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A crucial step in the chemical delignification of wood is the transport of lignin fragments into free liquor; this step is believed to be the rate-limiting step. This study has investigated the diffusion of kraft lignin molecules through model cellulose membranes of various pore sizes (1–200 nm) by diffusion cells, where the lignin molecules diffuse from donor to acceptor cells through a membrane, where diffusion rate increases by pore size. UV–vis spectra of the donor solutions showed greater absorbance at higher wavelengths (~450 nm), which was probably induced by scattering due to presence of large molecules/clusters, while acceptor samples passed through small pore membranes did not. The UV–vis spectra of acceptor solutions show a characteristic peak at around 350 nm, which corresponds to ionized conjugated molecules: indicating that a chemical fractionation has occurred. Size exclusion chromatography (SEC) showed a difference in the molecular weight (Mw) distribution between lignin from the donor and acceptor chambers. The results show that small pore sizes enable the diffusion of small individual molecules and hinder the transport of large lignin molecules or possible lignin clusters. This study provides more detail in understanding the mass transfer events of pulping processes. [ABSTRACT FROM AUTHOR]

This study addresses changes in aesthetical features of bio-based polyurethane (PU) foams filled with four forest-based particles (namely wood flour, wood bark, kraft lignin, and paper sludge), which were decayed by two wood-rot fungi. White-rot and brown-rot fungi were inoculated on these foams and further characterization results were obtained using colourimetric parameters measured according to the CIELab method. The fungi penetrated into both intra and intercellular spaces into the PU foams, although it neither changed the foam weight nor chemically interacted with the polymer cell wall. These fungi changed overall the appearance of the foams, which indicates that a protective strategy against these microorganisms may be of interest, especially for foam parts used in contact with wood products. The neat PU presented smaller colour stability if compared to the filled foams. Among the fillers, powdered kraft lignin stood out and can be indicated to produce valuable darkened PU parts with stable colour patterns. [ABSTRACT FROM AUTHOR]

Polyurea microcapsules containing oxyfluorfen herbicide were synthesized by interfacial polymerization reaction between toluene diisocyanate and ethylene diamine at various core to shell ratios using green solvent N-N-dimethyldecanamide as carrier medium and using biodegradable PVA203S and Kraft lignin grade (varying molecular weight) as the emulsifying agent. The study was done to understand the effect of stirring rate on preparing microcapsules and find out how the process conditions changed the attributes of microcapsules such as particle size distribution, encapsulation efficiency and release kinetics. The formation of capsules was confirmed by FT-IR, SEM and TGA. The study indicated that the encapsulation efficiency decreased with increasing core to shell ratio. The change in release kinetics was based on the stirring rate and was dependent on the pH of release medium. Particle size distribution was influenced by the agitation speed during formation of emulsion. Kraft lignins of varying molecular weight were used to synthesize the polyurea capsules. It was found that capsules with high molecular weight lignin showed slow and sustained release. Synthesized polyurea capsules was subjected to safety study on paddy crop and compared with commercially available oxyfluorfen and was found to be safe for use on paddy crop.

Lignin is one of the primary residues obtained after the processing of lignocellulosic biomass. However, most residual lignin is burnt directly to get rid of it, albeit one of the few biorenewable waste resources that can yield aromatics. Therefore, the present study investigates reductive depolymerization of Kraft lignin into aromatics in the presence of Pt/HZSM-23 catalyst. In this regard, the lignin conversion experiments were performed under mild reaction conditions at a temperature range of 100 °C to 200 °C for 1 h to 12 h in a high-pressure batch reactor. Besides, a comparative study was done on the effect of the supply of external hydrogen and in-situ hydrogenation. Eventually, 87.3% lignin conversion was measured yielding 65.1% bio-oil, primarily aromatics at optimized experimental conditions. It was observed that the mesopores in the Pt/HZSM-23 catalyst facilitate the transfer of larger molecules derived from the Kraft lignin, thus causing an overall improvement in the catalytic activity. A mechanistic study based on experimental conditions and products detected using GC-MS revealed that the in-situ hydrogen transfer route is more favorable for lignin depolymerization than externally supplied hydrogen.

This research focuses on key priorities in the field of sustainable plastic composites that will lead to a reduction in CO2 pollution and support the EU's goal of becoming carbon neutral by 2050. The main challenge is to develop high-performance polyphenol-reinforced thermoplastic composites, where the use of natural fillers replaces the usual chemical additives with non-toxic ones, not only to improve the final performance but also to increase the desired multifunctionalities (structural, antioxidant, and antibacterial). Therefore, poly (lactic acid) (PLA) composites based on Kraft lignin (KL) and tannin (TANN) were investigated. Two series of PLA composites, PLA-KL and PLA-TANN, which contained natural fillers (0.5%, 1.0%, and 2.5% (w/w)) were prepared by hot melt extrusion. The effects of KL and TANN on the PLA matrices were investigated, especially the surface physicochemical properties, mechanical properties, and antioxidant/antimicrobial activity. The surface physicochemical properties were evaluated by measuring the contact angle (CA), roughness, zeta potential, and nanoindentation. The results of the water contact angle showed that neither KL nor TANN caused a significant change in the wettability, but only a slight increase in the hydrophilicity of the PLA composites. The filler loading, the size of the particles with their available functional groups on the surfaces of the PLA composites, and the interaction between the filler and the PLA polymer depend on the roughness and zeta potential behavior of the PLA-KL and PLA-TANN composites and ultimately improve the surface mechanical properties. The antioxidant properties of the PLA-KL and PLA-TANN composites were determined using the DPPH (2,2′-diphenyl-1-picrylhydrazyl) test. The results show an efficient antioxidant behavior of all PLA-KL and PLA-TANN composites, which increases with the filler content. Finally, the KL- and PLA-based TANN have shown resistance to the Gram-negative bacteria, E. coli, but without a correlation trend between polyphenol filler content and structure. [ABSTRACT FROM AUTHOR]

Softwood kraft lignin is a major bioresource relevant to the production of sustainable bio-based products. Continued challenges to lignin valorization, however, include poor solubility in organic solvents and in aqueous solutions at neutral pH. Herein, an alkaline tolerant laccase was used to graft acrylate functionalities onto softwood kraft lignin, which is expected to enhance the reactivity of lignin with isocyanate when producing bio-based polyurethanes. Proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and high-performance liquid chromatography were used to confirm successful grafting of the acrylate monomer onto lignin and verify the importance of including tert-butyl hydroperoxide as an initiator in the grafting reaction. Laccase-mediated grafting of softwood kraft lignin under alkaline conditions produced lignin products with approximately 30% higher hydroxyl value and higher reactivity toward isocyanate. The reported enzymatic and aqueous process presents an opportunity for the sustainable valorization of softwood kraft lignin. Key points: • Softwood kraft lignin displayed high phenolic hydroxyl content, polydispersity index and average molecular weight • Grafting hydroxyethyl acrylate (HEA) monomer onto kraft lignin by laccase was successful at 60 °C and alkaline conditions • Lignin-HEA grafted copolymer showed an increase in total OH value and an increase in average molecular weight [ABSTRACT FROM AUTHOR]

