Lignin Fractions Research Articles

Tuning the antioxidant and antibacterial properties of lignin by physicochemical modification during sequential acid precipitation from Kraft black liquor

Turning lignin from black liquor waste into value-added bioactive agents is one of the possible routes for improving the sustainability and profitability of lignocellulosic industry. However, due to chemical and structural variability of lignin, it is necessary to isolate specific lignin fractions from black liquor with the purpose to achieve samples with unique chemical and structural characteristics and therefore, specific biological activities. In this study, poplar lignin fractions isolated from Kraft black liquor by sequential acid precipitation at pH´s 7.5, 5 and 2.5 (denoted as P-7.5, P-5 and P-2.5) were characterized according to their physicochemical, antioxidant and antibacterial properties. In general, lignin fractions displayed a wide elimination of lateral chains (aryl-β ether and C–C) and, therefore a high phenolic content and low molecular weight, as the pH sequential precipitation was decreased from 7.5 to 2.5. Moreover, thermal analysis revealed that the P-7.5 lignin fraction showed higher thermal stability than P-2.5 and P-5. In terms of antioxidant activity, the P-7.5 lignin fraction, with a higher S/G ratio and a less oxidized structure compared to P-5 and P-2.5, exhibited higher antioxidant activity. In addition, lower antibacterial effect was observed for all lignin fractions against Escherichia coli compared to that obtained against Staphylococcus aureus. Among them, the P-2.5 and P-5 fractions, with higher phenolic content and lower molecular weight values than P-7.5, showed a greater antibacterial effect against S. aureus.

Lignin Nanofiber Flexible Carbon Aerogels for Self-Standing Supercapacitors.

Renewable feedstocks are sought for clean technology applications, including energy storage applications. In this study, LignoForce™ lignin, a biobased aromatic polymer commercially isolated from wood, was fractioned into two parts using acetone, and the resulting lignin fractions had distinct thermo-rheological behavior. These two fractionated lignins were combined in various ratios and transformed into nanofibers by electrospinning. Subsequently, electrospun fiber materials were disrupted by agitating the mats in water, and the materials were transformed into ultralight 3D aerogels through lyophilization and post-process controlled heating. Using only this combination of two fractions, the morphology of lignin nanofibers was tailored by heat treatment, resulting in lignin aerogels with high flexibility and significant shape recovery properties. Various microscale structures of lignin fibers impacted the resulting physical properties of the elastic aerogel materials, such as resilience, compressive strength, and electrical conductivity for the corresponding carbonized samples. By exploiting lignin's sensitivity to heat and tailoring the thermal properties of the lignin through fractionation, the work provided an interesting path to form robust lignin-derived functional materials without any toxic chemical additives and significant ability to serve as free-standing electrodes with specific capacitance values better than some graphene-based supercapacitors.

On the fractionation of lignin oligomers by stepwise gradient reversed-phase liquid chromatography

With the increased interest in lignin valorization, the analytical challenge to separate a complex mixture of a vast number of phenolics has made chromatography an indispensable step in lignin analysis. High-resolution separations, such as gas chromatography, reversed-phase liquid chromatography and supercritical fluid chromatography have typically been targeting low-molecular-weight compounds, while larger lignin oligomers have received less attention. These compounds have proven to be difficult to separate due to the inherent complexity of the high-molecular-weight fraction of lignins, in fact, even high-resolving linear reversed-phase gradients elute them as one wide zone. To tackle this, in this study we show that a crude fractionation of lignin oligomers can be achieved by applying stepwise reversed-phase gradients. A commonly employed reversed-phase system with water:acetonitrile mobile phase is evaluated for this task. Special attention was devoted to uncovering the molecular level explanation of the retention phenomenon. Our results indicate that separation is mainly governed by reversed-phase retention phenomena without any major exclusion or viscosity-related effects, shown by great fits to linear retention models (R2avg=0.9599 for five different oligomers) and apparent differences in retentivity between different stationary phases. The influence of the gradient shape was demonstrated by the comparison of stepwise gradients with different number and frequency of steps, leading to the conclusion that gradients with a low number of steps yield fewer, but better resolved fractions, while finer multi-step gradients can be used to distinguish more fractions.

