Lignin Extraction Research Articles

Assessment of deep eutectic solvents (DES) to fractionate Paulownia wood within a biorefinery scheme: Cellulosic bioethanol production and lignin isolation

Five deep eutectic solvents (DES) were evaluated to disrupt Paulownia wood structure to produce bioethanol and lignin. The DES formulated with choline chloride:lactic acid provided the most promising result. Temperature (110–130 °C), residence time (30–120 min), molar ratio (1:2–1:9), and liquid-to-solid ratio (8–15 mL/g) were optimized for cellulose recuperation (93% retained in the solid phase) and lignin removal (94% delignification yield). The spent solid was used for bioethanol production, achieving up to 43.6 g ethanol/L (89.7% ethanol yield). Lignin (84% of purity) was isolated from the black liquor and thoroughly characterized by FTIR, 1H NMR, TGA-DTG and SEM, while the liquor after lignin precipitation was chemically characterized for monomers/oligomers, total phenolic content, antioxidant activity and phytochemical profile (highlighting the presence of 25.06, 10.21 and 2.51 mg of syringaldehyde, vanillin and 3,4-dihydroxibenzoic acid per g of initial biomass). Overall, this study show that DES pre-treatment is a promising strategy for simultaneous lignin extraction and cellulose digestibility enhancement.

Direct conversion of lignin-rich black liquor to activated carbon for supercapacitor electrodes

The escalating industrialization trend underscores the imperative for sustainable waste management practices. The present investigation explores a sustainable methodology for managing the waste generated from the kraft process by directly converting it into activated carbon (BLAC) through a cost-effective hydrothermal-assisted activation method. The research involved a comparative analysis of BLAC with acid-washed black liquor lignin-derived activated carbon (ABLAC) and commercial lignin-derived activated carbon (SALAC). The analysis revealed that BLAC possesses a well-developed micro and mesoporous structure, yielding a significantly higher surface area of 2277.2 m2/g as compared to ABLAC (1260 m2/g) and SALAC (1558.4 m2/g). The presence of inherent alkali in the black liquor is the main factor influencing the surface area of the BLAC. Furthermore, it demonstrated impressive electrochemical performance, showing a specific capacitance value of 871.4 F/g at 1 A/g current density, positioning it as a formidable electrode material for supercapacitor applications. The proposed direct conversion strategy will eliminate the need for high-temperature pre‑carbonization and additional lignin extraction, reducing chemical usage and presenting a greener approach.

Extraction of homogeneous lignin oligomers by ozonation of Miscanthus giganteus and vine shoots in a pilot scale reactor

Lignin, a complex phenolic polymer crucial for plant structure, is mostly used as fuel but it can be harnessed for environmentally friendly applications. This article explores ozonation as a green method for lignin extraction from lignocellulosic biomass, aiming to uncover the benefits of the extracted lignin. A pilot-scale ozonation reactor was employed to extract lignin from Miscanthus giganteus (a grass variety) and vine shoots (a woody biomass). The study examined the lignin extraction and modification of the fractions and identified the generation of phenolic and organic acids. About 48 % of lignin was successfully extracted from both biomass types. Phenolic monomers were produced, vine shoots yielding fewer monomers than Miscanthus giganteus. Ozonation generated homogeneous lignin oligomers, although their molecular weight decreased during ozonation, with vine shoot oligomers exhibiting greater resistance to ozone. Extracted fractions were stable at 200 °C, despite the low molecular weight, outlining the potential of these phenolic fractions.