In the present study, oil-in-water (O/W) sunscreen emulsions were prepared containing different portions of lignin (LGN), multiwall carbon nanotubes (MWCNTs) and graphene oxide (GO) nanoadditives. The stability in terms of pH and viscosity of emulsions was thoroughly studied for up to 90 days, exhibiting high stability for all produced O/W emulsions. The antioxidant activity of emulsions was also analyzed, presenting excellent antioxidant properties for the emulsion that contains LGN due to its phenolic compounds. Moreover, the emulsions were evaluated for their ultraviolet (UV) radiation protection ability in terms of sun protection factor (SPF) and UV stability. SPF values varied between 6.48 and 21.24 while the emulsion containing 2% w/v MWCNTs showed the highest SPF index and all samples demonstrated great UV stability. This work hopefully aims to contributing to the research of more organic additives for cosmetic application with various purposes. [ABSTRACT FROM AUTHOR]

The waterborne polyurethane (WPU) exposed to outdoor environment for a long time are more likely to reduce their mechanical performance and service life. This work describes a simple and effective method to obtain the homogeneous lignin/TiO 2 nanocomposite as the anti-UV additive to improve the applicability of WPU. The SKLs/TiO 2 were prepared by the gradient sulfonation kraft lignin (SKLs) and tetrabutyl titanate. The particle morphology and hybrid structure of SKLs/TiO 2 are characterized by FT-IR, zeta potential analysis, XPS, TG and SEM. Interestingly, it was found that the change of π-π interactions and electrostatic repulsion between SKL molecules effected the forming of SKLs/TiO 2 nanocomposite. The lignin content and morphology of SKLs/TiO 2 nanocomposite could be controlled by regulating the sulfonate group content on lignin molecular. Furthermore, the SKLs/TiO 2 nanocomposites was successfully applied on water polyurethane film as the additive, when SKLs/TiO 2 content increased from 0 wt% to 5.0 wt%, the tensile strength increased 43%, the elongation at break increased from 240.0% to 352.0% and the UV transmittance reduced from 87% to 1.7% below 400 nm, which greatly improved the UV resistance and mechanical properties. The results of this study are of significant and practical importance to the high-value-added utilization of lignin. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of Kraft Lignin (KL) experiments were carried out at different temperatures (350–500 °C) over base MgO, acidic ZSM-5 and mixture of MgO-ZSM-5 catalysts under different environments (N 2 and CO 2). Non-catalytic reaction produced maximum bio-oil (35.3 wt%) under CO 2 at 450 °C. Upgrading of pyrolysis vapor under different environment with catalysts produced lower bio-oil as it is enhanced cracking and coke formation. Higher intensity peak at 1695–1720 cm-1 was found in up-gradation pyrolysis KL vapor under CO 2 , which showed that the higher aldehyde/acidic or ketone functionality in bio-oil. The content of monocyclic aromatic hydrocarbons increased whereas phenolic compound decreased with using the catalysts under N 2 while acidic functionality increased under CO 2 environment. Our results suggest that mixture of catalysts showed synergistic effects which increased the bio-oil quality. Overall, mixture of MgO-ZSM-5 showed the highest yield of aromatic hydrocarbons (ca. 49.2%) under N 2. Significant amount oxygen content reduced with the mixture of catalyst (MgO-ZSM-5, 1:1 ratio) under N 2 with the increasing of aromatic hydrocarbon. Higher heating value bio-oil was obtained with catalytic up-gradation. • Catalytic pyrolysis of Kraft Lignin (KL) was investigated under N 2 and CO 2. • Maximum bio-oil (35.3 wt%) was obtained without catalyst under N 2 at 450 °C. • Higher % of aromatic hydrocarbon compounds was obtained with catalyst mixture. • Catalytic bio-oil showed the higher heating value (HHV) 36.8 MJ/kg. [ABSTRACT FROM AUTHOR]

Lignin, a component of lignocellulosic biomass, is abundant and is produced extensively as a waste product of the Kraft pulping process, lignin obtained from this process is called Kraft lignin (KL). Lignin’s three-dimensional structure composed of aromatic alcohols (monolignols) makes it a potential source of renewable aromatic chemicals or bio-oil, if depolymerized. Among all the depolymerization methods for KL, solvolysis is the most popular, showing consistently high bio-oil yields. Despite the large number of studies that have been carried out, an economically feasible industrial process has not been found and comparison among the various studies is difficult, as very different studies in terms of reaction media and catalysts report seemingly satisfactory results. In this review, we compare and analyze KL solvolysis studies published, identify trends in bio-oil composition and give a comprehensive explanation about the mechanisms involved in the processes. Additional commentary is offered about the availability and future potential of KL as a renewable feedstock for aromatic chemicals, as well as logistical and technical aspects.

Lignosulfonate features sulfonate groups, which makes it soluble in water and hence, suitable for a wide range of applications. However, its characterization is challenging because of its limited solubility in organic solvents. Thus, this study investigated the chemical and thermal characteristics of ion-exchanged sodium lignosulfonate (Na-LS) and compared it with those of industrial kraft lignin derived from softwood and hardwood. The results demonstrated that the ion exchange successfully converted Na-LS to lignosulfonic acid (H-LS), as proven by the Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analysis. H-LS has a greater apparent molecular weight than those of Na-LS and softwood and hardwood kraft lignin (SKL and HKL). According to 31P nuclear magnetic resonance (NMR) analysis, H-LS has less phenolic OH than SKL and HKL, indicating that it has more polymeric chains. Furthermore, H-LS has substantially more native side chains, such as β-O-4 units, than SKL and HKL. Thermal analysis revealed that H-LS has a greater glass temperature (Tg) than SKL and HKL, although Na-LS has a lower Tg than SKL and HKL. In addition, H-LS degraded faster than Na-LS did because the acid condition accelerated degradation reaction.

