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The development of strategies allowing either the production of high value phenolics, or the isolation of properties‐enhanced materials from technical lignins represents a fundamental step in the industrial upcycling of technical lignins. Both aims are met by the strategy presented in the present work, relying on the coupling of solvent‐based fractionation with the oxidative action of a new type of alkaline‐stable genetically modified bacterial laccase. The described approach succeeded in the tandem, high‐yield and selective isolation of valuable lignin‐monomeric compounds (MCs) and high molecular weight and hydrophobicity‐tailored polymerised materials (PMs) from two technical lignins, namely softwood kraft lignin (SKL), and wheat straw organosolv lignin (WSL). With respect to MCs, higher yields as compared to similar studies (up to 17.2 mg/g) were achieved. PMs from SKL samples where characterised by an almost quadrupled Mw, while in the case of WSL the Mw was approximately doubled. Noteworthy, the reaction conditions were optimized in terms of reaction temperature, time, enzymatic loading, and alkalinity for the selective production of single MCs. Most interestingly, technical lignins as well as their fractions and the PMs deriving from their laccase‐catalysed oxidation showed increased hydrophobicity. [ABSTRACT FROM AUTHOR]

Lignin fractionation aims at dividing the original lignin material into more uniform fractions that have the qualities desired for further processing of the material. Solvent fractionation is a versatile method that produces a soluble and an insoluble fraction with varying compositions, including molecular weight distribution, polydispersity (PDI), and phenolic hydroxyl (OHph) content. These properties are key factors in the further downstream applicability of lignin. Kraft, organosolv, and hydrolysis lignins were fractionated using multiple solvents and their water solutions with a single-stage fractionation protocol. The produced fractions were analyzed for their molecular size distribution and OHph content. Soluble fractions were discovered with desirable qualities, including a narrow size distribution (lowest PDI 1.4) and accumulation of OHph groups (up to 3.05 mmolOH/glignin). Three fractionation solvents, i.e., pure isopropanol, pure ethanol, and 30% γ-valerolactone, were found to produce solvent-specific soluble fractions that had relatively identical characteristic Mw, Mn, and PDI values regardless of the initial lignin material. This is crucially important new data that is beneficial for robust lignin applicability at industrial scale. Other important observations were made regarding water-alcohol solutions, as the increase in initial solid content resulted in changes in the composition of the fractions produced. Further applicability of the obtained fractions is examined in this paper. Patterns as well as differences between the three lignin materials were observed in their dissolution and the resulting compositions of the soluble fractions. This wide comparable dataset of industrially relevant solvents and lignin materials provides significant insight into the possibilities of lignin downstream processing. [ABSTRACT FROM AUTHOR]

Lignin, an abundant renewable biopolymer found in plant cell walls, is enriched in phenolic units within its complex molecular structure. Unlocking its potential as alternative feedstock in (bio)refining has posed a long-standing challenge, even though it holds immense promise for replacing fossil-derived phenolic and aromatic compounds. This study focuses on fast pyrolysis as effective thermochemical depolymerization method of lignin, coupled with the in situ catalytic upgrading aiming to produce valuable bio-oil enriched in dealkoxylated (alkyl)phenolic and aromatic compounds. Lignin was isolated via the organosolv process from beechwood sawdust (hardwood biomass). Various acidic aluminosilicate catalysts (e.g., zeolites, such as ZSM-5, Beta and USY, and amorphous silica alumina) were applied, having different Si/Al ratio, porous and acidic properties. Fast pyrolysis experiments were conducted on a fixed-bed bench-scale reactor at two distinct temperatures (500 and 600 °C), employing different contact times and lignin-to-catalyst ratios. Non-catalytic pyrolysis experiments revealed that higher temperature, significantly influences bio-oil’s composition and yield, resulting in the conversion of initially formed alkoxy-phenols to alkyl-phenolic compounds, reaching a 47% relative concentration at 600 °C, while also yielding high amount of bio-oil up to 43 wt%. Among the catalysts tested, zeolite ZSM-5 (Si/Al=40) proved to be the most efficient, shifting the chemical profile of bio-oil from phenolic to aromatic (mainly BTX) with relative concentration of 57%, owing to its unique microporous structure and acidity. Depending on the catalyst type, a balance between BTX monomer aromatics and naphthalenes was observed. Lignin, as well as the obtained products (bio-oil, non-condensable gases, char/coke-on-catalyst) were thoroughly characterized using various analytical techniques. The catalytic upgrading results were associated with the physicochemical properties of the catalysts, providing valuable insights into the underlying reaction mechanisms.

To fully utilize the aromatic ring structure of lignin and realize high value addition, organosolv lignin (OL) extracted from papermaking waste liquid was subjected to catalytic pyrolysis for the production of phenolic compounds. Using self-made carbon nanospheres as a template, cellular La0.8Pr0.2NiO3 perovskite was prepared by the sol-gel method and used as catalyst in the pyrolysis of OL at 600 °C for 3 h. The yield of liquid-phase product was 21.34 %, and the selectivity of phenolic compounds reached 70.20 %, constituting increases by 43.41 % and 25.87 % compared with the yield and selectivity of the catalyst-free process, respectively. After four cycles of regeneration, La0.8Pr0.2NiO3 perovskite still demonstrated good structural and catalytic stability. This work provides a theoretical basis for the development of green and sustainable chemical products.

Lignin, the second most abundant biopolymer on earth and with a predominantly aromatic structure, has the potential to be a raw material for valuable chemicals and other bio‐based chemicals. In industry, lignin is underutilized by being used mostly as a fuel for producing thermal energy. Valorization of lignin requires knowledge of the structure and different linkages in the isolated lignin, making the study of structure of lignin important. In this article, lignin samples isolated from two types of reactors (autoclave reactor and displacement reactor) were analyzed by FT‐IR, size exclusion chromatography, thermogravimetric analysis (TGA), and Py‐GC‐MS. The average molecular mass of the organosolv lignins isolated from the autoclave reactor decreased at higher severities, and FT‐IR showed an increase in free phenolic content with increasing severity. Except for molecular mass and molecular mass dispersity, there were only minor differences between lignins isolated from the autoclave reactor and lignins isolated from the displacement reactor. Carbohydrate analysis, Py‐GC–MS and TGA showed that the lignin isolated using either of the reactor systems is of high purity, suggesting that organosolv lignin is a good candidate for valorization. [ABSTRACT FROM AUTHOR]