Enhancing the biorefinery of brewery spent grain by deep eutectic solvent pretreatment: Optimisation of polysaccharide enrichment through a response surface methodology

One of the main challenges in biorefinery is the efficient fractionation and use of lignocellulosic biomass. In this sense, pretreatment with deep eutectic solvents (DES) is highlighted as a clean and effective separation method, due to its selective solubilisation of hemicellulose and lignin fractions while preserving cellulose. This study presents a process of the enrichment of polysaccharide content and the improvement of enzymatic digestibility using choline chloride (ChCl) and lactic acid (LA) or glycerol (Gly) in brewery spent grain (BSG) pretreatment. Additionally, it describes how improvements can be made in obtaining polysaccharide-rich material through a response surface methodology, this by means of analysing the operational conditions (temperature, reaction time, and molar ratio) using ChCl:LA. The optimised operational conditions (130 °C, 90 min, and 1:8 mol/mol) generate a 75 % enrichment of polysaccharide fraction and the remotion of 77.13 %, 50.70 %, and 100 % of acid-soluble lignin, xylan, and arabinan, respectively. Moreover, the process enhances the saccharification of glucan and xylan to almost 70 % using Cellic CTec2, and to 80 % of glucan and 40 % of xylan using A. niger CECT 2700 enzymatic extract. This constitutes a promising approach to the fractioning of cellulose and lignin from BSG through DES pretreatment, which is unfeasible using traditional pretreatment methods.

Optimizing corncob pretreatment with eco-friendly deep eutectic solvents to enhance lignin extraction and cellulose-to-glucose conversion

Deep eutectic solvents (DES) are an eco-friendly, cost-effective alternative to traditional ionic liquids for biomass pretreatment, with unique characteristics encompassed by hydrogen bond donor (HBD), the molar ratio of hydrogen bond acceptor (HBA) to HBD, temperature, and time affecting efficiency. Despite its potential, a comprehensive study exploring the interplay of these factors is limited. This study explores the optimization of pretreatment variables using choline chloride/lactic acid (1:5) via the response surface method (RSM). It aims to evaluate the effects of time and temperature on lignin extraction, cellulose-to-glucose conversion, and hemicellulose removal. Employing a 22 central composite design with temperature (80–140 °C) and time (2–6 h) as variables, optimal conditions were 123 °C for 6 h. Results include 90.08±1.42 % lignin extraction, 68.77±6.9 % cellulose-to-glucose conversion, and 77.34±0.85 % hemicellulose removal, with 52.52±8.07 % lignin recovery. The fractions of pretreated CC and lignin recovered in the optimal condition found were characterized by X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR), 1H, 13C, 2D-HSQC NMR spectroscopy, Thermogravimetric analysis (TGA/DTG), Gel Permeation Chromatography (GPC) to elucidate chemical characteristics of the materials obtained and facilitate downstream valorization. High efficiency was achieved in lignin extraction and cellulose conversion, and addressing solvent viscosity and DES recycling will further enhance the potential for industrial scalability.

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.

Optimizing Planting Density, Irrigation, and Nitrogen Application Can Improve Rapeseed Yield in Xinjiang’s Aksu by Reducing the Lodging Rate

This study aimed to investigate the effects of planting density, irrigation volume, and nitrogen application on the resistance of rapeseed to lodging and yield and to provide technical support for achieving high yield and lodging resistance. We employed an L9 (34) orthogonal array, different planting densities, irrigation levels, and nitrogen applications to investigate their impact on rapeseed lodging and yield. The results showed the following: (1) Irrigation had the greatest effect on rapeseed lodging. This effect was most pronounced for the combination (A3B3C2), which exhibited the most severe lodging phenomenon (90%). Planting density had the greatest effect on yield, and the optimal combination was A2B2C3, which reached 3744 kg/hm2 in 2023 and 3420 kg/hm2 in 2024. (2) The agronomic practices increased the content of lignin, cellulose, hemicellulose, crude fiber, pectin, and soluble sugar fractions in the stalks by enhancing their flexural, puncture, and stress resistance. This led to the highest yield while reducing the rate of lodging. This emphasizes the importance of agricultural practices for rapeseed lodging and yield, providing critical insights into rapeseed cultivation in the Aksu region of Xinjiang.

