Pub Date : 2025-11-24DOI: 10.1016/j.supflu.2025.106851
Erxing Ren , Xiaoyu Yao , Zhi Yang , Qiaoyan Dong , Jun Shen
Liquid oxygen/liquid methane rockets are currently one of the most mature technologies among heavy-lift launch vehicles. However, the combustion of methane and oxygen is a complex transcritical process. The fluid crosses the Widom line can lead to heat transfer deterioration, thereby affecting the stability of combustion. This paper uses molecular dynamics (MD) simulations to calculate the Widom line of the methane-oxygen binary mixture with component changes and investigates the changes in microscopic structure of the mixture as it crosses the Widom line. The results of radial distribution function (RDF) indicate that the second peak exists in the liquid-like region, and when the binary mixture crosses the Widom line into the gas-like region, the second peaks of both components disappear simultaneously. This research findings provide a method for identifying the Widom line of binary mixtures and assist in engineering the identification of regions where heat transfer deterioration occurs during supercritical processes.
{"title":"Molecular dynamics study on the Widom Line of binary mixture of methane and oxygen system","authors":"Erxing Ren , Xiaoyu Yao , Zhi Yang , Qiaoyan Dong , Jun Shen","doi":"10.1016/j.supflu.2025.106851","DOIUrl":"10.1016/j.supflu.2025.106851","url":null,"abstract":"<div><div>Liquid oxygen/liquid methane rockets are currently one of the most mature technologies among heavy-lift launch vehicles. However, the combustion of methane and oxygen is a complex transcritical process. The fluid crosses the Widom line can lead to heat transfer deterioration, thereby affecting the stability of combustion. This paper uses molecular dynamics (MD) simulations to calculate the Widom line of the methane-oxygen binary mixture with component changes and investigates the changes in microscopic structure of the mixture as it crosses the Widom line. The results of radial distribution function (RDF) indicate that the second peak exists in the liquid-like region, and when the binary mixture crosses the Widom line into the gas-like region, the second peaks of both components disappear simultaneously. This research findings provide a method for identifying the Widom line of binary mixtures and assist in engineering the identification of regions where heat transfer deterioration occurs during supercritical processes.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106851"},"PeriodicalIF":4.4,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145592957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Valorizing wine industry by-products like Tannat grape seeds offers a sustainable path to recover high-value bioactives and reduce environmental impact. This study aims to achieve their comprehensive value-added utilization by comparing extraction methods to obtain bioactive compounds of interest and by characterizing the functional properties of the solid residue remaining after extraction. Three extraction techniques were applied: the conventional Soxhlet method, using either absolute ethanol or hexane, supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE), assessing the effects of temperature and ethanol concentration on extraction yield and antioxidant properties. Under optimal conditions (80 °C and 67 % ethanol), PLE achieved a higher yield than the conventional method, with elevated α-tocopherol content (844.4 ± 15.3 mg/kg mg/kg) and a lipid fraction dominated by polyunsaturated fatty acids, primarily linoleic acid. This fraction showed significant antioxidant capacity as determined by the ABTS and ORAC-FL assays and, in an accelerated oxidation test, increased the induction period of sunflower oil in a concentration-dependent manner, with an effect comparable to that of the synthetic antioxidant BHA. The solid residue generated after PLE was evaluated for its techno-functional properties. It exhibited higher water-holding capacity compared with untreated ground seeds, possibly due to its higher relative fiber content and structural changes induced by processing. Furthermore, the residue retained residual bioactive properties, highlighting its potential as a functional ingredient. Overall, these results support the use of PLE as an efficient strategy for the integral and sustainable utilization of Tannat grape seeds.
