Lignin Extraction Research Articles

Light-colored lignin extraction by ultrafiltration membrane fractionation for lignin nanoparticles preparation as UV-blocking sunscreen

A wide range of applications are available for kraft lignin (KL). However, the dark color and wide size distribution of KL make it challenging to use in cosmetics and nanoparticle preparation. In this study, we fractionated KL from a paper-making enterprise using ultrafiltration membrane fractionation, and obtained four kinds of lignin with different molecular weights, namely ultrafiltration lignin (UL). Following that, lignin nanoparticles (ULNPs) were formed by self-assembly from four types of UL. Analyzing the UL and ULNP properties, the low molecular weight lignin, such as ULA, exhibited good antioxidant properties (89.47 %, 5 mg/mL), high brightness (ISO% = 7.55), high L⁎ value (L⁎ = 72.3) and low polydispersity index (PDI = 1.41). The ULNP showed a narrow size distribution (0.8–1.4 m) and high dispersibility in sunscreen. When ULNP was added to sunscreen with 5 % load, its sun protection factor (SPF) value increased from 14.93 to 63.74. Therefore, this study offered an effective way for the comprehensive utilization of pulping waste KL.

Effective fractionation of lignocellulose components and lignin valorization by combination of deep eutectic solvent with ethanol.

Introduction: A combination of deep eutectic solvent with ethanol was developed for pretreatment of Broussonetia papyrifera to effectively extract lignin and promote the subsequent enzymatic hydrolysis. Methods: In order to further explore the optimal conditions for enzymatic hydrolysis, a central composite design method was applied. Results and Discussion: The correlation between each factor and glucose yield was obtained, and the optimal conditions was 160°C, 60min, the ratio of DES to E was 1/1 (mol/mol). The results showed that compared with control, the glucose yield increased by 130.67% under the optimal pretreatment conditions. Furthermore, the specific surface area of biomass was increased by 66.95%, and the content of xylan and lignin was decreased by 86.71% and 85.83%. The correlation between xylan/lignin removal and enzymatic hydrolysis showed that the removal of lignin facilitated the glucose yield more significantly than that of xylan. To further explore the lignin valorization, the structural and antioxidant analysis of recovered lignin revealed that high temperature was favorable for lignin with good antioxidant performance. This pretreatment is a promising method for separating lignin with high antioxidant activity and improving cellulose digestibility.

Facile and sustainable preparation of hierarchical porous carbon material from lignin/DES mixture after pretreatment

Deep eutectic solvent (DES) pretreatment of lignocellulose is an appealing and green approach for efficient lignin extraction. However, the process of lignin regeneration and DES recovery was time-consuming and labor-intensive. Herein, without any separation and purification after the DES pretreatment of Eucalyptus, the lignin/DES mixture was firstly used to fabricate hierarchical porous carbon materials through DES-thermal carbonization (DTC) and activation. Results revealed that the DTC processing involved degradation, condensation, aromatization, and aggregation, which significantly improved the carbonization degree and thermostability of carbon materials. X-ray photoelectron spectroscopic results confirmed the introduction of nitrogen atom from the choline chloride/lactic acid DES into the fabricated carbon materials during the DTC processing. This phenomenon can generate extra pseudocapacitance and thus increase the specific capacitance of supercapacitors. The capacitance retention of the resultant porous carbon materials (AC-200–12) reached above 95% after 10,000 charge-discharge cycles, which was much superior to commercial activated carbon. This facile and sustainable methodology overcomes traditional complex and expensive methods for preparing carbon materials from hardwood, which show promising potential to be used as electrode materials in a supercapacitor.

High value-added lignin extracts from sugarcane by-products

This study evaluates the production of lignin bioactive extracts from sugarcane bagasse (SCB) and straw (SCS) alkaline black liquors using greener precipitating agents (methane sulfonic acid (MSA), formic acid (FA) and lactic acid (LA)) as replacers of sulfuric acid (SA), the most common one used in industry. Results showed that the highest precipitation yield was achieved by LA when applied to SCB (14.5 g extract/100 g SCB). Lignin SCB extracts were similar in composition in terms of total carbohydrates (61–70 %), lignin (22–30 %) and inorganics (1.6–2.6 %). Regarding the SCS extracts, similar yields were obtained among all extracts, however, differences in composition were observed between SA and greener precipitating agents, particularly in terms of sugar content. All extracts exhibited radical scavenging activity; overall the extracts were more effective in the scavenging of ABTS radical. FA was the most promising alternative to SA to recover lignin bioactive extracts. This work suggests organic acids as good candidates for obtaining valuable extracts from alkaline pulping of SCB and SCS instead of the conventional sulfuric acid.

