Search Results (38)

Lignocellulose is the most abundant renewable resource in nature, providing a large supply of lignin. The efficient separation and utilization of lignin from lignocellulose can help alleviate the current shortage of fossil fuels. Ionic liquids, as green solvents, have been widely applied in the field of biorefining. However, most research has focused on the extraction and purification of cellulose, while lignin is often treated as a by-product. The high-value utilization of lignin has currently emerged as a hot topic. This review summarizes recent advances in the extraction of lignin from lignocellulose using ionic liquids and the mechanisms of lignin extraction. Additionally, it briefly discusses the applications of ionic liquids in the high-value utilization of lignin, including lignin depolymerization, modification, the preparation of lignin-based functional materials, and biofuels. This review aims to provide ideas for the extraction and high-value utilization of lignin through ionic liquids. Full article

Various pretreatment methods, often employed in wood biorefineries, aim to disrupt the wood architecture, thereby enhancing the efficiency of hemicellulose extraction for increasing the production of bio-ethanol, bio-gas, and bio-oil, as well as improving the pulping process. Pretreatment for the pulping process has advantages such as enhanced yield in biorefined products and reducing chemicals and energy consumption. This study examined the effect of an alkaline hydrolysis of birch sawdust on the chemical composition, aggregation ability, and surface activity of soda lignin obtained by soda pulping. The alkaline hydrolysis of birch sawdust led to a remarkable removal of hemicellulose and reduced its mechanical strength. The resorption of lignin fragments on the lignocellulosic matrix during the hydrolysis was observed. The soda pulping of the original and the treated sawdust was carried out under laboratory conditions at 165 °C for 90 min, using 4.5% sodium hydroxide. A higher yield of soda lignin and pulp was obtained from the treated sawdust. The reduced content of acidic and methoxyl groups in the chemical composition of the soda lignin from the hydrolyzed sawdust was explained by the predominance of polycondensation reactions in forming its primary structure. The changes in size and zeta potential values of the formed lignin particles, as well as in the modality of the size distribution with decreasing pH, were studied. The early-proposed suggestion about the existence of structural complementarity in the formation of the ordered lignin supermolecular structures has been testified. The higher surface activity at the air–water interface for the soda lignin extracted from the hydrolyzed sawdust, compared to the lignin from the original residue, was mainly attributed to a lower content of the acidic groups in its chemical composition, shifting the hydrophilic–hydrophobic balance of its structure toward hydrophobicity. Full article

Lignocellulosic biomass is currently widely used in many biorefining processes. The full exploitation of biomass from uncultivated or even marginal lands for the production of biobased chemicals has deserved huge attention in the last few years. Among the sustainable biomass-based value chains, cardoon crops could be a feedstock for biorefineries as they can grow on marginal lands and be used as raw material for multipurpose exploitation, including seeds, roots, and epigeous lignocellulosic solid residue. This work focused on the technical analysis of a novel integrated flowsheet for the exploitation of the lignocellulosic fraction through the assessment of thermochemical, biochemical, and extractive technologies and processes. In particular, high-yield thermochemical processes (gasification), innovative biotechnological processes (syngas fermentation to ethanol), and extractive/catalyzed processes for the valorization of cardoon roots to FDCA and residual solid biomass were modeled and simulated. Inulin conversion to 2,5-Furandicarboxylic acid was the main conversion route taken into consideration. Finally, the novel process flowsheet, treating 130,000 t/y of residual biomass and integrating all proposed technologies, was modeled and assessed using process simulation tools to achieve overall mass and energy balances for comparison with alternative options. The results indicated that cardoon biorefining through the proposed flowsheet can produce, per 1000 tons of input dry biomass, 211 kg of 2,5-Furandicarboxylic acid and 140 kg of ethanol through biomass gasification followed by syngas fermentation. Furthermore, a pre-feasibility analysis was conducted, revealing significant and potentially disruptive results in terms of environmental impact (with 40 kt_CO2eq saved) and economic feasibility (with an annual gross profit of EUR 30 M/y). Full article