Fractionation of lignin and fermentable sugars from wheat straw using an alkaline hydrogen peroxide/pentanol biphasic pretreatment

To breakthrough the delignification saturation point (DSP) of alkaline hydrogen peroxide (AHP) pretreatment, a biphasic AHP/pentanol (AHPP) pretreatment was proposed in this work. The temperature and H2O2 concentration were evaluated. Under the optimal conditions (110 °C, 2 h, 4 % H2O2), 70.73 % of lignin was removed, which was increased by 11.65 % than the traditional AHP pretreatment, indicating successful overcoming of the DSP by adding pentanol. 85.74 % and 88.62 % of glucan and xylan digestibility were achieved, respectively, which increased by 7.41 % and 5.87 % as compared to AHP pretreatment. Furthermore, the lignin extracted from the organic phase accounted for 38.51 % of the delignification, and it had a low molecular weight, effectively preserving the β-O-4 bonds. Finally, satisfied pentanol recovery (77.91 %) and delignification (57.19 %) along with excellent glucan (76.11 %) and xylan (77.52 %) digestibility were reached after fourth recycling of AHPP pretreatment. Therefore, AHPP pretreatment was a promising method for biomass valorization within biorefinery concept.

Green synthesis of graphene oxide and magnetite nanoparticles and their arsenic removal efficiency from arsenic contaminated soil

Graphene-based nanomaterials have been proved to be robust sorbents for efficient removal of environmental contaminants including arsenic (As). Biobased graphene oxide (bGO-P) derived from sugarcane bagasse via pyrolysis, GO-C via chemical exfoliation, and magnetite nanoparticles (FeNPs) via green approach using Azadirachta indica leaf extract were synthesized and characterized by Ultraviolet-Visible Spectrophotometer (UV-vis.), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), mean particle size and Scanning electron microscopy (SEM) along with Energy dispersive spectroscopy (EDX) analysis. Compared to cellulose and hemicellulose, the lignin fraction was less in the precursor material. The GOC, bGO-P and FeNPs displayed maximum absorption at 230, 236, and 374 nm, respectively. FTIR spectrum showed different functional groups (C-OH, C-O-C, COOH and O-H) modifying the surfaces of synthesized materials. Graphene based nanomaterials showed clustered dense flakes of GO-C and thin transparent flakes of bGO-P. Elemental composition by EDX analysis of GO-C (71.26% C and 27.36% O), bGO-P (74.54% C and 24.61% O) and FeNPs (55.61% Fe, 4.1% C and 35.72% O) confirmed the presence of carbon, oxygen, and iron in synthesized nanomaterials. Sorption study was conducted with soil amended with different doses of synthesized nanomaterials (10, 50 and 250 mg) and exposed to 100, 300 and 500 ppm of As. Arsenic concentrations were estimated by colorimetry and atomic absorption spectroscopy (AAS). GO-C, bGO-P, and FeNPs showed substantial As removal efficiency i.e., 81 to 99.3%, 65 to 98.8% and 73.1–89.9%, respectively. Green synthesis of bGO-P and magnetite nanoparticles removed substantial amounts of As compared to GO-C and can be effectively deployed for As removal or immobilization. Higher and medium sorbent doses (250 and 50 mg) exhibited greater As removal and data was best fitted for Freundlich isotherm evidencing favorable sorption. Nevertheless, at low sorbent doses, data was best fitted for both models. Newly synthesized nanomaterials emerged as promising materials for As removal strategy for soil nano-remediation and can be effectively deployed in As contaminated soils.

