Artigos de revistas: "Furanic acid"

1

Margellou, Antigoni G., Stylianos A. Torofias, Georgios Iakovou e Konstantinos S. Triantafyllidis. "Valorization of Chlorella Microalgae Residual Biomass via Catalytic Acid Hydrolysis/Dehydration and Hydrogenolysis/Hydrogenation". Catalysts 14, n.º 5 (23 de abril de 2024): 286. http://dx.doi.org/10.3390/catal14050286.

Texto completo da fonte

Resumo:

Microalgal biomass can be utilized for the production of value-added chemicals and fuels. Within this research, Chlorella vulgaris biomass left behind after the extraction of lipids and proteins was converted to valuable sugars, organic acids and furanic compounds via hydrolysis/dehydration using dilute aqueous sulfuric acid as a homogeneous catalyst. Under mild conditions, i.e., low temperature and low sulfuric acid concentration, the main products of hydrolysis/dehydration were monomeric sugars (glucose and xylose) and furanic compounds (HMF, furfural) while under more intense conditions (i.e., higher temperature and higher acid concentration), organic acids (propionic, formic, acetic, succinic, lactic, levulinic) were also produced either directly from sugar conversion or via intermediate furans. As a second valorization approach, the residual microalgal biomass was converted to value-added sugar alcohols (sorbitol, glycerol) via hydrogenation/hydrogenolysis reactions over metallic ruthenium catalysts supported on activated carbons (5%Ru/C). It was also shown that a low concentration of sulfuric acid facilitated the conversion of biomass to sugar alcohols by initiating the hydrolysis of carbohydrates to monomeric sugars. Overall, this work aims to propose valorization pathways for a rarely utilized residual biomass towards useful compounds utilized as platform chemicals and precursors for the production of a wide variety of solvents, polymers, fuels, food ingredients, pharmaceuticals and others.

Estilos ABNT, Harvard, Vancouver, APA, etc.

2

Marshall, Adam, Bo Jiang, Régis M. Gauvin e Christophe M. Thomas. "2,5-Furandicarboxylic Acid: An Intriguing Precursor for Monomer and Polymer Synthesis". Molecules 27, n.º 13 (24 de junho de 2022): 4071. http://dx.doi.org/10.3390/molecules27134071.

Texto completo da fonte

Resumo:

The most versatile furanic building block for chemical and polymer applications is 2,5-furandicarboxylic acid. However, the classical 2,5-furandicarboxylic acid production methodology has been found to have significant drawbacks that hinder industrial-scale production. This review highlights new alternative methods to synthesize 2,5-furandicarboxylic acid that are both more advantageous and attractive than conventional oxidation of 5-hydroxymethylfurfural. This review also focuses on the use of 2,5-furandicarboxylic acid as a polymer precursor and the various potential applications that arise from these furan-based materials.

Estilos ABNT, Harvard, Vancouver, APA, etc.

3

Antunes, Margarida M., Andreia F. Silva, Carolina D. Bernardino, Auguste Fernandes, Filipa Ribeiro e Anabela A. Valente. "Catalytic Transfer Hydrogenation and Acid Reactions of Furfural and 5-(Hydroxymethyl)furfural over Hf-TUD-1 Type Catalysts". Molecules 26, n.º 23 (27 de novembro de 2021): 7203. http://dx.doi.org/10.3390/molecules26237203.

Texto completo da fonte

Resumo:

Heterogeneous catalysis, which has served well the petrochemical industry, may valuably contribute towards a bio-based economy by sustainably enabling selective reactions to renewable chemicals. Carbohydrate-containing matter may be obtained from various widespread sources and selectively converted to furanic platform chemicals: furfural (Fur) and 5-(hydroxymethyl)furfural (Hmf). Valuable bioproducts may be obtained from these aldehydes via catalytic transfer hydrogenation (CTH) using alcohols as H-donors under relatively moderate reaction conditions. Hafnium-containing TUD-1 type catalysts were the first of ordered mesoporous silicates explored for the conversion of Fur and Hmf via CTH/alcohol strategies. The materials promoted CTH and acid reactions leading to the furanic ethers. The bioproducts spectrum was broader for the reaction of Fur than of Hmf. A Fur reaction mechanism based on literature data was discussed and supported by kinetic modelling. The influence of the Hf loading and reaction conditions (catalyst load, type of alcohol H-donor, temperature, initial substrate concentration) on the reaction kinetics was studied. The reaction conditions were optimized to maximize the yields of 2-(alkoxymethyl)furan ethers formed from Fur; up to 63% yield was reached at 88% Fur conversion, 4 h/150 °C, using Hf-TUD-1(75), which was a stable catalyst. The Hf-TUD-1(x) catalysts promoted the selective conversion of Hmf to bis(2-alkoxymethyl)furan; e.g., 96% selectivity at 98% Hmf conversion, 3 h/170 °C for Hf-TUD-1(50).

Estilos ABNT, Harvard, Vancouver, APA, etc.

4

Klushin, V. A., U. A. Chus e Nina Smirnova. "Synthesis of Furanic Polyamides and Composite Coatings from Plant Biomass". Key Engineering Materials 816 (agosto de 2019): 84–89. http://dx.doi.org/10.4028/www.scientific.net/kem.816.84.

Texto completo da fonte

Resumo:

We report, for the first time, the synthesis of polyamide composite coating based on renewable plant biomass sources. 2,5-furandicarboxylic acid (FDCA) was prepared by catalytic oxidation of 5-hydroxymethylfurfural (HMF) obtained by plant biomass conversion. FDCA was used in the synthesis of aliphatic and aromatic furanic polyamides. Two approaches to furanic PAs synthesis have been investigated: (i) synthesis of hexamethylenediamine furanoate salt and its subsequent polycondensation; (ii) synthesis of FDCA dichloride and its subsequent polycondensation in a two-phase aqueous-organic system. The effect of the nature of organic solvent (tetraclormetan, dichloromethane, N-methyl-2-pyrrolidone) and the nature of diamine (hexamethylenediamine and paraphenylenediamine) on the yield and molecular weight of furanic polyamide was studied. The synthesized aliphatic polyamide was used for enamel fabrication. Colloidal graphite and activated carbon obtained from the waste of biomass conversion into HMF were used as fillers. The furanic PA composite coatings on steel provide the lower coefficient of friction and lower wear compared with that of commercial polyamide (PA6) coatings and can be considered as novel promising anti-friction coating materials.

Estilos ABNT, Harvard, Vancouver, APA, etc.

5

Zhang, Bengang, Mathieu Petrissans, Anelie Petrissans, Antonio Pizzi e Baptiste Colin. "Furanic Polymerization Causes the Change, Conservation and Recovery of Thermally-Treated Wood Hydrophobicity before and after Moist Conditions Exposure". Polymers 15, n.º 1 (31 de dezembro de 2022): 221. http://dx.doi.org/10.3390/polym15010221.

Texto completo da fonte

Resumo:

The Whilhelmy method of contact angle, wood thermal properties (TG/DTG), infrared spectroscopy, etc. was used to define the hydrophobicity of heat-treated beech and fir wood at increasing temperatures between 120 °C and 300 °C. By exposure to wet conditions during 1 week, the hydrophobic character obtained by the heat treatment remains constant heat-treated. Heat induced wood hydrophobation, was shown by CP MAS 13C NMR and MALDI ToF mass spectrometry to be mainly caused by furanic moieties produced from heat-induced hemicelluloses degradation. This is caused by the acid environment generated by the hydrolysis of the hemicelluloses acetyl groups. Furfural polymerizes to linear and branched oligomers and finally to water repellent, insoluble furanic resins. The water repellent, black colored, cross-linked polymerized furanic network is present throughout the heat-treated wood. Wood darkening as well as its water repellency due to increasing proportions of black colored furanic resins increase as a function of the increase with treating temperature, becoming particularly evident in the 200 to 300 °C treating temperature range.

Estilos ABNT, Harvard, Vancouver, APA, etc.

6

Gumidyala, Abhishek, Bin Wang e Steven Crossley. "Direct carbon-carbon coupling of furanics with acetic acid over Brønsted zeolites". Science Advances 2, n.º 9 (setembro de 2016): e1601072. http://dx.doi.org/10.1126/sciadv.1601072.

