Lignin is the largest reservoir of aromatic compounds on earth and has great potential to be used in many industrial applications. Alternative methods to produce lignosulfonates from spent sulfite ...pulping liquors and kraft lignin from black liquor of kraft pulping process are critically reviewed herein. Furthermore, options to increase the sulfonate contents of lignin‐based products are outlined and the industrial attractiveness of them is evaluated. This evaluation includes sulfonation and sulfomethylation of lignin. To increase the sulfomethylation efficiency of lignin, various scenarios, including hydrolysis, oxidation, and hydroxymethylation, were compared. The application of sulfonated lignin‐based products is assessed and the impact of the properties of these products on the characteristics of their end‐use application is critically evaluated. Sulfonated lignin‐based products have been used as dispersants in cement admixtures and dye solutions more than other applications, and their molecular weight and degree of sulfonation were crucial in determining their efficiency. The use of lignin‐based sulfonated products in composites may result in an increase in the hydrophilicity of some composites, but the sulfonated products may need to be desulfonated with an alkali and/or oxygen prior to their use in composites. To be used as a flocculant, sulfonated lignin‐based products may need to be cross‐linked to increase their molecular weight. The challenges associated with the use of lignin‐based products in these applications are comprehensively discussed herein.
Tapping the aromatic source: The application of sulfonated lignin‐based products is assessed and the impact of the properties of these products on the characteristics of their end‐use application is critically evaluated. The challenges associated with the use of lignin‐based products in these applications are also comprehensively discussed.
Cationic kraft lignin (CKL) macromolecules were produced via polymerizing kraft lignin (KL) with 2-(acryloyloxy)ethyltrimethylammonium chloride (ATAC) or ...2-(methacryloyloxy)ethyltrimethylammonium methyl sulfate (METAM). Despite slightly different charge densities (2.3–2.5 mmol/g) of CKL, lignin–METAM (KL–METAM) had a significantly larger molecular weight and radius of gyration. A correlation was observed between the structure of CKLs and their impacts on the surface hydrophilicity of kaolin particles. In interacting with kaolin particles, KL–METAM generated larger and stronger flocs with looser structures than did KL–ATAC. Compared to ATAC, METAM had one additional methyl substituent on its structure, which provided fundamental evidence on how a small group (i.e., a methyl group) on the structure of a cationic monomer can have a substantial influence on its polymerization with lignin and subsequently on the efficiency of the induced macromolecule as a flocculant in a kaolin suspension system.
The morphological properties of nano cellulosic materials affect their industrial applications significantly. Solvents are commonly used in treating cellulosic materials in altered applications. In ...this work, the treatment of cellulose nanocrystals (CNCs) with dimethyl sulfoxide (DMSO) (99.5%) and N-methyl morpholine-N-oxide (NMMO) (50%) was investigated comprehensively under different conditions to evaluate the effect of solvent treatment on the properties of CNCs. A partial polymorphic transition of cellulose I to II was observed when CNCs were treated with the solvents. The temperature of the treatment was more influential than the time of the treatment in altering the CNC properties. XRD, light scattering, and wettability analyses confirmed that the partial dissolution of CNCs in solvents reordered the cellulosic chains from parallel to antiparallel. It also made more hydroxyl groups accessible on CNCs for hydrogen bonding, facilitating the CNC aggregation and instability in solutions. The XPS analysis revealed a remarkable alteration in the relative amounts of components in C 1s, reflecting transformation in the chemical bonds from C=O/O–C–O to C–O on the CNC surface. The increase in the hydroxyl group of CNCs also improved the water-uptake and hydrophilicity of CNCs when they were treated with solvents. The results of this work would suggest that the alteration in the CNC characteristics should be considered when selecting solvents for developing industrial applications for CNCs.
