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  • 1. Berglund, Linn
    et al.
    Anugwom, Ikenna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Aitomäki, Yvonne
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Turku, Finland.
    Oksman, Kristiina
    Switchable ionic liquids enable efficient nanofibrillation of wood pulp2017Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, nr 8, s. 3265-3279Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Use of switchable ionic liquid (SIL) pulp offers an efficient and greener technology to produce nanofibers via ultrafine grinding. In this study, we demonstrate that SIL pulp opens up a mechanically efficient route to the nanofibrillation of wood pulp, thus providing both a low cost and chemically benign route to the production of cellulose nanofibers. The degree of fibrillation during the process was evaluated by viscosity and optical microscopy of SIL treated, bleached SIL treated and a reference pulp. Furthermore, films were prepared from the fibrillated material for characterization and tensile testing. It was observed that substantially improved mechanical properties were attained as a result of the grinding process, thus signifying nanofibrillation. Both SIL treated and bleached SIL treated pulps were fibrillated into nanofibers with fiber diameters below 15 nm thus forming networks of hydrophilic nature with an intact crystalline structure. Notably, it was found that the SIL pulp could be fibrillated more efficiently than traditional pulp since nanofibers could be produced with more than 30% less energy when compared to the reference pulp. Additionally, bleaching reduced the energy demand by further 16%. The study demonstrated that this switchable ionic liquid treatment has considerable potential in the commercial production of nanofibers due to the increased efficiency in fibrillation.

  • 2.
    Chen, Genqiang
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
    Wu, Guochao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Alriksson, Björn
    Wang, Wei
    Hong, Feng F.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bioconversion of waste fiber sludge to bacterial nanocellulose and use for reinforcement of CTMP paper sheets2017Inngår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 9, nr 9, artikkel-id 458Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for the production of BNC by the submerged cultivation of Komagataeibacter xylinus. Compared with a synthetic glucose-based medium, the productivity of purified BNC from the fiber sludge hydrolysate using shake-flasks was enhanced from 0.11 to 0.17 g/(L x d), although the average viscometric degree of polymerization (DPv) decreased from 6760 to 6050. The cultivation conditions used in stirred-tank reactors (STRs), including the stirring speed, the airflow, and the pH, were also investigated. Using STRs, the BNC productivity in fiber-sludge medium was increased to 0.32 g/(L x d) and the DPv was increased to 6650. BNC produced from the fiber sludge hydrolysate was used as an additive in papermaking based on the chemithermomechanical pulp (CTMP) of birch. The introduction of BNC resulted in a significant enhancement of the mechanical strength of the paper sheets. With 10% (w/w) BNC in the CTMP/BNC mixture, the tear resistance was enhanced by 140%. SEM images showed that the BNC cross-linked and covered the surface of the CTMP fibers, resulting in enhanced mechanical strength.

  • 3. Chen, Zhi-Qiang
    et al.
    Abramowicz, Konrad
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Raczkowski, Rafal
    Ganea, Stefana
    Wu, Harry X.
    Lundqvist, Sven-Olof
    Mörling, Tommy
    Sjöstedt de Luna, Sara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Gil, Maria Rosario Garcia
    Mellerowicz, Ewa J.
    Method for accurate fiber length determination from increment cores for large-scale population analyses in Norway spruce2016Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 9, s. 829-838Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fiber (tracheid) length is an important trait targeted for genetic and silvicultural improvement. Such studies require large-scale non-destructive sampling, and accurate length determination. The standard procedure for non-destructive sampling is to collect increment cores, singularize their cells by maceration, measure them with optical analyzer and apply various corrections to suppress influence of non-fiber particles and cut fibers, as fibers are cut by the corer. The recently developed expectation-maximization method (EM) not only addresses the problem of non-fibers and cut fibers, but also corrects for the sampling bias. Here, the performance of the EM method has been evaluated by comparing it with length-weighing and squared length-weighing, both implemented in fiber analyzers, and with microscopy data for intact fibers, corrected for sampling bias, as the reference. This was done for 12-mm increment cores from 16 Norway spruce (Picea abies (L.) Karst) trees on fibers from rings 8-11 (counted from pith), representing juvenile wood of interest in breeding programs. The EM-estimates provided mean-fiber-lengths with bias of only +2.7% and low scatter. Length-weighing and length2-weighing gave biases of -7.3% and +9.3%, respectively, and larger scatter. The suggested EM approach constitutes a more accurate non-destructive method for fiber length (FL) determination, expected to be applicable also to other conifers.

  • 4. Donev, Evgeniy
    et al.
    Gandla, Madhavi Latha
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mellerowicz, Ewa J.
    Engineering non-cellulosic polysaccharides of wood for the biorefinery2018Inngår i: Frontiers in Plant Science, ISSN 1664-462X, E-ISSN 1664-462X, Vol. 9, artikkel-id 1537Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Non-cellulosic polysaccharides constitute approximately one third of usable woody biomass for human exploitation. In contrast to cellulose, these substances are composed of several different types of unit monosaccharides and their backbones are substituted by various groups. Their structural diversity and recent examples of their modification in transgenic plants and mutants suggest they can be targeted for improving wood-processing properties, thereby facilitating conversion of wood in a biorefinery setting. Critical knowledge on their structure-function relationship is slowly emerging, although our understanding of molecular interactions responsible for observed phenomena is still incomplete. This review: (1) provides an overview of structural features of major non-cellulosic polysaccharides of wood, (2) describes the fate of non-cellulosic polysaccharides during biorefinery processing, (3) shows how the non-cellulosic polysaccharides impact lignocellulose processing focused on yields of either sugars or polymers, and (4) discusses outlooks for the improvement of tree species for biorefinery by modifying the structure of non-cellulosic polysaccharides.

  • 5. Duan, Ran
    et al.
    Westerlind, Bo S.
    Norgren, Magnus
    Anugwom, Ikenna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Virtanen, Pasi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Finland.
    Fibre Stress-Strain Response of High-Temperature Chemi-Thermomechanical Pulp Treated with Switchable Ionic Liquids2016Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, nr 4, s. 8570-8588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The removal of lignin from a high-temperature chemi-thermomechanical pulp (HT-CTMP) using a switchable ionic liquid prepared from an organic superbase (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)), monoethanol amine (MEA), and SO2 was investigated. The objective was to measure the fibre properties before and after removal of the lignin to analyse the contributions from lignin in the HT-CTMP fibre to the tensile properties. It was found that the fibre displacement at break - measured in zero span, which is related to fibre strain at break - was not influenced by the lignin removal in this ionic liquid system when tested dry. There was a small increase in displacement at break and a reduction in tensile strength at zero span when tested after rewetting. At short span, the displacement at break decreased slightly when lignin was removed, while tensile strength was almost unaffected when tested dry. Under rewetted conditions, the displacement at break increased and tensile strength decreased after lignin removal. Nevertheless, no dramatic differences in the pulp properties could be observed. Under the experimental conditions, treatment with the ionic liquid reduced the lignin content from 37.4 to 15.5 wt%.

  • 6. Hägglund, Håkan
    et al.
    Norberg, Ole
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Edström, Per
    Prediction of optical variations in paper from high resolution measurements of paper properties2013Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 28, nr 4, s. 596-601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method to predict optical variations from high resolution measurements of paper properties is evaluated in this work. The method combines the point-wise values of high resolution maps of filler content and grammage with an empirical model derived in an earlier study to predict the spatial optical variations in paper. The method has been applied on two paper samples, a laboratory paper and a commercial 80 g/m(2) copy paper. The optical variations have been predicted at a scale of 1 mm(2). Validation has been made by using a high resolution spectrophotometric setup to measure the spatial reflectance variations in the paper. The results show that for the samples used, the influence of filler content variations and density variations on the optical variations is small compared to influence of the grammage variations.

  • 7.
    Hållberg, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Produktion BM/FS. Produktionsavsnitt Färdigställning: Interna Reklamationer*Process*Kostnader2014Independent thesis Basic level (university diploma), 5 poäng / 7,5 hpOppgave
    Abstract [sv]

    Denna rapport beskriver projektarbetet om tydliggörandet av vilka och hur mycket resurser som krävs i samband med interna reklamationer på copyprodukter samt skapandet av en beräkningsmall som tydliggör kostnaderna vid dessa reklamationer.

    Målet är att beräkningsmallen ska tydliggöra vilka kostnader det blir för interna reklamationer och därmed öka förståelsen för hur viktigt det är att alltid tillverka produkter med rätt kvalitet i alla processavsnitt genom hela produktionen.

     

    För att belysa vilka och hur mycket resurser som krävs för att ta hand om interna reklamationer på copyprodukter har berörda befattningar intervjuats efter en enhetlig intervjumall. Intervjumallen belyser frågor som vad respektive befattning har för huvuduppgift i samband med interna reklamationer, hur många arbetstimmar som krävs för varje befattning och vilka kostnader som uppstår.

     

    Resultaten av sammanställningen för interna reklamationer för copyprodukter redogörs. Beräkning av kostnader för interna reklamationer för copyprodukter tydliggörs genom tre tabeller. Kostnader för intern/extern personal och produktions-bortfall per maskin beräknas i en framtagen beräkningsmall.

    Kostnader för förbrukningsmaterialen redogörs. Därefter visas alla kostnader i en pivottabell.

    Förslag ges på hur en förbättring av kvalitén på copyprodukter kan ske för att undvika problem som interna reklamationer.

  • 8. Johansson, Kristin
    et al.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Järnström, Lars
    Oxygen scavenging enzymes in coatings: effect of coating procedures on enzyme activity2011Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, nr 2, s. 197-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oxygen content in food packaging may be reduced by attaching oxygen scavengers to the packaging material. The critical parameters that determine the oxygen-scavenging ability of an enzyme-based coating i.e. pH, heat and coating color formulation were evaluated. Glucose oxidase, catalase and glucose were added to latex dispersions in the preparation of the coating colors. The enzymes were entrapped in the coating layers after coating and drying. The clay concentration and drying conditions were varied and the enzymatic activity of the coated layer was evaluated. The need for a pH-buffered system was also studied and the results indicated that, when using a carboxylated latex of a standard coating grade, a buffered system was not needed. A rapid drying at a high temperature was preferred over a slow drying at a low temperature in order to prevent pre-oxidation of the substrate in the wet coating color. The scavenging capacity of the coating was dependent on the amount of substrate for the enzyme reaction left after complete drying. The concentration of clay in the coating formulation was shown to have a marked impact on the oxygen-scavenging ability of the coated layer. The enzyme activity was increased by the addition of clay up to a pigment volume concentration (PVC) of ca. 10%. At higher concentrations of clay, the enzyme activity decreased until the critical pigment volume concentration (CPVC) was reached, probably due to the prevention of diffusion of oxygen and consumption of glucose in the coating process before the layer was completely dried. Further additions of clay above the CPVC resulted in an increased enzyme activity, probably due to the creation of a porous structure.

  • 9. Larsson, Per Tomas
    et al.
    Karlsson, Rose-Marie Pernilla
    Westlund, Per-Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wågberg, Lars
    Internal Structure of Isolated Cellulose I Fibril Aggregates in the Water Swollen State2017Inngår i: Nanocelluloses: their preparation, properties, and applications / [ed] Agarwal, UP Atalla, RH Isogai, A, American Chemical Society (ACS), 2017, s. 91-112Konferansepaper (Fagfellevurdert)
    Abstract [en]

    By combining H-2-NMRD and CP/MAS C-13-NMR measurements of water-based cellulose gels and of water swollen pulps it was possible to estimate the nature of the interior structure of cellulose fibril aggregates. A set of samples with high cellulose purity and low charge was used. The interpretation of data was based on a relaxation model describing the exchange dynamics for deuterium exchange between water molecules and cellulose hydroxyl groups. The theoretical model used made it possible to calculate cellulose surface-to-volume ratios (q-values) from both H-2-NMRD and CP/MAS C-13-NMR data. Good consistency between H-2-NMRD and CP/MAS C-13-NMR data was found. In all investigated samples the cellulose fibril aggregates showed a different degree of "openness" interpreted as the presence of interstitial water inside fibril aggregates. One result also showed that an increased degree of fibril aggregate openness results from the TEMPO-oxidation. Common to all samples was that in the water swollen state water molecules could access part of the fibril aggregate interior.