N,N′-Dialkylimidazolium-based ionic liquids are capable of completely dissolving lignocellulosic biomass at elevated temperatures and are considered as promising green solvents for future biorefining technologies. However, the obtained ionic liquid lignin preparations may contain up to several percent nitrogen. This indicates strong interactions between the biopolymer and the IL cation, the nature of which has not yet been clarified. The present study investigates mechanisms and pathways of the formation of nitrogen-containing lignin compounds. To achieve this goal, eight monomeric lignin-related phenols bearing different functional groups (ketone, aldehyde, hydroxyl, carbon–carbon double bonds) were treated with 1-butyl-3-methylimidazolium acetate (BmimOAc) under typical conditions of IL-assisted lignocellulose fractionation (80–150 °C). A number of the resulting products were tentatively identified, for all the studied model compounds, by two-dimensional NMR spectroscopy and high-performance liquid chromatography—high-resolution mass spectrometry. They all possess covalently bonded Bmim residues and occur through the nucleophilic addition of an N-heterocyclic carbene (deprotonated Bmim cation) to electron-deficient groups. The reactivity of lignin functional groups in their interaction with Bmim is greatly affected by the temperature and dissolved oxygen. IL’s thermal degradation products act as additional reactive species toward lignin, further complicating the range of products formed. The obtained results made it possible to answer the question posed in this article’s title and to assert that N,N′-dialkylimidazolium-based ILs act as active reagents with respect to lignin during the dissolution of lignocellulose. Full article

The hydrolysis and biotransformation of lignocellulose, i.e., biorefinery, can provide human beings with biofuels, bio-based chemicals, and materials, and is an important technology to solve the fossil energy crisis and promote global sustainable development. Biorefinery involves steps such as pretreatment, saccharification, and fermentation, and researchers have developed a variety of biorefinery strategies to optimize the process and reduce process costs in recent years. Lignocellulosic hydrolysates are platforms that connect the saccharification process and downstream fermentation. The hydrolysate composition is closely related to biomass raw materials, the pretreatment process, and the choice of biorefining strategies, and provides not only nutrients but also possible inhibitors for downstream fermentation. In this review, we summarized the effects of each stage of lignocellulosic biorefinery on nutrients and possible inhibitors, analyzed the huge differences in nutrient retention and inhibitor generation among various biorefinery strategies, and emphasized that all steps in lignocellulose biorefinery need to be considered comprehensively to achieve maximum nutrient retention and optimal control of inhibitors at low cost, to provide a reference for the development of biomass energy and chemicals. Full article

The degradation of the complex structure of lignocellulosic biomass is important for its further biorefinery to value-added bioproducts. The use of effective fungal species for the optimised degradation of biomass can promote the effectiveness of the biorefinery of such raw material. In this study, the optimisation of processing parameters (temperature, time, and s/w ratio) for cellulase activity and reducing sugar (RS) production through the hydrolysis of sugar beet pulp (SBP) by edible filamentous fungi of Aspergillus, Fusarium, Botrytis, Penicillium, Rhizopus, and Verticillium spp. was performed. The production of RS was analysed at various solid/water (s/w) ratios (1:10–1:20), different incubation temperatures (20–35 °C), and processing times (60–168 h). The Aspergillus niger CCF 3264 and Penicillium oxalicum CCF 3438 strains showed the most effective carboxymethyl cellulose (CMC) degrading activity and also sugar recovery (15.9–44.8%) from SBP biomass in the one-factor experiments. Mathematical data evaluation indicated that the highest RS concentration (39.15 g/100 g d.w.) and cellulolytic activity (6.67 U/g d.w.) could be achieved using A. niger CCF 3264 for the degradation of SBP at 26 °C temperature with 136 h of processing time and a 1:15 solid/water ratio. This study demonstrates the potential of fungal degradation to be used for SBP biorefining. Full article

