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Littérature scientifique sur le sujet « Lignin Polymeric Fraction »
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Articles de revues sur le sujet "Lignin Polymeric Fraction"
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Johansson, C. Ingemar, John N. Saddler et Rodger P. Beatson. « Characterization of the Polyphenolics Related to the Colour of Western Red Cedar (Thuja plicata Donn) Heartwood ». Holzforschung 54, no 3 (13 avril 2000) : 246–54. http://dx.doi.org/10.1515/hf.2000.042.
Texte intégralRésumé :
Summary Three quarters of the western red cedar's heartwood colour is due to a polymeric material easily isolated by methanol extraction. The nature of this polymer has not been fully investigated and published information is contradictory. Our initial examination of the coloured polymer by pyrolysis-gas chromatography, combined with mass spectrometry, indicated that the polymer was guaiacyl in nature and thus similar to softwood lignin. However, analysis by infrared spectroscopy indicated the presence of both lignin and lignan like moieties. To clarify this issue a more detailed analysis was conducted using nuclear magnetic resonance spectroscopy (1H NMR, 31P NMR, 13C NMR). Analysis of the spectra and comparison with the spectra of plicatic acid and a product from mild acid treatment of plicatic acid, indicated that the polymeric fraction was derived almost entirely from lignans. During polymer formation, the highly reactive pyrocatechol moiety in the plicatic acid is destroyed, leaving a guaiacyl-like polymer. The reaction mechanism appears to proceed via an ortho-quinone intermediate followed by polymerization.
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Lagerquist, Lucas, Andrey Pranovich, Ivan Sumerskii, Sebastian von Schoultz, Lari Vähäsalo, Stefan Willför et Patrik Eklund. « Structural and Thermal Analysis of Softwood Lignins from a Pressurized Hot Water Extraction Biorefinery Process and Modified Derivatives ». Molecules 24, no 2 (18 janvier 2019) : 335. http://dx.doi.org/10.3390/molecules24020335.
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In this work we have analyzed the pine and spruce softwood lignin fraction recovered from a novel pressurized hot water extraction pilot process. The lignin structure was characterized using multiple NMR techniques and the thermal properties were analyzed using thermal gravimetric analysis. Acetylated and selectively methylated derivatives were prepared, and their structure and properties were analyzed and compared to the unmodified lignin. The lignin had relatively high molar weight and low PDI values and even less polydisperse fractions could be obtained by fractionation based on solubility in i-PrOH. Condensation, especially at the 5-position, was detected in this sulphur-free technical lignin, which had been enriched with carbon compared to the milled wood lignin (MWL) sample of the same wood chips. An increase in phenolic and carboxylic groups was also detected, which makes the lignin accessible to chemical modification. The lignin was determined to be thermally stable up to (273–302 °C) based on its Tdst 95% value. Due to the thermal stability, low polydispersity, and possibility to tailor its chemical properties by modification of its hydroxyl groups, possible application areas for the lignin could be in polymeric blends, composites or in resins.
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Ventura, Maria, Marcelo E. Domine et Marvin Chávez-Sifontes. « Catalytic Processes For Lignin Valorization into Fuels and Chemicals (Aromatics) ». Current Catalysis 8, no 1 (21 juin 2019) : 20–40. http://dx.doi.org/10.2174/2211544708666190124112830.
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Valorization of lignocellulosic biomass becomes a sustainable alternative against the constant depletion and environmental problems of fossil sources necessary for the production of chemicals and fuels. In this context, a wide range of renewable raw materials can be obtained from lignocellulosic biomass in both polymeric (i.e. cellulose, starch, lignin) and monomeric (i.e. sugars, polyols, phenols) forms. Lignin and its derivatives are interesting platform chemicals for industry, although mainly due to its refractory characteristics its use has been less considered compared to other biomass fractions. To take advantage of the potentialities of lignin, it is necessary to isolate it from the cellulose/ hemicellulosic fraction, and then apply depolymerization processes; the overcoming of technical limitations being a current issue of growing interest for many research groups. In this review, significant data related to the structural characteristics of different types of commercial lignins are presented, also including extraction and isolation processes from biomass, and industrial feedstocks obtained as residues from paper industry under different treatments. The review mainly focuses on the different depolymerization processes (hydrolysis, hydrogenolysis, hydrodeoxygenation, pyrolysis) up to now developed and investigated analyzing the different hydrocarbons and aromatic derivatives obtained in each case, as well as the interesting reactions some of them may undergo. Special emphasis is done on the development of new catalysts and catalytic processes for the efficient production of fuels and chemicals from lignin. The possibilities of applications for lignin and its derivatives in new industrial processes and their integration into the biorefinery of the future are also assessed.
