Waste Lignin Research Articles

One-pot synthesis of Fe modified lignin biochar for ex-situ catalytic fast pyrolysis of enzymatic hydrolysis lignin to promote the generation of aromatic hydrocarbons

The utilization of waste lignin to produce bio-oil rich in aromatics aromatic hydrocarbons is promising and attractive for a wide range of applications. Fe-modified lignin biochar (xFe/ALC) prepared using a one-step method was utilized as catalysts to investigate their impact on product distribution, aromatic hydrocarbon generation, and pathways during ex-situ catalytic fast pyrolysis of enzymatic hydrolysis lignin. The results revealed that the addition of Fe enhanced the production of gas products such as H2, while decreasing bio-oil yield. The lowest bio-oil yield, at 12.10 wt%, was observed at a Fe loading of 25 wt%, however the relative content of aromatic hydrocarbons reached a maximum value of 16.24 area%. Compared to the pyrolysis of lignin alone, their contents increased by 2.46 times, with the content of monocyclic aromatic hydrocarbons (toluene, ethylbenzene, styrene, xylene) increasing by 1.5–3.8 times. Spent 25Fe/ALC had good stability on the production of aromatic hydrocarbons. Compared with non-catalytic pyrolysis of lignin, the aromatic hydrocarbons content for spent 25Fe/ALC after four cycles increased by 26.70%.

Engineering a Carotenoid Cleavage Oxygenase for Coenzyme-Free Synthesis of Vanillin from Ferulic Acid.

One-pot biosynthesis of vanillin from ferulic acid without providing energy and cofactors adds significant value to lignin waste streams. However, naturally evolved carotenoid cleavage oxygenase (CCO) with extreme catalytic conditions greatly limited the above pathway for vanillin bioproduction. Herein, CCO from Thermothelomyces thermophilus (TtCCO) was rationally engineered for achieving high catalytic activity under neutral pH conditions and was further utilized for constructing a one-pot synthesis system of vanillin with Bacillus pumilus ferulic acid decarboxylase. TtCCO with the K192N-V310G-A311T-R404N-D407F-N556A mutation (TtCCOM3) was gradually obtained using substrate access channel engineering, catalytic pocket engineering, and pocket charge engineering. Molecular dynamics simulations revealed that reducing the site-blocking effect in the substrate access channel, enhancing affinity for substrates in the catalytic pocket, and eliminating the pocket's alkaline charge contributed to the high catalytic activity of TtCCOM3 under neutral pH conditions. Finally, the one-pot synthesis of vanillin in our study could achieve a maximum rate of up to 6.89 ± 0.3 mM h-1. Therefore, our study paves the way for a one-pot biosynthetic process of transforming renewable lignin-related aromatics into valuable chemicals.

Simple and scalable preparation of lignin based porous carbon coated nano-clay composites and their efficient removal for the diversified iodine

Here, lignin and nano-clay were used to prepare novel composite adsorbents by one-step carbonization without adding activators for radioactive iodine capture. Specially, 1D nano-clay such as halloysite (Hal), palygorskite (Pal) and sepiolite (Sep) were selected as skeleton components, respectively, enzymatic hydrolysis lignin (EHL) as carbon source, lignin based porous carbon/nano-clay composites (ELC-X) were prepared through ultrasonic impregnation, freeze drying, and carbonization. Characterization results indicated lignin based porous carbon (ELC) well coated on the surface of nano-clay, and made its surface areas increase to 252 m2/g. These composites appeared the micro-mesoporous hierarchical structure, considerable N doping and good chemical stability. Results of adsorption experiments showed that the introduction of ELC could well promote iodine vapor uptake of nano-clay, and up to 435.0 mg/g. Meanwhile, the synergistic effect between lignin based carbon and nano-clay was very significant for the adsorption of iodine/n-hexane and iodine ions, their capacity were far exceed those of a single material, respectively. The relevant adsorption kinetic and thermodynamics, and mechanism of ELC-X composites were clarified. This work provided a class of low-cost and environmentally friendly adsorbents for radioactive iodine capture, and opened up ideas for the comprehensive utilization of waste lignin and natural clay minerals.

