Fabrication of a green porous lignin-based sphere for the removal of lead ions from aqueous media

High adsorption capacities for dyes by a pH-responsive sodium alginate/sodium lignosulfonate/carboxylated chitosan/polyethyleneimine adsorbent

Dyes are indispensable for the rapid development of society, but untreated dye wastewater can threaten human health. In this study, an adsorbent (SA/SL/CCS/PEI@MNPs) was synthesized by one-pot method using magnetic nanoparticles (MNPs), sodium alginate (SA), sodium lignosulfonate (SL), carboxylated chitosan (CCS) and polyethyleneimine (PEI). The adsorbent was mesoporous micrometer-sized particles with pore size of 34.92 nm, which was favorable for dynamic column experiments. SA/SL/CCS/PEI@MNPs possessed pH-responsive performance. Under acidic condition, the maximum adsorption capacities for anionic dyes (tartrazine, reactive black-5, indigo carmine) reached >550 mg/g. Under alkaline condition, those for cationic dyes (methylene blue, methyl violet, neutral red) exceeded 1900 mg/g. The function of the various modifiers was investigated. The results indicated that the incorporation of SL, CCS and PEI was able to provide plenty of sulfonate, carboxylate and amino/imine reactive groups so that adsorption capacities of dyes were improved. The adsorption mechanism was explored by FTIR and XPS. At the same time, the adsorption mechanism was more deeply analyzed using molecular dynamics simulations and radial distribution function. It was demonstrated that the dyes adsorption on the SA/SL/CCS/PEI@MNPs was mainly due to electrostatic attraction and π-π interaction. In addition, the adsorbent had good reusability, and the removal still reached over 90 % after five cycles. In conclusion, the adsorbent displayed a broad prospect for the adsorption of organic dyes.

Unlocking the potential: Evolving role of technical lignin in diverse applications and overcoming challenges

Recent advancements have transformed lignin from a byproduct into a valuable raw material for polymers, dyes, adhesives, and fertilizers. However, its structural heterogeneity, variable reactive group content, impurities, and high extraction costs pose challenges to industrial-scale adoption. Efficient separation technologies and selective bond cleavage are crucial. Advanced pretreatment methods have enhanced lignin purity and reduced contamination, while novel catalytic techniques have improved depolymerization efficiency and selectivity. This review compares catalytic depolymerization methodologies, highlighting their advantages and disadvantages, and noting challenges in comparing yield values due to variations in isolation methods and lignin sources. Recognizing "technical lignin" from pulping processes, the review emphasizes its diverse applications and the necessity of understanding its structural characteristics. Emerging trends focus on bio-based functional additives and nanostructured lignin materials, promising enhanced properties and functionalities. Innovations open possibilities in sustainable agriculture, high-performance foams and composites, and advanced medical applications like drug delivery and wound healing. Leveraging lignin's biocompatibility, abundance, and potential for high-value applications, it can significantly contribute to sustainable material development across various industries. Continuous research in bio-based additives and nanostructured materials underscores lignin's potential to revolutionize material science and promote environmentally friendly industrial applications.

Synthesis of high-performance antibacterial agent based on incorporated vancomycin into MOF-modified lignin nanocomposites

The alarming rise in antibiotic resistance necessitates urgent action, particularly against the backdrop of resistant bacteria evolving to render conventional antibiotics less effective, leading to an increase in morbidity, mortality, and healthcare costs. Vancomycin-loaded Metal-Organic Framework (MOF) nanocomposites have emerged as a promising strategy in enhancing the eradication of pathogenic bacteria. This study introduces lignin as a novel synergistic agent in Vancomycin-loaded MOF (Lig-Van-MOF), which substantially enhances the antibacterial activity against drug-resistant bacteria. Lig-Van-MOF exhibits six-fold lower minimum inhibitory concentration (MICs) than free vancomycin and Van-MOF with a much higher antibacterial potential against sensitive and resistant strains of Staphylococcus aureus and Escherichia coli. Remarkably, it reduces biofilms of these strains by over 85 % in minimal biofilm inhibitory concentration (MBIC). Utilization of lignin to modify surface properties of MOFs improves their adhesion to bacterial membranes and boosts the local concentration of Reactive Oxygen Species (ROS) via unique synergistic mechanism. Additionally, lignin induces substantial cell deformation in treated bacterial cells. It confirms the superior bactericidal properties of Lig-Van-MOF against Staphylococcus species, underlining its significant potential as a bionanomaterial designed to combat antibiotic resistance effectively. This research paves the way for novel antibacterial platforms that optimize cost-efficiency and broaden microbial resistance management applications.

