Jiebing Li

KTH Royal Institute of Technology, Tukholma, Stockholm, Sweden

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Publications (45)108.85 Total impact

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    ABSTRACT: Cellulose nanocrystals (CNs) were prepared from tunicate by enzymatic hydrolysis (ECN), TEMPO-mediated oxidation (TCN) and acid hydrolysis (ACN). They were cast alone or blended with glucomannan (GM) from konjac or spruce to prepare films. Different CNs were obtained with a yield of ECN > TCN > ACN with corresponding order of decreased Mw but increased crystallinity. The CNs’ diameters were on the nanometre scale, with lengths of ECN > TCN > ACN. For CN-films, TCN and ACN fibrils were stretched and parallel to each other due to surface charges. For CN–GM films, both components interacted strongly with each other, resulting in changes of crystallinity, specific surface area, fibril diameter and contact angle compared with CN films. The composite films had good thermal, optical and mechanical properties; the last ones are apparently better than similar films reported in the literature. This is the first systematic study of different tunicate CN–GM nanocomposite films and the first ever for spruce GM.
    Carbohydrate Polymers 03/2015; 117:286–296. DOI:10.1016/j.carbpol.2014.09.020 · 4.07 Impact Factor
  • Yadong Zhao, Jiebing Li
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    ABSTRACT: The high crystallinity and the high microfibrils aspect ratio of tunicate cellulose (TC) indicate TC’s excellent chemical and material applications. However, its quantity and quality from different species have never been systematically reported and compared. In this study, the tunics of Ciona intestinalis (CI), Ascidia sp. (AS), Halocynthia roretzi (HR) and Styela plicata (SP) were processed to TC after an identical prehydrolysis-kraft cooking-bleaching sequence, while the tunicate fibrils were chemically and structurally characterized in situ and during the sequence. All tunics studied were composed of crystalline cellulose embedded with protein, lipids, sulfated glycans and mucopolysaccharides. The native composite structures are all very compact. However, the tunics from Phlebobranchia order (CI and AS) are soft, while those from Stolidobranchia, HR and SP, are hard. Fibrous cellulose could be prepared after removing the lipids, sulfated glycans and mucopolysaccharides through prehydrolysis, protein removal through kraft cooking and a final purification by bleaching. The final product is ~100 % pure cellulose which is in large molecular masses, composed of highly crystalline Iβ crystals, in elementary microfibrils form, with high specific surface area and thermal stability. There were lower TC yields from the soft tunics than from the hard ones. The cellulose fibrils had a section shape of lozenges with higher crystallinity. This study demonstrates that TC could be obtained in different yields and exhibited different chemical and morphological structures depending on the species. There is a great potential of tunicate resources for preparing excellent chemical and material cellulose.
    Cellulose 10/2014; 21(5). DOI:10.1007/s10570-014-0348-6 · 3.03 Impact Factor
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    ABSTRACT: The main hemicellulose in softwood, glucomannan (GM), structurally resembles cellulose but has quite different physical and chemical properties. In addition to branching and original acetylation, the only other difference between these two β-1,4-linked glycans is the configuration at C-2 in approximately 80% of the sugar residues. In contrast to glucose, the 2-OH in mannose has an axial orientation. The influence of this stereochemistry on the relative reactivities of glucosyl compared to mannosyl units in methylation reactions are studied in this work. Glucomannan isolated from spruce (SGM) and commercially available konjac glucomannan (KGM) was methylated in DMSO/Li-dimsyl/MeI and water/NaOH/MeI system, respectively. In the early stage of the reaction, the glucose part of the SGM achieved slightly higher DS values than the mannose residues, but the overall relative rate constants were close to 1:1. The order of reactivities in glucose was k2>k3>k6 and k3>k2>k6 for mannose (in DMSO/Li-dimsyl/MeI). The rate constants did not remain constant, but k3 decreased when k2 increased for both epimeric sugars. In water/NaOH/MeI, the methylation of the primary 6-OH was much more pronounced with an order of reactivity of O-6>O-2>O-3 for mannose and O-2>O-6>O-3 for glucose. The results are discussed with respect to the OH-acidity and the stereoelectronic, sterical, and solvent effects. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Carbohydrate Research 06/2014; 402. DOI:10.1016/j.carres.2014.06.005 · 1.92 Impact Factor
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    13th European Workshop on Lignocellulosics and Pulp, Sevilla, Spain; 06/2014
  • Yadong Zhao, Jiebing Li