Bifunctional nanocomposites formed from magnetic lignin-derived carbon and molybdenum disulfide for efficient pollutant removal

The development of inexpensive and robust bifunctional nanocomposites toward efficient pollutant removal is crucial for wastewater remediation. Herein, we report a novel strategy for fabrication of magnetic nanocomposites loaded with molybdenum disulfide (Fe3O4/PLC-MoS2) using lignin biomacromolecules for efficient pollutant removal. The Fe3O4/PLC-MoS2 exhibit excellent pollutant removal capacity: The adsorption capacity of Pb(II) achieve 236.1 mg/g and the methylene blue (MB) degradation rate is up to 90.0 % within 20 min. The adsorption mechanism reveal that the enhanced removal properties is due to that the S atoms on the loaded MoS2 could convert into soluble sulfide and react with Pb(II) to form white precipitate β-Pb3O2SO4. Moreover, the experiments results demonstrate that the Fe3O4/PLC-MoS2 has a low bandgap, which can activate PMS to produce reactive oxygen species and degrade MB molecules efficiently. Notably, the Fe3O4/PLC-MoS2 demonstrate continued outstanding wastewater remediation capabilities even in scenarios where Pb(II) and MB coexisted. Overall, this study offers a viable and eco-friendly design of dual function removal material by using lignin waste toward promising implications for wastewater treatment.

Evaluating the effect of paper waste lignin in hot mix asphalt

Asphalt is a viscoelastic material which performs to resist rutting, fatigue cracking, and moisture susceptibility under different loading and temperature conditions. The use of innovative and renewable pavement construction materials is inevitable due to high axle loads, rapidly increasing traffic volumes, and varying climatic conditions. This study aims to assess the effect as well as the optimum dosage of paper waste lignin for use in hot mix asphalt (HMA). Lignin from the paper industry with dosage ratios of 5, 10, 15, and 20%, was utilized to study the effect of the addition of lignin to the asphalt binder. Virgin and lignin-modified binder samples, before and after the aging process, were subjected to physical testing through penetration, softening point, ductility, viscosity and specific gravity and rheological characteristics through dynamic shear rheometer (DSR), bending beam rheometer (BBR), and rational viscometer (RV). The fractional composition was assessed through saturates, aromatics, resins and asphaltenes (SARA) fractional composition technique. Statistical analysis was also performed to find correlation of different physical and rheological parameters. Furthermore, based on optimum dosage, the performance of asphalt mixtures was studied against rutting, fatigue cracking, and moisture susceptibility. The results indicated that the addition of lignin has improved the physical properties significantly. The amount of asphaltene decreased and aromatics increased in SARA fractional analysis. Moreover, the Colloidal Instability Index (CII) has also indicated a stable structure of the binder. The rheological characteristics are improved after modification. The asphalt mixture tests revealed that addition of lignin with optimum dosage (10%) has improved the performance against rutting, fatigue cracking and moisture susceptibility. Statistical analysis indicated good co-relation among different physical and rheological parameters. This study concludes that 10% dosage is the optimum dosage that can successfully replace the virgin asphalt binder for performance of hot mix asphalt.