This study aimed to conduct a comprehensive Life Cycle Assessment (LCA) of lignin-based polyol production through organosolv fractionation of cardoon stalks and subsequent lignin liquefaction. The LCA employed a cradle-to-gate approach, encompassing cardoon cultivation and all processing steps leading to polyol production. The research involved laboratory-scale optimization of the organosolv and liquefaction processes, followed by industrial-scale implementation. The analysis revealed that all stages of the production chain, including crop cultivation, organosolv, and liquefaction, significantly influenced overall environmental impacts. Specific materials and processes played pivotal roles, such as harvesting machinery and fertilizers in crop production, γ-Valerolactone (GVL) as the primary contributor (72–100%) to environmental impacts in the organosolv phase, and materials like polyethylene glycol 400 (PEG 400) and glycerin in the liquefaction phase, accounting for the majority (96–100%) of environmental impacts in this stage. When considering endpoint damage categories, it became evident that this production chain had a notable impact on human health, primarily due to emissions in air, water, and soil from agricultural processes. Lignin-based polyols demonstrated a moderate improvement compared to their petroleum-based counterparts, with an approximate reduction of 3–16% in environmental impact. [ABSTRACT FROM AUTHOR]

Organosolv lignin nanoparticles have been recently evaluated for their use in mineral froth flotation as a flotation reagent, and as a result, the recovery of the target minerals was improved and the selectivity of the process was increased. However, the mechanism of lignin activity in mineral froth flotation is not known. Therefore, this study is the first step in understanding the interaction of organosolv lignin with the mineral surface. As such, the organosolv lignin was characterized by GPC and 31P NMR, where the structural differences between the birch and spruce lignins were determined. The molecular size and lignol unit composition were evaluated. Subsequently, the morphology and size of the organosolv lignin particles were examined for all 4 produced types: BN, BM, SN, and SM. The ζ potential was measured in the pH range of 2–11. All particles had a high negative charge, which indicated good stability of the dispersion in the alkali range. The stability of their colloidal dispersion was observed under increasing concentrations of mono- and divalent cations, and electrostatic repulsion was identified as the main stabilization mechanism. Finally, QCM-D was used to study the interaction of the lignin particles with the mineral surfaces of chalcopyrite, pyrite, and galena, which gave insight into the possible mechanism during the flotation process. [ABSTRACT FROM AUTHOR]

When optimizing the process parameters of the acidic ethanolic organosolv process, the aim is usually to maximize the delignification and/or lignin purity. However, process parameters such as temperature, time, ethanol and catalyst concentration, respectively, can also be used to vary the structural properties of the obtained organosolv lignin, including the molecular weight and the ratio of aliphatic versus phenolic hydroxyl groups, among others. This review particularly focuses on these influencing factors and establishes a trend analysis between the variation of the process parameters and the effect on lignin structure. Especially when larger data sets are available, as for process temperature and time, correlations between the distribution of depolymerization and condensation reactions are found, which allow direct conclusions on the proportion of lignin's structural features, independent of the diversity of the biomass used. The newfound insights gained from this review can be used to tailor organosolv lignins isolated for a specific application. [ABSTRACT FROM AUTHOR]

The focus of the research was to evaluate the use of lignin from different sources as an agent for the removal of diverse types of microplastics when present in wastewater. Organosolv lignin was obtained from three different sources (Miscanthus sp., pine bark and solid anaerobic digestates from Organic Fraction of Municipal Solid Wastes) by an ethanol-based organosolv treatment carried out in a pressurized stirred-tank reactor. The lignins obtained were evaluated as an adsorbent for diverse types of microplastics: High-density polyethylene (HDPE), Polystyrene (PS), Expanded Polystyrene (EPS), and Polypropylene (PP). All lignins used had the capacity to capture plastic particles from all plastic types, but a differential absorbance potential was found both for plastic types and lignin samples. EPS was the least adsorb type for all lignin sources, with the remaining plastics presenting equivalent results. Pine bark lignin was the best adsorbent among the tested feedstocks, always presenting the best performance for all plastic types. The direct utilization of organosolv hydrolysates, avoiding lignin recovery presented a similar behaviour. These results open the possibility to develop new natural, plant-based, adsorbents for microplastic removal from contaminated wastewater. [ABSTRACT FROM AUTHOR]

Abstract When optimizing the process parameters of the acidic ethanolic organosolv process, the aim is usually to maximize the delignification and/or lignin purity. However, process parameters such as temperature, time, ethanol and catalyst concentration, respectively, can also be used to vary the structural properties of the obtained organosolv lignin, including the molecular weight and the ratio of aliphatic versus phenolic hydroxyl groups, among others. This review particularly focuses on these influencing factors and establishes a trend analysis between the variation of the process parameters and the effect on lignin structure. Especially when larger data sets are available, as for process temperature and time, correlations between the distribution of depolymerization and condensation reactions are found, which allow direct conclusions on the proportion of lignin's structural features, independent of the diversity of the biomass used. The newfound insights gained from this review can be used to tailor organosolv lignins isolated for a specific application.

Despite lignin's global abundance and its use in biomedical studies, our understanding of how lignin regulates disease through modulation of cell morphology and associated phenotype of human cells is unknown. We combined an automated high-throughput image cell segmentation technique for quantitatively measuring a panel of cell shape descriptors, droplet digital Polymerase Chain Reaction for absolute quantification of gene expression and multivariate data analyses to determine whether lignin could therapeutically modulate the cell morphology and phenotype of inflamed, degenerating diseased human cells (osteoarthritic (OA) chondrocytes) towards a healthier cell morphology and phenotype. Lignin dose-dependently modified all aspects of cell morphology and ameliorated the diseased shape of OA chondrocytes by inducing a less fibroblastic healthier cell shape, which correlated with the downregulation of collagen 1A2 (COL1A2, a major fibrosis-inducing gene), upregulation of collagen 2A1 (COL2A1, a healthy extracellular matrix-inducing gene) and downregulation of interleukin-6 (IL-6, a chronic inflammatory cytokine). This is the first study to show that lignin can therapeutically target cell morphology and change a diseased cells' function towards a healthier cell shape and phenotype. This opens up novel opportunities for exploiting lignin in modulation of disease, tissue degeneration, fibrosis, inflammation and regenerative medical implants for therapeutically targeting cell function and outcome. [ABSTRACT FROM AUTHOR]

In this work, a detailed study on the ethanosolv lignin fractionation from endocarps, aiming at understanding the role played by the ball milling (BM) pretreatment, is presented. Walnut and pistachio shells were chosen as a case study, since they exhibit excellent mechanical properties and their tissues have been extensively studied in terms of structure, composition, and lignin distribution. Here, it was demonstrated that the BM pretreatment is not particularly suited for these biomasses, since it is not able to promote the lignin fractionation from the whole tissue, and additionally, it triggers the oxidation of the substrate. Although in the case of walnut shell this oxidation can be prevented thanks to the remarkable radical scavenger activity (RSA) of its extractives, in the case of pistachio shell the BM is responsible for a partial lignin condensation. Pistachio shells resulted a particularly attractive feedstock since they can be easily delignified using mild ethanosolv processes, leading to highly regular lignin fractions, rich in S units (86%) and β-O-4 linking motif (>60% C9 units), so particularly suited for the chemical upgrading to added-value aromatics.