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    ABSTRACT: Cellulose is the most abundant natural and renewable polymer and an important raw material for energy e.g. bioethanol, chemicals after e.g. various derivatisations, and materials e.g. of different films or composites. Trees and tunicates are common sources for cellulose and the practical application technique will be largely dependent on the cellulose structure obtained. In this work, woody cellulose (WC) obtained from typical softwood (spruce) and hardwood (eucalyptus) and tunicate cellulose (TC), obtained from 5 different tunicate species, Ciona intestinalis, Styela atlantica, Halocynthia roretzi, Styela plicata and Bothrylloides violaceous, have been comprehensively compared by Size Exclusion Chromatography for molecular weight distribution, XRay Diffraction for crystallinity, Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) for enzymatic digestability, Thermogravimetric Analysis and Differential Scanning Calorimetry for thermal properties, and Scanning Electronic Microscopy (SEM) for morphological structures. The comparison indicated that generally TC was of higher molecular weights than WC. The TC was composed of the almost-pure cellulose Iβ allomorph while the cellulose Iα was dominant in the WC. The higher degree of polymerization and crystallinity index were found in the TC which also made TC less accessible to enzymatic treatment than the WC. Reasonably, the TC with higher molecular weights showed better thermal stability than the WC though no very significant difference was found. Compared with relatively thin cellulose microfibril found in the WC, the longer and wider cellulose microfibril was characteristic for the TC which might make TC a more suitable candidate for composite reinforcement. From this study, it could therefore be concluded that different celluloses have different physical and chemical properties depending on the sources and the TC and WC would have great potentials to be used in producing biomaterials, chemicals and fuels. There are different advantages and disadvantages of these two celluloses, which will be decisive for different applications.
    247th ACS National Meeting & Exposition, Dallas, Texas, US; 03/2014
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    ABSTRACT: A key question for understanding marine ecosystems is the competitive interactions between predators and their prey particle community. A particularly important trophic interaction is between benthic tunicates and prey, driving the benthopelagic energy transfer in many marine systems. In general, classical methods for characterizing diets of marine animals feeding on planktonic species in situ are not well adapted to identify species specific interactions. However, molecular gut content analyses tools have proven promising since small quantities of prey DNA is detected using polymerase chain reaction (PCR). In this study, the intestine of tunicate Ciona intestinalis collected from deployed growth structures at 3 different ages and 3 depths were amplified using PCR with universal primers targeting the 18S rDNA gene in combination with a C3 tunicate blocking probe. Clones libraries were further constructed and prey particles analyzed by Sanger sequencing. In addition, the general contribution of eukaryotes and prokaryotes in the Ciona instestine were investigated using real time quantitative PCR (qPCR). Our data indicated that the class Conoidasida was the most abundant species with dominant taxa being Heliospora cf. Longissima, Heliospora caprellae, Thiriotia pugettiae and Cephaloidophora cf. Communis. This group of organisms has been found as parasites of intestinal tracts in marine organisms. Furthermore qPCR analysis indicated a significant proportion of prokaryotes in the intestine, but that the eukaryote contribution was higher. Our data also indicated that there was a positive correlation between size and contents of both prokaryotes and eukaryotes prey, while depth alone did not affect growth or food uptake. To our knowledge, this is the first report of Ciona trophic interaction using molecular gut content techniques. Our study indicates a significant link between both the eukaryotic and prokaryotic community, and that C. intestinalis could be an important vector for the Conoidasida parasite group's life history.
    247th ACS National Meeting & Exposition, Dallas, Texas, US; 03/2014
  • Yadong Zhao, Yujia Zhang, Jiebing Li
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    ABSTRACT: Glucomannans are bio-renewable polysaccharides and excellent raw materials e.g. for preparation of bio-based films with good barrier properties at a low cost. In addition, the glucomannan from spruce (SGM) could be obtained as a by-product from pulping industry for such applications under biorefinery concept. However, the films commonly possess poor properties especially for mechanical strengths. Reinforcement of the films with cellulose nanocrystals (CNs) has therefore been investigated in this study.