Synthesis of lignin-based resin and fabrication of sustainable transparent wood based on bio-recycling concept

Transparent wood (TW) has attracted much attention in the field of energy saving building structural materials because of its high light transmittance, good thermal insulation performance and good toughness. However, the polymeric resins used in the present study to impregnate lignin-based wood templates are usually derived from petroleum-based chemical resources, which pose a fatal threat to human beings both in terms of consuming large amounts of resources and causing environmental pollution problems. It is therefore important to develop alternatives to petroleum-derived chemicals in renewable natural resources. Here, we report a green and sustainable TW production process based on the bio-recycling concept. Lignin-based sustainable resin (LSR) was prepared from waste lignin produced during delignification by polymerization of guaiacol. At the same time, according to FT-IR and NMR data analysis combined with previous studies, the synthesis mechanism of LSR was proposed, and this result provided a reference for bio-based resins made from biomass materials. The prepared lignin-based sustainable transparent wood (LSTW) has good light transmittance and good dimensional stability. In addition, the LSTW also shows good thermal insulation and indoor temperature regulation capabilities compared with the common glass.

Ligin-derived graphene-like ultrathin carbon materials for ORR catalysis

Low-cost nitrogen-doped carbon materials with graphene-like structures were designed and prepared from extensive renewable biomass waste lignin. The obtained carbon materials exhibited well-designed ultrathin two-dimensional structures with high specific area and mesoporous characteristics. Benefiting from the well-designed structures with extensive catalytic active sites and efficient mass transfer and diffusion, as well as the modified electronic characteristics from nitrogen doping, the lignin-derived carbon materials exhibited pronounced ORR catalytic activity and methanol tolerance. Considering these, the lignin-derived carbon materials hold great application potentials as ORR catalysts and catalyst supports.

Bioremediation of Kraft Lignin in Wastewater: Optimization of Temperature and Isolation of Valuable Compounds

Conventional methods for the treatment of complex lignin found in the pulp and paper mill effluent is a strenuous and expensive process. Microbial degradation is a promising technique to degrade lignin efficiently due to its adaptability and rapid growth of microbes in diverse environments. This study is focused on the isolation of potential ligninolytic bacterial strains from agricultural soil and decomposed wood sources for successful degradation of lignin present in the wastewater. Initially, 15 ligninolytic strains were identified and three dominant species, Staphylococcus lentus (SB5), Bacillus megaterium (RWB15) and Pseudomonas geniculata (RWP9) were isolated as per their growth tolerance pattern with different lignin concentrations. The lignin degradation study was carried out at different temperatures (25-45℃) with 1000 mg/l of feed lignin concentrations. The optimum degradation temperature of all the strains fell within the range 30-35℃. The maximum lignin degradation of SB5, RWB15 and RWP9 was identified as 89, 77 and 90% at the end of the 6th, 3rd and 7th day of biodegradation, respectively. There was a steep reduction of COD by all three microbes before attaining the stationary phase and thereafter COD reduction was sluggish due to the death phase. Besides, the microbes used in this study showed the transformation of lignin into valuable low-molecular by-products, vanillin, vanillic acid and adipic acid with their concentration being quantified as 28, 101 and 130 mg/l, respectively. This study shows the successful degradation of waste lignin and the recovery of valuable byproducts from waste streams.

Copper-catalyzed C–C bond cleavage coupling with C[tbnd]N bond formation toward mild synthesis of lignin-based benzonitriles

N-participated lignin depolymerization is of great importance for the transformation of waste lignin into value-added chemicals. The vast majority of developed strategies employ organic amines as nitrogen source, and considerable methods rely on excessive use of strong base, which suffers severe environmental issues. Herein, benzonitrile derivatives are synthesized from oxidized lignin β-O-4 model compounds in the presence of solid nitrogen source (NH4)2CO3 under mild, base-free conditions over commercially available copper catalyst. Mechanism studies suggest the transformation undergoes a one-pot, highly coupled cascade reaction path involving oxidative C-C bond cleavage and in-situ formation of CN bond. Of which, Cu(OAc)2 catalyzes the transfer of hydrogen from Cβ (Cβ-H) to Cα, leading to the cleavage of Cα-Cβ bonds to offer benzaldehyde derivative, this intermediate then reacts in-situ with (NH4)2CO3 to afford the targeted aromatic nitrile product. Tetrabutylammonium iodide (TBAI), acting as a promoter, plays a key role in breaking the Cα-Cβ bonds to form the intermediate benzaldehyde derivative. With this protocol, the feasibility of the production of value-added syringonitrile from birchwood lignin has been demonstrated. This transformation provides a sustainable approach to benzonitrile chemicals from renewable source of lignin.

