Alkali Lignin Research Articles

Oxidative degradation of anionic dyes in wastewater by magnetic lignin micro-nano spheres catalyzed peroxymonosulfate

Lignin has gained significant attention in wastewater treatment due to its abundant resources and good adsorbability. In this work, magnetic lignin micro-nano spheres (Fe3O4@SiO2-LNS) was prepared using alkali lignin as the raw material, and was used as the adsorbent and catalyst to activate peroxymonosulfate (PMS) to build an inhomogeneous catalytic oxidation system (Fe3O4@SiO2-LNS/PMS). The system was then used to remove the stubborn acid blue 9 (AB9) dye in wastewater, and the effects of pH, catalyst dosage, PMS dosage of the system on the removal percentage of AB9 dye and the corresponding degradation mechanism were explored. The results showed that Fe3O4@SiO2-LNS/PMS system had good removal efficiency for AB9 in wastewater, and AB9 dye was completely oxidized and finally degraded into CO2 and H2O. The maximum removal percentage of AB9 was observed when the pH and temperature of the system were 6.0 and 313 K, and the removal percentage of AB9 achieved 100 % when the optimal dosage of Fe3O4@SiO2-LNS and PMS were 3.44 g/L and 53.15 mM, respectively. In addition, Fe3O4@SiO2-LNS had good stability and reusability. This work provides a promising approach for abatement of dyeing wastewater pollution and a new direction for high-value utilization of alkali lignin.

Lignin-derived core-shell flame retardants for fire-safety rigid polyurethane (RPU) insulations

How to ensure the fire safety of rigid polyurethane (RPU) insulation materials remains a challenge. Herein, alkali lignin (AL) and 4,4'-diphenylmethane diisocyanate (MDI) were used as raw materials to construct bio-based cross-linked polyurethane structures on the surface of ammonium polyphosphate (APP) to obtain APP@AL flame retardants. APP@AL was combined with expandable graphite (EG) in varying proportions and applied to rigid polyurethane (RPU) foam to modify its flame retardancy and physico-mechanical characteristics. Compared with untreated RPU, the high interfacial compatibility increased the compressive strength of the flame-retardant RPUs by 10.8%, and the thermal insulation coefficient reached 22.8mW·m−1·K−1. The addition of flame retardant for each flame-retardant RPU was 30wt% of the polymethylene polyphenyl isocyanate. Owing to the P/C/O hybridized char layer in the combustion residues and the capture of gas by EG after expansion, APP@AL/EG not only reached the limiting oxygen index (LOI) of 27.1% but reduced the mean heat release rate and smoke release rate by 70.3% and 58.9%, respectively. This work presented a novel approach to designing environmentally friendly flame retardants for RPU foams with enhanced fire safety and superior overall performance. Additionally, it offers a novel strategy for the high-value conversion of lignin.

Lignin-Chitosan-Based Bioplastics from Oil Palm Empty Fruit Bunches for Seed Coating

Lignin is a hydrophilic-hydrophobic biopolymer known for its antioxidant activity, which could make it a suitable coating material. In this research, a bioplastic based on the combination of alkali lignin from oil palm empty fruit bunches and chitosan was developed for seed coating via a dipping method. Chili seeds were used as a model in this study. The bioplastic was prepared via a modified solvent casting method at lignin:chitosan:glycerol weight ratio of 0.25:1.0:0.2. For the isolated lignin, the antioxidant activity, total phenolic content, methoxyl content, and equivalent weight were measured; for the bioplastic lignin, contact angle, swelling, antioxidant activity, mechanical properties and biodegradability were assessed. The presence of the coating was observed by Cryo-EM while the suitability of lignin-chitosan bioplastics for seed coating was evaluated by the germination rate, root length, height, and dry weight of the sprouts. The results showed that isolated lignin enhances the antioxidant activity of the lignin-chitosan liquid bioplastic by up to 84%. The addition of isolated lignin increased the contact angle and reduced the swelling rate of the bioplastics. The presence of lignin increases the tensile strength and elastic module in the biofilm. The microscopical investigation demonstrated the presence of the coating and no alteration in the seed surface morphology under the coating layer. The application of chitosan-lignin-based bioplastics maintain the quality of the seed during its shelf life. The germination rate of the coated chili seeds increased by up to 100% after one week of storage and 40–80% after five weeks of storage.

