Lignin Extraction Research Articles

Ce–Zr-based mixed oxide catalyst for oxidative depolymerization of kenaf stalk (biomass) into vanillin

Since petroleum became depleted, rapid attention has been devoted to renewable energy sources such as lignocellulosic biomass to produce useful chemicals for industry (for instance vanillin). Three primary components of lignocellulose are lignin, cellulose, and hemicellulose. This paper uses microwave-assisted technology to oxidize the kenaf stalk (lignocellulosic biomass) and extract lignin to produce vanillin. Catalysts with variable acid–base and redox properties are essential for the mentioned effective conversion, for this reason, CeO2–CA, ZrO2–CA, and CeZrO2–CA catalysts were synthesized. The citrate complexation method was used for the catalyst synthesis and the physicochemical characteristics were analyzed by XRD, FTIR, FE–SEM, TEM, BET, and TPO. The characterization results demonstrated that CeZrO2–CA shows the smallest sized crystallites with a large specific surface area among the other chosen catalysts. For vanillin production, the effect of reaction temperature, reaction time, and catalyst loading was studied. It was observed that compared to other catalysts, CeZrO2–CA produced the highest vanillin yield of 9.90% for kenaf stalk for 5 wt% of CeZrO2–CA at 160 °C for 30 min. Furthermore, vanillin production using extracted lignin is studied keeping CeZrO2–CA as a catalyst and with the same operating parameters, which yielded 14.3% of vanillin. Afterward, the change in yield with respect to pH is also presented. Finally, the recyclability of catalyst is also studied, which showed that it has a strong metal support and greater stability which may give industrial applications a significant boost.Graphical

Lewis acid/base mediated deep eutectic solvents intensify lignocellulose fractionation to facilitate enzymatic hydrolysis and lignin nanosphere preparation

In this work, Lewis acids (FeCl3, AlCl3) and bases (Na2CO3, Na2SO3) were incorporated into a neutral deep eutectic solvent (DES, choline chloride/glycerin) to intensify the lignocellulose fractionation. The efficiency of fractionation in terms of the maximum delignification rate (89.7 %) and well-pleasing cellulose saccharification (100 %) could be achieved by the Lewis acid-mediated DES. An in-depth insight of the evolution of lignin structure revealed that Lewis acid-mediated DES could cleave the β-O-4 linkages efficiently to achieve a high yield lignin fragments. Meanwhile, the lignin fragments with the enhanced amphiphilic properties facilitate the preparation of lignin nanospheres (LNSs) via the self-assembly process. The resultant LNSs extracted by Lewis acid-mediated DES exhibited an excellent thermal stability, and enhanced antibacterial capacity, which were associated with the phenolic OH content. However, the extracted lignin by Lewis base-mediated DES was mainly attributed to the cleavage of lignin-carbohydrate complexes bond, especially the lignin-carbohydrate ester bond, which retained more ether bonds and a relatively complete structure. This study illuminated the different mechanisms of lignin extraction and the structural evolution of lignin from Lewis acid/base-mediated DES, and provided guidance to select suitable fractionation techniques for upgrading the downstream products.

Green and efficient utilization of beech sawdust waste for sorbitol production: Direct conversion residue via Ru2P/OMC derived from separated lignin

This paper proposes a green and sustainable strategy to achieve efficient utilization of beech sawdust waste to produce sorbitol. First, ethanol dissolution method was used to extract lignin from sawdust. Subsequently, the lignin combined with phloroglucinol were used to fabricate ordered mesoporous carbon (OMC) using solvent evaporation induced self-assembly (EISA) method. Afterwards, Ru2P/OMC was synthesized and utilized as a catalyst for the production of sorbitol from the residue using pure water as green solvent. Finally, the yield of sorbitol and xylitol reached 77.2 % and 12.5 % at 200 °C in 5 h, respectively. Different characterization techniques were used to reveal the structural composition of the catalysts and the mechanism of the reaction. The results show that the bifunctional Ru2P/OMC catalyst has dual activity of hydrolysis and hydrogenation without sulfonation treatments. Interestingly, the bifunctional Ru2P/OMC catalyst has satisfactory activity, selectivity, and stability, which is promising in biomass waste conversion.