In an effort to achieve sustainable development goals, a reevaluation of the materials used in wooden buildings must be done, including the preservatives used to treat the materials. Since typical wood preservatives use toxic heavy metals, their handling and use can contaminate the environment. Therefore, substances such as lignin-derived components have been investigated as bio-based preservatives. Organosolv treatment is a promising technique for separating components of lignocellulosic biomass, which enables the utilization of each component. The present report describes components of lignocellulose with antifungal effects that were recovered after organosolv treatment using water and 1-butanol solvent at 473 K for 2 h, followed by simple solvent fractionation. The organosolv lignin was divided into three fractions: n -hexane soluble, ethyl acetate soluble, and ethyl acetate insoluble, yielding 23 wt%, 52 wt% and 13 wt%, respectively. Antifungal activity was determined using an agar plate method. White rot fungi (Trametes versicolor) was dispersed on the agar plate with a cellulose disc containing each lignin-derived fraction obtained from Japanese cedar. Results showed inhibition of fungal growth over the cellulose disc containing the n -hexane soluble fraction. To examine the effect in greater detail, the chemical structure of the n -hexane-soluble fraction on the antifungal activity was investigated. The content of phenolic hydroxyl group in n -hexane-soluble fraction was the highest (4.6 mmol/g), and the results from the chemical modification suggested that the functional group was required for antifungal action. In addition, the n -hexane-soluble fraction imparted some water resistance. The procedures used for cedar as a feedstock were applied to another type of biomass—bagasse—and its fractions showed antifungal activity similar to those of Japanese cedar. [Display omitted] • Antifungal fraction was recovered by organosolv followed by solvent fractionation. • Cellulose disc containing the n -hexane soluble fraction inhibited fungal growth. • Phenolic hydroxyl group in the fraction was required for antifungal action. • N -hexane-soluble fraction imparted some water resistance property. • The fractions derived from Japanese cedar and bagasse showed the similar activity. [ABSTRACT FROM AUTHOR]

The effects of ZrO 2 and TiO 2 incorporated into Fe 2 O 3 matrix on oxidative cracking of degraded lignin and on the acid-base properties were investigated. After lignin degradation, cracking into lower-molecular-weight products was greatest using ZrO 2 -FeO X. Reactivity of the lattice oxygen was evaluated using H 2 -TPR, which revealed that the reactivity was improved. Thus, ZrO 2 -FeO X promoted oxidative decomposition of lignin to oligomers. In the cracking of 2-methoxyphenol, TiO 2 -FeO X and ZrO 2 -FeO X resulted in a 5- to 6-fold greater yield of phenol than the yield over Fe 2 O 3. According to Mulliken population analysis, the charge density difference between Fe-O increased by ca. 12% in TiO 2 -FeO X and ZrO 2 -FeO X as compared with Fe 2 O 3. This result suggests that addition of TiO 2 and ZrO 2 improved the acid-base properties of the catalyst, which promoted demethoxylation of 2-methoxyphenol. Thus, ZrO 2 -FeO X enhanced oxidative decomposition using its lattice oxygen that converted degraded lignin into lower molecule oligomers, followed by demethoxylation to produce phenol. [Display omitted] • Catalytic cracking of degraded lignin over FeO X -based catalysts was investigated. • Lignin degradation was caused by oxidative decomposition via the lattice oxygen. • The addition of TiO 2 and ZrO 2 into Fe 2 O 3 improved the acid-base properties. • ZrO 2 -FeO X promoted the synergistic conversion to phenol from degraded lignin. [ABSTRACT FROM AUTHOR]

In this work, a detailed study on the ethanosolv lignin fractionation from endocarps, aiming at understanding the role played by the ball milling (BM) pretreatment, is presented. Walnut and pistachio shells were chosen as a case study, since they exhibit excellent mechanical properties and their tissues have been extensively studied in terms of structure, composition, and lignin distribution. Here, it was demonstrated that the BM pretreatment is not particularly suited for these biomasses, since it is not able to promote the lignin fractionation from the whole tissue, and additionally, it triggers the oxidation of the substrate. Although in the case of walnut shell this oxidation can be prevented thanks to the remarkable radical scavenger activity (RSA) of its extractives, in the case of pistachio shell the BM is responsible for a partial lignin condensation. Pistachio shells resulted a particularly attractive feedstock since they can be easily delignified using mild ethanosolv processes, leading to highly regular lignin fractions, rich in S units (86%) and β-O-4 linking motif (>60% C9 units), so particularly suited for the chemical upgrading to added-value aromatics. [ABSTRACT FROM AUTHOR]

As the most important phenolic biopolymer in nature, lignin shows promising application potentialities in various bioactivities in vivo and in vitro, mainly including antioxidant, anti-inflammatory, hypolipidemic, and antidiabetic control. In this work, several carbon-based solid acids were synthesized to catalyze the fragmentation of organosolv lignin (OL). The generated lignin fragments, with controllable molecular weight and functional groups, were further evaluated for their application in the prevention and treatment of type 2 diabetes mellitus (T2DM). The results suggested that the urea-doped catalyst (SUPC) showed a more excellent catalytic performance in producing diethyl ether insoluble lignin (DEIL) and diethyl ether soluble lignin (DESL). In addition, the lignin fragments have a good therapeutic effect on the cell model of T2DM. Compared with the insulin resistance model, DEIL obtained by catalytic depolymerization of OL with SUPC could improve the glucose consumption of insulin-resistant cells. Moreover, low-concentration samples (50 μg/mL) can promote glucose consumption (19.7 mM) more than the traditional drug rosiglitazone (17.5 mM). This work demonstrates the prospect of depolymerized lignin for the prevention and treatment of T2DM and provides a new application field for lignin degradation products. [ABSTRACT FROM AUTHOR]

