Hydrolysis Lignin Research Articles

Ni-MOFs and lignin modified biochar: An environmentally-friendly and efficient catalyst for catalytic transfer hydrodeoxygenation of lignin derivatives

In this study, different kinds of lignin, including enzymatic hydrolysis of lignin (EHL), alkaline lignin (AL), kraft lignin (KL) and sodium lignosulfonate (LS) were investigated as precursor to prepare Ni@BTC@X (X= EHL, AL, KL, LS) catalysts using a traditional hydrothermal method with Ni-MOF for HDO upgrading of lignin derivative vanillin (VAN) to generate high value chemical 2-methoxy-4-methylphenol (MMP). The catalytic performance of these catalysts was investigated under different reaction conditions, and it was explored that the conversion of VAN was close to 100 % and the MMP yield was close to 90 % under the optimal conditions (Ni@BTC@LS catalyst, 220 ℃, 4 h, isopropanol, 2 MPa N2). Various physical-chemical characterization results verified that the effects of active sites Ni, porous structure of lignin biochar support and electronic properties of the catalysts played a significiant role in HDO of lignin derived VAN. Additionally, synergistic effect of the highly homogeneously dispersed oxygen vacancies and acidic sites also promoted the VAN conversion efficiency. This work developed a strategy combing the advantages of MOFs and biomass derived substrates for manufacturing novel lignin/MOFs materials in the catalytic field.

Development of biopolymer composites using lignin: A sustainable technology for fostering a green transition in the construction sector

Developing sustainable construction materials is important to help reduce the anthropogenic impacts of the construction industry. Currently, the production of concrete accounts for 8 % of global carbon emissions. Therefore, alternatives to concrete must be developed, to reduce its use in the future. New construction materials will help to facilitate a green transition as envisioned in global climate initiatives. Materials such as lignin are ideal, as they can be implemented with little additional cost to manufacture construction materials. We introduce a novel material, lignin-based biopolymer-bound soil composite (BSC), which is similar to other BSCs using other types of biopolymers. In addition, a design methodology is presented, which allows the manufacture of lignin-based BSCs with tailored characteristics. Two kinds of lignin — hydrolysis lignin and alkali lignin — were investigated, with five mix designs developed for each type of lignin. The lignin-based BSCs were found to have compressive strength ranging from 1.6 - 8.1 MPa, which allows them to be implemented in non-structural construction applications. Ultimate compressive strength, density, and other parameters were measured, leading to the development of design relationships for lignin-based BSC. The design relationships presented in this study will help introduce lignin-based BSC as a sustainable form of construction.

Assessing the potential for upscaling the continuous production of lignin oils through reductive catalytic depolymerization

Lignin represents up to one third of lignocellulosic biomass and is a sustainable carbon source available at a sufficient scale to replace an impactful amount of fossil resources when converted into materials and chemicals. The molecular structure of lignin renders it ideal to obtain renewable aromatic building blocks for the polymer industry. Nevertheless, in polymeric form, lignin poses serious challenges for material applications and chemical conversion, namely poor solubility, and low reactivity. This problem can be circumvented by depolymerization of isolated lignins. To meet the demand for renewable aromatic building blocks, it is crucial to utilize technical lignin streams generated on large scale. This will eventually allow the development of continuous, high-throughput processes which are required for viable industrial-scale operations. Our work demonstrates for the first time that “technical grade” hydrolysis lignin from an operating biorefinery can be successfully subjected to continuous reductive catalytic depolymerization (RCD) in a packed bed reactor using a commercially available Pd/Al2O3 catalyst. The impact of catalyst amount, feed concentration (in methanol), and temperature with regards to process stability and product quality was investigated. The product was characterized by NMR, GPC, and GC-FID. Feed concentrations up to 7 wt% could be continuously processed for 77 h at 200 °C whereas at 225 °C, the operation time was restricted to 21 h. In all cases, a stable output was obtained over time in terms of molar mass, OH-group distributions, and monomer content. At 200 °C, carbon yields above 90 % of the soluble lignin fraction were feasible.

