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Search Results (2,054)

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Keywords = biomass conversion

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14 pages, 1006 KiB  
Article
Oil and Biodiesel Production from Mortierella isabellina Biomass by a Direct Near-Critical Fluid Extraction and Transesterification Method
by Daniela Sallet, Gustavo Andrade Ugalde, Marcus Vinícius Tres, Marcio Antonio Mazutti, Giovani Leone Zabot and Raquel Cristine Kuhn
Biomass 2025, 5(1), 6; https://doi.org/10.3390/biomass5010006 (registering DOI) - 19 Jan 2025
Abstract
Oil and biodiesel produced from lipidic microorganisms are gaining attention in the scientific area. However, intracellular oil needs additional steps for its recovery for transesterification, which generally uses catalysts. In this context, thermal processes that do not use catalysts demand to be investigated. [...] Read more.
Oil and biodiesel produced from lipidic microorganisms are gaining attention in the scientific area. However, intracellular oil needs additional steps for its recovery for transesterification, which generally uses catalysts. In this context, thermal processes that do not use catalysts demand to be investigated. Therefore, the objective was to produce oil and biodiesel from Mortierella isabellina biomass by direct transformation of dry microbial biomass without using a catalyst. Near-critical fluid extraction (nCFE) of lipids followed by direct transesterification was carried out with the same equipment, as an intensification process. A central composite design was used to evaluate the influence of temperature, pressure, and solvent mass-to-feed mass ratio on the extraction yield. Microbial lipids produced by submerged fermentation and extracted by nCFE with ethanol were used for biodiesel production. The highest total extraction yield (55.4 wt%) and biodiesel conversion (22.2%) were obtained at 300 °C and 20 MPa with 30 g of ethanol/g of fungal biomass. The other conditions yielded extraction yields and biodiesel conversions ranging from 9.7 to 46.0% and from 1.5 to 22.0%, respectively. The interaction between temperature and pressure was significant (p < 0.05), with a positive correlation, indicating that higher temperatures and pressures yielded higher biodiesel conversion rates. The process intensification is advantageous because it is developed sequentially in one step and uses only ethanol as a solvent/reagent, without catalysts. Therefore, the direct extraction and transesterification of Mortierella isabellina lipids demonstrated to be technically feasible and an environmentally friendly technology for the production of fungal oil and biodiesel. The oil can be used in the food and cosmetic industries because it has nutrients that regulate physiological mechanisms promoting human health, while biodiesel can be used in the transport sector and in stationary engines. Full article
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Figure 1
<p>Schematic illustration of the homemade equipment: 1—pump for the liquid; 2—pre-heating bath; 3—reactor A; 4—reactor B; 5—temperature control system; 6—cooling bath; 7—micrometering valve; 8—sample flask.</p>
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<p>Kinetic yields of extracted compounds obtained from <span class="html-italic">Mortierella isabellina</span>; top graphic: assays 1—4; middle graphic: assays 5—8; bottom graphic: assays 9—11.</p>
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<p>Standardized Pareto chart for effect estimate of process variables on total extraction yields and biodiesel conversion.</p>
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<p>Example of mass balance for oil plus biodiesel production from <span class="html-italic">Mortierella isabellina</span> biomass by a direct extraction and transesterification method with the process conditions defined in Assay 1.</p>
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27 pages, 1692 KiB  
Article
Optimizing Hydrogen Production in the Co-Gasification Process: Comparison of Explainable Regression Models Using Shapley Additive Explanations
by Thavavel Vaiyapuri
Entropy 2025, 27(1), 83; https://doi.org/10.3390/e27010083 (registering DOI) - 17 Jan 2025
Viewed by 289
Abstract
The co-gasification of biomass and plastic waste offers a promising solution for producing hydrogen-rich syngas, addressing the rising demand for cleaner energy. However, optimizing this complex process to maximize hydrogen yield remains challenging, particularly when balancing diverse feedstocks and improving process efficiency. While [...] Read more.
The co-gasification of biomass and plastic waste offers a promising solution for producing hydrogen-rich syngas, addressing the rising demand for cleaner energy. However, optimizing this complex process to maximize hydrogen yield remains challenging, particularly when balancing diverse feedstocks and improving process efficiency. While machine learning (ML) has shown significant potential in simulating and optimizing such processes, there is no clear consensus on the most effective regression models for co-gasification, especially with limited experimental data. Additionally, the interpretability of these models is a key concern. This study aims to bridge these gaps through two primary objectives: (1) modeling the co-gasification process using seven different ML algorithms, and (2) developing a framework for evaluating model interpretability, ultimately identifying the most suitable model for process optimization. A comprehensive set of experiments was conducted across three key dimensions, generalization ability, predictive accuracy, and interpretability, to thoroughly assess the models. Support Vector Regression (SVR) exhibited superior performance, achieving the highest coefficient of determination (R2) of 0.86. SVR outperformed other models in capturing non-linear dependencies and demonstrated effective overfitting mitigation. This study further highlights the limitations of other ML models, emphasizing the importance of regularization and hyperparameter tuning in improving model stability. By integrating Shapley Additive Explanations (SHAP) into model evaluation, this work is the first to provide detailed insights into feature importance and demonstrate the operational feasibility of ML models for industrial-scale hydrogen production in the co-gasification process. The findings contribute to the development of a robust framework for optimizing co-gasification, supporting the advancement of sustainable energy technologies and the reduction of greenhouse gas (GHG) emissions. Full article
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<p>Evaluation framework for explainable ML models in hydrogen yield prediction.</p>
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<p>Box plot for outlier analysis.</p>
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<p>Heat map for correlation analysis.</p>
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<p>Learning curve analysis of all explainable ML models with optimized hyperparameters. (<b>a</b>) LR, (<b>b</b>) KNN, (<b>c</b>) DTR, (<b>d</b>) SVR, (<b>e</b>) GBR, (<b>f</b>) RFR, (<b>g</b>) MLP.</p>
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<p>Learning curve analysis of all explainable ML models with default hyperparameters. (<b>a</b>) LR, (<b>b</b>) KNN, (<b>c</b>) DTR, (<b>d</b>) SVR, (<b>e</b>) GBR, (<b>f</b>) RFR, (<b>g</b>) MLP.</p>
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<p>Box Plot of 5-CV results for all explainable ML models in hydrogen yield prediction. (<b>a</b>) Default hyperparameters, (<b>b</b>) Optimized hyperparameters.</p>
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<p>Line graph illustrating the statistical performance metrics for all explainable ML models. (<b>a</b>) Default hyperparameters, (<b>b</b>) Optimized hyperparameters.</p>
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<p>Scatter plots of all explainable ML models with default hyperparameters for hydrogen yield prediction analysis. (<b>a</b>) LR, (<b>b</b>) KNN, (<b>c</b>) DTR, (<b>d</b>) SVR, (<b>e</b>) GBR, (<b>f</b>) RFR, (<b>g</b>) MLP.</p>
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<p>Scatter plots of all explainable ML models with optimized hyperparameters for hydrogen yield prediction analysis. (<b>a</b>) LR, (<b>b</b>) KNN, (<b>c</b>) DTR, (<b>d</b>) SVR, (<b>e</b>) GBR, (<b>f</b>) RFR, (<b>g</b>) MLP.</p>
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<p>SHAP summary plots of all explainable ML models in hydrogen yield prediction. (<b>a</b>) LR, (<b>b</b>) KNN, (<b>c</b>) DTR, (<b>d</b>) SVR, (<b>e</b>) GBR, (<b>f</b>) RFR, (<b>g</b>) MLP.</p>
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<p>SHAP force plots of all explainable ML models for an instance yielding low hydrogen.</p>
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<p>SHAP force plots of all explainable ML models for an instance yielding high hydrogen.</p>
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16 pages, 3317 KiB  
Article
Neural Network for AI-Driven Prediction of Larval Protein Yield: Establishing the Protein Conversion Index (PCI) for Sustainable Insect Farming
by Claudia L. Vargas-Serna, Angie N. Pineda-Osorio, Carlos A. Gomez-Velasco, Jose Luis Plaza-Dorado and Claudia I. Ochoa-Martinez
Sustainability 2025, 17(2), 652; https://doi.org/10.3390/su17020652 - 16 Jan 2025
Viewed by 369
Abstract
The predictive capabilities of artificial intelligence for predicting protein yield from larval biomass present valuable advancements for sustainable insect farming, an increasingly relevant alternative protein source. This study develops a neural network model to predict protein conversion efficiency based on the nutritional composition [...] Read more.