Texto completo da fonte

Resumo:

Effective carbon-carbon coupling of acetic acid to form larger products while minimizing CO2emissions is critical to achieving a step change in efficiency for the production of transportation fuels from sustainable biomass. We report the direct acylation of methylfuran with acetic acid in the presence of water, all of which can be readily produced from biomass. This direct coupling limits unwanted polymerization of furanics while producing acetyl methylfuran. Reaction kinetics and density functional theory calculations illustrate that the calculated apparent barrier for the dehydration of the acid to form surface acyl species is similar to the experimentally measured barrier, implying that this step plays a significant role in determining the net reaction rate. Water inhibits the overall rate, but selectivity to acylated products is not affected. We show that furanic species effectively stabilize the charge of the transition state, therefore lowering the overall activation barrier. These results demonstrate a promising new route to C–C bond–forming reactions for the production of higher-value products from biomass.

Estilos ABNT, Harvard, Vancouver, APA, etc.

7

Salis, Severyn, Nadia Spano, Marco Ciulu, Ignazio Floris, Maria I. Pilo e Gavino Sanna. "Electrochemical Determination of the “Furanic Index” in Honey". Molecules 26, n.º 14 (6 de julho de 2021): 4115. http://dx.doi.org/10.3390/molecules26144115.

Texto completo da fonte

Resumo:

5-(hydroxymethyl)furan-2-carbaldehyde, better known as hydroxymethylfurfural (HMF), is a well-known freshness parameter of honey: although mostly absent in fresh samples, its concentration tends to increase naturally with aging. However, high quantities of HMF are also found in fresh but adulterated samples or honey subjected to thermal or photochemical stresses. In addition, HMF deserves further consideration due to its potential toxic effects on human health. The processes at the origin of HMF formation in honey and in other foods, containing saccharides and proteins—mainly non-enzymatic browning reactions—can also produce other furanic compounds. Among others, 2-furaldehyde (2F) and 2-furoic acid (2FA) are the most abundant in honey, but also their isomers (i.e., 3-furaldehyde, 3F, and 3-furoic acid, 3FA) have been found in it, although in small quantities. A preliminary characterization of HMF, 2F, 2FA, 3F, and 3FA by cyclic voltammetry (CV) led to hypothesizing the possibility of a comprehensive quantitative determination of all these compounds using a simple and accurate square wave voltammetry (SWV) method. Therefore, a new parameter able to provide indications on quality of honey, named “Furanic Index” (FI), was proposed in this contribution, which is based on the simultaneous reduction of all analytes on an Hg electrode to ca. −1.50 V vs. Saturated Calomel Electrode (SCE). The proposed method, validated, and tested on 10 samples of honeys of different botanical origin and age, is fast and accurate, and, in the case of strawberry tree honey (Arbutus unedo), it highlighted the contribution to the FI of the homogentisic acid (HA), i.e., the chemical marker of the floral origin of this honey, which was quantitatively reduced in the working conditions. Excellent agreement between the SWV and Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) data was observed in all samples considered.

Estilos ABNT, Harvard, Vancouver, APA, etc.

8

Holewinski, Adam. "Electro-Oxidative Valorization of Biomass-Derived Furanics". ECS Meeting Abstracts MA2023-02, n.º 27 (22 de dezembro de 2023): 1428. http://dx.doi.org/10.1149/ma2023-02271428mtgabs.

Texto completo da fonte

Resumo:

Electrocatalysis poses many potential advantages for distributed scale biomass valorization. Furanic biomass derivatives such as furfural and 5-hydroxymethylfurfural (HMF) can provide access to a number of value-added chemicals by partial oxidation, including furoic acid, maleic acid, and 2,5-furandicarboxylic acid (FDCA). Here, we have utilized differential reactor studies with online electrochemical mass spectrometry (OLEMS), as well as in-situ attenuated total reflectance surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS), to probe these reaction pathways on various metal electrodes. Experimental insights are combined with computational results to piece together plausible mechanisms. We find tradeoffs between decarbonylation activity and self-assembly of furoate intermediates on late transition metals to be critical selectivity-determining and rate-determining process. We also characterize oxidative dehydrogenation paths for furanic aldehydes, which co-produce (anodic) hydrogen gas. Strategies for improved catalyst design will be discussed.

Estilos ABNT, Harvard, Vancouver, APA, etc.

9

Luo, Kaiju, Yan Wang, Junrong Yu, Jing Zhu e Zuming Hu. "Semi-bio-based aromatic polyamides from 2,5-furandicarboxylic acid: toward high-performance polymers from renewable resources". RSC Advances 6, n.º 90 (2016): 87013–20. http://dx.doi.org/10.1039/c6ra15797a.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

10

Zhao, Deyang, Frederic Delbecq e Christophe Len. "One-Pot FDCA Diester Synthesis from Mucic Acid and Their Solvent-Free Regioselective Polytransesterification for Production of Glycerol-Based Furanic Polyesters". Molecules 24, n.º 6 (15 de março de 2019): 1030. http://dx.doi.org/10.3390/molecules24061030.

Texto completo da fonte

Resumo:

A one pot-two step procedure for the synthesis of diethyl furan-2,5-dicarboxylate (DEFDC) starting from mucic acid without isolation of the intermediate furan dicarboxylic acid (FDCA) was studied. Then, the production of three different kinds of furan-based polyesters— polyethylene-2,5-furan dicarboxylate (PEF), polyhydropropyl-2,5-furan dicarboxylate(PHPF) and polydiglycerol-2,5-furandicarboxylate (PDGF)—was realized through a Co(Ac)2·4H2O catalyzed polytransesterification performed at 160 °C between DEFDC and a defined diol furan-based prepolymer or pure diglycerol. In parallel to polymerization process, an unattended regioselective 1-OH acylation of glycerol by direct microwave-heated FDCA diester transesterification led to the formation of a symmetric prepolymer ready for further polymerization and clearly identified by 2D NMR sequences. Furthermore, the synthesis of a more soluble and hydrophilic diglycerol-based furanic polyester was also achieved. The resulting biobased polymers were characterized by NMR, FT-IR spectroscopy, DSC, TGA and XRD. The morphologies of the resulted polymers were observed by FE-SEM and the purity of the material by EDX.

Estilos ABNT, Harvard, Vancouver, APA, etc.

11

Abdel-Rahman, Mohamed Ali, Saad El-Din Hassan, Amr Fouda, Ahmed A. Radwan, Mohammed G. Barghoth e Salha G. Desouky. "Evaluating the Effect of Lignocellulose-Derived Microbial Inhibitors on the Growth and Lactic Acid Production by Bacillus coagulans Azu-10". Fermentation 7, n.º 1 (27 de janeiro de 2021): 17. http://dx.doi.org/10.3390/fermentation7010017.

Texto completo da fonte

Resumo:

Effective lactic acid (LA) production from lignocellulosic biomass materials is challenged by several limitations related to pentose sugar utilization, inhibitory compounds, and/or fermentation conditions. In this study, a newly isolated Bacillus coagulans strain Azu-10 was obtained and showed homofermentative LA production from xylose with optimal fermentation conditions at 50 °C and pH 7.0. Growth of strain Azu-10 and LA-fermentation efficiency were evaluated in the presence of various lignocellulose-derived inhibitors (furans, carboxylic acids, and phenols) at different concentrations. Furanic lignocellulosic-derived inhibitors were completely detoxified. The strain has exhibited high biomass, complete xylose consumption, and high LA production in the presence of 1.0–4.0 g/L furfural and 1.0–5.0 g/L of hydroxymethyl furfural, separately. Moreover, strain Azu-10 exhibited high LA production in the presence of 5.0–15.0 g/L acetic acid, 5.0 g/L of formic acid, and up to 7.0 g/L of levulinic acid, separately. Besides, for phenolic compounds, p-coumaric acid was most toxic at 1.0 g/L, while syringaldehyde or p-hydroxybenzaldehyde, and vanillin at 1.0 g/L did not inhibit LA fermentation. The present study provides an interesting potential candidate for the thermophilic LA fermentation from lignocellulose-derived substrates at the industrial biorefinery level.

Estilos ABNT, Harvard, Vancouver, APA, etc.

12

Kriechbaum, Ricarda, Oliver Spadiut e Julian Kopp. "Bioconversion of Furanic Compounds by Chlorella vulgaris—Unveiling Biotechnological Potentials". Microorganisms 12, n.º 6 (18 de junho de 2024): 1222. http://dx.doi.org/10.3390/microorganisms12061222.