An oxidative depolymerized lignin treated by potassium ferrate and its use in preparation of epoxy resin

AbstractLignin, as an industrial by‐product, can be used as a phenolic substancen. In this study, enzymatic hydrolysis lignin (L) was treated with potassium ferrate and phenol respectively to obtain oxidized lignin (OL) and phenolated lignin (PL). Their phenolic hydroxyl content (PhOH) increased by 29.1% and 40.5%, respectively. Then four kinds of epoxy resins were prepared, namely lignin‐free epoxy resin (LFER), L epoxy resin (LER), PL epoxy resin (PLER), and OL epoxy resin (OLER). Gel permeation chromatography (GPC) and Fourier transform infrared analyses indicated that potassium ferrate oxidation could decline the molecular weight (Mw) and increase the PhOH of L. Mechanical properties test and dynamic mechanical analysis (DMA) results show that cured OLER (OLEN) has higher crosslinking density and better mechanical properties (shear strength increased by 14%, tensile strength increased by 15%) than cured LER (LEN). Thermogravimetric analysis results show that OLEN has better thermal stability than cured LFER (LFEN) and LEN. In addition, scanning electron microscopy images showed that the modified L had better compatibility. This study presents a novel approach for lignin oxidation.

Multispecies Trichoderma in Combination with Hydrolyzed Lignin Improve Tomato Growth, Yield, and Nutritional Quality of Fruits

The application of biological pesticides as alternatives to chemical phytosanitary products is a natural and innovative method to improve environmental protection and sustainable agricultural production. In this work, the compatibility between Trichoderma spp. and a commercial lignin extract was assessed in vitro and in vivo. The beneficial effects of lignin in combination with different Trichoderma consortia were evaluated in terms of improved growth and quantitative and qualitative tomato productivity. T. virens GV41 + T. asperellum + T. atroviride + lignin formulation was the most effective in growth promotion and increased root and stem dry weight compared to control (45.4 and 43.9%, respectively). This combination determined a 63% increase in tomato yield compared to the control, resulting in the best-performing treatment compared to each individual constituent. Consistent differences in terms of lycopene, GABA, ornithine, total, essential, and branched-chain amino acids were revealed in fruits from tomato plants treated with Trichoderma–lignin formulations (T. asperellum + T. virens GV41 + lignin) or with the microbial consortia (T. asperellum + T. virens GV41, T. atroviride + T. virens GV41). The developed bioformulations represent a sustainable biological strategy to increase yield and produce nutritional compound-enriched vegetables.

Enhanced solar interfacial evaporation through lignin-polyaniline composite coatings on Balsa wood substrates

Solar interfacial evaporation employing wood-derived substrates is increasingly acknowledged as a viable desalination and wastewater treatment technique. This study presents an optimized method that enhances the efficiency of solar interfacial evaporation by applying a coating of lignin-polyaniline composites (EHL-PANI) onto balsa wood substrates. Initial assessments involved comparing evaporators made from various kinds of wood, identifying balsa wood-based photothermal evaporators as the most effective, with an evaporation rate of 1.63 kg·m−2·h−1 and an efficiency of 72.7 %. Photothermal properties were further improved through the chemical oxidation of enzymatic hydrolysis lignin (EHL) with polyaniline, producing a composite with notably high dispersion stability and uniform particle distribution. This modification resulted in reduced particle size and enhanced stability of the polyaniline, which is crucial for boosting photothermal activity. Additionally, the EHL-PANI composites demonstrated exceptional light absorption, exceeding 95 %, and significant photothermal conversion efficiency across a broad wavelength range, attributable to polyaniline's broadband light absorption characteristics. A prototype evaporator, featuring the EHL-PANI coated on a balsa wood substrate, was constructed to assess performance, achieving a water evaporation rate of 2.10 kg·m−2·h−1 and an efficiency of 80.7 % under solar illumination of 1 kW·m−2.

Biological conversion of lignin-derived ferulic acid from wheat bran into vanillin

Lignin is a promising feedstock for producing vanillin, one of the most extensively used flavor enhancers. However, the biotransformation performance of lignin derivatives into vanillin is still unsatisfactory. In this study, an efficient conversion strategy of lignin into vanillin was established by employing engineered Saccharomyces cerevisiae as a whole-cell biocatalyst. Optimization of cell culture media and whole-cell bioconversion improved the production efficiency of vanillin. The vanillin titer reached 15.3 mM with a molar yield of 71 % in fed-batch fermentation mode, while incorporating in-situ product separation, demonstrated a remarkable 2.6-fold increase. The whole-cell bioconversion, coupled with in-situ separation, successfully converted real lignin hydrolysate into a record vanillin titer of 21.1 mM, equivalent to 1.8 mg of vanillin per gram of wheat bran biomass. The whole-cell bioconversion process integrated in-situ product separation, represents a sustainable approach for vanillin production and offers a promising pathway for lignin valorization.