Identification of the biochemical metabolic pathway for lignin decomposition and the responsible degradative enzymes is needed for the effective biotechnological valorization of lignin to renewable chemical products. In this study, we investigated the decomposition of kraft lignin by the soil bacterium Pseudomonas kribbensis CHA-19, a strain that can utilize kraft lignin and its main degradation metabolite, vanillic acid, as growth substrates. Gel permeation chromatography revealed that CHA-19 decomposed polymeric lignin and degraded dehydrodivanillin (a representative lignin model compound); however, the degradative enzyme(s) and mechanism were not identified. Quantitative polymerase chain reaction with mRNAs from CHA-19 cells induced in the presence of lignin showed that the putative genes coding for two laccase-like multicopper oxidases (LMCOs) and three dye-decolorizing peroxidases (DyPs) were upregulated by 2.0- to 7.9-fold compared with glucose-induced cells, which indicates possible cooperation with multiple enzymes for lignin decomposition. Computational homology analysis of the protein sequences of LMCOs and DyPs also predicted their roles in lignin decomposition. Based on the above data, CHA-19 appears to initiate oxidative lignin decomposition using multifunctional LMCOs and DyPs, producing smaller metabolites such as vanillic acid, which is further degraded via ortho - and meta -ring cleavage pathways. This study not only helps to better understand the role of bacteria in lignin decomposition and thus in terrestrial ecosystems, but also expands the biocatalytic toolbox with new bacterial cells and their degradative enzymes for lignin valorization.

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.

Laccase-mediator-oxidized lignin offers replacement for conventional chemical binders to produce fiberboards. Compared to the previously reported laccase–mediator system (LMS), a lignin-laccase-mediator-system (LLMS) has an advantage in that it requires much shorter fiber-enzyme incubation time due to significantly increased redox reactions. However, the cost of regularly applying laccase on an industrial scale is currently too high. We have employed CcLcc5 from cultures of the basidiomycete Coprinopsis cinerea as a novel basi-laccase (a CAZy subfamily AA1_1 laccase) in medium-density fiberboard (MDF) production, in comparison to the commercial formulation Novozym 51003 with recombinantly produced asco-laccase MtL (a CAZy subfamily AA1_3 laccase-like multicopper oxidase from the ascomycete Myceliophthora thermophila). With the best-performing natural mediator 2,6-dimethoxyphenol (DMP), unpurified CcLcc5 was almost as good as formulated Novozym 51003 in increasing the molecular weight (MW) of the technical lignins tested, the hydrophilic high-MW Ca-lignosulfonate and the hydrophobic low-MW kraft lignin (Indulin AT). Oxygen consumption rates of the two distantly related, poorly conserved enzymes (31% sequence identity) with different mediators and lignosulfonate were also comparable, but Indulin AT significantly reduced the oxidative activity of Novozym 51003 unlike CcLcc5, regardless of the mediator used, either DMP or guaiacol. Oxygen uptake by both laccases was much faster with both technical lignins with DMP than with guaiacol. In case of lignosulfonate and DMP, 20–30 min of incubation was sufficient for full oxygen consumption, which fits in well in time with the usual binder application steps in industrial MDF production processes. LLMS-bonded MDF was thus produced on a pilot-plant scale with either crude CcLcc5 or Novozym 51003 at reduced enzyme levels of 5 kU/kg absolutely dry wood fiber with lignosulfonate and mediator DMP. Boards produced with CcLcc5 were comparably good as those made with Novozym 51003. Boards reached nearly standard specifications in internal bond strength (IB) and modulus of rupture (MOR), while thickness swelling (TS) was less good based on the hydrophilic character of lignosulfonate. LLMS-bonded MDF with Indulin AT and DMP performed better in TS but showed reduced IB and MOR values.

Trameteshirsuta is a wood rotting fungus that possesses a vast array of lignin degrading enzymes, including7 laccases, 7 ligninolyticmanganese peroxidases, 9 lignin peroxidases and 2 versatile peroxidases. In this study, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS)was used to examine kraft lignin modification by the enzymatic system of this fungus. The observed pattern of lignin modification suggested that before the 6-hday of cultivation, the fungal enzymatic system tended to degrade more oxidized moleculesand, hence, less recalcitrant molecules, with the production of hard-to-modify reduced molecular species. At some point after the 6thday of cultivation, the fungus started to degrade less oxidized, more recalcitrant, compounds, converting them into the more oxidized forms. The altered pattern of lignin modification enabled changes in the fungal enzymatic system. These changes were further attributed to the appearance of the particular ligninolyticmanganese peroxides enzyme(MnP7), which was added by the fungus to the mixture of enzymes that had already been secreted (VP2 and MnP5). [ABSTRACT FROM AUTHOR]

Kraft lignin depolymerisation using hydrothermal liquefaction suffers from the formation of char, resulting in a decreased product yield as well as causing operational problems. While this may be mitigated by the addition of capping agents such as phenol and isopropanol, other reaction parameters, for example reaction time and temperature, are also important for the product yields. In this work, the effect of short reaction times on the hydrothermal liquefaction of kraft lignin in an alkaline water and isopropanol mixture was investigated at 1–12 min and 290 °C. The results show that there were swift initial reactions: the major ether bonds in the lignin were broken within the first minute of reaction, and the molecular weight of all product fractions was halved at the very least. Longer reaction times, however, do not cause as pronounced structural changes as the initial reaction, indicating that a recalcitrant carbon-carbon skeleton remained in the products. Nevertheless, the yields of both char and monomers increased slowly with increasing reaction time. The swift initial depolymerising reactions were therefore followed by slower repolymerisation as well as a slow formation of monomers and dimers, which calls for careful tuning of the reaction time. [ABSTRACT FROM AUTHOR]

In the current study, the effect on the adsorption of dyes (Basic red 2, Basic blue 3 and Ethyl orange) having almost similar molecular weight but belonging to different classes and functional groups on air activated carbon prepared from demineralised kraft lignin (DKLAAC) was investigated. The experimental and theoretical adsorption values for the dyes on DKLAAC were found to be 0.599, 0.550 and 0.395 mmol g-1 and 0.569, 0.520 and 0.387 mmol g-1 for Basic red 2, Basic blue 3 and Ethyl orange, respectively. Basic red 2 showed maximum adsorption (0.599 mmol g-1) on DKLAAC owing to more hydrophobicity and resonance in its structure. Contrarily, Ethyl orange showed minimum adsorption due to the hydrophilicity and less number of benzene rings. The presence of acid/basic site concentration of DKLAAC also affects the adsorption process. The obtained experimental data fitted best to the pseudo-second-order kinetic model. Thermodynamic parameters analysed confirms the feasibility, spontaneity and endothermic nature of the adsorption process. [ABSTRACT FROM AUTHOR]