Flexible and highly selective NO2 gas sensor based on direct-ink-writing of eco-friendly graphene oxide for smart wearable application

Nitrogen dioxide (NO2) is a major cause of respiratory disorders in outdoor and indoor environments. Real-time NO2 monitoring using nonintrusive wearable devices can save lives and provide valuable health data. This study reports a room-temperature, wearable, and flexible smart NO2 gas sensor fabricated via cost-effective printing technology on a polyimide substrate. The sensor uses alkali lignin with edge-oxidised graphene oxide (EGO-AL) ink, demonstrating a sensitivity of 1.70% ppm⁻1 and a detection limit of 12.70 ppb, with excellent selectivity towards NO2. The high sensing properties are attributed to labile oxygen functional groups from GO and alkali lignin, offering abundant interacting sites for NO2 adsorption and electron transfer. The sensor fully recovers to the baseline after heat treatment at 150 °C, indicating its reusability. Integration into lab coats showcased its wearable application, utilising a flexible printed circuit board to wirelessly alert the wearer via cell phone to harmful NO2 levels (>3 ppm) in the environment. This smart sensing application underscores the potential for practical, real-time air quality monitoring, personal safety enhancement, and health management.

Exploration of steel slag by lignin and sodium citrate modification for mechanical properties and stability of steel slag-cement cementitious materials

Steel slag is produced globally in huge annual quantities. How to achieve its large-scale utilization is a question that researchers have been exploring. In this work, sodium citrate (SC) was used as a linker to modify Steel slag (SS) with alkali lignin (AL). And steel slag cement cementitious materials (CSS) were prepared with 10% replacement ratio. The effects of AL and SC on CSS were investigated by X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermo-gravimetric analysis (TG/DTA) etc. The results indicated that AL successfully loaded on the surface of SS. For CSS, as the degree of modification increased, the standard consistency water consumption of CSS decreased from 27% to 23.5%. During the hydration of CSS, its main hydration product was Ca(OH)2, the suitable amounts of AL and SC can stimulate the activity of SS. In addition, SS modification could improve the stability of CSS. The results of Ray's clamp method showed that the addition of AL and SC made the expansion of CSS reduced from 1.5 to 0. The 3 d and 28 d of CSS maximum flexural strengths were 5.42 MPa and 8.61 MPa and the maximum compressive strengths were 22.96 MPa and 49.15 MPa, respectively. This was an increase of 36.67% and 48.27% respectively. Therefore, the combination of AL and SS can not only effectively solve the problem of AL resource utilization, but also is expected to realize the practical application of SS in cement cementitious materials. It has good social and environmental benefits.

Sustainable strategy for lignin etherification and its promotion of anti-UV aging PLA biocomposite

