Lignin Amine Research Articles

One-pot amination and carboxylation functionalization of lignin for efficient adsorption of Cr(VI) and Cd(II): Influence of functional groups on adsorption equilibrium and mechanism

The removal of multiple heavy metal pollutants remains a challenge. Amination and carboxylation modified lignins (NCLs) prepared by one-pot hydrothermal method were used as adsorbents for Cr(VI) and Cd(II) removal. The oxygenous groups content in adsorbents was quantitatively analyzed by Boehm titration in which NCL10 (the mass ratio of citric acid: triethylene diamine = 10) possessed a maximum carboxyl group content of 1.22 mmol/g. The Langmuir adsorption isotherm model was the most suitable, with the highest theoretical adsorption capacity of Cr(VI) and Cd(II) of 1298.6 and 103.1 mg/g, respectively. Meanwhile, FT-IR and XPS exhibited that NCL5 surface contained many functional groups beneficial to the removal of Cr(VI) and Cd(II). The contribution of carboxyl and hydroxyl groups to the removal of Cr(VI) and Cd(II) was quantitatively analyzed. After the blocking of carboxyl and hydroxyl groups, the adsorption rate of Cr(VI) and Cd(II) decreased by 26.4 %, 67.7 % and 7.2 %, 43.3 %, respectively. This study provides effective strategies to overcome the limitations of lignin adsorbents for wastewaters containing a wide range of heavy metal pollutants.

Aqueous amine enables sustainable monosaccharide, monophenol, and pyridine base coproduction in lignocellulosic biorefineries

Thought-out utilization of entire lignocellulose is of great importance to achieving sustainable and cost-effective biorefineries. However, there is a trade-off between efficient carbohydrate utilization and lignin-to-chemical conversion yield. Here, we fractionate corn stover into a carbohydrate fraction with high enzymatic digestibility and reactive lignin with satisfactory catalytic depolymerization activity using a mild high-solid process with aqueous diethylamine (DEA). During the fractionation, in situ amination of lignin achieves extensive delignification, effective lignin stabilization, and dramatically reduced nonproductive adsorption of cellulase on the substrate. Furthermore, by designing a tandem fractionation-hydrogenolysis strategy, the dissolved lignin is depolymerized and aminated simultaneously to co-produce monophenolics and pyridine bases. The process represents the viable scheme of transforming real lignin into pyridine bases in high yield, resulting from the reactions between cleaved lignin side chains and amines. This work opens a promising approach to the efficient valorization of lignocellulose.

Phenolation, amination and cross-linking of lignin: synthesis and characterization of functionalized lignin

Phenolation, amination and cross-linking of lignin: synthesis and characterization of functionalized lignin

Solventless Amination of Lignin and Natural Phenolics using 2-Oxazolidinone.

Reactive amine compounds are critical for a vast array of useful chemicals in society, yet a limited number of them are derived from renewable resources. This study developed an efficient route to obtain aminated building blocks from phenolic resources derived from nature, such as lignin and tannic acid, for enhancing their utility in applications such as epoxy resins, nylons, polyurethanes, and other polymeric materials. The reaction utilized a carbon storage compound, 2-oxazolidinone as a solvent and as a reagent circumventing the need of hazardous chemistry of conventional amination routes such as those involving formaldehyde. Both free acids and hindered phenolics were readily converted into aminoethyl derivatives resulting in aromatics with primary amine functionality. The aminated compounds, with the potential for enhanced reactivity, can pave the way toward more advanced renewable building blocks.

Synthesis of polyurea nanocomposite from industrial waste lignin: Classical curing of isocyanate by lignin-polyamine

Polyurea is an important class of polymer obtained through curing of the isocyanate and polyamine. Here lignin amine processed successive three-step reactions for the synthesis of nanostructure polyurea composite. Further the competence nature is found out by combining different lignin-polyamine with various di-isocyanate. In the first step, lignin was reacted with tosyl-chloride which modified the hydroxy function of lignin as a good leaving group. This reaction for tosylated lignin (Lignin-OTs) has 80% yield. Further lignin-OTs was reacted with four different polyamines replaced tosyl functional group by amine gives aminated lignin. Eventually, a classical reaction of aminated lignin and three different di-isocyanate yield a polyurea composite. A series of changes from lignin to its tosylation eventually to polyurea composite was pursued by the change in the functional group of lignin. The tosylated lignin was confirmed by IR absorption of the C-O peak at 1190 and 1365 cm−1 and invisible peak absorption at 3500 cm−1. The aminated lignin was confirmed by IR absorption at 3120 and 3430 cm−1 for –NH. Thermal gravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to determine the product's thermal characteristics. Complete structural morphology of nanostructure lignin-polyurea composite was investigated by X-ray diffraction, FE-SEM and EDX.