Viscoelastic polyurethane (VE-PU), also known as memory foams are petroleum-based materials widely used in industry due to their specific properties, such as, comfort and low resilience. In this study, VE-PU foams were produced using different contents of Kraft lignin (KL) and palm kernel oil (PKO) additives, as partial substitutes of petroleum-based polyols. The study intends to replace methoxy-poly(ethylene glycol) (mPEG) with KL and PKO in the VE-PU formulation and to investigate the consequent effects on the foam growth profile, foaming reactivity and final properties of VE-PU foams (e.g., cell morphology, indentation strength, resilience, recovery time, deformation and sensory effect). The results indicate that it is possible to produce VE-PU foams by adding KL and PKO as additive to replace petroleum-based polyols. The addition of PKO and KL dispersed in petroleum-based polyol from 0 to 15wt%, had a significant effect on the growth profile, foaming reactivity and consequently on the foam morphology. The appearance of the VE-PU foams produced with PKO was similar to the control VE-PU foam sample. The foams with larger cells, induced densification and changes in the indentation strength, resilience and compression set test. Thermal properties of VE-PU foams showed a direct relationship to the content of KL used. The VE-PU foam with different PKO contents did not necessarily result in obtaining a foam with tactile sensory attributes. Mechanical properties of VE-foams can be adjusted by making changes to the standard formulation. In addition, these results point to a new approach for the application of VE-PU foams for packaging applications, as well as in the mattress industry. [ABSTRACT FROM AUTHOR]

The production of lignin nanoparticles (LNPs) has emerged as a way to overcome the highly variable and complex molecular structure of lignin. It can offer morphological control of the lignin polymer, allowing the formation of stable LNP dispersions in aqueous media, while increasing the potential of lignin for high‐value applications. However, the polydispersity and morphology of LNPs varies depending on the lignin grade and preparation method, and a systematic comparison using different technical lignins is lacking. In this study, it was attempted to find a green fabrication method with a distinct solvent fractionation of lignin to prepare LNPs using three different technical lignins as starting polymers: BLN birch lignin (hardwood, BB), alkali Protobind 1000 (grass, PB), and kraft LignoBoost (softwood, LB). For that, three anti‐solvent precipitation approaches to prepare LNPs were systematically compared: 70 % aqueous ethanol, acetone/water (3 : 1) and NaOH as the lignin solvent, and water/aqueous HCl as the anti‐solvent. Among all these methods, the acetone/water (3 : 1) approach allowed production of homogeneous and monodisperse LNPs with a negative surface charge and also spherical and smooth surfaces. Overall, the results revealed that the acetone/water (3 : 1) method was the most effective approach tested to obtain homogenous, small, and spherical LNPs from the three technical lignins. These LNPs exhibited an improved stability at different ionic strengths and a wider pH range compared to the other preparation methods, which can greatly increase their application in many fields, such as pharmaceutical and food sciences. [ABSTRACT FROM AUTHOR]

The objective of this work was to optimize the culture conditions for laccase production in the presence of Kraft lignin by Fusarium oxysporum JUMAD-053, and to evaluate the biodegradation products of lignin. The fungal isolate that presented highest laccase activity had its production optimized by a statistical factorial design 3³ in 15 experimental runs. F. oxysporum presented the highest constitutive laccase titer (5.37 U/mL). Statistical factorial design demonstrated a maximum laccase titer of 9.8 U/mL when assayed against ABTS under the conditions optimized: 1.125% (w/v) yeast extract, 0.5% (w/v) Kraft lignin and 10 days of cultivation. The maximum laccase titer when assayed on DMP was 8.4 U/mL, following the conditions optimized: 1.125% yeast extract, 0.25% Kraft lignin and 7 days of cultivation. The analysis of cultures led to identification of metabolites; two being aromatic: 2,6-dimethoxy benzoic acid and sesamin; also, fumonisin and long-chain fatty acids. As a result of the study, the maximum laccase activities of 9.8 and 8.4 U/mL measured from ABTS and DMP substrates, respectively. The search shows new sources of fungal laccase for obtaining new metabolites of biodegradation from Kraft lignin in culture medium. [ABSTRACT FROM AUTHOR]

The degradation of lignin cannot only reduce the impact of lignin pollutants on the environment, but it can also help to realize the efficient utilization of biomass resources. Obtaining the efficient lignin-degrading strain is necessary for the application of lignin biological degradation treatment. In this study, a novel lignin-degrading strain M01-L2 was isolated from a forest park in eastern China. The sequencing results showed that the M01-L2 strain was Burkholderia sp. H801. The kraft lignin degradation experiments showed that the lignin degradation efficiency of M01-L2 reached 49.8 % on the sixth day with the initial lignin concentration of 1 g L-1. This degradation process was carried out in the medium with lignin as the only carbon source. The lignin degradation process by M01-L2 strain mainly depended on the action of Lac and MnP enzymes. The MnP activity was maintained at a high level and increased significantly in the first four days, and the maximum value was 1544.4 U L-1. Lac enzyme activity increased significantly from the third day to the sixth day, reaching 757.9 U L-1 on the sixth day. This study can provide a new method for bacterial degradation of lignin. [ABSTRACT FROM AUTHOR]

In this work, different contents (0.25, 0.50, 0.75, and 1 phr) of dicumyl peroxide (DCP) are incorporated into the bio‐based high‐density polyethylene (bioPE)/kraft lignin (KL) blends with a composition of 80 and 20 wt%, respectively with the aim of improving overall performance. The samples are obtained by reactive extrusion and injection‐molding process, and then their overall performance is assessed by tensile tests, thermal analysis, optical and surface appearance, and wettability studies. The obtained mechanical properties confirm the successful interaction between bioPE and KL due to the addition of organic peroxide, which plays a key role in compatibilization. In particular, bioPE/KL blends with 1 phr of DCP achieve an increase in elongation at break of about 300% together with a noticeable increase in the impact strength of about 29% higher than the uncompatibilized bioPE/KL blend, while the tensile modulus decreases 42%. In addition, images obtained by field emission scanning electron microscopy show that the presence of DCP in the blends enhances better dispersion of KL into the bioPE matrix. The wettability analysis indicates that KL and DCP affect the hydrophobicity of the neat bioPE. Therefore, the resultant blends can be considered as potential sustainable polymers with balanced properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • A system containing Co-ZIF reinforced kraft lignin biochar catalyst was designed. • Co@NPC-KLB-A showed perfect catalytic activities for vanillin hydrodeoxygenation. • H-donner solvent was used for vanillin hydrodeoxygenation instead of external H 2. • Theoretical calculations further confirmed the active sites of the catalysts. • Co@NPC-KLB-A catalyst showed excellent stability after five recycling runs. Large amount of lignin was produced annually as a byproduct in papermaking and pulping processes, the challenges in disposal methods had posed serious obstacles for advanced carbon materials and value-added chemicals. This study involved the preparation of kraft lignin (KL) loaded metal–organic framework (ZIF-67) material derived Co nanoparticles carbon using various methods to produce kraft lignin biochar-based carbon materials (Co@NPC-KLB). The novel and advanced carbon materials was utilized for lignin derived bio-oil hydrodeoxygenation to generate high value fuels and chemicals. It could achieve nearly 100 % vanillin (VAN) conversion and 88.49 % 2-methoxy-4-methylphenol (MMP) without the extra hydrogen at 240 °C in ethanol. The results demonstrated that highly active and stable Co nanoparticles, large specific surface area, smaller nano Co nanoparticles, strong metal-support interaction and rich Lewis acid sites on the surface of biochar support exhibited a positive promoting effect on VAN hydrodeoxygenation to generate MMP. Furthermore, density functional theory (DFT) also confirmed that synergistic effect of Co nanoparticles and kraft lignin biochar promoted a high adsorption energy of VAN on the surface of kraft lignin biochar, enhanced the catalytic ability of the hydrodeoxygenation process. This study provided a novel approach for utilizing kraft lignin in preparation functional catalysts, opening up new opportunities for designing efficient biochar-based materials for advanced carbon materials and high-value chemicals. [ABSTRACT FROM AUTHOR]