Texto completo da fonte

Resumo:

Lignocellulosic biomass is abundant on Earth, and there are multiple acidic pretreatment options to separate the cellulose, hemicellulose, and lignin fraction. By doing so, the fermentation inhibitors 5-Hydroxymethylfurfural (HMF) and furfural (FF) are produced in varying concentrations depending on the hydrolyzed substrate. In this study, the impact of these furanic compounds on Chlorella vulgaris growth and photosynthetic activity was analyzed. Both compounds led to a prolonged lag phase in Chlorella vulgaris growth. While the photosynthetic yield Y(II) was not significantly influenced in cultivations containing HMF, FF significantly reduced Y(II). The conversion of 5-Hydroxymethylfurfural and furfural to 5-Hydroxymethyl-2-Furoic Acid and 2-Furoic Acid was observed. In total, 100% of HMF and FF was converted in photoautotrophic and mixotrophic Chlorella vulgaris cultivations. The results demonstrate that Chlorella vulgaris is, as of now, the first known microalgal species converting furanic compounds.

Estilos ABNT, Harvard, Vancouver, APA, etc.

13

Eckardt, Jonas, Thomas Sepperer, Emanuele Cesprini, Primož Šket e Gianluca Tondi. "Comparing Condensed and Hydrolysable Tannins for Mechanical Foaming of Furanic Foams: Synthesis and Characterization". Molecules 28, n.º 6 (20 de março de 2023): 2799. http://dx.doi.org/10.3390/molecules28062799.

Texto completo da fonte

Resumo:

This study examined the potential of hydrolysable tannin in comparison to condensed tannins for the production of furanic foams. The results indicate that chestnut tannin presents lower reactivity and requires a stronger acid for the polymerization. Additionally, foamability and density were found to be dependent on both surfactant concentration and tannin type, allowing lower densities for mimosa tannin and lower thermal conductivities for chestnut-based foams. Mimosa tannin was found to have the highest compression strength, followed by quebracho and chestnut, promising thermal conductivity of around 50 mW/m·K for 300 kg/m3 foams, which suggests that chestnut foams have the potential to performing highly when the density is reduced. Chemical analysis revealed that the methylene moieties of the furanics are non-specific and produces new covalent bonds with nucleophilic substrates: -OH groups and free-positions in the flavonoids. Overall, this study opens new perspectives for the application of hydrolysable tannins in polymer and material science.

Estilos ABNT, Harvard, Vancouver, APA, etc.

14

Vinod, Nivedha, e Saikat Dutta. "Energy Densification of Biomass-Derived Furfurals to Furanic Biofuels by Catalytic Hydrogenation and Hydrodeoxygenation Reactions". Sustainable Chemistry 2, n.º 3 (16 de setembro de 2021): 521–49. http://dx.doi.org/10.3390/suschem2030029.

Texto completo da fonte

Resumo:

The concomitant hydrolysis and dehydration of biomass-derived cellulose and hemicellulose to furfural (FUR) and 5-(hydroxymethyl)furfural (HMF) under acid catalysis allows a dramatic reduction in the oxygen content of the parent sugar molecules with a 100% carbon economy. However, most applications of FUR or HMF necessitate synthetic modifications. Catalytic hydrogenation and hydrogenolysis have been recognized as efficient strategies for the selective deoxygenation and energy densification of biomass-derived furfurals generating water as the sole byproduct. Efficient and eco-friendly catalysts have been developed for the selective hydrogenation of furfurals affording renewable furanic compounds such as 2-methylfuran, 2,5-dimethylfuran and 2-methyltetrahydrofuran with potential applications as biofuel, solvent and chemical feedstock. Hydrogen gas or hydrogen donor molecules, required for the above processes, can also be renewably obtained from biomass using catalytic processes, enabling a circular economy. In this review, the recent developments in the energy densification of furfurals to furanic compounds of commercial significance are elaborated, emphasizing the role of catalyst and the reaction parameters employed. Critical discussion on sourcing hydrogen gas required for the processes, using hydrogen donor solvents, catalyst design and the potential markets of furanic intermediates have been made. Critical evaluations of the accomplishments and challenges in this field are also provided.

Estilos ABNT, Harvard, Vancouver, APA, etc.

15

Azadeh, Elham, Ummi Hani Abdullah, Nurul Basirah Md Ali, Antonio Pizzi, Christine Gerardin-Charbonnier, Philippe Gerardin, Wan Sarah Samiun e Siti Efliza Ashari. "Development of Water Repellent, Non-Friable Tannin-Furanic-Fatty Acids Biofoams". Polymers 14, n.º 22 (19 de novembro de 2022): 5025. http://dx.doi.org/10.3390/polym14225025.

Texto completo da fonte

Resumo:

Tannin-furanic foams were prepared with a good yield using the addition of relatively small proportions of a polyflavonoid tannin extract esterified with either palmitic acid, oleic acid, or lauric acid by its reaction with palmitoyl chloride, oleyl chloride, or lauryl chloride. FTIR analysis allowed us to ascertain the esterification of the tannin, and MALDI-TOF analysis allowed us to identify a number of multi-esterified flavonoid oligomers as well as some linked to residual carbohydrates related to the equally esterified tannin. These foams presented a markedly decreased surface friability or no friability at all, and at densities lower than the standard foam they were compared to. Equally, these experimental foams presented a much-improved water repellence, as indicated by their initial wetting angle, its small variation over time, and its stabilization at a high wetting angle value, while the wetting angle of the standard foam control went to zero very rapidly. This conclusion was supported by the calculation of the total surface energy of their surfaces as well as of their dispersive and polar components.

Estilos ABNT, Harvard, Vancouver, APA, etc.

16

MALLARI, JOHN GODWIN A., e RONNIEL D. MANALO. "Production and characterization of furanic bio-oil from Kawayan kiling (Bambusa vulgaris Schrad ex. Wendl) using molten citric acid in an open system". TAPPI Journal 23, n.º 8 (28 de agosto de 2024): 419–29. http://dx.doi.org/10.32964/tj23.8.419.

Texto completo da fonte

Resumo:

The burning of fossil fuels poses many threats to the environment. These predicaments have led to a continuous search for alternative sources and production of energy, and biomass is considered the most abundant renewable energy source. In this study, the potential to produce furanic bio-oil from the cellulose of Bambusa vulgaris was explored. The proximate chemical analysis of bamboo was determined using TAPPI Standards. Cellulose was isolated through dewaxing, delignification, and alkaline treatments. The furanic bio-oil was produced by mixing cellulose and citric acid in a solvent-free environment. The effects of the digestion time (120 min, 180 min, and 240 min) on the yield and characteristics were determined. The chemical compositions were determined using Fourier transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GCMS). B. vulgaris has the following chemical composition: alpha-cellulose (57.42 ± 0.40), holocellulose (78.84 ± 0.52), lig-nin (28.85 ± 0.17), hot water extractives (3.99 ± 0.08), organic extractives (0.77 ± 0.04), ash (4.67 ± 0.02), and moisture (12.98 ± 0.22). The bio-oil yield was affected by the digestion time. The highest yield was obtained at 180 min, followed by 120 min, and 240 min with 88.59%, 59.28%, and 49.96%, respectively. The peaks in the FTIR spectra corresponded to the compounds determined by the GCMS analysis. The dominant chemicals were furans (29.19%), ketones (26.31%), and carboxylic acids (19.26%). The bio-oil obtained at 180-min digestion time has the following properties: sulfur content (0.032 wt%), kinematic viscosity (1.03 mm2/s), specific gravity (0.925), copper corrosion test (No. 1a), pH (2.753), and water content (not detected). Overall, the obtained values from the properties and chemical characterization can be the basis for investigating its performance for biofuel production and utilization. This study is aligned with the Bamboo Industry’s Strategic Science and Technology Plan for the Philippines to develop other value-added products from bamboo and to achieve Sustainable Development Goal 7 (SDG 7) as determined by the United Nations.

Estilos ABNT, Harvard, Vancouver, APA, etc.

17

Xi, Xuedong, Antonio Pizzi, Hong Lei, Guanben Du, Xiaojian Zhou e Yuying Lin. "Characterization and Preparation of Furanic-Glyoxal Foams". Polymers 12, n.º 3 (20 de março de 2020): 692. http://dx.doi.org/10.3390/polym12030692.