The predictive capabilities of artificial intelligence for predicting protein yield from larval biomass present valuable advancements for sustainable insect farming, an increasingly relevant alternative protein source. This study develops a neural network model to predict protein conversion efficiency based on the nutritional composition of larval feed. The model utilizes a structured two-layer neural network with four neurons in each hidden layer and one output neuron, employing logistic sigmoid functions in the hidden layers and a linear function in the output layer. Training is performed via Bayesian regularization backpropagation to minimize mean squared error, resulting in a high regression coefficient (R = 0.9973) and a low mean-squared error (MSE = 0.0072401), confirming the precision of the model in estimating protein yields. This AI-driven approach serves as a robust tool for predicting larval protein yields, enhancing resource efficiency and promoting sustainability in insect-based protein production. Full article
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<p>General structure of the neural network construction (research workflow).</p>
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<p>Regression plot of the initial network predictions against the target values.</p>
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<p>Predicted versus observed values in the initial network for (<b>A</b>) training, (<b>B</b>) validation, and (<b>C</b>) test sets.</p>
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<p>Network configuration.</p>
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<p>Interface of the Neural Network Prediction Tool for the real-time prediction of protein conversion efficiency.</p>
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<p>Sensitivity of the network output to each input feature (gradient method).</p>
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<p>Permutation sensitivity analysis for each input feature.</p>
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14 pages, 3491 KiB  
Article
Selective Synthesis of Isoquinoline-1-Carboxamides via Palladium-Catalyzed Aminocarbonylation in DMF and Biomass-Derived Solvents
by László Kollár, Nuray Uzunlu Ince, Alexandra Zugó, Ágnes Dörnyei and Attila Takács
Catalysts 2025, 15(1), 78; https://doi.org/10.3390/catal15010078 - 15 Jan 2025
Viewed by 349
Abstract
In this study, the palladium-catalyzed aminocarbonylation of 1-iodoisoquinoline was accomplished in the presence of various amines. While the reactions with simple primary and secondary amines were carried out by using the well-known Pd(OAc)2/PPh3 catalyst, the application of amines with lower [...] Read more.
In this study, the palladium-catalyzed aminocarbonylation of 1-iodoisoquinoline was accomplished in the presence of various amines. While the reactions with simple primary and secondary amines were carried out by using the well-known Pd(OAc)2/PPh3 catalyst, the application of amines with lower basicity (e.g., aromatic amines) or more difficult structures (e.g., amino acid methyl esters, nortropine, diethyl (α-aminobenzyl)phosphonate) required the use of bidentate XantPhos ligand to achieve complete conversion in short reaction time (2–8 h). In this way, several valuable isoquinoline-1-carboxamides were synthesized in chemoselective carbonylation and isolated in good to high yields (55–89%). Furthermore, the aminocarbonylation of the model compound in the presence of several amines was also investigated in three biomass-derived solvents (GVL, ethyl levulinate, and 2-MeTHF). After comparing the outcome of the reactions in DMF and the above green solvents, similar reactivity was observed, justifying that they could be considered a feasible alternative reaction medium. Full article
(This article belongs to the Special Issue Catalysis in Heterocyclic and Organometallic Synthesis, 3rd Edition)
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Graphical abstract

Graphical abstract
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<p>Biologically or pharmaceutically active isoquinolines containing the amide structural motif.</p>
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<p>Isoquinoline-1-carboxamides (<b>1a</b>–<b>1z</b>) synthesized in the Pd-catalyzed aminocarbonylation of 1-iodoisoquinoline (<b>1</b>). The asymmetric carbon atom is indicated by asterisk symbol.</p>
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<p>Palladium-catalyzed aminocarbonylation of 1-iodoisoquinoline (<b>1</b>) in DMF and different green solvents (GVL, EtLev, 2-MeTHF) in the presence of amines <b>a</b>, <b>b</b>, <b>c</b>, <b>e</b>, <b>f</b>, <b>r</b>, <b>t</b>, and <b>w</b> in the presence of Pd(OA)<sub>2</sub>/PPh<sub>3</sub> or Pd(OA)<sub>2</sub>/XantPhos under the same conditions as in the case of DMF. The conversions were detected by GC-MS after 8 h of reaction time.</p>
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<p>Comparison of isolated yields of isoquinoline1-carboxamides (<b>1f</b>, <b>1p</b>, and <b>1t</b>) in DMF, GVL, and EtLev.</p>
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<p>Possible synthetic routes for producing isoquinoline-1-carboxamides.</p>
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<p>Palladium-catalyzed aminocarbonylation of 1-iodoisoquinoline (<b>1</b>) in green solvents.</p>
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22 pages, 6292 KiB  
Review
Review of Bioinspired Composites for Thermal Energy Storage: Preparation, Microstructures and Properties
by Min Yu, Mengyuan Wang, Changhao Xu, Wei Zhong, Haoqi Wu, Peng Lei, Zeya Huang, Renli Fu, Francesco Gucci and Dou Zhang
J. Compos. Sci. 2025, 9(1), 41; https://doi.org/10.3390/jcs9010041 - 15 Jan 2025
Viewed by 388
Abstract
Bioinspired composites for thermal energy storage have gained much attention all over the world. Bioinspired structures have several advantages as the skeleton for preparing thermal energy storage materials, including preventing leakage and improving thermal conductivity. Phase change materials (PCMs) play an important role [...] Read more.