RETRACTED ARTICLE: Microwave-ultrasonic assisted extraction of lignin to synthesize new nano micellar organometallic surfactants for refining oily wastewater

In this work, a beneficial approach for efficient depolymerization of lignin and controllable product distribution is provided. Lignin, an abundant aromatic biopolymer, has the potential to produce various biofuels and chemical adsorption agents and is expected to benefit the future circular economy. Microwave-ultrasonic (MW/US) assisted efficient depolymerization of lignin affords some aromatic materials used in manufacturing the starting material to be investigated. Some nano organometallic surfactants (NOMS) based on Ni2+, Cu2+, Co2+, Fe3+, and Mn2+ besides 2-hydroxynaphth-sulphanilamide are synthesized to enhance oil recovery (EOR). In this work, the assessment of the NOMS’s efficiency was improving the heavy oil recovery via the study of the dynamic interfacial tension (IFT), contact angle, and chemical flooding scenarios. The NOMS-Ni2+ exhibited the maximum reduction of viscosity and yield values. Dropping the viscosity to 819.9, 659.89, and 499.9 Pa s from blank crude oil viscosity of 9978.8, 8005.6, and 5008.6 Pa s respectively at temperatures of 40, 60, and 80 °C was investigated. The reduction of τB values was obtained also by OMS-Ni2+. The minimum IFT was recorded against the Ni2+ derivatives (0.1 × 10–1 mN m−1). The complete wettability alteration was achieved with the NOMS-Ni2+ surfactant (ɵ ≅6.01).\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\cong 6.01).$$\\end{document} The flooding test has been steered in 3 sets using the sand-packed model as a porous media at surfactant concentrations (1, 1.5, 2 and 2.5%) at 50 °C and 499 psi as injection pressure. The best value (ORs) formed for NOMS-Ni2+ were 62, 81, 85.2, and 89% respectively as compared with other NOMS-M2+ at the same concentrations. The mechanism of alternating wettability was described in the text. The rheology of the used heavy crude oil was investigated under temperatures of 40, 60, and 80 °C.Graphical

GREEN ADSORBENT SYNTHESIS FROMORANGE MESOCARP CELLULOSE USING GRAFT COPOLYMERIZATION

The potential of agricultural waste like orange (Citrus sinensis) mesocarp is yet to be explored. Thus, in this study the extractionof green adsorbent that will be renewable, low cost and environmentally friendly from orange mesocarp was examined. The extraction was done using alkali pretreatment method followed by bleaching process to obtain cellulose and dissolvethe hemicellulose, lignin and other extractives. Then, graft copolymerisation of acrylamide onto the cellulose obtainedwas done usingfree radical initiation system. Grafting parameterswere studied by varying the effects of initiator concentrations,monomer to cellulose ratio, temperature and time. Distilled water was used toextract the formedpolyacrylamide (PAam)for 48 hours. And the characterization of the extracted and grafted cellulose samples was carried out by Fourier Transform Infrared Spectroscopy(FTIR).Orange mesocarp gave a cellulose average yield of 29.1%. The optimum grafting conditions were found to be 30OC at a time interval of 2 hours, ratio of monomer to cellulose being 3:1 and initiator concentration of 0.020M. The percentages of polymerization, graft and graft efficiency were 113.40, 86.83 and 45.90respectively. Also, the absorbance peaks of thesamplesconfirmed that grafting was effectively carried out on the cellulose backbone.

Alkali-based lignin extraction from lignocellulosic material and upgradation of residual pulp as bio-packaging material towards sustainable biomass utilization

The current study explored the extraction of lignin from paddy straw and kans grass, while focusing on the yield and physico-chemical properties of lignin. Alkali-based lignin extraction from lignocellulosic biomass indicated a positive correlation between NaOH concentration and lignin yield. An increase in NaOH concentration from 0.50 % to 2.00 % resulted in increased yield of lignin from 129.16 to 447.07 mg/g and 222.79 to 551.37 mg/g of lignin from paddy straw and kans grass, respectively. The extracted lignin was characterized by FTIR and XRD, showed its chemical structure homogeneity with commercial lignin. Bio-packaging specimens were created using residual pulp and characterized for their physical and mechanical properties. The specimens of both the biomass were found to effectively withstand a load of 7.36 kg and 11.17 kg, respectively before crumpling. Further, the mass balance of the optimized process showed its industrial applicability for the fractionation and utilization of lignocellulosic biomass.