Streamlined fractionation for recovery of high-yield xylo-oligosaccharides, pure lignin and ethanol from poplar using short-chain organic acid/pentanol biphasic system

Biphasic pretreatment offers a sustainable method by integrating the fractionation of hemicellulose, lignin, and cellulose into a single process, thereby enhancing biomass resource utilization while reducing environmental impact. However, this process faces the challenge of diverse hemicellulose products with low added value. This study employed organic acid-catalyzed water/pentanol biphasic pretreatment to selectively convert hemicellulose into xylooligosaccharides (XOS), while simultaneously separating lignin and cellulose. Both the organic acids and pentanol used are biodegradable and compatible. The lactic acid (LA)/pentanol biphasic system was particularly effective for XOS production and lignin removal, attributed to the high acidity of LA and its relatively low partition coefficients in the water/pentanol system, crucial factors influencing hemicellulose and lignin separation efficiency. The XOS yields reached 46.9 %, while the lignin removal rate was 74.6 %. Additionally, LA/pentanol pretreatment significantly enhanced cellulose digestibility, demonstrated by an ethanol production of 54.1 g/L during simultaneous saccharification fermentation at 15 % solids loading. The recovered lignin from the organic phase retained the structural characteristics of native lignin. It also had a low molecular weight and abundant phenolic hydroxyl groups, indicating its suitability for further valorization. Pentanol maintained its performance after four cycles of reuse, demonstrating the stability and reusability of the solvent system. This study highlighted the potential of the LA/pentanol biphasic system for simultaneous hemicellulose conversion and lignin isolation, offering a simplified and sustainable one-step valorization route for biomass.

Understanding and enhancing the phase stability of fast pyrolysis oils through ternary phase diagrams

Fast pyrolysis oils (FPOs), derived from various biomass feedstocks, hold promise as carbon–neutral fuels. However, their industrial use is hindered due to phase separations during storage, transportation and co-processing, with limited understanding of the root causes that drive this phenomenon. This study aims to elucidate the kinetic stability of FPO by developing ternary phase diagrams and exploring the effects of the temperature and addition of organic solvents on the aging. The phase stability of FPO was found to be determined by the fraction of pyrolytic lignin (PL), mixed solvent (MS), and water. Even at 25 °C, phase separations could consistently occur when the PL content exceeded 56 wt% or the MS content fell below 28 wt%. Heating the FPO to 50 °C–80 °C led to a decrease in the water-soluble content and an increase in the water-insoluble content, while the water content remained relatively unchanged, indicating the transition of the water-soluble content to water-insoluble content was closely related to FPO phase separation during aging at elevated temperatures. Moreover, the solvents could slow the aging of the FPO in the order of 2-propanol > ethanol > methanol > ethylene glycol > glycerol. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR-spectroscopy) analysis further revealed changes in both the chemical compositions and polymerizations during aging, in which alcohols were identified as effective inhibiters to slow the aging. These new findings provide promising pathways to controlling the FPO phase stability through solvent selections and will advance the adoptions of FPOs.

Delignification of Olive Tree Pruning Using a Ternary Eutectic Solvent for Enhanced Saccharification and Isolation of a Unique Lignin Fraction

Delignification of Olive Tree Pruning Using a Ternary Eutectic Solvent for Enhanced Saccharification and Isolation of a Unique Lignin Fraction

Simultaneously reducing methane emissions and arsenic mobility by birnessite in flooded paddy soil: Overlooked key role of organic polymerisation