Challenges and Perspectives of the Conversion of Lignin Waste to High-Value Chemicals by Pyrolysis

The pyrolysis process is a thermochemical conversion reaction that encompasses an intricate array of simultaneous and competitive reactions occurring in oxygen-depleted conditions. The final products of biomass pyrolysis are bio-oil, biochar, and some gases, with their proportions determined by the pyrolysis reaction conditions and technological pathways. Typically, low-temperature slow pyrolysis (reaction temperature below 500 °C) primarily yields biochar, while high-temperature fast pyrolysis (reaction temperature 700–1100 °C) mainly produces combustible gases. In the case of medium-temperature rapid pyrolysis (reaction temperature around 500–650 °C), conducted at very high heating rates and short vapor residence times (usually less than 1 s), the maximum liquid yield can reach up to 85 wt% (on a wet basis) or achieve 70 wt% (on a dry basis), with bio-oil being the predominant product. By employing the pyrolysis technique, valuable utilization of tobacco stem waste enriched with lignin can be achieved, resulting in the production of desired pyrolysis products such as transportation fuels, bio-oil, and ethanol. The present review focuses on catalytic pyrolysis, encompassing catalytic hydropyrolysis and catalytic co-pyrolysis, and meticulously compares the impact of catalyst structure on product distribution. Initially, we provide a comprehensive overview of the recent pyrolysis mechanism of lignin and tobacco waste. Subsequently, an in-depth analysis is presented, elucidating how to effectively design the catalyst structure to facilitate the efficient conversion of lignin through pyrolysis. Lastly, we delve into other innovative pyrolysis methods, including microwave-assisted and solar-assisted pyrolysis.

Microwave-assisted pyrolysis of waste lignin to prepare biochar for Cu2+ highly-efficient adsorption: Performance, kinetics and mechanism resolution

Alkali lignin is the major byproduct of the paper-making industry and biorefining processes. However, due to its complex structure and low reactivity, most alkali lignin is still discharged as “black liquor” or directly incinerated, resulting in significant waste of bioresources and severe environmental pollution. In this study, biochar was prepared from alkali lignin using microwave-assisted pyrolysis, and its adsorption performance and mechanism for Cu2+ were investigated. The experimental findings demonstrate that the adsorption of Cu2+ onto biochar follows the pseudo-second-order kinetic model and the Langmuir isotherm model, suggesting that the adsorption process is predominantly governed by the chemisorption mechanism. Furthermore, the qm ranged from 405.55 to 492.75 mg·g−1, which is significantly higher than many other reported biochars. The adsorption mechanism includes mineral co-precipitation, DOM (mainly humic substances) adsorption, surface complexation, as well as ion exchange. The contribution of co-precipitation and surface complexation reaches 86.6 %, indicating that this biochar poses a low environmental risk. Thus, this study shows that alkali lignin could be a valuable bioresource for mitigating the environmental impact arising from Cu2+ pollution.

Construction of novel phytic acid-based lignin for highly efficient treatment of low-level radioactive wastewater: Synthesis, performance, and mechanistic insights