Model-based process intensification of deep eutectic solvent treatment of eucalyptus slabs for lignin extraction and pulp production

This work revealed the reaction characteristics in the delignification process of eucalyptus slabs catalyzed by acidic deep eutectic solvent (benzyltriethylammonium chloride/formic acid) from the perspective of heterogeneous reactions. The limitation of internal diffusion on delignification process cannot be ignored. Afterwards, a kinetic model based on cell wall structure was proposed to describe the relationship between the delignification degree and reaction conditions, and it also hold excellent predictive ability for lignin removal, carbohydrate retention and solid residue yield. Compared with other reported kinetic models, this novel model not only took into account all operational parameters of reaction process, but also can be applied to the entire reaction process without the need for segmentation. Besides, an essential requirement based on the developed model was a 44.40 wt% formic acid concentration and a temperature of 130 °C, when the purpose of DES treatment was pulping. Generally, this work could provide guidance on process adjustments and product quality control during the DES processing.

Reactive Eutectic Media for Lignocellulosic Biomass Fractionation.

This study introduces an alternative approach towards lignocellulosic biomass fractionation. For this purpose, reactive eutectic media (REM) based on ammonium formate and different organic acids are investigated, possible products are identified, and the REM are employed for lignin extraction and terminal isolation of cellulose pulp from beech wood. The method promises a considerable process intensification by simultaneous separation of high purity cellulose pulp, lignin isolation as a cationically modified species, and production of value-added chemicals from reaction products of the REM. This study puts a further focus on the generated cellulose pulp and investigates it with respect to surface charge and fiber length.

Extraction and characterization of steam-exploded silane-treated cellulosic natural Vernonia elaeagnifolia long fibre

Steam explosion is a highly successful and environmentally benign fibre-treating method for lignocellulosic fibers that can significantly improve the fibre's properties. The research focuses on utilizing sustainable long-cellulosic natural fibre material to benefit the textile, fibre-strengthened polymer, and engineering industries. A cellulosic natural fibre was extracted from Vernonia elaeagnifolia and further, it was steam exploded and silane-treated with various chemical concentrations. Chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and SEM examination were used to examine the crystallinity and check the morphological properties of raw Vernonia elaeagnifolia fibre (VEF) and steam-exploded silane-treated Vernonia elaeagnifolia fibres. The chemical analysis shows that steam-exploded silane treatments of VEFs removed lignin, hemicelluloses, and other extractives. The highest crystallinity of 75.86% was found in 13% of steam-exploded silane-treated VEF and for 5% of steam-exploded silane-treated VEF, it was about 70.22%, which is confirmed through the XRD analysis. The tensile strength of steam-exploded 5% silane-treated VEF was 470.67 MPa, while Young's modulus was 18.7 GPa. The obtained result suggests that steam-exploded silane-treated VEFs are suitable fibres to strengthen polymer composite materials in a sustainable way.

High extraction and excellent anti-UV and anti-oxidant proprieties of lignin from Reseda Luteola L. waste by organosolv process

Lignin is an abundant natural biopolymer found in plant cell walls. Lignin can come from tinctorial plants, whose residual biomass after dye extraction was typically discarded as waste. The main objective of this study was to extract lignin from the residual biomass of Reseda luteola L. using an organosolv process and to optimize the extraction conditions. The extracted lignin was characterized, and its potential applications as an antimicrobial, anti-oxidant, and anti-UV agent were investigated. Response surface methodology based on a Box-Behnken design was employed to optimize the lignin extraction conditions (organic acid concentration, material-to-liquid ratio, extraction time). The extracted lignin was comprehensively characterized using NMR, FTIR, XRD, SEM-EDX, TGA, DSC, and UV–Vis techniques. The optimal extraction conditions yielded a remarkably high lignin recovery of 62.41 % from the plant waste, which was rarely achieved for non-wood plants in previous works. The extracted lignin exhibited excellent thermal stability and radical scavenging anti-oxidant activity but no significant antimicrobial effects. Treating wool fabrics with lignin nanoparticles substantially enhanced UV protection from the “good” to “excellent” category based on the UPF rating. This sustainable valorization approach converted abundant tinctorial plant waste into high-purity lignin with promising anti-oxidant and UV-blocking properties suitable for various applications.