Lignin is one of the most abundant biopolymers on Earth and is considered as the primary resource of aromatic compounds. Recently, lignin has attracted attention from scientists and industrialists ...due to its inherent potential arising from its unique structure, which leads to its possible use in many applications. Many efforts have been made to ameliorate the reactivity and compatibility of lignin in different areas. Although methods have been proposed for endowing lignin with different properties, there continues to be a considerable demand for discovering new and effective ways of unraveling the beneficial uses of this aromatic polymer. Considering the structure of lignin, different grafting modifications can occur on the aliphatic and/or aromatic groups of lignin. To date, there has been a lack of fundamental understanding of the modification pathways of lignin for generating lignin-based products. In this review paper, we discuss comprehensively the chemical reactions that were introduced in the literature for preparing lignin with different features
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modifying its phenolic and aliphatic hydroxy groups for altered uses. This review paper critically and comprehensively elaborates on the recent progress in lignin reactions as well as the challenges, advantages and disadvantages associated with the reaction procedures and the product development processes. Furthermore, the research gap in reaction strategies and product development are described throughout this study.
In this work, various strategies for altering hydroxy group of lignin, the primary resource of aromatic compounds on earth, is discussed.
Currently, lignin of black liquor is incinerated to generate energy in pulp mills; but it has potential to be valorized through different modification methods. In this work, kraft lignin (KL) was ...polymerized with 2-(methacryloyloxy) ethyl trimethylammonium chloride (DMC) to produce cationic water soluble polymers. After producing five polymers with different molecular weights and charge densities, their flocculation efficiency in kaolin suspensions was investigated. The adsorption, zeta potential and flocculation results confirmed that the polymer with the highest charge density and molecular weight (KLD5) was a more effective flocculant than other polymers. The structure and size of flocs formed from the interaction of kaolin with KLD were determined by a focused beam reflectance measurement (FBRM). The sedimentation studies, conducted under gravitational (by vertical scan analyzer) and centrifugal force (by Lumisizer analytical centrifuge), revealed that KLD5 was very effective in flocculating kaolin particles.
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•Multifunctional lignin-based hybrid magnetic nanoparticles were synthesized.•The hybrid nanoparticles showed ultrafast adsorption capabilities for Pb2+ and Cu2+.•The abundant active ...sites from modified lignin enabled high efficiency of adsorption.•Adsorption was driven by ion exchange, hydrogen bonding and electrostatic attraction.
Heavy metals have raised an increasing number of pollution incidents and resulted in potent damages to aquatic ecosystems and human health. Thus, effective and efficient approaches to eliminate heavy metal ions are in urgent needs. Herein, novel hybrid nanoparticles have been prepared by a facile method using epichlorohydrin as a cross-linker between amino-functionalized magnetic nanoparticles and carboxymethylated lignin. Multiple characterization methods including XRD, FTIR, XPS, SEM, and TEM confirmed the formed nanostructures and the chemical features of the lignin-based hybrid nanoparticles. The as-synthesized hybrid nanoparticles exhibited high adsorption capacities of 150.33 and 70.69 mg/g for Pb2+ and Cu2+, respectively. More importantly, the adsorption equilibriums of Pb2+ and Cu2+ onto hybrid nanoparticles can be achieved within 30 s, which are among the fastest functional adsorbents for Pb2+ and Cu2+ removal as reported by now. The ultrafast adsorption is ascribed not only to the nanostructures, but also to the abundant active sites provided by the carboxymethylated lignin. The mechanism of removing Pb2+ and Cu2+ by hybrid nanoparticles could be mainly attributed to ion exchange and hydrogen bonding. The tailored nanostructured hybrid nanoparticles with exceptional adsorption effectiveness and efficiency are low-cost and eco-friendly, which potentially meets the cost-effective criteria for producing the water treatment adsorbents on a large scale.
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•The use of synthetic surfactants is reviewed in this work.•Anionic surfactants are the most widely used surfactants in industry.•The limitations and thus needs for use of bio-based ...surfactants are discussed.•Despite its use, lignosulfonate is not a very effective surfactant.•Recent progress in the production and use of lignin-based surfactants are reviewed.
Surface active agents (surfactants) are chemicals that can accumulate at the surface of a liquid, or interface between two phases with the role of changing the surface tension of the interface. Depending on their structures, they have many applications in industries, such as the petroleum, mining, pulping and textiles, wherein they are utilized as detergents, wetting agents, emulsifiers, foaming agents and dispersants. Most of commonly used surfactants are oil-based chemicals. However, using environmentally friendly feedstocks to produce surfactant is desirable to lessen the environmental impact of surfactant production and use in industry. Lignin is an attractive candidate for this purpose as it is inexpensive and readily available. Lignin and lignin derivatives, such as lignosulfonates, can be chemically modified to produce surfactants with different chemical and physical properties, which makes them suitable for a wide variety of applications. The lignin types and the processes performed for lignin production affect the properties of generated lignin significantly, which in turn influence the reactivity and the efficiency of the reaction for surfactant generation. In this review, the characteristics and applications of oil-based surfactants, and the efforts to produce lignin-based surfactants are reviewed. As oil-based surfactants with altered properties are available in the market, several different pathways can be followed for producing lignin-based surfactants. The advantages and disadvantages of using lignin-based surfactants are also discussed.