Low-level radioactive wastewater exhibits a serious jeopardize to the ecology, natural environment, and human health. Hence, this study constructed a novel adsorbent (PA-EHL) via a simple grafting reaction by using enzymatic hydrolysis lignin waste (EHL) and phytic acid (PA) as raw materials. The adsorption capacity of PA-EHL was evaluated using Ce(III) and La(III) as the representative nuclides. PA grafting significantly promoted the formation of good textural properties, high crystalline stability, and abundant phosphorous/oxygen-containing functional groups on lignin surface, thus appreciably strengthening the adsorption performance. The PA-EHL exhibited high adsorption capacity for Ce(III) with 743.16 and for La(III) with 735.60 mg/g within 240 min. In addition, the efficient ability of PA-EHL for adsorbing Ce(III) and La(III) displayed superior anti-ions interference abilities, excellent reusability, and extremely low operational fees. The P-O on PA-EHL surface as the main active site, displayed strong binding affinity for Ce(III) and La(III) via electrostatic attraction-dominated physisorption and complexation-dominated chemisorption, respectively. In summary, the constructed PA-EHL addresses the drawback of conventional adsorbents in view of complicated fabrication process, low adsorption capacity, inferior anti-ions interference abilities, and expensive cost, which makes it as a potential adsorbent in industrial application for the highly efficient treatment of low-level radioactive wastewater.

Fractionation and purification of a high-impurity, alkaline-pretreated, corn stover lignin with simple renewable solvents

Corn stover has been identified as a key resource in the transition from petrochemicals to sustainably sourced energy and materials; however, the as-recovered lignin from alkaline pretreatment contains unusually high levels of residual impurities, which must be removed to maximize potential application. Thus, the Aqueous Lignin Purification using Hot Agents (ALPHA) process was applied to a corn stover lignin containing ∼10 % carbohydrates and ∼3 % ash. Lignin fractions ∼100 times cleaner than the feed lignin and of controlled molecular weight (i.e., as low as one-fifth and as high as triple the absolute molecular weight (Mw) of the feed) were obtained. The ALPHA solvent was a hot (60 or 75 °C) solution of 80 % ethanol combined with the feed lignin at an unusually low, 3:1 solvent-to-feed lignin ratio – conditions that create the liquid–liquid equilibrium (LLE) phase split needed to practice ALPHA. Lignin fractionation then commenced by adding water to the original solution, decreasing the ethanol content in increments of 3–4 wt%. Surprisingly, the highest Mw fractions did not precipitate until the solution contained just below 50 % ethanol, by which point almost half of the starting lignin of near-average Mw had already precipitated. Another unexpected result was that the lignin waste stream from the initial purification step could be increased from 40 to 98 % lignin in a single equilibrium stage simply by re-processing that waste with another 80 % ethanol solution at the conditions given above. In summary, the efficacy of ALPHA for purifying and fractionating an impurities-laden corn stover lignin to ultraclean levels in a scalable manner requiring only aqueous bioethanol solutions has been demonstrated.

Recycled Waste as Polyurethane Additives or Fillers: Mini-Review.

The intensive development of the polyurethanes industry and limited resources (also due to the current geopolitical situation) of the raw materials used so far force the search for new solutions to maintain high economic development. Implementing the principles of a circular economy is an approach aimed at reducing the consumption of natural resources in PU production. This is understood as a method of recovery, including recycling, in which waste is processed into PU, and then re-used and placed on the market in the form of finished sustainable products. The effective use of waste is one of the attributes of the modern economy. Around the world, new ways to process or use recycled materials for polyurethane production are investigated. That is why innovative research is so important, in which development may change the existing thinking about the form of waste recovery. The paper presents the possibilities of recycling waste (such as biochar, bagasse, waste lignin, residual algal cellulose, residual pineapple cellulose, walnut shells, silanized walnut shells, basalt waste, eggshells, chicken feathers, turkey feathers, fiber, fly ash, wood flour, buffing dust, thermoplastic elastomers, thermoplastic polyurethane, ground corncake, Tetra Pak®, coffee grounds, pine seed shells, yerba mate, the bark of Western Red Cedar, coconut husk ash, cuttlebone, glass fibers and mussel shell) as additives or fillers in the formulation of polyurethanes, which can partially or completely replace petrochemical raw materials. Numerous examples of waste applications of one-component polyurethanes have been given. A new unexplored niche for the research on waste recycling for the production of two components has been identified.