A Mechanistic Study of HZSM-5-Catalyzed Guaiacol Amination Using Photoionization Time-of-Flight Mass Spectrometry

Thermal-catalytic conversion and amination (TCC-A) of lignin and lignin derivates over zeolites is a promising and renewable method to produce aromatic amines, but suffers from product diversity. Currently, no unambiguous mechanism could fully describe the chemistry of this process. In this work, the TCC-A mechanism of guaiacol, a typical lignin model compound, with ammonia over HZSM-5 was investigated by online photoionization time-of-flight mass spectrometry combined with density functional theory. Various products including amines, pyrroles, and pyridines were identified. The formation of methylamine and aminophenol below 400 °C via nucleophilic substitutions is attributed to the strong adsorption of ammonia on the active site of HZSM-5. Aniline is the major product above 400 °C coproduced with pyrroles and pyridines. It is suggested that the reactions among radical intermediates (•CH3 and •NH2) and molecules (guaiacol and catechol) lead to poor aniline selectivity via transmethylation, amination, and partial deoxygenation reactions. Hydroamination is proposed as the main formation mechanism of pyrroles and pyridines. The maximum yield of aniline can be achieved at 650 °C owing to the enhancement of amination and deoxygenation and the suppression of transmethylation reactions.

Boosting Surface‐Dominated Sodium Storage of Carbon Anode Enabled by Coupling Graphene Nanodomains, Nitrogen‐Doping, and Nanoarchitecture Engineering

AbstractThe development of high‐performance carbon anode for sodium‐ion batteries is limited by the sluggish kinetics and structural instability. Expanded interlayer spacing, nitrogen doping, and mesoporous structure engineering have emerged as promising strategies to overcome these challenges. Simultaneously achieving graphene nanodomains construction, high‐efficient nitrogen doping, and rational mesoporous structure engineering is challenging. Herein, a strategy of pyrolyzing SiO2@ lignin amine urea‐formaldehyde resin is proposed for deliberate manipulation of graphene nanodomains, edge‐nitrogen doping, and specific mesoporous distribution in amorphous lignin‐derived carbon based on polycondensation‐template. The obtained carbon material exhibits a nitrogen‐doping level of 6.03 at% with a high edge‐nitrogen ratio of up to 84.4%, high‐ connectivity mesoporous structure, and graphene nanodomains with expanded interlayer spacing. The optimized carbon material delivers a reversible capacity of 234 mAh g−1 at 100 mA g−1, superior rate capability of 129 mAh g−1 at 2 A g−1, and excellent cycling stability. In addition, the surface‐dominated sodium‐ion storage mechanism is identified by in situ electrochemical impedance spectroscopy. Furthermore, the optimized carbon can function as an outstanding anode for full cells. This work proposes a new avenue for designing high‐performance carbon for low‐cost and high‐rate sodium‐ion batteries.

Integrated design of an amination process of lignin oxygenated model compounds to synthesize cyclohexylamine: catalyst nanostructure engineering and catalytic conditional strategy

This review summarizes the research progress in the one-pot catalytic amination of lignin oxygenated model compounds to cyclohexylamine, specifically from the catalyst nanostructure engineering and catalytic conditional strategy.