Texto completo da fonte

Resumo:

Synthetic foams have become an essential industrial product for a great variety of applications. Furfuryl alcohol, as a biomass chemical, was reacted with glyoxal at room temperature to prepare furanic-glyoxal rigid foams, and p-toluenesulfonic acid was used as a catalyst to initiate the reaction. Foams with different molar ratios (furfuryl alcohol/glyoxal) were prepared in this work, and uniform cells foams have been obtained. Their compression resistance, 24-h water absorption, density, and other basic properties were tested. Scanning electron microscopy (SEM) was used to observe the cellular morphology of the foams prepared, thermogravimetric analysis (TGA) helped to understand their thermal and combustion properties, and FTIR and Matrix Assisted Laser Desorption Ionisation Time of Flight (MALDI ToF) mass spectroscopy to explain the structure of the resulting foams to clarify the reactions occurring during foaming. The results show that the compression resistance of furanic-glyoxal foams declined as the furfuryl alcohol/glyoxal ratio decreases also. SEM observations revealed that foams with open-cell were obtained when furfuryl alcohol was added in greater amounts, and more closed cell structures were formed as the proportion of glyoxal increased. TGA results showed that the initial ignition temperature of furanic-glyoxal foams is ~200 °C higher than that of wood, and the smaller comprehensive combustion index S (about 0.15 × 10−7 (%2 K−3 min−2)) indicates that the foam burns slowly and has poor flammability, that is, it is not easy to burn.

Estilos ABNT, Harvard, Vancouver, APA, etc.

18

Scapin, Elisandra, e Guenther Carlos Couto Viana. "SYNTHESIS OF 5-HYDROXYMETHYLFURFURAL USING IONIC LIQUID [BMIM][BR] FROM RESIDUAL SOYBEAN AND RICE BIOMASSES". DESAFIOS - Revista Interdisciplinar da Universidade Federal do Tocantins 5, Especial (31 de outubro de 2018): 125–32. http://dx.doi.org/10.20873/uft.2359-3652.2018vol5nespecialp125.

Texto completo da fonte

Resumo:

In contrast to the major environmental impacts of the petrochemical activity, renewable energy sources have been developing, and among this, biomass has stood out. Among the derivatives obtained from biomass, 5-hydroxymethylfurfural (HMF) is considered a key piece in this process. This work aims at the use of rice and soybean hulls for the synthesis of HMF using the ionic liquid [BMIM][Br], aiming the sustainability of this process. Initially the physical pretreatment of biomass followed by acid hydrolysis was carried out. For the synthesis of HMF, 5ml of the hydrolyzate, 2g of ionic liquid at 120ºC, were used in different reaction times. The results were analyzed by infrared spectrophotometry and by high performance liquid chromatography. The best results in both biomasses were after 2h of reaction reaching a concentration of up to 25 times greater when compared to the hydrolyzate, showing the high potential of ionic liquid [BMIM] [Br] in the synthesis of furanic compounds. Keywords: Furanic compounds, raw biomass, ionic liquids.

Estilos ABNT, Harvard, Vancouver, APA, etc.

19

Borrega, Marc, Klaus Niemelä e Herbert Sixta. "Effect of hydrothermal treatment intensity on the formation of degradation products from birchwood". Holzforschung 67, n.º 8 (1 de dezembro de 2013): 871–79. http://dx.doi.org/10.1515/hf-2013-0019.

Texto completo da fonte

Resumo:

Abstract Hydrothermal treatments (HT) of birchwood were conducted at various intensities to extract the hemicelluloses before pulping. The amount of hemicellulose-derived sugars in the hydrolysates, including xylulose, an isomerization product of xylose, reached first a maximum and then decreased with further increasing treatment intensity. The hydrolysates also contained furanic compounds, carboxylic acids, and a large variety of aromatics, the amounts of which were dependent on HT intensity. At high treatment intensities, furfural and acetic acid were the main products quantified. Numerous nonvolatile, low molar mass carboxylic acids were also formed, with 3-deoxypentonic acid being the most abundant. Additionally, almost 40 aromatic monomers and up to 30 dimers were detected. Syringaldehyde was the main monomer and syringaresinol was the main dimer. Some aromatic compounds could not be identified. The complexity of the hydrolysates, particularly after high-intensity HT, requires selective filtration and purification methods before the hydrolysates can be utilized in downstream processes.

Estilos ABNT, Harvard, Vancouver, APA, etc.

20

Chen, Xinyi, Antonio Pizzi, Hisham Essawy, Emmanuel Fredon, Christine Gerardin, Nathanael Guigo e Nicolas Sbirrazzuoli. "Non-Furanic Humins-Based Non-Isocyanate Polyurethane (NIPU) Thermoset Wood Adhesives". Polymers 13, n.º 3 (25 de janeiro de 2021): 372. http://dx.doi.org/10.3390/polym13030372.

Texto completo da fonte

Resumo:

Predominantly non-furanic commercial humins were used to prepare humin-based non-isocyanate polyurethane (NIPU) resins for wood panel adhesives. Pure humin-based NIPU resins and tannin–humin NIPU resins were prepared, the latter to upgrade the humins’ performance. Species in the raw humins and species formed in the NIPU resins were identified by Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI ToF) spectrometry and Fourier Transform Infrared (FTIR). Humins, fulvic acid and derivatives, humic acid and its fragments, some lignans present and furanic oligomers present formed NIPU linkages. Thermomechanical analysis (TMA) showed that as with other biomaterials-based NIPU resins, all these resins also showed two temperature peaks of curing, the first around 130 °C and the second around 220 °C. A decrease in the Modulus of Elasticity (MOE) between the two indicated that the first curing period corresponded to linear growth of the oligomers forming a physical entanglement network. This then disentangled, and the second corresponded to the formation of a chemical cross-linked network. This second peak was more evident for the tannin–humin NIPU resins. All the laboratory particleboard made and tested either bonded with pure humins or with tannin–humin NIPU adhesives satisfied well the internal bond strength requirements of the relevant standard for interior grade panels. The tannin–humin adhesives performed clearly better than the pure humins one.

Estilos ABNT, Harvard, Vancouver, APA, etc.

21

Perestrelo, Rosa, Michael Caldeira, Freddy Rodrigues, Jorge A. M. Pereira e José S. Câmara. "DLLμE/GC-MS as a Powerful Analytical Approach to Establish the Volatilomic Composition of Different Whiskeys". Beverages 8, n.º 3 (1 de setembro de 2022): 53. http://dx.doi.org/10.3390/beverages8030053.

Texto completo da fonte

Resumo:

The volatilomic fingerprint of nine different whiskeys was established using a rapid and sensitive analytical approach based on dispersive liquid–liquid microextraction (DLLμE) followed by gas chromatography mass spectrometry detection (GC-MS) and gas chromatography with flame ionization detection (GC-FID). The influence of the extractor solvent on the extraction efficiency of volatile compounds (VOCs) was evaluated by DLLμE/GC-MS. The highest amounts of VOCs were obtained using 5 mL of sample, dichloromethane as the extractor solvent, and acetone as the disperser solvent. The proposed method showed no matrix effect, good linearity (R2 ≥ 0.993) in the assessed concentration range, recovery (ranging from 70 to 99%, precision (RSD ≤ 15%) and sensitivity (low limits of detection and quantification). A total of 37 VOCs belonging to different biosynthetic pathways including alcohols, esters, acids, carbonyl compounds, furanic compounds and volatile phenols were identified and quantified using DLLμE/GC-MS and DLLμE/GC-FID, respectively. Alcohols (3-methylbutan-1-ol, propan-1-ol), esters (ethyl decanoate, ethyl octanoate, ethyl hexanoate), and acids (decanoic acid, octanoic acid, hexanoic acid) were the most abundant chemical families. The multivariate statistical analysis allowed for the discrimination of whiskeys based on their volatilomic fingerprint, namely octanoic acid, 2-furfural, ethyl octanoate, ethyl hexanoate, acetic acid, ethyl dodecanoate, butan-1-ol, and ethyl decanoate.

Estilos ABNT, Harvard, Vancouver, APA, etc.

22

Espinosa-Mansilla, A., A. Muñoz Dela Peña e F. Salinas. "Semiautomatic Determination of Furanic Aldehydes in Food and Pharmaceutical Samples by a Stopped-Flow Injection Analysis Method". Journal of AOAC INTERNATIONAL 76, n.º 6 (1 de novembro de 1993): 1255–61. http://dx.doi.org/10.1093/jaoac/76.6.1255.

Texto completo da fonte

Resumo:

Abstract A kinetic study of the reactions of 5-hydroxymethyl-2-furfuraldehyde and furfural with 2-thiobarbituric acid (TBA) by a stopped-flow flow injection analysis technique has been undertaken. A semiautomatic method for the analytical determination of these furanic aldehydes is proposed on the basis of reaction with TBA. The proposed stopped-flow method was successfully applied to several commercial pharmaceutical preparations and food samples. The procedure is faster than the earlier procedure for determination of these compounds in foods and pharmaceuticals.