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Battestini Vives, Mariona, Johan Thuvander, Anders Arkell et Frank Lipnizki. « Low-Molecular-Weight Lignin Recovery with Nanofiltration in the Kraft Pulping Process ». Membranes 12, no 3 (9 mars 2022) : 310. http://dx.doi.org/10.3390/membranes12030310.
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Kraft lignin is an underutilized resource from the pulp and paper industry with the potential of being a key raw material for renewable fuels and chemicals. The separation of high-molecular-weight lignin from black liquor by ultrafiltration has been widely investigated, while the permeate containing low-molecular-weight lignin has received little attention. Nanofiltration can concentrate the low-molecular-weight lignin. This work, therefore, evaluates nanofiltration for the separation and concentration of low-molecular-weight lignin from the ultrafiltration permeate. For this study, eight flat polymeric sheet membranes and one polymeric hollow fiber membrane, with molecular weight cut-offs ranging from 100 to 2000 Da, were tested. A parametric study was conducted at 50 °C, 2.5–35 bar, and crossflow velocity of 0.3–0.5 m/s. At a transmembrane pressure of 35 bar, the best performing membranes were NF090801, with 90% lignin retention and 37 L/m2·h, and SelRO MPF-36, with 84% lignin retention and 72 L/m2·h. The other membranes showed either very high lignin retention with a very low flux or a high flux with retention lower than 80%. Concentration studies were performed with the two selected membranes at conditions (A) 50 °C and 35 bar and (B) 70 °C and 15 bar. The NF090801 membrane had the highest flux and lignin retention during the concentration studies. Overall, it was shown that the nanofiltration process is able to produce a concentrated lignin fraction, which can be either used to produce valuable chemicals or used to make lignin oil.
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Krutov, Stepan M., Dmitry V. Evtuguin, Elena V. Ipatova, Sonia A. O. Santos et Yurii N. Sazanov. « Modification of acid hydrolysis lignin for value-added applications by micronization followed by hydrothermal alkaline treatment ». Holzforschung 69, no 6 (1 août 2015) : 761–68. http://dx.doi.org/10.1515/hf-2014-0264.
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Abstract Technical hydrolysis lignin (THL) was micronized by grinding in a rotary-jet mill to obtain a fraction of approximately 5 mm. Both initial and milled THLs were liquefied by thermal alkaline treatment at 220°C for 2 h. Upgraded THLs that were nonmilled (L1) and milled (L2) were desalted by treatment with cation-exchanged resin and were dried. Micronization affected the course of hydrothermal alkaline treatment and the structure and composition of the obtained lignin. Thus, L2 contained much less concomitant polysaccharides and extractives than L1 and was more condensed. The molecular weights of L1 and L2 were 1100 and 1000 Da, respectively, as determined by size-exclusion chromatography. Structural characterization carried out by employing tandem electrospray ionization-mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy revealed that small amounts of β-O-4 (∼6 mol.%), β-5, and β-β structures still remained in L1 and L2. Overall, upgraded lignins are oligomers (trimers-pentamers) with highly degraded propane chains and possess polyconjugated condensed aromatic structures. Upgraded THL seems to be a promising raw material for polymeric formulations.
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Lee, Jae Hoon, Shin Young Park, In-Gyu Choi et Joon Weon Choi. « Investigation of Molecular Size Effect on the Formation of Lignin Nanoparticles by Nanoprecipitation ». Applied Sciences 10, no 14 (17 juillet 2020) : 4910. http://dx.doi.org/10.3390/app10144910.