Catalytic pyrolysis of hydrolyzed lignin using HZSM-5/MCM-41 supported transition-metal to produce monocyclic aromatic hydrocarbons

Hydrolyzed lignin (HL), one kind of organic solid wastes, comes from the production of hydrolysis of lignocellulosic biomass for high-value chemicals, unsuitable treatment of which not only meaning the waste of resources but also resulting environmental pollution. The pyrolysis of HL has the problem of high oxygen-containing compounds and low hydrocarbons in the products. The HZSM-5/MCM-41 (HM) meso-microporous composite catalyst, containing nickel and molybdenum, was synthesized through impregnation to enhance the production of monocyclic aromatic hydrocarbons (MAHs) during the in-situ catalytic pyrolysis of hydrolyzed lignin. Different transition metals loaded on composite molecular sieves were prepared for comparison. The relationship between catalyst structure and pyrolysis efficiency was studied based on characterization techniques including SEM, BET, and XRD. This study investigated the catalytic properties of modified composite molecular sieves with Ni and Mo at different loaded ratios on the pyrolysis of hydrolyzed lignin. Results indicated that HM loaded with different metals had different catalytic pyrolysis selectivity. The relative yield of MAHs on 3 %Ni-HM was the highest, at 27.78 %, while that of phenolic on 5 %Mo-HM was 51.02 %. Thus, by modifying the co-loading ratios between Ni and Mo, the combined catalytic pyrolysis of hydrolyzed lignin was performed, achieving a 39.24 % yield of MAHs on the catalyst Mo1Ni2-HM, markedly surpassing the 17.69 % yield from unaltered HZSM-5/MCM-41. In addition, the improvement of active sites was caused by transition metals loaded and the synergistic effect between bimetals enhanced the catalytic activity and stability. HZSM-5/MCM-41 loaded with metal oxides promoted the depolymerization of macromolecules in the intermediate products of pyrolysis, and thus improved the relative yield of MAHs among pyrolysis products of hydrolyzed lignin.

One-pot bioconversion of lignin to 4-vinylphenol derivatives

Lignin, the largest renewable aromatic resource in nature, is a promising feedstock to produce aromatic fine chemicals. The bioconversion of lignin into 4-vinylphenol derivatives (4VPs) is a sustainable route to promote both lignin valorization and bioeconomy. However, challenges such as heterologous lignin and an inefficient synthetic pathway for 4VPs restrict the bioconversion performance. In this work, microbial cell factories were designed to valorize lignin into 4VPs, emphasizing an atom-economic route. Rewriting endogenous pathways and heterogeneously expressing phenolic acid decarboxylases successfully produced 4VPs from lignin-derived aromatic precursors. Enzymatic kinetics revealed that the screened phenolic acid decarboxylases possessed outstanding catalytic activity against lignin derivatives. A biphasic glyceryl tributyrate/water system was developed for efficient in situ extraction of 4VPs, successfully removing the product-feedback inhibition effect. Accordingly, the microbial cell factory produced the record titers of 4-vinylphenol, 4-vinylguaiacol and 4-vinylsyringol at 235.3, 203.0 and 35.8 g/L, respectively, with the productivity of 3.0, 2.7, and 0.8 g/L/h. The microbial cell factory was further engineered to simultaneously convert three-type aromatic of lignin into 4VPs through a one-pot bioconversion. The microbial cell factory also exhibited the remarkable bioconversion capacity of actual lignin hydrolysate by producing 12.4 g/L and 2.3 g/L of 4-vinylphenol and 4-vinylguaiacol, respectively. The molecular mechanism suggested that corresponding polymers were successfully produced and displayed good thermal stability. Overall, the microbial cell factory demonstrated an impressive capacity to convert lignin derivatives and achieve record titers of 4VPs, showcasing its potential to revolutionize lignin valorization and the production of functional polystyrene materials.