Bioinspired composites for thermal energy storage have gained much attention all over the world. Bioinspired structures have several advantages as the skeleton for preparing thermal energy storage materials, including preventing leakage and improving thermal conductivity. Phase change materials (PCMs) play an important role in the development of energy storage materials because of their stable chemical/thermal properties and high latent heat storage capacity. However, their applications have been compromised, owing to low thermal conductivity and leakage. The plant-derived scaffolds (i.e., wood-derived SiC/Carbon) in the composites can not only provide higher thermal conductivity but also prevent leakage. In this paper, we review recent progress in the preparation, microstructures, properties and applications of bioinspired composites for thermal energy storage. Two methods are generally used for producing bioinspired composites, including the direct introduction of biomass-derived templates and the imitation of biological structures templates. Some of the key technologies for introducing PCMs into templates involves melting, vacuum impregnation, physical mixing, etc. Continuous and orderly channels inside the skeleton can improve the overall thermal conductivity, and the thermal conductivity of composites with biomass-derived, porous, silicon carbide skeleton can reach as high as 116 W/m*K. In addition, the tightly aligned microporous structure can cover the PCM well, resulting in good leakage resistance after up to 2500 hot and cold cycles. Currently, bioinspired composites for thermal energy storage hold the greatest promise for large-scale applications in the fields of building energy conservation and solar energy conversion/storage. This review provides guidance on the preparation methods, performance improvements and applications for the future research strategies of bioinspired composites for thermal energy storage. Full article
(This article belongs to the Section Composites Manufacturing and Processing)
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<p>Summary of wood-derived carbides (<b>a</b>) and SEM images of microstructure of natural materials: (<b>b</b>) quercus laevis, (<b>c</b>) sugarcane, (<b>d</b>) sycamore fruit fiber and (<b>e</b>) grapefruit peel (adapted from Refs. [<a href="#B37-jcs-09-00041" class="html-bibr">37</a>,<a href="#B44-jcs-09-00041" class="html-bibr">44</a>]).</p>
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<p>Bioinspired templates and microstructures for thermal energy storage composites.</p>
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<p>Simplified flow chart of processing bioinspired composites for thermal energy storage.</p>
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<p>Summary of the impregnation methods for preparing bioinsipired ceramics/ceramic matrix composites in our research group: (<b>a</b>) polymer precursor impregnation, (<b>b</b>) sol-gel impregnation method, (<b>c</b>) slurry impregnation method, (<b>d</b>) physical vapor phase impregnation method (flowchart of material preparation inserted in <a href="#jcs-09-00041-f004" class="html-fig">Figure 4</a> adapted from references [<a href="#B41-jcs-09-00041" class="html-bibr">41</a>,<a href="#B44-jcs-09-00041" class="html-bibr">44</a>,<a href="#B45-jcs-09-00041" class="html-bibr">45</a>]).</p>
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<p>Processing of skeleton materials for bioinspired thermal energy storage composites.</p>
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<p>Processing of bioinspired composites for thermal energy storage.</p>
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<p>Working temperature diagram of bioinspired composites for thermal energy storage. (Inserted SEM images in <a href="#jcs-09-00041-f007" class="html-fig">Figure 7</a> are adapted from [<a href="#B33-jcs-09-00041" class="html-bibr">33</a>,<a href="#B57-jcs-09-00041" class="html-bibr">57</a>,<a href="#B59-jcs-09-00041" class="html-bibr">59</a>,<a href="#B62-jcs-09-00041" class="html-bibr">62</a>,<a href="#B63-jcs-09-00041" class="html-bibr">63</a>,<a href="#B69-jcs-09-00041" class="html-bibr">69</a>,<a href="#B70-jcs-09-00041" class="html-bibr">70</a>,<a href="#B74-jcs-09-00041" class="html-bibr">74</a>,<a href="#B77-jcs-09-00041" class="html-bibr">77</a>]).</p>
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<p>Heat transfer mechanism of bioinspired composites.</p>
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<p>Heat storage performance diagram of bioinspired composites for thermal energy storage: (<b>a</b>) Summary of heat storage properties of (bioinspired inorganic skeleton-inorganic PCMs) [<a href="#B55-jcs-09-00041" class="html-bibr">55</a>,<a href="#B56-jcs-09-00041" class="html-bibr">56</a>,<a href="#B57-jcs-09-00041" class="html-bibr">57</a>,<a href="#B67-jcs-09-00041" class="html-bibr">67</a>]. (<b>b</b>) Summary of heat storage properties of (bioinspired inorganic skeleton-organic PCMs) [<a href="#B29-jcs-09-00041" class="html-bibr">29</a>,<a href="#B32-jcs-09-00041" class="html-bibr">32</a>,<a href="#B33-jcs-09-00041" class="html-bibr">33</a>,<a href="#B34-jcs-09-00041" class="html-bibr">34</a>,<a href="#B60-jcs-09-00041" class="html-bibr">60</a>,<a href="#B61-jcs-09-00041" class="html-bibr">61</a>,<a href="#B63-jcs-09-00041" class="html-bibr">63</a>,<a href="#B70-jcs-09-00041" class="html-bibr">70</a>,<a href="#B72-jcs-09-00041" class="html-bibr">72</a>,<a href="#B73-jcs-09-00041" class="html-bibr">73</a>,<a href="#B76-jcs-09-00041" class="html-bibr">76</a>,<a href="#B77-jcs-09-00041" class="html-bibr">77</a>].</p>
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<p>Bioinspired composites for thermal energy storage application system diagram.</p>
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20 pages, 3067 KiB  
Article
High-Yield Production of Polyhydroxybutyrate and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from Crude Glycerol by a Newly Isolated Burkholderia Species Oh_219
by Suk-Jin Oh, Gaeun Lim, Yebin Han, Wooseong Kim, Hwang-Soo Joo, Yun-Gon Kim, Jae-Seok Kim, Shashi Kant Bhatia and Yung-Hun Yang
Polymers 2025, 17(2), 197; https://doi.org/10.3390/polym17020197 - 14 Jan 2025
Viewed by 308
Abstract
Crude glycerol (CG), a major biodiesel production by-product, is the focus of ongoing research to convert it into polyhydroxyalkanoate (PHA). However, few bacterial strains are capable of efficiently achieving this conversion. Here, 10 PHA-producing strains were isolated from various media. Among them, Burkholderia [...] Read more.