Estilos ABNT, Harvard, Vancouver, APA, etc.

23

Neves, Patrícia, Margarida M. Antunes, Patrícia A. Russo, Joana P. Abrantes, Sérgio Lima, Auguste Fernandes, Martyn Pillinger, Sílvia M. Rocha, Maria F. Ribeiro e Anabela A. Valente. "Production of biomass-derived furanic ethers and levulinate esters using heterogeneous acid catalysts". Green Chemistry 15, n.º 12 (2013): 3367. http://dx.doi.org/10.1039/c3gc41908h.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

24

Krämer, B. K., A. Pickert, C. Hohmann, H. M. Liebich, G. A. Müller, M. Hablitzel e T. Risler. "In Vivo Clearance and Elimination of Nine Marker Substances during Hemofiltration with Different Membranes". International Journal of Artificial Organs 15, n.º 7 (julho de 1992): 408–12. http://dx.doi.org/10.1177/039139889201500706.

Texto completo da fonte

Resumo:

The handling of low, middle and high molecular weight markers was examined in seven stable dialysis patients during hemofiltration with different membranes. Four membranes were examined in a randomized, crossover order (polysulfone, polyamide, AN69 polyacrylonitrile, Asahi polyacrylonitrile) by measuring plasma and dialysate concentrations of phosphate, creatinine, vitamin B12, β2-microglobulin, furanic acid, hippuric acid, retinolbinding protein, alpha-1-antitrypsin, and albumin. Sieving coefficients and plasma clearances of β-microglobulin or retinol-binding protein were markedly or slightly lower during hemofiltration with the Asahi polyacrylonitrile membrane than with the other membranes (highest removal with polysulfone/AN69 polyacrylonitrile membranes). No differences of obvious clinical relevance could be seen between the four membranes. A high β2-microglobulin removal rate might be important to prevent dialysis-associated amyloidosis.

Estilos ABNT, Harvard, Vancouver, APA, etc.

25

Rodríguez-Solana, Raquel, Natacha Coelho, Antonio Santos-Rufo, Sandra Gonçalves, Efrén Pérez-Santín e Anabela Romano. "The Influence of In Vitro Gastrointestinal Digestion on the Chemical Composition and Antioxidant and Enzyme Inhibitory Capacities of Carob Liqueurs Obtained with Different Elaboration Techniques". Antioxidants 8, n.º 11 (16 de novembro de 2019): 563. http://dx.doi.org/10.3390/antiox8110563.

Texto completo da fonte

Resumo:

Carob liqueur is a traditional Mediterranean alcoholic beverage obtained via a wide range of production techniques contributing to the different organoleptic attributes of the final product. The aim of this research was to evaluate the stability of the chemical composition and biological capacities (antioxidant and enzyme inhibition) under in vitro simulated gastrointestinal digestion of liqueurs prepared by flavouring the fig spirit with carob pulp by maceration, distillation, percolation, or aqueous and hydro-alcoholic infusions. For this purpose, the phenolic and furanic compositions, the total phenolic (TPC) and flavonoid (TFC) contents, antioxidant capacity (AC), and enzyme inhibitory potential against acethylcholinesterase, tyrosinase, α-glucosidase and α-amylase enzymes were evaluated. The content of gallic acid decreased after gastrointestinal digestion, while TPC, TFC, and AC significantly increased after each digestion phase. Overall, no significantly different enzyme inhibitions (p < 0.05) were observed among digested liqueurs, with moderate inhibition against acethylcholinesterase and tyrosinase (enzymes related with neurodegenerative diseases), and potent and low inhibitory capacities for α-glucosidase and α-amylase, respectively (ideal conditions employed in antidiabetic therapy). The study indicates that hydro-alcoholic infusion and maceration were the most appropriate methods to obtain liqueurs with higher values of the aforementioned parameters and safe levels of toxic furanics.

Estilos ABNT, Harvard, Vancouver, APA, etc.

26

Yuan, Jian-Ping, e Feng Chen. "Simultaneous separation and determination of sugars, ascorbic acid and furanic compounds by HPLC—dual detection". Food Chemistry 64, n.º 3 (fevereiro de 1999): 423–27. http://dx.doi.org/10.1016/s0308-8146(98)00091-0.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

27

Lima, Sérgio, Margarida M. Antunes, Martyn Pillinger e Anabela A. Valente. "Ionic Liquids as Tools for the Acid-Catalyzed Hydrolysis/Dehydration of Saccharides to Furanic Aldehydes". ChemCatChem 3, n.º 11 (26 de julho de 2011): 1686–706. http://dx.doi.org/10.1002/cctc.201100105.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

28

Schwarz, Mónica, Fabian Weber, Enrique Durán-Guerrero, Remedios Castro, María del Carmen Rodríguez-Dodero, Maria Valme García-Moreno, Peter Winterhalter e Dominico Guillén-Sánchez. "HPLC-DAD-MS and Antioxidant Profile of Fractions from Amontillado Sherry Wine Obtained Using High-Speed Counter-Current Chromatography". Foods 10, n.º 1 (9 de janeiro de 2021): 131. http://dx.doi.org/10.3390/foods10010131.

Texto completo da fonte

Resumo:

In the present work, the polyphenolic profile of a complex matrix such as Amontillado sherry has been processed by means of high-speed counter-current chromatography (HSCCC) and characterized by HPLC-DAD-MS. An Amberlite XAD-7 column was used to obtain the wine extract, and three different biphasic solvent systems were applied for HSCCC separation: MTBE (methyl tert-butyl ether)/n-butanol/acetonitrile/water (1.1/3/1.1/5+0.1% trifluoroacetic acid), MTBE/n-butanol/acetonitrile/water (2/2/1/5), and hexane/ethyl acetate/ethanol/water (1/5/1/5). As a result, 42 phenolic compounds and furanic derivatives have been identified by means of HPLC-DAD-MS, with 11 of them being identified for the first time in Sherry wines: 3-feruloylquinic acid, isovanillin, ethyl vanillate, furoic acid, dihydro-p-coumaric acid, 6-O-feruloylglucose, ethyl gallate, hydroxytyrosol, methyl protocatechuate, homoveratric acid and veratraldehyde. In addition, the antioxidant capacity (ABTS) of the obtained fractions was determined, revealing higher values in those fractions in which compounds such as gallic acid, protocatechuic acid, protocatechualdehyde, trans-caftaric acid, syringic acid, isovanillin or tyrosol, among others, were present. This is the first time that HSCCC has been used to characterize the phenolic composition of Sherry wines.

Estilos ABNT, Harvard, Vancouver, APA, etc.

29

Schwarz, Mónica, Fabian Weber, Enrique Durán-Guerrero, Remedios Castro, María del Carmen Rodríguez-Dodero, Maria Valme García-Moreno, Peter Winterhalter e Dominico Guillén-Sánchez. "HPLC-DAD-MS and Antioxidant Profile of Fractions from Amontillado Sherry Wine Obtained Using High-Speed Counter-Current Chromatography". Foods 10, n.º 1 (9 de janeiro de 2021): 131. http://dx.doi.org/10.3390/foods10010131.

Texto completo da fonte

Resumo:

In the present work, the polyphenolic profile of a complex matrix such as Amontillado sherry has been processed by means of high-speed counter-current chromatography (HSCCC) and characterized by HPLC-DAD-MS. An Amberlite XAD-7 column was used to obtain the wine extract, and three different biphasic solvent systems were applied for HSCCC separation: MTBE (methyl tert-butyl ether)/n-butanol/acetonitrile/water (1.1/3/1.1/5+0.1% trifluoroacetic acid), MTBE/n-butanol/acetonitrile/water (2/2/1/5), and hexane/ethyl acetate/ethanol/water (1/5/1/5). As a result, 42 phenolic compounds and furanic derivatives have been identified by means of HPLC-DAD-MS, with 11 of them being identified for the first time in Sherry wines: 3-feruloylquinic acid, isovanillin, ethyl vanillate, furoic acid, dihydro-p-coumaric acid, 6-O-feruloylglucose, ethyl gallate, hydroxytyrosol, methyl protocatechuate, homoveratric acid and veratraldehyde. In addition, the antioxidant capacity (ABTS) of the obtained fractions was determined, revealing higher values in those fractions in which compounds such as gallic acid, protocatechuic acid, protocatechualdehyde, trans-caftaric acid, syringic acid, isovanillin or tyrosol, among others, were present. This is the first time that HSCCC has been used to characterize the phenolic composition of Sherry wines.