Flooding of paddy fields enhances methane (CH4) emissions and arsenic (As) mobilisation, which are crucial issues for agricultural greenhouse gas emissions and food safety. Birnessite (δ-MnO2) is a common natural oxidant and scavenger for heavy metals. In this study, birnessite was applied to As-contaminated paddy soil. The capacity for simultaneously alleviating CH4 emissions and As mobility was explored. Soil microcosm incubation results indicated that birnessite addition simultaneously reduced CH4 emissions by 47 %–54 % and As release by 38 %–85 %. The addition of birnessite decreased the dissolved organic carbon (DOC) contents and altered its chemical properties. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) results showed that birnessite reduced the labile fractions of proteins, carbohydrates, lignins, tannins, and unsaturated hydrocarbons, however, increased the abundance of condensed aromatic structures, suggesting the polymerisation of dissolved organic matter (DOM) by birnessite. The degradation of labile fractions and the polymerisation of DOM resulted in an inventory of recalcitrant DOM, which is difficult for microbes to metabolise, thus inhibiting methanogenesis. In contrast, birnessite addition increased CH4 oxidation, as the particulate methane monooxygenase (pmoA) gene abundance increased by 30 %. The enhanced polymerisation of DOM by birnessite also increased As complexation with organics, leading to the transfer of As to the organic bound phase. In addition, the decrease in ferrous ion [Fe(II)] concentrations with birnessite indicated that the reductive dissolution of Fe oxides was suppressed, which limited the release of arsenite [As(III)] under reducing conditions. Furthermore, birnessite decreased As methylation and shaped the soil microbial community structure by enriching the metal-reducing bacterium Bacillus. Overall, our results provide a promising method to suppress greenhouse gas emissions and the risk of As contamination in paddy soils, although further studies are needed to verify its efficacy and effectiveness under field conditions.

Factors influencing mangrove carbon storage and its response to environmental stress

Mangrove forests serve as significant carbon sinks and play a crucial role in mitigating climate change. Currently, the response of mangroves to intensified climate change and human activities, and the factors that influence the magnitude of carbon storage in their sediments remain uncertain. To address these questions, two sediment cores were collected from the mangrove reserve in Pearl Bay, Guangxi, China. The activity of 210Pb in the sediment, grain size, bulk elemental composition, stable carbon isotopes, lignin, and different sediment organic matter (OM) fractions were investigated to determine the local mangrove’s response to climate change and human activities, as well as the factors influencing its carbon storage. The results showed mangrove forests with lower tidal ranges, slower sedimentation rates, and where OM predominantly originated locally tend to have larger carbon stocks. The mangrove OM (MOM) decreased progressively from the bottom to the top of the cores, indicating that the mangroves in Pearl Bay have possibly undergone degradation, which was further substantiated by the decrease in lignin content. Based on these results, the entire cores were divided into two stages: stable stage 1 (1963–2001) and degradation stage 2 (2001–2020). The cause of the mangrove degradation is likely due to the impact of human activities; however, these impacts are anticipated to gradually lessen in the future due to mangrove protection policies. Our results indicate that lignin can track and predict mangrove growth trends and provide guidance for the sustainable management of mangrove ecosystems.

Efficient binary diol-based deep eutectic solvent pretreatment for enhancing enzymatic saccharification and lignin fractionation from eucalyptus

An innovative binary biol-based deep eutectic solvent (DES), specifically ethylamine hydrochloride-ethylene glycol (EaCl-EG), was developed for efficient pretreatment of eucalyptus biomass. This DES exhibited superior performance in achieving high delignification (85.0%) and xylan removal (80.0%), while preserving a significant amount of cellulose (94.5%) compared to choline chloride-based DES. Notably, the pretreated eucalyptus residues showed a remarkable glucose yield of over 92.5%, representing a substantial enhancement of up to 15 times compared to untreated eucalyptus. Furthermore, the pretreated liquor yielded high-purity lignin with a yield of 97.8%, characterized by well-preserved β-O-4 structure and nanoscale dimensions. These lignin nanoparticles (LNPs) were subsequently self-assembled into lignin nanobottles (LNBs), adding further value to the pretreatment process. The proposed novel binary EaCl-EG DES presented great potential as an efficient pretreatment solvent for future biomass fractionation processes.

3D printing of lignin-based supramolecular topological shape-morphing architectures with high strength, toughness, resolution, and fatigue resistance