While lignin holds potential as a sustainable source for fuels and chemicals, it faces hurdles due to its large molecular size, low heating values, and high oxygen content. In this study, the reductive depolymerization of organosolv lignin was investigated using mono-/bimetallic carbon-supported catalysts. At 340 °C, the MoRu/AC catalyst significantly reduced organosolv lignin feed's molecular weight from 2600 to 460 g/mol, yielding ∼70 % depolymerized organosolv lignin with a higher heating value of 32.92 MJ/kg, mainly composed of substituted phenolic compounds/aromatic hydrocarbons. Conversely, the MoRu/ACP catalyst underperformed, possibly due to residual acidity triggering undesirable side reactions like condensation. Thorough investigations revealed that introducing Mo into Ru catalysts significantly influences the hydrodeoxygenation process, resulting in H/C and O/C ratios of 1.29 and 0.20, contrasting with the initial feed's 1.05 and 0.35 ratios. Furthermore, density functional theory calculations showed lower energy barriers for breaking Caryl−OH/Caryl−O* bonds in guaiacol, a model compound, due to MoRu interactions, implying a promising deoxygenation potential for organosolv lignin transformation. The successful production of high-value bio-oil from technical lignin using the MoRu catalyst showcases its potential to pave the way toward carbon neutrality by offering eco-friendly alternatives to traditional fossil fuels and chemicals. [Display omitted] • MoRu/AC catalyst showed a remarkable reduction in OL M w , ∼2600 vs. 460 g/mol. • MoRu/ACP catalyst exhibited inferior performance in HDO due to residual acidity. • Mo incorporation into the Ru/AC catalyst impacted HDO, favoring H/C and O/C ratios. • At 340 °C, using MoRu/AC yielded ∼70 % DOL, comprising substituted phenolic compounds. • MoRu reduced the energy barrier for breaking Caryl−OH/Caryl−O* bonds compared to Ru. [ABSTRACT FROM AUTHOR]

[Display omitted] • OLP's were able to replace 70% of TOFA and improve recovery. • Higher recovery (+2%) and small decrease in grade (−0.3 %) in rougher-cleaner tests. • Visually, more stable froths were formed when OLP was added with TOFA. • Small difference in zeta potential and FTIR peaks may indicate weak OLP attachment. Beneficiation of the tailings from Iron Oxide Apatite (IOA) ore has become an important topic in the field of mineral processing as phosphate rock is considered as critical raw material by the European Union. Driven by the strong call for sustainability and green technology, this paper introduces the application of novel and bio-based organosolv lignin particles (OLP) as a reagent for apatite flotation. In the artificial mineral mixture flotation tests, OLP addition or replacement to tall oil fatty acid-based collector (TOFA) was shown to improve flotation kinetics and recovery. In this study, it was demonstrated that one of the widely used commercial TOFA collectors could be replaced with OLP by 70 %. The replacement led to an increase in recovery (+2%) and only a minimal decrease in P grade (−0.3 %) for the rougher-cleaner flotation tests in one of the two feed types tested. The influence of OLP and other reagents on apatite floatability has been investigated through Hallimond tube tests and laboratory scale batch flotation tests as well as zeta potential measurements and spectroscopy tests to further understand the possible mechanism and synergism of reagents in the apatite flotation system. [ABSTRACT FROM AUTHOR]

Lignin is a promising alternative to petrochemical precursors for conversion to industrial-needed products. Organosolv lignins were extracted from different agricultural wastes including sugarcane bagasse (BG) and trash (ST), corncob (CC), eucalyptus wood (EW), pararubber woodchip (PRW), and palm wastes (palm kernel cake (PKC), palm fiber (PF), and palm kernel shell (PKS), representing different groups of lignin origins. Physicochemical characteristics of lignins were analyzed by several principal techniques. Most recovered lignin showed high purity of >90 % with trace sugar contamination, while lower purities were found for lignin from palm wastes. Hardwood lignins (EW and PRW) mainly contained guaiacyl (G) and syringyl (S) units with a minor fraction of p -hydroxyphenyl units (H) with high molecular weight, glass transition temperature, phenolic hydroxy group and low aliphatic hydroxy group. Grass-type lignins (BG, ST, CC) and palm lignins (PKC, PF, and PKS) contained three monolignols of H, G, and S units with lower molecular weights and C 5 -substituted hydroxy of S unit. Among the grass-type lignins, PKC lignin contained the highest nitrogen and lipophilic components with the lowest molecular weight, thermal stability, and glass transition temperature. This provides insights into properties of organosolv lignin as basis for their further applications in chemical, polymer and material industries. [Display omitted] • Ethanosol v process with 70 % v /v ethanol and H 2 SO 4 at 170 °C for 60 min was developed. • Properties of organosolv lignins from different agricultural wastes were analyzed. • Lower phenolic-OH content of PKC lignin led to lower Mw, Tg, and thermal stability. • Lipid and nitrogen content of lignins were observed by 31P NMR and pyrolysis-GC/MS. • Lignins for application in chemical, polymer and material industry were considered. [ABSTRACT FROM AUTHOR]

Several lignin samples of varying botanical nature (softwood, hardwood, or annual plants) and extraction procedures (Kraft, Organosolv, or soda) were fully characterized by complementary techniques and engaged in "catalyst-free" depolymerization in air under basic conditions. Treatment of the complex reaction mixture was optimized to ensure reproducibility, careful analyses, and accurate data. After an optimization of the reaction conditions, we were able to recover high amounts of aromatic compounds (up to 19%wt). Additionally, we demonstrated a relation between lignin's structure, i.e., the accessible phenol moieties and inter-unit linkages, and the yields of aromatic compounds, thus showing the importance of the extraction process to optimize lignin's potential. This work provides valuable reference for developing further lignin depolymerization under basic media. [ABSTRACT FROM AUTHOR]

Lignosulfonate (LS), kraft lignin (KL), and organosolv lignin (OL) were evaluated as potential modulating agents of the physicochemical properties of Port wine at two different concentrations for 7 and 30 days. KL and LS demonstrated the ability to remove proteins and potentiate the anthocyanin concentration. LS reduced the tannin content and the interaction of salivary acidic proline-rich proteins with wine phenolic compounds. None of the lignin promoted a perceptible color change; however, the yellowish color of KL and OL at 100 g/hL contributed to an increase in the yellow tones of wines. Lignin improved wine aroma by reducing the amount of unwanted volatiles by 30% and increasing the content of ethyl esters associated with fruity aromas by up to 60%. The results suggest that lignin, especially LS, can be employed as a modulating agent, positively impacting wine's physicochemical properties. This valorization of a byproduct opens up new opportunities for the wine industry.

The autocatalyzed ethanolic organosolv process is gaining increasing attention for the sulfur-free isolation of lignin, which is subsequently used as a renewable substitute for various fossil-based applications. For the first time, the mechanochemical influence of seven different particle sizes of two different biomasses on the respective organosolv lignin structure is examined. Wine pruning (Pinot Noir) and wine pomace (Accent) are used for organosolv process with particle sizes ranging from 2.0-1.6 mm to less than 0.25 mm. As particle size decreases, the weight-average molecular weight increases, while the total phenol content decreases significantly. Additionally, the distribution of the lignin-typical monolignols and relevant substructures, as determined by two-dimensional heteronuclear nuclear magnetic resonance spectra single quantum coherence (HSQC), is observed. The degree of grinding of the biomass has a clear chemical-structural influence on the isolated HG and HGS organosolv lignins. Therefore, it is crucial to understand this influence to apply organosolv lignins in a targeted manner. In the future, particle size specifications in the context of the organosolv process should be expressed in terms of distribution densities rather than in terms of a smaller than specification., (© 2024 The Author(s). Macromolecular Bioscience published by Wiley‐VCH GmbH.)