Crude glycerol (CG), a major biodiesel production by-product, is the focus of ongoing research to convert it into polyhydroxyalkanoate (PHA). However, few bacterial strains are capable of efficiently achieving this conversion. Here, 10 PHA-producing strains were isolated from various media. Among them, Burkholderia sp. Oh_219 exhibited the highest polyhydroxybutyrate (PHB) production from glycerol and was therefore characterized further. Burkholderia sp. Oh_219 demonstrated significant tolerance to major growth inhibitors in CG and metabolized the fatty acids present as impurities in CG. Furthermore, the Oh_219 strain was genetically engineered using phaCBP-M-CPF4 and phaJPa to enable the fatty acid-based production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a component of CG. The resulting strain produced PHBHHx containing 1.0–1.3 mol% of 3HHx from CG. Further supplementation with capric and lauric acids increased the 3HHx molar fraction to 9.7% and 18%, respectively. In a 5 L fermenter, the Oh_219 strain produced 15.3 g/L PHB from 29.6 g/L biomass using a two-stage fermentation system. This is the highest yield reported for PHA production from glycerol by Burkholderia spp. Additionally, PHB produced from CG had a lower melting point than that from pure glycerol and fructose. Taken together, Burkholderia sp. Oh_219 is a promising new candidate strain for producing PHA from CG. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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<p>Confirmation of PHB production capacity from glycerol in 10 PHB-producing strains (<b>a</b>). Phylogenetic analysis of the 12 PHB-producing strains (<b>b</b>). PHB, polyhydroxybutyrate; DCW, dry cell weight.</p>
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<p>Optimization of glycerol concentration (<b>a</b>) and nitrogen source (<b>b</b>) to enhance PHB production in <span class="html-italic">Burkholderia</span> sp. Oh_219. Tolerance tests for methanol (<b>c</b>) and NaCl (<b>d</b>) in Oh_219 strain. PHB, polyhydroxybutyrate; DCW, dry cell weight.</p>
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<p>Evaluation of fatty acid metabolism in <span class="html-italic">Burkholderia</span> sp. Oh_219. Growth of Oh_219 with single fatty acids as the sole carbon source (<b>a</b>). PHB production by Oh_219 when single fatty acids are supplemented alongside glycerol (<b>b</b>). Assessment of P(3HB-<span class="html-italic">co</span>-3HHx) production in Oh_219 harboring <span class="html-italic">phaC</span><sub>BP-M-CPF4</sub> and <span class="html-italic">phaJ<sub>Pa</sub></span>. P(3HB-<span class="html-italic">co</span>-3HHx) production by Oh_219 at various concentrations of capric (<b>c</b>) and lauric (<b>d</b>) acids added to crude glycerol. PHB, polyhydroxybutyrate; DCW, dry cell weight; C-source, carbon source; 3HB, 3-hydroxybutyrate; 3HHx, 3-hydroxyhexanoate; CG, crude glycerol.</p>
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<p>Time-dependent comparison of cell growth and PHB production by Oh_219 using pure glycerol (<b>a</b>) versus crude glycerol (<b>b</b>). PHB, polyhydroxybutyrate; DCW, dry cell weight.</p>
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<p>Two fermentation strategies for large-scale PHB production from glycerol. The first strategy enabled continuous cell growth and PHB accumulation by supplying glycerol and a small amount of urea (<b>a</b>,<b>b</b>). The second strategy involved a two-stage fermentation process, where glycerol and urea were fed at the same concentration to boost cell mass, followed by PHB accumulation with reduced urea supply (<b>c</b>,<b>d</b>). Gly, glycerol; PHB, polyhydroxybutyrate; DCW, dry cell weight.</p>
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<p>Two fermentation strategies for large-scale PHB production from glycerol. The first strategy enabled continuous cell growth and PHB accumulation by supplying glycerol and a small amount of urea (<b>a</b>,<b>b</b>). The second strategy involved a two-stage fermentation process, where glycerol and urea were fed at the same concentration to boost cell mass, followed by PHB accumulation with reduced urea supply (<b>c</b>,<b>d</b>). Gly, glycerol; PHB, polyhydroxybutyrate; DCW, dry cell weight.</p>
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<p>Contact angles of PHB films produced from fructose (<b>a</b>), pure glycerol (<b>b</b>), or crude glycerol (<b>c</b>) by <span class="html-italic">Burkholderia</span> sp. Oh_219. The blue lines represent the baseline, while the red lines indicate the tangents to the droplet’s profile.</p>
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19 pages, 3014 KiB  
Article
Impact of Enzymatic Degradation Treatment on Physicochemical Properties, Antioxidant Capacity, and Prebiotic Activity of Lilium Polysaccharides
by Kaitao Peng, Yujie Zhang, Qi Zhang, Yunpu Wang, Yuhuan Liu and Xian Cui
Foods 2025, 14(2), 246; https://doi.org/10.3390/foods14020246 - 14 Jan 2025
Viewed by 391
Abstract
In order to overcome the bioavailability limitation of Lilium polysaccharide (LPS) caused by its high molecular weight and complex structure, two low-molecular-weight degraded polysaccharides, namely G-LPS(8) and G-LPS(16), were prepared through enzymatic degradation. The molecular weight of LPS was significantly reduced by enzymolysis, [...] Read more.