Integral valorization of two-phase olive mill waste: extraction of cellulose and lignin and their characterization

Integral valorization of two-phase olive mill waste: extraction of cellulose and lignin and their characterization

Isolation and characterisation of lignin using natural deep eutectic solvents pretreated kenaf fibre biomass

Extraction of lignin via green methods is a crucial step in promoting the bioconversion of lignocellulosic biomasses. In the present study, utilisation of natural deep eutectic solvent for the pretreatment of kenaf fibres biomass is performed. Furthermore, extracted lignin from natural deep eutectic solvent pretreated kenaf biomass was carried out and its comparative study with commercial lignin was studied. The extracted lignin was characterized and investigated through Infrared Fourier transform spectroscopy, X-ray Diffraction, thermogravimetric analysis, UV–Vis spectroscopy, and scanning electron microscopy. FTIR Spectra shows that all samples have almost same set of absorption bands with slight difference in frequencies. CHNS analysis of natural deep eutectic solvent pretreated kenaf fibre showed a slight increase in carbon % from 42.36 to 43.17% and an increase in nitrogen % from − 0.0939 to − 0.1377%. Morphological analysis of commercial lignin shows irregular/uneven surfaces whereas natural deep eutectic solvent extracted lignin shows smooth and wavy surface. EDX analysis indicated noticeable peaks for oxygen and carbon elements which are present in lignocellulosic biomass. Thermal properties showed that lignin is constant at higher temperatures due to more branching and production of extremely condensed aromatic structures. In UV–VIS spectroscopy, commercial lignin shows slightly broad peak between 300 and 400 nm due to presence of carbonyl bond whereas, natural deep eutectic solvent extracted lignin does not show up any peak in this range. XRD results showed that the crystallinity index percentage for kenaf and natural deep eutectic solvent treated kenaf was 70.33 and 69.5% respectively. Therefore, these innovative solvents will undoubtedly have significant impact on the development of clean, green, and sustainable products for biocatalysts, extraction, electrochemistry, adsorption applications.

Selective lignin extraction by deep eutectic solvents for the green preparation of bagasse fibers with different lignin contents

In this work, a series of deep eutectic solvents (DES) were prepared using varying proportions of choline chloride and lactic acid. The DES were then employed to selectively extract lignin from bagasse fibers, resulting in bagasse fibers with varying lignin contents. By manipulating the lactic acid composition, bagasse fibers with lignin content ranging from 3.79 to 11.73 wt% of the total weight of the original bagasse were successfully produced, retaining most of the cellulose. Furthermore, the dissolution mechanism of the DES was experimentally characterized. These findings indicate that an increase in the lactic acid level leads to a finer particle size and dissolved cellulose shape. Furthermore, the mechanism by which lactic acid content influences the extraction of lignin units was investigated along with the morphological and elemental changes of cellulose within bagasse fibers after extraction. Additionally, the changes in structural composition, molecular weight, and β-d-xylopyranoside content of lignin were analyzed. This study offers novel perspectives on the environmentally friendly processing of cellulosic material with various lignin contents.

Efficient extraction of lignin from moso bamboo by microwave-assisted ternary deep eutectic solvent pretreatment for enhanced enzymatic hydrolysis

Applications of deep eutectic solvent (DES) systems to separate lignocellulosic components are of interest to develop environmentally friendly processes and achieve efficient utilization of biomass. To enhance the performance of a binary neutral DES (glycerol:guanidine hydrochloride), various Lewis acids (e.g., AlCl3·6H2O, FeCl3·6H2O, etc.) were introduced to synthesize a series of ternary DES systems; these were coupled with microwave heating and applied to moso bamboo. Among the ternary DES systems evaluated, the FeCl3-based DES effectively removed lignin (81.17%) and xylan (85.42%), significantly improving enzymatic digestibility of the residual glucan and xylan (90.15% and 99.51%, respectively). Furthermore, 50.74% of the lignin, with high purity and a well-preserved structure, was recovered. A recyclability experiment showed that the pretreatment performance of the FeCl3-based DES was still basically maintained after five cycles. Overall, the microwave-assisted ternary DES pretreatment approach proposed in this study appears to be a promising option for sustainable biorefinery operations.