Achieving efficient modification of both phenolic (Phe)-OH and aliphatic (Aliph)-OH groups in lignin simultaneously via sustainable method, remained a significant challenge. In this study, a series of highly hydroxyl-substituted alkali lignin phenyl propylene ketone ethers (ALK) were obtained under 50 °C without any by-products via the mild and sustainable hydroxyl-yne click reaction method. Notably, phenolic (Phe)-OH content of lignin decreased from 4.12 mmol g−1 to 0.07 mmol g−1 with a conversion rate of 98 %, while the aliphatic (Aliph)-OH content of lignin decreased from 2.57 mmol g−1 to 0.10 mmol g−1 with a conversion rate of 96 %. Owing to the efficient etherification, ALK showed excellent organic solvent (such as trichloromethane, DCM, THF, and acetone) solubility, which thereby improving the interfacial compatibility between ALK and PLA matrix. 3 wt% ALK obviously enhanced the mechanical properties of ALK/PLA biocomposite films, with the yield strength, breaking strength, and Young’s modulus improving by 114.2 %, 30.7 % and 250.2 %, respectively. Additionally, due to the newly introduced vinyl ether bonds (−C–O–CC–) in ALK by hydroxyl-yne click reaction, only 1 % ALK could endow ALK/PLA biocomposite with excellent UV shielding (100 %), high transmittance (84.3 %) and Anti-UV aging property. The yield strength and Young’s modulus represented an increase of 209 % and 86 %, respectively, even after 3 h of UV-irradiation. This study presents an environmentally friendly lignin functionalization method that unleashes the inherent Anti-UV aging properties of lignin, opening new avenues for the development of high-performance lignin-based composites.

Sustainable Nanofluids Constructed from Size-Controlled Lignin Nanoparticles: Application Prospects in Enhanced Oil Recovery.

Lignin, a widely available, cost-effective, and structurally stable natural polymer, has recently attracted significant attention due to its diverse potential applications. A promising approach is to prepare lignin nanoparticles (LNPs) as a substitute for conventional nanoparticles to fulfill a variety of functions. In this study, LNPs with controlled size, regular morphology, and excellent dispersibility were synthesized by using industrial alkali lignin. The antisolvent method was employed, utilizing an aqueous solution of the anionic surfactant sodium apolyolefin sulfonate (AOS) as the antisolvent. Subsequently, the prepared LNPs were used to formulate nanofluids in combination with AOS and nonionic surfactant coconut diethanolamide (CDEA). The incorporation of LNPs has significantly enhanced the interfacial activity of the resulting nanofluids, thereby improving their emulsion stabilization, spreading on quartz surfaces, and oil droplet removal capabilities, which establish a strong foundation for the AOS/CDEA/LNPs nanofluid to achieve high performance in enhanced oil recovery (EOR), which was validated through microscopic visual physical model experiments. The quartz crystal microbalance with the dissipation monitoring (QCM-D) technique was employed to investigate the adsorption of surfactants onto quartz surfaces. It was found that the incorporation of LNPs significantly reduces the adsorption loss of surfactants, presenting a potential solution to overcome the challenges associated with surfactant adsorption in chemically enhanced oil recovery (EOR) processes, such as high cost and unreliable efficiency. This study reveals the good performance of LNPs/surfactant nanofluids and provides a potential approach to the advancement of green, sustainable, and intelligent EOR technologies.

Enhancing PVA mulching films: Leveraging modified lignin as a bio-based crosslinking agent for improved mechanical strength, UV barrier, and biodegradability

In contemporary agriculture, eco-friendly mulching films present a promising alternative to conventional plastic mulching films. However, their potential is constrained by challenges related to limited biodegradation and barrier performance. Addressing these limitations, innovative lignin-carboxylated materials were employed as bio-based crosslinking agents to enhance diverse properties in the fabrication of PVA films. Alkali lignin was modified with diethylenetriaminepentaacetic acid (DTPA) to enhance its chemical reactivity. The abundance of carbonyl groups in modified lignin (Lig-DTPA) plays a significant role in establishing strong compatibility with PVA through covalent bonds. This interaction yielded remarkable enhancements, elevating both tensile strength and tensile modulus by an impressive 50.9 % and 60.1 %, respectively. The introduction of Lig-DTPA at 3 % into the PVA composite films resulted in excellent UV-blocking properties. Moreover, at 3 % ratios, the presence of lignin became visibly dispersed as clear spots across the film, indicating a relatively uniform state within the matrix. The study revealed a direct correlation: as the lignin content increased, the film exhibited heightened water solubility and enhanced biodegradability. The PVA/Lig-DTPA film displays promising potential for utilization as a mulching film material, offering anti-ultraviolet functionality and a high degradation rate. Furthermore, its versatility extends to potential applications in packaging materials, including seedling bowls, transplanting pots, and coating films for transportation purposes.