Green and facile synthesis of aminated lignin-silver complex and its antibacterial activity

Silver nanoparticles (AgNPs) exhibit broad spectrum antibacterial effect, but their cores after use can persist in the environment, which presents a toxic effect on humans. To address this issue, silver-based biomaterials are regarded as green alternatives to AgNPs. In this study, we used kraft lignin, a green and biodegradable polymer derived from wood biomass, to prepare an aminated lignin-silver complex (Ag@AL complex) as an alternative antibacterial agent. A facile approach for preparing aminated lignin (AL) was realized by the amination of kraft lignin using 2-chloroethylamine hydrochloride in water solvent. The nitrogen content of optimized AL was 4.37 %. Ag(Ⅰ) could be captured and reduced to metallic Ag(0) by AL, thereby forming AgNPs on the surface of AL. Importantly, the obtained Ag@AL complex was proven to be an effective antibacterial agent against gram-positive (Bacillus cereus, Staphylococcus aureus) and gram-negative (Salmonella enterica) bacteria.

The influence of amination of sorbent based on buckwheat (Fagopyrum esculentum) husks on the sorption effectiveness of Reactive Black 5 dye

Buckwheat husks (Fagopyrum esculentum) modified with epichlorohydrin (ECH) and ammonia water (NH3*H2O) were tested as potential sorbent for Reactive Black 5 (RB5) dye. FTIR and pHPZC measurements were used to characterize sorbents. The influence of pH, contact time and concentration of the dye on RB5 sorption has been investigated. The FTIR spectra analysis confirmed the amination of polysaccharides and lignin in buckwheat husks modified with ammonia water. The effectiveness of RB5 sorption was the highest at pH 3. The sorption equilibrium time was from 240 to 300 min. Equilibrium data were well fitted to the Double Langmuir adsorption model. The maximum RB5 sorption capacity of modified buckwheat husks was Qmax = 85.18 mg/g, which was over 19 times higher than that of unmodified buckwheat husks (Qmax = 4.43 mg/g).

Hydrogenation of α-Pinene Catalyzed by Ru Nanoparticles Stabilized by Magnetic Alkali Lignin Amine

Hydrogenation of α-Pinene Catalyzed by Ru Nanoparticles Stabilized by Magnetic Alkali Lignin Amine

One-step silanization and amination of lignin and its adsorption of Congo red and Cu(II) ions in aqueous solution

In this work, silanized and aminated lignin (SAL) was synthesized in one step and its adsorption of Congo red and Cu(II) ions in aqueous solution was explored. Lignin was subjected to amine-silanization with (3-aminopropyl) triethoxysilane (APTES). Structural characterization substantiated successful amine-silanzation of lignin and formation of multi-layer APTES intermolecular crosslinked structure. The prepared SAL (nitrogen content = 6.1%) exhibited enhanced molecular weight, thermal stability, and water- and organic solvent-resistance properties. Additionally, the present of the porous structure of particle surface and an increase in the specific surface area and zeta potential promoted the accessibility of contaminants to the effective adsorption sites of SAL. Adsorption experiments showed that both Congo red and Cu(II) ion could be completely removed at original pH value, and their adsorption involved electrostatic attraction and complexation, respectively. The adsorption isotherms and kinetics were well described by the Langmuir and pseudo-second-order equations, respectively. The results showed that SAL is a promising adsorbent for the treatment of effluents.

Fabrication of dually N/S-doped carbon from biomass lignin: Porous architecture and high-rate performance as supercapacitor

The lignin amine (LA) was exploited to prepare dually N/S-doped carbon (NSC), which was endowed with intriguing porous structure by Fe3O4 template. N and S elements, originating from LA, are doped into the materials. NSC possesses diverse-scale 3D pores. The macropores are made by Fe3O4, which facilitate to produce meso and micro pores on their walls by KOH activation. The sample prepared at 700 °C (NSC-700) is found to have the largest specific surface area (1199 cm2 g−1) and specific capacity (241 F g−1 at current density of 1 A g−1). Its capacity is 260% as high as that of lignin amine carbon (LAC) prepared without adding Fe3O4. Excellent rate performance is unraveled because of possessing 82% specific capacity at 20 A g−1 and 27.2 Wh kg−1 energy density at 10000 W kg−1 power density. Moreover, the specific capacity maintains 95.0% after 3000 cycles, indicating good electrochemical stability. The good electrical performance of NSC-700 is attributed to its interesting electronic properties that are induced by special pore structure. Because of having merits such as high rate performance, long life, large specific capacity and low cost, our NSC is anticipated to be a promising capacitor as electrode material.