In order to overcome the bioavailability limitation of Lilium polysaccharide (LPS) caused by its high molecular weight and complex structure, two low-molecular-weight degraded polysaccharides, namely G-LPS(8) and G-LPS(16), were prepared through enzymatic degradation. The molecular weight of LPS was significantly reduced by enzymolysis, leading to increased exposure of internal functional groups and altering the molar ratio of its constituent monosaccharides. The results of antioxidant experiments showed that enzymatic hydrolysis had the potential to enhance the antioxidant performance of LPS. In vitro fermentation experiments revealed that LPS and its derivatives exerted different prebiotic effects on intestinal microbial communities. Specifically, LPS mainly inhibited the growth of harmful bacteria such as Fusobacterium, while G-LPS(8) and G-LPS(16) tended to promote the growth of beneficial bacteria like Megamonas, Bacteroides, and Parabacteroides. Metabolomic analysis revealed that LPSs with varying molecular weights exerted comparable promoting effects on multiple amino acid and carbohydrate metabolic pathways. Importantly, with the reduction in molecular weight, G-LPS(16) also particularly stimulated sphingolipid metabolism, nucleotide metabolism, as well as ascorbic acid and uronic acid metabolism, leading to the significant increase in specific metabolites such as sphingosine. Therefore, this study suggests that properly degraded LPS components have greater potential as a prebiotic for improving gut health. Full article
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Figure 1
<p>FT-IR spectra of LPS, G-LPS(8), and G-LPS(16) in the range of 4000–400 cm<sup>−1</sup>. LPS represents the original <span class="html-italic">Lilium</span> polysaccharide, and G-LPS(8) and G-LPS(16) are degradation products of LPS treated with 0.8 × 10<sup>3</sup> U/g and 1.6 × 10<sup>3</sup> U/g β-glucanase, respectively.</p>
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<p>Changes in antioxidant capacity. Including the scavenging activities of LPS, G-LPS(8), G-LPS(16), and V<sub>C</sub> on (<b>A</b>) DPPH (<b>B</b>) and ABTS free radicals at different concentrations. LPS represents the original <span class="html-italic">Lilium</span> polysaccharide, and G-LPS(8) and G-LPS(16) are degradation products of LPS treated with 0.8 × 10<sup>3</sup> U/g and 1.6 × 10<sup>3</sup> U/g β-glucanase, respectively. In the same column, distinct lowercase letters represent statistically significant differences between treatments (<span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Changes in pH value during fermentation. In the same column, distinct lowercase letters represent statistically significant differences between treatments (<span class="html-italic">p</span> &lt; 0.05). LPS represents the original <span class="html-italic">Lilium</span> polysaccharide, and G-LPS(8) and G-LPS(16) are degradation products of LPS treated with 0.8 × 10<sup>3</sup> U/g and 1.6 × 10<sup>3</sup> U/g β-glucanase, respectively.</p>
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<p>Structure of gut microbial community after 48 h <span class="html-italic">in vitro</span> fermentation. (<b>A</b>) Histograms of relative species abundance at the phylum level, (<b>B</b>) histograms of relative species abundance at the genus level, (<b>C</b>) Venn plots of gut microbiota, and (<b>D</b>) heatmap analysis of gut microbial community structure at the genus level for different samples. CO was fermented in blank control medium for 48 h; LPS, G_LPS8, and G_LPS16 were fermented in medium supplemented with LPS, G-LPS(8), and G-LPS(16) for 48 h, respectively.</p>
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<p>Metabolite changes induced by LPS, G-LPS(8), and G-LPS(16) after 48 h <span class="html-italic">in vitro</span> fermentation. (<b>A</b>) PCA analysis of metabolomics data. Different groups are represented by different colors. (<b>B</b>) PLS-DA replacement test. Q2 value &lt; 0.05 indicates that the model is robust and reliable without overfitting. (<b>C</b>) Venn diagram of differentiated metabolites between groups. OPLS-DA scores of (<b>D</b>) LPS, (<b>E</b>) G-LPS(8), (<b>F</b>) G-LPS(16), and CO groups. CO was fermented in blank control medium for 48 h; LPS, G_LPS8, and G_LPS16 were fermented in medium supplemented with LPS, G-LPS(8), and G-LPS(16) for 48 h, respectively.</p>
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<p>Volcanic maps of metabolite differences between (<b>A</b>) G-LPS(8), (<b>B</b>) G-LPS(16), and LPS groups after 48 h <span class="html-italic">in vitro</span> fermentation. (<b>C</b>) Heatmap of differential metabolites (VIP ≥ 2, <span class="html-italic">p</span> &lt; 0.05, with FC ≥ 1). On the right, a bar chart displays the VIP values of metabolites, where the length of each bar reflects the metabolite’s contribution to the observed differences between the two groups, with a minimum value of 1. Larger values correspond to greater differences. The color of each bar represents the significance of the metabolite differences, with darker colors indicating smaller <span class="html-italic">p</span>-values and, consequently, more significant differences. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.001. CO was fermented in blank control medium for 48 h; LPS, G_LPS8, and G_LPS16 were fermented in medium supplemented with LPS, G-LPS(8), and G-LPS(16) for 48 h, respectively.</p>
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<p>Remarkably changed KEGG pathways among CO, LPS, G-LPS(8), and G-LPS(16) groups after 48 h <span class="html-italic">in vitro</span> fermentation. CO was fermented in blank control medium for 48 h; LPS, G_LPS8, and G_LPS16 were fermented in medium supplemented with LPS, G-LPS(8), and G-LPS(16) for 48 h, respectively.</p>
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16 pages, 3993 KiB  
Article
Transformation of NO in Combustion Gases by DC Corona
by Oleksandr Molchanov, Kamil Krpec, Jiří Horák, Lenka Kuboňová, František Hopan, Jiří Ryšavý and Marcelina Bury
Fire 2025, 8(1), 21; https://doi.org/10.3390/fire8010021 - 8 Jan 2025
Viewed by 545
Abstract
This study investigates the performance of DC corona discharge electrostatic precipitators (ESPs) for NO conversion to increase DeNOx technologies’ efficiency for small-scale biomass combustion systems. Experiments were conducted using a 5 kW automatic wood pellet domestic heat source with combustion gas treated [...] Read more.
This study investigates the performance of DC corona discharge electrostatic precipitators (ESPs) for NO conversion to increase DeNOx technologies’ efficiency for small-scale biomass combustion systems. Experiments were conducted using a 5 kW automatic wood pellet domestic heat source with combustion gas treated in a specially designed ESP operated in both positive and negative corona modes, resulting in a reduction in NO concentrations from 130 mg/m3 to 27/29 mg/m3 for positive/negative polarities (at 0 °C and 101.3 kPa). NO conversion efficiency was evaluated across a range of specific input energies (SIEs) from 0 to 50 J/L. The results demonstrate that DC corona ESPs can achieve up to 78% NO reduction, with positive corona demonstrating a greater energy efficiency, requiring a lower SIE (35 J/L) compared to the negative corona mode (48 J/L). A detailed analysis of reaction pathways revealed distinct conversion mechanisms between the two modes. In positive corona, dispersed active species distribution led to more uniform NO conversion, while negative corona exhibited concentrated reaction zones with about 20% higher ozone production. The reactions involving O and OH radicals were more important in positive corona, whereas ozone-mediated oxidation dominated in negative corona. The research results demonstrate that ESP technology with DC corona offers a promising, energy-efficient solution for NOx control in small-scale combustion systems. Full article
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<p>Experimental setup.</p>
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<p>The corona current and SIE with the applied voltage.</p>
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<p>Electron and active species density distributions for negative (<b>A</b>) and positive (<b>B</b>) corona.</p>
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<p>Ozone concentrations with SIE.</p>
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<p>The efficiency of NO oxidation and reduction in negative (<b>A</b>) and positive (<b>B</b>) DC corona.</p>
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<p>The efficiency of NO conversion with ESP energization.</p>
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16 pages, 2963 KiB  
Article
Competitive Adsorption of Pb2+ from Aqueous Solutions by Multi-Source Lignocellulose-Derived Hydrothermal Humic Acid
by Changzhi Song, Junhao Liu, Libo Zhang, Jianing Wang and Xinqian Shu
Processes 2025, 13(1), 155; https://doi.org/10.3390/pr13010155 - 8 Jan 2025
Viewed by 331
Abstract
This study explores the conversion of lignocellulosic biomass from softwood, hardwood, and grasses into humic acid via a mild hydrothermal process and its application in Pb2+ adsorption. The investigation focused on adsorption isotherms, kinetics, thermodynamics, and the intraparticle diffusion model to evaluate [...] Read more.