A high-efficiency strategy for fruit preservation using green, natural raw materials

Straw is an abundant renewable biomass resource material. Lignin contained in straw is a unique natural aromatic compound in nature. At present, it is urgent to find ways to realize the higher value of natural lignin resources. In this study, alkali lignin was separated from rice straw by hydrothermal method in NaOH solution, which was prepared lignin nanoparticles by a simple green anti-solvent method. The obtained lignin nanoparticles had excellent anti-tyrosinase activity (IC50 = 0.329 mg mL−1) and anti-oxidation performance (IC50 = 0.0451 mg mL−1). Meanwhile, through the analysis of tyrosinase inhibition kinetics, it is concluded that the tyrosinase inhibition by lignin nanoparticles belongs to mixed inhibition. The affinity of lignin nanoparticles to the free enzyme is greater than that of enzyme and substrate complex. In addition, lignin nanoparticles were added to chitosan solution for compounding, then the composite films for fruit preservation were prepared by casting method. The experimental results show that the composite membrane can effectively extend the shelf life of fruits, which is expected to achieve a broader application in the field of fruit preservation and food packaging.

Lignin Nanoparticles as pH-responsive Nanocarriers for Gastric-Irritant Oral Drug Aspirin.

Although lignin is one of the most naturally abundant biopolymers, the overall status of its utilization has long been subpar. The ability of Lignin to readily self-assemble into nanoparticles, along with its good biocompatibility and minimal toxicity, makes it a perfect agent for nanocarriers and drug delivery. Hence, in this study, we have attempted to examine lignin nanoparticles (LNPs) as an efficient pH-responsive nanocarrier for gastric-irritant oral NSAID, aspirin. Alkali lignin (AL) was extracted from rice straw via alkaline treatment, and the lignin nanoparticles were synthesized from lignin using the acid precipitation method. The average particle size was 201.37 ± 1.20 nm, and the synthesized LNPs exhibited a spherical shape and smooth outer surface along with high polydispersity (PDI= 0.284 ± 0.012). The LNPs showed moderate hemocompatibility during in vitro hemolysis studies. The nanoparticles presented nearly similar chemical structures to the AL from which they were developed, and the FT-IR absorption spectra confirmed the similarity of this chemical structure to the LNPs and AL. Aspirin was successfully loaded into the LNPs with a satisfactory drug loading value of 39.12 ± 1.50 and an excellent encapsulation efficiency value of 91.44 ± 0.59. Finally, the LNPs were capable of protecting the loaded drug at the acidic pH of the stomach (1.2) with just 29.20% release of the loaded aspirin after 10 h of observation in vitro. Contrarily, the LNPs were capable of rapidly releasing the aspirin at the basic pH of the intestine (7.4) with nearly 90% release of the loaded drug after 10 h observation in vitro. The basic pH of the intestine might lead to gradual dissociation of the LNPs followed by swift release of the loaded cargo. These findings substantiate that the LNPs carry the potential to be an apt and safe nanocarrier for oral drugs like aspirin as well as parenteral drugs, and LNPs can be utilized as an efficient alternative to enteric coating.