An Experimental Approach to Formulate Lignin-Based Surfactant for Enhanced Oil Recovery

The higher cost of chemical surfactants has been one of the main reasons for their limited used in enhanced oil recovery (EOR) process. Hence, the reason for developing lignin-based surfactant is to lower the cost of chemicals as it does not tie to the price of crude oil as compared to petroleum-based surfactants. Besides, lignin is biodegradable and easily extracted from plant waste. The objectives of this study are to determine the formulations of the lignin-based surfactant for EOR applications and to determine the oil recovery performance of the formulated surfactants through surfactant flooding. The lignin-based surfactants were formulated by mixing the lignin with the amine (polyacrylamide or hexamethylenetetramine) and the surfactant sodium dodecylbenzenesulfonate in a 20,000 ppm NaCl brine. Interfacial tension (IFT) of the formulated lignin-based surfactant is measured at ambient temperature using the spinning drop method. The displacement experiments were conducted at room temperature in glass beads pack holders filled with glass beads, saturated with paraffin and brine. The results of the study showed that the best formulation of lignin-based surfactant is using hexamethylenetetramine as the amine, lignin, and sodium dodecylbenzenesulfonate at 2% total active concentration. The oil recovery and interfacial tension using the lignin amine system is comparable with the commercial petroleum sulfonate system.

In situ reduction of silver nanoparticles in the lignin based hydrogel for enhanced antibacterial application.

Although antibiotics have been widely used, the problem of bacterial infection in the medical field still faces many challenges. In this study, we designed a new lignin based antimicrobial hydrogel for antimicrobial application. First, we grafted the amino group onto sodium lignin sulfonate through Mannich reaction to obtain lignin amine (LA), which can cross-link with poly(vinyl alcohol) (PVA) to form hydrogel. Then, silver nitrate solution is added to the formed gel pre-solution to be in situ reduced to silver nanoparticles. The enhanced effect of antibacterial properties due to lignin and silver nanoparticles endows the hydrogel enhanced antibacterial properties. The modification of sodium lignosulfonate and the crosslinking reaction between LA and PVA are confirmed by FTIR, while the content of nitrogen in LA is characterized by XPS. The SEM image of the hydrogel after lyophilization illustrates its internal porous network structure. The rheological test of hydrogel demonstrates its good strength and elasticity. The hydrogel exhibits good antibacterial properties in in vitro antibacterial experiments towards both S. aureus and E. coli, while toxicity tests using L929 cells demonstrated good biocompatibility of the hydrogel.

Amination of biorefinery technical lignin by Mannich reaction for preparing highly efficient nitrogen fertilizer.

To develop a novel lignin-based highly efficient nitrogen fertilizer, the amination of the biorefinery technical lignin was conducted by Mannich reaction synergy with phenolation pretreatment. Subsequently, the structural transformations of lignin samples and the reaction mechanism were investigated in detail. The soil column leaching experiment was also performed to research the nitrogen release behavior of aminated lignin in soil. The results indicated that the amounts of active sites in lignin were significantly increased to 8.26 mmol/g from the original 2.91 mmol/g by phenolation. In addition, the Mannich reaction was highly selective for occurring at ortho- and para-positions of phenolic hydroxyl groups in the phenolated lignin, in which the latter was favored. Moreover, the nitrogen content in the aminated lignin was highly depended on the types of amination reagent instead of the proportion of reactants in this study. Under an optimal condition, aminated lignin with a high nitrogen content (10.13%) and low C/N ratio (6.08) could be obtained. Besides, it was especially noteworthy that the prepared APL in this study has a favorable nitrogen release behavior in soil. Thus, it is believed that these aminated lignin derivatives could be used for the preparation of various lignin-based highly efficient nitrogen fertilizer.

Dual effect of lignin amine on fabrication of magnetic Fe3O4/C/ZnO nanocomposite in situ and photocatalytic property