This study presents a novel approach for biorefining oat husks into furfural, leveraging a unique pilot-scale setup. Unlike conventional furfural manufacturing processes, which often result in substantial cellulose degradation and environmental concerns associated with sulfuric acid usage, our method utilizes phosphoric acid as a catalyst to achieve high furfural yield while minimizing cellulose destruction. Drawing on our research conducted in a distinctive pilot-scale environment, we successfully developed and implemented a tailored biorefining process for oat husks. Through meticulous experimentation, we attained a remarkable furfural yield of 11.84% from oven-dried mass, accompanied by a 2.64% yield of acetic acid. Importantly, our approach significantly mitigated cellulose degradation, preserving 88.31% of the cellulose content in oat husks. Existing catalytic (H₂SO₄) furfural manufacturing processes often lead to substantial cellulose degradation (40–50%) in lignocellulosic leftover during the pretreatment stage. As a result of the research, it was also possible to reduce the destruction of cellulose in the lignocellulose leftover to 11.69% of the output (initial) cellulose of oat husks. This research underscores the feasibility and sustainability of utilizing oat husks as a valuable feedstock for furfural production, highlighting the potential of phosphoric acid as a catalyst in biorefining processes. By showcasing our unique pilot-scale methodology, this study contributes to advancing the field of environmentally friendly biorefining technologies. Full article

The brewing industry plays a significant role in producing a substantial annual volume of by-products, which contributes to the global accumulation of food waste. The primary by-product generated is brewer’s spent grain (BSG), a lignocellulosic biomass rich in proteins, fiber, and moisture content. Leveraging biorefining and valorization techniques for BSG represents a promising strategy to enhance sustainability, resilience, and circularity within the brewing chain. To date, most studies have focused on extracting proteins from BSG. Yet, it is crucial to note that the fiber part of BSG also holds considerable potential for biorefining processes. This study introduces a novel sequential extraction method designed to integrally recover the major components of BSG. Notably, it introduces a reactive extraction approach that enables the simultaneous extraction and tuneable functionalization of the hemicellulose component. Additionally, the study assesses the utility of the attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy as a user-friendly tool to monitor and evaluate the effectiveness of the fractionation process. This spectroscopic technique can provide valuable insights into the changes and composition of BSG throughout the extraction process. Full article

The use of lignocellulosic biomass as a raw material for the production of lipids has gained increasing attention, especially in recent years when the use of food in the production of biofuels has become a current technology. Thus, the competition for raw materials for both uses has brought the need to create technological alternatives to reduce this competition that could generate a reduction in the volume of food offered and a consequent commercial increase in the value of food. Furthermore, the use of microbial oils has been studied in many industrial branches, from the generation of renewable energy to the obtainment of several value-added products in the pharmaceutical and food industries. Thus, this review provides an overview of the feasibility and challenges observed in the production of microbial lipids through the use of lignocellulosic biomass in a biorefinery. Topics covered include biorefining technology, the microbial oil market, oily microorganisms, mechanisms involved in lipid-producing microbial metabolism, strain development, processes, lignocellulosic lipids, technical drawbacks, and lipid recovery. Full article