Synergistic magnetic Cu-Fe catalysts on N-doped biochar for efficient alkali lignin catalytic depolymerization into monophenols

Alkali lignin, a major by-product of papermaking, poses disposal challenges, hindering the full valorization of lignocellulose in sustainable biorefineries. One-pot lignin catalytic depolymerization (LDP) in water offers a promising route for producing valuable phenolic compounds. This study reports the successful synthesis of in-situ N-doped biochar supported CuxFey catalysts (CuxFey/N-BC) via a one-step carbothermal reduction method, enabling LDP in water without the need for external hydrogen, additives, alcohol solvent, or co-catalysts. Notably, the Cu5Fe1/N-BC could achieve remarkable catalytic performance under mild reaction conditions (280 °C, 6 h, 18 mL water), yielding 80.84±2.23 mg/g of monophenol, 56.17±1.32 % of bio-oil, and a lignin conversion rate of 80.66±0.73 %. This significantly surpassed the performance of monometallic catalysts and bare biochar. The synergistic effects of intermetallic interactions and nitrogen doping were proposed to create abundant active sites and rich pore structures, promoting efficient LDP reactions. Furthermore, the Cu5Fe1/N-BC exhibited excellent recyclability, with minimal activity loss (2.79 %) per cycle, due to its strong magnetism and favorable interactions. Mechanism investigation revealed that the Cu5Fe1/N-BC efficiently cleaved the C-O and C-C bonds in lignin, and led to the targeted production of guaiacyl phenols. This study provides valuable insights and practical strategy for valorizing lignin into valuable chemicals, advancing its utilization in various applications.

Life cycle assessment and design of LignoBlock: A lignin bound block on the path towards a green transition of the construction industry

Lignin-based biopolymer-bound soil composites (BSCs) are a new class of sustainable construction materials that utilize a bio-based biopolymer — lignin — as a binder. Prior use of lignin suggests that lignin is a promising candidate for the development of bio-based construction materials. Inspired by these applications, lignin-based BSCs were developed using lignoboost lignin, lignoforce lignin, alkali lignin, and hydrolysis lignin. Uni-axial compressive testing of lignin-based BSC shows that the compressive strength for these BSCs range from 1.6–8.1 MPa, which makes them appropriate for low compressive strength construction applications. We performed a life cycle assessment (LCA) of lignin-based BSC, with the functional unit being a CMU-sized block (V=6423cm3). The major advantage of BSC lies in the elimination of ordinary portland cement, which is common to many construction materials, including many forms of concrete. Furthermore, the use of lignin in lignin-based BSC results in carbon sequestration (lignin ≈ 60 wt% carbon), potentially making construction materials made from lignin-based BSC carbon negative. Additionally, a design guide for estimating the life cycle carbon footprint of lignin-based BSC for a required compressive strength was developed. By utilizing the results from material tests and the LCA, designers are now able to use lignin effectively in construction applications, as they can now design lignin-based BSC for a target compressive strength with a full understanding of the life cycle carbon footprint implications.

One-Pot Synthesis of Biochar from Industrial Alkali Lignin with Superior Pb(II) Immobilization Capability.

This study synthesized biochar through a one-pot pyrolysis process using IALG as the raw material. The physicochemical properties of the resulting biochar (IALG-BC) were characterized and compared with those of biochar derived from acid-treated lignin with the ash component removed (A-IALG-BC). This study further investigated the adsorption performances and mechanisms of these two lignin-based biochars for Pb(II). The results revealed that the high ash content in IALG, primarily composed of Na, acts as an effective catalyst during pyrolysis, reducing the activation energy and promoting the development of the pore structure in the resulting biochar (IALG-BC). Moreover, after pyrolysis, Na-related minerals transformed into particulate matter sized between 80 and 150 nm, which served as active adsorption sites for the efficient immobilization of Pb(II). Adsorption results demonstrated that IALG-BC exhibited a significantly superior adsorption performance for Pb(II) compared to that of A-IALG-BC. The theoretical maximum adsorption capacity of IALG-BC for Pb(II), derived from the Langmuir model, was determined to be 809.09 mg/g, approximately 40 times that of A-IALG-BC. Additionally, the adsorption equilibrium for Pb(II) with IALG-BC was reached within approximately 0.5 h, whereas A-IALG-BC required more than 2 h. These findings demonstrate that the presence of inorganic mineral components in IALG plays a crucial role in its resource utilization.