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

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

Long-term mold resistance strategy of laccase-catalyzed eugenol-modified bamboo and its antimicrobial mechanism derived from lignin

Bamboo, which has excellent physical properties and environmental credentials, is widely used in the construction industry and furniture manufacturing. Bamboo is, however, susceptible to attack by molds and bacteria; protection by natural phenolic antimicrobial agents would be a green and environmentally friendly solution to this problem. The application of such protection has, so far, been hampered by poor stability and ease of volatilization of the antimicrobial agent. Here, an innovative strategy that uses the catalytic action of the laccase to chemically attach a natural antimicrobial agent, eugenol (EU), to bamboo, is described. This modification endows bamboo with both long-lasting and extensive mold resistance and antibacterial activity. Laccase-catalyzed covalent bonding of EU to bamboo reduces the volatilization rate of the EU from 1.72 % to 0.29 %. The outstanding mold resistance and antimicrobial activity of bamboo treated using this modified process is retained during a 50-day mold resistance test, with mold growth inhibited by as much as 87.5 %. The treated bamboo is also able to inhibit the growth of both Gram-positive and Gram-negative bacteria. The antimicrobial mechanism results shown that the bamboo lignin is the primary reaction site during laccase-catalyzed EU modification of bamboo, and the long-term mold resistance derived from modified lignin. Furthermore, we analyzed bacterial morphology through SEM, and the results demonstrated that modified enzymatic hydrolysis lignin (EHL) significantly disrupts bacterial morphology, including membrane invagination and collapse. This study provides a new direction for the green development of mold- and bacteria-resistant bamboo, which has potential for use in a wide range of application.

Investigation of the applicability of activated carbon obtained by thermochemical activation of hydrolytic lignin with sodium hydroxide as an electrode material of a supercapacitor

Investigation of the applicability of activated carbon obtained by thermochemical activation of hydrolytic lignin with sodium hydroxide as an electrode material of a supercapacitor

In Ukrainian

An important environmental problem is the removal of contaminants and the purification of domestic and industrial water from pollutants of various nature. There is a separate issue of cleaning the effluents of pharmaceutical enterprises. Various chemical and physical methods are used to solve these problems, such as settling, coagulation, filtration, and sorption techniques. Adsorption with using efficient and reusable adsorbents is the most effective and cheap. In recent years special attention has been paid to the use of sorption materials based on hydrolysis lignin, which has a high sorption activity in relation to ions of some heavy metals, dyes, organic compounds and pharmaceuticals. The use of lignin as an adsorbent simultaneously solves two problems: the disposal of paper production waste and the purification of sewage from various types of pollutants. The aim of this work was to study the sorption properties of hydroylysis lignin in aqueous solution in relation to some medical substances of different chemical nature, existing in solution in cationic, anionic or neutral forms. The point of zero charge of hydrolysis lignin was determined, which is equal to рНPZC = 4.95. The adsorption of rivanol, proflavin, doxorubicin, levofloxacin, furacilin, and salicylic acid by hydrolysis lignin was studied as dependence on the pH of the solutions and the concentration of adsorbates. It was found that adsorption largely depends on the structure of the pharmaceuticals and the pH values of the solutions. It is shown that the studied medical compounds, which exist in the solution in the form of cations, are adsorbed the best (rivanol, proflavin, doxorubicin). Adsorption of these substances occurs mainly due to electrostatic interaction with negatively charged surface groups. Adsorption of anionic form (salicylic acid) is the smallest and is observed only at quite low pH values. Levofloxacin is adsorbed mainly in the form of zwitter ions, and furacilin is in neutral form. The adsorption of these both compounds occupies an intermediate value of adsorption amount. The obtained adsorption isotherms are well lined up in Langmuir coordinates. Quantitative parameters of adsorption values - of maximum adsorption and equilibrium constants were calculated. Quite high values of these parameters indicate that hydrolysis lignin can be used as an adsorbent for the removal of these pharmaceuticals.