Extraction of kraft lignin from waste coconut pith and its application for removal of heavy metal ions from industrial effluent

The Kraft lignin was extracted from waste coconut pith by pulping process. It was characterised by FTIR, XRD, SEM/EDS, TEM, TG/DTG/DSC, BET surface area analyzer and data were linked to their potential application in removal of heavy metal ions. The desorption of metal ions from the surface of Kraft lignin was investigated for efficient re-use. Differential pulse voltammetry (DPV) was used for quantitative study. Adsorption experiment was performed to investigate effects of initial pH, adsorbent dose, contact time, initial concentration and temperature on the adsorption capacity of Kraft lignin. The experimental results demonstrated that metal ion removal using Kraft lignin was a pH-dependent process, with the maximum adsorption capacity at an initial pH of 5-6+0.1. Adsorption was efficient with an adsorbent dosage of 8-10+0.2 mg/mL and temperature at 30+2o C used. Furthermore, the kinetics and equilibrium data are well explained by pseudo-second-order kinetics and the Freundlich adsorption isotherm model at 80 min contact time and 60+0.1 mg/L initial concentration. The best-fit adsorption isotherms and kinetics models were identified using statistical analysis. The thermodynamic parameters of the adsorption process were studied. Moreover, desorption and re-adsorption performance were studied. Kraft lignin still showed good adsorption performance up to six cycles of regeneration.

Integration of carbon capture in a pulp mill—effect of strategic development towards better biomass resource utilization

The pulp and paper industry has an important role in the industrial transition towards net zero or negative emissions, given its renewable biomass-based feedstock and energy supply. In particular, pulp and paper mills have large existing sources of biogenic CO2, with a high potential to contribute to carbon dioxide removal through carbon capture and storage (CCS). To effectively navigate anticipated changes in feedstock and energy markets, there is a need for a better understanding of how different technology pathways for the pulp and paper industry interact with one another, for instance, how enhanced valorization of biomass side streams may affect the potential for carbon capture. This paper aims to investigate the effect of combining carbon capture with lignin extraction in a chemical pulp mill. Pinch analysis is used to study how the targets for heat recovery, fuel usage and electricity generation, are affected by different mill and capture configurations. Based on these results, the effect on carbon flows is evaluated. The results show that when carbon capture technology is implemented and fuel use is minimized at the case-study mill, there is still enough heat available from the recovery boilers to supply the process needs without requiring usage of a utility boiler. However, when carbon capture is combined with lignin extraction, the heat production of the recovery boilers is no longer sufficient to cover the process demands, and additional heat from a utility boiler is required. However, this case implies that some of the carbon leaves the mill embedded in the extracted lignin product, which can be expected to have a higher value than captured carbon dioxide. When back-pressure electricity production was maximized for the different mill configurations, a very high fuel-to-electricity efficiency could be achieved, but since the CO2 emissions from the utility boiler were not assumed to be captured, this would lead to more carbon being emitted compared to the capture scenarios with minimized fuel use.

Switchable Deep Eutectic Solvents for Lignin Dissolution and Regeneration.