Structural optimization of the NiFe2O4 spinel catalyst aimed at efficient electrocatalytic C-O bond cleavage of lignin

The intricate structure of lignin poses significant challenges to its high-value utilization. Electrocatalytic conversion of lignin into valuable aromatic compounds using spinel catalysts under mild conditions is a promising approach. The electrochemical conversion of lignin and its model compounds was conducted using Ni-Fe spinel catalysts, achieving selective cleavage of the C-O bond in lignin model with 72 % phenol selectivity and 82 % conversion. Additionally, efficient electrochemical cleavage of the C-O bond was achieved using alkali lignin. Structural characterization and theoretical calculations revealed that the Ni-Fe spinel catalyst exhibited a uniform electron distribution, enhancing the adsorption of the C-O bond and lowering the activation free energy associated with C-O bond cleavage. Moreover, the heterogeneous interface of NiFe2O4 further accelerated the reaction kinetics. This study represents a significant breakthrough in active site identification and mechanistic analysis, facilitating the selective conversion of lignin and providing an efficient method for lignin depolymerization.

Development of Methylene Bis-Benzotriazolyl Tetramethylbutylphenol-grafted lignin sub-microspheres loaded with TiO2 for sunscreen applications

Lignin serves as a promising Ultraviolet (UV) absorber within sunscreen industry. However, the commercial development of lignin-containing sunscreens faces challenges due to their low sun protection factor (SPF) and dark color in cosmetics industry. In this study, dual modifications on the chemical and physical structures of lignin were conducted to address these challenges. Initially, methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) was grafted onto alkali lignin (AL) through an atom transfer radical polymerization reaction, resulting in a polymer of AL-graft-MBBT3 (AL-g-MBBT3). The sunscreen prepared with 10 % AL-g-MBBT3 displays outstanding sun protection performance with a SPF of 42.93 and a light color with a color difference value (ΔE) of 45.6, in contrast to 10 % AL with a SPF of 4.74 and a ΔE value of 49.5. Subsequently, AL-g-MBBT3 was transformed into normal submicron spheres (AL-g-MBBT3 N) and TiO2-loading submicron spheres (AL-g-MBBT3/TiO2). The sun protection performances of 10 % AL-g-MBBT3 N@C and AL-g-MBBT3/TiO2@C sunscreens obviously surpass that of AL-g-MBBT3@C sunscreen, achieving SPFs of 60.38 and 66.20, respectively. Additionally, there is a considerable improvement in the color of these sunscreens, with ΔE values of 41.8 and 36.3, respectively. These results provide valuable insights into exploring lignin's high-value applications in sunscreen.

Mussel-Bioinspired Lignin Adhesive for Wearable Bioelectrodes.

As a natural "binder," lignin fixes cellulose in plants to foster growth and longevity. However, isolated lignin has a poor binding ability, which limits its biomedical applications. In this study, inspired by mussel adhesive proteins, acidic/basic amino acids (AAs) are introduced in alkali lignin (AL) to form ionic-π/spatial correlation interactions, followed by demethylation to create catechol residues for enhanced adhesion activity. Atomic force microscopy reveals that catechol residues are the primary adhesion structures, with basic AAs exhibiting superior synergistic effects compared to acidic AAs. Demethylated lysine-grafted AL exhibits the strongest adhesion force toward skin tissue. Molecular dynamic simulation and density functional theory calculations indicate that adhesion against skin tissue mainly results from hydrogen bonds and cation-π interactions, with the adhesion mechanism being based on the Gibbs free energy of the Schiff base reaction. In summary, a biomimetic electrode based on lignin inspired by mussel adhesive proteins is prepared; the presented method offers a straightforward strategy for the development of biomimetic adhesives. Furthermore, this mussel-inspired adhesive can be used as a wearable bioelectrode in biomedical applications.