The Fe3O4/C/ZnO ternary composite has been synthesized by a facile one-pot method, in which lignin amine (LA) was used as carbon source as well as bridging ligand. Its structure, morphology and composition have been intensively characterized. The composite is found to be composed by cubic spinel Fe3O4, amorphous carbon and hexagonal wurtzite ZnO. Its morphology features as particles in the mean sizes of about 20 nm, which is larger than those of Fe3O4 and Fe3O4/ZnO. This case may be caused by the special construction of the resulting composite. Fe3O4 is covered by carbon, together forming particles; simultaneously, they interconnect with ZnO particles, leading to an increase in the particle size. With these peculiar structural characteristics, the synergistic effect is unraveled to enhance catalytic property of the composite while being applied in water treatment. Fe3O4/C/ZnO under both ultraviolet and visible light irradiation is found to show high degradation efficiencies. More importantly, the catalytic performance is very stable, maintaining 94% even after 5-cycle re-using test. Moreover, our composite materials also display excellent photocatalytic activities on degrading norfloxacin (NF) that is widely used as antibody. Due to easy recovery, good performance and facile synthetic route, our Fe3O4/C/ZnO is anticipated to have a good practical prospect in applications of water treatment.

One-Step Fabrication of Dual Responsive Lignin Coated Fe3O4 Nanoparticles for Efficient Removal of Cationic and Anionic Dyes

A new, simple one-step approach has been developed to synthesize lignin and lignin amine coated Fe3O4 nanoparticles. These nanoparticles (lignin magnetic nanoparticles (LMNPs) and lignin amine magnetic nanoparticles (LAMNPs)) are found to possess not only magnetic response but also pH-dependent adsorption behavior. Results show that the combination of lignin with nanoparticles increased the adsorption capacities 2–5 times higher than other traditional single lignin based adsorbents (211.42 mg/g for methylene blue (MB) by LMNPs and 176.49 mg/g for acid scarlet GR (AS-GR) by LAMNPs). Meanwhile, by simply adjusting the pH, the dye-loaded adsorbents can be regenerated to recycle both adsorbents and dyes with a desorption efficiency up to 90%. Mechanistic study shows that dye structure and surface charges of adsorbents play the most important part in adsorption where dyes interact with the adsorbent surface via π–π stacking and electrostatic attraction interactions. The efficient fabrication method, eco-friendly reactant, quick magnetic separation, high adsorption and desorption efficiency suggest this novel type of nano-adsorbents to be promising materials for efficient dye pollutant removal and recovery.

Preparation and Properties of Hydrogels Based on PEGylated Lignosulfonate Amine.

Sodium lignosulfonate (SLS) was aminated to obtain a lignin amine (LA) compound, which was subsequently crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE) to obtain hydrogels. The chemical structure of the resulting LA-derived hydrogel (LAH) was characterized by Fourier transform infrared (FTIR) spectroscopy, solid-state 13C NMR spectroscopy, and elemental analysis, and the interior morphology of the freeze-dried hydrogel was examined by scanning electron microscopy. NMR and FTIR spectroscopy results indicated that the amino groups of LA reacted with PEGDGE in the crosslinking reaction. The lignin content in the resulting hydrogel increased with an increase in the LA/PEGDGE weight ratio in the reaction, approaching a maximum (∼71 wt %) and leveling off. The hydrogel with such a composition happened to be the same as the one prepared by reacting the primary amines of LA and epoxy groups of PEGDGE in equal stoichiometry. These results strongly suggest that the formation of the hydrogel network structure was largely dictated by the reactions between the primary amines and epoxy groups. The gels with lignin contents at this level exhibited a superior swelling capacity, viscoelasticity, and shear properties.

A Novel and Formaldehyde-Free Preparation Method for Lignin Amine and Its Enhancement for Soy Protein Adhesive

In this work, a novel two-step process to prepare primary lignin amine was developed. The lignin used in this study was obtained from the residue of cellulosic sugar fermentation for bioethanol (referred as “lignin”). The lignin was initially oxidized through Fenton oxidation. The oxidized lignin was further converted to lignin amine by reductive amination. Ammonia was used in the second step leading to give the highly active primary lignin amine. The oxidation and reduction exhibited relatively high yields of 80.0 and 91.2 % respectively. For comparison, lignin was partially depolymerized via mild hydrogenolysis and then the partial depolymerized lignin was also converted to lignin amine using the same method. The obtained lignin amines were characterized in detail using elemental analysis, proton nuclear magnetic resonance (1H NMR), and Fourier transform infrared spectroscopy (FTIR). Further, modification of soy protein adhesive by lignin amine was exemplified in wood bonding, and the results indicated that addition of lignin amine greatly increased water resistance of soy protein adhesives.