Green Silver Nanoparticles Synthesized Using Lignin Extracted from Phoenix Dactylifera Seed: Application as Electrochemical Sensor for the Monitoring of Ornidazole

Lignin is the second most common biopolymer after cellulose and the most-available renewable source of aromatic groups in nature. The alkaline method was used to extract lignin from Phoenix dactylifera seeds powder. The current research aims to use extracted lignin as a reducing and stabilizing agent for ecofriendly manufacturing of silver nanoparticles (Lig-AgNPs). The prepared Lig-AgNPs were characterized by UV–vis, scanning electron microscopy, and energy-dispersive X-ray analysis techniques. Moreover, they were further used to modify the surface of a carbon paste electrode (CPE), and the resulting modified electrode (Lig-AgNPs/CPE) was applied for electrochemical detection of ornidazole (ODZ) according to optimum square wave voltammetry conditions. The prepared sensor Lig-AgNPs/CPE was able to identify ODZ (at BR buffer pH 2.3) in a linear range between 8.0 × 10−6 and 1.0 × 10−3 M, with DL of 0.362 μM and QL equal 1.21 μM, the acquired RSD was 3%. Additionally, the developed electrode Lig-AgNPs/CPE was successfully applied to detect ODZ in commercial milk, river water, and tap water with agreeable results.

Sequential extraction of hesperidin, pectin, lignin, and cellulose from orange peels: towards valorization of agro‐waste

AbstractTo maximize the reuse of citrus fruit processing waste, which is generated in large amounts due to juice production, this work shows the results of a new renewable approach for the extraction of high‐added‐value compounds present in orange biomass, specifically in orange peels (OP). The method is based on the use of diluted Ca2+, acid, and base solutions for the extraction of hesperidin (HSD), pectin, lignin, and cellulose sequentially, without generating any organic solid waste at the end, and without the need for air drying the starting biomass. Good yields of hesperidin were recovered (~1.56%), with excellent purity (up to 95%), as well as lignin (yield ~2.2%) and cellulose (yield ~12%). Pectin obtained by this process showed a high amount of galacturonic acid (~88%) and a low degree of methylation (~16%). All products were thoroughly characterized by applying Fourier transform infrared (FTIR) spectroscopy and solid‐state cross‐polarization/magic angle spinning carbon‐13 nuclear magnetic resonance spectroscopy (CP/MAS 13C‐NMR). The products recovered from OP can be applied in a wide array of fields, such as food, medicine, and pharmaceuticals, among others.

Pure lignin induces overexpression of cytochrome P450 (CYP) encoding genes and brings insights into the lignocellulose depolymerization by Trametes villosa

Trametes villosa is a remarkable white-rot fungus (WRF) with the potential to be applied in lignocellulose conversion to obtain chemical compounds and biofuels. Lignocellulose breakdown by WRF is carried out through the secretion of oxidative and hydrolytic enzymes. Despite the existing knowledge about this process, the complete molecular mechanisms involved in the regulation of this metabolic system have not yet been elucidated. Therefore, in order to understand the genes and metabolic pathways regulated during lignocellulose degradation, the strain T. villosa CCMB561 was cultured in media with different carbon sources (lignin, sugarcane bagasse, and malt extract). Subsequently, biochemical assays and differential gene expression analysis by qPCR and high-throughput RNA sequencing were carried out. Our results revealed the ability of T. villosa CCMB561 to grow on lignin (AL medium) as the unique carbon source. An overexpression of Cytochrome P450 was detected in this medium, which may be associated with the lignin O-demethylation pathway. Clusters of up-regulated CAZymes-encoding genes were identified in lignin and sugarcane bagasse, revealing that T. villosa CCMB561 acts simultaneously in the depolymerization of lignin, cellulose, hemicellulose, and pectin. Furthermore, genes encoding nitroreductases and homogentisate-1,2-dioxygenase that act in the degradation of organic pollutants were up-regulated in the lignin medium. Altogether, these findings provide new insights into the mechanisms of lignocellulose degradation by T. villosa and confirm the ability of this fungal species to be applied in biorefineries and in the bioremediation of organic pollutants.