The bio-refining process of bamboo is more challenging compared to wood due to its dense and stabilized complex polymer structure, as well as its abundance of degradation-resistant components. Consequently, the bio-refining of bamboo requires more energy and time consumption compared to the bio-refining of wood. In this study, co-cultured microorganisms were utilized for the pretreatment of bamboo to improve pulping performance, reduce consumption, and increase efficiency. These microorganisms were constructed by combining environmental microorganisms found in bamboo pulp with Bacillus sp. that were self-screened. The results of 16S rRNA analysis showed that the genera Proteobacteria, Firmicutes, Bacteroidota, and Actinobacteriota gradually became dominant during the treatment process. Additionally, the PICRUSt results indicated that the co-culture microbial consortium C strategy strengthened key enzyme activities related to the degradation of bamboo lignocelluloses. The microbial consortium pretreatment resulted in removing lignin and hemicellulose at rates of 21.96% and 26.21%, respectively. This process also caused a decrease in the crystalline index, indicating the presence of disordered crystalline regions. This change was beneficial for the subsequent Kraft pulping process. Compared to the conventional bamboo pulp, the yield of pretreated bamboo pulp increased slightly, while the cellulose purity and paper properties were significantly superior. The obtained Kraft pulp, which underwent microbiological pretreatment, met the requirements for superior Kraft pulp products despite a 65 min decrease in cooking time and a 10 °C decline in maximum cooking temperature. This study proves that co-cultured microbial consortium used for pretreating bamboo are beneficial for bamboo Kraft pulping. This approach can be considered environmentally friendly and leads to energy saving and cost reduction in bamboo bio-refining processes. Full article

Utilization of lignin is among the most pressing problems for biorefineries that convert lignocellulosic biomass to fuels and chemicals. Recently “lignin-first” biomass fractionation has received increasing attention. In most biorefining concepts, carbohydrate portions of the biomass are separated, and their monomeric sugar components released, while the relatively chemically stable lignin rich byproduct remains underutilized. Conversely, in lignin-first processes, a one-pot fractionation and depolymerization is performed, leading to an oil rich in phenolic compounds and a cellulosic pulp. Usually, the pulp is considered as a fermentation feedstock to produce ethanol. Herein, the results of a study where various cellulosic pulps are tested for their potential to produce valuable products via pyrolysis processes, assessed via analytical pyrolysis (py-GC), are presented. Samples of herbaceous (switchgrass) and woody biomass (oak) were subjected to both an acid-catalyzed and a supported-metal-catalyzed reductive lignin-first depolymerization, and the pulps were compared. Fast pyrolysis of the pulps produced levoglucosan in yields of up to about 35 wt %. When normalized for the amount of biomass entering the entire process, performing the lignin-first reductive depolymerization resulted in 4.0–4.6 times the yield of levoglucosan than pyrolysis of raw biomass. Pulps derived from switchgrass were better feedstocks for levoglucosan production compared with pulps from oak, and pulps produced from metal-on-carbon catalyzed depolymerization produced more levoglucosan than those from acid-catalyzed depolymerization. Catalytic pyrolysis over HZSM-5 produced aromatic hydrocarbons from the pulps. In this case, the yields were similar from both feedstocks and catalyst types, suggesting that there is no advantage to lignin fractionation prior to zeolite-catalyzed catalytic pyrolysis for hydrocarbons. Full article

This study seeks to improve the effectiveness of the pretreatment stage when direct furfural production is integrated into the concept of a lignocellulosic biomass biorefinery. First of all, the catalytic effects of different phosphorus-containing salts (AlPO₄, Ca₃(PO₄)₂, FePO₄, H₃PO₄, NaH₂PO₄) were analysed in hydrolysis for their ability to convert birch wood C-5 carbohydrates into furfural. The hydrolysis process was performed with three different amounts of catalyst (2, 3 and 4 wt.%) at a constant temperature (175 °C) and treatment time (90 min). It was found that the highest amount of furfural (63–72%, calculated based on the theoretically possible yield (% t.p.y.)) was obtained when H₃PO₄ was used as a catalyst. The best furfural yield among the used phosphorus-containing salts was obtained with NaH₂PO₄: 40 ± 2%. The greatest impact on cellulose degradation during the hydrolysis process was observed using H₃PO₄ at 12–20% of the initial amount, while the lowest degradation was observed using NaH₂PO₄ as a catalyst. The yield of furfural was 60.5–62.7% t.p.y. when H₃PO₄ and NaH₂PO₄ were combined (1:2, 1:1, or 2:1 at a catalyst amount of 3 wt.%); however, the amount of cellulose that was degraded did not exceed 5.2–0.3% of the starting amount. Enzymatic hydrolysis showed that such pretreated biomass could be directly used as a substrate to produce glucose. The highest conversion ratio of cellulose into glucose (83.1%) was obtained at an enzyme load of 1000 and treatment time of 48 h. Full article