Polyvinylidene fluoride-alkali lignin blend: A new candidate for membranes development

New blend membranes consisting of a tuned ratio of polyvinylidene fluoride (PVDF) and alkali lignin (AL) were studied. Through the use of a green solvent like dimethyl sulfoxide, effective mixing between PVDF and AL was achieved, leading to the development of highly hydrophilic membranes with robust mechanical stability. Characterization methods confirmed the suitability of the blend for membrane preparation and its hydrophilic nature.A key aspect of the strategy involved hydrophilizing PVDF during the preparation process by blending it with AL in the pot. This approach aimed to streamline production by reducing the number of steps compared to post-treatment methods such as grafting or coating. The presence of hydrophobic/hydrophilic groups in the AL structure addressed the challenge of compatibility between PVDF and conventional hydrophilic polymers, enhancing interaction between the components.The resulting hydrophilic material exhibited improved pure water permeance and demonstrated resistance to irreversible fouling. The membrane's ability to process wastewater streams and its resistance to fouling was demonstrated by separating stable and uniform submicron oil-in-water emulsions with high rejection (>99.9 %) up to a volume reduction factor (VRF) of 7.7.

Tuning the Properties of Polyvinylidene Fluoride/Alkali Lignin Membranes to Develop a Biocatalytic Membrane Reactor for an Organophosphorus Pesticide Degradation.

It has been observed that the immobilization of a phosphotriesterase enzyme (PTE) onto polyvinylidene fluoride (PVDF) membranes significantly decreased the enzyme activity, and this negative effect was attributed to the hydrophobic character of the membrane. The indirect indication of this reason was that the same enzyme immobilized on other membrane materials bearing hydrophilic character showed better performance. In this work, we provide direct evidence of the mechanism by immobilizing a PTE on a PVDF membrane hydrophilized by blending it with alkali lignin (AL). The PTE was immobilized on PVDF membrane by a covalent bond with the same procedure used in earlier studies to attribute changes in enzyme activity solely to the wettability properties (and not to the material chemistry). The activity of the PTE immobilized on the PVDF membrane hydrophilized with AL was 50% higher than that of the enzyme immobilized on the PVDF hydrophobic membrane. Further improvements of the membrane structure tailored for the development of a biocatalytic membrane reactor (BMR) were also promoted. In particular, the performance of the BMR was studied as a function of the thickness of the membrane, which allowed us to modulate the residence time into the enzyme-loaded membrane pores while maintaining the flow rate through the pores at a constant.

Formaldehyde-free biomass adhesive based on industrial alkali lignin with high strength and toughness

The preparation of industrial lignin-based adhesives generally requires the use of large amounts of petrochemical products or toxic and hazardous reagents, which severely limits their widespread application in the wood-based panel industry. In this study, we present a novel approach for synthesizing an eco-friendly lignin-based wood adhesive using aminated alkali lignin (AAL) and epoxy-terminated hyperbranched polyester (EHBP). The AAL was prepared by aminating alkali lignin through a green and formaldehyde-free method. The EHBP was synthesized by grafting epichlorohydrin onto biomass-derived hyperbranched polyester. The resulting adhesive performed excellent bonding strength of 2.41 MPa and debonding work of 0.711 J, which were 3.63 and 15.2 times higher than those of the pure lignin adhesive, respectively. This exceptional bonding strength surpassed that of most previously reported biomass adhesives. The moisture uptake value of the adhesive decreased by 75.6 % and the residual rate increased by 239.2 %. In addition, the prepared adhesive exhibited enhanced mold resistance. Importantly, the adhesive was primarily composed of biomass materials and their derivatives and was less costly than most commercial formaldehyde-based and bio-based adhesives. This work presents new possibilities for the high-value utilization of industrial lignin and the development of formaldehyde-free and environmentally friendly adhesives.

Improving Dispersion of Alkali Lignin in Natural Rubber by Adopting Graphene Oxide as a Carrier

Improving Dispersion of Alkali Lignin in Natural Rubber by Adopting Graphene Oxide as a Carrier