Bio-derived carbon-based materials for sustainable environmental remediation and wastewater treatment

Biosynthesized nanocomposites, particularly those incorporating carbon-based materials, exhibit exceptional tunability and multifunctionality, surpassing the capabilities of conventional materials in these aspects. Developing practical solutions is critical to address environmental toxins from pharmaceuticals, heavy metals, pesticides, and dyes. Biomass waste is a readily available carbon source, which emerges as a promising material for producing biochar due to its inherent advantages: abundance, low cost, and environmentally friendly nature. This distribution mainly uses carbon-based materials (CBMs) and biomass waste in wastewater treatment. This review paper investigates several CBM types, including carbon aerogels, nanotubes, graphene, and activated carbon. The development of bio-derived carbon-based nanomaterials are discussed, along with the properties and composition of carbon materials derived from biomass waste and various cycles, such as photodegradation, adsorption, and high-level oxidation processes for natural remediation. In conclusion, this review examines the challenges associated with biochar utilization, including cost, recovery, and practical implementation.

Green synthesized lignin nanoparticles for the sustainable delivery of pyraclostrobin to control strawberry diseases caused by Botrytis cinerea

Lignin, renowned for its renewable, biocompatible, and environmentally benign characteristics, holds immense potential as a sustainable feedstock for agrochemical formulations. In this study, raw dealkaline lignin (DAL) underwent a purification process involving two sequential solvent extractions. Subsequently, an enzyme-responsive nanodelivery system (Pyr@DAL-NPs), was fabricated through the solvent self-assembly method, with pyraclostrobin (Pyr) loaded into lignin nanoparticles. The Pyr@DAL-NPs shown an average particle size of 250.4 nm, demonstrating a remarkable loading capacity of up to 54.70 % and an encapsulation efficiency of 86.15 %. Notably, in the presence of cellulase and pectinase at a concentration of 2 mg/mL, the release of Pyr from the Pyr@DAL-NPs reached 92.66 % within 120 h. Furthermore, the photostability of Pyr@DAL-NPs was significantly improved, revealing a 2.92-fold enhancement compared to the commercially available fungicide suspension (Pyr SC). Bioassay results exhibited that the Pyr@DAL-NPs revealed superior fungicidal activity against Botrytis cinerea over Pyr SC, with an EC50 value of 0.951 mg/L. Additionally, biosafety assessments indicated that the Pyr@DAL-NPs effectively declined the acute toxicity of Pyr towards zebrafish and posed no negative effects on the healthy growth of strawberry plants. In conclusion, this study presents a viable and promising strategy for developing environmentally friendly controlled-release systems for pesticides, offering the unique properties of lignin.

Preparation, characterization, and adsorption performance of porous polyamine lignin microsphere

In this study, a porous polyamine lignin microsphere (PPALM) was prepared through the inverse suspension polymerization combined with freeze-drying, during which sodium lignosulfonate and polyetheramine (PEA) were crosslinked with epichlorohydrin (ECH) as the cross-linker. By adjusting the amount of ECH and PEA, the optimized PPALM exhibited suitable crosslinking degree, ensuring a balance of framework flexibility and rigidity, thereby facilitating the formation of abundant and fine pores. PPALM demonstrated good mechanical properties comparable to commercial sulfonated polystyrene cationic resin, with a porosity of 61.12 % and an average pore size of 283.51 nm. The saturation adsorption capacity of PPALM for Pb2+ was measured to be 156.82 mg/g, and it remained above 120 mg/g after five cycles of regeneration. Particularly, the concentration of 50 mg/L Pb2+ solution could be reduced to 0.98 mg/L after flowing through the PPALM packed bed, indicating the great potential of PPALM for application in wastewater treatment.

Full biomass-based multifunctional flocculant from lignin and cationic starch

Flocculation is a common process for wastewater treatment. However, the most commonly used organic synthetic flocculants such as polyacrylamide are petroleum-based. In this work, biomass lignin was grafted with cationic starch to synthesize low-cost, green and fully biomass-based multifunctional flocculants. The cationic polyacrylamide was replaced by cheap industrial cationic starch. Hyperbranched multifunctional lignin-grafted cationic starch flocculant (CS-L) was successfully prepared via ring-opening reaction with epichlorohydrin. The mass content of lignin in the grafted product was between 16.6 % and 70.1 %. With the dosage of CS-L between 4.0 and 7.5 mg/l, the turbidity removal rate for 500 mg/l kaolin suspension reached more than 97 %. When the dosage of CS-L was 24 mg/l, the removal rate of 50 mg/l Cu2+ reached 85.7 %. Importantly, when the mixed solution of kaolin particles and Cu2+ was treated, the synchronous removal rates of kaolin and Cu2+ reached 90 % and 72 % respectively in the range of 8.0-12.0 mg/l flocculant addition. The synthesized lignin-grafted cationic starch flocculant showed an excellent multifunctional flocculation function.