Hierarchical beta zeolites assisted aromatics production from lignin via catalytic fast pyrolysis

Converting lignin waste into aromatics is a challenging but crucial aspect of lignin valorization. Although ZSM-5 zeolite is extensively used in lignin deoxygenation, its 10-membered ring (MR) channels limit the diffusion of bulky phenols and tend to produce coke. Herein, a series of 12-MR beta zeolites with varying acidity and hierarchical porosity were synthesized for lignin catalytic fast pyrolysis (CFP). An optimal lignin pyrolysis temperature of 600 °C was initially selected. Subsequently, lignin CFP demonstrated that beta zeolite with medium acidity facilitated aromatics production, with Beta(36) even outperforming ZSM-5(36). The introduction of mesopores further enhanced lignin deoxygenation and the hierarchical B36-0.3-24 increased aromatics selectivity to 56.0 area%, which was 1.5 times that of Beta(36). Combined with the CFP of model compounds (vanillin and catechol), it was inferred that the mesopores and weak acidity played a key role in heavy phenols conversion and aromatics production. In addition, B36-0.3-24 exhibited outstanding reusability in pyrolysis regeneration cycles, underscoring its potential for practical application in lignin valorization.

Effect of Liquid Glass-Modified Lignin Waste on the Flammability Properties of Biopolyurethane Foam Composites.

Water-blown biopolyurethane (bioPUR) foams are flammable and emit toxic gases during combustion. Herein, a novel approach suggested by the current study is to use different amounts of lignin waste (LigW), which increases the thermal stability and delays the flame spread and sodium silicate (LG), which has foaming ability at high temperatures and acts as a protective layer during a fire. However, there have been no studies carried out to investigate the synergy between these two materials. Therefore, two different ratios, namely 1/1 and 1/2 of LigW/LG, were used to prepare bioPUR foam composites. The obtained bioPUR foam composites with a 1/2 ratio of LigW/LG exhibited inhibition of flame propagation during the ignitability test by 7 s, increased thermal stability at higher temperatures by 40 °C, reduced total smoke production by 17%, reduced carbon monoxide release by 22%, and increased compressive strength by a maximum of 123% and 36% and tensile strength by a maximum of 49% and 30% at 100 °C and 200 °C, respectively, compared to bioPUR foam composites with unmodified LigW. Additionally, thanks to the sufficient compatibility between the polymeric matrix and LigW/LG particles, bioPUR foam composites were characterised by unchanged or even improved physical and mechanical properties, as well as increased glass transition temperature by 16% compared to bioPUR foam composites with unmodified LigW particles, making them suitable for application as a thermal insulating layer in building envelopes.

Theoretical insight of reactive oxygen species scavenging mechanism in lignin waste depolymerization products.

Apart from natural products and synthesis, phenolic compounds can be produced from the depolymerization of lignin, a major waste in biofuel and paper production. This process yields a plethora of aryl propanoid phenolic derivatives with broad biological activities, especially antioxidant properties. Due to its versatility, our study focuses on investigating the antioxidant mechanisms of several phenolic compounds obtained from renewable and abundant resources, namely, syringol (Hs), 4-allylsyringol (HAs), 4-propenylsyringol (HPns), and 4-propylsyringol (HPs). Employing the density functional theory (DFT) approach in conjunction with the QM-ORSA protocol, we aim to explore the reactivity of these compounds in neutralizing hydroperoxyl radicals in physiological and non-polar media. Kinetic and thermodynamic parameter calculations on the antioxidant activity of these compounds were also included in this study. Additionally, our research utilizes the activation strain model (ASM) for the first time to explain the reactivity of the HT and RAF mechanisms in the peroxyl radical scavenging process. It is predicted that HPs has the best rate constant in both media (1.13 × 108 M-1 s-1 and 1.75 × 108 M-1 s-1, respectively). Through ASM analysis, it is observed that the increase in the interaction energy due to the formation of intermolecular hydrogen bonds during the reaction is an important feature for accelerating the hydrogen transfer process. Furthermore, by examining the physicochemical and toxicity parameters, only Hs is not suitable for further investigation as a therapeutic agent because of potential toxicity and mutagenicity. However, overall, all compounds are considered potent HOO˙ scavengers in lipid-rich environments compared to previously studied antioxidants.