Lignin extraction from lignocellulosic biomass (sugarcane bagasse) and its potential application as a feedstock for fuel production

Biomass can be categorised based on three macromolecular substances: hemicellulose, cellulose, and lignin. Lignin is the next abundant and vital organic substance in the plant's creation, and it is biodegradable. The present paper deals with the extraction of lignin from bagasse, a biomass waste, and its subsequent conversion to biofuel utilising a low-temperature transesterification technique. Lignin was successfully extracted from sugarcane bagasse and characterised by means of Nuclear magnetic resonance (NMR) technique. Using Response Surface Methodology, transesterification process three process variables were optimized: methanol (8–20 vol/vol), time (60–180 min), and catalyst (0–2 wt./wt.%). Extraction of lignin is confirmed by nuclear magnetic resonance (NMR) spectra, which exhibit peaks attributable to the carboxylic group, saturate aliphatic, and phenolic hydroxyl. A fuel yield of 84.65 % was attained with a 20:1 methanol to oil ratio, 1 % catalyst concentration, and 180-minute reaction time. The amount of methanol, reaction time, and catalyst concentration all had a substantial impact on fuel production. A model has been prepared to show the relationship of fuel yield with reaction time, catalyst concentration, and methanol.

The effects of lignin source and extraction on the composition and properties of biorefined depolymerization products

Source and extraction modify lignin structure and subsequent processing. Under our biorefining conditions, organosolv herbaceous lignin yields maximum antioxidant capacity.

Construction of anhydrous two-step organosolv pretreatment of lignocellulosic biomass for efficient lignin membrane-extraction and solvent recovery

Glycerol organosolv (GO) pretreatment has been revealed to be potent in selectively deconstructing the lignocellulosic biomass and effectively enhancing its enzymatic hydrolysis, but the conventional solid washing and GO lignin extraction processes frequently consume large amounts of water, resulting additionally in difficulty recycling the glycerol. In this study, an anhydrous two-step organosolv pretreatment process was explored, followed by the membrane ultrafiltration of glycerol lignin. The results showed that the solid washing of the residual glycerol after the atmospheric glycerol organosolv (AGO) pretreatment was necessary for the subsequent operation of high-solid enzymatic hydrolysis. Washing with ethanol was desirable as an alternative to water as only a low glycerol content of 5.2% resided in the substrate. Membrane ultrafiltration was helpful in extracting the AGO lignin from the pretreatment liquor, in which a high lignin extraction of 81.5% was made with a regenerated cellulose membrane (cut-off for 1 kDa) under selected ultrafiltration conditions. With the characterization of membrane-extracted lignin, it was observed for the first time that the AGO lignin has a well-preserved structure of G/S type. Moreover, the lignin was enriched with reactive groups, i.e. β-O-4′ linkages and aliphatic hydroxyl groups, which was very likely due to the glycerol grafting onto the lignin via α-etherification reaction. The two-step organosolv pretreatment process allowed 86% of glycerol and 92% of the ethanol recovery with ∼78% of distillation energy savings, which was applicable for extraction of organosolv lignin and recycling use of organic solvents.

Native lignin extraction from soft- and hardwood by green and benign sub/supercritical fluid extraction methodologies.