This study explores the conversion of lignocellulosic biomass from softwood, hardwood, and grasses into humic acid via a mild hydrothermal process and its application in Pb2+ adsorption. The investigation focused on adsorption isotherms, kinetics, thermodynamics, and the intraparticle diffusion model to evaluate the adsorption performance of humic acids from different sources. The results indicate that the humic acid of broad-leaved wood (Eucalyptus-HA) possesses the optimal adsorption capacity and removal efficiency of Pb2+. When the initial concentration of Pb2+ is 100 mg/L, the adsorption capacity and removal efficiency of Eucalyptus-HA reach 49.75 mg/g and 25.57%, respectively, which are far higher than the adsorption capacity (26.82 mg/g) and removal efficiency (13.71%) of commercial humic acid (Commercial-HA). The pore structure of humic acid plays a critical role in its Pb2+ adsorption capacity. High Pb2+ concentrations and a low pH negatively impact adsorption efficiency, and instability in the humic acid pore structure affects reproducibility. Adsorption isotherm fitting showed that Pb2+ adsorption conforms most closely to the Langmuir model. While commercial humic acid exhibited faster adsorption rates, its capacity was constrained by thermodynamic limitations and lower specific surface areas. The intraparticle diffusion model revealed that Pb2+ diffusion proceeded more efficiently in hydrothermal humic acids than in commercial ones due to lower diffusion resistance. This study highlights the potential of feedstock source regulation to enhance humic acid’s heavy metal adsorption capabilities, expanding its application across various fields. Full article
(This article belongs to the Special Issue Platform Chemicals and Novel Materials from Biomass)
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<p>Humic acid molecular structure diagram.</p>
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<p>Comparison of Pb<sup>2+</sup> adsorption capacities of humic acids from different sources: adsorption amount (<b>a</b>) and removal efficiency (<b>b</b>). The initial concentration of Pb<sup>2+</sup> is 100 mg/L, with an initial solution pH of 5.0, a humic acid adsorbent mass of 0.1 g, and an adsorption temperature of 25 °C.</p>
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<p>Effect of initial concentration (<b>a</b>) and pH (<b>b</b>) on equilibrium adsorption capacity of Pb<sup>2+</sup> by Eucalyptus-HA and Commercial-HA. (<b>a</b>) The initial concentrations of Pb<sup>2+</sup> were 10, 20, 50, 100, and 200 mg/L, the initial pH of the adsorbent was 5.0, the mass of the adsorbent humic acid was 0.1 g, the adsorption temperature was 25 °C, and the adsorption time was 180 min. (<b>b</b>) The initial concentration of Pb<sup>2+</sup> was 100 mg/L, the mass of the adsorbent humic acid was 0.1 g, the adsorption temperature was 25 °C, and the adsorption time was 180 min.</p>
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<p>Repeated use of Eucalyptus-HA and Commercial-HA for Pb<sup>2+</sup> adsorption: equilibrium adsorption capacity (<b>a</b>) and removal efficiency (<b>b</b>). Initial Pb<sup>2+</sup> concentration was 100 mg/L, with an initial pH of 5.0, an adsorbent mass of 0.1 g, an adsorption temperature of 25 °C, and an adsorption duration of 180 min.</p>
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<p>Adsorption isotherm fitting for Pb<sup>2+</sup> by Eucalyptus-HA and Commercial-HA: (<b>a</b>) Langmuir adsorption model fitting and (<b>b</b>) Freundlich adsorption model fitting. Initial Pb<sup>2+</sup> concentrations were 10, 20, 50, 100, and 200 mg/L, with an initial solution pH of 5.0, a humic acid mass of 0.1 g, and an adsorption duration of 180 min.</p>
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<p>The fitting of quasi-first-order and quasi-second-order kinetic models for Pb<sup>2+</sup> adsorption onto Eucalyptus-HA and Commercial-HA. The initial Pb<sup>2+</sup> concentration was 100 mg/L, with an initial solution pH of 5.0 and 0.1 g of humic acid used as the adsorbent. (<b>a</b>) Fitting of quasi-first-order kinetic model and (<b>b</b>) fitting of quasi-second-order kinetic model.</p>
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<p>Intraparticle diffusion model of Pb<sup>2+</sup> adsorbed onto Commercial-HA and Eucalyptus-HA at different temperatures: (<b>a</b>) 298.15 K, (<b>b</b>) 308.15 K, and (<b>c</b>) 318.15 K.</p>
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6 pages, 355 KiB  
Editorial
Preface: III International Congress: Technology and Innovation in Engineering and Computing
by Luis Olivera-Montenegro
Eng. Proc. 2025, 83(1), 5; https://doi.org/10.3390/engproc2025083005 - 7 Jan 2025
Viewed by 361
Abstract
The III International Congress: Technology and Innovation in Engineering and Computing, organized by Faculty of Engineering, St [...] Full article
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<p>Logo of USIL.</p>
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15 pages, 1812 KiB  
Article
Boosted Bio-Oil Production and Sustainable Energy Resource Recovery Through Optimizing Oxidative Pyrolysis of Banana Waste
by Rohit K. Singh, Bhavin Soni, Urvish Patel, Asim K. Joshi and Sanjay K. S. Patel
Fuels 2025, 6(1), 3; https://doi.org/10.3390/fuels6010003 - 7 Jan 2025
Viewed by 440
Abstract
The increasing need for sustainable waste management and abundant availability of banana tree waste, a byproduct of widespread banana cultivation, have driven interest in biomass conversion through clean fuels. This study investigates the oxidative pyrolysis of banana tree waste to optimize process parameters [...] Read more.
The increasing need for sustainable waste management and abundant availability of banana tree waste, a byproduct of widespread banana cultivation, have driven interest in biomass conversion through clean fuels. This study investigates the oxidative pyrolysis of banana tree waste to optimize process parameters and enhance bio-oil production. Experiments were conducted using a fluidized bed reactor at temperatures ranging from 450 °C to 550 °C, with oxygen to biomass (O/B) ratios varying from 0.05 to 0.30. The process efficiently converts this low-cost, renewable biomass into valuable products and aims to reduce energy intake during pyrolysis while maximizing the yield of useful products. The optimal conditions were identified at an O/B ratio of 0.1 and a temperature of 500 °C, resulting in a product distribution of 26.4 wt% for bio-oil, 20.5 wt% for bio-char, and remaining pyro-gas. The bio-oil was rich in oxygenated compounds, while the bio-char demonstrated a high surface area and nutrient content, making it suitable for various applications. The pyro-gas primarily consisted of carbon monoxide and carbon dioxide, with moderate amounts of hydrogen and methane. This study supports the benefits of oxidative pyrolysis for waste utilization through a self-heat generation approach by partial feed combustion providing the internal heat required for the process initiation that can be aligned with the principles of a circular economy to achieve environmental responsibility. Full article
(This article belongs to the Special Issue Biofuels and Bioenergy: New Advances and Challenges)
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<p>Illustration of the experimental set-up as a self-heat generation by partial feed combustion provides the internal heat required for the process initiation.</p>
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<p>TG and DTG curve of banana waste pyrolysis.</p>
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<p>Banana mix waste fluidized bed pyrolysis product yield distribution with varying processing temperatures.</p>
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<p>Effect of ER ratio on banana mix waste pyrolysis products in a fluidised bed reactor at a temperature of 500 °C.</p>
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<p>A relative percentage of the different component groups in bio-oil derived from banana mix waste obtained at 500 °C.</p>
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<p>The concentration variation of pyrolytic gas components over 60 min after stable operation (20 min).</p>
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26 pages, 4650 KiB  
Article
Hydrodeoxygenation of Phenolic Compounds and Lignin Bio-Oil Surrogate Mixture over Ni/BEA Zeolite Catalyst and Investigation of Its Deactivation
by Antigoni G. Margellou, Foteini F. Zormpa, Dimitrios Karfaridis, Stamatia A. Karakoulia and Konstantinos S. Triantafyllidis
Catalysts 2025, 15(1), 48; https://doi.org/10.3390/catal15010048 - 7 Jan 2025
Viewed by 542
Abstract
Lignin is one of the main structural components of lignocellulosic biomass and can be utilized to produce phenolic compounds that can be converted downstream to cycloalkanes and aromatics, which are useful as drop-in road or aviation biofuels. Within this study, the hydrodeoxygenation of [...] Read more.