Health effects of herbicides and its current removal strategies

The continually expanding global population has necessitated increased food supply production. Thus, agricultural intensification has been required to keep up with food supply demand, resulting in a sharp rise in pesticide use. The pesticide aids in the prevention of potential losses caused by pests, plant pathogens, and weeds, but excessive use over time has accumulated its occurrence in the environment and subsequently rendered it one of the emerging contaminants of concern. This review highlights the sources and classification of herbicides and their fate in the environment, with a special focus on the effects on human health and methods to remove herbicides. The human health impacts discussion was in relation to toxic effects, cell disruption, carcinogenic impacts, negative fertility effects, and neurological impacts. The removal treatments described herein include physicochemical, biological, and chemical treatment approaches, and advanced oxidation processes (AOPs). Also, alternative, green, and sustainable treatment options were discussed to shed insight into effective treatment technologies for herbicides. To conclude, this review serves as a stepping stone to a better environment with herbicides.

Alginate/geopolymer hybrid beads as an innovative adsorbent applied to the removal of 5-fluorouracil from contaminated environmental water

Water contaminated by cytostatic drugs has many negative impacts on the ecosystems. In this work, cross-linked adsorbent beads based on alginate and a geopolymer (prepared from an illito-kaolinitic clay) were developed for a promising decontamination of the 5-fluorouracil (5-FU) cytostatic drug from water samples. The characterization of the prepared geopolymer and its hybrid derivative was performed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and termogravimetric analysis. Batch adsorption experiments indicated that alginate/geopolymer hybrid beads (AGHB) allow an excellent 5-FU removal efficiency of up to 80% for a dosage adsorbent/water of 0.002 g/mL and a concentration of 5-FU of 2.5 mg/L. The adsorption isotherms data follow well the Langmuir model. The kinetics data favor the pseudo-second-order model. The maximum adsorption capacity (q_max) was 6.2 mg/g. The optimal adsorption pH was 4. Besides pore filling sorption process, the carboxyl and hydroxyl groups from alginate immobilized onto the geopolymer matrix favored the retention of 5-FU ions by hydrogen bonds. Common competitors, such as dissolved organic matter, do not significantly affected the adsorption. In addition, this material has not only eco-friendly and cost-effective advantages but also excellent efficiency when applied to real environmental samples such as wastewater and surface water. This fact suggests that it could have a great application in the purification of contaminated water.

Electrospray lignin nanoparticles as Pickering emulsions stabilizers with antioxidant activity, UV barrier properties and biological safety

The inherent complexity and large particle size of native-state lignin are the major factors limiting its performance in high value-added materials. To realize the high-value application of lignin, nanotechnology is a promising method. Therefore, we offer a nanomanufacturing approach to produce lignin nanoparticles with uniform size, regular shape and high yield using electrospray. They are efficient in stabilizing oil-in-water (O/W) Pickering emulsions that remain for one month. Lignin has the abilities to demonstrate broad-spectrum UV resistance and green antioxidant properties in advanced materials, taking advantage of its inherent chemical characteristics. In addition, lignin has high safety for topical products according to an in vitro cytotoxicity test. In addition, the nanoparticle concentrations used in the emulsion were as low as 0.1 mg/ml, which maintained UV-resistant ability and overcame traditional lignin-based materials with unfavorable dark colors. Overall, lignin nanoparticles not only act as stabilizers at the water-oil interface but also realize the high functionality of lignin.

Enhanced removal of hexavalent chromium by lignosulfonate modified zero valent iron: Reaction kinetic, performance and mechanism

The application of lignin derivative as modifier is an economical and efficient approach to improve the reactivity of raw material towards pollutant removal. In this study, lignosulfonate modified zero valent iron (LS-ZVI) was firstly prepared by ball-milling method and utilized for Cr(VI) removal under different conditions. The comparative experiments showed that lignosulfonate modification could significantly enhance the Cr(VI) removal by ZVI from <10 % to 100 % within 90 min reaction. Compared to ZVI, the specific surface area of LS-ZVI increased 3.4 times and surface Fe(0) content increased from 3.4 % to 10.5 % due to the surface erosion, resulting in the high-efficient Cr(VI) removal. Solution and solid-phase analyses indicated that Fe(0) played dominated role and generated Fe(II) involved in Cr(VI) removal process, which mainly included rapid adsorption, reduction and co-precipitation. Batch experiments revealed that lower pH conditions were beneficial for Cr(VI) removal and the effect of co-existing ions (Ca²⁺, Mg²⁺, NO₃^-, Cl^-, and SO₄^2-) was negligible except the inhibitory effect of NO₃^-. Moreover, LS-ZVI also exhibited excellent removal performance for Ni(II), Zn(II), and Cd(II) with removal efficiency beyond 96.6 %. Overall, this work provides a feasible approach for enhancing the reactivity of commercial ZVI in the treatment of heavy metal pollution.