Estilos ABNT, Harvard, Vancouver, APA, etc.

30

Fei, Xuan, Jinggang Wang, Xiaoqin Zhang, Zhen Jia, Yanhua Jiang e Xiaoqing Liu. "Recent Progress on Bio-Based Polyesters Derived from 2,5-Furandicarbonxylic Acid (FDCA)". Polymers 14, n.º 3 (6 de fevereiro de 2022): 625. http://dx.doi.org/10.3390/polym14030625.

Texto completo da fonte

Resumo:

The big challenge today is the upgrading of sustainable materials to replace miscellaneous ones from petroleum resources. Thus, a generic bio-based building block lays the foundation of the huge bio-market to green economy. 2,5-Furandicarboxylic acid (FDCA), a rigid diacid derived from lignocellulose or fructose, represents a great potential as a contender to terephthalic acid (TPA). Recently, studies on the synthesis, modification, and functionalization of bio-based polyesters based on FDCA have attracted widespread attention. To apply furanic polyesters on engineering plastics, packaging materials, electronics, etc., researchers have extended the properties of basic FDCA-based homo-polyesters by directional copolymerization and composite preparation. This review covers the synthesis and performance of polyesters and composites based on FDCA with emphasis bedded on the thermomechanical, crystallization, barrier properties, and biodegradability. Finally, a summary of what has been achieved and the issues waiting to be addressed of FDCA-based polyester materials are suggested.

Estilos ABNT, Harvard, Vancouver, APA, etc.

31

Pickert, A., A. Bäuerle e H. M. Liebich. "Determination of hippuric acid and furanic acid in serum of dialysis patients and control persons by high-performance liquid chromatography". Journal of Chromatography B: Biomedical Sciences and Applications 495 (janeiro de 1989): 95–104. http://dx.doi.org/10.1016/s0378-4347(00)82612-2.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

32

Jiang, Yi, Dina Maniar, Albert J. J. Woortman, Gert O. R. Alberda van Ekenstein e Katja Loos. "Enzymatic Polymerization of Furan-2,5-Dicarboxylic Acid-Based Furanic-Aliphatic Polyamides as Sustainable Alternatives to Polyphthalamides". Biomacromolecules 16, n.º 11 (12 de outubro de 2015): 3674–85. http://dx.doi.org/10.1021/acs.biomac.5b01172.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

33

Sommerauer, Grzybek, Elsaesser, Benisek, Sepperer, Dachs, Hüsing, Petutschnigg e Tondi. "Furfuryl Alcohol and Lactic Acid Blends: Homo- or Co-Polymerization?" Polymers 11, n.º 10 (20 de setembro de 2019): 1533. http://dx.doi.org/10.3390/polym11101533.

Texto completo da fonte

Resumo:

Furfuryl alcohol (FA) and lactic acid (LA) are two of the most interesting biomolecules, easily obtainable from sugars and hence extremely attractive for green chemistry solutions. These substances undergo homopolymerization and they have been rarely considered for copolymerization. Typically, FA homopolymerizes exothermically in an acid environment producing inhomogeneous porous materials, but recent studies have shown that this reaction can be controlled and therefore we have implemented this process to trigger the copolymerization with LA. The mechanical tests have shown that the blend containing small amount of FA were rigid and the fracture showed patterns more similar to the one of neat polyfurfuryl alcohol (PFA). This LA-rich blend exhibited higher chloroform and water resistances, while thermal analyses (TG and DSC) also indicated a higher furanic character than expected. These observations suggested an intimate interconnection between precursors which was highlighted by the presence of a small band in the ester region of the solid state 13C–NMR, even if the FT-IR did not evidence any new signal. These studies show that these bioplastics are basically constituted of PLA and PFA homopolymers with some small portion of covalent bonds between the two moieties.

Estilos ABNT, Harvard, Vancouver, APA, etc.

34

Vinod, Nivedha, e Saikat Dutta. "Production of Alkyl Levulinates from Carbohydrate-Derived Chemical Intermediates Using Phosphotungstic Acid Supported on Humin-Derived Activated Carbon (PTA/HAC) as a Recyclable Heterogeneous Acid Catalyst". Chemistry 5, n.º 2 (6 de abril de 2023): 800–812. http://dx.doi.org/10.3390/chemistry5020057.

Texto completo da fonte

Resumo:

This work reports a straightforward and high-yielding synthesis of alkyl levulinates (ALs), a class of promising biofuel, renewable solvent, and chemical feedstock of renewable origin. ALs were prepared by the acid-catalyzed esterification of levulinic acid (LA) and by the alcoholysis of carbohydrate-derived chemical platforms, such as furfuryl alcohol (FAL) and α-angelica lactone (α-AGL). Phosphotungstic acid (PTA) was chosen as the solid acid catalyst for the transformation, which was heterogenized on humin-derived activated carbon (HAC) for superior recyclability. Using HAC as catalyst support expands the scope of valorizing humin, a complex furanic resin produced inevitably as a side product (often considered waste) during the acid-catalyzed hydrolysis/dehydration of sugars and polymeric carbohydrates. Under optimized conditions (150 °C, 7 h, 25 wt.% of 20%PTA/HAC-600 catalyst), ethyl levulinate (EL) was obtained in an 85% isolated yield starting from FAL. Using the general synthetic protocol, EL was isolated in 88% and 84% yields from LA and α-AGL, respectively. The 20%PTA/HAC-600 catalyst was successfully recovered from the reaction mixture and recycled for five cycles. A marginal loss in the yield of ALs was observed in consecutive catalytic cycles due to partial leaching of PTA from the HAC support.

Estilos ABNT, Harvard, Vancouver, APA, etc.

35

Khrisanapant, Prit, Biniam Kebede, Sze Ying Leong e Indrawati Oey. "Effects of Hydrothermal Processing on Volatile and Fatty Acids Profile of Cowpeas (Vigna unguiculata), Chickpeas (Cicer arietinum) and Kidney Beans (Phaseolus vulgaris)". Molecules 27, n.º 23 (24 de novembro de 2022): 8204. http://dx.doi.org/10.3390/molecules27238204.

Texto completo da fonte

Resumo:

Legumes are an economical source of protein, starch, dietary fibre, fatty acids, vitamins and minerals. However, they are not as fully utilised, due to volatile compounds contributing to their undesirable odour. The purpose of this work was to understand the processing time’s effect on the legumes’ volatile profile. Hence, this study investigated the effects of hydrothermal processing times on the volatile and fatty acids profiles of cowpeas, chickpeas and kidney beans. All legumes were pre-soaked (16 h) and then hydrothermally processed at 95 °C for 15 to 120 min, using an open system to approximate standard household cooking practices and a closed system to represent industrial processing. Alcohol, aldehyde, acid and ester volatile compounds showed decreasing trends during processing, which can be associated with enzyme inactivation and process-induced degradation. This work showed that processing at 95 °C for 30 min significantly reduced the number of compounds commonly associated with undesirable odour, but showed no significant change in the fatty acid profile. Other volatiles, such as furanic compounds, pyrans and sulphur compounds, showed an increasing trend during processing, which can be related to the Maillard reactions. This observation contributes to the growing knowledge of legume processing and its impact on volatile flavour. It can advise consumers and the industry on selecting processing intensity to maximise legume utilisation.

Estilos ABNT, Harvard, Vancouver, APA, etc.

36

Rodríguez-Félix, Elizabeth, Silvia Contreras-Ramos, Gustavo Davila-Vazquez, Jacobo Rodríguez-Campos e Erika Marino-Marmolejo. "Identification and Quantification of Volatile Compounds Found in Vinasses from Two Different Processes of Tequila Production". Energies 11, n.º 3 (26 de fevereiro de 2018): 490. http://dx.doi.org/10.3390/en11030490.

Texto completo da fonte

Resumo:

Vinasses are the main byproducts of ethanol distillation and distilled beverages worldwide and are generated in substantial volumes. Tequila vinasses (TVs) could be used as a feedstock for biohydrogen production through a dark fermentative (DF) process due to their high content of organic matter. However, TV components have not been previously assayed in order to evaluate if they may dark ferment. This work aimed to identify and quantify volatile compounds (VC) in TV and determine if the VC profile depends upon the type of production process (whether the stems were initially cooked or not). TVs were sampled from 3 agave stems with a not-cooking (NC) process, and 3 agave stems with a cooking (C) process, and volatile compounds were determined by gas chromatography coupled with mass spectrometry (GC–MS). A total of 111 volatile compounds were identified, the TV from the cooking process (C) showed the higher presence of furanic compounds (furfural and 5-(hydroxymethyl) furfural) and organic acids (acetic acid and butyric acid), which have been reported as potential inhibitors for DF. To our knowledge, this is the first description of the VC composition from TVs. This study could serve as a base for further investigations related to vinasses from diverse sources.