Lignin constitutes an impressive resource of high-value low molecular weight compounds. However, robust methods for isolation of the extractable fraction from lignocellulose are yet to be established. In this study, supercritical fluid extraction (SFE) and CO2-expanded liquid extraction (CXLE) were employed to extract lignin from softwood and hardwood chips. Ethanol, acetone, and ethyl lactate were investigated as green organic co-solvents in the extractions. Additionally, the effects of temperature, CO2 percentage and the water content of the co-solvent were investigated using a design of experiment approach employing full factorial designs. Ethyl lactate and acetone provided the highest gravimetric yields. The water content in the extraction mixture had the main impact on the amount of extractable lignin monomers (LMs) and lignin oligomers (LOs) while the type of organic solvent was of minor importance. The most effective extraction was achieved by using a combination of liquid CO2/acetone/water (10/72/18, v/v/v) at 60 °C, 350 bar, 30 min and 2 mL min-1 flow rate. The optimized method provided detection of 13 LMs and 6 lignin dimers (LDs) from the hardwood chips. The results demonstrate the potential of supercritical fluids and green solvents in the field of mild and bening lignin extraction from wood.

DES: their effect on lignin and recycling performance.

Lignocellulosic biomass raw materials are renewable resources with abundant reserves in nature, and have many advantages, such as being green, biodegradable and cheap. Lignin, one of the three significant components of lignocellulose, possesses a chemical structure rich in phenylpropane and is a primary aromatic resource for the bio-based economy. For the extraction and degradation of lignin, the most common method is the pretreatment of lignocellulose with deep eutectic solvents (DES), which have similar physicochemical properties to ionic liquids (ILs) but address the disadvantages associated with ILs (DES have the advantages of low cost, low toxicity, and non-flammability). In lignocellulose pretreatment, a large amount of solvent is generally required to achieve the desired effect. However, after treatment, a substantial volume of solvent will be wasted, and thus, the problem of the recovery and reuse of DES solution needs to be adequately solved. The methods and mechanisms of perfect DES regeneration will be discussed from the perspective of the elemental composition and features of DESs in this review, which will also outline the present DES recovery methods, such as rotary evaporation, membrane separation, freeze-drying, electrodialysis, etc. The detailed process and the advantages and disadvantages of each method since 2018 are introduced in detail. Future DES recovery methods have been prospected, and the optimization of the functional properties of DESs after recovery is discussed. It is expected to find a convenient and efficient application method for DES extraction or degradation of lignin with low energy and low cost.

Revisiting organosolv strategies for sustainable extraction of valuable lignin: the CoffeeCat process

The CoffeeCat process is an innovative and sustainable strategy for the selective extraction and co-valorisation of polymers from lignocellulosic biomass requiring only green solvents and reagents: water, coffee furanone, glutamic acid.

Characterization of Formacell Lignin Derived from Black Liquor as a Potential Green Additive for Advanced Biocomposites

Black liquor is obtained as a by-product of the pulping process, which is used to convert biomass into pulp by removing lignin, hemicelluloses and other extractives from wood to free cellulose fibers. Lignin represents a major constituent in black liquor, with quantities varying from 20% to 30%, of which a very low share is used for manufacturing value-added products, while the rest is mainly burned for energy purposes, thus underestimating its great potential as a raw material. Therefore, it is essential to establish new isolation and extraction methods to increase lignin valorization in the development of bio-based chemicals. The aim of this research work was to determine the effect of KOH or ethanol concentration as an isolation agent on lignin yields and the chemical characteristics of lignin isolated from formacell black liquor of oil palm empty fruit bunch (OPEFB). Isolation of lignin was carried out using KOH with various concentrations ranging from 5% to 15% (w/v). Ethanol was also used to precipitate lignin from black liquor at concentrations varying from 5% to 30% (v/v). The results obtained showed that the addition of KOH solution at 12.5% and 15% concentrations resulted in better lignin yield and chemical properties of lignin, i.e., pH values of 3.86 and 4.27, lignin yield of 12.78% and 14.95%, methoxyl content of 11.33% and 10.13%, and lignin equivalent weights of 476.25 and 427.03, respectively. Due to its phenolic structure and rich functional groups that are favorable for modifications, lignin has the potential to be used as a green additive in the development of advanced biocomposite products in various applications to replace current fossil fuel-based material, ranging from fillers, fire retardants, formaldehyde scavengers, carbon fibers, aerogels, and wood adhesives.