The design and fabrication of customized and sustainable elastomers with supramolecular frameworks remain a central focus of scientific research. 3D printing represents an advanced manufacturing technology that has garnered significant attention. Lignin, a naturally abundant polymer, fits well with 3D printing due to its unique aromatic-rich structures that can provide rigidity and structural support. However, challenges persist in developing UV-curable lignin-based inks and fabricating high-strength lignin-based composite hydrogels with tailored shapes and structures through vat photopolymerization (VPP) printing techniques, largely due to lignin’s inherent heterogeneity, fragility, and poor fluidity. Here, we successfully developed a unique lignin-based photosensitive macromonomer resin tailored for VPP 3D printing. Using an ethanol/water fractionation process, heterogeneous lignosulfonate (LS), a by-product of the pulp and paper industry, was treated to isolate highly reactive lignin fractions rich in phenolic hydroxyl and sulfonic groups. These fractions were then chemically modified to synthesize a lignin-based macromonomer known as urethane acrylated lignosulfonate (UALS). The resulting lignin-based macromonomer (15–35 wt%) exhibits excellent compatibility with photosensitive resin formulations, enabling effective VPP 3D printing. The 3D-printed lignin-based supramolecular composite hydrogels exhibit high strength (tensile strength of ∼2.12 MPa, an elongation at break of ∼220.13 %), high resolution, fatigue resistance (up to 10000 cycles), and moisture-induced responsive behavior. The development of 3D-printed lignin-based supramolecular elastomers with defined shapes and patterned structures significantly advances the discovery of robust and environmentally sustainable soft materials with potential applications in soft robotics and tissue engineering.

Optimization of Cellulose Recovery Using Deep Eutectic Solvent Fractionation: A Response Surface Method Approach

Lignocellulosic biomass is a crucial renewable energy source for producing biofuels and valuable compounds, making it an attractive alternative to fossil resources. In this study, an environmentally friendly method was developed for cellulose fractionation from sugarcane bagasse using deep eutectic solvents (DESs), focusing on achieving high cellulose purity and specific physicochemical properties. The effects of different parameters were investigated by comparing four DESs: choline chloride–lactic acid (ChCl-LA), choline chloride–glycerol (ChCl-G), choline chloride–urea (ChCl-U), and choline chloride–polyalcohol (ChCl-P), under various reaction temperatures and times. The fractionation process was conducted under standard conditions at a temperature of 100 °C for 120 min with a 1:1 molar ratio. The results indicated that all DESs produced comparable cellulose recovery, ranging from 91.83% to 97.07%. A relatively high cellulose recovery was observed in the presence of ChCl-LA, at 95.47%. In addition, ChCl-LA demonstrated the highest efficiency in removing hemicellulose and lignin, at 95.36% and 93.38%, respectively, and high recovery yields of 70.45% for hemicellulose, and 70.66% for the lignin fraction. The fractionation conditions were further optimized using response surface methodology (RSM), achieving a ChCl-LA ratio of 1:2 v/v at 120 °C for 120 min. This resulted in impressive yields: 97.86% cellulose recovery, 96.50% hemicellulose removal, 74.40% hemicellulose recovery, 77.3% lignin recovery, and 71.5% lignin yield from sugarcane bagasse. These results closely match the predicted values, emphasizing the effectiveness of the process and its potential for economic application in lignocellulosic biorefinery operations.

Assessment of Accelerated Aging Effect of Bio-Oil Fractions Utilizing Ultrahigh-Resolution Mass Spectrometry and k-Means Clustering of van Krevelen Compositional Space.