Lignin nanoparticles-reduced graphene oxide based hydrogel: A novel strategy for environmental applications

In this work, facile fabrication of lignin nanoparticles (L_NP)-based three-dimensional reduced graphene oxide hydrogel (rGO@L_NP) has been demonstrated as a novel strategy for environmental applications. Herein, L_NP were facilely synthesized from walnut shell waste through a direct chemical route. These L_NP were incorporated into the continuous porous network of rGO network to fabricate rGO@L_NP hydrogel. Characterization studies were carried out using various analytical techniques viz. scanning electron microscopy, Fourier transform IR spectroscopy, X-ray diffraction and thermogravimetric analysis. The efficiency of rGO@L_NP hydrogel as adsorptive platform was evaluated by employing methylene blue and Pb²⁺ as model pollutants, whilst the effect of various experimental parameters was ascertained for optimal performance. Furthermore, Agar well diffusion method was used to check the antibacterial activities of the hydrogel using two bacterial pathogenic strains, i.e. Klebsiella pneumoniae (gram negative) and Enterococcus faecalis (gram positive). Results showed that after the inclusion of L_NP into rGO hydrogel, there was a marked improvement in pollutant's uptake ability and compared to bare L_NP and rGO, the composite hydrogel showed enhanced bactericidal effect. Overall, this approach is outstanding because of the synergy of functional properties of nano-lignin and rGO due to multi-interaction sites in the resulting hydrogel. The results presented herein support the application of rGO@L_NP as innovative water filter material for scavenging broad spectrum pollutants and bactericidal properties.

Lignin as a bioactive polymer and heavy metal absorber- an overview

As a pulping and bio-refinery by-product with phenolic chemical structure, lignin indicated high potential as natural antioxidant activity, UV blocker, antibacterial and toxic material absorbent properties. Presence of phenolic hydroxyl groups in lignin structure plays the main role of its antioxidant activity. However, lignin antioxidant power can change depending on its other structural features and functional groups like ortho-methoxy groups, -OCH₃ groups, the α-CH₂ groups, the aliphatic carbonyl groups, and the size of π-conjugated systems. Lignin in mixture with synthetic polymers, improved their thermal stability. Lignin has high UV light absorbing potential in broad-spectrum (UVA, UVB). Adding 1-5% of lignin into hand cream indicated excellent range of sun protection factor (SPF) with more than 95% UV light absorption. Lignin also indicated strong UV light protection when applied in different transparent film and protect paint, oil, and varnish from UV degradation. Lignosulfonate and other modified lignin including chemically modification, nano-particles and lignin hydrogel indicated high potential as heavy metal absorber.

From residue to resource: new insights into the synthesis of functionalized lignin micro/nanospheres by self-assembly technology for waste resource utilization

Among the most abundant biopolymers in the biosphere, lignin is a renewable aromatic compound that represents an untapped opportunity to create new biological products. However, the complex interlacing structures of cellulose, hemicellulose and lignin, as well as the unique properties of lignin, limit the utilization of value-added lignin. Lignin-based nanomaterials open the door for lignin applications in environmental pollutant remediation, biofuel production, biomedicine, and other fields. Herein, we present various factors influencing the formation of micro-nanospheres by self-assembly techniques through a review of previous literature, and emphasize the simple and green synthesis of lignin micro/nanospheres (LMNPs) under non-modified conditions. More importantly, we discuss the mechanism of the formation of nanospheres. Considering the heterogeneity of lignin and the polarity of different solvents, we propose that self-assembly techniques should focus more on the influence brought by lignin itself or the solvent, so that the external conditions can be controlled to prepare LMNPs, which can be used in specific fields. A brief overview of the contribution of lignin-based nanomaterials in various fields is also presented. This review could provide insight for the development of lignin-based nanomaterials.

Lignin Nanoparticles and Alginate Gel Beads: Preparation, Characterization and Removal of Methylene Blue

A novel and effective green system consisting of deep eutectic solvent (DES) was proposed to prepare lignin nanoparticles (LNPs) without any lignin modification. The LNPs are obtained through the dialysis of the kraft lignin-DES solution. The particle size distribution, Zeta potential and morphology of the LNPs are characterized by using dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average diameter of LNPs is in the range 123.6 to 140.7 nm, and the LNPs show good stability and dispersibility in water. The composite beads composed of LNPs and sodium alginate (SA) are highly efficient (97.1%) at removing methylene blue (MB) from the aqueous solution compared to 82.9% and 77.4% by the SA/bulk kraft lignin composite and pure SA, respectively. Overall, the LNPs-SA bio-nanocomposite with high adsorption capacity (258.5 mg/g) could be useful in improving water quality and other related applications.