In this work pyrolysis of palm oil and lignin has been investigated using a two-stage process at 550 °C, with a first step configuration of continuous condensation for vapors and separation of gases, and a second step with distillation of vapors. Experiments were realized as pyrolysis of palm oil, palmitic acid, and Kraft lignin, as well as co-pyrolysis of palm oil/lignin, palmitic acid/lignin and palmitic acid/guaiacol. It has been shown that the addition of lignin improves the quality of palm oil pyrolysis bio-oil, thanks to the conversion of fatty acids coproduct to fatty acid methyl esters (FAME). The production of methyl esters in the reaction environment using palm oil and lignin was studied by conducting experiments with palmitic acid and lignin, as well as palmitic acid and guaiacol (the main product obtained from lignin pyrolysis). The results highlighted that during pyrolysis, the production of FAME is a consequence of a direct esterification reaction on palmitic acid. The formation of FAMEs during pyrolysis presents a promising avenue to optimize the utilization of palm oil by generating FAMEs as supplementary fuel products, Furthermore, it is possible to consider the application of the studied process for the conversion of free fatty acids into FAME. [Display omitted] • The addition of lignin improves the quality of palm oil pyrolysis bio-oil. • GC–MS analyses confirm that liquid contains fatty acid methyl esters. • FAME production in the presence of palm oil and lignin by esterification. • Liquid bio-oil mostly constituted by linear paraffins and olefins. [ABSTRACT FROM AUTHOR]

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

The current work examined the properties and thermal decomposition mechanism of a double-base propellant comprising nitrocellulose (NC), diethylene glycol dinitrate (DEGDN), and organic stabilizers. To achieve this objective, a comprehensive analysis was conducted on the influence of stabilizers, namely 2-nitrodiphenylamine (2-NDPA), 1,3-dimethyl-1,3-diphenylurea (MC), and kraft lignin, on the characteristics and pyrolysis gases of NC/DEGDN. Experimental findings demonstrated that kraft lignin has a good stabilizing efficiency, similar to that of 2-NDPA and MC stabilizers. Moreover, differential scanning calorimetry (DSC) experiments revealed that the incorporation of MC, 2-NDPA, and Kraft lignin has increased the maximum peak temperature of the main thermolysis process from T peak = 192.1 °C for NC/DEGDN baseline to T peak = 194.5 °C for NC/DEGDN/MC, T peak = 193.3 °C for NC/DEGDN/2-NDPA, and T peak = 194.3 °C for NC/DEGDN/Kraft lignin. In addition, differences in the stabilization mechanism for each stabilizer were examined using thermogravimetry connected to an infrared spectroscopy (TGA-FTIR). The obtained findings highlighted the discernible influence of stabilizer types on the gaseous products of NC/DEGDN propellant, particularly elucidating their effects on the intensity and type of nitrogen oxides generated throughout the pyrolysis process. [Display omitted] • The effect of organic stabilizers on the characteristics of NC/DEGDN propellant was investigated. • The pyrolysis mechanism of NC/DEGDN/stabilizers propellants was elucidated for the first time. • Hyphenated thermogravimetry-infrared spectroscopy technique was used to identify the pyrolysis gases. • Kraft lignin has shown great potential for being applied as an efficient stabilizer for nitrate esters. [ABSTRACT FROM AUTHOR]

In this study, the effect of oxophilic metal ions (Mo, Zr, and Ti) loaded Ni/γ-Al 2 O 3 (Al) catalysts was explored for the first time for the hydrothermal liquefaction of kraft lignin using IPA for 30 min/280 °C. The liquefaction of lignin was noticed to be 65.4 wt% with 10 wt% loaded Ni/Al with an 81.3% total conversion. The performance of Ni/Al was enhanced remarkably by using the oxophilic metal ions as promoters owing to an increase in the Lewis character of the catalyst's surface. The bio-oil yield was a maximum of 72 wt% with a 91.5% conversion using 3 wt% loaded Ti–10Ni/Al. The different alcoholic solvents such as methanol, ethanol, and IPA were also examined for the same. However, the best liquefaction was noticed with IPA owing to better H-donor tendency. Additionally, a series of IPA-water co-solvent examinations attributed to a significant improvement in the liquefaction to 74.8 wt% (50:50) IPA-water system. The optimum catalyst 10Ni–3Ti/Al was tested for four catalytic cycles, which indicated a slight loss in the catalytic activity because of blockage of the catalytic active site by char deposition. The GC-MS investigation of optimum catalytic bio-oil showed the highest selectivity of acetosyringone (68.5%) and 2-methoxy-phenol (22.8%), which was observed to be only 30.1 and 5.1% for non-catalytic bio-oil. The 1H NMR and FT-IR investigation of raw lignin and bio-oil proved the breakage of lignin's 3D structure into respective G-and S-type monomeric compounds. Additionally, catalysts were characterized using the XRD, BET, and XPS analysis. [Display omitted] • Ni/γ-Al 2 O 3 catalyst was examined for hydrothermal liquefaction of kraft lignin. • The oxophilic metal (Mo, Zr, and Ti) promoter affect the liquefaction significantly. • Maximum bio-oil yield (74.8 wt%) was observed with 10Ni–3Ti/Al catalyst. • IPA and water (50/50) co-solvent exhibited the remarkable effect for liquefaction. • Acetosyringone (68.5%) was detected as a major selective syringyl phenol. [ABSTRACT FROM AUTHOR]

To valorize kraft lignin, hydroxymethylation and sulfonation were applied on this under-utilized, but vastly available, material. The hydroxymethylation pretreatment was conducted as means to improve the reactivity of lignin. The sulfonation of hydroxymethylated kraft lignin was investigated by sulfuric acid and sodium sulfite treatments under various conditions. The modified lignin samples were characterized for their charge density, solubility, elemental components, and molecular weights. The results showed that the hydroxymethylation facilitated the sulfonation by sodium sulfite, yielding a product (SSH-lignin) with the charge density of -1.2 meq/g and water solubility of 10 g/L under the conditions of Ns2SO3/lignin molar ratio of 0.49 mol/mol, 95°C and 3 h. On the other hand, hydroxymethylation hindered the sulfonation of lignin by sulfuric acid, yielding a product (SAH-lignin) with the charge density of -0.46 meq/g and solubility of 0.9 g/L under the conditions of H2SO4/lignin molar ratio of 14.8 mol/mol, 80 °C and 1 h. The SSH-lignin had a high adsorption on kaolinite (17 mg/g) at a lignin concentration of 40 g/L. The sulfonated lignins were also found to be effective coagulant for the cationic dye ethyl violet.