Deep eutectic solvents (DESs) are promising for lignin dissolution and extraction. However, they usually possess high polarity and are difficult to recycle. To overcome this drawback, a variety of switchable ionic liquids (SILs) composed of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and alcohols was synthesized and screened. According to the thermodynamic modeling suggestions, the selected DBU-HexOH SIL was coupled with hydrogen-bond donors to form switchable-DES (SDES) systems with moderated viscosity, conductivity, and pH while maintaining switchability. The SDESs produced a well-improved lignin and lignin model compound solubility compared with those of SILs; charging CO2 into SDES (SDESCO2) caused a further increase in solubility. The solubility (25 °C) of syringic acid, ferulic acid, and milled wood lignin in SDESCO2 reached 230.57, 452.17, and 279.12 mg/g, respectively. Such SDES-dissolved lignin can be regenerated using acetone as an anti-solvent. The SDES-regenerated lignin exhibited a well-preserved structure with no noticeable chemical modifications. Furthermore, the SDESCO2 lignin possessed a higher molecular weight (Mw = 10,340 g/mol; Mn = 7672 g/mol), improved uniformity (polydispersity index = 1.35), and a higher guaiacyl lignin unit content compared with the original milled wood lignin. The SDES system proposed in the present work could benefit the fractionation of lignin compounds and facilitate downstream industrial processes.

Impact of Extraction Method on the Structure of Lignin from Ball-Milled Hardwood.

Understanding the structure of hardwoods can permit better valorization of lignin by enabling the optimization of green, high-yield extraction protocols that preserve the structure of wood biopolymers. To that end, a mild protocol was applied for the extraction of lignin from ball-milled birch. This made it possible to understand the differences in the extractability of lignin in each extraction step. The fractions were extensively characterized using 1D and 2D nuclear magnetic resonance spectroscopy, size exclusion chromatography, and pyrolysis-gas chromatography-mass spectrometry. This comprehensive characterization highlighted that lignin populations extracted by warm water, alkali, and ionic liquid/ethanol diverged in structural features including subunit composition, interunit linkage content, and the abundance of oxidized moieties. Moreover, ether- and ester-type lignin-carbohydrate complexes were identified in the different extracts. Irrespective of whether natively present in the wood or artificially formed during extraction, these complexes play an important role in the extractability of lignin from ball-milled hardwood. Our results contribute to the further improvement of lignin extraction strategies, for both understanding lignin as present in the lignocellulosic matrix and for dedicated lignin valorization efforts.

Microwave-assisted ternary deep eutectic solvent pretreatment for improved rice straw saccharification under mild pretreatment conditions

The development of a green and cost-effective pretreatment method to overcome biomass recalcitrance is a challenging assignment for the efficient valorization of lignocellulosic compounds. In this study, a ternary deep eutectic solvent (DES) consisting of choline chloride (ChCl), p-toluene sulfonic acid (pTSA) and ethylene glycol (EG) was applied in rice straw (RS) pretreatment under microwave (MW) irradiation for the further conversion of the polysaccharide fraction. The effect of the pretreatment temperature, time and pTSA content in the DES on lignin extraction and polysaccharide hydrolysis was assessed by a central composite design (CCD). Under the selected pretreatment conditions (80 ºC, 22.5 min, ChCl:pTSA:EG 1:1:9), 61.6% delignification was achieved, as well as nearly complete conversion of the initial glucan in RS (93.4% glucose yield) and a good xylan conversion rate (48.3% xylose yield), representing a total polysaccharide exploitation of 78.3%. Energetical requirement was remarkably lower compared to conventional conductive heating. Importantly, the ternary DES showed good recyclability pattern after two reuses. Overall, this study demonstrated the potential of MW-assisted ternary DES pretreatment for improved valorization of biomass polysaccharides under mild pretreatment conditions, representing an efficient and energetical-saving alternative pathway within the biorefinery framework.

Techno‐economic learning in biorefinery research; a meta‐level perspective of three exemplary cases

AbstractThe production of liquid fuels and chemicals from biomass is an essential part of establishing a bioeconomy. Numerous techno‐economic studies have been published on different pathways for processing biomass. To examine the progress made in this field, a meta‐analysis investigating three exemplary biobased products was conducted. Using recently published techno‐economic studies, the (average) unit production costs for biodiesel, cellulosic ethanol and kraft lignin were investigated. Findings in this study are based on an understanding of two phenomena: economies of scale and the learning effect. Economies of scale can be observed for each case, with kraft lignin extraction indicating the greatest cost advantages and the production of biodiesel the smallest. The investigation of potential learning effects revealed by the data yielded unexpected results: In two out of three cases, the calculated average unit production cost was observed to increase over time. These results contradict the expected influence of learning effects on calculated unit production costs as these did not decrease over time for a specific technology. A closer investigation of processing pathways and feedstocks shows that a diversification in research has occurred over the last three decades. Different driving forces of innovation related to the investigated products are also identified.