    NWBC 2014 - the 5th Nordic Wood Biorefinery Conference, Stockholm, Sweden; 03/2014
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    ABSTRACT: Xylan-lignin (XL), glucomannan-lignin (GML) and glucan-lignin (GL) complexes were isolated from spruce wood, hydrolyzed with xylanase or endoglucanase/β-glucosidase, and analyzed by analytical pyrolysis and 2D-NMR. The enzymatic hydrolysis removed most of the polysaccharide moieties in the complexes, and the lignin content and relative abundance of lignin-carbohydrate linkages increased. Analytical pyrolysis confirmed the action of the enzymatic hydrolysis, with strong decreases of levoglucosane and other carbohydrate-derived products. Unexpectedly it also revealed that the hydrolase treatment alters the pattern of lignin breakdown products, resulting in higher amounts of coniferyl alcohol. From the anomeric carbohydrate signals in the 2D-NMR spectra, phenyl glycoside linkages (undetectable in the original complexes) could be identified in the hydrolyzed GML complex. Lower amounts of glucuronosyl and benzyl ether linkages were also observed after the hydrolysis. From the 2D-NMR spectra of the hydrolyzed complexes, it was concluded that the lignin in GML is less condensed than in XL due to its higher content in β-O-4' ether substructures (62 % of side chains in GML vs 53 % in XL) accompanied by more coniferyl alcohol end units (16 vs 13 %). In contrast, the XL lignin has more pinoresinols (11 vs 6 %) and dibenzodioxocins (9 vs 2 %) than the GML (and both have ~13 % phenylcoumarans and 1 % spirodienones). Direct 2D-NMR analysis of the hydrolyzed GL complex was not possible due to its low solubility. However, after sample acetylation, an even less condensed lignin than in the GML complex was found (with up to 72 % β-O-4' substructures and only 1 % pinoresinols). The study provides evidence for the existence of structurally different lignins associated to hemicelluloses (xylan and glucomannan) and cellulose in spruce wood and, at the same time, offers information on some of the chemical linkages between the above polymers.
    Planta 02/2014; 239(5). DOI:10.1007/s00425-014-2037-y · 3.38 Impact Factor
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    ABSTRACT: The thermal degradation behavior and kinetics of spruce glucomannan(SGM) and its methylated derivatives were investigated using thermogravimetric analysis to characterize its temperature-dependent changes for use in specific applications. The results were compared with those obtained for commercial konjac glucomannan(KGM). The SGM and the KGM exhibited two overlapping peaks from 200 to 375 °C, which correspond to the intensive devolatilization of more than 59% of the total weight. Differences in the pyrolysis-product distributions and thermal stabilities appeared as a result of the different chemical compositions and molecular weights of the two GMs. The Friedman and Flynn-Wall-Ozawa isoconversional methods and the Coats-Redfern were adopted to determine the kinetic triplet of the intensive devolatilization region. Both GMs can be modeled using a complex mechanism that involves both a Dn-type and an Fn-type reaction. The comparative study of partially methylated GM indicated higher homogeneity and thermal resistance for the material with the higher degree of substitution
    Carbohydrate Polymers 02/2014; 106(1). DOI:10.1016/j.carbpol.2014.01.086 · 4.07 Impact Factor
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    ABSTRACT: The amination of industrial softwood kraft lignin was conducted using the Mannich reaction to modify the lignin structure for value-added applications. To understand the reaction mechanism and to quantify the amount of amine groups that were introduced, different types of NMR analyses were performed. The lignin was also pretreated by phenolation to increase its reactivity and the amount of the amine groups that were introduced. The Mannich reaction was very selective at the C-5 position of the guaiacyl units and complete under acidic conditions with ∼11-fold amounts of reagents of dimethylamine and formaldehyde over either model lignin (4-hydroxy-3-methoxyacetophenone, HMAP) or industrial spruce kraft lignin (LignoBoost lignin, LBL). For LBL, 28 amine groups were introduced over 100 aromatic rings. By weight, the nitrogen content was 2.5%. The aminated lignin was found to possess a higher molecular mass, reaching a Mp of 4.9 × 103 Da compared to the original 3.9 × 103 Da, and with a considerably increased dispersibility, especially in a dilute aqueous solution of hydrochloric acid (pH = 3), namely 5.2 mg/ml. With a preceding phenolation treatment, which increased the amount of phenolic aromatic rings available for the Mannich reaction, an introduction of 42 amine groups over 100 aromatic rings, or a nitrogen content of 4.8%, was obtained, which caused a further increase of the molecular mass to 5.1 × 103 Da (Mp) and of dispersibility in the aqueous solution of hydrochloric acid up to 32.0 mg/ml. The aminated lignins with or without the phenolation pretreatment formed very stable colloidal suspensions in water, with large particle sizes (391 and 39 nm), high zeta potentials (31.6 and 27.2 mV), and large charge densities (1.6 and 1.2 × 10−7 equiv./ml, respectively). The potential value-added applications of these modified lignins with high amine contents include use as surfactant chemicals, polycationic materials and slow-release fertilisers, among others.