The conversion of lignocellulosic biomass into value-added chemicals and biofuels has been attracting the attention of researchers in recent years. Lignin is an abundant, natural polymer and a major component of lignocellulose comprising an aromatic structure with ether linkages, methoxy-, and hydroxyl groups. Therefore, it has great potential as a sustainable source to produce basic chemical products. In this study, precious metal-loaded hydrotalcite (HTC) catalysts for the depolymerization of organosolv lignin (OL) were investigated concerning minimizing coke formation and maximizing the value-added lignin oil fraction and lignin tar fraction. The influences of the catalyst support, the platinum loading as well as the loading with a second metal (Cu or Ni) were examined. The resulting depolymerization fractions (lignin oil, lignin tar, aqueous fraction, and coke) were determined gravimetrically. To compare the molecular mass distribution of the lignin oil and lignin tar fractions as well as the purchased OL, gel permeation chromatography (GPC) was used. The lignin oil fractions were analyzed quantitatively and qualitatively by gas chromatography-mass spectroscopy (GC–MS). Regarding the most suitable catalyst system (5%Pt-1%Ni/HTC), a design of experiment (DoE) was prepared to further minimize coke formation and maximize the value-added fractions (lignin oil and lignin tar). This optimization led to 18 wt% lignin oil fraction, 72 wt% lignin tar fraction, and 0.4 wt% coke formation.

This work aims to offer a new acid type, methanesulfonic acid, to produce environmentally benign sulfonated carbon-based catalysts for esterification. The sulfonated catalysts were synthesized using two types of lignin sources, commercial lignin (CL) and lignin extracted from sugarcane bagasse (EL) through solvothermal carbonization and followed by sulfonation step. Overall, lignin sources and types of sulfonic acids were the factors affecting the catalyst performance. The results indicated that the high oxygenated functional groups on surface of chars prepared from EL gave the materials with better catalytic performance than prepared from CL. Moreover, the catalysts functionalized with methanesulfonic acid presented the higher catalytic activity than with sulfuric acid due to their higher surface area and better thermal stability. The highest methyl stearate yield (89.2%) from esterification of stearic acid with methanol were achieved at 240 °C with the reaction time of 10 min using the molar ratio of stearic acid to methanol of 1:9 and catalyst loading of 5 wt% in case of using EL char as a carbon source and methanesulfonic acid as a sulfonating agent. The catalyst could also be reused up to seven cycles with a yield higher than 80%. [ABSTRACT FROM AUTHOR]

Converting lignocellulosic materials to carbon quantum dots (CQDs) has garnered significant interest to transform biomass wastes into highly valuable products. We chose to use lignin as our feedstock because high-value products more readily utilize cellulose and hemicellulose. Lignin, arguably the most underutilized and complex biopolymer within any biomass, presents an appealing yet overlooked opportunity. While some may argue that lignin-based CQDs are no longer groundbreaking, this is because existing studies typically rely on commercially available lignin, ignoring biomass-derived sources. Therefore, in our pioneering research, we utilized organosolv lignin, prized for its structural purity and extracted from Moso bamboo waste, as the carbon source in a facile two-step technique to synthesize luminous CQDs. The process involved the addition of 2,4-diaminobenzenesulfonic acid, a mild-organic acid that acted as a source for both nitrogen (N) and sulphur (S). A 12-h hydrothermal treatment at 200 °C with 0.1 M of acid addition attained the best result. The resultant CQDs display strong green fluorescence, with the highest quantum yield of 17.7% seen in N and S co-doped CQDs. With their obvious and specific fluorescence quenching impact on Fe3+, CQDs demonstrate great potential as a fluorescent nanoprobe for metal ion detection. This CQD nanoprobe responds very sensitively to Fe3+ between 0 and 500 μM (R2 = 0.9803), with a detection limit of 0.15 μM. This research not only presents a unique alternative nanoprobe for the sensing field using renewable biomass lignin, but it also paves the way for the long-term, cost-effective, and scalable manufacturing of CQDs. [Display omitted] • Performed the synthesis of bio-based CQDs from bamboo-biomass lignin. • Doped with a mild organic acid additive, serving as N and S sources. • Unveiled potential as a potent green-fluorescent nanoprobe for Fe3+ detection. • Achieved 17.7% QY, responding to Fe3+ with a detection limit of 0.15 μM. • Paving way for a greener and scalable manufacturing of CQDs. [ABSTRACT FROM AUTHOR]

This research study evaluates the techno-economic and environmental performance of an olive leaves based biorefinery to produce antioxidants, bioethanol, and organosolv lignin. The biorefinery comprises processes such as organosolv extraction, organosolv pretreatment and simultaneous saccharification and fermentation, which were simulated in Aspen Plus v9.0. Experimental data were used to simulate the process, assuming a linear up-scaling. The techno-economic evaluation was carried out considering financial indicators such as net present value (NPV) and internal rate of return (IRR). The environmental assessment was done applying the life cycle assessment methodology. The results shows that 100 g olive leaves can produce 16.58 g antioxidant extract, 11.12 g organosolv lignin, and 2.85 g bioethanol. The proposed biorefinery was feasible at a processing scale of 30,000 t/y with a NPV of 47.9 million USD and an internal rate of return of 27.8%. The proposed biorefinery can be implemented in Jaén (Andalusia-Spain) based on the high amount of olive leaves produced in this region. Stillages are the most polluting waste stream of the process. The carbon footprint of the biorefinery was 1.13 kgCO 2 -eq/kg olive leaves. The application of the biorefinery concept revealed that olive leaves could be transformed into value-added products from a techno-economic and environmental perspective. • Techno-economic and environmental analysis of an olive-leave-based biorefinery. • Co-production of antioxidants,lignin, and bioethanol is economically attractive. • Chemical reagents and stillage treatment are main drivers of environmental footprints. [ABSTRACT FROM AUTHOR]

European aspen (Populus tremula (L.) (Salicaceae)) bark is a promising raw material in multi-step biorefinery schemes due to its wide availability and higher content of secondary metabolites in comparison to stem wood biomass. The main objective of this study was to investigate the major cell wall component-enriched fractions that were obtained from aspen bark residue after extractives isolation, primarily focusing on integration of separated lignin fractions and cellulose-enriched bark residue into complex valorization pathways. The "lignin first" biorefinery approach was applied using mild organosolv delignification. The varying solvent systems and process conditions for optimal delignification of residual aspen bark biomass were studied using a response surface methodology approach. The conditions for maximum process desirability at which the highest amount of lignin-enriched fraction was separated were as follows: 20-h treatment time at 117 °C, butanol/water 4:1 (v/v) solvent system with solid to liquid ratio of 1 to 10. At optimal separation conditions, lignin-enriched fraction exhibited a higher content of β–O–4 linkages vs. C–C linkages content in its structure as well as a high amount of hydroxyl groups, being attractive for its further valorization. At the same time, the content of glucose in products of cellulose-enriched residue hydrolysis was 52.1%, increased from 10.3% in untreated aspen bark. This indicates that this fraction is a promising raw material for obtaining cellulose and fermentable glucose. These results show that mild organosolv delignification of extracted tree bark can be proposed as a novel biorefinery approach for isolation of renewable value-added products with various application potentials. [ABSTRACT FROM AUTHOR]