The main objective of this work was to assess Eucalyptus globulus lignin as an adsorbent and compare the results with kraft lignin, which has previously been demonstrated to be an effective adsorbent. Eucalypt lignin was extracted (by the dioxane technique), characterised, and its adsorption properties for Cr(VI) ions were evaluated. The monomeric composition of both types of lignin indicated a high content of guaiacyl (G) and syringyl (S) units but low content of p-hydroxyphenyl (H), with an H:G:S ratio of 1:50:146 (eucalypt lignin) and 1:16:26 (kraft lignin), as determined by Py-GC/MS. According to elemental analysis, sulphur (2%) and sodium (1%) were found in kraft lignin, but not in eucalypt lignin. The adsorption capacity of the eucalypt lignin was notably higher than the kraft lignin during the first 8 h, but practically all the ions had been absorbed by both the eucalypt and kraft lignin after 24 h (93.4% and 95%, respectively). Cr(VI) adsorption onto both lignins fitted well using the Langmuir adsorption isotherm model, with capacities of 256.4 and 303.0 mg/g, respectively, for eucalypt and kraft. The study’s overall results demonstrate the great potential of eucalypt lignin as a biosorbent for Cr(VI) removal from aqueous solutions.

The utilization of lignin from different lignocellulosic biomass is the hot topic for the biorefinery of biomass. In this paper, magnetic lignin nanoparticles (MLN) were prepared by kraft lignin from bamboo residue and Fe3O4 with different ratios via Mannich reaction. The surface morphology and structure of magnetic lignin were characterized and analyzed by X-ray powder diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy, which confirmed that the MLN were successfully prepared. The performance of MLN adsorbents was evaluated by adsorbing Congo red solution at different initial concentrations and contact times. The results showed that Fe3O4@lignin (1:0.5) had the best adsorption effect on Congo red solution. When the concentration of Congo red reached 0.6 g/L, Fe3O4@lignin (1:0.5) had the best adsorption effect on Congo red, reaching 95.5% in only 30 min. As lignin is modified by Fe3O4, it can be recovered by magnetic substances after adsorption and has good reuse performance. The results of adsorption kinetics and adsorption isotherm showed that except for the adsorption process of Fe3O4@lignin (1:0.5), which is consistent with the chemical adsorption of the multimolecular layer, the adsorption process of other adsorbents is in accordance with the chemical adsorption of the monomolecular layer. In terms of environmental protection and adsorption efficiency, and MLN has become an ideal adsorbent for Congo red dyes due to its simple preparation, superior performance, and convenient recovery.

Sulfomethylation of radiata pine kraft lignin was performed using formaldehyde and sodium sulfite under alkaline conditions to determine its potential as a mineral depressant for the separation of molybdenite and chalcopyrite by froth flotation. Optimal conditions for the sulfomethylation reaction were 20% (w/w) Na2SO3 at 130 °C for 4.2 h, which resulted in lignin with a sulfonate content of 2.2 mmol/g. Microflotation assays showed that the optimized sulfomethylated kraft lignin (OSKL) depressed the molybdenite in flotation by 93% using 200 mg/L OSKL, while only 5% chalcopyrite depression was achieved. The performance of OSKL was compared with those of commercial lignosulfonates, and the OSKL displayed a better ability to separate molybdenite and chalcopyrite, even at lower concentration doses. FTIR and 1H-NMR analyses showed that sulfonic groups were incorporated into the C5 position of the aromatic ring and into the aliphatic chain of the OSKL. The hydroxymethyl content of the OSKL was increased, and most ß-O-4', ß-1' and ß-5' bonds were broken, with the exception of the ß-ß' bond. Sulfomethylation gives kraft lignin the chemical characteristics of a wood-based molybdenite depressant, making it an alternative to current reagents used in the chalcopyritemolybdenite flotation process. [ABSTRACT FROM AUTHOR]

This work offers a facile fabrication method for lignin nanocomposites through the assembly of kraft lignin onto magnetic nanoparticles (Fe 3 O 4) based on pH-driven precipitation, without needing organic solvents or lignin functionalization. Kraft lignin@Fe 3 O 4 multicore nanocomposites fabrication proceeded using a simple, pH-driven precipitation technique. An alkaline solution for kraft lignin (pH 12) was rapidly injected into an aqueous-based Fe 3 O 4 nanoparticle colloidal suspension (pH 7) under constant mixing conditions, allowing the fabrication of lignin magnetic nanocomposites. The effects of increasing lignin to initial Fe 3 O 4 mass content (g/g), increasing in ratio from 1:1 to 20:1, are discussed with a complete chemical, structural, and morphological characterization. Results showed that nanocomposites fabricated above 5:1 lignin:Fe 3 O 4 had the highest lignin coverage and content (>20%), possessed superparamagnetic properties (Ms ≈ 45,000 A·m2/kg2); had a negative surface charge (−30 mV), and formed multicore nanostructures (D H ≈ 150 nm). The multicore lignin@Fe 3 O 4 nanocomposites allowed rapid magnetically induced separations from suspension. After 5 min exposure to a rare-earth neodymium magnet (1.27 mm × 1.27 mm × 5.08 mm), lignin@Fe 3 O 4 nanocomposites exhibited a maximum methylene blue removal efficiency of 74.1% ± 7.1%. These nanocomposites have potential in magnetically induced separations to remove organic dyes, heavy metals, or other lignin adsorbates. [Display omitted] • Kraft lignin@Fe 3 O 4 nanocomposites were prepared via a pH-driven aqueous-based method. • A multicore structure was obtained with Fe 3 O 4 nanoclusters and lignin shells. • Above a 5:1 lignin:Fe 3 O 4 mass ratio, nanocomposite properties remain unchanged. • Methylene blue was adsorbed and magnetically separated with a low strength magnet. [ABSTRACT FROM AUTHOR]