Estilos ABNT, Harvard, Vancouver, APA, etc.

37

Antonetti, Claudia, Anna Maria Raspolli Galletti, Domenico Licursi, Sara Fulignati, Nicola Di Fidio, Federica Zanetti, Andrea Monti, Tommaso Tabanelli e Fabrizio Cavani. "Niobium and Zirconium Phosphates as Green and Water-Tolerant Catalysts for the Acid-Catalyzed Valorization of Bio-Based Chemicals and Real Lignocellulosic Biomasses". Catalysts 12, n.º 10 (7 de outubro de 2022): 1189. http://dx.doi.org/10.3390/catal12101189.

Texto completo da fonte

Resumo:

Commercial niobium and synthesized zirconium phosphates were tested as water-tolerant heterogeneous acid catalysts in the hydrothermal conversion of different bio-based substrates. Different acid-catalyzed reactions were performed using biomass-derived model compounds and more complex real lignocellulosic biomasses as the substrate. The conversion of glucose and cellulose was preliminarily investigated. Then, a wide plethora of raw lignocellulosic biomasses, such as conifer wood sawdust, Jerusalem artichoke, sorghum, miscanthus, foxtail millet, hemp and Arundo donax, were valorized towards the production of water-soluble saccharides, 5-hydroxymethylfurfural (HMF), levulinic acid (LA) and furfural. The different catalytic performances of the two phosphates were explained on the basis of their acid features, total acidity, Brønsted/Lewis acid sites ratio and strength. Moreover, a better insight into their structure–acidity relationship was proposed. The different acid properties of niobium and zirconium phosphates enabled us to tune the reaction towards target products, achieving from glucose maximum HMF and LA yields of 24.4 and 24.0 mol%, respectively. Remarkably, when real Jerusalem artichoke biomass was adopted in the presence of niobium and zirconium phosphate, maximum yields of furanic compounds and cellulose-derived sugars of 12.7 and 50.0 mol%, respectively, were obtained, after only 1 h of reaction. The synthesized hydrolysates, which were found to be rich in C5 and C6 carbohydrates, can be better exploited for the cascade production of more added-value bio-products.

Estilos ABNT, Harvard, Vancouver, APA, etc.

38

Lima, Sergio, Margarida M. Antunes, Martyn Pillinger e Anabela A. Valente. "ChemInform Abstract: Ionic Liquids as Tools for the Acid-Catalyzed Hydrolysis/Dehydration of Saccharides to Furanic Aldehydes". ChemInform 43, n.º 12 (23 de fevereiro de 2012): no. http://dx.doi.org/10.1002/chin.201212223.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

39

Chen, Xinyi, Nathanael Guigo, Antonio Pizzi, Nicolas Sbirrazzuoli, Bin Li, Emmanuel Fredon e Christine Gerardin. "Ambient Temperature Self-Blowing Tannin-Humins Biofoams". Polymers 12, n.º 11 (17 de novembro de 2020): 2732. http://dx.doi.org/10.3390/polym12112732.

Texto completo da fonte

Resumo:

Ambient temperature self-blowing tannin–furanic foams have been prepared by substituting a great part—even a majority—of furfuryl alcohol with humins, a polyfuranic material derived from the acid treatment at high temperature of fructose. Closed-cell foams were prepared at room temperature and curing, while interconnected-cell foams were prepared at 80 °C and curing, this being due to the more vigorous evaporation of the solvent. These foams appear to present similar characteristics as other tannin–furanic foams based only on furfuryl alcohol. A series of tannin–humins–furfuryl alcohol oligomer structures have been defined indicating that all three reagents co-react. Humins appeared to react well with condensed tannins, even higher molecular weight humins species, and even at ambient temperature, but they react slower than furfuryl alcohol. This is due to their high average molecular weight and high viscosity, causing their reaction with other species to be diffusion controlled. Thus, small increases in solvent led to foams with less cracks and open structures. It showed that furfuryl alcohol appears to also have a role as a humins solvent, and not just as a co-reagent and self-polymerization heat generator for foam expansion and hardening. Stress-strain for the different foams showed a higher compressive strength for both the foam with the lowest and the highest proportion of humins, thus in the dominant proportions of either furfuryl alcohol or the humins. Thus, due to their slower reactivity as their proportion increases to a certain critical level, more of them do proportionally participate within the expansion/curing time of the foam to the reaction.

Estilos ABNT, Harvard, Vancouver, APA, etc.

40

Anjos, Ofélia, Carlos A. L. Antunes, Sheila Oliveira-Alves, Sara Canas e Ilda Caldeira. "Characterisation of Low Molecular Weight Compounds of Strawberry Tree (Arbutus unedo L.) Fruit Spirit Aged with Oak Wood". Fermentation 10, n.º 5 (13 de maio de 2024): 253. http://dx.doi.org/10.3390/fermentation10050253.

Texto completo da fonte

Resumo:

There is a trend towards the commercialisation of strawberry tree fruit spirit (AUS) with wood ageing, motivated by its favourable sensory characteristics. Additionally, further studies are necessary to elucidate the optimal conditions regarding ageing time and toasting level. This study evaluated the changes in colour and low molecular weight compounds (LMWC) of AUS aged for three and six months using oak wood (Quercus robur L.) with light, medium and medium plus toasting levels. For this purpose, phenolic acids (gallic, ellagic, ferulic and syringic acids), phenolic aldehydes (vanillin, syringaldehyde, coniferaldehyde and sinapaldehyde) and furanic aldehydes (furfural, 5-hydroxymethylfurfural and 5-methylfurfural) were quantified using the HPLC method. Chromatic characteristics, colour sensory analysis and total polyphenol index were also analysed. Fourier transform near-infrared spectroscopy (FT-NIR) was used to discriminate between samples. The results emphasized the favourable effect of oak wood contact on enhancing the colour and enriching AUS with low molecular weight compounds (LMWC). AUS aged in medium toasted wood exhibits high levels of total phenolic index, 5-hydroxymethylfurfural, furfural, coniferaldehyde, sinapaldehyde, sum LMWC and chromatic characteristics b* and C. Concentrations of syringaldehyde, ellagic acid, vanillin and syringic acid and a lighter colour (a* chromaticity coordinates) are higher in AUS aged with slightly more toasted wood. Nearly all analysed parameters showed an increase with ageing time. The FT-NIR technique allowed for the differentiation of aged AUS, focusing more on ageing time than on toasting level.

Estilos ABNT, Harvard, Vancouver, APA, etc.

41

Kovaleva, Аlla, Raal Ain, Ilina Tetiana, Alina Osmachko, Olga Goryacha, Ludmila Omelyanchik e Oleh Koshovyi. "Carboxylic acids in the flowers of Veronica spicata L. and Veronica incana L." ScienceRise: Pharmaceutical Science, n.º 1(35) (28 de fevereiro de 2022): 37–43. http://dx.doi.org/10.15587/2519-4852.2022.253541.