Simple Summary: As global efforts to use eco-friendly and reusable materials increase, the use of lignin from waste biomass will continue to intensify. Lignin is an underutilized biowaste macromolecule that is gaining considerable interest in biomedical research. However, the source of lignin and the extraction process heavily influence its chemistry, which can influence a cell's reaction to lignin. Organosolv lignin is extracted via an eco-friendly process from leftover waste material. Few studies have tested the biocompatibility of organosolv lignins with human cells. We extensively characterized fractionated organosolv lignin and performed in vitro cytotoxicity safety screening on diverse primary human cell types commonly used in tissue engineering. This is the first study to show that, at a balanced concentration, fractionated low MW beechwood-derived organosolv lignin is non-cytotoxic to highly relevant human cell types used in tissue engineering including human bone marrow-derived mesenchymal stromal cells (MSCs), chondrocytes, osteoblasts, periodontal ligament fibroblasts, gingival fibroblasts and keratinocytes. Additionally, we show that organosolv lignin can be used to fabricate cell scaffolds and that addition of lignin increased the stiffness and viscosity of the scaffolds as well as cell attachment. This suggests that organosolv lignin may be used in the generation of tissue-like biomaterial-based constructs for tissue repair. There is limited data assessing the cytotoxic effects of organosolv lignin with cells commonly used in tissue engineering. Structural and physico-chemical characterization of fractionated organosolv lignin showed that a decrease of the molecular weight (MW) is accompanied by a less branched conformation of the phenolic biopolymer (higher S/G ratio) and an increased number of aliphatic hydroxyl functionalities. Enabling stronger polymer−solvent interactions, as proven by the Hansen solubility parameter analysis, low MW organosolv lignin (2543 g/mol) is considered to be compatible with common biomaterials. Using low MW lignin, high cell viability (70–100%) was achieved after 2 h, 24 h and 7 days using the following lignin concentrations: MSCs and osteoblasts (0.02 mg/mL), gingival fibroblasts and keratinocytes (0.02 to 0.04 mg/mL), periodontal ligament fibroblasts and chondrocytes (0.02 to 0.08 mg/mL). Cell viability was reduced at higher concentrations, indicating that high concentrations are cytotoxic. Higher cell viability was attained using 30/70 (w/v) NaOH vs. 40/60 (w/v) EtOH as the initial lignin solvent. Hydrogels containing low MW lignin (0.02 to 0.3 mg/mL) in agarose dose-dependently increased chondrocyte attachment (cell viability 84–100%) and hydrogel viscosity and stiffness to 3–11 kPa, similar to the pericellular matrix of chondrocytes. This suggests that low MW organosolv lignin may be used in many tissue engineering fields. [ABSTRACT FROM AUTHOR]

In this work, the catalytic liquefaction of eucalyptus organosolv lignin (EOL) over hydrogen type-zeolite socony mobile-five (HZSM-5) zeolite supported transition metals in an ethanol system was studied, and a cheap transition metal NiCr/HZSM-5 catalyst was prepared. Among them, nickel and chromium proved to have a good synergistic effect, which could remarkably enhance the acidity of the catalyst surface, and the catalytic effect was better than Ru-based precious metal catalysts and commercial Raney Ni catalysts. Meanwhile, the optimal reaction process of NiCr/HZSM-5 and Raney Ni catalyst for synergistic catalysis of EOL was explored. Under the optimal process conditions, the lignin liquefaction rate reached 95.9%, the monophenol yield was 8.64%, and the char content was only 2.08%. Furthermore, ¹H13C heteronuclear single quantum correlation nuclear magnetic resonance (¹H13C HSQC NMR) showed that the β-O-4, β-β, and β-5 linkages of lignin were effectively broken. Thus, a higher liquefaction rate of lignin was realized, which provided the possibility for further comprehensive utilization of lignin. [ABSTRACT FROM AUTHOR]

Developing fully biobased products with functionality in a green fashion is highly desirable to meet the increasing demand for environmental sustainability and mitigate "white pollution" by petroleum-based counterparts. Here, chitin from shrimp shells was propionylated to obtain chitin propionate (CP) with significantly improved solubility in organic solvents, organosolv lignin (OSL) was extracted from the forest harvest residuals. The fully biobased composite consisting of CP as a matrix and OSL as a UV-blocker were successfully prepared using acidic ethanol/water as a green processing solvent. The results indicated that the 5% OSL addition enabled the CP film to block approximately 98% UV light while allowing 71% visible light transmittance; tensile and thermal properties were also retained. Nearly 100% UV light was blocked with 20% OSL addition, but visible light transmittance was moderately sacrificed. This study provides an alternative solution to produce novel fully biobased films with high transparency yet excellent UV protection for potential packaging applications. Graphic abstract [Display omitted] [ABSTRACT FROM AUTHOR]

More wood for technical valorization is to be expected in Europe over the coming years, due to climate change and the bark beetle. To further independence from fossil‐fuel resources a novel approach to the base‐catalyzed depolymerization (BCD) of organosolv lignin into monomers and oligomers, while maximizing yields and minimizing coke formation, was scaled up in a theoretical wood‐based biorefinery with a yearly input of 40 000 t of wood chips. Other process steps were modeled from the literature. A novel work‐up approach was evaluated under laboratory conditions, implemented, and compared with a simulation‐based pervaporation technique. The life‐cycle assessment (LCA) showed that the biorefinery provided a significantly lower global warming potential (GWP) (excluding biogenic carbon) than its fossil counterparts. Moreover, the majority of impacts on the other midpoint categories was also smaller than for the fossil reference. However, after allocating the GWPs, it was evident that subsequent conversion of the C6 fraction to value‐added products is necessary for optimal results. The discounted cash flow analyses for the biorefinery setups (40 to 400 kt year–1) showed that they were not profitable with prices based on fossil references. However, when using higher prices/t from the literature, such as €1615 for monomers, €2000 for oligomers, and €510 for C6 sugars, a positive net present value could be reached at approximately 100 000–120 000 t processed annually. Hence, the conclusion was that a biorefinery utilizing wood not only brings environmental benefits and a reduction in the use of fossil resources but can also be financially beneficial. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd [ABSTRACT FROM AUTHOR]