Polyurea microcapsules containing oxyfluorfen herbicide were synthesized by interfacial polymerization reaction between toluene diisocyanate and ethylene diamine at various core to shell ratios using green solvent N-N-dimethyldecanamide as carrier medium and using biodegradable PVA203S and Kraft lignin grade (varying molecular weight) as the emulsifying agent. The study was done to understand the effect of stirring rate on preparing microcapsules and find out how the process conditions changed the attributes of microcapsules such as particle size distribution, encapsulation efficiency and release kinetics. The formation of capsules was confirmed by FT-IR, SEM and TGA. The study indicated that the encapsulation efficiency decreased with increasing core to shell ratio. The change in release kinetics was based on the stirring rate and was dependent on the pH of release medium. Particle size distribution was influenced by the agitation speed during formation of emulsion. Kraft lignins of varying molecular weight were used to synthesize the polyurea capsules. It was found that capsules with high molecular weight lignin showed slow and sustained release. Synthesized polyurea capsules was subjected to safety study on paddy crop and compared with commercially available oxyfluorfen and was found to be safe for use on paddy crop. [ABSTRACT FROM AUTHOR]

To improve the reactive sites of kraft technical lignin, a deep eutectic solvent (DES) composed of ZnCl2 / lactic acid was used to pretreat kraft lignin from coniferous wood. The modified and unmodified lignin were used to replace different proportions of phenol (50%, 60%, and 70%) to prepare the lignin-phenol-formaldehyde (LPF) adhesive. The phenolic hydroxyl content of DES-treated lignin increased from 3.12 wt% to 3.93 wt% and methoxy content decreased from 11.83 wt% to 6.64 wt% under optimized experimental conditions. The bond strength of LPF adhesive prepared by DES reagent activated lignin was higher than that of the control sample. When the substitution degree of modified lignin for phenol reached 70%, the bond strength of the plywood prepared by the DESpretreated lignin was 0.79 MPa and the free formaldehyde content was 0.28%, which met the requirements of the Chinese national standard GB/T 9846 (2015). However, the viscosity was higher than the control sample, and results indicate that DES reagent modification cannot improve the viscosity of LPF resin. [ABSTRACT FROM AUTHOR]

Carbon foams have been prepared using Kraft lignin as the solely resource. No catalysts, foaming/blowing agents, surfactants, and/or crosslinking agents are used for the foam preparation. The process includes pressing carbon foam precursors into molds followed by formation of lignin foam through heating and carbonization/graphitization of the lignin derived foams. The resultant lignin carbon foam (LCF) has an open-cell structure with densities ranging from about 0.18 g/cm3 to 0.68 g/cm3. The compressive strengths of LCFs increase with increasing of bulk density, from 7.03 ± 1.25 MPa of LCF1 to 30.16 ± 2.41 MPa of LCF7, and thermal conductivity is strongly influenced by the bulk density with increase from 0.21 ± 0.02 W/(m·K) to 0.75 ± 0.01 W/(m·K). The bulk electrical conductivities of LCF samples increase with increasing of bulk densities from 701 S/m to 2031S/m. The LCF samples were evaluated for resistance to fire and native subterranean termites. LCF samples exhibit excellent fire resistance, no damage occurred when the LCF sample was exposed to an oxyacetylenic flame in air over 1050 °C for more than 3 min. Termite testing showed no degradation to the LCF samples after the evaluation.

To improve the reactivity of lignin for incorporation into high value polymers, the introduction of amines via Mannich reaction is a commonly used strategy. During this functionalization reaction, intra- as well as intermolecular lignin–lignin crosslinking occurs, which can vastly change the elastic properties of the lignin, and therefore, the properties of the resulting polymer. Therefore, the molecular structure of the amine that is used for such a lignin functionalization may be of great importance. However, the relationship between the molecular structure of the amine and the elastic properties of the lignin-based polymer that is generated thereof, has not been fully understood. Herein, this relationship was investigated in detail and it was observed that the molecular flexibility of the amines plays a predominant role: The use of more flexible amines results in an increase in elasticity and the use of less flexible amines yields more rigid resin material. In addition to the macroscopic 3-point bending flexural tests, the elastic modules of the resins were determined on the nanometer scale by using atomic force microscopy (AFM) in the PeakForce tapping modus. Thus, it could be demonstrated that the intrinsic elasticities of the lignin domains are the main reason for the observed tendency. [ABSTRACT FROM AUTHOR]

Fiber treatments to enhance interfacial adhesion in natural fiber-reinforced composites generally induce the use of many chemicals. To address this issue, the present work aimed to develop innovative and ecological fiber treatments to produce 100%-green composites, by investigating interfacial adhesion between modified flax fibers and polylactic acid (PLA) using lignin and tannin, two types of eco-friendly polyphenolic compounds derived from waste or paper industry byproducts. The surface modification of flax fibers was performed using a dip-coating method and solutions of condensed tannin or Kraft lignin at different concentrations ranging from 1% to 7% (wt/V). The results showed that the use of coating solutions composed of 1% (wt/V) tannin or lignin significantly improved the interfacial adhesion of composites. Tannin showed better compatibility with PLA and flax fibers with a 17% and 29% increase in the ultimate flexural strength and interlaminar shear strength of the composites, respectively. These results were explained by tannin higher concentration of hydroxyl functions as compared to lignin and thus, good reactivity with cellulose and PLA. Coating solutions rich in lignin or tannin have reduced the mechanical properties of composites due to the thicker coating layers and the migration of lignin or tannin molecules into the PLA bulk. [ABSTRACT FROM AUTHOR]

Chemical coprecipitation technique is proven to be a beneficial method to prepare uniformly mixed catalyst metal and Kraft lignin precursors. Coprecipitation is a simple, yet very complex process which is highly sensitive to the reaction conditions, particularly temperature. In an exothermic coprecipitation process, the reaction rate can become uncontrollable over certain temperatures which could lead to a thermal runaway reaction. In this work, metal-lignin nanocomposites were synthesized by coprecipitation of metal (M) salts and Kraft lignin. Kraft lignin and metal salts were dissolved in organic solvents and DI water, respectively, to make lignin solution/suspension and metal salt aqueous solution. The aqueous solutions of metal salts were then added to the lignin solutions/suspensions and mixed well, resulting in chelation of transition metal ions to the functional groups of lignin chains and co-precipitation of metal-lignin composites from the solvents. To develop a safe process for producing M-lignin composites in a large volume, potential reactions, exothermic or endothermic processes, hazards gases, and volatiles were evaluated during the coprecipitation process. The effects of transition metal type, solvent selection, concentration of metal salts, and initial solution temperature on the interactions between metal ions and Kraft lignin, metal uniformity in the lignin matrix, and morphology of the metal-lignin composites were investigated during the coprecipitation process. Cu, Mo, Ni, and Fe were investigated as the transition metals for the metal-lignin composites. Fenton or Fenton-like reactions were discovered to occur during the Fe- and Cu-lignin coprecipitation process and tremendous heat evolved, which lead to the overshoot of the reaction system temperature in a very short time (i.e. a few seconds). Significant amounts of CO2 and toxic NO2 gasses were released during the coprecipitation process when Fenton or Fenton-like reactions occurred. No interaction or a very weak interaction occurred between lignin and Mo(VI) ions when mixing both solutions. Ni ions were coordinated strongly to oxygen-containing functional groups in lignin, but no Fenton or Fenton-like reaction was detected during Ni-lignin coprecipitation. Fenton reaction or Fenton-like reaction occurred when tetrahydrofuran (THF) and acetone were used to dissolve Kraft lignin, and the reaction became highly fierce and unmanageable with increasing of iron content in the composite. The reaction initialization time was shortened with increase of initial solution temperature and thermal runaway reaction might occur if the initial mixing temperature reached 60 °C or above. [ABSTRACT FROM AUTHOR]