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•Kraft lignin was cationized with glycidyl-trimethylammonium chloride.•Reaction was optimized based on charge density and solubility of the product.•Cationic lignin was analyzed by ...FTIR, TGA, NMR, GPC and elemental analyzer.•Cationic lignin was used as a flocculant for dye removal from model wastewater.
The cationization of polymers was regarded as an effective method to improve their performance for various applications. In this work, the cationization of kraft lignin was investigated using glycidyl-trimethylammonium chloride (GTMAC) with kraft lignin in an aqueous solution under altered conditions. The conditions investigated were temperature, time, pH, GTMAC to lignin molar ratio, and lignin concentration. The optimized conditions based on charge density and solubility of cationic lignin were found to be 70°C, 1h, 12.5 pH, 2/1 GTMAC/lignin molar ratio, and 1.0wt.% lignin concentration. The solubility of the resulting cationic lignin reached 90% in 1wt.% lignin concentration and the charge density reached 1.10meq/g under the optimized conditions. The cationic lignin was characterized and compared with unmodified kraft lignin using elemental analysis, Fourier Transform Infrared (FTIR) spectrophotometer, proton nuclear magnetic resonance (1H NMR) and thermogravimetry (TGA) analysis in order to confirm the success of the grafting reaction. The cationic lignin was used as a flocculant for dye removal (Remazol Brilliant Violet, Reactive Black, and Direct Yellow) from model wastewater.
Kraft lignin is an abundant natural resource, but it is underutilized. In this study, sulfoalkylated lignin derivatives with similar charge densities but with different alkyl chain length were ...produced via sulfobutylation and sulfomethylation reactions. The contact angle studies revealed that sulfobutylated lignin (SBL) with longer alkyl chains had a higher hydrophobicity than sulfomethylated lignin (SML) did. The adsorption behavior of sulfoalkylated lignins was studied using a Quartz crystal microbalance with dissipation (QCM-D) on Al2O3 coated surface as representative of positively charged sites of kaolin particles. The results of adsorption studies showed that SBL deposited more greatly than SML did on the Al2O3 surface, and it generated a thicker but less viscoelastic adlayer on the surface. The adlayer thickness and configuration of molecules on the surface were also related to the zeta potential and stabilization performance of the polymers in the kaolin suspension system. The results also confirmed that both lignin derivatives were very effective in dispersing kaolin particles at neutral pH, and their effectiveness was hampered under alkaline or acidic pH.
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•Kraft lignin was carboxymethylated to produce a water soluble product.•Reaction was optimized based on charge density and solubility of the product.•Carboxymethylated lignin was ...analyzed by FTIR, TGA, GPC and elemental analyzer.•Carboxymethylated lignin was used as a dispersant for a clay suspension.
Kraft lignin is currently combusted in the pulping process to produce heat. It can be extracted from the process and converted to value-added products, but its limited water solubility hampers its end use applications. The main objective of this study was to investigate the carboxymethylation of hardwood kraft lignin to produce an anionic water soluble product. The results showed that the optimal conditions for carboxymethylation were 1.5M NaOH concentration, 3mol/mol sodium chloroacetate (SCA)/lignin ratio, 40°C, 4h and 16.7g/L lignin concentration. The produced lignin had a charge density and carboxylate group of 1.8meq/g and 1.68mmol/g, respectively. The carboxymethylated lignin was further characterized using thermogravimetric analyzer (TGA), Fourier Transform Infrared (FTIR) spectrophotometer, Nuclear magnetic resonance spectroscopy (H NMR) and elemental analyses. Moreover, the application of carboxymethylated lignin as a dispersant for a clay suspension was successfully analyzed by means of a photometric dispersion analyzer.
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