Effects of alkaline (kraft and soda) and organosolv pulping were evaluated relative to the structural properties of lignin isolated from coconut husk (CH) biomass. The various types of functional groups within the isolated lignin samples were characterized and compared using a variety of complementary analyses including Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and high-performance liquid chromatography (HPLC). All isolated CH lignin samples contained a significant quantity of non-condensed guaiacyl-type (G) and syringyl-type (S) units but a lesser amount of p-hydroxyphenyl (H) units, as demonstrated and supported by previous research. The alkaline CH lignin produced lignin with higher molecular weight (Mw SL: 959 g mol-1 > Mw KL: 769 g mol-1 ) than the organosolv lignin (Mw OL: 606 g mol-1 ) sample, resulting in smaller fragments and a higher degree of solubility in water or other solvents. Because of significant differences in the physicochemical characteristics of the various lignin polymers, their properties and structure were improved with respect to alternative approaches in lignin-based applications. [ABSTRACT FROM AUTHOR]

The targeted application of lignin needs deeper understanding of its physicochemical property. Herein, three kinds of organosolv lignin samples were obtained from willow using three typical organosolv-water co-solvents, and their properties and pyrolysis behaviors were studied by various characterization methods. It was found that the used solvents exerted different effects on lignin samples: lignin extracted from ethyl acetate-water co-solvent possessed more functional groups containing oxygen, and lignin extracted from γ-butyrolactone-water co-solvent contained more large-molecule fragments; the degradation temperature with the maximum rate in thermogravimetric analysis were 352, 384, and 398 ℃ for lignin samples extracted by ethyl acetate/tetrahydrofuran/γ-butyrolactone-water co-solvent, respectively. The cleavage of Cα-Cβ linkage performed more acutely in pyrolysis of lignin extracted from γ-butyrolactone-water co-solvent, while the linkage of C1-Cα in lignin extracted by ethyl acetate/tetrahydrofuran-water co-solvent was more fragile. With regard to the mono-phenolic products, the pyrolysis of lignin extracted from ethyl acetate-water co-solvent yielded guaiacol and 4-methylguaiacol dominantly, and lignin extracted by tetrahydrofuran-water co-solvent produced more guaiacol, 4-ethylguaiacol, and 4-methylguaiacol while lignin extracted by γ-butyrolactone-water co-solvent yielded the maximum amount of 4-methylguaiacol. In addition, the pyrolysis of lignin samples extracted by γ-butyrolactone-water co-solvent yielded only H2, CH4 and CO as gaseous products while the other two yielded H2, CH4, CO and CO2.

Sugarcane bagasse was pretreated with lewis acid-mediated glycerol, results showed that 98.47% glucan recovery, 95.31% xylan removal and 49.69% delignification were achieved by pretreatment using 80 wt% aqueous glycerol combined with 1.0 wt% AlCl 3 at 150 °C for 1 h. Reutilization experiments of acidified glycerol showed that its pretreatment efficiency was relatively well maintained during four consecutive cycles. Enzymatic in situ saccharification of pretreated bagasse led to about 50% glucose yield at 16 wt% glycerol concentration. After pretreatment, the lignin distributed in pretreatment hydrolysate and pretreated solid residue (referred to as organosolv lignin (OL) and cellulolytic enzyme lignin (CEL), respectively) demonstrated contrasting effect on enzymatic hydrolysis with OL slightly increasing while CEL decreasing cellulose conversion, which could be explained by their differences in hydrophobicity and surface charge. Further analysis of the structure and molecular weights of two lignin samples indicated their great potential for valorization into value-added products. • Lignin and xylan were significantly removed with nearly complete glucan recovery. • Recycled acidified glycerol maintained good pretreatment efficacy. • High-concentration glycerol in one-pot process strongly inhibit cellulase. • Organosov lignin slightly increased cellulose hydrolysis. • Cellulolytic enzyme lignin decreased cellulose hydrolysis. [ABSTRACT FROM AUTHOR]

Corrosion and wear remain significant challenges for materials, causing substantial economic losses and safety risks. Anti-corrosion and anti-wear coatings provide an effective solution. However, traditional coatings are often fossil-based and contain heavy metals, posing environmental concerns. The drive for eco-friendly coatings has led to the exploration of green materials. This study combined lignin, an abundant organic material, and polydimethylsiloxane (PDMS), a known hydrophobic material, to address the challenges. Organosolv lignin was functionalised with (3-Aminopropyl)triethoxysilane (APTES), then chemically grafted on PDMS for the final coating synthesis. The optimised coating achieved through an eco-friendly process, exhibiting enhanced hydrophobicity and barrier properties, showing excellent long-term corrosion resistance in NaCl solution. The optimal coating formulation contained 15 wt% lignin and 40 wt% PDMS, demonstrating a high corrosion resistance (measured impedance of 1010 Ω·cm2), which remains effective even after 3 weeks of immersion in 1 M NaCl solution. This coating also showed good wear resistance, with a low friction coefficient evident from nano scratch tests. [Display omitted] • Successfully integrates 15 wt.% silane-modified organosolv lignin with 40 wt.% polydimethylsiloxane. • The eco-friendly coating shows long-term corrosion resistance, with an impedance of 1010 Ω·cm2. • The coating remains effective even after being exposed to 1 M NaCl solution for 3 weeks. • The coating exhibits good wear resistance and a low friction coefficient of 0.15. • This work represents a significant step towards environmentally friendly coatings. [ABSTRACT FROM AUTHOR]

Lignin has been overlooked and used as a waste for long due to its complex and partially hydrophobic structure. Many efforts have been carried out to overcome these deficiencies and apply it as a high-value product, which are insufficient to reach the full potential of lignin in various advanced applications, since they require with procedures for the obtaining of more specific and fine-tuned chemical structures. This work focuses on the obtaining of differently structured hydrophilic lignins derived both from Kraft and organosolv isolation processes. The chemical structures of the different lignin types were studied, and the effect of the structural differences in the modification processes and their subsequent properties analyzed, valorizing their potential application for diverse purposes. The carboxymethylation and sulfomethylation reactions were carried out with the aim of enhancing the polarity of the lignin samples, while the methylation reaction aimed to obtain lignins with higher stability. The physicochemical analyses of the samples, carried out by FTIR, GPC, 31P NMR, 13C NMR, and HSQC NMR, verified the effectiveness of the chemical reactions and conditions selected, obtaining lignins with lower hydroxyl content, due to their substitution and insertion of carboxymetyl, sulfomethyl and methyl groups, therefore obtaining more condensed, aromatic and oxygenated aromatic carbon structures. While the methylation reaction was the most efficient in substituting the OH groups, due to its non-selectivity, OL showed higher modification yields than KL. In terms of the thermal and morphological properties, analyzed by DLS and TGA respectively, it was observed that the modified samples showed lower Z potential values, along with higher conductivity, being the sulfomethylated organosolv lignin the one showing the best results, which was also the one with the smallest particle size and polydispersity index. Finally, all the modified samples showed higher T 50% values, suggesting a better stability towards degradation. • Kraft and organosolv lignin were modified by different chemical reactions. • Carboxymethylation, sulfomethylation, and methylation reactions were effective on reacting with the lignin hydroxyl groups. • Higher thermal stability and water dispersion were obtained by the incorporation of the functional groups into lignin. [ABSTRACT FROM AUTHOR]