Recent advances in use of 4- coumarate coenzyme a ligase (4CL) as target gene for improving delignification of paper pulp in Leucaena leucocephala in Indian perspective: A review & case study

Lignin provides support to plants by filling the gaps in cellulose, hemicellulose and pectin components but it is an undesired ingredient of pulp as it imparts black to brown colour to the pulp during paper making process. To remove lignin a lot of chemicals and bleaching agents are used which contribute to major fraction of environmental pollution as well as cost determination of paper making process. In India majorly Leucaena leucocephala is employed for obtaining pulp raw material owing to its properties suited for paper production such as vessel percentage, felting power, runkel ratio, tensile strength etc which is better than other commonly employed sources for paper pulp as raw material. In this review paper we focused on recent advances in the use of 4CL enzyme as target gene towards achieving model designer Leucaena leucocephala trees which can be a possible solution to this problem significantly minimizing the environmental pollution and cost of production. It is known from previous studies that better S/G lignin monomer ratio favours easy extractability of lignin from pulp. Different isoforms with different substrate specificities are known in different plants and knowledge of this differential substrate specificity in conjunction with regulation of expression of these isoforms can help in attaining desired S/G lignin monomer ratio. Thus, these model designer plants would be capable of naturally producing easily amenable lignin towards delignification by altering the S/G lignin ratio and can significantly cut the environmental pollution and cost determining factors for paper production.

Two-step separation of lignin from poplar wood powder using malic acid/choline chloride deep eutectic solvents

Deep eutectic solvents (DESs) have been extensively studied for lignin extraction from lignocellulosic biomass due to their easy synthesis, selective lignin dissolution, high recyclability, and other benefits.

High-purity lignin from selective biomass fractionation with ternary deep eutectic solvents

Green and recyclable ternary deep eutectic solvent was developed to selectively extract lignin of high purity, desirable molecular weight and monomeric yield for applications in reinforcement materials and bio-oil was produced from biomass.

Evaluation of oxy-organosolv pretreatment on lignin extraction from wheat straw

To develop a characteristic “Lignin-first” strategy, the oxy-organosolv delignification processes under mild conditions were comprehensively investigated. Results showed that lignin yield could achieve about 50 % under the optimum process conditions of ethanol concentration 80 %, temperature 90 °C, liquid to wheat straw ratio 25:1 for powdery-scale substrates, which was 65.0 % higher than that for rod-scale substrates under the same conditions. The lignin structural and carbohydrate component results demonstrated the employment of oxygen induced great quantities of lignin dissolving out on the premise of little carbohydrate component (<1 %) and lignin structural (mainly β-O-4 units) changes. Moreover, based on the molecular weight and polydiversity comparison results, the aqueous oxygen could transfer homogeneously in mild organosolv system and result in lignin degradation uniformly. Besides, the employment of oxygen assisted in not only extending the massive lignin removal stage to 30 min and 50 min for P-OEEL and R-OEEL respectively, but also boost the delignification rate with comparison to P-EL and R-EL. Lastly, the excellent anti-oxidant properties of lignin from oxy-organosolv process were demonstrated by scavenging DPPH and ABTS radicals. The economic calculations showed that the cost for lignin production were about 1.58USD/g lignin from powdery-scale wheat straw, providing a competitive route for high-value utilize waste biomass.

Effect of Dilute Acid Pretreatment and Lignin Extraction Conditions on Lignin Properties and Suitability as a Phenol Replacement in Phenol-Formaldehyde Wood Adhesives.

Corn stover was subjected to dilute sulfuric acid pretreatment to assess the impact of pretreatment conditions on lignin extractability, properties, and utility as a phenol replacement in wood phenol-formaldehyde (PF) adhesives. It was identified that both formic acid and NaOH could extract and recover 60-70% of the lignin remaining after pretreatment and enzymatic hydrolysis under the mildest pretreatment conditions while simultaneously achieving reasonable enzymatic hydrolysis yields (>60%). The availability of reaction sites for the incorporation of lignins into the PF polymer matrix (i.e., unsubstituted phenolic hydroxyl groups) was shown to be strongly impacted by the pretreatment time and the recovery. Finally, a lignin-based wood adhesive was formulated by replacing 100% of the phenol with formic-acid-extracted lignin, which exhibited a dry shear strength exceeding a conventional PF adhesive. These findings suggest that both pretreatment and lignin extraction conditions can be tailored to yield lignins with properties targeted for this co-product application.

Environment Friendly Pretreatment Approaches for the Bioconversion of Lignocellulosic Biomass into Biofuels and Value-Added Products

An upsurge in global population and rapid urbanization has accelerated huge dependence on petroleum-derived fuels and consequent environmental concerns owing to greenhouse gas emissions in the atmosphere. An integrated biorefinery uses lignocellulosic feedstock as raw material for the production of renewable biofuels, and other fine chemicals. The sustainable bio-economy and the biorefinery industry would benefit greatly from the effective use of lignocellulosic biomass obtained from agricultural feedstocks to replace petrochemical products. Lignin, cellulose, hemicellulose, and other extractives, which are essential components of lignocellulosic biomass, must be separated or upgraded into useful forms in order to fully realize the potential of biorefinery. The development of low-cost and green pretreatment technologies with effective biomass deconstruction potential is imperative for an efficient bioprocess. The abundance of microorganisms along with their continuous production of various degradative enzymes makes them suited for the environmentally friendly bioconversion of agro-industrial wastes into viable bioproducts. The present review highlights the concept of biorefinery, lignocellulosic biomass, and its valorization by green pretreatment strategies into biofuels and other biochemicals. The major barriers and challenges in bioconversion technologies, environmental sustainability of the bioproducts, and promising solutions to alleviate those bottlenecks are also summarized.

Effect of Dilute Acid Pretreatment and Lignin Extraction Conditions on Lignin Properties and Suitability as a Phenol Replacement in Phenol-Formaldehyde Wood Adhesives

Effect of Dilute Acid Pretreatment and Lignin Extraction Conditions on Lignin Properties and Suitability as a Phenol Replacement in Phenol-Formaldehyde Wood Adhesives

Preparation of alkali lignin extracted from ligno-cellulosic populus tremula fibers: Application to copper oxide nanoparticles synthesis, characterization, and methylene blue biosorption study

The green synthesis of nanoparticles using biogenic approaches constitutes a challenge for effective applications. The massive aliphatic hydroxyl groups of lignin exhibited excellent reduction properties allowing the production of metallic nanoparticles. In this work, alkali lignin was extracted from virgin populus tremula and used for the preparation of copper oxide nanoparticles. The analysis of the prepared nanoparticles was assessed using Fourier Transform Infra-red (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), and Transmission Electron Microscopy (TEM). FT-IR results displayed that different phytochemicals constituents of lignin extract were responsible for the production of CuO nanoparticles. XRD information demonstrated monoclinic CuO nanoparticles with a mean size of 12.4 nm. SEM images showed that some nanoparticles were quite separated from each other and some of them were agglomerated due to the oxidation of metal nanoparticles. TEM photos indicated that the overlap of the nanoparticles resulted in rectangular patterns due to the presence of lignin on the surface of CuO nanoparticles. Finally, the prepared CuO nanoparticles were applied for the removal of methylene blue from water. The results showed that the maximum adsorption capacity reached 85 mg/g at the following conditions: T = 20 °C, pH = 6, and time = 60 min.

Nanolignin-based high internal phase emulsions for efficient protection of curcumin against UV degradation

As an emulsifier, lignin exhibits excellent UV resistance on drug-loaded emulsion systems for drug delivery. However, due to the structural variation and complexity of lignins from various origins, their UV shielding performance varies with the techniques for lignin extraction, which impacts properties and the protection efficiency of lignin-based HIPEs (high internal phase emulsions). In this work, lignin nanoparticles, prepared from three lignin preparations of Eucalyptus, were used in HIPEs delivery systems to protect curcumin from degradation by UV radiation. Structures of the lignin preparations were characterized using 2D HSQC (heteronuclear single-quantum coherence) NMR (nuclear magnetic resonance), 31P NMR, and GPC (gel permeation chromatography). The residual curcumin level after 36 h UV exposure in the nanolignin-based HIPEs was over 72 %, much higher than that (< 10 % after 24 h UV exposure) in the oil phase without lignin, indicating that the nanolignin-based HIPEs with enhanced UV shielding ability protect curcumin better. Of the three lignin preparations, AL (alkali lignin), with the lowest molecular weight, highest contents of phenolic hydroxyl and carboxyl groups, and highest S/G ratio, displayed the best anti-UV radiation ability and the most uniform nanoparticle size.