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In recent years, several studies focused on the synthesis of lignin-based nanoparticle in aqueous solution and its potential applications of the drug carrier were investigated. In this study, soda lignin (SL) nanoparticles (i.d. 128–560 nm) were synthesized by the nanoprecipitation process at three different concentrations (1, 2, and 4 mg/mL THF) with various molecular sizes of soda lignin (NP-F1, NP-F2, and NP-F3) obtained from sequential solvent extraction. The average molecular weights of SL, F1, F2, F3, F4, and F5 were 3130, 1190, 2550, 3680, 5310, and 14,650, respectively. The average size of the spherical lignin nanoparticle was a minimum of 128 nm for NP-C1 and the size increased up to 560 nm with increasing concentration. Particle surface charge increased with increasing concentration from −26 mV for NP-C1 to −38 mV for NP-C4. Contrary to expected general trends in polymeric nanoparticles, there was no remarkable change or trend with increasing lignin molecular weight since chemical structures of each lignin fraction are also remarkably different. Further studies to learn correlation between properties of lignin nanoparticle and its additional details regarding the chemical structures is needed.
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García-Vargas, Minerva C., María del Mar Contreras, Irene Gómez-Cruz, Juan Miguel Romero-García et Eulogio Castro. « Avocado-Derived Biomass : Chemical Composition and Antioxidant Potential ». Proceedings 70, no 1 (10 novembre 2020) : 100. http://dx.doi.org/10.3390/foods_2020-07750.
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Avocado has become fashionable due to its great organoleptic and nutritional properties. It is consumed as a fresh product and it is also processed to obtain salad oil and guacamole. In all cases, the only usable portion is the pulp. Therefore, to be a more sustainable and profitable agribusiness, it is important to recognize which compounds from the peel and the stone waste can be converted into valuable bio-products. Therefore, their chemical composition was determined according to the National Renewable Energy Laboratory, the total phenolic content by the Folin-Ciocalteu method and the antioxidant properties by the FRAP and TEAC assays. The main components of the peel and stone were acid-insoluble lignin (35.0% and 15.3%, respectively), polymeric sugars (23.6% and 43.9%, respectively), and the aqueous extractives (15.5% and 16.9%, respectively). Both biomasses contain lipids and protein, but a minor proportion (<6%). The valorization of lignin and sugars is of interest given the high content; stones are a rich source of glucose (93.2% of the polymeric fraction), which could be used to obtain biofuels or derivatives of interest. The extractive fraction of the peel contained the highest number of phenolic compounds (4.7 g/100 g biomass), mainly concentrated in the aqueous fraction (i.e., 87%) compared to the ethanol one, which was subsequently extracted. It correlated with major antioxidant activity and, therefore, the peel can be applied to obtain antioxidants and water can be used as an environmentally friendly extraction solvent.
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Fedoros, Elena, Sergey Pigarev, Natalya Ivanenko, Megan Westbury et Nikolay Solovyev. « Protein Binding of a Novel Platinum-Based Anticancer Agent BP-C1 Containing a Lignin-Derived Polymeric Ligand ». Applied Sciences 11, no 22 (20 novembre 2021) : 11008. http://dx.doi.org/10.3390/app112211008.
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Platinum (Pt) antineoplastic agents remain indispensable for the treatment of oncological disease. Pt-based drugs are mainly used in the therapy of ovarian cancer and non-small-cell lung carcinoma. A novel platinum-containing antineoplastic agent BP-C1 is a complex of diamminoplatinum with an oxygen-donor polymeric ligand of benzene-polycarboxylic acids, isolated from natural lignin. The aim of the study was to investigate ex vivo protein binding of BP-C1. Protein binding of BP-C1 was tested using equilibrium dialysis. Pooled blood plasma was used in the study. Control solutions contained the same dosages of BP-C1 in PBS (pH 7.2). Plasma and control solutions were submitted to equilibrium dialysis across a vertical 8 kDa cut-off membrane for 4 h at 37 °C under gentle shaking. Platinum was quantified in dialysis and retained fractions using inductively coupled plasma mass spectrometry after microwave digestion. The dialysis system was tested and validated; this showed no protein saturation with platinum. A medium degree of binding of platinum to macromolecular species of ca. 60% was observed. The study showed the maintenance of a high fraction of free BP-C1 in the bloodstream, facilitating its pharmacological activity.
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Hernandez-Pérez, G., G. Goma et J. L. Rols. « Enhanced degradation of lignosulfonated compounds by Streptomyces viridosporus ». Water Science and Technology 38, no 4-5 (1 août 1998) : 289–97. http://dx.doi.org/10.2166/wst.1998.0647.