Carbohydrate biopolymers, lignin based adsorbents for removal of heavy metals (Cd2+, Pb2+, Zn2+) from wastewater, regeneration and reuse for spent adsorbents including latent fingerprint detection: A review

Living organisms are created by carbohydrate biopolymers such as chitosan, carboxymethyl cellulose, alginate and lignin. These carbohydrate biopolymers have been extensively used for environmental applications because they are bio-degradable, bio-compatible, non-toxic and inexpensive. Recently, carbohydrate biopolymers have been used to prepare different nanocomposite adsorbents for treatment of wastewater. These adsorbents explored the removal effectiveness of inorganic pollutants from aqueous solution. This review article discusses the synthesis and application of chitosan, carboxymethyl cellulose, alginate and lignin nanocomposites as adsorbents for heavy metals. Toxic metals can be efficiently absorbed by cross-linkers, distributed in aqueous solutions of divalent heavy metal ions to examine their polymer absorption capacity. These nanocomposites were used for the adsorption of highly toxic metals such as Cd2+, Pb2+ and Zn2+ in water. To make heavy metal ion uptake more effective, more functionalization has been implemented such as blending, grafting, or mixing with different nanomaterials with an extra functional group. The integration of the second part into the main polymer chain not only adds functionality but also increases mechanical efficiency, one of the core criteria for adsorbent recyclability. The remediation method of metal ions from wastewater is cheaper as long as the adsorbent is reused. Furthermore, they exhibited good performance for the reuse of spent adsorbents after adsorption-desorption processes including latent fingerprint detection with nanomaterials by using the powder dusting method. Chitosan, carboxymethyl cellulose, alginate and lignin based nanocomposites have demonstrated better adsorption activities due to great physical and chemical properties for the chelation of heavy metals such as Cd2+, Pb2+ and Zn2+ from water and also higher regeneration with various eluents after several desorption-adsorption cycles. In addition, reuse of the spent adsorbents in latent fingerprint detection with different nanomaterials is discussed. Finally, this review article makes recommendations for future studies in light of environmentally favourable and economical applications.

Lignin-based nanoparticles for recovery and separation of phosphate and reused as renewable magnetic fertilizers

In this work, magnetic lignin-based nanoparticles (M/ALFe) were developed and used to adsorb phosphorus to obtain phosphorus-saturated nanoparticles (M/ALFeP). The nanoparticles were then used as renewable slow-release compound fertilizers. First, aminated lignin was synthesized via Mannich reaction, and then Fe₃O₄ nanoparticles were loaded and Fe³⁺ was chelated on the aminated lignin to prepare M/ALFe. Finally, M/ALFeP were obtained after adsorption of phosphorus. The effects of nanoparticle dosage, solution pH and adsorption time on adsorption efficiency were determined. Adsorption isotherm and adsorption kinetics results suggested that the adsorption was coincided with the pseudo-second-order and Temkin model, respectively. The cumulative release of Fe and phosphorus from M/ALFeP increased gradually and reached to 67.2% and 69.1% in soil after 30 days, respectively. After the release of nutrients, M/ALFeP can be separated by a magnet with a high recovery ratio from water or soil and regenerated for phosphate recovery again. Therefore, the magnetic lignin-based nanoparticles have a promising application potential as an efficiently separated and renewable nanomaterial for removal of low concentration phosphate in wastewater treatment and as a slow-release fertilizer in sustainable agriculture.

Lignin-derived (nano)materials for environmental pollution remediation: Current challenges and future perspectives

The supply of affordable drinking and sufficiently clean water for human consumption is one of the world's foremost environmental problems and a large number of scientific research works are addressing this issue Various hazardous/toxic environmental contaminants in water bodies, both inorganic and organic (specifically heavy metals and dyes), have become a serious global problem. Nowadays, extensive efforts have been made to search for novel, cost effective and practical biosorbents derived from biomass resources with special attention to value added, biomass-based renewable materials. Lignin and (nano)material adorned lignin derived entities can proficiently and cost effectively remove organic/inorganic contaminants from aqueous media. As low cost of preparation is crucial for their wide applications in water/wastewater treatment (particularly industrial water), future investigations must be devoted to refining and processing the economic viability of low cost, green lignin-derived (nano)materials. Production of functionalized lignin, lignin supported metal/metal oxide nanocomposites or hydrogels is one of the effective approaches in (nano)technology. This review outlines recent research progresses, trends/challenges and future prospects about lignin-derived (nano)materials and their sustainable applications in wastewater treatment/purification, specifically focusing on adsorption and/or catalytic reduction/(photo)degradation of a variety of pollutants.

One-pot fabrication of lignin-based aromatic porous polymers for efficient removal of bisphenol AF from water

To remove the bisphenol AF (BPAF) from aqueous solution, two different types of lignin-based aromatic porous polymers (LAPP-1 and LAPP-2) were fabricated via one-pot crosslinking of lignin with 1,4-dichloroxylene and 4,4'-bis(chloromethyl)-1,1'-biphenyl, respectively. The successful synthesis of LAPPs was confirmed by FTIR and XPS, SEM, TEM and N₂ adsorption-desorption analysis. Then, batch adsorption experiments were conducted to investigate adsorption properties toward BPAF. Based on the results, the adsorption processes were in accordance with the pseudo-second-order kinetic model and the Freundlich isotherm model, and the thermodynamic studies showed that the adsorption was a spontaneous and exothermic process. It is remarkable that LAPPs exhibited good adsorption performance in wide ranges of pH and ionic strength as well as in recycling process. Notably, compared to LAPP-1, LAPP-2 exhibited higher adsorption capacity for BPAF, which can be ascribed to its higher porosity and content of aromatic ring. Moreover, the comprehensive analysis of experimental and theoretical results indicated that the π-π interactions and pore adsorption may jointly drive the uptake process of BPAF. Considering the simple fabrication method employed and excellent BPAF adsorption performance, LAPPs provided new insights into the development of advanced lignin-based adsorbents for removal of BPAF from water.