Improvement of Warm-Mix Asphalt Concrete Performance with Lignin Obtained from Bioethanol Production from Forest Biomass Waste

This study aims to assess the effect of adding lignin waste, a by-product of bioethanol production from forest biomass, to asphalt concrete to improve its performance. After adjusting the lignin content based on preliminary Marshall tests, 20% of this by-product by mass of bitumen was added to the asphalt concrete blends via the dry method. This lignin content was suitable to the temperature was decreased 40 °C compared to the usual mixing temperature, thus allowing the production of warm-mix asphalt concrete (WMA) without any other additive. Tests on a gyratory compactor assessed the workability of the studied asphalt concrete, allowing us to obtain these findings. Moreover, lignin improved moisture damage and adhesion resistance between the binder film and the aggregate particles’ surface. The behaviour at high temperatures was also enhanced, resulting in better resistance to permanent deformation. These promising laboratory results show us an opportunity to create value for this type of by-product in substituting commercial additives for asphalt concrete, such as organic wax or adhesion promoters, to allow the production of warm-mix asphalt concrete with improved properties.

Pseudoplastic liquid mulch film incorporating waste lignin and starch to improve its sprayability and available soil nitrogen

Because traditional slow-release fertilizers cannot effectively retain soil heat and moisture, their ability to increase crop yields is limited. To solve this problem, novel sprayable liquid mulch films (lignin-starch-acrylate, LSA) were prepared with a slow-release urea function, created by emulsion polymerization between lignin (extracted from papermaking waste liquor), starch, and acrylate monomers. The introduction of lignin transformed the LSA emulsion into a pseudoplastic fluid with enhanced sprayability. The presence of lignin in LSA film increased the elongation at break and lowered the Young's modulus, resulting in a film that is more easily pierced by crop seedlings and preserves the heat and moisture of the soil after seedling piercing. Experimental results showed that at a mass ratio of lignin to acrylate monomers of 3/7, the LSA mulch film had good sprayability and film-forming properties, suitable mechanical properties, and the lowest urea release rate. This optimized LSA film exhibited better soil insulation and water retention performance than other slow-release fertilizers. The contents of available soil nitrogen, including NH4+-N and NO3−-N, in soil covered with LSA film were 44.82 and 45.49% higher than those in soil covered with urea, respectively, and the corresponding cabbage yields increased by 33.73%. The results of this study provide a new method for preparing agricultural materials with urea slow-release as well as soil moisture and heat preservation functions.

Facile synthesis of Fe and N co-coped biochar from low temperature pyrolysis of lignin waste for superefficient Th(IV)/U(VI) separation: Performance and mechanism

This study synthesized a nitrogen and iron co-doped biochar (Fe-N/BC) through a facile process of direct pyrolysis from lignin waste at a low temperature. The introduction of Fe and N can not only promote physical properties such as compact pores, high surface area, stable crystal, and magnetically recyclable ability, but also greatly enhance the electron transfer capacity of biochar surface through introducing electrophilic groups, for instance, C-N, pyrrolic N, CO, Fe3+, and C-CO. Moreover, 74.0 mg/g of U(VI) and 360.3 mg/g of Th(IV) was adsorbed by the optimal Fe-N/BC-200, and a high separation index (171147) was obtained. Fe-N/BC outperforms most of biochars from the point of adsorption capacity and cost consumption. Hence, this study reports an economically advantageous method for synthesizing Fe and N co-coped biochar with excellent separation capacity for U(VI)/Th(IV), making it a competitive alternate for other Fe and N co-coped biochar on industrial-scale.