Extraction, recovery, and characterization of lignin from industrial corn stover lignin cake

Lignin utilization in value-added co-products is an important component of enabling cellulosic biorefinery economics. However, aqueous dilute acid pretreatments yield lignins with limited applications due to significant modification during pretreatment, low solubility in many solvents, and high content of impurities (ash, insoluble polysaccharides). This work addresses these challenges and investigates the extraction and recovery of lignins from lignin-rich insoluble residue following dilute acid pretreatment and enzymatic hydrolysis of corn stover using three extraction approaches: ethanol organosolv, NaOH, and an ionic liquid. The recovered lignins exhibited recovery yields ranging from 30% for the ionic liquid, 44% for the most severe acid ethanol organosolv condition tested, and up to 86% for the most severe NaOH extraction condition. Finally, the fractional solubilities of different recovered lignins were assessed in a range of solvents and these solubilities were used to estimate distributions of Hildebrand and Hansen solubility parameters using a novel approach.

Lignin-rich extracts as slow-release coating for phosphorus fertilizers

Lignin (L) is the most abundant three-dimensional polymer with versatile yet attractive structural features and chemical properties for applicability as a coating. The properties of lignin are mainly related to its botanical origin, structure and extraction method. Although there has been a lot of interest in using lignin in fertilizing systems, only limited attempts have been dedicated to studying the effect of the lignin structure and origin on the release of P fertilizer. Thus, the aim of this work was to study the effect of lignin polymers, extracted from different plant biomass, as coating materials for P fertilizers. Thus, the effect of the structural features originating from the botanical origin on the properties of coated fertilizers and their slow release were established. To this end, three lignocellulosic biomass, namely olive pomace (OP), barley straw (BS) and wood shavings (WS) were used as feedstock to extract lignin polymers. Those chemical compositions and thermochemical properties were characterized prior to their application as coating for triple super phosphate (TSP) fertilizer. Coated fertilizers were characterized for their morphology and coating thickness prior to their evaluation as slow release P-based fertilizer. A distinct slow P release behavior was reported for lignin-coated fertilizers with TSP@L-OP being the slowest as compared to TSP@L-WS, TSP@L-BS as well as pristine TSP, which confirm that the botanical origin and most likely the chemical structures of lignin has significant impact on the properties of the coating materiel. A 100 % release of P from the uncoated TSP was observed after 3 days, while the released amount ranged from only 16.9 % for TSP@L-OP up to 33.4 % for TSP@L-BS. The impact of these coated fertilizers on nutrients uptake and wheat growth was also scrutinized and an noticeable improvement of wheat shoot biomass was observed with the coated TSP treatments reaching up 57.8 % for TSP@BS, 78.1 % for TSP @WS and 93.7 % for TSP @OP, compared to uncoated TSP. This was concomitant to a slight increase of P concentration in shoots, roots and rhizosphere soil, which confirmed the positive effect of slow release P fertilizers on plant growth.

Photocatalytic, Oxidative Cleavage of C-C Bond in Lignin Models and Native Lignin.

It is challenging to realize the selective C-C bond cleavage of lignin β-O-4 linkages for production of high-value aromatic chemicals due to its intrinsic inertness and complex structure. Here we report a light-driven, chlorine-radical-based protocol to realize the oxidative C-C bond cleavage in various lignin model compounds catalyzed by commercially available TPT and CaCl2, achieving high conversion and good to high product yields at room temperature. Mechanistic studies reveal that the preferential activation of Cβ-H bond facilitates the oxidation and C-C bond cleavage of lignin β-O-4 model via chlorine radical. Furthermore, this method is also applicable to the depolymerization of natural lignin extracts, furnishing the aromatic oxygenates from the cleavage of Cα-Cβ bonds. This study provides experimental foundations to the depolymerization and valorization of lignin into high value-added aromatic compounds.