Copper Adsorption on Lignin for the Removal of Hydrogen Sulfide

Lignin is currently an underutilized part of biomass; thus, further research into lignin could benefit both scientific and commercial endeavors. The present study investigated the potential of kraft lignin as a support material for the removal of hydrogen sulfide (H2S) from gaseous streams, such as biogas. The removal of H2S was enabled by copper ions that were previously adsorbed on kraft lignin. Copper adsorption was based on two different strategies: either directly on lignin particles or by precipitating lignin from a solution in the presence of copper. The H2S concentration after the adsorption column was studied using proton-transfer-reaction mass spectrometry, while the mechanisms involved in the H2S adsorption were studied with X-ray photoelectron spectroscopy. It was determined that elemental sulfur was obtained during the H2S adsorption in the presence of kraft lignin and the differences relative to the adsorption on porous silica as a control are discussed. For kraft lignin, only a relatively low removal capacity of 2 mg of H2S per gram was identified, but certain possibilities to increase the removal capacity are discussed.

How does the microenvironment change during the stabilization of cadmium in exogenous remediation sediment?

The pollution degree of heavy metals is closely related to the sediment microenvironment. This study aims to give a comprehensive account of the changes of microenvironment in sediment during the stabilization of cadmium (Cd) by the sodium lignosulphonate (SLS) modified chlorapatites (SLS@nClAP). Chemical speciation change demonstrated that SLS@nClAP possessed better stabilizing capacity (65.84 %-76.66 %) for Cd than unmodified chlorapatites (ClAP) (45.88 %). It might be since that the surface of SLS@nClAP presented a more dispersive thin sheet structure with sulfonate groups compared with the aggregate block structure of ClAP. High-throughput sequencing results displayed that succession of microbial community occurred after remediation in sediment. Most importantly, the dominant genus changed from massilia to phosphate-solubilizing bacterium-pseudomonas which might be due to the remediation of chlorapatites and the stabilization of Cd. Moreover, enzyme activity changes showed that the activity of catalase and urease were highly influenced by the stability and bioavailability of Cd during the incubation. This study not only provided a novel remediation technology for Cd-polluted sediment but also confirmed that the change of microenvironment was closely related to the stability and bioavailability of Cd in sediment.

Lignin-Based Nanoparticles: A Review on Their Preparations and Applications

Lignin is the most abundant by-product from the pulp and paper industry as well as the second most abundant natural renewable biopolymer after cellulose on earth. In recent years, transforming unordered and complicated lignin into ordered and uniform nanoparticles has attracted wide attention due to their excellent properties such as controlled structures and sizes, better miscibility with polymers, and improved antioxidant activity. In this review, we first introduce five important technical lignin from different sources and then provide a comprehensive overview of the recent progress of preparation techniques which are involved in the fabrication of various lignin-based nanoparticles and their industrial applications in different fields such as drug delivery carriers, UV absorbents, hybrid nanocomposites, antioxidant agents, antibacterial agents, adsorbents for heavy metal ions and dyes, and anticorrosion nanofillers.

Effects of Cationic Cetyltrimethylammonium Bromide on the Aggregation Behavior of Sodium Lignosulfonate (NaLS) in Concentrated Solutions and Preparation of Uniform Lignosulfonate-Based Colloidal Spheres

The effects of cetyltrimethylammonium bromide (CTAB) on the aggregation behavior of sodium lignosulfonate (NaLS) in concentrated solutions were investigated by rheology, conductivity, ζ-potential, surface tension, contact angle, and elemental analysis measurements. Results showed that the presence of CTAB led to increased aggregate effects and enhanced association networks due to intermolecular bridging caused by the formation of mixed aggregates containing NaLS hydrophobes and CTAB molecules at CTAB/NaLS mixing ratios (w/w) below stoichiometric mass ratio (SMR). However, further addition of CTAB resulted in the progressive disruption of network structures due to electrostatic repulsions between aggregates. There were electrostatic and hydrophobic interactions between NaLS and CTAB. The NaLS/CTAB mixing system could form regular colloidal spheres via electrostatic and hydrophobic self-assembly in an EtOH/water mixture. As the addition of CTAB increased, the ζ-potential of NaLS/CTAB colloidal spheres was decreased, and the particle size was increased. This work provides a novel approach to the value-added utilization of lignosulfonate biomass resources.