Lignin Use in Enhancing the Properties of Willow Pellets

Shrub willow (Salix spp.) is an emerging lignocellulosic biomass utilized in fuel pellets as an energy source. However, improvements are needed to increase the efficacy of pellets in areas such as the energy content, durability, and hazardous carbon monoxide emissions. This study examined the effect of utilizing lignin as an additive on willow pellet properties. Two types of lignin were used in individual treatments: lignin recovered from the hot water extraction of willow (RecL) and commercial softwood kraft lignin (ComL). A statistical analysis of the ash content, energy content, bulk density, durability, pellet length, moisture absorption, and carbon monoxide emissions for the pellets with and without the addition of RecL or ComL lignin was conducted. The observed significant reduction in carbon monoxide emissions from RecL pellets was an important effect of the lignin addition. There were also significant increases in the energy content, bulk density, and durability of lignin-added pellets. While the production of carbon monoxide via pellets continues to be explored, lignin can be utilized as an additive to reduce carbon monoxide emissions and simultaneously improve other pellet properties.

Isolation of nanocellulose from Dodonaea viscosa plant: structural and thermal properties

Abstract In this research work, cellulose was isolated from Dodonaea viscosa plant by means of various chemical processes followed by the preparation of nanocellulose through sulfuric acid hydrolysis. These chemical processes begin with the removal of non-cellulosic material such as lignin, pectin, crude wax, and hemicellulose followed by alkaline treatment and chlorine-free bleaching methods. Fourier transform infrared (FTIR) spectroscopy showed the successful isolation of cellulosic material after removing hemicellulose, lignin, and other extractives. Thermogravimetric analysis (TGA) elucidated the thermal degradation profile of the cellulose-based materials obtained after various chemical procedures at each step. Additionally, nanocellulose was prepared from cellulosic material using acid hydrolysis, and its structural and thermal properties were discussed. Nanocellulose extraction from the lignocellulosic biomass sources and its further utilization has been the subject of intensive research as the global community needs the use of green chemistry principles in recent life. Nanocellulosic material due to its unique characteristics and properties is of great importance and has many applications in various industries, including materials science and engineering.

A STUDY OF CELLULOSE AND LIGNIN EXTRACTED FROM SĀNCI BARK AND THEIR MODIFICATION

Numerous studies have been carried out regarding different early and medieval writing bases like papyrus, birch bark, parchment, and Tālpātra. The quality of plant-derived manuscript writing bases has been aided by the presence of cellulose and lignin in plant cell walls. Sāncipāt, a popular writing base in early and medieval Assam, India, has not yet been thoroughly studied in this regard. In this paper, a scientific attempt has been made to reveal the physicochemical and mechanical properties of cellulose and lignin fibre in Sāncipāt. Various analytical techniques, including FTIR, P-XRD, TEM, UTM, were employed to characterize the cellulose fibres and lignin extracted from both old and new Sāncipāt, as well as their modified forms. A comparative analysis was made between the old and new bark samples of both cellulose fibres and lignin, and the general conclusions drawn from this work can be attributed to structural, thermal, and morphological changes of both cellulose fibres and lignin with degradation and decomposition, accompanied by ageing. The structural and chemical compositions of the extracted samples from the old and new barks were found to be almost identical, indicating only some minor degradation. While FTIR and UV spectroscopic analyses of the samples confirmed the successful extraction of cellulose fibres and lignin, electron microscopy and X-ray diffraction techniques allowed observing the structural and morphological changes that had occurred in the old bark samples as a result of ageing. Thermal stability studies and tensile strength measurements were also carried out to investigate the mechanical properties of the old and new bark samples.