Texto completo da fonte

Resumo:

In the Ukrainian flora, species of Veronica L. genus (Plantaginaceae Juss.) are classified into 8 sections. Among the representatives of Pseudolysimachion W. D. J. Koch section in the Kharkiv region, Veronica spicata L. (spike speedwell) and Veronica incana L. (Veronica spicata L. subsp. incana (L.) Walters, silver speedwell) are common. Plants are used for the treatment of upper respiratory tract diseases, malignant neoplasms, gastrointestinal tract and genitourinary system disorders, diabetes mellitus. The aim of the research was to study the carboxylic acids of flowers of Veronica spicata L. and Veronica incana L. Materials and methods. The objects of the research were flowers of Veronica spicata L. and Veronica incana L., collected in the flowering stage in the Botanical Garden of Karazin University (Kharkiv, Ukraine) in summer 2018. The study of carboxylic acid composition was performed by chromatography-mass spectrometry on a 6890N MSD/DS Agilent Technologies chromatograph with a 5973N mass spectrometric detector. Identification of methyl esters of acids was performed using data from the mass spectrum libraries NIST 05 and Willey 2007 in a combination with programs for the identification of AMDIS and NIST; also, their retention time and the retention times of standard compounds were compared. Results. In Veronica incana L. flowers, 37 carboxylic acids were identified and quantified, constituting 1.05 %. In Veronica spicata L. flowers, 32 carboxylic acids were identified and quantified, the total content of which was 2.75 %. Conclusions. A higher carboxylic acid content was established in the flowers of Veronica spicata L. The fatty acid composition of Veronica incana L. flowers is characterized by a comparable content of saturated and unsaturated acids, while in Veronica spicata L. flowers, unsaturated fatty acids prevail over saturated fatty acids. The content of aromatic acids in the flowers of studied species was comparable. The characteristic carboxylic acids in the flowers of Veronica incana L. are oxalic, 3-hydroxy-2-methylglutaric, pentadecanoic, heneicosanoic, tricosanic,4-hydroxybenzoic, 4-methoxybenzoic and 3,4-dimethoxybenzoic acids; in the flowers of Veronica spicata L. – 2-hydroxy-3-methylglutaric, α-furanic and homovanillic acids

Estilos ABNT, Harvard, Vancouver, APA, etc.

42

Li, Hui, e Zheng Fang. "Resourceful Treatment of Dioscorea zingiberensis Wastewater Using a Double-Chamber Microbial Fuel Cell". Advanced Materials Research 602-604 (dezembro de 2012): 1081–85. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.1081.

Texto completo da fonte

Resumo:

A double-chamber microbial fuel cell (MFC) was used to dispose Dioscorea Zingiberensis wastewater and retrieve electrical energy. Both electrical performance and contaminant degradation characteristics were investigated. The potential of the MFC achieved 0.50-0.55 V over a 1000 ohm resistance, and the Coulombic efficiency was 7.01% or so. The maximum power density was about 350 mW/m2. During the operation cycle, COD was removed 82.6% and 10.9% in the anodic and cathodic chamber, respectively. In anodic chamber, simple acid, sugars and cellulose in wastewater were utilized while complicated organic matters including furanic and aromatic compounds were broken down by breaking side-chains and opening rings. In cathodic chamber, fatty ester and alkene were removed while aromatic compounds were degraded further. The results indicate that MFC provides a new approach for resource recovery treatment of Dioscorea Zingiberensis wastewater.

Estilos ABNT, Harvard, Vancouver, APA, etc.

43

Lima, Sérgio, Margarida M. Antunes, Auguste Fernandes, Martyn Pillinger, Maria Filipa Ribeiro e Anabela A. Valente. "Acid-Catalysed Conversion of Saccharides into Furanic Aldehydes in the Presence of Three-Dimensional Mesoporous Al-TUD-1". Molecules 15, n.º 6 (28 de maio de 2010): 3863–77. http://dx.doi.org/10.3390/molecules15063863.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

44

Antunes, Margarida M., Sérgio Lima, Auguste Fernandes, Ana L. Magalhães, Patrícia Neves, Carlos M. Silva, Maria F. Ribeiro et al. "MFI Acid Catalysts with Different Crystal Sizes and Porosity for the Conversion of Furanic Compounds in Alcohol Media". ChemCatChem 9, n.º 14 (6 de fevereiro de 2017): 2747–59. http://dx.doi.org/10.1002/cctc.201601236.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

45

Matos, Marina, Andreia F. Sousa, Ana C. Fonseca, Carmen S. R. Freire, Jorge F. J. Coelho e Armando J. D. Silvestre. "A New Generation of Furanic Copolyesters with Enhanced Degradability: Poly(ethylene 2,5-furandicarboxylate)-co-poly(lactic acid) Copolyesters". Macromolecular Chemistry and Physics 215, n.º 22 (25 de junho de 2014): 2175–84. http://dx.doi.org/10.1002/macp.201400175.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

46

Gebresillase, Mahlet N., Raghavendra Shavi e Jeong Gil Seo. "A comprehensive investigation of the condensation of furanic platform molecules to C14–C15 fuel precursors over sulfonic acid functionalized silica supports". Green Chemistry 20, n.º 22 (2018): 5133–46. http://dx.doi.org/10.1039/c8gc01953c.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

47

Gonzalez, Mabel, Adriana Celis, Marcela Guevara-Suarez, Jorge Molina e Chiara Carazzone. "Yeast Smell Like What They Eat: Analysis of Volatile Organic Compounds of Malassezia furfur in Growth Media Supplemented with Different Lipids". Molecules 24, n.º 3 (24 de janeiro de 2019): 419. http://dx.doi.org/10.3390/molecules24030419.

Texto completo da fonte

Resumo:

Malassezia furfur is part of the human skin microbiota. Its volatile organic compounds (VOCs) possibly contribute to the characteristic odour in humans, as well as to microbiota interaction. The aim of this study was to investigate how the lipid composition of the liquid medium influences the production of VOCs. Growth was performed in four media: (1) mDixon, (2) oleic acid (OA), (3) oleic acid + palmitic acid (OA+PA), and (4) palmitic acid (PA). The profiles of the VOCs were characterized by HS-SPME/GC-MS in the exponential and stationary phases. A total number of 61 VOCs was found in M. furfur, among which alkanes, alcohols, ketones, and furanic compounds were the most abundant. Some compounds previously reported for Malassezia (γ-dodecalactone, 3-methylbutan-1-ol, and hexan-1-ol) were also found. Through our experiments, using univariate and multivariate unsupervised (Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA)) and supervised (Projection to Latent Structures Discriminant Analysis (PLS-DA)) statistical techniques, we have proven that each tested growth medium stimulates the production of a different volatiles profile in M. furfur. Carbon dioxide, hexan-1-ol, pentyl acetate, isomer5 of methyldecane, dimethyl sulphide, undec-5-ene, isomer2 of methylundecane, isomer1 of methyldecane, and 2-methyltetrahydrofuran were established as differentiating compounds among treatments by all the techniques. The significance of our findings deserves future research to investigate if certain volatile profiles could be related to the beneficial or pathogenic role of this yeast.

Estilos ABNT, Harvard, Vancouver, APA, etc.

48

Li, Xuehui, Bowen Liu, Lulu Zheng, Hisham Essawy, Zhiyan Liu, Can Liu, Xiaojian Zhou e Jun Zhang. "Facile Synthesis of Formaldehyde-Free Bio-Based Thermoset Resins for Fabrication of Highly Efficient Foams". Polymers 14, n.º 23 (25 de novembro de 2022): 5140. http://dx.doi.org/10.3390/polym14235140.

Texto completo da fonte

Resumo:

Bio-based biodegradable foams were formulated from a crosslinkable network structure combining starch, furfuryl alcohol, glyoxal, and condensed tannin in the presence of p-toluenesulfonic acid (pTSA) and azodicarbonamide (AC) as a foaming agent. More importantly, the reinforcement of gelatinized starch–furanic foam using tannin, originating from forestry, resulted in an excellent compressive strength and lower pulverization ratio. Moreover, the addition of tannin guaranteed a low thermal conductivity and moderate flame retardancy. Fourier transform infrared (FTIR) spectroscopy approved the successful polycondensation of these condensing agents under the employed acidic conditions. Moreover, the catalytic effect of pTSA on the foaming agent induced liberation of gases, which are necessary for foam formation during crosslinking. Scanning electron microscopy (SEM) showed foam formation comprising closed cells with uniform cell distribution and appropriate apparent density. Meanwhile, the novel foam exhibited biodegradation under the action of Penicillium sp., as identified by the damage of cell walls of this foam over a period of 30 days.

Estilos ABNT, Harvard, Vancouver, APA, etc.

49

Gu, Canshuo, Lungang Chen, Yong Liu, Xinghua Zhang, Jianguo Liu, Qi Zhang, Chenguang Wang e Longlong Ma. "One-pot conversion of biomass-derived levulinic acid to furanic biofuel 2-methyltetrahydrofuran over bimetallic NiCo/γ-Al2O3 catalysts". Molecular Catalysis 524 (maio de 2022): 112317. http://dx.doi.org/10.1016/j.mcat.2022.112317.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

50

Rojas-Buzo, Sergio, Pilar García-García e Avelino Corma. "Hf-based metal–organic frameworks as acid–base catalysts for the transformation of biomass-derived furanic compounds into chemicals". Green Chemistry 20, n.º 13 (2018): 3081–91. http://dx.doi.org/10.1039/c8gc00806j.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

Artigos de revistas sobre o tema "Furanic acid"

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos