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  • 1.
    Gillgren, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gorzsás, András
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A one-pot set-up for real-time reaction monitoring by FTIR spectroscopy2016In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 50, no 3, p. 567-580Article in journal (Refereed)
    Abstract [en]

    This paper presents a method for monitoring solution reactions in real time using Fourier transform infrared (FTIR) spectroscopy. Compared to batch measurements or flow-through systems, where the reaction and spectroscopic measurements are spatially and temporarily separated, this method enables continuous FTIR spectroscopic measurements of reactions without delay and directly in the reaction vessel. The strengths are demonstrated, and the limitations of the method are highlighted using the reaction of a lignin model compound and a sulphite salt. The method is capable of identifying both kinetic and thermodynamic properties (e.g. reaction speed, intermediate species), allowing rapid and cost-effective optimisation of reaction parameters. While specificity can be limited, the non-destructive nature of the method facilitates direct coupling to other techniques to help resolve potential ambiguities. The method is of general interest in wet chemistry applications and in several areas of the lignocellulosic biomass field in particular, as it can provide new insights into natural and industrial reactions and processes.

  • 2.
    Gillgren, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of laccase-catalyzed cross-linking of organosolv lignin and lignosulfonates2017In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 105, no 1, p. 438-446Article in journal (Refereed)
    Abstract [en]

    Lignin, an underutilized by-product from chemical pulping of wood, can be modified enzymatically through oxidation by laccase. However, little is known about the molecular details surrounding the cross linking which is a result of the oxidation. To reduce this lack of knowledge, we used oxygen consumption rate data, phenolic content data and molecular weight data together with data from NMR and FTIR spectroscopy to.characterize laccase-catalyzed cross-linking of the industrial lignin preparations organosolv lignin and lignosulfonate. The organosolv lignin preparation had a M-n of 780 g/mol, a M-w of 5200 g/mol, and a phenolic content of 1.8 mmol/g. The lignosulfonate preparation had a M-n of 6000 g/mol, a M-w of 19800 g/mol, and a phenolic content of 1.1 mmol/g. Laccase-catalyzed oxidation of organosolv lignin was characterized by a relatively slow increase in molecular weight, decreased intensities for aromatic signals and p-hydroxycinnamyl groups, and increased intensity for beta-O-4' signals, whereas oxidation of lignosulfonates resulted in a very rapid increase in molecular weight, and strongly decreased intensities for aromatic signals. The data suggest that lignosulfonates cross-linked by couplings to the aromatic ring (e.g. 5-5' and 4-O-5'), whereas beta-O-4' coupling characterized cross-linking of organosolv lignin, probably involving cinnamyl alcohol end-groups. (C) 2017 Published by Elsevier B.V.

  • 3. Johansson, Kristin
    et al.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jarnstrom, Lars
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films2014In: Journal of Biological Engineering, ISSN 1754-1611, E-ISSN 1754-1611, Vol. 8, no 1Article in journal (Refereed)
    Abstract [en]

    Background:

    Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems.

    Results:

    When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability.

    Conclusions:

    The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining processes.

  • 4.
    Pareek, Nidhi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Adsorption of proteins involved in hydrolysis of lignocellulose on lignins and hemicelluloses2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 148, p. 70-77Article in journal (Refereed)
    Abstract [en]

    Protein adsorption onto eight lignocellulosic substances (six lignin preparations and two hemicelluloses) was investigated at pH 4.8 and at two different temperatures (4°C and 45°C). The kinetics of the adsorption of cellulase, xylanase, and β-glucosidase were determined by enzyme activity measurements. The maximum adsorption capacities, the affinity constants and the binding strengths varied widely and were typically higher for the lignins than for the carbohydrates. As indicated by BET and gel permeation chromatography, different substances had widely different surface area, pore size, weight average molecular weight, and polydispersity index, but these properties were difficult to relate to protein binding. In most cases, an increase in temperature from 4°C to 45°C and a low content of carboxylic acid groups, as indicated by Fourier-Transform Infra-Red (FTIR) spectroscopy, resulted in increased protein adsorption capacity, which suggests that hydrophobic interactions play an important role.

  • 5.
    Sundman, Ola
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Broström, Markus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Homogenous benzylation of cellulose: impact of different methods on product properties2015In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 49, no 9-10, p. 745-755Article in journal (Refereed)
    Abstract [en]

    This paper offers an evaluation of different methods for synthesizing benzyl cellulose and of how they affect characteristics such as solubility, degree of substitution, thermal stability and molecular weight of the products. Benzyl celluloses with degrees of substitution between 0.1 and 2.5 were synthesised from microcrystalline cellulose in (1) aqueous NaOH/Urea and (2) dimethyl sulfoxide/tert-butyl ammonium fluoride (DMSO/TBAF) systems in order to evaluate the different properties of the benzyl celluloses of low degree of substitution. In contrast to previous findings in the literature, both systems yielded soluble benzyl celluloses at degrees of substitution <0.5. Also in contrast to the literature, the low degree of substitution benzyl celluloses from both systems showed similar thermal properties. The filtration of the benzyl celluloses in DMSO/TBAF solutions before precipitation gave significantly higher solubility of the products and increased their thermal stability. The molecular weights of the benzyl celluloses of low degree of substitution (0.4 < DS < 1.25) were similar between the systems and differed in the range of one order of magnitude from the molecular weights of the higher degree of substitution benzyl celluloses. 13C-NMR data indicated differences in the substitution pattern between the two systems.

  • 6.
    Wang, Zhao
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Winestrand, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gillgren, Thomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jönsson, Leif J.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chemical and structural factors influencing enzymatic saccharification of wood from aspen, birch and spruce2018In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 109, p. 125-134Article in journal (Refereed)
    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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