"Waste to Wealth": Lignin as a Renewable Building Block for Energy Harvesting/Storage and Environmental Remediation

Lignin is the second most earth-abundant biopolymer having aromatic unit structures, but it has received less attention than other natural biomaterials. Recent advances in the development of lignin-based materials, such as mesoporous carbon, flexible thin films, and fiber matrix, have found their way into applications to photovoltaic devices, energy-storage systems, mechanical energy harvesters, and catalytic components. In this Review, we summarize and suggest another dimension of lignin valorization as a building block for the synthesis of functional materials in the fields of energy and environmental applications. We cover lignin-based materials in the photovoltaic and artificial photosynthesis for solar energy conversion applications. The most recent technological evolution in lignin-based triboelectric nanogenerators is summarized from its fundamental properties to practical implementations. Lignin-derived catalysts for solar-to-heat conversion and oxygen reduction are discussed. For energy-storage applications, we describe the utilization of lignin-based materials in lithium-ion rechargeable batteries and supercapacitors (e.g., electrodes, binders, and separators). We also summarize the use of lignin-based materials as heavy-metal adsorbents for environmental remediation. This Review paves the way to future potentials and opportunities of lignin as a renewable material for energy and environmental applications.

Cellulose for the effective decontamination of water pollution

The widespread industrialization, urbanization, and technological development have triggered the daily release of considerable amounts of pollutants, specifically in aquatic environments. Previous research and work-studies indicate the existence of defined properties, such as low cost, non-toxicity, biodegradability, reusability, and easy synthesis, preparation or extraction, which make a material an ideal agent for the remediation of water or the environment. Therefore, the scientific community has focused on the development and study of several novels, environmentally friendly, and cost-effective materials. Cellulose is the most abundant natural polymer encountered worldwide. Thereby, due to the unique biological properties that this biopolymer possesses, it has emerged as a potential candidate to replace synthetic materials for practical bioremediation of contaminated water. Furthermore, the presence of hydroxyl groups on its surface makes this biopolymer highly malleable, thus significantly enhancing its physicochemical properties by using a wide variety of functional groups and modification methods. The present review describes the different biopolymers useful for remediation of environmental pollution, explores in more detail the characteristics of cellulose and its promising applications in the decontamination of water pollution, and pays special attention to the removal of heavy metal ions, dyes, and hydrophobic organic compounds.

Simultaneous removal of methylene blue and Pb2+ from aqueous solution by adsorption on facile modified lignosulfonate

In this paper, simultaneous removal of methylene blue (MB) and Pb²⁺ from the binary component system by an easily prepared cross-linked lignosulfonate bio-adsorbent (CLLS) was described. CLLS was characterized by FTIR, SEM/EDS and TGA. The influences of pH, temperature, contact time and initial MB and Pb²⁺ concentrations on the adsorption performance were investigated. The results demonstrated a good ability of CLLS to remove MB and Pb²⁺ simultaneously. Using of 1.0 g L^-1 loading, removal efficiency of MB and Pb²⁺ reached 98.0% and 97.8%, respectively, in the MB (100 mg.L^-1)-Pb²⁺ (50 mg.L^-1) system. Moreover, the adsorption isotherms and adsorption kinetics indicated that the results were fitting well with the Langmuir and pseudo-second-order model, respectively, for both MB and Pb²⁺. Based on the Langmuir model, the maximum adsorption capacity of MB and Pb²⁺ reached 132.6 and 64.9 mg g^-1, respectively, in the MB-Pb²⁺ system, which was much lower than that in the single component system (358.4 mg g^-1 100.9 mg g^-1 for MB and Pb²⁺, respectively). Hence, simultaneous adsorption of MB and Pb²⁺ onto CLLS was an antagonistic adsorption. In addition, an apart-sequential adsorption method was used to study the action of adsorption sites on CLLS for MB and/or Pb²⁺ with the help of an efficient self-made apparatus. Rudimental results showed that there would be three different kinds of adsorption sites on CLLS: MB-site, Pb²⁺-site and MB/Pb²⁺- shared sites. Furthermore, in the MB (100 mg.L^-1)-Pb²⁺(50.0 mg.L^-1) system, the simultaneous removal efficiency of MB and Pb²⁺ still maintained 91.8% and 85.0%, respectively, after 6 cycles.

Synthesis of Chitosan-Ignosulfonate Composite as an Adsorbent for Dyes and Metal Ions Removal from Wastewater

Sodium lignosulfonate is a polymer with extensive sources and abundant functional groups. Therefore, it has potential value for research and wide utilization. In this study, the adsorption material was prepared by blending sodium lignosulfonate and chitosan, which could adsorb anionic and cationic dyes and metal ions. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetry (TG). The results showed that the composite was cross-linked mainly by the strong electrostatic interaction between the protonated amino group in chitosan and the sulfonate group in sodium lignosulfonate. Moreover, the effects of initial concentration, adsorption time, initial pH, and mass ratio of chitosan to sodium lignosulfonate on the adsorption performance of the composite were investigated. Meanwhile, the adsorption processes were agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model. The adsorption mechanism was that the electrostatic interaction between the protonated amino and hydroxyl groups of the composite with anionic (SO3 -) and HCrO4 - groups of Congo red and Cr(VI), respectively. In addition, the electrostatic interaction between SO3 - of the composite and positively charged group of Rhodamine B played an important role in the adsorption of Rhodamine B.