Even traditional pretreatments can partially remove or degrade lignin and hemicellulose from lignocellulosic biomass for enhancing its enzymatic digestibility, the remaining lignin in pretreated biomass still restricts its enzymatic hydrolysis by limiting cellulose accessibility and lignin-enzyme nonproductive interaction. Therefore, many pretreatments that can modify lignin structure in a unique way and approaches to block the lignin’s adverse impact have been proposed to directly improve the enzymatic digestibility of pretreated biomass. In this review, recent development in sulfite pretreatment that can transform the native lignin into lignosulfonate and subsequently enhance saccharification of pretreated biomass under certain conditions was summarized. In addition, we also reviewed the approaches of the addition of reactive agents to block the lignin’s reactive sites and limit the cellulase-enzyme adsorption during hydrolysis. It is our hope that this summary can provide a guideline for workers engaged in biorefining for the goal of reaching high enzymatic digestibility of lignocellulose. Full article

Acacia spp. are invasive in Southern Europe, and their high propagation rates produce excessive biomass, exacerbating wildfire risk. However, lignocellulosic biomass from Acacia spp. may be utilised for diverse biorefinery applications. In this study, attenuated total reflectance Fourier transform infrared spectroscopy (FTIR-ATR), high-performance anion-exchange chromatography pulsed amperometric detection (HPAEC-PAD) and lignin content determinations were used for a comparative compositional characterisation of A. dealbata, A. longifolia and A. melanoxylon. Additionally, biomass was treated with three white-rot fungi species (Ganoderma lucidum, Pleurotus ostreatus and Trametes versicolor), which preferentially degrade lignin. Our results showed that the pre-treatments do not significantly alter neutral sugar composition while reducing lignin content. Sugar release from enzymatic saccharification was enhanced, in some cases possibly due to a synergy between white-rot fungi and mild alkali pretreatments. For example, in A. dealbata stems treated with alkali and P. ostreatus, saccharification yield was 702.3 nmol mg⁻¹, which is higher than the samples treated only with alkali (608.1 nmol mg⁻¹), and 2.9-fold higher than the non-pretreated controls (243.9 nmol mg⁻¹). By characterising biomass and pretreatments, generated data creates value for unused biomass resources, contributing to the implementation of sustainable biorefining systems. In due course, the generated value will lead to economic incentives for landowners to cut back invasive Acacia spp. more frequently, thus reducing excess biomass, which exacerbates wildfire risk. Full article

Green biorefining uses fresh lignocellulosic biomass to produce green juice and pressed fibre fractions by wet fractionation. The latter is a byproduct, accounting for 25–32% of the starting material. In this study, the composition (glucan, xylan, arabinan, lignin, total phenol, flavonoid and protein) of pressed fibres obtained from four alfalfa, four soy and one broccoli varieties were determined at different harvest times. Statistical analyses were performed to determine the effects of harvest time and variety on the measured parameters. In most of the cases, there were interactions between the effects of harvest time and variety. Among alfalfa varieties, OLI1 had the highest carbohydrate (52.09 w/w%) and DIM3 had the lowest lignin (13.02 w/w%) content. In the case of soy, the ADV2 variety had the highest carbohydrate (53.47 w/w%) and PK1 had the lowest lignin (11.14 w/w%) content. Broccoli contained low amounts of carbohydrates (44.94 w/w%) and lignin (10.16 w/w%). The phenolic and flavonoid contents were similar for each species, but the protein content was the highest in alfalfa fibre. Based on these data, the most promising species, varieties and harvesting time can be selected in terms of a certain component that could be essential to produce functional foods with enhanced nutritional value. Full article