A synergistic approach for lignin biofuel production: Integrating non-catalytic solvolysis with catalytic product upgrading

Enzymatic hydrolysis lignin (EHL) is a large-scale industrial waste generated from the bio-ethanol production process. Its complex and heterogeneous nature as well as its low solubility in common solvents, has posed a persistent barrier to its effective utilization. Here, EHL was converted into biofuel through a two-step process, involving non-catalytic solvolysis followed by catalytic product upgrading. The non-catalytic solvolysis step achieved complete EHL liquefaction in a mixture of isopropanol and H2O without char formation. In this step, H2O disrupts the hydrogen bonds in EHL and isopropanol break π-π stacking interactions between the aromatic rings in EHL·H2O also enhances EHL depolymerization, while isopropanol, as a hydrogen donor solvent, provides hydrogen that stabilizes active intermediates. In the catalytic product upgrading step, the liquid product of the first step was transformed into biofuels rich in cycloalkanes, arenes and alkylphenols, with a total carbon yield of 45.6 %. Isopropanol-H2O reforming reactions provided hydrogen for the upgrading process, avoiding the introduction of H2. This work demonstrates an effective approach for converting EHL into biofuels.

Lignin-incorporated Co-MOFs-derived catalysts for selective hydrodeoxygenation of lignin-derived phenols into cyclohexanols

Lignin accounted for the second largest amount in biomass, and was regarded as an important carbon source and important renewable source for value-added chemicals. Herein, a series of lignin-derived carbon-based heterogeneous catalyst was synthesized through a simple hydrothermal method, using Co-MOFs as template. Lignin was introduced as a carbon material into MOF catalysts. Through some characterizations, it has been proven that lignin has been successfully introduced into MOF materials and significantly improved the catalyst performance. Then, lignin-MOF derived catalysts (Co/C-EL-X) were successfully introduced into the catalytic hydrodeoxygenation of lignin-derived phenols. The addition of enzymatic hydrolysis lignin (EL) in catalysts, calcination temperature and some other factors were investigated in detail, considering the catalytic performance during the HDO of vanillin and other typical lignin-derived phenols. Co/C-EL-0.5(500) exhibited the best catalytic performance for the conversion of different kinds of lignin-derived phenols to either 2-methoxy-4-methylphenol (MMP) or cyclohexanol. Under the optimal conditions of 240 °C, 0 MPa N2, and 2 h, the conversion rate of vanillin reached 100 %, and the yield of 4-methyl-2-methoxyphenol (MMP) was up to 92 %. Furthermore, vanillin could also be converted into 4-methylcyclohexanol (MCYL) by changing the initial nitrogen pressure. Also, Co/C-EL-0.5 (500) exhibited high activity for the conversion of other lignin-derived phenols into cyclohexanol (COL). This work provided a novel strategy for the catalytic valorization of lignin sources.

Mechanism of formation H2 and CH4 by hydrolysis and alcoholysis of lignin: A density functional theory study

Hydrolysis and alcoholysis are considered as viable routes for efficient degradation and recycling high-quality gas fuel of lignin. Mechanism of formation H2 and CH4 by hydrolysis and alcoholysis of various phenylic lignin model compounds were studied using density functional theory method at M06–2X/6–31++G(d,p) level. Formation H2 by eight hydrolysis reaction pathways and formation CH4 by eight alcoholysis reaction pathways were designed. The standard kinetic and thermodynamic parameters of hydrolysis and alcoholysis reaction pathways were calculated. The results show that energy barriers for hydrolysis of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) formaldehyde paths (about 270.0 kJ/mol) are higher than those for hydrolysis of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) acetaldehyde paths (about 250.0 kJ/mol). Thus, H2 is easily formed during the decomposition of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) acetaldehyde. The energy barriers for alcoholysis of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) formaldehyde paths (about 370.0 kJ/mol) are lower than those for alcoholysis of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) acetaldehyde paths (about 355.0 kJ/mol). Thus, CH4 is easily formed during the decomposition of phenyl (p-hydroxyphenyl, guaiacyl, and syringyl) acetaldehyde. In addition, temperature is the key factor in the lignin degradation process, the calculation results indicate the reaction rate increases with the increase of temperature, and the reaction in water molecular environment is better than that in methanol medium.