Lignins are promising alternative raw materials for biocomposites due to their renewability, low cost and abundance. In this work, the use of (softwood and hardwood) Kraft lignins in the development of LLDPE/lignin films for agricultural mulch applications is studied. Processable blends were obtained from unmodified softwood lignin (SW) and from hardwood lignin modified by esterification (HWE). LLDPE was pelletized with (2.5%, 5% and 10%) lignin with particle size between 38 and 75 μm and flexible films were blown extruded. Processable extrusion blends showed temperature differences lower than 20 °C between the Tg of lignin and the melting temperature of LLPDE. Films from neat LLPDE and with 2.5% of HWE and up to 5% SW exhibited statistically comparable (≅ 349%) values of ductility. Ester groups present in lignin improve weight loss of lignin-based blends after soil buried test. [ABSTRACT FROM AUTHOR]

We present an approach to overcome the challenges associated with the increasing demand of high-throughput characterization of technical lignins, a key resource in emerging bioeconomies. Our approach offers a resort from the lack of direct, simple, and low-cost analytical techniques for lignin characterization by employing multivariate calibration models based on infrared (IR) spectroscopy to predict structural properties of lignins (i. e., functionality, molar mass). By leveraging a comprehensive database of over 500 well-characterized technical lignin samples - a factor of 10 larger than previously used sets - our chemometric models achieved high levels of quality and statistical confidence for the determination of different functional group contents (RMSEPs of 4-16 %). However, the statistical moments of the molar mass distribution are still best determined by size-exclusion chromatography. Analyses of over 500 technical lignins offered also a great opportunity to provide information on the general variability in kraft lignins and lignosulfonates (from different origins). Overall, the effected savings in analysis time (>7 h), resources, and required sample mass combined with non-destructiveness of the measurement satisfy key demands for efficient high-throughput lignin analyses. Finally, we discuss the advantages, disadvantages, and limitations of our approach, along with critical insights into the associated chemical-analytical and spectroscopic challenges., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Converting industrial/agricultural lignin-rich wastes to efficient, cost-effective materials for electrochemical devices (e.g., fuel cells) can aid in both bio- and energy economy. A major limitation of fuel cells is the weak ion conductivity within the ~2–30-nm thick, ion-conducting polymer (ionomer)-based catalyst-binder layer over electrodes. Here, we strategically sulfonated kraft lignin (a by-product of pulp and paper industries) to design ionomers with varied ion exchange capacities (IECs) (LS x; x = IEC) that can potentially overcome this interfacial ion conduction limitation. We measured the ion conductivity, water uptake, ionic domain characteristics, density, and predicted the water mobility/stiffness of Nafion, LS 1.6, and LS 3.1 in submicron-thick hydrated films. LS 1.6 showed ion conductivity an order of magnitude higher than Nafion and LS 3.1 in films with similar thickness. The ion conductivity of these films was not correlated to their water uptake and IECs. Within the three-dimensional, less dense, branched architecture of LS 1.6 macromolecules, the –SO3H and –OH groups are in close proximity, which likely facilitated the formation of larger ionic domains having highly mobile water molecules. As compared to LS 1.6, LS 3.1 showed a higher glass transition temperature and film stiffness at dry state, which sustained during humidification. On the contrary, Nafion stiffened significantly upon humidification. The smaller ionic cluster within stiff LS 3.1 and Nafion films thus led to ion conductivity lower than LS 1.6. Since LS x ionomers (unlike commercial lignosulfonate) are not water soluble, they are suitable for low-temperature, water-mediated ion conduction in submicron-thick films.

Abstract Environmental friendliness and cost demand the development of lignin-modified phenolic (LPF) resins for application as a binder for carbon-containing refractories (CCRs) production. Moreover, the in-situ graphitization of such resins can produce crystalline carbon, which is an essential component of CCRs. Consequently, this study investigated LPF resins graphitization using ferrocene, boron oxide and boric acid. The modified resins were synthesized using thermally treated kraft lignin based on 1.5 formaldehyde to phenol molar ratio and with up to 30 wt.% lignin as phenol replacement. The resins chemical composition and the structural organization and oxidation resistance of carbons derived from the plain resins and those containing the graphitizing additives were determined. The results showed that ferrocene and the boron compounds could induce graphitic carbon generation when carbonizing LPF resins at 1500 °C for 5 hours. The best graphitization level (73%) was achieved when 10 wt.% boric acid was added to the resin produced with 20 wt.% lignin. Regarding the formulations containing ferrocene, the highest amount of graphitic carbon (48%) was generated when 5 wt.% of this additive was added to the resin synthesized with 10 wt.% lignin. The carbons derived from the formulations containing boron oxide presented the best oxidation resistance.

Maximum utilization of lignocellulosic biomass is contingent upon degrading the recalcitrant lignin polymer. Conventional methods employed in delignification require high inputs of energy and chemicals, resulting in the release of highly toxic effluents. The ability of gut flora of Coptotermes curvignathus in lignin degradation was investigated in this study. Production of ligninolytic enzymes was done in an aerated submerged fermentation system with kraft lignin as sole carbon source. The degradation experiment was carried out for 7 days at 30 °C, pH 7. Three potential lignin degraders identified as Bacillus sp., Lysinibacillus sp. and Acinetobacter sp. were successfully isolated. The bacterial growth and secretion of extracellular ligninolytic enzymes confirmed metabolism of kraft lignin by the identified strains. Lysinibacillus sp., a novel lignin degrader showed highest manganese peroxidase (76.36 ± 15.74 U/L) and laccase activity (70.67 ± 16.82 U/L) after 7 and 6 days of incubation respectively, while maximal activity of lignin peroxidase (262.49 ± 0.92 U/L) was recorded after 7 days in culture supernatants of Bacillus sp. With respect to the activity of the secreted enzymes, the lignin degrading potential of these bacterial strains can be explored in the valorisations of lignocellulosic biomass in industrial processes such as pulping, bioethanol production, fine chemicals and materials synthesis.