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Degradation of lignosulfonated compounds by S. viridosporus strain T7A on nutritive or mineral culture media was quantified. Two lignosulfonated compounds, differing in their molecular mass distributions and chemical structures, were used: lignosulfonate (1–80 kDa) and vanisperse, a sulfonated oxylignin (1–20 kDa). The use of nutritive culture medium (containing Biosoyase) enhanced both the growth of S. viridosporus and production of lignin peroxidase (LiP) leading to enhanced lignocellulose degradation, but no lignosulfonated compound degradation was observed. A fraction of these compounds underwent a molecular transformation, producing non-biodegradable acid precipitable polymeric lignin (APPL). When a mineral culture medium (containing glycerol as additional organic carbon source) was used, approximately 21 and 35% of lignosulfonate and vanisperse were respectively degraded, with little APPL production. LiP activity was growth-associated and significant modifications of molecular mass distributions of both lignosulfonated compounds were observed. A mixed natural microbial population, collected in an aerated lagoon treating Fluff pulp effluent, was used to evaluate the biodegradability of lignosulfonate products from S. viridosporus cultures. This population was (i) unable to degrade lignosulfonate products, and (ii) decreased the lignosulfonate degradation capacity of S. viridosporus. Antagonistic effects of the mixed population on S. viridosporus were observed. In the light of this, bioaugmentation strategies involving addition of S. viridosporus are unlikely to be successful and alternative degradation strategies need to be developed.
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Leite, Rogério, Yêda Medeiros B. de Almeida, Sandra Maria Sarmento, Kleber G. B. Alves, Etelino Feijó de Melo et Rosa Maria Souto-Maior. « Solvent-fractionated sugar cane bagasse lignin : structural characteristics and electro-spinnability ». e-Polymers 16, no 2 (1 mars 2016) : 137–44. http://dx.doi.org/10.1515/epoly-2015-0229.
Texte intégralRésumé :
AbstractLignin is one of the most abundant macromolecules on Earth. Lignins are obtained as by-products from the paper industry and used mostly as fuel. Their diverse composition has limited the development of high added-value applications: however, because of their abundance and sustainable origin, there is a growing interest in using lignins as a raw material and as a replacement for oil derivatives. In order to use lignins in bio-refineries, several processes must be studied and standardized. Lignin fractionation using solvents is a promising process. In this study, lignin from sugar cane bagasse (L1) was fractionated with solvents, and the fractions were characterized to evaluate structural aspects relevant for the production of fibers. L1 was extracted into four fractions with toluene (E1), ethanol (E2), methanol (E3), and dimethyl sulfoxide (DMSO, E4). Fractions E2, E3, and E4, showed only slightly different molar masses and molar mass distribution, but have relevant differences in their structural characteristics and processability. The ethanol extract (E2) provided lignins with a more flexible structure, and electro-spinning resulted in the production of nanofibers with diameters between 60 and 120 nm; the methanol fraction (E3) produced nanospheres with diameters between 90 and 350 nm; the DMSO fraction (E4) covered only a surface with electro-spray. These results show the possibility of developing high added-value applications using fractions of lignin from distinct biomasses or from their combination.
Thèses sur le sujet "Lignin Polymeric Fraction"
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LAZZATI, ZELDA. « Speciation of particulate matter's organic fraction and its mechanis of action on human health ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/7466.
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Three main researches have been employed for the implementation of a protocol analysis for the characterization and quantification of the lignin fraction in the particulate matter at the concentration matrix level; the implementation of different methods of analysis of the toxic interesting pollutants, Oxy-PAHs; Nitro-PAHs and the Bisphenol A, that together with the large set of performed analysis, allowed the characterization of some PM fractions in relation with Indoor and Outdoor concentrations, human exposure and Urban – Rural – Remote sites composition. At last an in silica method was developed for the research of the proteins involved in the interaction with the pollutants of interest, optimized on Bisphenol A because of its history and recent interaction study with the Nuclear Receptors. From the involved pathway the Blood Serine Proteases are used to test the accuracy and reproducibility of obtained Autodock4.0 and Dock4.0 data. The method results useful for research on the biological mechanism of action in relation with both matrix concentrations and in vivo and in vitro studies. The data predicted will be confirmed by NMR analysis. The newest docking program gives more and more reproducible data, accurate and empirically shaped on the domain problem, at last the experimental data had to confirm or not confirm the predictions.