    Industrial Crops and Products 01/2014; 52:729-735. DOI:10.1016/j.indcrop.2013.11.035 · 2.84 Impact Factor
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    ABSTRACT: The effects and mechanism of pulp delignification by laccases in the presence of redox mediators have been investigated on unbleached eucalyptus kraft pulp treated with laccases from Pycnoporus cinnabarinus (PcL) and Myceliophthora thermophila (MtL) and 1-hydroxybenzotriazole (HBT) and methyl syringate (MeS) as mediators, respectively. Determination of corrected kappa number in eucalyptus pulps after the enzymatic treatments revealed that PcL-HBT exhibited more remarkable delignification effect than MtL-MeS. To obtain further insight, lignin-carbohydrate complexes (LCCs) were fractionated and subsequently characterized by NMR, thioacidolysis (followed by GC and SEC) and pyrolysis-GC/MS analyses before and after the enzymatic treatments and their controls. It can be concluded that the laccase-mediator treatments altered the lignin structures in such a way that more lignin was recovered in the xylan-lignin fractions, as shown by Klason lignin estimation, with lower amounts of both syringyl (S) and guaiacyl (G) uncondensed units, as shown by thioacidolysis -GC, especially after the PcL-HBT treatment. The laccase-mediator treatment produced oxidation at Cα and cleavage of Cα and Cβ bonds in pulp lignin, as shown by pyrolysis-GC/MS. The general mechanism of residual lignin degradation in the pulp by laccase-mediator treatments is discussed in the light of the results obtained.
    Biomacromolecules 07/2013; 14:3073-3080. DOI:10.1021/bm4006936 · 5.75 Impact Factor
  • Yadong Zhao, Yujia Zhang, Jiebing Li
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    ABSTRACT: High performance films were prepared from tunicate cellulose isolated from Ciona intestinalis and commercial Konjac glucomannan(KGM) or Galactoglucomannans (SGM) extracted from Spruce. The cellulose was pretreated by controlled acid hydrolysis, TEMPO oxidation or enzymatic hydrolysis before film forming, or it was dissolved directly in ionic liquid. The structures of the composite films were investigated by Fourier transform infrared (FTIR) spectrum and X-ray diffraction (XRD), and scanning electron microscope (SEM), UV-vis spectrophotometer, contact angle analysis(CA) and the physical properties of the films such as mechanical properties and thermal stability were also examined. The results indicated that although cellulose and KGM were well miscible with each other in forming composite films in all weight ratios of KGM to cellulose the composite films with cellulose to KGM ratios of 90:10, 80:20, 50:50 and 50:50 for regenerated, acidic hydrolyzed, TEMPO-oxidized and enzymatic treated cellulose whiskers respectively showed the best film performance. For the SGM and cellulose composite films, their properties were similar to those with KGM and cellulose. It has been shown that chemical modification or direct dissolution with ionic liquid of cellulose is an effective method to increase its processibility and glucomannan is a potential candidate to improve the mechanical properties of cellulose-based films. As green materials, the composite films from cellulose and glucomannan have expectedly a high value for potential use as packaging materials and coatings in the food and pharmaceutical industries.
    The 17th International Symposium on Wood, Fibre and Pulping Chemistry, Vancouver (BC), Canada; 06/2013
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    ABSTRACT: In this article, the feasibilities of five different monomer aromatic substances as calibration standards by analytical pyrolysis with gas chromatographic separation and mass selective detection (Py-GC/MS) were applied for the quantification of lignin in paper and pulp. The stabilities of these substances in the pyrolysis process were evaluated and the curves of peak response area to mass also were obtained. The results showed that the substances with exact same substitutions on the benzene ring as lignin units had good stabilities in the pyrolysis process with good lineabilities of peak response area to the mass curves, which implicated these substances can be applied as calibration standards in the liginin quick quantitative analyse without tedious pretreatments and structure changes.
    Journal of Analytical and Applied Pyrolysis 05/2013; 101:232–237. DOI:10.1016/j.jaap.2012.12.015 · 3.07 Impact Factor
  • Yadong Zhao, Jiebing Li
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    ABSTRACT: Today, tunicates are well-known as rich sources of unique biologically active metabolites including lipids and lipophilic compounds. This work has therefore dealt with comprehensive analysis of the lipid and lipid class content of Ciona intestinalis by advanced techniques, such as NMR and MALDI-TOF MS, aiming at knowledge extension and application potential of the Ciona as a nutritional or functional ingredient for food and medicine. Neutral lipids, polar lipids and glycolipids were found to be predominant lipid classes. The distribution patterns of fatty acids were found largely different in these lipids while generally there were significant amounts of eicosapentaenoic acid, docosahexaenoic acid and polyunsaturated fatty acids present in the Ciona, indicating good utilization perspectives in food industry. Phospholipids consisted largely of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. As an ongoing work, as one form of the phospholipids present, plasmalogen will be fractionated and examined for its potential medical applications.