{"title":"Towards a sustainable utilization of Tannat grape seeds: Extraction of bioactive compounds through green technologies and waste revalorization","authors":"Carla Bonifacino , Cecilia Dauber , Analía Martínez , Florencia Tourné , Bruno Irigaray , Ignacio Vieitez , Cecilia Abirached","doi":"10.1016/j.supflu.2025.106850","DOIUrl":"10.1016/j.supflu.2025.106850","url":null,"abstract":"<div><div>Valorizing wine industry by-products like Tannat grape seeds offers a sustainable path to recover high-value bioactives and reduce environmental impact. This study aims to achieve their comprehensive value-added utilization by comparing extraction methods to obtain bioactive compounds of interest and by characterizing the functional properties of the solid residue remaining after extraction. Three extraction techniques were applied: the conventional Soxhlet method, using either absolute ethanol or hexane, supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE), assessing the effects of temperature and ethanol concentration on extraction yield and antioxidant properties. Under optimal conditions (80 °C and 67 % ethanol), PLE achieved a higher yield than the conventional method, with elevated α-tocopherol content (844.4 ± 15.3 mg/kg mg/kg) and a lipid fraction dominated by polyunsaturated fatty acids, primarily linoleic acid. This fraction showed significant antioxidant capacity as determined by the ABTS and ORAC-FL assays and, in an accelerated oxidation test, increased the induction period of sunflower oil in a concentration-dependent manner, with an effect comparable to that of the synthetic antioxidant BHA. The solid residue generated after PLE was evaluated for its techno-functional properties. It exhibited higher water-holding capacity compared with untreated ground seeds, possibly due to its higher relative fiber content and structural changes induced by processing. Furthermore, the residue retained residual bioactive properties, highlighting its potential as a functional ingredient. Overall, these results support the use of PLE as an efficient strategy for the integral and sustainable utilization of Tannat grape seeds.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106850"},"PeriodicalIF":4.4,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The reliance on fossil fuels has led to significant environmental issues, including greenhouse gas emissions and climate change. As global energy demand increases, the need for sustainable alternatives becomes crucial. Microalgae have emerged as a renewable and carbon-neutral source for hydrogen production through supercritical water gasification (SCWG) due to their rapid growth, minimal land requirements, and beneficial biochemical properties. This study examines hydrogen production from Dunaliella salina, Spirulina platensis, and Chlorella vulgaris through SCWG at 400°C, 242 bar, and a 45 min residence time. A 4 wt% glycerol/methanol mixture, simulating biodiesel byproducts, was used as the reaction medium with and without a 10 wt% cobalt catalyst at feed concentrations of 5, 10, and 15 wt%. Among microalgae, Dunaliella salina yielded the highest hydrogen mole fraction, reaching 65 % at 10 wt% feed concentration. The cobalt catalyst significantly enhanced hydrogen production (e.g., Dunaliella salina from 38.8 % to 58.5 % H2 at 15 wt%), hydrogen selectivity (max 50.43 %), and gasification efficiency (max 14.5 %). Moreover, replacing deionized water with a glycerol/methanol medium proved highly beneficial. This substitution substantially increased hydrogen production, alongside notable improvements in selectivity and gasification efficiency, highlighting the synergistic effect of biodiesel byproducts as a reactive solvent in SCWG. These findings underscore the dual benefit of employing biodiesel-derived reaction media and cobalt catalysis in simultaneously enhancing the efficiency and performance of the gasification process. Among the studied species, Dunaliella salina showed the highest potential for clean hydrogen generation, confirming its promise as a strategic microalgal feedstock for future sustainable energy systems.
{"title":"Sustainable hydrogen production via catalytic supercritical water gasification of microalgae biomass in glycerol-methanol mixture","authors":"Ghazal Azadi, Arash Hedayati, Omid Tavakoli, Fatemeh Saberi","doi":"10.1016/j.supflu.2025.106849","DOIUrl":"10.1016/j.supflu.2025.106849","url":null,"abstract":"<div><div>The reliance on fossil fuels has led to significant environmental issues, including greenhouse gas emissions and climate change. As global energy demand increases, the need for sustainable alternatives becomes crucial. Microalgae have emerged as a renewable and carbon-neutral source for hydrogen production through supercritical water gasification (SCWG) due to their rapid growth, minimal land requirements, and beneficial biochemical properties. This study examines hydrogen production from <em>Dunaliella salina</em>, <em>Spirulina platensis</em>, and <em>Chlorella vulgaris</em> through SCWG at 400°C, 242 bar, and a 45 min residence time. A 4 wt% glycerol/methanol mixture, simulating biodiesel byproducts, was used as the reaction medium with and without a 10 wt% cobalt catalyst at feed concentrations of 5, 10, and 15 wt%. Among microalgae, <em>Dunaliella salina</em> yielded the highest hydrogen mole fraction, reaching 65 % at 10 wt% feed concentration. The cobalt catalyst significantly enhanced hydrogen production (e.g., <em>Dunaliella salina</em> from 38.8 % to 58.5 % H<sub>2</sub> at 15 wt%), hydrogen selectivity (max 50.43 %), and gasification efficiency (max 14.5 %). Moreover, replacing deionized water with a glycerol/methanol medium proved highly beneficial. This substitution substantially increased hydrogen production, alongside notable improvements in selectivity and gasification efficiency, highlighting the synergistic effect of biodiesel byproducts as a reactive solvent in SCWG. These findings underscore the dual benefit of employing biodiesel-derived reaction media and cobalt catalysis in simultaneously enhancing the efficiency and performance of the gasification process. Among the studied species, <em>Dunaliella salina</em> showed the highest potential for clean hydrogen generation, confirming its promise as a strategic microalgal feedstock for future sustainable energy systems.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106849"},"PeriodicalIF":4.4,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-23DOI: 10.1016/j.supflu.2025.106848
Paul Zvawanda , Paramespri Naidoo , Wayne M. Nelson , Kuveneshan Moodley
Hydrogen production via natural gas reforming with integrated carbon capture technology is a viable option as a cleaner fuel source. The solubility of carbon dioxide, methane, and hydrogen into quinaldine (a liquid organic hydrogen carrier, with a hydrogen carrying capacity of 6.6 wt%) is explored for its potential in a direct hydrogen capture application. This study investigated the phase equilibria data for carbon dioxide/methane/hydrogen + 2-methyl-quinoline (quinaldine) over a temperature range of 263–393 K and pressures up to 2.6 MPa. Experiments were conducted using a static synthetic visual apparatus. Validation of the experimental technique was performed through the measurement of vapour-liquid equilibrium data for the carbon dioxide + methanol/n-dodecane/triethylene-glycol test systems from 298 to 353 K and the hydrogen + cyclohexane test system at 303 K. Generally good comparisons were observed between the reported literature data and the data of this work. The data were regressed in Aspen Plus V14 using the Peng-Robinson equation of state. Such information aids in generating a database for phase equilibrium data related to carbon capture and energy storage materials, which forms the backbone for the design of separation and purification units.
{"title":"Phase equilibrium data for carbon dioxide/methane/hydrogen + 2-methyl quinoline from T = 263–393 K and P up to 2.6 MPa","authors":"Paul Zvawanda , Paramespri Naidoo , Wayne M. Nelson , Kuveneshan Moodley","doi":"10.1016/j.supflu.2025.106848","DOIUrl":"10.1016/j.supflu.2025.106848","url":null,"abstract":"<div><div>Hydrogen production via natural gas reforming with integrated carbon capture technology is a viable option as a cleaner fuel source. The solubility of carbon dioxide, methane, and hydrogen into quinaldine (a liquid organic hydrogen carrier, with a hydrogen carrying capacity of 6.6 wt%) is explored for its potential in a direct hydrogen capture application. This study investigated the phase equilibria data for carbon dioxide/methane/hydrogen + 2-methyl-quinoline (quinaldine) over a temperature range of 263–393 K and pressures up to 2.6 MPa. Experiments were conducted using a static synthetic visual apparatus. Validation of the experimental technique was performed through the measurement of vapour-liquid equilibrium data for the carbon dioxide + methanol/n-dodecane/triethylene-glycol test systems from 298 to 353 K and the hydrogen + cyclohexane test system at 303 K. Generally good comparisons were observed between the reported literature data and the data of this work. The data were regressed in Aspen Plus V14 using the Peng-Robinson equation of state. Such information aids in generating a database for phase equilibrium data related to carbon capture and energy storage materials, which forms the backbone for the design of separation and purification units.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106848"},"PeriodicalIF":4.4,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-22DOI: 10.1016/j.supflu.2025.106838
Jian Cardenas, Song Zhao, Isabelle Raspo, Guillaume Chiavassa, Pierre Boivin
This article develops two algorithms for the thermal Lattice Boltzmann Method (LBM) to simulate supercritical fluid dynamics using real-fluid thermodynamics. The first algorithm employs a compressible formulation (LBM-C), while the second is based on a Low Mach Number approximation (LBM-LMN) to enhance computational efficiency without compromising physical fidelity. Both approaches use a conservative scheme compatible with cubic equations of state (EOS), enabling accurate representation of non-ideal behaviors under supercritical conditions and ensuring mass, momentum, and energy conservation. Validation on canonical supercritical flow benchmarks demonstrates that the LBM-LMN approach achieves accuracy comparable to the compressible formulation while reducing the overall computational time by a factor of about 15, as quantified by the RTTS parameter.
{"title":"Lattice-Boltzmann methods for supercritical fluids flows","authors":"Jian Cardenas, Song Zhao, Isabelle Raspo, Guillaume Chiavassa, Pierre Boivin","doi":"10.1016/j.supflu.2025.106838","DOIUrl":"10.1016/j.supflu.2025.106838","url":null,"abstract":"<div><div>This article develops two algorithms for the thermal Lattice Boltzmann Method (LBM) to simulate supercritical fluid dynamics using real-fluid thermodynamics. The first algorithm employs a compressible formulation (LBM-C), while the second is based on a Low Mach Number approximation (LBM-LMN) to enhance computational efficiency without compromising physical fidelity. Both approaches use a conservative scheme compatible with cubic equations of state (EOS), enabling accurate representation of non-ideal behaviors under supercritical conditions and ensuring mass, momentum, and energy conservation. Validation on canonical supercritical flow benchmarks demonstrates that the LBM-LMN approach achieves accuracy comparable to the compressible formulation while reducing the overall computational time by a factor of about 15, as quantified by the RTTS parameter.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106838"},"PeriodicalIF":4.4,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-21DOI: 10.1016/j.supflu.2025.106845
Victor M. Amador-Luna , Lidia Montero , Carlos Pajuelo , Clovis Antonio Balbinot Filho , Marcelo Lanza , Sandra Regina Salvador Ferreira , Elena Ibáñez , Miguel Herrero
This study focused on optimizing a Natural Deep Eutectic Solvent (NADES)-based extraction for recovering bioactive compounds, particularly phenolic and terpenic compounds, from orange by-products, aimed at neuroprotection. CO₂-assisted pressurized NADES extraction enhanced both yield and bioactivity compared to more conventional approaches. After the extraction, the encapsulation of the extract obtained with pressurized betaine:glycerol (Bet:Gly, 1:2) was optimized through a Box-Behnken design using soy phosphatidylcholine as encapsulating agent; optimum process conditions were: concentration of the extract, 4199 ppm; orbital agitation time, 99.1 min; temperature, 55.1 °C. The encapsulation process allowed retaining 66 %, 34 %, and 80 % of carotenoids, terpenes, and phenolic compounds, respectively. Once the optimum conditions were stablished, sunflower lecithin was also tested as a new encapsulating agent. The use of sunflower lecithin improved terpene and phenolic compounds encapsulation by 18 and 15 %, respectively, significantly enhancing potential neuroprotective capacity. Moreover, the chemical characterization of the extract further supported these findings. Stability tests revealed that pressurized NADES extracts maintained their bioactivity for 15 days, whereas the microencapsulation process improved stability and preserved bioactivity for over four months. Despite some losses in terpene and phenolic content under accelerated conditions, microencapsulation significantly extended the shelf-life and functionality of the bioactive compounds.
{"title":"New approaches for improving bioactivity and stability of natural extracts: CO2-assisted compressed NADES and microencapsulation","authors":"Victor M. Amador-Luna , Lidia Montero , Carlos Pajuelo , Clovis Antonio Balbinot Filho , Marcelo Lanza , Sandra Regina Salvador Ferreira , Elena Ibáñez , Miguel Herrero","doi":"10.1016/j.supflu.2025.106845","DOIUrl":"10.1016/j.supflu.2025.106845","url":null,"abstract":"<div><div>This study focused on optimizing a Natural Deep Eutectic Solvent (NADES)-based extraction for recovering bioactive compounds, particularly phenolic and terpenic compounds, from orange by-products, aimed at neuroprotection. CO₂-assisted pressurized NADES extraction enhanced both yield and bioactivity compared to more conventional approaches. After the extraction, the encapsulation of the extract obtained with pressurized betaine:glycerol (Bet:Gly, 1:2) was optimized through a Box-Behnken design using soy phosphatidylcholine as encapsulating agent; optimum process conditions were: concentration of the extract, 4199 ppm; orbital agitation time, 99.1 min; temperature, 55.1 °C. The encapsulation process allowed retaining 66 %, 34 %, and 80 % of carotenoids, terpenes, and phenolic compounds, respectively. Once the optimum conditions were stablished, sunflower lecithin was also tested as a new encapsulating agent. The use of sunflower lecithin improved terpene and phenolic compounds encapsulation by 18 and 15 %, respectively, significantly enhancing potential neuroprotective capacity. Moreover, the chemical characterization of the extract further supported these findings. Stability tests revealed that pressurized NADES extracts maintained their bioactivity for 15 days, whereas the microencapsulation process improved stability and preserved bioactivity for over four months. Despite some losses in terpene and phenolic content under accelerated conditions, microencapsulation significantly extended the shelf-life and functionality of the bioactive compounds.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106845"},"PeriodicalIF":4.4,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145567361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Monometallic (Ni-, Co-, Cu-, and Fe-containing, Me25/Al2O3) and bimetallic (NixCo(50-x)/Al2O3) catalysts were synthesized via precipitation in supercritical carbon dioxide. The catalytic activity of these systems was evaluated in the transfer hydrodechlorination of chlorobenzene, employing supercritical isopropanol as a hydrogen donor, at temperatures ranging from 250 °C to 275 °C. The hydrodechlorination rates for monometallic catalysts followed the order: Ni25/Al2O3 > Co25/Al2O3 > Cu25/Al2O3 > > Fe25/Al2O3. For bimetallic catalysts (NixCo(50-x)/Al2O3), the hydrodechlorination rate increased with increasing nickel content. It was observed that significant coarsening of metal particle crystallites occurred during hydrodechlorination; however, this phenomenon did not demonstrably affect catalyst activity.
{"title":"Transfer hydrodechlorination of chlorobenzene in supercritical isopropanol using monometallic and bimetallic catalysts obtained by precipitation in a supercritical CO2","authors":"A.S. Romanov, N.S. Nesterov, V.P. Pakharukova, D.E. Nasokhov, O.A. Ukhterova, O.N. Martyanov","doi":"10.1016/j.supflu.2025.106846","DOIUrl":"10.1016/j.supflu.2025.106846","url":null,"abstract":"<div><div>Monometallic (Ni-, Co-, Cu-, and Fe-containing, Me25/Al<sub>2</sub>O<sub>3</sub>) and bimetallic (NixCo(50-x)/Al<sub>2</sub>O<sub>3</sub>) catalysts were synthesized via precipitation in supercritical carbon dioxide. The catalytic activity of these systems was evaluated in the transfer hydrodechlorination of chlorobenzene, employing supercritical isopropanol as a hydrogen donor, at temperatures ranging from 250 °C to 275 °C. The hydrodechlorination rates for monometallic catalysts followed the order: Ni25/Al<sub>2</sub>O<sub>3</sub> > Co25/Al<sub>2</sub>O<sub>3</sub> > Cu25/Al<sub>2</sub>O<sub>3</sub> > > Fe25/Al<sub>2</sub>O<sub>3</sub>. For bimetallic catalysts (NixCo(50-x)/Al<sub>2</sub>O<sub>3</sub>), the hydrodechlorination rate increased with increasing nickel content. It was observed that significant coarsening of metal particle crystallites occurred during hydrodechlorination; however, this phenomenon did not demonstrably affect catalyst activity.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"229 ","pages":"Article 106846"},"PeriodicalIF":4.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145559875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyvinyl chloride (PVC) is extensively utilized due to its excellent flame retardancy, aging resistance, and chemical stability. In this work, environmentally friendly supercritical CO2 was employed as a blowing agent for PVC foaming. PVC samples with controlled gelation degrees were prepared by modulating the processing conditions. The results show that gelation degree significantly governs the dissolution and diffusion of CO2 in PVC, consequently dictating foaming behavior and mechanical properties. Elevated gelation degrees promote the development of additional cross-linking points and the formation of stronger network structures, which restrict melt fluidity while substantially increasing both storage and loss moduli, demonstrating enhanced viscoelastic properties of the polymer melt. Notably, as the gelation degree rises from 29.9 % to 74.2 %, the CO2 diffusion coefficient declines from 4.73 × 10−10 m2/s to 9.43 × 10−12 m2/s. This work achieves controlled regulation of the PVC gelation degree to modulate foaming behavior. Specifically, PVC with 63.2 % gelation degree exhibits optimal melt strength coupled with reduced CO2 diffusion rate, yielding the maximum expansion ratio of 11.
{"title":"Effect of gelation degree of PVC on its supercritical CO2 foaming behavior and mechanical properties","authors":"Chenyang Niu, Xuelin Zhang, Xiulu Gao, Qiyuan He, Haonan Chen, Yichong Chen, Weizhen Sun, Ling Zhao, Dongdong Hu","doi":"10.1016/j.supflu.2025.106844","DOIUrl":"10.1016/j.supflu.2025.106844","url":null,"abstract":"<div><div>Polyvinyl chloride (PVC) is extensively utilized due to its excellent flame retardancy, aging resistance, and chemical stability. In this work, environmentally friendly supercritical CO<sub>2</sub> was employed as a blowing agent for PVC foaming. PVC samples with controlled gelation degrees were prepared by modulating the processing conditions. The results show that gelation degree significantly governs the dissolution and diffusion of CO<sub>2</sub> in PVC, consequently dictating foaming behavior and mechanical properties. Elevated gelation degrees promote the development of additional cross-linking points and the formation of stronger network structures, which restrict melt fluidity while substantially increasing both storage and loss moduli, demonstrating enhanced viscoelastic properties of the polymer melt. Notably, as the gelation degree rises from 29.9 % to 74.2 %, the CO<sub>2</sub> diffusion coefficient declines from 4.73 × 10<sup>−10</sup> m<sup>2</sup>/s to 9.43 × 10<sup>−12</sup> m<sup>2</sup>/s. This work achieves controlled regulation of the PVC gelation degree to modulate foaming behavior. Specifically, PVC with 63.2 % gelation degree exhibits optimal melt strength coupled with reduced CO<sub>2</sub> diffusion rate, yielding the maximum expansion ratio of 11.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"230 ","pages":"Article 106844"},"PeriodicalIF":4.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145559876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-14DOI: 10.1016/j.supflu.2025.106843
Ahmed lbrahim, Mohamed Tarek, Zhi-En Xin, Ardila Hayu Tiwikrama
Converting agricultural waste into useful materials through seeking effective and convenient routes is an important step toward shifting to sustainable energy. In this work, a deep eutectic solvent (DES) was prepared by mixing choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and diethylene glycol (DEG) as a hydrogen bond donor (HBD) in a molar ratio of 1:8 to break down rice husk (RH) biomass. The RH was extracted using supercritical CO2 pretreatment at T = 80 °C and 120 °C during the reaction times ranging from (2−24) h to determine the composition of cellulose, hemicellulose and lignin in the RH. The ChCl-DEG achieved successful selective separation of lignin and hemicellulose from lignocellulosic RH biomass with a delignification value of over 66 % at 120 °C after 24 h. The effect of supercritical carbon dioxide (scCO2) was investigated during the fractionation process of the RH. The results show that the use of scCO2 decreased the delignification value, which can be attributed to the disturbance of the hydrogen bonds between the DES and the lignin composition structure, hindering the separation process. Morphological characterization using scanning electron microscopy (SEM) revealed significant changes on the surface of the treated RH, indicating the removal of lignin and hemicellulose from the biomass surface. Overall, the study demonstrates that ChCl-DEG is a promising, adaptable DES for environmentally friendly processing of plant materials.
{"title":"Green sustainable eutectic solvent using supercritical CO2 for extraction composition from rice husk","authors":"Ahmed lbrahim, Mohamed Tarek, Zhi-En Xin, Ardila Hayu Tiwikrama","doi":"10.1016/j.supflu.2025.106843","DOIUrl":"10.1016/j.supflu.2025.106843","url":null,"abstract":"<div><div>Converting agricultural waste into useful materials through seeking effective and convenient routes is an important step toward shifting to sustainable energy. In this work, a deep eutectic solvent (DES) was prepared by mixing choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and diethylene glycol (DEG) as a hydrogen bond donor (HBD) in a molar ratio of 1:8 to break down rice husk (RH) biomass. The RH was extracted using supercritical CO<sub>2</sub> pretreatment at <em>T</em> = 80 °C and 120 °C during the reaction times ranging from (2−24) h to determine the composition of cellulose, hemicellulose and lignin in the RH. The ChCl-DEG achieved successful selective separation of lignin and hemicellulose from lignocellulosic RH biomass with a delignification value of over 66 % at 120 °C after 24 h. The effect of supercritical carbon dioxide (scCO<sub>2</sub>) was investigated during the fractionation process of the RH. The results show that the use of scCO<sub>2</sub> decreased the delignification value, which can be attributed to the disturbance of the hydrogen bonds between the DES and the lignin composition structure, hindering the separation process. Morphological characterization using scanning electron microscopy (SEM) revealed significant changes on the surface of the treated RH, indicating the removal of lignin and hemicellulose from the biomass surface. Overall, the study demonstrates that ChCl-DEG is a promising, adaptable DES for environmentally friendly processing of plant materials.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"229 ","pages":"Article 106843"},"PeriodicalIF":4.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-12DOI: 10.1016/j.supflu.2025.106841
Iván Navarro-Cárdenas, Andreas Kilzer, Eckhard Weidner, Marcus Petermann
Conventional catalytic hydrogenation of oils is essentially constrained by mass-transfer resistance because of the poor solubility of hydrogen in liquid-phase substrates. Supercritical fluids (SCFs) offer a solution by creating a single, homogeneous reaction medium that dissolves both hydrogen and high-molecular-weight oils, thus overcoming the interfacial transport limitations. This review synthesizes several research to establish a unified framework for the supercritical hydrogenation of different feedstocks, including heavy oils, vegetable oils, and emerging streams like bio- and plastic-derived pyrolysis oils. The central goal of this work is to provide a deep understanding of phase behavior which is a critical aspect of the process design, directly influencing reaction rates, selectivity, and overall efficiency. By integrating principles of thermodynamics, heat and mass transfer, catalysis selection, and reactor design, this review provides applicable design metrics for developing a more suitable upgrading technology with higher space yield times for a wide spectrum of complex oils.
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