  • 10.
    Martín, Carlos
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wu, Guochao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wang, Zhao
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Stagge, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Formation of microbial inhibitors in steam-explosion pretreatment of softwood impregnated with sulfuric acid and sulfur dioxide2018Inngår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 262, s. 242-250Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Wood chips of Norway spruce were pretreated by steam explosion at 195–215 °C after impregnation with either sulfuric acid (SA) or sulfur dioxide (SD). The effects of different pretreatment conditions on formation of microbial inhibitors were investigated, and the inhibitory effects on yeast of pretreatment liquids and of specific inhibitors that were found in the pretreatment liquids were elucidated. Whereas the concentrations of most inhibitors increased with increasing pretreatment temperatures, there were exceptions, such as formaldehyde and p-hydroxybenzaldehyde. The highest concentration of each inhibitor was typically found in SD-pretreated material, but formic acid was an exception. The toxic effects on yeast were studied using concentrations corresponding to loadings of 12 and 20% total solids (TS). Among individual inhibitors that were quantitated in pretreatment liquids, the concentrations of formaldehyde were by far most toxic. There was no or minimal yeast growth in the formaldehyde concentration range (5.8–7.7 mM) corresponding to 12% TS.

  • 11.
    Pesquet, Edouard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC). Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Arrhenius Laboratories, Department of Ecology, Environment and Plant Sciences (DEEP), Stockholm University, Sweden.
    The COST action FP1105: a research network to understand wood cell wall structure, biopolymer interaction and composition2016Inngår i: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, nr 12, s. 1103-1104Artikkel i tidsskrift (Annet vitenskapelig)
  • 12.
    Strunk, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Öman, Tommy
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gorzsás, András
    Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Characterization of dissolving pulp by multivariate data analysis of FT-IR and NMR spectra2011Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, nr 4, s. 398-409Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several grades of dissolving pulps have been analyzed using FT-IR, solid state13C NMR and two dimensional1H-13C HSQC NMR spectroscopy to obtain an extensive data set for further characterization. The selection of the dissolving pulps with high cellulose purity was based on pulping process, wood type and, intrinsic pulp viscosity. Multivariate data analysis was used to investigate how information derived from the spectroscopic data correlate to each of the selection criterion: wood type, process type and viscosity. The spectroscopic methods were also compared with common dissolving pulp analyses to see to what extent spectroscopy can predict pulp analyses.

    Correlations were found between the spectroscopic data and the pulp characteristics process type and wood type, but not for intrinsic viscosity. A reason for a good correlation to wood type appears to be the hemicelluloses composition, expressed as the xylose:mannose ratio by 2D NMR spectroscopy. For process type, 2D NMR showed the most characteristic property to be the amount of reducing ends in the cellulosic samples, which in turn strongly correlates to lower molecular weight for the sulfite samples as determined by molecular weight distribution.

    Many common, yet expensive and time consuming, pulp analyses could also be predicted by the achieved models. It can be concluded that investigations of dissolving pulp characteristics, especially concerning different wood and process types, can take advantage of the methods and models presented in this study.

  • 13. Svenningsson, Leo
    et al.
    Sparrman, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bialik, Erik
    Bernin, Diana
    Nordstierna, Lars
    Molecular orientation distribution of regenerated cellulose fibers investigated with rotor synchronized solid state NMR spectroscopy2019Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, nr 8, s. 4681-4692Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A regenerated cellulose fiber is, in contrast to cotton, a man-made fiber. In the fiber production, the cellulose polymer is subject to various processing steps, affecting the underlying molecular orientation distribution, which is a determining factor for mechanical properties of the fiber. In this work, the molecular orientation distribution was determined in a C-13 natural abundance Lyocell regenerated cellulose fiber bundle using rotor synchronized magic angle spinning NMR spectroscopy (ROSMAS) to investigate the chemical shift anisotropy (CSA). The recorded signal intensities were compared with an analytical model of the experiment to find the order parameters reflecting the orientation of the fiber. The CSA tensor was calculated using density functional theory for the crystalline cellulose II structure, commonly found in regenerated cellulose, and is required as an input parameter. The expected order parameter values were only found when approximating the glycosidic bond and its CSA tensor as being parallel to the molecular frame with the order parameter P2=0.45 +/- 0.02 compared to P2=0.46 +/- 0.02 obtained with wide angle X-ray scattering on a fiber bundle. To make this method accessible to the community, we distribute the Matlab script for the simulation of spectra obtained by the ROSMAS experiment at github.com/LeoSvenningsson/ROSMAS.

  • 14.
    Timmerfors, Jessica Gard
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Evaluation of novel drum chipper technology: pilot-scale production of short wood chips2019Inngår i: TAPPI Journal, ISSN 0734-1415, Vol. 18, nr 10, s. 585-592Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Impregnation of wood chips with acidic pulping liquors is improved when using short chip lengths. If the average wood chip length is too short, conventional chipping technology will generate excess small material, such as pin chips and fines. The possibility of using newly developed drum chipping technology to produce short-length wood chips was evaluated with a pilot drum chipper operating at different drum velocities and in-feed angles. With a drum velocity of 30 m/s, the average wood chip lengths and the combined fractions of pin chips and fines were 24 mm and 3.3%, 22 mm and 4.2%, and 17 mm and 8.5%. The highest fractions of total accept chips (large and small accepts), 89% to 90% without screening, were observed for drum velocities of 30-34 m/s and average wood chips lengths of 21-22 mm. The results indicate the potential of drum chipping technology for producing short wood chips with relatively high fractions of accept chips and tolerable fractions of pin chips and fines.

  • 15.
    Wahl, Cecilia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Kvalitets- och styrkevariationer hos returfibermassa vid produktion av brun kraftliner hos SCA Munksund2014Independent thesis Basic level (university diploma), 5 poäng / 7,5 hpOppgave
    Abstract [sv]

    Detta arbete har utförts för att se hur returfibermassans egenskaper varierar under en vanlig kraftlinerkampanj. De metoder som använts är standardiserade och omfattar malgradsmätning, styrkearkning och pappersprovning. Även pH-, konduktivitets- och redoxpotentialmätningar har utförts, samt askhaltsmätning. Resultaten visar på att pH och redoxpotentialen sjunker och massan blir surare efter ca. ett dygn efter att kampanjen startat. Det medför även att retentionen i massan försämras i och med att konduktiviteten ökar vid lågt pH-värde och låg redoxpotential. I övrigt håller de flesta mätningarna konstanta värden.

  • 16.
    Wang, Zhao
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Comparison of catalytically non-productive adsorption of fungal proteins to lignins and pseudo-lignin using isobaric mass taggingManuskript (preprint) (Annet vitenskapelig)
  • 17.
    Wang, Zhao
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pawar, PM
    Derba-Maceluch, Marta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Hedenström, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chong, Sun-Li
    Tenkanen, M
    Mellerowicz, E
    Jönsson, Leif J
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Bioprocessing properties of hybrid aspen expressing a Carbohydrate Esterase Family 5 acetyl xylan esterase under control of a wood-specific promoterManuskript (preprint) (Annet vitenskapelig)
  • 18.
    Wang, Zhao
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Winestrand, Sandra
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gillgren, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Jönsson, Leif J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Chemical and structural factors influencing enzymatic saccharification of wood from aspen, birch and spruce2018Inngår i: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 109, s. 125-134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The susceptibility of untreated and sulfuric-acid-pretreated aspen, birch, and spruce to analytical enzymatic saccharification was studied in relation to their chemical composition and physical-structural features. The analytical data collected covered the mass fractions of lignin, carbohydrates, and extractives, the release of acetic acid, formic acid, and uronic acids by acid and alkaline hydrolysis, crystallinity and crystallite size, syringyl: guaiacyl (S:G) ratio of lignin, cellulose accessibility, FTIR spectra, images from SEM and fluorescence microscopy, and susceptibility to enzymatic saccharification using enzyme mixtures with and without supplementary xylanase.In the absence of pretreatment the mass fraction yield of Glc on the original dry wood in the analytical enzymatic saccharification increased in the order birch (16 g kg−1) < spruce (35 g kg−1) < aspen (150 g kg−1). After acid pretreatment, the order changed to spruce (170 g kg−1) < aspen (290 g kg−1), birch (290 g kg−1). The relatively high recalcitrance of untreated birch was not possible to relate to mass fraction of lignin, S:G ratio, cellulose crystallinity, or mass fraction of acetyl, but rather to structural features, such as a more compact surface structure with high density and low cellulose accessibility. The relatively high sugar yields from both untreated and pretreated aspen suggest that aspen wood is well suited as feedstock for production of liquid biofuels and green chemicals in forest-based biorefineries.

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