    245th ACS National Meeting & Exposition, New Orleans, US; 04/2013
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    ABSTRACT: Lignin, the second most abundant component after cellulose in biomass, has been examined in this study as a fuel for direct conversion into electricity using direct carbon fuel cells (DCFC). Two different types of industrial lignins were investigated: Lignosulfonate (LS) and Kraft lignin (KL), in their commercial forms, after their blending with commercial active carbon (AC) or after alteration of their structures by a pH adjustment to pH 10. It was found that the open circuit voltage (OCV) of the DCFC could reach around 0.7 V in most of the trials. Addition of active carbon increased the maximum current density from 43–57 to 83–101 mA cm−2. The pH adjustment not only increased the maximum current density but also reduced the differences between the two types of lignins, resulting in an OCV of 0.68–0.69 V and a maximum current density of 74–79 mA cm−2 from both lignins. Typical power density was 12 (for KL + AC) and 24 mW cm−2 (for LS + AC). It is concluded that a direct lignin fuel cell is feasible and the lignin hydrophilicity is critical for the cell performance.
    RSC Advances 03/2013; 3(15):5083-5089. DOI:10.1039/C3RA23418E · 3.84 Impact Factor
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    ABSTRACT: It is of both theoretical and practical importance to develop a universally applicable approach for the fractionation and sensitive lignin characterisation of Lignin-Carbohydrate Complexes (LCCs) from all types of lignocellulosic biomass, both natively and after different types of processing. In the present study, the previously reported fractionation approach that is applicable for eucalyptus (hardwood) and flax (non-wood) was further improved by introducing an additional step of barium hydroxide precipitation to isolate the mannan-enriched LCC (glucomannan-lignin, GML) to suit softwood species as well. Spruce wood was used as the softwood sample. As revealed by the recovery yield and composition analysis, all of the lignin was recovered in three different LCC fractions: a glucan-enriched fraction (glucan-lignin, GL), a mannan-enriched fraction (glucomannan-lignin, GML) and a xylan-enriched fraction (xylan-lignin, XL). All of the LCCs had high molecular weights and were insoluble or barely soluble in a dioxane-water solution. Carbohydrate and lignin signals were observed in (1) H, (13) C CP-MAS and normal- or high-sensitivity 2D HSQC NMR analyses. The carbohydrate and lignin constituents in each LCC fraction are therefore believed to be chemically bonded instead of physically mixed with one another. The three LCCs fractions were found to be distinctly different from each other in their lignin structures, as further revealed by highly sensitive analyses using thioacidolysis-GC, thioacidolysis-SEC and pyrolysis-GC analyses. © 2013 The Authors. The Plant Journal © 2013 Blackwell Publishing Ltd.
    The Plant Journal 01/2013; 74(2). DOI:10.1111/tpj.12124 · 6.82 Impact Factor
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    ABSTRACT: Unbleached Eucalyptus kraft pulps were treated by three methods and the bleaching effects have been evaluated. The treatments were performed by a laccase-mediator system (LMS), refining (R), and urea (U) alone and in combination of these methods. The bleached pulps were characterized in terms of κ number, hexenuronic acid content, brightness, and viscosity. In addition, the lignin-carbohydrate complexes (LCCs) were fractionated and characterized with regard to the fractionation yield, lignin content, and carbohydrate composition. Moreover, the 1H nuclear magnetic resonance spectra were recorded and the thioacidolysis-gas chromatography and thioacidolysis-size exclusion chromatography analyses were performed. The LMS treatment resulted mainly in a slightly better delignification as manifested by a κ number (K no.) reduction of 0.8 units. The effects of the U treatment included delignification (1.4 κ units), hexenuronic acid removal (3 μmol g-1), and improved pulp brightness (3.4 ISO units). The R treatment darkened the pulp (3 ISO units), whereas the bleaching of the R-pulp by subsequent LMS or U treatment enhanced the brightness (0.5 unit more) or delignification (0.3 unit more). The residual lignin in the pulp samples was present mainly as xylan-lignin. The Klason lignin content from the xylan-lignin fraction decreased as the degree of delignification increased. The pulp darkening followed by the R treatment was interpreted as the result of the formation of condensed lignin structures, but these condensed lignins were substantially removed by the subsequent LMS or U treatment.
