO dissolution.

Slow and fast pyrolysis of Douglas-fir lignin: Importance of liquid-intermediate formation on the distribution of products

The formation of liquid intermediates and the distribution of products were studied under slow and fast pyrolysis conditions. Results indicate that monomers are formed from lignin oligomeric products during secondary reactions, rather than directly from the native lignin. Lignin from Douglas-fir (Pseudotsuga menziesii) wood was extracted using the milled wood enzyme lignin isolation method. Slow pyrolysis using a microscope with hot-stage captured the liquid formation (>150 °C), shrinking, swelling (foaming), and evaporation behavior of lignin intermediates. The activation energy (Ea) for 5–80% conversions was 213 kJ mol−1, and the pre-exponential factor (log A) was 24.34. Fast pyrolysis tests in a wire mesh reactor were conducted (300–650 °C). The formation of the liquid intermediate was visualized with a fast speed camera (250 Hz), showing the existence of three well defined steps: formation of lignin liquid intermediates, foaming and liquid intermediate swelling, and evaporation and droplet shrinking. GC/MS and UV-Fluorescence of the mesh reactor condensate revealed lignin oligomer formation but no mono-phenols were seen. An increase in pyrolytic lignin yield was observed as temperature increased. The molar mass determined by ESI-MS was not affected by pyrolysis temperature. SEM of the char showed a smooth surface with holes, evidence of a liquid intermediate with foaming; bursting from these foams could be responsible for the removal of lignin oligomers. Py-GC/MS studies showed the highest yield of guaiacol compounds at 450–550 °C.

Isolation of high quality lignin as a by-product from ammonia percolation pretreatment of poplar wood.

A two-step process combining percolation-mode ammonia pretreatment of poplar sawdust with mild organosolv purification of the extracted lignin produced high quality, high purity lignin in up to 31% yield and 50% recovery. The uncondensed fraction of the isolated lignin was up to 34%, close to that the native lignin (40%). Less lignin was recovered after pretreatment in batch mode, apparently due to condensation during the longer residence time of the solubilised lignin at elevated temperature. The lignin recovery was directly correlated with its molecular weight and its nitrogen content. Low nitrogen incorporation, observed at high ammonia concentration, may be explained by limited homolytic cleavage of β-O-4 bonds. Ammonia concentrations from 15% to 25% (w/w) gave similar results in terms of lignin structure, yield and recovery.