Green and sustainable production of high-purity lignin microparticles with well-preserved substructure and enhanced anti-UV/oxidant activity using peroxide-promoted alkaline deep eutectic solvent

Deep eutectic solvents (DESs) have emerged as promising and eco-friendly solvents for the efficient extraction of lignin from biomass due to their low cost and environmental benefits. Nevertheless, the prevalent use of acidic DESs in lignin extraction often results in excessive depolymerization and recondensation of lignin, thereby impeding its downstream applications. In this study, we developed a range of alkaline DESs (ADESs), both pure and peroxide-containing, for the extraction of high-quality lignin from bamboo. Moreover, carbon dioxide (CO2) was employed for the precipitation and regeneration of the extracted lignin. The obtained lignin fractions were comprehensively characterized in terms of yield, purity, morphology, solubility, structural features, and anti-UV/oxidant activity. The results showed that the monoethanolamine-based ADES demonstrated superior performance among the pure ADESs. Structural analysis confirmed the well-preserved substructures of lignin fractions obtained using ADESs, with β-O-4 bond retention ranging from 49.8 % to 68.4 %. The incorporation of a suitable amount of peroxide improved lignin yield, morphology, solubility, and anti-UV/oxidant activity. Additionally, the anti-UV/oxidant activity of lignin exhibited a positive correlation with its phenolic hydroxyl content. This study provides a valuable reference for the green and sustainable production and valorization of lignin within the existing biorefinery framework.

Correction: Lignin extraction from sawdust: optimization of experimental studies, computer-aided simulation and techno-economic analysis of scale-up process design with uncertainty quantification

Correction: Lignin extraction from sawdust: optimization of experimental studies, computer-aided simulation and techno-economic analysis of scale-up process design with uncertainty quantification

Extraction of lignin from sugarcane trash and its potency as biosurfactant

Sugarcane trash (SCT) is an environmental concern in Indonesia. The chemical compositions of SCT can be used as benign materials, such as lignin-based biosurfactants, for improving enzymatic hydrolysis performance through the biorefinery concept, yet no one has worked on this. Therefore, the crux of this study is to evaluate lignin and lignin-based biosurfactant characteristics from two different acid-alkali extraction methods: microwave (SCT-A) and autoclave (SCT-B). Both extraction methods successfully isolated lignin with a total lignin content of 82 % and 25 % for SCT-A and 73 % and 35 % for SCT-B, respectively. Lignin was successfully processed into biosurfactant by grafting method, which was proved by ester groups in biosurfactants at 1700 cm−1 from FTIR and δC 163.9–164.4 ppm from 13C NMR. Lignin-based SCT-A can reduce water surface tension up to 50.2 mN/m from 58.8 mN/m (pure water), while the lignin-based SCT-B was 54.4 mN/m. Further studies are required to evaluate the effectiveness of lignin-based biosurfactants in enzymatic hydrolysis.

Effect of solvent and acid catalyst selection on lignin recovery and purity in autoclave-assisted organosolv extraction

This study leverages the autoclave-assisted method to explore a range of acid catalysts (H2SO4, HCl, HNO3, H3PO4) and solvents (methanol, ethanol, acetone, 2-butanol, 2-propanol) for lignin extraction, with a focus on identifying optimal efficiency-enhancing combinations. By contrasting the performance of various acid catalysts and solvents, this work transcends previous efforts in this field. Notably, H2SO4 yields the highest lignin recovery (44.7 %) but with lower purity (78.4 %) compared to HCl (85.7 %) in the same solvent. Methanol yields the highest recovery (45.1 %), yet lower purity (79.2 %) than ethanol (85.7 %) with a similar catalyst. A pivotal improvement lies in the elucidation of structural purity, substantiated by IR and NMR resulting signals, supported by microscale morphology and chemical composition (SEM-EDX). This study extends current understanding, providing profound insights into optimizing extraction procedures for producing lignin with desired attributes.