Lignin is one of the main structural components of lignocellulosic biomass and can be utilized to produce phenolic compounds that can be converted downstream to cycloalkanes and aromatics, which are useful as drop-in road or aviation biofuels. Within this study, the hydrodeoxygenation of model phenolic/aromatic compounds and surrogate mixture simulating the light fraction of lignin fast-pyrolysis bio-oil was performed under mild reaction conditions. Ni/BEA zeolite was selected as a catalyst to investigate the conversion and the product selectivity of alkyl phenols (phenol, catechol, cresols), methoxy-phenols (guaiacol, syringol, creosol), aromatics (anisole, 1,2,3-trimethoxybenzene) and dimer (2-phenoxy-1-phenyl ethanol) compounds towards (alkyl)cycloalkanes. The hydrodeoxygenation of a surrogate mixture of eleven phenolic and aromatic compounds was then studied by investigating the effect of reaction conditions (temperature, time, H2 pressure, surrogate mixture concentration, and catalyst-to-feed ratio). The conversion of model compounds was in the range of 80–100%, towards a 37–81% (alkyl)cycloalkane yield, being strongly dependent on the complexity/side-chain group of the phenolic/aromatic ring. Regarding the hydrodeoxygenation of the surrogate mixture, 59–100% conversion was achieved, with up to a 72% yield of C6–C9 cycloalkanes. Characterization of spent catalysts showed that the hydrodeoxygenation of surrogate mixture led to carbonaceous depositions on the catalyst, which can be limited under lower temperatures and longer reaction conditions, while after regeneration, the physicochemical properties of catalysts can be partially recovered. Full article
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<p>Hydrodeoxygenation of hydroxy and alkyl-substituted phenols at 220 °C, 1 h, 50 bar H<sub>2</sub>, 10% Ni/BETA (12.5), C/F = 0.2.</p>
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<p>Hydrodeoxygenation of alkoxy phenols/benzene and dimer at 220 °C, 1 h, 50 bar H<sub>2</sub>, 10% Ni/BETA (12.5), C/F = 0.2.</p>
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<p>Proposed hydrodeoxygenation pathways of 2-phenoxy-1-phenyl ethanol. Compounds in red frames were identified via GC-MS analysis; the red wave line in the reactant compound indicates the main linkage cleaved during hydrodeoxygenation.</p>
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<p>Effect of different reaction conditions on the hydrodeoxygenation of the surrogate mixture over 10%Ni/BETA (12.5). The basic conditions were: 220 °C, 1 h, 50 bar H<sub>2</sub>, 50 wt.% surrogate in hexadecane, C/F = 0.2, stirring rate = 400 rpm.</p>
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<p>Effect of different reaction conditions on the product distribution of surrogate mixture hydrodeoxygenation over 10%Ni/BETA (12.5). The basic conditions were: 220 °C, 1 h, 50 bar H<sub>2</sub>, 50 wt.% surrogate in hexadecane, C/F = 0.2, stirring rate = 400 rpm.</p>
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<p>Effect of different reaction conditions on carbon number distributions of non-oxygenated compounds identified in the hydrodeoxygenation of the surrogate mixture over 10%Ni/BETA (12.5).</p>
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<p>Effect of different reaction conditions on carbon (elemental analysis)/coke (TGA) depositions on 10%Ni/BETA (12.5).</p>
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<p>XRD analysis of selected spent and regenerated catalysts recovered from the experiments at (<b>a</b>) 320 °C, 1 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 400 rpm, (<b>b</b>) 220 °C, 3 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 400 rpm and (<b>c</b>) 220 °C, 1 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 600 rpm.</p>
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<p>XPS spectra of (<b>a</b>) fresh, (<b>b</b>) used, and (<b>c</b>) regenerated catalyst from the experiment at 220 °C, 1 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50%, 600 rpm. Left: wide spectra, middle: nickel region, and right: carbon region.</p>
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<p>N<sub>2</sub> physisorption isotherms and BJH pore-size distributions of selected spent and regenerated catalysts recovered from the experiments at (<b>a</b>) 320 °C, 1 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 400 rpm, (<b>b</b>) 220 °C, 3 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 400 rpm and (<b>c</b>) 220 °C, 1 h, 50 bar H<sub>2</sub>, C/F = 0.2, 50% surrogate in hexadecane, 600 rpm.</p>
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18 pages, 3031 KiB  
Article
Surfactant-Enhanced Enzymatic Hydrolysis of Eucalyptus Kraft Pulp: The Interrelationship Between Lignin Reduction and Sugar Recovery
by Jesús J. Ascencio, Leticia S. Magalhães, Fabrício B. Ferreira, Otto Heinz, André Ferraz and Anuj K. Chandel
Catalysts 2025, 15(1), 47; https://doi.org/10.3390/catal15010047 - 7 Jan 2025
Viewed by 498
Abstract
This study examines the effect of surfactant-enhanced enzymatic hydrolysis on eucalyptus Kraft pulps produced under high (CPHA) and mild (CPMA) alkali conditions to optimize saccharification and sugar yield. Compositional analysis revealed an increase in glucan content, from 40% in untreated eucalyptus to 70.1% [...] Read more.