A dual-responsive biosensor for blood lead detection

Simple and accurate detection of trace heavy metals in blood is very important. A novel dual-responsive electrochemical/fluorescent biosensor based on magnetic hyperbranched polyamide with heparin modification (MHPAM-H) for blood lead detection has been successfully developed. Upon conjugated with blood lead ions, dual-biosensor could not only display electrochemical signal but also fluorescence signal owing to the enriched amino groups, cavity structure, and good fluorescence properties of HPAM. Blood biocompatibility, construction of the dual-responsive biosensor, electrochemical/fluorescent detection of lead ions in water phase and blood condition, selectivity and stability of the dual-responsive biosensor were investigated in detail. The proposed dual-responsive biosensor displays good linear relationship (1.5 pM- 4.8 × 10³ pM for electrochemical detection and 0.5 pM-4.8 × 10³ pM for fluorescent detection) with low detection limit (4.4 pM for electrochemical detection and 1.0 pM for fluorescent detection) for blood lead, providing potential application for blood lead detection in the future.

Fabrication of magnetic lignosulfonate using ultrasonic-assisted in situ synthesis for efficient removal of Cr(Ⅵ) and Rhodamine B from wastewater

A novel and eco-friendly one-step approach has been developed to fabricate magnetic lignosulfonate (MLS) with high performance in wastewater treatment. The obtained MLS was characterized by FTIR, XRD, SEM, TEM, VSM. The results showed that MLS had a good magnetic behavior in an applied magnetic field and its saturation magnetization intensity was up to 43.98 emu/g. Moreover, MLS exhibited excellent adsorption properties for Cr(Ⅵ) (57.14 mg/g) and Rhodamine B (22.47 mg/g). Simultaneously, the adsorption kinetics and adsorption isotherm experiments indicated that the data was agreed well with the pseudo-second-order and Langmuir model, respectively. After five regeneration cycles, the desorption efficiencies of Cr(Ⅵ) and Rhodamine B could reach more than 70% and 85%, respectively. Hence, the magnetic lignosulfonate is a promising material as a highly adsorptive and recyclable adsorbent for removing metal ions and cationic pollutants in wastewater.

Preparation of a Novel Lignin Nanosphere Adsorbent for Enhancing Adsorption of Lead

Carboxymethyl lignin nanospheres (CLNPs) were synthesized by a two-step method using microwave irradiation and antisolvent. The morphology and structure of CLNPs were characterized by ³¹P-NMR, FTIR, and SEM, and the results showed that they had an average diameter of 73.9 nm, a surface area of 8.63 m² or 3.2 times larger than the original lignin, and abundant carboxyl functional groups of 1.8 mmol/g. The influence of dosage, pH, contact time, and concentration on the adsorption of metal ions onto CLNPs were analyzed, and the maximum adsorption capacity of CLNPs for Pb(II) was found to be 333.26 mg/g, which is significantly higher than other lignin-based adsorbents and conventional adsorbents. Adsorption kinetics and isotherms indicated that the adsorption of lead ions in water onto CLNPs followed the pseudo-second-order model based on monolayer chemisorption mechanism. The main chemical interaction between CLNPs and lead ions was chelation. CLNPs also showed an excellent recycling performance, with only 27.0% adsorption capacity loss after 10 consecutive adsorption–desorption cycles.

Lignin xanthate resin-bentonite clay composite as a highly effective and low-cost adsorbent for the removal of doxycycline hydrochloride antibiotic and mercury ions in water

Natural-occurring polymer intercalated inorganic clay composites have received increasing interests in water cleanup for the features of eco-friendliness, cost-effectiveness, and availability. Herein, a new lignin xanthate resin (LXR) intercalated bentonite clay composite (LXR-BT) for the adsorption of representative organic doxycycline hydrochloride (DCH) antibiotic and inorganic Hg(II) in water was created through a feasible process. Structural characterizations by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Thermo gravimetric analysis (TG), and scanning electron microscopy (SEM) confirmed LXR was successfully intercalated between the layers of bentonite clay. The adsorption performance of DCH/Hg(II) by LXR-BT was studied in detail with varied dosage, solution pH, contact time, and initial DCH/Hg(II) concentration. The results indicated that the adsorption capacities of DCH/Hg(II) on LXR-BT were much higher than that on bentonite, and the adsorption kinetics and isotherms followed the pseudo-second-order model and Langmuir model, respectively. X-ray photoelectron spectroscopy (XPS) analysis confirmed the adsorption mechanisms of DCH (or Hg(II)) was mainly due to π-π interaction and hydrogen bonding interaction of DCH (or the complexation of Hg(II)) with the functional groups in the LXR-BT. This study suggested the possibility of LXR-BT as a new cost-effective adsorbent for both organic and inorganic pollutants removal in water.