    Holzforschung 01/2013; 67(6). DOI:10.1515/hf-2012-0140 · 2.34 Impact Factor
  • Yadong Zhao, Jiebing Li
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    ABSTRACT: Science and technology continue to move the development focus towards renewable, sustainable and environmentally friendly materials. Cellulose and its derivatives are of growing importance in the field due to cellulose’s abundant availability, renewability, biodegradability, high crystallinity, good processability and high specific strength and modulus. Commonly, natural cellulose is obtained from woody biomass while tunicates are the only animals known to also produce cellulose. Since tunicate cellulose (TC) is even more highly crystalline than the woody cellulose and has many other unique properties, such as being of high purity, high mechanical strength and ultra-fine nanofibrillar network structure, TC is nowadays becoming a promising biopolymer for several applications, including nanocomposite materials. However, detailed study on TC preparation and characterization from different tunicate species is rare and more systematic researches are needed to facilitate its applications in the future. In this work, therefore, TC preparation and characterization have been performed. A TC preparation procedure, composed of 1) prehydrolysis with acidic aqueous H2SO4 solution, 2) digestion with aqueous NaOH/Na2S solution and 3) defibration and bleaching with aqueous NaClO solution, has been followed and pure TCs from 5 different tunicate species, Ciona intestinalis, Styela atlantica, Halocynthia roretzi, Styela plicata and Bothrylloides violaceous, have been obtained. In the procedure, all other non-cellulose polysaccharides were removed during the prehydrolysis step as revealed by sugar composition analysis using ion chromatography (IC). All proteins have been removed during the digestion step as revealed by FTIR analysis and total nitrogen content analysis. Cellulose bundles or aggregates were defibrated and bleached in the last step by using NaClO. The TCs obtained are under systematic characterization, for example, by Size Exclusion Chromatography (SEC) for molecular weight distribution, by X-Ray Diffraction (XRD) for crystallinity, by Scanning Electronic Microscopy (SEM) for morphological structures and by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) for thermal properties. As a further study, nanocellulose will be produced by acid hydrolysis of the TCs obtained and characterized by Atomic Force Microscopy (AFM). Application investigation will focus on the production of biodegradable nanocomposites with enhanced mechanical properties or specific biological functions.
    The 5th Workshop on Cellulose, Regenerated Cellulose and Cellulose Derivatives, Örnsköldsvik, Sweden; 11/2012
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    ABSTRACT: Miscanthus × giganteus bark was subjected to mild fractionation with peroxyformic acid by a two stage process. A factorial experimental design was used to study and quantify the effect of the variables (formic acid concentration (80–90%), hydrogen peroxide concentration (0.2–0.4%), temperature of the first stage (60–80 ºC), and treatment time of the second stage (60–120 min)) on the main parameters of fractionation: pulp yield, remaining lignin and total polysaccharides in pulp. The dependence of lignin precipitation rate on hydrogen peroxide concentration in liquor was also studied. Hydrogen peroxide concentrations inferior to 0.5% seems to be suitable to recover high percentages of lignin. The isolated lignin was analysed by 2D-HSQC, 13 C-and 31 P NMR spectroscopy, FTIR spectroscopy, size-exclusion chromatography and chemical analysis. The most important chemical modifications taken place in the lignin during the fractionation were identified: b-O-4' cleavage and hydrolysis of LC-bond structures. The C9-formula was also determined: C9H6.81O2.90(OCH3)0.68(COOH)0.07(OHPh)0.38(OHAl)0.33.
    Industrial Crops and Products 01/2012; 35(1):261-268. DOI:10.1016/j.indcrop.2011.07.013 · 2.84 Impact Factor
  • 11th International Symposium on Wood and Pulping Chemistry (ISWPC), Nice, France; 06/2011

Publication Stats

910 Citations
108.85 Total Impact Points

Institutions

  • 2000–2015
    • KTH Royal Institute of Technology
      • • Department of Fibre and Polymer Technology
      • • Division of Polymer Technology
      • • Division of Wood Chemistry and Pulp Technology
      Tukholma, Stockholm, Sweden
  • 2009
    • University of A Coruña
      • Department of Physical Chemistry and Chemical Engineering I
      La Corogne, Galicia, Spain