Bio-oils contain a substantial number of highly oxygenated hydrocarbons, which often exhibit low thermal stability during storage, handling, and refining. The primary objectives of this study are to characterize the hydroxyl group in bio-oil fractions and to investigate the relationship between the type of hydroxyl group and accelerated aging behavior. A bio-oil was fractionated into five solubility-based fractions, classified in two main groups: water-soluble and water-insoluble fractions. These fractions were then subjected to chemoselective reactions to tag molecules containing hydroxyl groups and analyzed by negative-ion electrospray ionization 21 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The fractions were also subjected to accelerated aging experiments and characterized by FT-ICR MS and bulk viscosity measurements. Extracting insightful information from ultrahigh-resolution data to aid in predicting upgrading methodologies and instability behaviors of bio-oils is challenging due to the complexity of the data. To address this, an unsupervised learning technique, k-means clustering analysis, was used to semiquantify molecular compositions with a close Euclidean distance within the (O/C, H/C) chemical space. The combination of k-means analysis with findings from chemoselective reactions allowed the distinctive hydroxyl functionalities across the samples to be inferred. Our results indicate that the hexane-soluble fraction contained numerous molecules containing primary and secondary alcohols, while the water-soluble fraction displayed diverse groups of oxygenated compounds, clustered near to carbohydrate-like and pyrolytic humin-like materials. Despite its high oxygen content, the water-soluble fraction showed minimal changes in viscosity during aging. In contrast, a significant increase in viscosity was observed in the water-insoluble materials, specifically, the low- and high-molecular-weight lignin fractions (LMWL and HMWL, respectively). Among these two fractions, the HMWL exhibited the highest increase in viscosity after only 4 h of accelerated aging. Our results indicate that this aging behavior is attributed to an increased number of molecular compositions containing phenolic groups. Thus, the chemical compositions within the HMWL are the major contributors to the viscosity changes in the bio-oil under accelerated aging conditions. This highlights the crucial role of oxygen functionality in bio-oil aging, suggesting that a high oxygen content alone does not necessarily correlate with an increase of viscosity. Unlike other bio-oil categorization methods based on constrained molecule locations within the van Krevelen compositional space, k-means clustering can identify patterns within ultrahigh-resolution data inherent to the unique chemical fingerprint of each sample.

From Field to Pharmacy: Isolation, Characterization and Tableting Behaviour of Microcrystalline Cellulose from Wheat and Corn Harvest Residues.

A lack of strategies for the utilization of harvest residues (HRs) has led to serious environmental problems due to an accumulation of these residues or their burning in the field. In this study, wheat and corn HRs were used as feedstock for the production of microcrystalline cellulose (MCC) by treatment with 2-8% sodium hydroxide, 10% hydrogen peroxide and further hydrolysis with 1-2 M hydrochloric acid. The changes in the FT-IR spectra and PXRD diffractograms after chemical treatment confirmed the removal of most of the lignin, hemicellulose and amorphous fraction of cellulose. A higher degree of crystallinity was observed for MCC obtained from corn HRs, which was attributed to a more efficient removal of lignin and hemicellulose by a higher sodium hydroxide concentration, which facilitates the dissolution of amorphous cellulose during acid hydrolysis. MCC obtained from HRs exhibited lower bulk density and poorer flow properties but similar or better tableting properties compared to commercial MCC (CeolusTM PH101). The lower ejection and detachment stress suggests that MCC isolated from HRs requires less lubricant compared to commercial MCC. This study showed that MCC isolated from wheat and corn HRs exhibits comparable tableting behaviour like commercial sample, further supporting this type of agricultural waste utilization.

DELIGNIFICATION OF OIL PALM EMPTY FRUIT BUNCHES USING DEEP EUTECTIC SOLVENT IN PRESSURIZED REACTOR

Although lignin from oil palm empty fruit bunches (OPEFB) is a sustainable bioresource with several value-added uses, it is still difficult to extract lignin from lignocellulosic biomass economically. Lignin fractions are required for high-value applications and subsequently increase the feasibility of lignocellulosic biorefineries. Besides, the remaining cellulose could be further valorized into various chemical products. In this study, the delignification efficiency of OPEFB under inert and pressurized conditions has been studied as an effective pretreatment method for OPEFB. The optimal conditions of the high-pressure reactor to remove lignin from OPEFB were determined to be 80 °C at 30 bars with the presence of deep eutectic solvents (DES). It was identified that pressure affects the removal of lignin with the least amount of structural breakdown and the digestibility of cellulose. The effective removal of lignin from the OPEFB was established under mild conditions employing an inert nitrogen gas pressurized system. This work selectively removes lignin from the OPEFB of palm oil biomass plants using DES under mild extraction conditions. Solid residues were characterized by using FTIR, SEM, TGA, and XRD to investigate fractions under various reaction conditions, such as removal temperature, time, and pressure. The thermal stability of lignin was determined by TGA. In this study, 36.68% of lignin was removed under optimum pressure conditions at the lowest process temperature of 80 °C to determine how these factors influence the efficiency of lignin extraction in a high-pressure reactor.