Extraction and Isolation of Different Lignins from Sugarcane Bagasse Biomass and Its Subsequent Thermal Degradation to Renewable Fuels

Extraction and Isolation of Different Lignins from Sugarcane Bagasse Biomass and Its Subsequent Thermal Degradation to Renewable Fuels

Recent advances in biorefineries based on lignin extraction using deep eutectic solvents: A review

Considering the urgent need for alternative biorefinery schemes based on sustainable development, this review aims to summarize the state-of-the-art in the use of deep eutectic solvent pretreatment to fractionate lignocellulose, with a focus on lignin recovery. For that, the key parameters influencing the process are discussed, as well as various strategies to enhance this pretreatment efficiency are explored. Moreover, this review describes the challenges and opportunities associated with the valorization of extraction-derived streams and highlights recent advancements in solvent recovery techniques. Furthermore, the utilization of computational models for process design and optimization is introduced, as the initial attempts at the economic and environmental assessment of this lignocellulosic bioprocess based on deep eutectic solvents. Overall, this review offers a comprehensive perspective on the recent advances in this emerging field and serves as a foundation for further research on the potential integration of deep eutectic pretreatment in sustainable multi-product biorefinery schemes.

Aspergillus niger Improves the Nutritional Composition of Apple Pomace by Solid-State Fermentation

The effect of solid-state fermentation using Aspergillus niger on the nutritional composition of apple pomace was investigated in this study. Apple pomace was milled to 2 mm and sterilized at 121 °C for 15 min before fermentation. Aspergillus niger strain (ATCC 200345) was cultured and inoculated to apple pomace 104 spores/ml. Raw and fermented apple pomace were analyzed for determination of the crude protein (CP), ash, ether extract (EE), crude fiber (CF), neutral-detergent fiber (NDF), acid-detergent fiber (ADF), and acid-detergent lignin (ADL) content. The CP (P

Sustainable Biomass Lignin-Based Hydrogels: A Review on Properties, Formulation, and Biomedical Applications.

Different techniques have been developed to overcome the recalcitrant nature of lignocellulosic biomass and extract lignin biopolymer. Lignin has gained considerable interest owing to its attractive properties. These properties may be more beneficial when including lignin in the preparation of highly desired value-added products, including hydrogels. Lignin biopolymer, as one of the three major components of lignocellulosic biomaterials, has attracted significant interest in the biomedical field due to its biocompatibility, biodegradability, and antioxidant and antimicrobial activities. Its valorization by developing new hydrogels has increased in recent years. Furthermore, lignin-based hydrogels have shown great potential for various biomedical applications, and their copolymerization with other polymers and biopolymers further expands their possibilities. In this regard, lignin-based hydrogels can be synthesized by a variety of methods, including but not limited to interpenetrating polymer networks and polymerization, crosslinking copolymerization, crosslinking grafted lignin and monomers, atom transfer radical polymerization, and reversible addition-fragmentation transfer polymerization. As an example, the crosslinking mechanism of lignin-chitosan-poly(vinyl alcohol) (PVA) hydrogel involves active groups of lignin such as hydroxyl, carboxyl, and sulfonic groups that can form hydrogen bonds (with groups in the chemical structures of chitosan and/or PVA) and ionic bonds (with groups in the chemical structures of chitosan and/or PVA). The aim of this review paper is to provide a comprehensive overview of lignin-based hydrogels and their applications, focusing on the preparation and properties of lignin-based hydrogels and the biomedical applications of these hydrogels. In addition, we explore their potential in wound healing, drug delivery systems, and 3D bioprinting, showcasing the unique properties of lignin-based hydrogels that enable their successful utilization in these areas. Finally, we discuss future trends in the field and draw conclusions based on the findings presented.