This study examines the effect of surfactant-enhanced enzymatic hydrolysis on eucalyptus Kraft pulps produced under high (CPHA) and mild (CPMA) alkali conditions to optimize saccharification and sugar yield. Compositional analysis revealed an increase in glucan content, from 40% in untreated eucalyptus to 70.1% in CPHA. Both pulps were hydrolyzed using Cellic® CTec3 HS enzyme (Novozymes). A 22 factorial design revealed maximum sugar conversion (~100%) with enzyme loading of 10 FPU/g carbohydrate and 10% (w/v) solids. Tween 20 significantly boosted hydrolysis in CPMA, increasing reducing sugars from 42 g/L to 65 g/L and efficiency from 59.6% to 92.2% within 6 h. By contrast, Tween 80 and PEG 400 showed limited effects on CPMA. Surfactants mitigated lignin–enzyme interactions, especially in CPMA, as higher lignin content restricted hydrolysis efficiency. Phenolic content in the hydrolysates revealed that Tween 80 increased the release of inhibitory compounds, while Tween 20 kept phenolic levels lower. Overall, Tween 20 improved sugar yields and hydrolysis efficiency even with moderate lignin removal during kraft pretreatment, highlighting its potential to reduce enzyme loading and costs in industrial biorefineries. This study underscores the importance of optimizing surfactant selection based on biomass composition for effective enzymatic hydrolysis for cellulosic sugar recovery. Full article
(This article belongs to the Section Biomass Catalysis)
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<p>Surface morphology at 1 mm and 100 µm magnifications by SEM, showing fiber structural differences with orange arrows and circles: (<b>A</b>,<b>B</b>) untreated eucalyptus; (<b>C</b>,<b>D</b>) cellulose pulps from mild alkali (CPMA) concentration; (<b>E</b>,<b>F</b>) cellulose pulps from high alkali (CPHA) concentration.</p>
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<p>Pareto charts of standardized effects on enzymatic hydrolysis efficiency for CPMA and CPHA.</p>
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<p>Effect of enzyme loading and total solids on enzymatic hydrolysis efficiency of eucalyptus pulps: (<b>A</b>,<b>B</b>) surface and contour plots for CPMA; (<b>C</b>,<b>D</b>) surface and contour plots for CPHA.</p>
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<p>Comparative analysis of time course of reducing sugar production, enzymatic hydrolysis efficiency, and productivity over time with different non-ionic surfactant additives in cellulose pulps hydrolysis: (<b>A</b>,<b>B</b>) CPMA; (<b>C</b>,<b>D</b>) CPHA.</p>
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<p>Comparative analysis of sugar production by HPLC and total phenolic content (TPC) in CPMA and CPHA cellulosic hydrolysates with surfactant additives after 24 h. Photos of the hydrolysates were taken after static incubation to allow solids to precipitate.</p>
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27 pages, 1438 KiB  
Review
Metal-Based Catalysts in Biomass Transformation: From Plant Feedstocks to Renewable Fuels and Chemicals
by Muhammad Saeed Akhtar, Muhammad Tahir Naseem, Sajid Ali and Wajid Zaman
Catalysts 2025, 15(1), 40; https://doi.org/10.3390/catal15010040 - 4 Jan 2025
Viewed by 700
Abstract
The transformation of biomass into renewable fuels and chemicals has gained remarkable attention as a sustainable alternative to fossil-based resources. Metal-based catalysts, encompassing transition and noble metals, are crucial in these transformations as they drive critical reactions, such as hydrodeoxygenation, hydrogenation, and reforming. [...] Read more.
The transformation of biomass into renewable fuels and chemicals has gained remarkable attention as a sustainable alternative to fossil-based resources. Metal-based catalysts, encompassing transition and noble metals, are crucial in these transformations as they drive critical reactions, such as hydrodeoxygenation, hydrogenation, and reforming. Transition metals, including nickel, cobalt, and iron, provide cost-effective solutions for large-scale processes, while noble metals, such as platinum and palladium, exhibit superior activity and selectivity for specific reactions. Catalytic advancements, including the development of hybrid and bimetallic systems, have further improved the efficiency, stability, and scalability of biomass transformation processes. This review highlights the catalytic upgrading of lignocellulosic, algal, and waste biomass into high-value platform chemicals, biofuels, and biopolymers, with a focus on processes, such as Fischer–Tropsch synthesis, aqueous-phase reforming, and catalytic cracking. Key challenges, including catalyst deactivation, economic feasibility, and environmental sustainability, are examined alongside emerging solutions, like AI-driven catalyst design and lifecycle analysis. By addressing these challenges and leveraging innovative technologies, metal-based catalysis can accelerate the transition to a circular bioeconomy, supporting global efforts to combat climate change and reduce fossil fuel dependence. Full article
(This article belongs to the Special Issue Catalytic Conversion of Biomass to Chemicals)
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<p>Mechanisms of Metal Catalysts in Biomass Transformation.</p>
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<p>Catalytic Pathways in Biomass Conversion.</p>
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<p>Catalytic Cracking Process in Biorefineries.</p>
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28 pages, 1132 KiB  
Review
Theory and Practice of Burning Solid Biofuels in Low-Power Heating Devices
by Małgorzata Dula and Artur Kraszkiewicz
Energies 2025, 18(1), 182; https://doi.org/10.3390/en18010182 - 3 Jan 2025
Viewed by 533
Abstract
Combustion is the most advanced and proven method on the market for using agricultural by-product residues and waste from the agri-food industry. Currently, a wide range of combustion technologies is used to produce heat and electricity in low-power heating devices (>50 kW) using [...] Read more.
Combustion is the most advanced and proven method on the market for using agricultural by-product residues and waste from the agri-food industry. Currently, a wide range of combustion technologies is used to produce heat and electricity in low-power heating devices (>50 kW) using various types of biofuels from biomass (woody biomass, herbaceous biomass, waste and residues from the agri-food industry). Combustion of biomass fuels, especially those of wood origin, causes lower carbon dioxide (CO2) and sulfur oxides (SOx) emissions into the atmosphere compared to coal combustion. The growing interest in solid biofuels has contributed to intensive activities on improving the combustion process and energy devices enabling effective and economic conversion of chemical energy contained in biomass into other usable forms such as heat, electricity. Having good quality fuel, it is necessary to ensure an appropriate, clean combustion technique, which allows to achieve the highest thermal efficiency of the heating device and at the same time the lowest emission of pollutants. The article presents issues related to the theory, characteristics of the combustion process and problems related to the formation of harmful chemical compounds nitrogen oxides (NOx), SOx, carbon monoxide (CO), particulate matter (PM) emitted to the atmosphere during the combustion process in low-power heating devices. The analysis indicates the possibility of minimizing undesirable phenomena during the combustion of these biofuels related to ash sintering, the formation of deposits, corrosion and improving the amount of condensable solid particles formed and therefore reducing the emission of gaseous products to the environment. Full article
(This article belongs to the Special Issue Advanced Combustion Technologies and Emission Control)
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<p>Formation mechanism of nitrogen oxides. Own study, based on [<a href="#B71-energies-18-00182" class="html-bibr">71</a>].</p>
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<p>Synergy effects between co-burned fuels [<a href="#B117-energies-18-00182" class="html-bibr">117</a>].</p>
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