Experimental Combustion of Different Biomass Wastes, Coals and Two Fuel Mixtures on a Fire Bench

When designing settlements according to the “Green Building” principle, it is necessary to develop a heating system based on climatic conditions. For example, in areas with a sharply continental climate (cold and prolonged winters), it is sometimes necessary to use solid fuel boilers (in the absence of gas). However, to use these, it is necessary to use biomass or biomass-coal blends as fuel to increase their combustion heat. The addition of biomass waste to coal can be aimed at achieving various objectives: utilization of biomass waste; reduction of solid fossil fuel consumption; improvement of environmental performance at coal-fired boiler houses; improvement of the reactivity of coals or to improve the technical and economic performance of heat-generating plants due to the fact that biomass is a waste from various types of production, and its cost depends only on the distance of its transportation to the boiler house. In this work, combustion of various biomass wastes, including sewage sludge, was carried out on a fire bench emulating the operation of a boiler furnace. Fuel particles were ignited by convective heat transfer in a stream of hot air at a velocity of 5 m/s in the temperature range of 500–800 °C, and the experimental process was recorded on a high-speed, color video camera. The obtained values were compared with the characteristics of different coals used in thermal power generation (lignite and bituminous coal). The aim of the work is to determine the reactivity of various types of biomass, including fuel mixtures based on coal and food waste. The work presents the results of technical and elemental analysis of the researched fuels. Scanning electron microscopy was used to analyze the fuel particle surfaces for the presence of pores, cracks and channels. It was found that the lowest ignition delay is characteristic of cedar needles and hydrolyzed lignin; it is four times less than that of lignite coal and nine times less than that of bituminous coal. The addition of hydrolysis lignin to coal improves its combustion characteristics, while the addition of brewer’s spent grain, on the contrary, reduces it, increasing the ignition time delay due to the high moisture content of the fuel particles.

Funneling lignin hydrolysates into β-ketoadipic acid by engineered Pseudomonas putida KT2440

Bioconversion of lignin into value-added chemicals could promote lignin valorization and the lignin-based bioeconomy. The heterogeneity nature of lignin and the lack of efficient conversion pathways pose limitations on the efficiency of lignin conversion. In this study, Pseudomonas putida KT2440 was successfully engineered for converting lignin to β-ketoadipic acid, a C6 keto-diacid that functions as building block for high performance polymers. Blocking the degradation pathway of β-ketoadipic acid enabled its biosynthesis from both H- and G-type lignin-derived monomers. The aromatic hydroxylation and O-demethylation was identified as the rate-limiting step for producing β-ketoadipic acid from H- and G- type lignin-derived monomers, respectively. Overexpressing pobA and vanAB successfully vanished the accumulation of 4-hydroxybenzoic acid and vanillic acid within 36 h and 30 h, respectively. The beneficial gene operations were integrated into the chromosome to create the strain HE65. Employing this strain, fed-batch strategies were used to achieve a record β-ketoadipic acid production of 14.80 g/L from mixed lignin-derived aromatics in shake-flask experiments. Remarkably, the strain could also thrive in actual lignin hydrolysates from corn stover, yielding a record β-ketoadipic acid output of 2.48 g/L without the need for separation or detoxification processes. Overall, these results underscore the significant potential of engineering P. putida for converting lignin into β-ketoadipic acid, offering a promising pathway for feasible lignin valorization.

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%.

Sustainable waterborne polyurethane/lignin nanoparticles composites: Durability meets degradability

Optimizing the durability and degradability of polymers is essential for prolonging their useful life and minimizing their environmental footprint post-use, contributing to a sustainable world; however, durability in many cases conflicts with degradability. In this context, we developed lignin-based waterborne polyurethane (WPU) composites that bypass this dichotomy. Lignin nanoparticles (LNP), derived from enzymatic hydrolysis lignin (EHL), were synthesized using the anti-solvent method and incorporated into WPU emulsions through solution blending. The introduction of 5 wt% LNP notably improved the tensile strength of WPU composites, increasing it from 21.5 MPa to 29.7 MPa, a surge of up to 38 %. Moreover, 5 wt% of LNP significantly enhanced the durability of WPU by reducing creep strain (under a stress of 1 MPa for 3000 s) from 606 % to 70 % with an 88 % decrease, and by increasing molecular weight retention rate from 11 % to 87 % after 15 days of UV exposure. Concurrently, LNP notably accelerated the alkaline degradability of WPU/LNP composites, with weight loss rate increasing from 38 % to 92 % (a 142 % increase) and molecular weight loss from 17 % to 44 % (a 159 % increase), compared to pure WPU. The strategy employed in this study leverages the inherent properties of LNP to offer a promising approach to enhancing polymer sustainability, presenting an effective solution to the significant end-of-life challenge.