The attention to pursuing biodegradable fillers as reinforcement in three‐dimensional (3D) printing filament and enhancing interlayer adhesion has led to the exploitation of agricultural biomass. In this study, organosolv lignin fillers can act as the aforementioned twofold purposes in preparing acrylonitrile butadiene styrene (ABS) filament for fused deposition modeling (FDM). In this study, the lignin polymer composites were homogenized with graphene nanoplatelets (GnPs) as a reinforcer. Essentially, ABS 3D printing at 90o with the reinforcement fillers shows a significant increment in the mechanical properties owing to better interlayer adhesion. The printed product promotes a substantial improvement on the tensile stress up to 29.1% compared with neat polymers. Furthermore, 3D printing using lignin/GnP composite filaments shows the feasibility of biofillers to be used as filaments for FDM 3D printing of complex geometries even though the surface finish has been affected. [ABSTRACT FROM AUTHOR]

A fractionation scheme for lignocellulosic biomass where major constituent biopolymers are recovered in applicable forms is essential for integrated biorefinery. In this study, a sequential two-step fractionation of sugarcane bagasse using liquid hot water followed an organic acid-catalyzed aqueous glycerol-based organosolv process was developed. Under optimal conditions, 66.1% of the hemicellulose was recovered as saccharides by the acid-catalyzed hydrothermal step. Formic acid was superior to H2SO4 and HNO3 as a catalyst for the subsequent organosolv step using aqueous glycerol in terms of delignification efficiency and selectivity, resulting in a maximum of 78.3% lignin recovery after acetone extraction with > 90% purity and better conservation of aromatic subunit structure according to 2D-NMR. The majority of cellulose (86.4%) was retained as a solid with high purity (74.8%) and enzymatic digestibility, resulting in 78.2% glucose recovery. The formic acid-aqueous glycerol-spent liquor could be recycled for at least four consecutive batches with no significant decrease in product yield or selectivity. The work represents an efficient sequential process for fractionation of lignocellulose-derived components which allowed solvent recycling and recovery of high-purity lignin with conserved subunit structure. The separated product streams are suitable for valorization in biorefinery. Graphical abstract [ABSTRACT FROM AUTHOR]

European aspen (Populus tremula (L.) (Salicaceae)) bark is a promising raw material in multi-step biorefinery schemes due to its wide availability and higher content of secondary metabolites in comparison to stem wood biomass. The main objective of this study was to investigate the major cell wall component-enriched fractions that were obtained from aspen bark residue after extractives isolation, primarily focusing on integration of separated lignin fractions and cellulose-enriched bark residue into complex valorization pathways. The “lignin first” biorefinery approach was applied using mild organosolv delignification. The varying solvent systems and process conditions for optimal delignification of residual aspen bark biomass were studied using a response surface methodology approach. The conditions for maximum process desirability at which the highest amount of lignin-enriched fraction was separated were as follows: 20-h treatment time at 117 °C, butanol/water 4:1 (v/v) solvent system with solid to liquid ratio of 1 to 10. At optimal separation conditions, lignin-enriched fraction exhibited a higher content of β–O–4 linkages vs. C–C linkages content in its structure as well as a high amount of hydroxyl groups, being attractive for its further valorization. At the same time, the content of glucose in products of cellulose-enriched residue hydrolysis was 52.1%, increased from 10.3% in untreated aspen bark. This indicates that this fraction is a promising raw material for obtaining cellulose and fermentable glucose. These results show that mild organosolv delignification of extracted tree bark can be proposed as a novel biorefinery approach for isolation of renewable value-added products with various application potentials.

There is limited data assessing the cytotoxic effects of organosolv lignin with cells commonly used in tissue engineering. Structural and physico-chemical characterization of fractionated organosolv lignin showed that a decrease of the molecular weight (MW) is accompanied by a less branched conformation of the phenolic biopolymer (higher S/G ratio) and an increased number of aliphatic hydroxyl functionalities. Enabling stronger polymer−solvent interactions, as proven by the Hansen solubility parameter analysis, low MW organosolv lignin (2543 g/mol) is considered to be compatible with common biomaterials. Using low MW lignin, high cell viability (70–100%) was achieved after 2 h, 24 h and 7 days using the following lignin concentrations: MSCs and osteoblasts (0.02 mg/mL), gingival fibroblasts and keratinocytes (0.02 to 0.04 mg/mL), periodontal ligament fibroblasts and chondrocytes (0.02 to 0.08 mg/mL). Cell viability was reduced at higher concentrations, indicating that high concentrations are cytotoxic. Higher cell viability was attained using 30/70 (w/v) NaOH vs. 40/60 (w/v) EtOH as the initial lignin solvent. Hydrogels containing low MW lignin (0.02 to 0.3 mg/mL) in agarose dose-dependently increased chondrocyte attachment (cell viability 84–100%) and hydrogel viscosity and stiffness to 3–11 kPa, similar to the pericellular matrix of chondrocytes. This suggests that low MW organosolv lignin may be used in many tissue engineering fields.

The heterogeneity and complexity of lignin necessitate a deep understanding to select the most appropriate lignin valorization and convert it into value-added products. The objective of this research is to investigate the features of organosolv and Kraft lignins, in order to understand the effects of the sources and the isolation treatment, through the comparison of physicochemical and thermal properties. Various techniques have been employed such us Fourier transform infrared spectroscopy (FTIR), carbon solid state nuclear magnetic resonance 13CNMR, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. It was found that lignin produced from the hardwood using the Kraft process provided the greatest yield compared to other combinations. Softwood pretreatments achieve almost higher sugar yield than hardwood treatments. The infrared spectroscopy analysis confirms the existence of different monolignols. Organosolv lignins showed a predominance of guaiacyl and syringyl units. To provide additional information, the principle components analysis, as a powerful chemometric method, has also been applied to evaluate the FTIR data. NMR spectroscopy of lignins demonstrated the presence of essential functional chemical groups. It is also revealed that the nature of the treatment and the source of lignin samples affect the thermal properties. Overall, lignin isolated from Aleppo pine using Kraft process presented better thermal stability than that of organosolv lignin. [ABSTRACT FROM AUTHOR]